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pH TEST BOOKS andINDICATOR PAPERSforSCIENCE AND INDUSTRYDetails and prices from :BOOKSSCIENTIFIC & TECHNICALLARGE STOCK OF BOOKS on the Biological, Physical,Chemical and Medical Sciences supplied from stock, or obtained to order.FOREIGN DEPARTMENT. Books not in stock obtained toorder with the least possible delay.LENDING LIBRARYSCIENTIFIC AND TECHNICALAnnual Subscription from f 2 15s.Prospectus post free on application.Quarterly list of New Books and New Editions added to the Librarysent post free to any address regularly.THE LIBRARY CATALOGUE, revised to December, 1963. PartI, the index of Authors and Titles. Part 11, the index of Subjects.The complete catalogue (2 parts), to Library Subscribers, LI 10s.;to non-subscribers, L2 15s.net; postages 4s. 3d.H. K. LEWIS & CO. LTD. 136, Gower Street, WCI. EUSton 4282(iibooks from ButterworthsADVANCES IN FLUORINE CHEMISTRY 4 & 5edited by M. Stacey, F.R.S., J. C. Tatlow, Ph.D., D.Sc.,and A. G.Sharpe, MA., Ph.D. 75s. eachby R. Feld, B.Sc., Ph.D., and P. L. Cowe, B.Sc.221 pages illus. S2s. 6d.by T. A. Turney, M.Sc.216 pages 35s.PROGRESS IN MEDICINAL CHEMISTRY 4edited by G. P. Ellis, B.Sc., Ph.D., F.R.I.C., and G. B. West,B.Pharm., DSc., Ph.D. 230 pages illus. 67s. 6d.THE ORGANIC CHEMISTRY OF TITANIUMOXIDATION MECHANISMSSTRUCTURE AND FUNCTION OFCONNECTIVE AND SKELETAL TISSUEedited by S. Fitton Jackson, R. D. Harkness, S. M. Partridge andG. R. Tristram 559 pages illus. L7Sponsored byThe International Union of Pure and Applied ChemistryCOORDINATION CHEMISTRY70 pages.illus. 25s.MICROCHEMICAL TECHNIQUES108 pages illus. 40s.NOMENCLATURE OF ORGANIC CHEMISTRYSections A and 0 Second Edition 25s. Section C 47s. 6d.XXth CONGRESS OF PURE AND APPLlED CHEMISTRY404 pages. illus. 75s.Student BooksCHEMISTRY: A UNIFIED APPROACHby J. W. Buttle, B.Sc., A.R.I.C., D. J. Daniels, B.Sc., Ph.D., F.R.I.C., andP. J. Beckett, B.Sc., Ph.D., A.R.I.C. 546 pages illus. 40s.ELEMENTARY ELECTROCHEMISTRYby A. R. Denaro, M.Sc., Ph.D., F.R.I.C. 228 pages illus. 22s. 6d.INTRODUCTION TO COLLOlD AND SURFACECHEMISTRYby D. J. Shaw, B.Sc., Ph.D. 195 pages illus. 32s. 6d.MODERN TEXTBOOK OF ORGANIC CHEMISTRYby G. P. Ellis, B.Sc., Ph.D., F.R.I.C. 478 pages illus.57s. 6d.BUTTERWORTHS 88 Kingsway London WC2(iiiTHE CHEMICAL SUPPLY CO LTDI//I:/ jllmanufacturers ofEster Solvents Alkyl & Aryl Ester PlasticisersFormaldehyde & HexamineSpecial Plastic G r d sCadmium Colours Aromatic ChemicalsMolybdic Products Copper FungicidesBack Numbers (less certain volumes now out of print)are available-4 Full technical details and sampleswill be sent on requestTHE CHEMICAL SUPPLY CO LTD7 IDOL LANE, EASTCHEAP, LONDON EC3Tel: Mansion House 6854Grams: Kemsupply, London E.C.3111 Annual Reports on theProgress of ChemistryInquiries are invited by:TEECEEMICAL SOCIETYBurhgton House!. Landon, W.Inorganic ChemistryVolume I: Principles and Non-metalsVolume 11: MetalsC. S. G. PHILLIPS ANDR. J. P. WILLIAMSAn up-to-date and comprehensive account of inorganic chemistry atan advanced undergraduate level. The facts of the subject are relatedthroughout to atomic structures and modern views on chemicalbonding, while very strong emphasis is laid on the comparativechemistry of the elements. Numerous text figuresEach volume 65s netMelting and CrystalStructureA. R. UBBELOHDEBy surveying current information in this field, this book aims tofocus attention on liquids considered as ‘melts’. Quasicrystallinemodels, and anti-crystalline models related to them, may often bebetter suited to describe liquids not too near their critical point thanthe quasi-gaseous analogy. Many avenues for research on fluid con-densed states of matter involve this approach, and this book hasbeen written to stimulate and serve in their exploration. Numeroustext-figures 63s netOXFORD UNIVERSITY PRESS(vii

ISSN:0365-6217    

DOI:10.1039/AR96562FP001

出版商:RSC    

年代:1965

数据来源: RSC

摘要:

ANNUAL REPORTSON THEPROGRESS OF CHEMISTRYGENERAL AND PHYSICAL CHEMISTRY1. INTRODUCTIONBy P. G. Ashmore(Department of Chemistry, Manchester University Faculty of Technology)ON the scores of scientific importance and research activity there are manytopics in General and Physical Chemistry that qualify for inclusion in eachissue of Annual Reports. The senior Reporter’s main task is to assess theseclaims against the available pages and the often fortuitous availability atthe time of Reporters for the chosen topics. It is extremely fortunate thatthere always seem to be enough able and willing authors to undertake thecollection of material throughout the year and to exert the very necessarycritical judgment at Christmas. There are some topics, however, whichhave not been dealt with in Annual Reports for such a long time thatrestarting them is a most formidable and daunting task.I would like tobe able to say that Dr. Haydon’s able article on liquid-liquid interfacesis the first of a revival group; there is no lack of work and interest insurface chemistry and there is a real need for frequent reports of a generalrather than a specialist kind. Unfortunately, the task of assessing theadvances and putting present work into focus on all fronts of surfacechemistry is too great for any one contributor, and provisional arrangementsfor further articles on rather more limited fronts suffered a severe setbackby the tragic death of Dr. Kipling. Nevertheless, I hope that surfacechemists will find some way of filling, before it is too late, a notable gapin the coverage of the past decade of Annual Reports.Three of the articles in this year’s Report cover a wide range of activityin reaction kinetics.The resurgence of work on direct investigations ofindividual elementary reactions of free atoms and radicals has receivedspecialist reports in various series of Advances and Progresses, but the moregeneral account of Drs. Thrush and Campbell will not only allow a widercircle of chemists to view the progress, but also provide a very valuableand convenient summary of rate data for kineticists.Two closely relevant types of investigation of elementary reaction (ion-molecule reactions and reactions in crossed molecular beams) are discussedby Dr. Henchman; as he points out, these extremely valuable and growingtechniques have been rather neglected in this country.Professor Bradleycontributes an extremely clear account of the coming-of-age of shock-waveinvestigations of chemical reactions, now that improvements in technique8 GENERAL AND PIIYSICSL CHEMISTRYallow us to take proper advantage of the high temperatures and homo-geneous conditions of the shocked gas to obtain accurate kinetic data.Dr. Collinson’s article on radiation chemistry reports a growth rate thatwould be enviable in many quarters of our national economy, but gavehim a particularly large field to cover. He has made a judicious selectionof work on some organic systems and on some aqueous solutions.The final article by Drs.Inman and White provides a very valuable assess-ment of the rapidly expanding work, both theoretically and industrially,on molten salts, a field where the interests and aims of physical and inorganicchemistry imperceptlibly merge2. LIQUID-LIQUID INTERFACESBy D. A. Haydon(Department of Colloid Science, University of Cambridge,Free School Lane, Cambridge)Introduction.-Liquid-liquid interfaces are usually discussed and re-viewed in association with air-water interfaces. This Report is thereforea departure from tradition which, whatever the disadvantages, at leastgreatly facilitates the presentation of the material. The work specificallycovered is that published during 1963-1965 although earlier publicationshave been mentioned where they are thought to be helpful. The occurrenceof liquid-liquid interfaces in emulsions and thin films, in many biologicalsystems, and in mass-transfer cells and columns makes the whole field verywide.Descriptions of various aspects of liquid-liquid interfaces at theintroductory level have been given by Davies and Rideall and, in the fieldof emulsions, Becher has produced a second edition of his book.2 Reviewscovering a number of aspects of liquid-liquid interfaces have appeared ina two-volume collection of article^.^ Although it is now t,hree years oldthe bibliography of work on liquid-vapour and liquid-liquid interfacescompiled by Stephens4 must also be mentioned.In the main part of this Report we shall discuss only systems in whichnew information has been obtained regarding the structure and propertiesof liquid-liquid interfaces.Of general interest, however, is the excellentwork of Princen and Mason on the shapes of fluid drops at fluid-liquidinterfaces in two- and three-phase systems 5 and also the recent work onthe formation and properties of thin hydrocarbon films under aqueoussolutions.6 In the stability of these films, which are approximately 60 Ain thicl~ness,~ we have a direct demonstration of the normal orientationand steric hindrance to interpenetration of adsorbed monolayers a t hydro-carbon-water interfaces, and a means to test in detail the hypothesis ofcolloid stability in hydrocarbons proposed by Mackor and Van der Waals.8Measurement of Interfacial Tension.-In most would-be accurate workJ.T. Davies and E. K. Rideal, “ Interfacial Phenomena, ” Academic, Press,Sew York and L:vdon, 1963.P. Becher, Emulsions, ” Rheinhold, New York, 1965.“ Recent Progress in Surface Science, ” Academic Press, New York and London:Vols. 1 and 2, eds. J. F. Danielli, K. 0. A. Pankhurst, and A. C. Riddiford, 1964. * D. W. Stephens, “ Gas/Liquid and Liquid/Liquid Interfaces-A Bibliography, ”Joseph Crosfield and Sons, London, 1962.H. M. Princen and S. G. Mason, J . Colloid Sci., 1965, 20, 156, 246.I. Langmuir and D. F. Waugh, J . Gen. Physiol., 1938, 21, 745; P. Mueller, D. 0.Rudin, H. Ti Tien, and W. C. Wescott, Nature, 1963, 194, 979; Circulation, 1962,Pt. 11, 26, 1107; J . Phys. Chem., 1963, 67, 534; P. Mueller and D. 0. Rudin, J .Theoret.Biol., 1963, 4, 268; T. Hanai, D. A. Haydon, and J. Taylor, J . Gen. Physiol., 1965,48, 59; C. Huang and T. E. Thompson, J . MoE. Biol., 1965, 13, 183; T. Hanai, D. A.Haydon, and J. Taylor, J . Theoret. Biol., 1965, 9, 278.C. Huang, L. Wheeldon, and T. E. Thompson, J . MoE. Biol., 1964, 8, 148;T. Hanai, D. A. Haydon, and J. Taylor, KoEloid-Z., 1964, 195, [l], 41; T. Hanai, D. A.Haydon, and J. Taylor, PTOC. Roy. Soc., 1964, A , 281, 377.E. L. Mackor and J. H. Van der Waals, J . Colloid Sci., 1952, 7, 53510 GENERAL AND PHYSICAL CHEMISTRYon liquid-liquid interfaces in recent years the drop-volume method ofinterfacial-tension measurement has been used. This entails the use of theempirical corrections proposed by Harkins and Brown for liquid-vapoursystern~.~ The measurement of the surface tension of pure liquids by thismethod is known to be reasonably accurate through comparison with resultsfrom the capillary rise and other techniques. Such confirmatory evidenceis, for obvious reasons, much more difficult to obtain for liquid-liquidinterfaces.It is therefore satisfying to note that quite close agreementbetween the drop-volume lo and the Wilhelmy plate l1 techniques has beeiiobtained for the n-heptane-water interface. A definitive check on theaccuracy of the drop-volume method for liquid-liquid interfaces is never-theless badly needed as it is evidently one of the most accurate of the moreconvenient methods. Another convenient method, that involving the duNouy ring, has recently been re-examined for liquid-liquid interfaces.l2 Asfor the Wilhelmy plate, zero contact angle is required between the measur-ing surface and one of the liquid phases.Rings wetted by aqueous solutionsare unsatisfactory owing to the influence of surface-active solutes on thecontact angle. It has been reported that if, however, the rings are madeoil wettable by coating with Teflon or polyethylene, the interfacial tensionsare considerably more reliable.l2 The du Nouy method nevertheless stilldoes not appear to be capable of such high accuracy as the drop-volumemethod. The development of the Wilhelmy plate technique for liquid-liquid interfaces has continued. Problems of buoyancy and contact anglefor oils on aqueous solutions of surface-active substances have now beensolved to the extent that interfacial tensions reproducible to h0.1 dynecm.-l have been reported for these systems.11, l3Interfaces Between Pure Liquids.-The investigation of the thermody-namic properties of liquid-liquid interfaces is usually complicated by thesignificant mutual solubility of the two phases.Thus, the interpretationof the temperature coefficients of the interfacial tensions to give interfacialexcess heats and entropies is by no means straightforward.l* The aliphatichydrocarbons against water, however, constitute one of the simpler inter-faces from this point of view, as the mutual solubility can, for most purposes,be neglected. Two investigations of the interfaces between normal aliphatichydrocarbons and water have been reported during the last five years.l5, loThe former is concerned only with hexane a t different temperatures butthe latter gives interfacial tensions at a range of temperatures for six hydro-carbons from n-hexane to n-hexadecane.From these data interfacial excessheats and entropies have been calculated, One of the more curious featuresof the results lies in the comparison of the entropies for hexane obtainedby the two sets of authors. Franks and Ives15 found a sharp maximumin the interfacial excess entropy at 34” while Aveyard and Haydon lo show* W. D. Harkins and F. E. Brown, J . Amer. Ohm. SOC., 1919, 41, 499.lo R. Aveyard and D. A. Haydon, Trans. Faraday SOC., 1965, 81, 2255.11 J. H. Brooks and B. A. Pethica, Trans. Faraduy Soc., 1964, 80, 208.J.A. Krynitsky and W. D. Garrett, J. C O W Sci., 1963, 18, 893.J. H. Brooks and Bc: A. Pethice, Tram. Paraday Soc., 1965, 61, 671.14 E. A. Guggenheim,15F. Franks end D. J. G. Ives, J . Chem. SOC.. 1960, 741.Thermodynamics,” North Holland Publ. Co., Amsterdam,1969HAYDON LIQUID-LIQUID INTERFACES 11entropies which are independent of temperature and similar for all thehydrocarbons. The maximum in the entropy was attributed to a changein the structure of water a t 34". However, it was found by Aveyard andHaydon that if 30% (v/v) n-octane was mixed with the n-hexane a pointof inflexion in the tension-temperature curve, giving a maximum in theentropy, appeared at about 34". On this evidence it seems likely that themaxima in the interfacial excess entropies originate in the hydrocarbonrather than in the water phase.Whether or not impurities in the hexaneused by Franks and Ives are the explanation of the discrepancy, the pheno-menon is of considerable interest and worthy of further investigation. Theinfluence of chain branching in the hydrocarbon on the properties of theinterface have been investigated by using 2,2,4-t1imethylpentane.~~ Whilethe tensions are significantly lower than for n-octane, the temperaturecoefficient of the tension was constant between 20" and 30" and equal tothat for the normal chain hydrocarbons.The poor prospects for the calculation of liquid-liquid interfacial tensionsfrom fundamental data is underlined by recent work on liquid-vapoursystems.ls Some investigators have, however, been concerned with theprediction of interfacial tensions from the values for the correspondingliquid-vapour interfaces. Fowkes l7 has argued that if two liquids interactonly through London dispersion forces then the interfacial tension, y12,should be given byY l 2 = 7 1 3- Y2 - (YldYzd)+ (1)where yf and y$ are the contributions of the dispersion forces to thetensions of the pure liquids.For saturated aliphatic hydrocarbons thewhole of the liquid-vapour tension is assumed to originate in dispersionforces and yd is equated to y. For interfaces between saturated aliphatichydrocarbons and other liquids, equation (1) therefore becomesY l 2 = Y1 + Y2 - (YldY2)* (2)From the surface tensions of various hydrocarbons and their interfacialtensions against wafer, the contribution of dispersion forces to the surfacetension of water has been estimated.A value of 214& 0.7 dynes cm.-lwas found for yla while y z changed from 18.4 to 29.9 dynes cm.-l. Inprinciple, therefore, the interfacial tension of any other non-polar liquidagainst water may be found. The equation works moderately well ifunsaturated hydrocarbons, aromatics in particular, are excluded. Themercury-water tension is predicted to be 425 & 2 dynes cm.-l as comparedwith the experimental value of 426 & 7 dynes cm.-l.Monomoleculaz Films At Liquid-Liquid IntePfaces.-These fihs may besubdivided into three main types which, in order of increasing complexity,are those of non-electrolytes, electrolytes, and polymers.At oil-water, andparticularly hydrocarbon-water, interfaces the behaviour of these films isrelatively uncomplicated by the large effects, found at air-water interfaces,which originate in the interactions between the non-polar parts of the filmmo1ecules.l To a fist approximation, the interfacial pressure of a film ofl6 T. S . Ree, T. Ree, and H. Eyring, J. Ohem. P h y ~ . , 1964, 41, 624,17F. M. Fowkes, J . Phys. Chem., 1962, 66, 382; 1963, 67, 263812 GENERAL AND PHYSICAL CHEMISTRYsmall moleciiles between dilute solutions can be predicted by means of asurface equation of state from a knowledge of the interfacial density ofthe film molecules. The form of these equations has remained a topic forlively discussion during the last few years.181 19Non-eZectroZytes.Little work has recently been reported on spread oradsorbed films of these substances at oil-water interfaces. Some data onwhat is probably the simplest of these systems, the normal aliphatic alcoholsadsorbed at aliphatic hydrocarbon-water interfaces, was reported in 1960.2OIn this work the interfacial tensions of dilute solutions of some lower alcoholsin water (equilibrated against the hydrocarbon phase) were measured asa function of alcohol concentration. The Gibbs adsorption equation wasused to calculate interfacial excess concentrations. In these systems theinterfacial excess concentrations are almost equal to the actual interfacialconcentrations, and thus it was possible to plot interfacial pressure againstinterfacial area per alcohol molecule.The results were closely representedby a two-dimensional Van der Waals equation with a zero intermolecularattraction term,I7(A - A,) = kTwhere 17 is the interfacial film pressure, ,4 is the interfacial area per inoleculeand A , is the value of A a t 17 = 00. The value of -4, was found to be18.5 A2 per molecule, in good agreement with comparable results froininsoluble films of alcohols at air-water interfaces. In this work, however,the experimental data were not of the highest precision, activity coefficientswere assumed to be equal to unity and the aliphatic hydrocarbon was amixture of straight- and branched-chain saturated molecules. With theinclusion of the activity coefficients and improvement of the accuracy theresults would nevertheless probably not change by more than a few percent. Subsequent work on dilute solutions of n-hexadecanol in n-heptaneagainst water has, subject to the neglect of activity coefficients, givensimilar good agreement with equation (3) with A , = 18.5 A2 per mole-cule.2l At the benzene-water interface equation (3) is also obeyed toa first approximation by n-propanol, n-decanol, and n-hexadecanol( A , = 18.5 &- 1 A2 per molecule) and n-heptyl acetate (A, = 43 & 4 A2 permolecule) .21 In this work, again, the activity coefficients were not availableand were assumed to be unity. More recently, alcohols from n-pentanol ton-tetradecanol were examined at the n-octane-water interface at tempera-tures ranging from 20" to 50°.22 The results are for rather high concentra-tions where the activity coefficients are not only unknown but are likely tohe appreciably less than unity.Until these activity coefficients are availablea test of equation (3) will not be feasible.While equation (3) is evidently applicable only to a two-dimensional18 G. M. Bell, S. Levine, and B. A. Pethica, Truns. Farday Xoc., 1962, 58, 904.19 F. M. Fowkes, J . Phgp. Chern., 1962, 66, 385; E. H. Lucmsen-Reynders andM. Van den Tempel, Proc. 4th Internat. Congr. Surface Activity, 1964 (in press);E. H. Lucassen-Reynders, Nature, 1966 (in press).20 D. A. Haydon and F. H. Taylor, Phil. Truns., 1960, 252, A , 225.21 G. T. Rich, Thesis, Cambridge, 1964.22 J.J. Jasper and B. L. Houseman, J . Phys. Chern.. 19G3, 67, 1548; 1965, 69,310; J, J. Jasper and R. D. Van Dell, ibid., 1965, 69, 481HAYDON : LIQUID-LIQUID INTERFACES 13gas it does, in fact, hold remarkably accurately for many films of non-electrolytes a t oil-water interfaces. Little attention has, however, beengiven to the theoretical basis of equation (3) for liquid-liquid interfaces.In principle the partition function for the interface from which the equationis derived must take some account of the nature of the solvent molecules,as, for instance, in the theory of the vapour interfaces of two-componentliquid mixtures.= No treatment of this type has, however, yet appeared.Some recent, but unpublished results of Aveyard, have shown that theadsorption of n-butanol a t water-n-aliphatic hydrocarbon interfaces isaffected to a small but significant extent, and in a systematic manner, byvariation of the chain length of the hydrocarbon.Electrolytes.Monomolecular films of ions a t liquid-liquid interfaces andthe problem of the structure of the associated electrical double layers werereviewed in 1964,24 although the publications covered were those up to1961 only. At this stage it was known that monolayers of strongly surface-active strong electrolytes such as alkyl trimethylammonium bromides andsodium alkyl sulphates obeyed, to a first approximation, the surface equationof state obtained by combining equation (3) with a term for the electro-static free energy of the interfa~e.~5 In its original form this latter termwas derived directly from the Gouy-Chapman theory for the potential ata planar impenetrable charged interface where all the ions were pointcharges.At high interfacial charge densities, however, experiments indi-cated that the interfacial pressures were seriously underestimated by thisequation of state 20, l3 and a theoretical analysis suggested that the principalreason for this was the neglect, in the expression of electrostatic free energy,of the finite size of the monolayer ions.26 More recently, attention has beencentred on the importance of the discreteness-of-charge effect in mono-molecular films a t liquid-air and liquid-liquid interfaces and an at tempthas been made to estimate the influence of this phenomenon on the inter-facial film pressure.18 Unfortunately, there are other corrections to theelectrostatic treatment which are of doubtful magnitude 24 and which tendto frustrate experimental checks of any specific correction. In short, thereare too many unknown, and too few measurable parameters.The ultimateneed for accurate experimental relationships between interfacial film pressureand interfacial area per ion has nevertheless stimulated some very carefulwork on both soluble and '' insoluble " ionic films at hydrocarbon-waterinterfaces-11, l3 The latter systems were studied by means of a liquid-liquid Langmuir trough technique, where the insoluble film molecules wereconfined with barriers and the interfacial pressures were measured by aWilhelmy plate meth0d.l' One particularly interesting conclusion has beenreached as a consequence of the repetition of earlier work on (insoluble)films at aliphatic hydrocarbon-water interfaces of equimolar mixtures of23 I.Prigogine and J. Marechal, J . Colloid Sci., 1957, 7 , 122; J. W. Belton andM. G. Evans, Trans. Puraduy SOC., 1945, 41, 1.z p D. A. Haydon, in " Recent Progress in Surface Science ", Academic Press, NewYork and London, 1964, Vol. 1, eds. J. F. Danielli, K. G. A. Pankhurst, and A. C.Riddiford, p. 94.25 J. T. Davies, Proc. Roy. SOC., 1951, A , 208, 224.26 D. A. Haydon and F. H. Taylor, Phil. Tram., 1960, 253, A , 25514 GENERAL AND PHYSICAL CHEMISTRYsodium octadecyl sulphate and octadecyl trimethylammonium bromide.11, 27At relatively high interfacial areas per ion equation (3) is closely obeyed,but at 57 A2 per ion a sudden condensation of the iilm occurs which con-tinues until it becomes almost incompressible at approximately 32 8 2 perion.The authors attribute this condensation to electrostatic interactionbetween the positive and negative film ions.An approach to electrical double-layer structure a t hydrocarbon-waterinterfaces which is complementary to the measurement of interfacial j i hpressures? is that of interfacial (contact) potential measurement. A crucialquestion in the setting up of an electrostatic model for ionized monolayersis the probability of the occurrence of counter-ions in the plane of, and inthe region behind the centres of the film ions.Some evidence has beenobtained from measurements of the interfacial potential 20, 28-30 which con-firms past suggestions that there are usually significant numbers of counter-ions in these regions.20, 25, 31 Interfacial-potential data have also been usedto give indications of the water dipole orientation in the presence of ionizedmonolayers a t n-decane-water interface^.^^ -30 Systems involving sodiumdodecyl sulphate and sodium chloride and dodecyl trimethylammoniumbromide and sodium chloride have been examined 28, 29 and, more recently,data on monolayers of cetyl trimethylammonium ions in presence of F-,C1-, Br-, I-, NO3-, and SCN- have been reported.30 Attempts to breakdown the net dipole term in the interfacial potential so as to give waterorientation a t the hydrocarbon surface and round the ionic groups haveyielded an apparently reasonable qualitative picture.A paper by Koenighas drawn attention to the need for care in the interpretation of surface-potential measurements and some indication of the complications that mayoccur in the interpretation of surface potentials for strongly dipolar mole-cules has recently appeared.33 For liquid-liquid interfaces the measurementof contact potentials has so far been achieved by means of placing it gold-plated vibrating electrode in the hydrocarbon phase. This techniqueobviously breaks down if there are ions or molecules present which aresoluble in the oil phase and hence are liable to adsorb on to the goldelectrode. A development which may help to overcome this dif6culty hasbeen reported by Zisman and his collaborators34 and consists of coatingthe electrode with Teflon.These authors used this electrode for studiesof films of volatile organic molecules on platinum where the electrode wasin the vapour phase, but it is possible that, in an oil phase, the adsorptionof many types of molecule on to Teflon may also be of negligible importance.The interpretation of electrokinetic potentials at liquid-liquid interfaceswas examined by several workers about five years ago. The systems studied27 J. N. Phillips and E. K. Rideal, Proc. Rog. Soc., 1955, A , 232, 149.2eD. A. Haydon, KoZloid-Z., 1962, 185, [2], 148.29 D. A. Haydon, KoZloid-Z., 1962, 187, [2], 146.a0 S. Minc and Z.Koczoromki, Roczniki Chem., 1966, 89, 469.31 A. J. Payens, Thesis, State University of Utrecht, 1955.32 F. 0. Koenig, Corniti! Ilbtern. Thermodyn., Cindt. E&rmhim., Cmpt. rend.33B. A. Pethica, M. M. Standish, 3. Minghs, and D. H. Ilea, Nature, 1966, 205,34K. W. Bewig and W. A. Zisman, J . Phys. Chem., 1963, 67, 130.Rdunion 3e, 1951, 299.348HAYDON : LIQUID-LIQUID INTERFACES 15consisted of dispersions of aliphatic hydrocarbons in aqueous solutions ofsurface-active anions and cations.35 The major diEculty in this field,namely the quantitative explanation of the large discrepancies bet weent'he electrokinetic potentials and those calculated from simple models ofthe electrical double layer, given the interfacial charge density, have stillnot been overcome.For small hydrocarbon droplets, as in oil-in-water emulsions, the presenceof the diffuse double layer in the hydrocarbon phase is usually inconse-quential as it is not able to develop fully. For small water droplets inhydrocarbon, on the other hand, the diffuse layer is more likely to be fullydeveloped in both phases, as was envisaged by Verwey and Niessen.%GElectrokinetic potentials of water droplets in benzene in presence of sub-stituted salicylates, oleates, sulphonates, or picrates have been shown tobe positive.37 Recent work, however, has shown that, on introducinginorganic electrolytes into the aqueous phase, it is the cations rather thanthe anions that influence the electrokinetic potential.38 The authors of thiswork have shown that an explanation of this phenomenon follows froman analysis of the equations for the double diffuse layer.Studies of protein films a t hydrocarbon-wa terinterfaces have continued to appear over the last few years.Althoughthere have been investigations of the rheology of protein films39 and ofthe partial displacement of proteins from interfaces, the basic problem withthese systems has remained their irreproducibility, stemming, presumably,from the tendency of proteins to adsorb and even spread irreversibly. Thelatter problem has been emphasized in an investigation of pepsin filmsusing a barrier technique and Wilhelmy plate.40 It was found that thepressure-area curve a t intermediate pressures moved to smaller areas thehigher the pressure of the film, as initially spread.In other words, thepepsin appeared to spread less completely the higher the pressure againstwhich it had to spread.The pendant -drop method of interfacial tension measurement has beenused to study the time dependence of the adsorption of bovine serumalbumin a t the n-octadecane-water interface.41 It was found, in agreementwith earlier work, that the interfacial area per molecule of the adsorbedprotein was considerably less than that found for protein spread at lowpressures. A discussion of the reasons for this situation has been givenby Ghosh and Bull in connexion with their investigation of chymotrypsinadsorption a t n-octadecane-water interfa~es.~2 A two stage process is en-visaged in which diffusion to the interface and spreading across the interfacePolymeric molecules.35 P.J. Anderson, Trans. Paraday Soc., 1959, 55, 1421 ; D. A. Haydon, Proc. Roy.36 E. J. W. Verwey and K. F. Niessen, Phil. Mag., 1939, 28, [7], 435.J. L. Van der Minne and P. H. J. Hermanie, J . Colloid Sci., 1952, 7 , 600; W.3a W. Rigole and P. Van der Wee, J . Colloid SCi., 1965, 20, 145.3D B. Biswas and D. A. Haydon, Proc. Roy. Soc., 1963, A , 271,296,317; Kolloid-Z.,40 L. Blight, C. W. N. Cumper, and V. Kyte, J, Colloid Sci., 1965, 20, 393.'IS. Ghosh and H. B. Bull, Biochim. Biophy8. Acta, 1963, 66, 150.42 S. Ghosh and H. B. Bull, Arch. Biochem. Biophys., 1962, 99, 121.Soc., 1960, A , W, 319.Albers and J. Th. G. Overbeek, ibid., 1959, 14, 501.1962, 186 [l], 6716 GENERAL AND PHYSICAL CHEMISTRYare t,he important factors.At low substrate concentrations the arrival ofprotein at the interface is suggested to be slow compared with the spread-ing, and in consequence, most of the interface should be covered withcompletely expanded molecules. At higher concentration the expansion ofthe protein molecules is more likely to be blocked by the presence of rapidlyaccumulating neighbours. The final result is thus likely to be a film ofonly partially expanded and some almost native protein which should showan area per molecule considerably less than tthe completely expandedmolecules3. REACTIONS IN DISCHARGE-FLOW SYSTEMlBy I. 116. Campbell and B. A. Thrush(Department of Physical Chemistry, Cambrdge)IN recent years the emphasis in chemical kinetics has been increasingl_vtowards the measurement of individual processes and an understanding ofthe rBle of the energy distribution in the reactants and products.So muchhas been published since Sugden’s Annual Report in 1959 on the kineticsof reactions of atoms and small radicals that this Report will be confinedto discharge-flow methods of studying such reactions. No attempt will bemade to include Molecular Beam or Shock Tube studies or any of the detailsof the work on chemiluminescence which can provide much information onenergy distributions.The use of electric discharges as a source of free atoms was pioneeredby Wood and by Bonhoeffer 2 some forty years ago, and a large numberof atomic reactions were studied semi-quantitatively by them and byH a r t e ~ k .~ These workers were limited, as the only quantitative detect,orsfor free atoms then available were the calorimeter and the Wrede-Hartecligauge, which are non-specific. The considerable increase in the use of dis-charge flow systems during the last ten years is almost entirely due to thedevelopment of specific methods for the measurement of the concentrationsof atoms and free radicals. These include chemiluminescence, gas-phasetitration, electronic absorption spectroscopy, mass spectrometry, and electronspin resonance.Chemiluminescence methods are highly specific and involve the measure-ment of the intensity of the yellow nitrogen afterglow, the air afterglowfrom 0 + NO, HNO emission from Htf NO in the red and near-infrared regions,or emission in these regions from recombining chlorine or bromine atoms.The intensities of these emissions are proportional to “I2, [O][NO], [H][NO]and [C1I2 and [BrI2 respectively, but the constant of proportionality maybe a function of total pressure or composition of the carrier gas.Suchsystems are normally calibrated by calorimetry or gas-phase titration ofthe active species. The behaviour of metastable electronically and vibra-tionally excited species can also be followed by their emission or absorptionspectra.Gaseous titration methods for free atoms are less specific and needindependent confirmation ; they are therefore discussed in the individualsections. Free atoms and radicals can readily be detected m a s spectro-metrically since their ionisation potentials are lower than the correspondingappearance potentials from the parent molecules.Calibration requires con-siderable care. Metastable species can also be detected from breaks in theionisation curves but their identification is not always certain.Unfortunately the absorption spectra of ground-state H, N, and 01 R. W. Wood, Proc. Roy. SOC., 1922, A , 102, 1.2 K. F. Bonhoeffer, 2. ph?/s. Chenz., 1924, 113, 199, 492; ibid., 1925, 116, 391.3 P. Herteck and I-. Kopsch, Natzcrwiss., 1929, 72718 GENERAL AND PHYSICAL CHEMISTRYatoms all lie in the vacuum-ultraviolet region, but, despite the difficultiesinvolved, this method has been used to study their reactions.4 The absorp-tion spectra of free radicals lie mainly in the more aceessible ultravioletregon, but so far only the hydroxyl radical5 has been studied in thisway.Although electron spin resonance provides a sensitive specific methodof detecting free atoms, the problems of calibration are considerable.Thespectrum is normally displayed in the differential form, whereas the area,under each peak is required and double integration is frequently needed.Errors due to high modulation amplitudes, power saturation, and thevariation of line width with relaxation time can readily occur. The sensi-tivity for the detection of free radicals is lower by a factor of the rotationalpa.rtition function due to the splitting of the spectrum into many lines.Such spectra generally involve electric dipole transitions, whereas the atomicresonances are magnetic dipole transitions.Useful discussions of calibra-tion methods have been given by Krongelb and Strandberg6 and West-enberg and de Haas.'Rate constants refer to room temperature (2Oo--25"c) unless otherwisestated in the following sections of the Report.=bogen Atoms.-Much of the recently published work on hydrogenactom reactions in the gas phase has used other sources of hydrogen atoms,such as radiolysis, mercury photosensitisation, or the hydrogen-oxygenreaction. A review of this topic has recently appeared.sThe study of hydrogen atoms in discharge flow systems appears simplesince there are no low-lying metastable or atomic states to complicate theinterpretation.There are, however, experimental difficulties, since the re-combination of hydrogen atoms on glass surfaces is frequently irreproducibleand affected by such species as water. Several workers have studied theheterogeneous recombination of hydrogen atoms by Smith's method inwhich the concentration gradient set up by hydrogen atom diffusion andsurface recombination in a side arm is measured. This yields a value of y,the fraction of collisions which lead to recombination on the walls or onan auxiliary probe. The theory of this technique has been improved byGreaves and Linnetti10 and extended by Wise and Ablow.ll There hashowever been controversy 1% l3 about the method of calculating the effectof the probe used by the latter authors.Glass and quartz surfaces give values of y of the order of 10-4 at roomtemperature 1 3 7 14 which is reduced to about 10-5 by coating with Teflon4F.A. Morse and F. Kaufman, J . Chem. Phy.9., 1965, 42, 1785.5 F. Kaufmm and F. P. Del Greco, Discuss. Farday SOC., 1962, 38, 128; idem.,* S . Krongelb and M. W. P. Strandberg, J . Chem. Phys., 1969, 81, 1196.7 A. A. Westenbe'? and N. de Haw, J . Chm. Phy8., 1964, 40, 3087.8B. A. Thrush, Progress in Reaction Kinetics," Pergamon, London, 1965,* W. V. Smith, J . Chm. Phys., 1943, 11, 110.9th Symposium on Cornbwtion, Academic Press, New York, 1963, p. 659.Vol. 3, a. 2.10 J. C. Greaves and J. W. Linnett, Trans. Furadq Soc., 1959, 55, 1338.11H. Wise and C. M. Ablow, J . Chem. Phys., 1958, 29, 634.1aK. Tsu and M.Boudart, Canad. J . Chem., 1961, 39, 1239.laB. J. Wood and H. Wise, J . Phys. Chem., 1961, 65, 1976.14B. J. Wood and H. Wise, J . Phy8. Chem., 1962, 66, 1049CAMPBELL AND THRUSH: DISCHARGE-FLOW SYSTEMS 19or a silicone.f5,16 Wood and Wise14 find that y for glass rises as thetemperature is lowered or raised, becoming a rapid second order processbelow -150"c or above 250"~. This is explained as a change from theRideal to the Hinshelwood mechanism of surface recombination. Valuesof y between 10-2 and 1 are found on Au, Al, Cu, Ni, Pd, Pt, Ti, and Wsurfaces,13 frequently with small positive temperature coefficients. Graphiteshows similar behaviour, but there is a parallel process with a larger activa-tion energy which yields small amounts of acetylene, ethane, and methane."Recent determinations of the rate of the homogeneous recombinationof hydrogen atoms gave rate constants (expressed as d[H,]/dt) of l0l6 (ref.18),8.9 x 1015 (ref. 19) and 3.4 x 1015 (ref. 20) in cm.6 mole-2 sec.-l for M = H2and 2.3 x 1015 for M = Ar (ref. 20). The values for hydrogen are generallylower than those obtained in older work.21-23 For argon the rate constantwas found to vary as T-* between 2 1 3 " ~ and 349'9, which if extrapolatedwould agree well with some shock-tube data on the reverse process 24although other data 2 5 s z6 from this source is consistent with an overall T-ldependence. A similar situation exists for M = H,. The importance of Has a third body in this reaction is still uncertain.An upper limit of 4.8 x 1014 cm.6 mole-, sec.-l has been reported forthe rate constant of the reaction(1)The two combination reactions of hydrogen atoms with diatomic mole-H + NO + M + HNO +- M + 48.6 kcal./mole (2)H + 0, + M + HO, + M + 46 kcal./mole (3)being almost equally exothermic and giving products with similar con-figurations with similar rate constants.Values of k, = 1.48 x 1016,8.7 x and 6.5 x 1015 cm.6 mole-2 sec.-l for M = H,, Ar, and He a t20"c have been determined28 by the HNO emission rnethod,a9 the rateconstant having a small negative temperature-dependence. A similarvalue of k, = 1.1 x l0l6 cm.6 mole-, sec.-l for M = H, was obtainedwith a calorimetric probe.30 The mechanism of the parallel formationH + N + M -+NH + Ma t room temperature .2cules studied are extremely similarl6 H.C. Berg and D. Kleppner, Rev. Sci. Imtr., 1962, 33, 248.l6 J. P. Wittke and R. IiE. Dieke, Phys. Rev., 1956, 103, 620.l7 A. B. King and H. Wise, J . Phys. C h . , 1963, 87, 1163.1* L. I. Avramenko and R. V. Kolesnikova, Izvest. Akact. Nauk S.S.S.R., Otdel.lo C. B. Kretschmer and H. L. Petersen, J . Chern. Phys., 1963, 39, 1772.ao F. S. Larkin and B. A. Thrush, Discws. Faraday SOC., 1964, 37, 112; idmyW. Steiner, Tram. Faraday SOC., 1936, 31, 623, 962.anH. M. Smdlwood, J . Amer. Chem. Soc., 1934, 56, 1642.asI. Amdur, J . Amr. C h . SOC., 1938, 80, 2347.24 J. P. Rink, J . Chm. Phys., 1962, 36, 262, 1398.a6 R. W. Patch, J . Chem. Phys., 1962, 38, 1919.E. A. Sutton, J. Chem. Phys., 1962, 38, 2923.C. Mavroyannis and C.A. Winkler, C a d . J . C h . , 1962, 40, 240.2% M. A. A. Clyne and B. A. Thrush, Discurs. Paraday SOC., 1962, B, 139.M. A. A.. Clyne and B. A. Thrush, Trans. Faraday SOC., 1961, 57, 1306.ao R. Simonaitis, J . Ph.ys. Chem., 1963, 87, 2227.khim. Nauk, 1961, 1971.10th Symposium on Combustion, Combustion Institute, 196420 GENERAL AXD PHPSICAL CHEMISTRYof electronically excited HNO in reaction (2) has also been discussed.Z8The subsequent reactionH + HNO -3 H, + NO (4)is very rapid, with a rate constant greater than 3 x 1O1O cm.3 mole-1 sec.-la t room ternperat~re.2~The reactions subsequent to (3) in discharge flow systems are rathermore complex.(5a)-+OH+OH (5b)+H,O + 0 (5c)(6)0 + O H + H + O , (7)also occur.Reaction ( 5 ) is very rapid; Clyne and Thrush31 have also shownthat 33 & 12% of it occurs by path (5a). They obtained a value ofk, = 8 x 1015 cm.6 mole-2 sec.-l for M = Ar a t 20"c using the HNOemission technique. A later calorimetric study under similar conditionsgave k, = 1.3 x 10l6 cm.6 mole-2 sec.-l in good agreenient.20 The muchlower value reported by Avrainenko and Kolesnikova 18 is based on theassumption that H02 is removed only by the reaction( 8 )which is unlikely in the presence of an excess of hydrogen atoms. Reaction(3) was found to have a negative temperature coefficient corresponding to aT-2 dependence or an activation energy of -2000 cal./mole. This extra-polates to give good agreement with measurements of the second explosionlimit of the hydrogen-oxygen reacti0n.~2~ 33 There is evidence that reac-tion (5b) yields vibrationally excited OH.34H + HOz+H, + 0,and in the absence of molecular hydrogenOH + OH+H,O + 0+ HO2 + H 2 0 2 + 0,The branching step in the hydrogen-oxygen reactionH + O , + O H + O (9)cannot be studied directly in discharge flow systems as the equilibrium istoo far to the left.Measurements of the reverse process, which are discussedlater, agree well with data from flames and explosion limits on the forwardreaction.31Schulz and Le have studied the isotope exchange reactionH + D2 +HD + D (10)between 100" and 2OO0c, finding a rate expression of 4.4 x 1012 exp(-7300/RT) ~ m . ~ mole-l sec.-l. The rate constants for this and otherisotopic combinations can be deduced from a recent study of the thermalexchange reaction between H2 and D2 36 in which it is suggested that higherrate constants in earlier work are due to oxygen diffusing through the31 M.A. A. Clyne and B. A. Thrush, Proc. F y . SOC., 1963, A , $3'75, 559.32 V. V. Voevodskii and V. N. Kondratiev, Progress in Reaction Kinetics ,"s3 R. R. Baldwin, 9th Symposium on Combustion, Academic Press, New Pork, 1963,34 P. E. Charters and J. C. Polanyi, Canad. J . Chem., 1960, 38, 1742.35 W. R. Schulz and D. J. Le Roy, Canad. J . Chem., 1964, 42, 4280.36 G. Boata, G. Careri, A. Cimino, E. Molinari, and G. G. Volpi, J . Chem. Php.,Pergamon, London, 1961, Vol. I, Ch. 2.p. 667.1956, 24, 783CAMPBELL AND THRUSH: DISCHARGE-FLOW SYSTEMS 21vessel walls. Shavitt 3' has examined this data and those from the ortho-para exchange in terms of transition-state theory.He shows that the morerecent data 36 give a better fit. His expressions deviate significantly fromthe Arrhenius form; readers are therefore referred to calculation I1 in hisfabulated rate constants.37Discharge-flow systems have been used more to study the energy dis-tribution in the products of hydrogen atom abstraction reactions than todetermine their rate constants. Garvin 38 and colleagues have shown thatthe reactionH + O,-+HO + 0,yields vibrationally excited OH in levels up to u = 9, which correspondsto the total exothermicity of the reaction, the effective "vibrational tem-perature " of the initial distribution being 9 0 0 0 " ~ . ~ ~H + N O , + O H + N O (12)appears to yield little vibrationally excited OH5 and its infrared emissionmust be partly due to H20 formed subsequently from OH.39 Mass spectro-metric studies 40 show that these reactions (11) and (12) have rate constantsof 1.6 x 1013 and 3 x 1013 (3111.3 mole-1 sec.-l respectively at 20"c.Polanyi and co-workers 34, 419 42 have also studied the infrared emissionby vibrationally excited species in the reaction of hydrogen atoms with Cl,,Br2, NOCI, etc.H + C1, -3 HCl + C1 (13)some 10% of the energy liberated appears as vibration of the HC1 formedwhich has up to five quanta of vibrational energy.41, *2 There is alsoevidence for excess rotational excitation, although the rapid rotationalrelaxation makes it difficult to determine the initial distribution.Thereaction D + C1, gives DC1 with a similar energy distribution to the HC1from H + Cl,.42 The other reactions have been examined in less detailbut their general features are similar. Bunker 44 and Polanyi 45 have madecalculations of the expected energy distributions in the products of thesereactions using Monte Carlo methods.1.1 kcal./mole and afrequency factor of about 10l1 ~ 1 1 1 . ~ mole-l sec.-l for the reactionH 3- CH, -3 H, -l- CH, (14)This frequency factor is much lower than that found by Kazmi, Diefendorf,and Le Roy4' for the reactionH + C&f,+H, + C,H, (15)The reactionIn the reactionJamieson 46 reports an activation energy of 7.437 I.Shavitt, J . Clzem. Phys., 1959, 31, 1359.38 J. D. McKinley, D. Garvin, and M. Boudart, J . Chem. Phys., 1955, 23, 784.3s D. Garvin, H. P. Broida and H. J. Kostkowski, J . ChenL. Phys., 1960, 32, 880.40 L. F. Phillips and H. I. Schiff, J . Chem. Phys., 1962, 37, 1233.41 J. K. Cashion and J. C. Polanyi, Proc. Roy. SOC., 1960, A , 258, 529.4 2 P. E. Charters and J. C. Polanyi, Discuss. Paraday SOC., 1962, 33, 107.43 E. W. R. Steacie, " Atomic and Free Radical Reactions," Reinhold, New York,44 N. C. Rlsis and D. L. Bunker, J . Chem. Phys., 1962, 37, 2713.4 5 J. C. Polanyi and S. D. Rosner, J . Chem. Phys., 1963, 38, 1028.4 6 J. W. S. Jamieson, Canad. J . Chem., 1964, 42, 1638.4 7 H. A. Kazmi, R. J. Diefendorf and D. J. Le Roy, Canad. J .Chern., 1963,41, 690.2nd ed., 195422 GBNERAL AND PHYSICAL OHlCIKISTRYtheir rate expression being 1.3 x lo1* exp (--8200/RT) ~ m . ~ mole-l sec.-l.Data from several sources support high frequency factors43 of about 1014 cm.3mole-1 sec.-l for hydrogen atom attack on paraffin hydrocarbons.8, 48The observed rate constant for hydrogen atom. removal in their reactionwith hydrogen peroxide is 6 x 1O1O ~111.~ mole-l sec.-l at room tempera-ture.49 This is an upper limit, since the mechanism and stoicheiometry arenot known. A value of 3.5 x loll exp (-2OOO/RT) ~111.~ mole-l sec.-lhas been found50 for the rate constant of the reactionH + NJ34 + NgH, + H, (16)Nitrogen Atom.-Although it has been accepted for some years that theyellow nitrogen afterglow arises from the recombination of ground state (48)nitrogen atoms, there has been considerable disagreement over methods formeasuring their concentration. The two methods are the titration ofnitrogen atoms with nitric oxideN + NO +N2 + 0 (17)i n which the end point is indicated by a change from the yellow nitrogen(N + N) and blue nitric oxide (N + 0) afterglows to the greenish airafterglow (0 + NO), and secondly the limiting HCN yield from reactionwith excess of ethylene or other olefin a t elevated temperatures.It wasgenerally agreed that the endpoint of the nitric oxide titration correspondedto oonsumption of ground-state nitrogen atoms, a point which has now beenestablished by e.s.r. ~tudies.5~~ Proponents of the HCN yield method52maintained that nitric oxide titration gave higher yields because an addi-tional energetic species in active nitrogen decomposed nitric oxide.Thisview is not consistent with the experiments cited 4, 7,51 or with the observa-tions using l5NO. In these, Kaufman and Kelso 53 have shown that theNO #I band emission in the products comes only from 14N + 0, and massspectrometric studies by Herron 54 and by Back and Mui S5 have shownthak the reaction with 15NO yields only 14N15N and no lW2, therebydemonstrating that 15N atoms are not liberated by decomposition of nitricoxide.Herron56 has recently shown that the reaction between nitrogen atomsand ethylene is not stoichiometric and occurs by a catalytic chain in-volving hydrogen atoms.The nitric oxide titration method can therefore be regarded as estab-lished; it involves a very rapid reaction; Clyne and Thrush57 obtained46 R.R. Baldwin, D. Jackson, R. W. Walker, and S. J. Webster, 10th Symposiumon Combustion, Combustion Institute, 1964.4 s S. N. Foner and R. F. Hudson, J. Chem. Phye., 1962, 36, 2676, 2681.so M. Schiavello and G. G. Volpi, J. Chem. Phys., 1962, 57, 1510.61 J. Kaplan, W. J. Schade, C. A. Barth, and A. F. Hildebrandt, C a d . J . Chem.,s*A. N. Wright and C. A. Winkler, Canad. J . Chem., 1962, 40, 5.6aF. Kaufman and J. R. Kelso, J . Chem. Phys., 1957, 27, 1209.84 J. T. Herron, J. Chem. Phys., 1961, 85, 1138.b6 R. A. Back end Y. P. Mui, J . Phys. Chem., 1962, 66, 1362.J. T. Herron, J. Phys. Cbm., 1965, 69, 2736.s7 N. A. A.Clyne snd B. A. Thrush, PTOC. Boy. Soc., 1961, A, 261, 269.1960, 88, 1688CAMPBELL AND THRUSH : DISCHABGE-PLOW SYSTEMS 23k17 == 3.0 x 101s exp (-200/RT) cm.3 mole-l sec.-l in a photometric study,in reasonable agreement with mass spectrometric values of (1.0 jc 0.5) x 1013and (5-07 -& 0.13) x 10l2 ~ m . ~ rnole-1 sec.-l by Herron 54 and by Phillipsand Schiff.68Other active species which might be present in the yellow afterglowinclude metastable N(2D) and N(2P) excited nitrogen atoms. Spectro-scopic 49 59 and mass spectrometric studies 60 have shown that these activespecies disappear rapidly, probably by wall deactivation.61 The wall decayof N(2.D) is inhibited by cooling to -195”c, when strong N, Second Positiveemission due to the combination of N(2D) + N(48) is produced.62 Theexcited nitrogen molecule in the A3&+ state is another metastable specieswhich exists in the afterglow.Its lifetime has been variously estimatedby a range of techniques; 0.07 seconds by e.s.r.,63 0.08 seconds by reactionwith ammonia,64 0.9 seconds from decay of its emission from a pulseddi~charge,~~ m. 1 second from its behaviour in active nitrogen at very highpressures,61 2.6 x 10-2 seconds from the intensity of the (6,O) band in theabsorption spectrum A3&+ +- XI&+ (ref. 66) and 2.0 -J= 0.9 seconds bycomparison of the intensities of its emission [ (0,6) Vegard-Kaplan] andabsorption spectra [ (1,O) First P0sitive].~7 Apart from the last two measure-ments, all these values are actual lives which are less than the radiativelife and depend on experimental conditions, since there is evidence thatN,(A3Eu+) is efficiently destroyed on the walls and by other species.61.68The discrepancy between the last two values which are rcldiative lifetimesis disturbing; if a more recent value of the life of N2(B3II,) is used,69Carleton and Oldenberg’s value 67 is increased by a factor of seven to15 seconds which widens the discrepancy; the v3 factor in the emissionprobability can only account for a factor of four between these values.Further work is clearly needed.Vibrationally excited ground-state nitrogen molecules have been detectedby heat release when nitrous oxide is added 70 and by vacuum-ultravioletspectroscopy, where populations of level v f f = 1 up to 10% of level wn = 0were observed.’l The antisymmetric stretch frequency of N,O is excitedby near resonance transfer from vibrationally excited nitrogen molecules.72The mechanism of the yellow afterglow has attracted considerableattention.It has been shown that emission in the near-infrared region58 L. F. Phillips and H. I. Schiff, J . Chem. Phys., 1962, 36, 1509.59 Y. Tanaka, A. S. Jursa, F. J. Leblanc, and E. C. Y . Inn, Planetary Space Science,6o S. N. Foner and R. F. Hudson, J . Chem. Phys., 1962, 37, 1662.61 J. F. Noxon, J . Chem. Phys., 1962, 36, 926.6 2 Y. Tanaka, F. J. Leblanc, and A. S. Jursa, J . Chern. Phys., 1959, 30, 1614.6s J. M. Anderson and J. N. Barry, Proc. Phya. Soc., 1961, 78, 1227.6 4 H. B. Dunford, E.R. V. Milton, and D. L. Whalen, C a d . J . Chem., 1964,6 5 E. C. Zipf, J . Chem. Phys., 1963, 38, 2034.6sP. G. Wilkinson and R. S. MuUiken, J . Chem. Phys., 1959, 31, 674.67 N. P. Carleton and 0. Oldenberg, J . Chern. Phys., 1962, 86, 3460.68 I. M. Campbell and B. A. Thrush, Proc. Chem. Soc., 1964, 410.69 M. Jeunehomme and A. B. F. Duncan, J . Chem. Phys., 1964, 41, 1694.‘OF. Kaufiaan and J. R. Kelso, J . Chern. Phys., 1958, 28, 510.71 K. Dressler, J . Chem. Phys., 1959, 30, 1621.72 E. L. Milne, M. Steinberg, and a. P. Broids, J . C h m . Phys., 1966, 42, 2615.1959, 1, 7.42, 250424 GENERAL AND PHYSICAL CHEMISTRYcomes from a newly discovered Y3&- state in addition to the familiarB3ng -+ A3&+ 74 Bayes and Kistiakowsky 75 have discussedthe mechanism in detail, dividing the bands into five groups; they proposedthat a steady state concentration of N,(5C,+) is the precursor of the emittinglevels assuming that the emission intensity was proportional to [N]2[M].Recent work shows that this relation only applies at low pressures,76 theintensity being independent of pressure above 1 mm. Hg.77 Campbell andThrush have recently summarised evidence on the pressure-dependenceof active nitrogen and have shown that the enhancement of the afterglowin argon or helium carriers is due to efficient quenching of N2(B3n,) byN,(X1&+). They conclude that N,(A3C,+) is the precursor of N2(B3n,)a,nd that about one third of the recombining molecules pass throughN,( B3rIg). Their value 78 for the luminescent rate constant in pure nitrogenis 7 x lo6 ~1111.~ mole-l sec.-l, in fair agreement with Young a,nd Sharpless'value 77 of 1.8 x lo7 ~111.~ mole-1 sec.-l.The rate constants for the three-body recombination of nitrogen atomshave been measured by several workers.The reaction was studied photo-metrically 19, 's and by mass spectrometry 79 using titration with nitricoxide to establish the absolute concentration of nitrogen atoms. The valuesgiven are for d[N,]/dt in cm.6 mole-2 sec.-l. Herron, Franklin, Bradt, andDibeler 79 obtained 5.7 x 1015 for M = N,, 2.8 x 1015 for M = Ar, and0.82 x 1015 for M = He, and these were independent of temperature in therange 195"-450"~, and agree with the relative efficiencies for bromine andiodine atom recombination.Mavroyannis and Winkler 8o found 1.06 x 10l6and Kretschmer and Petersen l9 obtained 8-0 x 1014, both for M = N2a t 300"~. Campbell and Thrush 78 have reported 1-38 x 1015 for N,,1.73 x 1015 for Ar, and 1.92 x lof5 for He at 298"~. The discrepanciesbetween these values may well be due to different methods of allowing forheterogeneous recombination.The short-lived pink afterglow of nitrogen was first reported by Bealeand Broida 81 in fast-flowing nitrogen at high pressures. The conditionsinvolved are somewhat unusual, since it can be preceded and followed bythe normal yellow nitrogen afterglow. It shows emission by species withenergies up to 22 ev above ground-state nitrogen molecules. These includeN(3s 2P), N2+(B2C,+), and N, First Positive and Second Positive emissionfrom levels above the dissociation limit into normal atoms.*, Absorptionstudies in the vacuum-ultraviolet region show ground-state nitrogen mole-cules with up to 20 quanta of vibrational energy 83 but no increase in theconcentration of atoms in the ground state (*X) or low-lying metastable73 K.D. Bayes and G. B. Kistiakowsky, J . Chem. Phys., 1958, 29, 949.7 4 F. J. Leblanc, Y. Tanaks, and A. S. Jursa, J . Chem. Phys., 1958, 28, 979.7 5 K. D. Bayes and G. B. Kistiakowsky, J. Chena. Phys., 1960, 32, 992.76 R. A. Young, R. L. Sharpless, and R. Stringham, J . Chem. Phys., 1964,41,1497.7 7 R. A. Young and R. L. Sharpless, J . Chem. Phys., 1963, 39, 1071.7'31. M. Campbell and B. A. Thrush, Chem. Comm., 1965, 250.7 9 J.T. Herron, J. L. Franklin, P. Bradt, and V. H. Dibeler, J . Chena. Php.,80 C . Mavroyannis and C. A. Winkler, Canad. J. Chem., 1961. 39, 1601.81 Q. F. Beale and H. P. Broida, J . Chem. Phys., 1959, 31, 1030.*2R. A. Young, J . Chem. Phys., 1962, 36, 3854.63 A. M. Bass, J . Chena. P h p . , 1964, 40, 696.1959, 30, 879CAMPBELL AND THRUSH : DISCHARGE-FLOW SYSTEMS 25states ( 2 0 and ") in the pink afterglo~.~4 The ion density is ca. 2 x 1O1Ocm.-3, which is about one hundred times greater than in the yellow after-gl0~;85 this explains efficient quenching by a 60 kc./sec. electric field.82Rag and Clark 85 suggest that N(6X) is the high-energy metastable speciesresponsible for the pink afterglow, but this was not detected in e.s.r.experiments.86 Young 82, 87 suggests a catalysed recombination of nitrogenatoms involving N,+ and N,+.have investigated the nitric oxide emission fromthe association of nitrogen and oxygen atoms.They show that the v' = 0level of NO(C2rl[) (6 bands) is populated by a two-body association andpostulate that NO(A2X+) ( y bands) is populated partly by radiation fromthe C state and partly by a pressure-dependent collisional mechanism.Formation of nitric oxide molecules in b4C- and B2II states also occursby a,n indirect collision-induced mechanism. Rate constants for the associa-tion of N and 0 with N, as third body have been measured as 1.85 x 1015mole-, sec.-l (ref. 80) and 3.3 x 1015 cm.6 mole-2 sec.-l (ref. 19) at300 OK.Young and SharplessThree recent studies of the reactionN +O,+NO + o (18)have yielded rate expressions of 1.7 x 1013 exp (-7500/RT) (ref.89)8.3 x 10l2 exp (-7200/RT) (ref. 57), and 2.3 x 10l2 exp (-5900/RT)cm.6 mole-, sec.-l (ref. go), all in good agreement with the value of2 x 10l2 exp (-6200/RT) found by Kistiakowsky and V01pi.~~ Agreementbetween the photometric value 9, (1.02 x 1010 cm.3 mole-1 sec.-l) and themass spectrometric 58 rate constant of (1.32 & 0.32) x loll ~111.~ mole-lsec.-l for the reactionN + O,-+NO + 0, (19)is less satisfactory. In this system catalysis by trace impurities of hydrogencan occur.The reaction of nitrogen atoms with nitrogen dioxide is more complex;the stoicheiometry shows that a t least three of the four possible initial stepsabN + NO,-+N,O + 0+NO +NO--+& + 0,+N2 + 2 0Cd84 C.E. Fairchild, A. B. Prag, and K. C. Clark, J. Chem. Phys., 1963, 39, 794.86 A. B. Pra.g and K. C. Clark, J . Chem. Phys., 1963, 39, 799.86 R. A. Young, R. L. Sharpless, and R. Stringham, J. Chem. Phys., 1964, 40,87 R. A. Young, C. R. Gatz, and R. L. Sharpless, J. Phys. Chem., 1965, 69, 1763.88 R. A. Young and R. L. Sharpless, Discuss. Faraday Soc., 1962, 33, 228.89 F. Kaufman and L. J. Decker, 7th Symposium on Combustion, Butterworths,90 C. Mavroyannis and C. A. Winkler, " Chemical Reactions in the Lower ands1 G. B. Kistiakowsky and G. G. Volpi, J . Chem. P h p . , 1957, 2'9, 1114.s 2 H. P. Broida, H. I. Schiff, and T. M. Sugden, Nature, 1960, 185, 759.251.London, 3959, p.57.Epper Atmosphere ," Interscience, New York, 1961, p. 28726 UENERAL AND PHYSICAL CHEMISTRYoccur, their relative proportions being independent of temperature. 93 Arecent mass spectrometric investigation 94 gives an overall rate constant of(1.11 & 0-12) x 1013 ~111.~ mole-1 sec.-l, and relative proportions ofa : b : c : d : : 0.43 : 0.33 : 0-10 : 0.13, in fair agreement with earlier work.93, 95The reaction of active nitrogen with bromine or hydrogen bromide givesorange NBr emission from near the walls of the vessel.96 It is probabletha-t NBr is formed heterogeneously and rapidly removed by reaction withnitrogen atoms.In contrast, the NS(B211 -+ X 2 n ) emission 97 from the reaction of activenitrogen with sulphur is confined to the centre of the flow tube, suggestingexcitation by a molecular species which is destroyed a t the walkgs Thesimilar beha,viour of emission by the CN impurity in active nitrogen hasbeen attributed to such a mechanism involving N2(A3Z,+) rather thanformation of excited CN in the catalytic recombination processN + CN + M-NCN + MN +NCN -+N2 + C NNS is apparently removed by nitrogen atoms; in their absence it can yieldN,S,, e k g 9The reaction between hydrogen atoms and nitrogen atoms gives NHemission i'rom levels v' = 0 and 1 of the A311 state as well as nitrogenFirst and Second Positive emission.100 Mannella lol has suggested that NHis excited by collision with N2(B3111,), v' = 12, but this species has a lifeof less than S ~ C .~ ~ and has no allowed vertical transition of sufficientenergy; his mechanism for the nitrogen Second Positive bands' excitation isN2(A3&+),p,6-9 f NH(ASII)~'=O + NH(X3C-) + Na(C 8n,)d = 0,lMany studies have been made of the reaction of nitrogen atoms withhydrocarbons. Linnett and Jennings1o2 have shown that, in addition tostrong CN red (A2n -+X2X+) and violet ( B 2 P -+X2X+) emission, thesereact'ions yield CH(2A), NH(311), C, Swan bands (from ethylene and acety-lene) and a spectrum now know to be due to NCN.lO3 The overall processesoccurring are clearly complex.Broida and co-workers 104-106 have studiedthe very strong CN emission from the reaction between active nitrogen andhalogenated hydrocarbons. They have shown that excited CN is producedpredominantly in high vibrational levels of the A211 state and that v' = 0level of the B22+ state is populated from A2II, v' = 10, by collision-93 M.A. A. Clpe and B. A. Thrush, Trans. Paraday SOC., 1961, 57, 69.Q 4 L. F. Phillips and H. I. Schiff, J . Chem. Phys., 1965, 42, 3171.95 F. Kaufman and J. R. Kelso, 7th Symposium on Combustion, Butterworths,9 6 E . R. V. Milton and H. B. Dunford, J . Chem. Phys., 1961, 34, 51.9 7 J. J. Smith and B. Meyer, J . Mol. Spectroscopy, 1964, 14, 160.g8 J. A. S. Bett and C. A. Winkler, J . Phys. Chm., 1964, 68, 2735.99 J. A. S, Bett and C. A. Winlrler, J. Phys. Chem., 1964, 68, 2501.London, 1959, p. 53.loo H. Guenebaut, G. Pametier, and P. Goudmand, Compt. rend., 1960, 251, 1480.Iol G. G. Dlannella, J .Chem. Phys., 1962, 30, 1079.lo2 J. W. Linnett and K. R. Jennings, Tram. Faraday SOC., 1960, 56, 1737.Io3 G . Herzberg and D. N. Travis, Canad. J . Phys., 1964, 42, 1658.I04 N. H. Kiess and H. P. Broida, 7th Symposium on Combustion, Butterworths,1O5 H. P. Broida and S. Golden, Canad. J. Chem., 1960, 38, 1666.I06H. E. Radford and H. P. Broida, J. Chem. Phys., 1963, 38, 644.London, 1959, p. 207CAMPBELL ABND THBUSH: DISCHARUE-FLOW 6YST1MS 27induced transitions between levels which are very near to resonance.Bayes,”o7 who studied CN red emission from the reaction of active nitrogenwith C,N,, HCN, ClCN, and CC1, showed that the vibrational distributionin this spectrum was the sum of two components, the P , arising from levels3 < v’ < 10 which corresponds to that described by Broida and thePI distribution where levels 0 < vr < 3 are populated.Setser and Thrush lo8showed that the P , distribution in the AZII state was accompanied bypopulation of higher vibrational levels (u’ > 5 ) of the B2Z+ state, whilethe P, distribution corresponded to population of level d = 0 of the B2Cfstate. These workers pointed out that the P, distribution is characteristicof reaction in which the CN linkage has to be formed and suggest that theexcited CN is produced in the reactionN + cx -+ x + CN(AQ,3 < v < 10)where X = H, C1, or Br. They also suggest that the PI distribution isdue to excitation of previously formed CN, either by metastable species orby CN acting as a third body. Brown and Broida 1°Q have suggested thatvery high vibrational levels of the A2II state (u‘ - 18) are precursors ofthe high vibrational levels of the B2X* state and suggest thatN + NCN --+ N, + CN”is the reaction responsible. Bayes 107 suggests that the P , distribution inthe CN red system is associated with the formation of excited CN in thedissociation of XCN.It seems unlikely that these processes would givethe observed excitations.09gen Atom.-Ground state (sP) oxygen atoms are readily producedby passing molecular oxygen through an electric discharge. They are easilydetected by the grey-green air afterglow emission caused by added nitricoxide. The intensity of this afterglow is proportional to [O][NO] and itprovides the indicator for Kaufman’s method of measuring oxygen atomconcentrations by titration with nitrogen dioxide.OfNO,+NO+O, (23)Krongelb and Strandberg 6 and Westenberg and de Haas 7 have determinedabsolute concentrations of O( 3P) by e.8.r.Vacuum ultraviolet absorptionspectroscopy is another method; Morse and Kadman have observedO(3P) but could not detect O(lD) or Q(W) in absorption in pure 0, or inthe presence of Ar, He, N,, or H,O. Emission by O(W) to O{lD), whichis the auroral green line at 5577 a, is observed when oxygen atoms areobtained by titrating active nitrogen with nitric oxide.61 This emissiondepends on the presence of nitrogen atoms 5l and the dominant excitationprocess is probablyN -I- N 4- 0 +N, 4- Ops)but some additional process giving an intensity proportional to the squareof the oxygen atom concentration must also participate.77 By comparisonof the intensity of the O(1S+3P) line at 2977 A with the auroral green linelo’ K.D. Bayes, Canad. J . Ohm., 1961, 39, 1074.lo8 D. W. Setser and B. A. Thrush, Proc. Roy. Soc., 1965, A, 288, 256.IoB R. L. Brown and H. P. Broida, J. Chem. Phys., 1964, 41, 2063.110 F. Kaufman, Proc. Roy. SOC., 1958, A , 247, 12328 GENERAL AND PHYSICAL CHEMISTRYNoxon has shown that collision-induced transitions must increase theprobability of the latter by a factor of about thirty.The general evidence is that excited oxygen atoms, unlike metastablemolecular species, are not an important constituent of discharged oxygen.Evidence for the presence of long-lived metastable oxygen molecules insuch systems came originally from mass spectrometric studies.1119112 Elias,Ogryzlo, and Schiff n3 showed that a detector coated with cobalt oxidecould detect a heat release after oxygen atoms had been removed by amercury mirror.These experiments suggested the presence of about 10%of O,( lA,). Such concentrations are confirmed by Noxon’s observation 114of its emission at 12,700 A and its detection with e.s.r. by Falick, Mahan,and Meyers.ll5Ogryzlo and his co-workers 116, 117 have shown that the broad emissionbands at 6340 A and 7030 A are due to concerted emission by two O,(lA,)molecules as an unbound complex. They deduce a radiative life of 2.5 x 10-3seconds for this process which is a factor of lo5 shorter than for a singleunperturbed 02(lA,) molecule.Their finding that the intensity of the‘‘ dimole ” emission is proportional to the square of 02(1Ag+3&-) emissionintensity at 12,700 was not confirmed by March, Fwnival, and Schiff>l*who obtained a first-power relation and suggested that the dimoles are alsoremoved by O,(lA,) possibly to yield 02(1Xff+). Young and Black 119 sug-gest that O,(lEg+) is formed from two 02(1Ag), although this process violatesspin conservation, since 02(3Cg-) must be the other product. O,(lA,) isnot significantly quenched by GO2, N20, N,, H,O, NO, Ar, He, CO, NH,,or HZ116 and only reacts slowly with ethylene.l15 It is not expected t obe highly reactive, as its excitation energy is only 22 kcal./mole.From the intensity of the atmospheric band emission at 7619 A Noxon 114concludes that the concentration of O2(lXC,+) in discharged oxygen is lessthan 1.07(,, in agreement with Clyne, Thrush, and Wayne,120* 12f who foundapproximately 0.1% of this species a t 1 mm.Hg pressure. Like 02(1Ag),this species is apparently mainly formed in the discharge, although it isless metastable, having a radiative life of 7 seconds. From experimentswhere oxygen atoms were prepared by titrating active nitrogen with nitricoxide, Young and Sharpless 77 showed that 02(lXg+) is a minor product ofoxygen atom recombination ; the absolute intensity of this emission foundwas 4 x lWO[0]2[MJ einsteins cm.4 sec.-l, collisional quenching beingnegligible up to 10 mm. Hg pressure of nitrogen.The concentrations ofO,(lZg+) produced were about 1% of those in discharged oxygen. As with02(1Ag), the emission spectrum of 02(1Zg+) shows that it is almost ex-ll1 S. N. Foner and R. L. Hudson, J . Chem. Phys., 1956, 25, 601.112 J. T. Herron and H. I. Schiff, Canad. J . Chem., 1958, 36, 1159.118 L. Elias, E. A. Ogryzlo, and H. I. Schiff? Canad. J . Chem., 1959, 37, 1680.ll* J. F. Noxon, Canad. J . Phys., 1961, 39, 1110.115 A. M. Falick, B. H. Mahan, and R. L. Myers, J . Chem. Phys., 1965, 42, 1837.11* L. W. Bader and E. A. Ogryzlo, Discuss. Furuduy Soc., 1964, 37, 46.S. J. Arnold, R. J. Browne, and E. A. Ogryzlo, Photochem. and Photob%oZ., 1965.118 R. E. March, S. G. Furnival, and H. I. Schiff, Photochem. and Plwtobwl., 1965.119 R. A. Young and G.Black, J . Chenz. Phys., 1965, 42, 3740.120 1%. A. A. Clyne, B. A. Thrush, and R. P. Wa-yne, Nature, 1963, 199, 1057.1z1R5. A. A. Clyne, B. A. Thrush, and R. P. Wayne, Photochern. and Photobiol.,1965, 4, 957CAMPBELL AND THRUSH : DISCHARGE-FLOW SYSTEMS 29clusively in the lowest vibrational level, which has an excitation energyof 37 kcal./mole. Thus it has sufficient energy to decompose ozone to O2and 0, a process which occurs quite rapidly.120* 118 The decomposition ofozone by 02(lAg) is 2 kcal./mole endothermic and probably has a rateconstant of -1 x 1010 cm.3 mole-1 sec.-l at room temperature.118 02(1X,+)is quenched by C02 and N20 77 but it is not strongly removed by NO,NO,, or O2.l2IOxygen molecules in the more highly excited metastable AS&+ statemust be formed by recombination rather than in the discharge, since thestate has a radiative lifetime of less than 0.1 second (Herzberg bands).The details of this process are not clear, but it does not appear to be animportant one .I22 9 7In assessing the following studies of oxygen atom reactions, it is im-portant to consider possible interference by the excited molecular speciesmentioned above.In the absence of molecular oxygen, oxygen atoms recombine by thereaction0 + 0 + M + 0 , + Mwhich has been studied a t room temperature by several groups. Harteckand Reeves 123 obtained a rate constant of 1-08 x 1015 cm.6 mole-2 sec.-lfor M = Ar and 0, in experiments where argon-osygen mixtures werepassed through a discharge.This is probably an upper limit, since theydid not allow for removal of oxygen atoms by other processes such assurface decay. Marshall 124 studied this recombination by e.s.r.and obtaineda rate constant of 1.35 x 1015 cm.6 mole-, sec.-l for M = Ar. For M = O,,Kaufman and Kelso 125 found a rate constant of (1.0 -J= 0.3) x 1015 cm.6mole-2 sec.-l. The most extensive study is by Morgan and Scl~ifT,l~~ whoproduced oxygen atoms in the absence of molecular oxygen by titratingactive nitrogen with nitric oxide to just past the end-point. They obtaineda rate constant of 1.01 x 1015 ~111.~ mole-2 sec.-l for M = N, a t roomtemperature (expressed as d[ 02]/dt) and gave the following relative efficienciesfor different third bodies:Ar : He : N, : N,O : GO, : SF, :: < 0-3 : 0.3 : 1.0 : 1.4 : 3.0 : 3.0The recombination of oxygen atoms in the presence of molecular oxygen0 + 0 2 + M + 0, + M (25)0 + 0, + 0, + 0, (26)is not only affected by excited oxygen molecules which can decomposeozone, but also by hydrogenous impurities which produce a hydrogen-atom-catalysed process with closely similar kinetics 110*20H + O2 + M -+ HO, + M (3)O + H O , + O H + O , (27)0 + OH+H + O2 (7)which occurs by the mechanismla* C.A. Barth and J. Kaplan, J. Mol. Spectroscopy, 1959, 3, 583.lasP. Harteck and R. R. Reeves, “Chemical Reactions in Lower and UpperAtmosphere ,” Interscience, New York, 1961, p. 219.lZ4 T. C. Marshall, Phys. Fluids, 1962, 5, 743.lZ5 F. Kaufxnan and J. R. Kelso, “ Chemical Reactions in Lower and Upper Atmo-sphere ,” Interscience, New York, 1961, p.255.lZ6 J. E. Morgan and H. I. Schiff, J. Chenz. Phys., 1963, 38, 149530 GENERAL AND PHYSICAL CHEMISTRYTo overcome these diiliculties Kauf'man and Kelso l a 7 produced oxygenatoms by flowing ozonised oxygen through a furnace at 100O"a Theyobtained a rate constant E25 of 2.7 x 1014 cm.6 mole-, sec.-1 for M = 0,in the subsequent recombination. Clyne, McKenney, and Thrush 128 passedargon containing minute amounts of oxygen through a discharge and addedmolecular oxygen downstream; they obtained E25 = 8 x 1012 exp (19OO/RT)cm.6 mole-2 sec.-l for M = Ar. In both studies the air afterglow was usedto measure oxygen atom concentrations and the studies agree very well ifthe relative efficiencies of molecular oxygen and argon are taken as 1.7 : I,the value found in the pyrolysis and photolysis of ozone,Studies of the reaction0 + 0, -3 0, + 0, (26)are also affected by the presence of excited oxygen molecules and byhydrogen atom catalysisH + O,+OH + 0,0 + OH+O, + HPhillips and Schif€68 report k26 = (1.5 &- 0.3) x 1O1O ~111.~ mole-1 sec.-lfrom a mass spectrometric study, whereas Mathias and ScW 129 obtainedk26 = 5.4 x lo9 ~111.~ mole-l sec.-l using mass spectrometry to determinethe steady-state ozone concentration in discharged oxygen, allowance beingmade for excited species.The latter value is in better agreement withstudies of the thermal decomposition of ozone.The reaction0 +NO + M - + N O , + Mand its associated air afterglow emission have been extensively studied.The rate constants obtained agree remarkably well 110,130-133 and onlycertain data are given. Clyne and Thrush 131 obtained k, = 9 x 1014 exp(+ 1800 & 400/RT) cm6 mole-2 sec.-l photometrically for M = 0, overthe range 212'-315'~ with relative third-body efficiencies ofHe : Ar : 0, : N, :: 0.58 : 0.87 : 0.87 : 1-0Klein and Herron 133 found it28 = (1.44 & 0.2) x 1016 exp (1930 &- 100/RT)cm.6 mole-a sec.-l mass spectrometrically for M = N,.Kaufman andKelso 132 give the following rate constants for various third bodies a t 3 0 0 " ~in units of cm.6 mole-2 sec.-l: He, 1.8 x 10l6; Ar,O,, 2.2 x 10ls;N2, 3.4 X lo1'; CO,,N,O, 4.7 X 1016; CH4,CF4, 5.0 X 10ls; SF6, 6.8 X 10l6;R20, 14.0 x lola.obeyed the relationKaufmanllo showed that the intensity of the air afterglow emissionI = I,[O]"O]~~ ~ ~la' F.Kaufman and J . R. Kelso, D.iscuss. Faraday SOC., 1964, 37, 26.lS8 M. A. A. Clyne, D. J. McKenney, and B. A. Thrush, Trans. Faradzy SOC., 1966,lSa A. Mathias and H. I. Schiff, Discuss. Paraday SOC., 1964, 37, 38.lSo E. A. Ogryzlo and H. I. SchZf, Canad. J. Chem,, 1959, 37, 1690.lS1 M. A. A. Clyne and B. A. Thrush, Proc. Roy. SOC., 1962, A, 269, 404.lSp F. Kaufman and J. R. Kelso, Symposium on Chemiluminescence, Duke Uni-lta F. S. K l e h and J. T. Herron, J . Chm. Phys., 1964, 41, 1286.61, 2701.versity, 1965CAMPBELL AND THRUSH: DISCHARGE-FLOW SYSTEMS 31and estimated the magnitude of I,. Although I , was independent of pres-sure over the range studied, Clyne and Thrush 131 showed that it dependedsomewhat on the nature of the carrier gas and varied with temperature asexp (+ 1500/RT). Fontijn, Meyer, and S ~ h i f f l ~ determined I, actino-metrically, obtaining 3.8 x lo7 ~ m .~ mole-l sec.-l at 300"~ for an oxygencarrier; they showed that the emission extends from about 3900 A to14,000 A with its maximum intensity at -6000 8.Broida, ScM, and Sugden 135 established that the air afterglow emissionhas banded structure near its short-wavelength Emit at 3975 A, and that itsapparently continuous nature at longer wavelengths arises from unresolvedoverlapping bands. They showed that I,, was independent of pressurebecause the rate-determining processes in the formation and removal ofeIectronically excited NO2 both involved the carrier gas; they proposed adetailed mechanism involving two excited states of NO,.By consideringdata on the quenching of the fluorescence of NO,, Clyne and Thrush 131showed that approximately half the recombination occurs via the emittingstate. New quenching measurements on the NO2 fluorescence and deter-mination of the I, for the corresponding carriers have led Kaufman andKelso132 t o the conclusion that between 50 and 90% of the recombinationoccurs via the emitting state. They also find that the quantity I, decreasesa t pressures around 100 p as predicted by the Clyne-Thrush mechanism.131Hartley and Thrush 136 have shown that these and other observations indi-cate that recombination occurs mainly into the ground state of NO, and thatrelatively free crossing occurs between the excited state and high vibrationallevels of the ground state.From experiments in the 1-2Op pressurerange, Harteck, Reeves, and Chace 137 conclude that the chemiluminescentcombination of 0 and NO is a two-body process. Doherty and Jonathan I38also found a second-order pressure dependence at low pressure where a third-order dependence would be expected, but they observed a dependence onthe nature of the carrier gas used. Experiments in which nitric oxide isreleased in the upper atmosphere suggest that there is a two-body radiativeprocess, but with its emission shifted to the red as compared with laboratoryexperiments at higher pressures.etc.etc.Ice and glasses. Investigations of water in the solid state have so farbeen relatively limited, but interest has revived in the past few years as it isrealized that the response of the solid, and the observation by electron-spinresonance and optical spectroscopy of stabilized intermediates, may beuseful pointers to equivalent occurrences in the liquid. The most interestingresults to date have been obtained with acid and alkaline glasses.Irradiation of glassy solutions of KOH or NaOH a t 7 7 " ~ gives rise totrapped electrons, 0- radicals, and small yields of H atoms.210-212 It hasbeen suggested that the production of the trapped transient species is largelydetermined by the physical state of the 212 and that the glassystate gives rise to higher yields than the polycrystalline state, in generalagreement with a new treatment of ion spurs in dipolar liquids a.nd solids.213On the other hand G(e-t) as measured in solid solutions of KOH or NaOHshows exactly the same smooth dependence on the concentration of OH-,even though the intermediate concentrations give rise to glasses with NaOHand crystalline solids with KOH.214 It is concluded that the only essentialrequirement for the observation of trapped species is a solution, and thatphysical state may not be very important.A limiting G(e-,) = 1.9 wasreached at high concentrations of OH-. Electron spin resonance measure-ments on solid solutions of different cations in H,O and D,O show that boththe cation and protons interact with the trapped electron, and are consistentwith delocalization of the electron over a radius of 3-4 from the centreof the trap.215Trapped electrons are not formed in sulphuric acid glasses because theconcentration of proton donors is too high.Nevertheless, by adding N,O205 T. J. Sworski, J . Arner. Chem. SOC., 1964, 86, 5034.206 T. J. Sworski, ref. 158, p. 263.207 C. Lifshitz and G. Stein, J . Chem. Phys., 1965, 49, 3330.208 A. Rafi and H. C. Sutton, Trans. Paraday SOC., 1965, 61, 877.E. Hayon, Tram. Paraday Soc., 1965, 61, 723.2 l o D. Schulte-Frohlinde and K. Eiben, 2. Nutzlrforsch., 1962, Ira, 445; 1963, 18a,99; B. G. Ershov, A. K. Pikaev, P. Y. Glazunov, and V. I. Spitsyn, Izuest. Akad. NaukS.S.S.R., Ser. Khim., 1964, 10, 1755.211 K.Eibon and D. Schulte-Frohlinde, 2. phys. Chenz. (Frankfurt), 1965, 45, 20.212 T. Henricksen, Radiation Res., 1964, 23, 63.21s R. Schiller, J . Chem. Phys., 1965, 43, 2760,214 L. Kevan, J . Chem. Phys., 1965, 69, 1081.215L. Kevan, J . Arner. Chem. SOC., 1965, 87, 1481COLLINSON : RADIATION CHEMISTRY 105or Fe2+ ions to the glass, evidence for the formation of mobile electrons(e-,) was obtained, giving C(e-J = 1.7 and G(H,) = 043.216 Again thedegree of crystallinity was found to be important, G(N,) from solutions ofN20 being larger in the glass, whereas G(H2) was constant. The effects ob-served by electron-spin resonance in acidic glasses containing a wide rangeof solutes have been interpreted in terms of reactions of mobile electronsand positive holes, which may initially exist in irradiated pure ice in anesciton-like bound216 F.S. Dainton and F. T. Jones, Trans. Paraday SOC., 1965, 61, 1681.217 P. N. Moorthy and J. J. Weiss, ref. 158, p. 1807. MOLTEN SALTSBy D. Inman and S. H. White(Clbemistry Department, IThe City University, London, E.C. 1)INTEREST in this field has rapidly expanded in recent years in parallelwith the increasing importance of high-temperature chemistry in moderntechnology. The practical applications have been reviewed.1 Although thistopic has not been covered before in this series, Reviews are availablewhich cover the literature up to 1964. Annual Reviews of molten-saltwork have appeared in the Russian literature since 1959. Two importantbooks on the subject have recently been p~blished.~ Bibliographies ofmolten-salt publications have been prepared.5The topic has also been featured at several international conferences[for example, 18th I.U.P.A.C.(Montreal, 1961) ; 7th I.C.C.C. (Stockholm,1962); 19th I.U.P.A.C. (London, 1963); 15th C.I.T.C.E. (London, 1964) ;1st Australian Conference on Electrochemistry (Sydney and Hobart, 1963)l.A discussion group has been organised in Great Britain. Gordon Conferenceson Molten Salts were held in 1959, 1961, 1963, and 1965 in the U.S.A.This report will mainly review the work carried out in 1965. The choiceof topics has necessarily been somewhat arbitrary. We shall survey thosetopics which, for other solvents, would be covered in reports on “ionassociation,” “ acid-base equilibria,” and ‘‘ electrode double-layer and elec-l1). Inman, New Scientist, 1965, 25, 220; R.Littlewood, British Chemical En-gineering, Oct., 1962: W. Sundermeyer, Angew. Chem. Infernat. Edn., 1965, 4, 222.a G. J. Hills, D. Inman, and L. Young, Proc. 8th C.I.T.C.E., 1956, 90; G. J. Jam,C. Solomons, and H. J. Gardner, Chem. Rev., 1958,58,461; “ Physico-Chemical Measure-ments at High Temperatures,” ed. J. O’M. Bockris, J. L. White, and J. D. Mackenzie,Butterworths, London, 1959; G. E. Blomgren and E. R. Van Artsdalen, Ann. Rev.Phys. Chem., 1960, 11, 273; H. Bloom and J. O’M. Bockris, in “Modern Aspects ofElectrochemistry No. 2,” ed. J. OW. Bockris, Butterworths, London, 1959;‘H. C. Gaurand B. B. Bhatia, J . Sci. I d . Res., India, 1962, 21, A , 16; R.W. Laity, in ReferenceElectrodes: Theory and Practice,” ed. D. J. G. Ives and G. J. Janz, Academic Press,New York, 1961 ; Yu. K. Delimarskii and B. F. Markov, “ Electrochemistry of FusedSalts,” Sigma Press, Washington, 1961; E. R. Van Artsdalen, in “ The Structure ofElectrolytic Solutions,” ed. W. J. Hamer, Wiley, New York, 1959; T. B. Reddy,Electrochem. Technol., 1963, 1, 325; H. C. Gaur and R. S. Sethi, J . Electroanalyt. Chem.,1964, 7 , 474; R. D. Reeves, Dim. Abs., 1965, 28, 118; J. D. Corbett, in “ Survey ofProgress in Chemistry,” ed. A. F. Scott, Academic Press, New York, 1964, Vol. 11;J. D. Corbett and F. R. Duke, in “ Techniques of Inorganic Chemistry,” ed, H. B.Jonassen, Interscience, New York, 1963, Vol. I ; G.J. Janz and S. C. Wait, Quart.Rev., 1963, 225; H. Bloom and J. W. Kastie, in “Non-aqueous Solvent Systems,”ed. T. C. Waddington, Academic Press, London, 1965; E. A. Ukshe, Uspekhi Khim.,1965,34,322; 0. J. Kleppa, Ann. Rev. Phys. Chem., 1965,16,187; G. Serravalle, Ricercasci. Rend., 1964,4, A, 549; A. F. Alabyshev, M. F. Lantratov, and A. G. Morachevskii,“ Reference Electrodes for Fused Salts,” Sigma Press, Washington, 1965; J. Lumsden,“ The Thermodynamics of Molten Salt Mixtures,” Academic Press, London, 1966.8 A. G. Morachevskii, Zhur. priklad. Khim., 1960, 33, 1434; 1961, 34, 1398; 1962,35, 1390; A. G. Morachevskii and B. V. Patrov, ibid., 1963, 38, 1374; 1964, 37, 1396;1965, 38, 2138.(a) “ Molten Salt Chemistry,” ed. M. Blander, Interscience, New York, 1964;( b ) “Fused Salts,” ed.B. R. Sundheim, McGraw-Hill, New York, 1964.6 G. J. Janz, Technical Bull. Series, Rensselaer Polytechnic Inst., Troy, NewYork., 1st edn., 1958; 2nd edn., 1961INMAN AND WHITE: MOLTEN SALTS 107trode reactions”; that is, we shall concern ourselves with the electro-chemistry of molten salts. Such important matters as phase diagrams,theories of pure molten salts, and electroanalysis may be incompletelycovered.Nitrates.--Becrtuse they are easily handled and have relatively low meltingpoints (cf. chlorides, sulphates, carbonates, silicates, etc.), inorganic alkaliand alkaline earth metal nitrates and their eutectic mixtures arc3 frequentlylstudied as examples of the molten state. The bulk properties such asdensity,6, 7 surface tension,* and conductance 6 , 7, 9 are well-established in many cases.Although the limit of electrochemical stability on the anodic side is theoxygen evolution process, the reduction of nitrate ions intervenes beforemetal deposition on the cathodic side (at least for the alkali metal andalkaline earth metal nitrates).This cathodic process may be at leastformally regarded as the reduction of the acid component NO2+ arisingfrom the acid-base dissociation of the anion :NO,- * NO,+ $- 0 2 -NO,+ i- 28 +NO,-Earlier work lo established the stoicheiometry of the overall nitrate reduc-tion process. Topol et aE.ll have disputed the reality of the species NO,+in nitrate melts on the basis of the results obtained by chronopotentiometryand linear sweep voltammetry in the NaN0,-KNO, solvent to which theyadded acidic and basic species. Their results suggest that the acid-baseequilibrium in the melt involves NO, rather than NOz+.On the otherhand, Brough and Kerridge l2 postulated the formation of NO,+ in account-ing for some metal reactions in fused nitrate media, Although NO,+ needonly have a transient existence in this context, its lifetime may tvell beenhanced in the presence of the acidic Li+ ions contained in their melts.Hladik and Norand l3 haye studied the reduction of NO,- and NO2- ionsin the LiC1-KC1 eutectic. The nitrate ions appear to be directly reduceda t the high temperatures ( > 350 “c) of their experiments, although the resultscould also be explained on the basis of a fast nitrate dissociation reactionprior to electron transfer.Small but significant quantities of NO,- ionshave been shown to be present in freshly fused NaN03-H;N0, melts byanodic voltammetry l4 and chronopotentiometry .15 The production of NO ,-6 G. J. Jam, A. T. Ward, and R. D. Reeves, Technical Bull. Series, RensselaerPolytechnic Inst., Troy, New York, 1964.J. P. Frame, E. Rhodes, and A. R. Ubbelohde, Trans. Farday SOC., 1959, 55,2039.C. C. Addison and J.@ N. P. Popovskaya, P. I. Protsenko, and A. F. Ehva, Zhur. rteorg. K h h ,1964, 9, 1211.lo G. J. Hills and K. E. Johnson, in “ Advances in Polarogmphy,” sd. I. Longmuir,Pergamon Press, 1960, vol. 111,982; J . Electrochem. SOC., 1961,108,1013; H. S. Swoffordand H.A, Laitinen, J . Electrochem. SOC., 1963, 110, 814.11L. E. Topol, R. A. Osteryoung, and J. H. Christie, J . EteCtrochem. Soc., 1965,San Francisco Programma, AbsGract No. 207.1% B. J. Brough and D. H. Kerridge, Inorg. Chem., 1965, 4, 1353.1s J. Hladik and G. Morand, Bull. XOC. chim. Frunce, 1965, 828.1 4 X. S . Swofford and 9. G. McComiek, Anulyt. Chm., 1965, 37, 970.1 5 D. Inman and J. Braunstein, Chem. Cmm., 1966, 148.Coldrey, J . Chem. Soe., 1961, 468108 GENERAL AND PHYSICAL CHEMISTRYis attributed to nitrate reduction by organic impurities and thermal decom-position. Duke and Kust l6 claimed to have genemted 02- ions in a nitratemelt by the reduction of 0, a t a platinum electrode, although Swoffordand McCormick l4 suggest that the 02- ions are formed by the reductionof the melt itself (see above).Bombi and Fiorani 17 have employed thelatter process to generate 02- ions in nitrate melts. Kust l8 used sodiumcarbonate as the source of oxide ions to confirm the E" values for theoxygen electrode reported earlier.16 Sodium carbonate was rejected 14 onthe basis of the incomplete dissociation of GO,,- ions in nitrate melts,although in Kust's work nitrogen purging of the melt would have driventhe reaction CO,,- 4 CO, + 0,- to completion. The E" values obtainedby this method agree to less than 0.3 mv with those obtained followingthe coulometric addition of 0,- ions. Geckle l9 has studied the effect onnitrate reduction of small quantities of water dissolved in the NaN0,-KNO,eutectic at 350"c using the rotating platinum disc indicator electrode anda controlled potential polarograph.The limiting current of the cathodicwave observed is proportional to the bulk concentration of H,O. Coulo-metry, visual observation and analysis of the melt, and mass spectrometryof the gases evolved from the melt were also employed to elucidate thereactions. He postulates that the reduction of NO3- to NO,- ions isinduced by the electroreduction of dissolved water which is subsequent.lyregenerated by a series of chemical reactions.Several workers have investigated the mechanisms of anodic reactionsin pure fused nitrates. Gupta and Sundheim 2o have examined the anodicreaction at a rotating platinum macro-electrode in molten silver nitrateusing both steady-state and fast-sweep voltammetry a t 238"~.Two steps,at +0.5 v and 3-0-9 v versus the Ag-Ag+ reference electrode, were observedin the current density-electrode potential plots. The process a t +0.5 v istransport-controlled. The reactant 02- ions arise from the dissociation ofNO 3- ions. The observed increase in concentration polarisation when acidicS,O,2- ions are added to the melt supports this view. The Tafel plot leadsto an na value of approximately 1.2 and thus to n = 2 and a = 0.6. Inaddition, they tentatively suggest that the ni5rate ion uizdergoes directelectron transfer at +0.9 v to give an NO, zadicml which then decomposes;na for this reaction was found to be 0.9. On interrupting the polarisingcurrent they found that a steady potential was reached within a few milli-seconds.Arvia and his co-workers have observed similar steady potentialsfor silver nitrate21 and sodium They interpret these results interms of reversible cells of the typeM 1 MNO, 1 NO,,NO,O, (Pi) M = Ag,&Cell e.m.f.s calculated from the thermodynamic data agree with the steadyF. R. Duke and R. N. Kust, J . Amer. Chern. SOC., 1963, 85, 3338.l7 G. G. Bombi and M. Fiorani, Talanta, 1965, 12, 1053.I*R. N. Kust, J . Phys. Chem., 1965, 69, 3662; Inorg. Chern., 1964, 3, 1035.l9T. A. Geckle, U.S. A.E.C. TID. 21511, 1965 (Chem. Abs., 1965, 63, 9455).2o N. Gupta and B. R. Sundheim, J . Electrochem. Soc., 1965, 112, 836.21 W. E. Triaca and A. J. Arvia, EZectrochim. Acta, 1964, 9, 919.A. J.Arvia, A. J. Calandra, and W. E. Triaca, Electrochim. Ada, 1964, 9, 1422INMAN AND WHITE: MOLTEN SALTS 109potentials obtained experimentally. Baraboshkin et u Z . , ~ have calculatedexchange currents for silver electrodes in molten silver nitrate in the tem-perature range 220-350" c from their earlier observations 24 of the formationof silver crystal nuclei on platinum during the electrolysis of silver nitrate.The exchange currents for silver electrodes in fused salts have also beenmeasured.25 Triaca and Arvia 26 have made a detailed investigation of theanodic reaction occurring on bright platinum during the electrolysis of moltennitrates containing silver ions, over a temperature range from 220 to 470"c.The processes are temperature-dependent.In the range 220-29O"c twoconsecutive Tafel slopes of 2 R T/F and R T/F were observed. Two potential-dependent rate controlling steps are proposed to explain these results.Above 350"c the Tafel slope is RTIF. At the higher temperatures therate of decomposition of the nitrate ions is presumably high enough tomaintain a finite concentration of 0 2 - ions at the electrode surface; thus,the direct discharge of this ion is maintained at all potentials. At the lowertemperatures the direct discharge of nitrate ions may also occur (see twoTafel slopes observed). These authors 27 have also published a preliminaryaccount of their studies of similar anodic reactions on graphite. Thesereactions are observed to be temperature-dependent.In a series of papers, Delimarskii and Shilina 28 report the cathodicreduction at a rotating platinum disc-electrode of the halogens formed insitu by reaction of the LiN0,-NaN0,-KNO, eutectic with small quantitiesof added halides.They determined the solubility, diffusion coefficient andits temperature dependence, and the thickness of the diffusion layer foreach of the halogens Cl,, Br,, and I,. The supporting electrolyte exhibiteda wave on the electrode potential-current density curve a t -2.6 v versusa massive platinum quasi-reference electrode which they attributed to thereactionNO,+ + e + NO,However, Hills and Johnson, and Swofford and Laitinen had earlier 10reported waves in nitrate melts a t much less negative potentials. Swoffordand Propp 29 have investigated the anodic oxidation of bromide and iodideions in the KN03-NaN03 eutectic a t a rotating platinum micro-electrodeat 250"~.The previously 2 s v 54 observed oxidation of halide ions by thenitrate melt is thus probably related to the acidic nature of the Li+ ionswhich increases the oxidising power of the nitrate ion. Reversible one-electron waves were obtained. The E" values for the reversible reactionsX, + 2e s 2X-are +0.126 & 0.005 v for iodine-iodide and f-0.644 & 0.010 v for bromine-23 A. N. Baraboshkin, L. T. Kosikhin, and N. A. Xaltykova, DoElady Akad. NaukS.S.S.R., 1965, 160, 145.24 A. N. Baraboshkin, L. T. Kosikhin, and N. A. Saltykova, Doklady Akad. NaubS.S.S.R., 1964, 155, 880.26 Yu. K. Delimarskii, E. V. Panov, and A.V. Gorodyskii, Ukrain. khim. Zhur.,1965, 31, 782.28 W. E. Triaca and A. J. Arvia, Electrochim. Acta, 1965, 10, 409.2 7 W. E. Triaca and A. J. Arvia, Electrochim. Acta, 1965, 10, 973.28 Yu. K. Delimarskii and G. V. Shilina, Electrochim. Acta, 1965, 10, 973; Ukrain.2B H. S. Swofford and J. H. Propp, Analyt. Chem., 1965, 37, 974.khim. Zhur., 1964, 30, 1045; G. V. Shilina, ibid., 1963, 31, 693110 GENERAL AND PHYSICAL CHEMISTRYbromide versus their Ag-Ag+ reference electrode. Novik and Lyalikov's 3*proposal that the reaction2KI + KNOs + KNO, + K,O + I,accounts for the increase in the limiting current of the nitrite oxidationwave upon addition of KI to this nitrate melt is thus shown to be incorrect.Swofford and Holifield31 have recently published a study of the anodicoxidation of halide ions in the molten sodium nitrate-potassium nitrateeutectic a t a dropping-mercury electrode.The oxidations were irreversibleand the processes rather complicated. The mercury itself is not inactive;the formation of insoluble mercury halides and their subsequent dispersalalong with adsorption phenomena certainly play a part in the overall processa t the anode. Delimarskii and Shilina 32 have examined the polarographicbehaviour of thallium ions in the LiN0,-NaN08-KN03 eutectic at 160"~.They calculate a diffusion coefficient of 7.55 x 10-6 cm.2 sec.-l from theirresults. Swofford and Holifield s3 have investigated the electroreduction ofTl+, Cd2+, and Pb2+ ions at a dropping-mercury electrode in the moltensodium nitrate-potassium nitrate eutectic.T1+ and Cd2+ ions gave reversiblepolarographic waves but the reduction of Pb2+ ions was apparently rathercomplicated. Two waves were observed a t the higher Pb2+ ion concentra-tions employed. The latter results are inconsistent with those of earlierworkers34 who employed nitrate melts containing Li+ ions a t lower tem-peratures. The possible significance of surface phenomena is discussed.Chronopotentiograms 34c for Pb2+ ions in NaN03-KN03 also exhibited twosteps a t high Pb2+ ion concentrations. The second step was tentativelyascribed to the electroreduction of lead oxide formed rapidly on the hangingmercury drop surface after the initial deposition of lead.The thermodynamic properties of solutions of AgNO, in mixtures ofalkali metal and alkaline earth metal nitrates have been determined frommeasurements of the e.m.f.s of cells with transferen~e.~~ Most of the systemsshow almost ideal behaviour. For AgNO, in RbNO, the activity coefficientis less than unity.An interpretation in terms of complex-formation issuggested. The plots of e.m.f. versus the logarithm of the reciprocal ofthe AgNO, mole fraction for the Rb-Ca, Na-Ba, and K-Ca nitrate solventsexhibit temperature-dependent inflections. (This could be interpreted interms of changes in the gross ionic associations of the solvent melt.)Murgdescu and Topor36 propose a form of ion-pairing to account forthe comparable mobilities observed for lithium ions and the proper alkalimetal cations during the electromigration of Lif ions through alkali metalnitrate solvents.The inversion of the relative mobilities of the alkali metalcations at a specific temperature and composition has been observed in30 R. M. Novik and Yu. S. Lyalikov, Zhur. analit. Khim., 1958, 13, 691.3lH. S. Swofford and C. L. Holifield, Analyt. Chem., 1965, 37, 1513.32 Yu. K. Delimarskii and G. V. Shilina, Elektrokhimiya, 1965, 1, 632.33 H. S . Swofford and C. L. Holifield, Analyt. Chern., 1965, 37, 1509.34 (a) N. Nachtrieb and M. Steinberg, J . Amy. Chem. Soc., 1950, '92, 3558; (b) J. H.Christie and R. A. Osteryoung, ibid., 1960,82, 1841; (c) D. Inman and J. O'M. Bockris,J . Electroanalyt. Chem., 1962, 3, 126.35 M. Bakhs, d. Guion, and J. P. Brenet, EZectTochim.Ada, 1965, 10, 1001.313 I. G. Murgulescu and D. Topor, Rev. Roumaine China., 1964, 9, 815INMAN AND WHITE: MOLTEN SALTS 111LiN03-KN03 mixtures by Chemla and Lantelme.37 However, the diffusioncoefficients 38 are in the order DLi+> DN&+ > D K + and are independent oftemperature and composition. The anion-cation interactions proposed toexplain these results have been discussed quantitatively using a form ofthe Nernst-Einstein equation. Some transition metal ions dissolved invarious molten nitrate solvents have been titrated conductometrically withhalide ions.39 Density and conductance data for the pure solvents havealso been reported. The conductance data do not compare well with data,reported for similar systems.4* Duke and King using a d.c.techniqueobtained results for KN03 which are in excellent agreement with those ofAngell41 who employed the a.c. method. It is suggested that these datacould be used for cell calibration, thus eliminating the use of aqueous stan-dards. Bredig,42 in criticising the work of Papaioannou and Harrington,39has pointed out errors in calculation and the incorrect choice of system fortheir proposed model to explain the large decrease in conductance on addingKBr. Bredig suggested that the startling effects observed may be artifactsof the system. However, as evidenced above, the presence of Li+ ions innitrate melts often leads to unusual effects, so further experimental investiga-tion of these systems under well-controlled conditions seems desirable.In recent years, the problem of whether complexes are present in moltensalt solutions has been the subject of many studies.These experimentalinvestigations may be divided into two groups, those which provide directevidence, e.g., spectroscopy and ionophoresis, and those which provideindirect evidence, e.g., potentiometry, polarography, chronopotentiometry,double-layer capacity measurements, etc. In the former group, the spectro-scopic techniques which have been used up to the present cannot alwaysdistinguish between the transient near-neighbour ion-ion interactions chaxac-teristic of these systems, and any discrete kinetic entities which may bepresent. These are best distinguished on a lifetime basis, although therelaxation times ( 10-11-10-12 sec.) of conventional u.v., visible, and i.r.spectroscopy are too short to effect this separation.The n.m.r. techniquemay provide a solution of this problem. The appearance of a new discreteband, which is not present in the solvent, in the Raman spectrum of themolten salt solution is strong evidence for comp1ex-formation.*~ The iono-phoretic technique may be used to deduce the presence of long-lived entities.Ni2+ ions move in the cathodic direction in the LiC1-KC1 eutectic.44 Thus,any discrete chloro-nickel complexes must be sufficiently short-lived for thegross movement of nickel to be towards the cathode. Co2+ ions wereobserved to move in the anodic direction,45 so species such as [COC~,](~-~)+37 31. Chemla and F. Lantelme, Electrochim.Acta, 1965, 10, 663.38 F. Lantelme and M. Chemla, Compt. rend., 1964, 258, 1484.39 P. C. Papaioannou and G. W. Harrington, J . Phys. Chem., 1964, 68, 2424, 2433.40 F. R. Duke and L. A. King, J . Electrochem. SOC., 1964, 111, 712.C. A. Angell, J . Electrochem. Soc., 1965, 112, 956; J . Phys. Chem., 1964, 68,4 2 M. A. Bredig, J . Phys. Chem., 1965, 69, 1753.43 For example, see J. K. Wilmshurst, J . CJwm. Phys., 1963, 39, 1779; D. E. Irisha*nd T. F. Young, ibid., 1965, 43, 1765; W. Bues, 2. anorg. Chem., 1955, 279, 104;H. Bloom and J. O'M. Bockris, ref. 4b.44 G. Alberti, S. Allulli, and G. Modugno, J . Chromatog., 1964, 15, 420.45 G. Alberti, G. Grassini, and R. Trucco, J . EZectroanalyt. Chem., 1962, 3, 283.1917112 GENERAL AND PHYSICAL CHEMISTRY(where n > 2) must be long-lived.Ion-exchange measurements 46 for Ni2fand Go2+ ions in melts also support these observations. A quantitative evalua-tion of this type of measurement has so far not been formulated. At present,the existence of a definite complex species is best decided on the basis ofevidence from several independent techniques. Gruen has reviewed thespect,roscopy of transition metal ions in nitrate^.^^ 47 The change in wave-length of the absorption band of Co2+ in the molten LiNO,-KNO, eutecticat 1 6 0 " ~ on addition of chloride ions hams been interpreted in terms of theformation of a tetrahedral chloro-complex. Tananaev and Dzhurinskii 48reported similar shifts. They interpret these in terms of the step-wiseformamtion of CoC1, and [ CoCI,]- before tetrahedral [ CoC1, ] 2 - .Padova andhis co-workers 49 have obtained density and spectroscopic data for neody-mium nitrate dissolved in the NaN0,-KNO, eutectic. The sharp changein the temperature coefficient of density at 131 together with large changesin molar volume in more dilute solutions suggest that the species presentin solution are concentration-dependent. This confirms their earlier spectro-scopic work.5o Baddiel, Tait, and Janz 51 have investigated the Ramanand i.r. spectra of pure molten silver nitrate a t 250"~. The splitting ofthe degenerate stretching vibration of NO,- observed indicates strong ion-ion interactions. Cigdn and Mannerstrand 52 have determined the solubilityproduct of AgBr and the stability constants of various bromo-complexes,by solubility and e.m.f.measurements. The latter measurements showfhat the Nernst equation is valid for the Ag-Agf electrode in their nitratesolvent over the concentration range 10-1-10-5 mole kg.-l. However, thevalidity of their results must be doubted as they obtained their stabilityconsDants from the e.m.f.s of cells where the Ag+ ion concentrations were102-103 times lower than mole kg.-l. The applicability of the Nernstequation in this concentration range was not established. Arnikar, Sharma,and Tripathi 53 have investigated Ag-Ag + concentration cells with trans-ference in molten KNO,, NaNO,, and their eutectic mixture, and show theliquid junction potential to be negligible in the concentration range examined.They determined the solubility product of silver chloride in the various nitratesolvents using NaCl and CdCl, as titrants.Ks was found to be independent'of the composition of the solvent media. They also calculate a degree ofdissociation for CdC1, (ctCdC12 = 0.65 if ctsaC1 = 1) and attribute this tocomplex-formation. Bombi, Fiorani, and Mazzocchin 54a have argento-metrically titrated halides and cyanides in the LiN03-KN0, eutectic a t150 Oc ; the titrations were monitored by potentiometry, bipotentiometry,and biamperometry. The solubility products and a stability constant for413 G. Alberti, A. Conte, and S. Allulli, J . Chromatog., 1965, 18, 564.4 7 D. M. Gruen, Quart. Rev., 1965, 349.48 I. V. Tananaev and B.F. Dzhurinskii, Doklady Akad. NauE S.S.S.R., 1960,49 J. Padova and J. Soriano, J . Chem. and Eng. Data, 1964, 9, 510.50 J. Padova, 19th I.U.P.A.C., 1963, Abstract No. B3-6.61 C. B. Baddiel, M. J. Tait, and G. J. Jam, J . Phys. Chem., 1965, 69, 3634.5 2 R. Cigen and N. Mannerstrand, Acta Chem. Scand., 1964, 18, 2203; 1755.53 H. J. Arnikar, D. K. Sharma, and R. Tripathi, Indian J . Chem., 1965, 3, 7.64 (a) G. G. Bombi, M. Fiorani, and 0. A. Mazzocchin, J . Electroanalyt. Chem.,134, 1374; 1960, 135, 94; 1961, 139, 120; 1961, 140, 374.1965, 9, 457; ( b ) H. S . Swofford, Analyt. Chem., 1965, 37, 610INMAN AND WHITE: MOLTEN SALTS 113[AgCNJ- were calculated. CN- and I- ions are both unstable in thissolvent, which contains Lif ions. As discussed above, this can be relatedto the acidic nature of the Lif ion.Swofford54b has titrated halide ionsin the NaN0,-KNO, eutectic a t 250"~. Bornbi and Fioranil7 have in-vestigated the acidic nature of various cations in the NaN0,-KNO, eutecticusing a Pt-0, indicator electrode to monitor 0 2 - ion concentrations duringthe titration of the cations by 0 2 - ions generated in situ by the electro-reduction of NO,- ions at a Pt cathode. Cd2+, Co2+, Hg2+, Mg2+, &In2+,Ni2+, Pb2+, and Zn2+ ions gave stable nitrate solutions, but of these onlyCd2f and Zn2f ions gave sharp inflexions, evidencing their relatively strongacid nature. Tien 55 has determined the stability constants B1 and B2 forsilver cyanide complexes in the NaN0,-KNO, eutectic at 248" c using a,gallium-in-glass reference electrode.The Agf and CN- ion concentrationswere such that no precipitation occurred. The p-values do not agree withthose of earlier ~ o r k e r s . ~ ~ - ~ * Binuclear complexes were shown to be absent.Chamberlin 59 has calculated stability constants for silver chloride complexesin molten potassium nitrate from polarographic data, using a modificationof the DeFord and Hume 6o method. Inman 61 has reported stability con-stants for the chloro- and bromo-complexes of cadmium in the moltenNaN0,-KNO, eutectic at 250"c. An electrode of the third kind, reversibleto Cd2f ions, to monitor the changing metal-ion concentration duringtitration with KCI and KBr was established. The e.m.f. data were usedto calculate successive stability constants for these systems using the methodpublished earlier.62 The stability constants are compared with those deter-mined by other methods and discussed in terms of the co-ordination ofCd2f ions in nitrate melts.Narayan and Inman 63 have described theapplication of current-reversal chronopotentiometry to the investigation ofmetal ions dissolved in molten nitrates where the metal produced by cathodicreduction is oxidised by the solvent. Schlegel 64 has continued the studyof acid-base reactions in molten nitrates with an investigation of thedichromate-chlorate system in the presence of excess chloride. TheequilibriumCr,0,2- + C10,- + C10,+ + 2Cr0,2-is followed by the slow stepThe equilibrium constant ( K ) at 250"c is 1-6 x 10-lo mole kg.-l and therate constant (k) 0.208 kg.mole-l min.-l These values are compared withthose established earlier for nitrate-dichromate 65 and bromate-dichromate.66xkc10,+ + c1- + c1, + 0,65 H. Ti Tien, J . Phys. Chem., 1965, 69, 3763.66 S. N. Flengas and E. Rideal, Proc. Roy. SOC., 1956, A , 233, 443.57D. L. Manning and M. Blander, Inorg. Chem., 1962, 1, 594,68 J. Jordan and J. Prendergrast, Proc. 7th I.C.C.C., 1962, 102.59 J. Chamberlin, Diss. Abs., 1964, 25, 2749.6o D. D. DeFord and D. N. Hume, J . Amer. Chem. Soc., 1951, 73, 5321.61 D. Inman, Electrochim. Acta, 1965, 10, 11.szD. Inman, I. Regan, and B. Girling, J . Chem. SOC., 1964, 348.s3 R. Narayan and D. Inman, J. Polarog. SOC., 1965, 11, 27.134 J. Schlegel, J . Phys.Chem., 1965, 69, 3638.6 5 F. R. Duke and S. Yamamoto, J . Amer. Chem. SOC., 1959, 81, 6378.66 F. R. Duke and E. Shute, J . Phys. Chem., 1962, 66, 2114114 GENERAL AND PHYSICAL CHEMISTRYNokhosoev and Aleikina 67 have shown that chlorides and dichromatesreact a t temperatures greater than 400"c. Shams El Din and his CO-workers 68 continue their potentiometric studies of acid-base reactions inmolten salts. They have shown that the reaction between chromic oxideand molten potassium nitrate is2Cr0, + 2N0,- -+ Cr,O,*- + N,O, --+ 2N0, + &02with an activation energy of 25.3 kcal. mole-l. Paul and Dev 69 haveexamined the nature of Lewis acids in molten acetamide. A review ofacid-base and redox reactions in ionic melts has appeared.70 Courmert,Porthault, and Merlin 71 have studied the acid properties of some condensedphosphates in alkali metal nitrates at 350"c using the technique developedby Shams El Din.72 Sodium and trisodium orthophosphate were used asreactive bases.The results are in accord with the relative acid strengthsfound for condensed phosphates in the solid state. Courgnaud and Tr&millon 73 have investigated acid-base a,nd electrode reactions in moltencalcium nitrate te trahydrate .Halides.-Fluorides. They are highly corrosive and consequently difEcultto handle, but nevertheless a considerable amount of information on themis available. They are very important industrially in metal-winning, -plating,and -forming. The system NaF-AIF', has been extensively studied becauseof its importance in the aluminium industry.The nuclear reactor at OakR'idge which employs a molten fluoride reactant 7* has also necessitated alarge number of fundamental studies of these systems.75Their use as electrolytes for the electrodeposition of the transition metalsof Groups IVA, VA, and VIA has recently been reported. 76 Previous attemptst o deposit these metals from aqueous, non-aqueous, and other molten saltsystems in general either failed or gave rise to non-coherent or dendriticdeposits. The deposition of niobium from a solution of KF (26.2 wt. yo),LiF (10-5 wt. %), NaF (47.0 wt. %), and K2NbF7 (16.2 wt. yo) at 775"cand a current density of 50 ma ~ r n . - ~ has been reported.76 The importantvariables are temperature, valency state, and impurity level. Substantiallypure fluorides are required, and an explanation is advanced in terms ofcomplex ions of the appropriate stability for reduction at the cathode.The effect of the specific adsorption of impurity anions (e.g., chloride) ORthe electrode double layer may also be an important factor.77 Chrono-67 M.V. Mokhosoev and S. M. Aleikina, Zhur. neorg. Khim., 1964, 9, 1684.6BA. M. Shams El Din and A. A. El Hosary, J. Electroanalyt. Chem., 1965, 9,349; A. M. Shams El Din, A. A. El Hosary, and A. A. A. Gerges, ;bid., 1964, 8, 312.6 Q R. C. Paul and R. Dev, Indian J. Chem., 1965, 3, 315.7 O I. Slama, Chern. listy, 1965, 59, 792.7 1 N. Courmert, M. Porthault, and J. C. Merlin, Bull. SOC. chim. France, 1965, 910.78 A.M. Shams El Din, Electrochim. Acta, 1962, '7, 285; A. M. Shams El Din, A. A.7 3 R. P. Courgnaud and B. T. Trhillon, Bull. Soc. chim. France, 1965, 752; 758.74 W. R. Grimes, Nuclear News-A.N.S., May, 1964, 3.75 E.g., M. Blander, W. R. Grimes, N. V. Smith, and G. M. Watson, J . Phys. Chem.,1959, 63, 1164; 5. P. Young, Analyt. Chem. Div. Ann. Progr. Report, O.R.N.L. 3243,Dec., 1961; S. Cantor, R. F. Newton, W. R. Grimes, and F. F. Blankenship, J. Phys.Chem., 1958, 62, 96: K. Grjotheim, 2. phys. Chem. (Frankfurt), 1957, 11, 150.76 G. W. Mellors and S. Senderoff, J. Electrochem. SOC., 1965, 112, 266.77 A. D. Graves and D. Inman, Ekctroplating and Metal Finishing, in the press.El Hosary, and A. A. A. Gerges, J. Electroaaatyt. Chem., 1963, 6, 131INMAN AND WHITE: MOLTEN SALTS 115potentiometric measurements 7s have been made on dilute solutions10-4 mole kg.-1) of potassium fluorotantalate in the LiF-NaF-KF eutectiobetween 650 and 850"c to obtain a better understanding of the mechanismsinvolved in metal deposition in these systems.The reduction of quh-quevalent tantalum occurs by a two-step process which may be writM[TaF,I2- + 38 + TaF,(s) + 5F-andTaF,(s) + 28 --+ Ta, + 2F-The first step is diEusion-controlled, as charge transfer is rapid. Thediffusion coefficient for the [TaF7J2- ion is 1.5 x cm.2 sec.-l a t 750°c,and the activation energy between 650 and 800"~ is 8.5 kcal. mole-l.The low value of the diffusion coefficient and the high activation energyare consistent with a highly co-ordinated species such as [TaF,]".Thesecond step is not diffusion-controlled and poorly understood. Mellors andSenderoff 7 9 have indicated that the sexivalent fluorides of tantalum andniobium can be prepared by the electrolysis of molten alkali metal fluoridescontaining the quinquevalent ions using an inert anode. The oxidationprocess has been studied by chronopotentionietry. The latter authorshave also measured the densities and surface tensions of the systems LiF-Nap-ZrF, and LiF-KF-ZrF4. Plots of surface tension uemus log CzrpFIgive straight lines with inflections at concentrations corresponding to thestoicheiometries of complex compounds. The strength of the complex ionsis less in LiF-NaF-ZrF, than in LiF-KF-ZrF8, The presence of [ZrF7]3-is postulated, but [ZrF,J2-, the most stable configuration in the solid, isabsent in the melts containing sodium ions.The decrease in strength ofthe complexes in La-NaF-ZrF, may be due to the presence of the morehighly polarising Naf ion. Polishchulr 81 has measured the electrical con-ductivities of the ICF-KBF,-3K2ZrF6/2B 203 system. The temperaturedependence of electrical conductivity indicates an ionic structure and alsoa change in melt structure which is interpreted in terms of the formationof [ZrF,I3- ions. Sheiko et aLS2 have examined the anodic dissolution ofzirconium in fluoride and mixed fluoride-chloride melts at 800"c over arange of current densities. ZrF2 is found t o be insoluble in 60 mole yoKF40 mole yo NaF, but in mixed melts an exchange reaction occurs givingZrC1, (see also Smirnov and Kudyakov 83), The products of anodic dis-solution and corrosion are found in the anodic sludge where zirconium isfound in the bivalent form.Investigation of the fundamental processesinvolved in the winning of aluminium continue t o receive attention. Pion-telli and his co-workers s4 have investigated anodic phenomena at carbon7a S . Senderoff, G. W. Mellors, and W. J. Reinhart, J . Electrochem. SOC., 1965,112, 840.7 9 G. W. Mellors and S. Senderoff, J . Ekctrochem. Soc., 1965, 112, 642.G. W. Mellors and S. Senderoff, Proc, 1st Australian Conference on Electro-chemistry, Pergamon Press, New York, 1964, 578: J . Electrochem. Soc., 1964, 111, 1366.P. A. Polishchuk, Z h u ~ . neorg.Khim., 1964, 9, 921.8p I. N. Sheiko, T. N. Grechina, and V. T. Barchuk, Ukruin. khim. Zhur., 1964,80, 1055.88 M. V. Smirnov and V. Ya Kudyakov, Zhur. neorg. Khim., 1965, 10, 1211.€2. Piontelli, B. Mazza, and P. Pederferri, Electrochim. Acta, 1965, 10, 1117;Atti. Accad. w z . Lincei, Rend. Classe Sci. $8. mat. nut., 1964, 37, 3116 GENERAL AND PHYSICAL CHEMISTRYelectrodes of varying shapes and sizes in cryolite melts containing variousconcentrations of aluminium oxide. Mergault and Jacoud, 85 continuingearlier studies, have determined the quantity of electricity necessary toproduce the anode effect in cryolite solutions containing B203, SiO,, Tho,,La&,, Fe2O3, Cr203, Nb205, Ta205, CeO,, TiO,, and ZrO, at 1025"~ a t acurrent of 10 A for various concentrations of oxygen in the bath.The oxideswere classified into four groups according to their behaviour. Rey 86has investigated two cells of the typeA1 I Al,O,,cryolite I 0, and 0, I Al,O,,cryolite I C.The back-to-back combination of these cells represents the aluminiumelectrolysis cell. The experimental e.m.f.s are compared with those cal-culated from thermodynamic data for these systems. The formation ofoxide complexes of carbon adsorbed on the carbon electrode followed bytheir slow evolution is proposed to explain the time dependence of thee.m.f. of the cell 0, I Al,O,,cryolite I C. Pizzini and Agace 87 have measuredanodic and cathodic polarisations on lead electrodes in molten PbF,-NaFbetween 600 and 800"~ using the galvanostatic and potential sweep tech-niques.Passivation is important a t lead anodes in these melts if tracesof oxide impurities are present. Pizzini and Morlotti 88 have studied thecathodic evolution of hydrogen from LiF-NaF-KF melts contaminatedwith water by polarisation as a function of current-density measurements.They assume that hydrolysis leads to dissolved HF from which hydrogenis deposited according toHF +e--+*H, +F-They also assume that the HF is present in the melt as the complex [HE',]-,the slow dissociation of which to give HF determines the measured rate ofevolution. Polarisafion measurements were also employed to study theanodic evolution of oxygen following the addition of oxides, hydroxides,and water t o the melts. It is difficult to account for the experimentalTafel slope (2RT/F) but the formation of the peroxide ion 0 2 2 - is thoughtt o be important.The preparation of pure germanium by the electrolysisof GeO, in mixed fluoride melts a t 900"c has been reported.89 The authorssuggest that the dissociationis followed by the direct discharge of these ions.Chlorides. Double layer capacitance and electrode kinetic measurementsin molten salts and aqueous solution have recently been reviewed.90 Earlierwork,gl largely by the Russian schools, had shown that the minimum capa-GeO, + Ge4+ + 202-8s P. Mergault and R. Jacoud, Comnpt. rend., 1965, 260, 529.86 M. Rey, Compt. rend., 1965, 260, 5528.87 S. Pizzini and L. Agace, Corrosion Sci., 1965, 5, 193.e 8 S. Pizzini and R.Morlotti, Electrochim. A d a , 1965, 10, 1033.89 R. Monnier and P. Tissot, Helv. Chim. Acta, A964, 47, 2203.So A. D. Graves, G. J, Hills, and D. Inman, in Advances in Electrochemistryand Electrochemical Engineering," ed. P. Delahay and C. W. Tobias, Interscience,New York, 1965; A. N. Frumkin, Svensk kern. Tidskr., 1965, 77, 300; E. A. Ukshe,N. G. Bukun, D. I. Leikis, and A. N. Frumkin, Electrochim. Acta, 1964, 9, 431.91 E. A. Ukshe, N. 0. Bukun, and D. I. Leikis, Izvest. Akad. Nauk S.S.S.R., Otdel.khim. Nauk, 1963, 1, 31; Zhur. $2. Khim., 1962, 36, 322INMAN AND WHITE: MOLTEN SALTS 117citances of metal-melt interfaces were very dependent on the melt com-position but largely independent of the metal. Ukshe and Bukun 92 havemeasured the electrical double layer capacitance of a lead electrode in avariety of binary alkali metal a.nd alkaline earth metal chlorides of thetypes MgCl,-MCl (M = Li, Na, K, Rb, Cs) and XC12-YC1 (X = Ca, Ba, Sr;Y = Na or K).The measurements were made with an impedance bridge 93operating at 20 kc./sec. The reference electrode was Pb-PbC1, (2.5 mole yoin the appropriate solvent melt). The double layer capacitance-electrodepotential curves were symmetrical parabolas about the potential of zerocharge, although in some systems, e.g., MgC1,-LiCl, CaC1,-KCl, CaCl,-NaCl,BaC12-KC1, unexplained steps in the cathodic and/or anodic branches wereobserved. The minimum double layer capacitance (Cmin) was plottedagainst the mole fraction of the components. There do not appear to beany systematic trends in these data except in those cases where complexformation is suspected. In these, a deep minimum is observed at the com-position corresponding to the stoicheiometry of the complex.The data foreach system were interpreted in terms of the structure of the melt com-ponents and in terms of electrostriction. The temperature coefficient ofthe minimum double layer capacitance is large for MgCl, (0.2 pF cm.-2deg.-l) compared with LiCl or NaCl (0.11 pF crn.--, deg.-l) and KC1 orCsCl (0.03 pF (3111.12 deg.-1). There appears to be a simple relationshipbetween Cmin and the cation radius for the pure chlorides of both Group IAand Group IIA metals. This is probably related to both the close packingof the ions in the double layer and electrostrictive effects. The influenceof charge might be resolved if data were available for the system CaC1,-BaCl,to compare with KC1-NaC1 (the latter system appears to be free fromcomplications such as complex-formation) in which a steady decrease inCmin from NaCl through KC1 is observed.The structure of the doublelayer is not clearly understood in molten salt systems, and more work mustbe done before a clear picture can emerge. Delimarskii and Kikhno 94report the values for the points of zero charge on the following solid metalelectrodes: Ni, Ag, Cr, M i , Fe, Zr, Ti, Ta, Be, in BaCl,-KCl a t 700"c verswtheir Ag-Ag+ reference electrode. Ukshe et aLg5 have measured the capaci-tive and resistive components of the impedance of Ni, Fe, and Ti electrodesin molten KCI.The results were discussed in terms of oxide film formation.Oscillographic studies 96 of interelectrode capacitance in molten salts forcells with a small phase shift have been made for porous electrodes. Opti-mum conditions and a rapid method for determining the ratio of the surfaceareas of two pairs of electrodes are reported. Graves and Inman 97 havepresented some differential capacitance measurements of the electrical9 2 E. A. Ukshe and N. G. Bukun, Zhur. neorg. Khim., 1964, 9, 1766, 2494; 1965,10, 551; 729; 731; 1008; Elektrokhinziya, 1965, 1, 113.O 3 D. I. Leikis and B. N. Kabanov, Trudy. Inst. $2. Khim. Akad. Nauk S.S.S.R.,1957, Vp. 7, 5.94 Su. K. Delimarskii and V. S. Kikhno, Ukruin. khim. Zhur., 1964,30,1156; 1965,31, 116; 872.95 E.A. Ukshe, S. I. Stepanov, and N. G. Bukun, Izvest. Akad. Nauk S.S.S.R.,Metal, 1965, 1148.96A. V. Goroclyskii and E. V. Panov, Ukruin. khim. Zhur., 1964, 30, 1060.97 A. D. Graves and D. Inman, NaEure, 1965, 208, 481118 GENERAL AND PEYSICAL CHEMISTRYdouble layer a t platinum-halide-melt interfaces. They identify the ano-malously high capacitances of the anodic branch reported earlier by Laitinenand Roe 98 with the formation of a layer containing oxygen on the electrodesurface. The adsorption of platinum ions on to the charged metal surfaceis evidenced by the double-layer capacitance-potential shifts. These changesare explained by assuming Pt2+ to be present as the [PtC1,12- species.Grislain 99 has reviewed and assessed methods for determining thevapour pressure of inorganic compounds over a wide range of temperature.Kuz’menko and N o v i k o ~ ~ ~ ~ have examined equilibria of the formMRbC1, + MC1+ RbCl where M = K or Na, using vapour compositiondata and a treatment developed by the authors.The nature of the mixeddimer is discussed. Changes in the composition of initially equimolarKCl-KBr solid solutions due to differing degrees of vaporisation have beeninvestigated.lol The effect of alkali metal halide diluents on the solubilityof metallic cadmium in CdC1,-alkali metal chloride melts has been ex-amined.lo2 The solubility and decomposition overvoltage for titaniumtetrachloride in molten KC1 have been measured.103 Threadgill 104 hascontinued his studies of the preparation of metallic calcium by the electro-lysis of calcium oxide dissolved in molten calcium chloride.He found aeutectic composition for CaO-CaC1, a t 17 wt. yo CaO. The solubility ofcalcium in the electrolyte is very low -0.02-0.05~0. The sodium-sodiumchloride system has also been investigated.lo5h g e l l 1 0 6 has published a free volume model of transport for both con-ductance and diffusion in molten salts. This treatment has been used lo’to rationalise departures from the Nernst-Einstein equation in a varietyof pure molten salts. They ara correlated by means of “glass transitionbased ” corresponding temperatures suggested by the free volume model.Coupled with molar volume data these correlations are consistent with theview that mutual ionic interactions cause the Nernst-Einstein equation tofail in these liquids.Angell and his collaborators108 have presented pre-liminary data showing the effect of pressure on transport rates in a repre-sentative melt, Ca(N03)2-KN0, (38 : 62 mole yo). The data are analysedin terms of the free volume model. Grantham lo9 has measured the con-ductivity of molten Bi-BiBr, solutions as a function of temperature overthe whole range of compositions. The conductivity of Bi-BiC1, solutionswas also measured in the composition range 0-30 mole yo of metal. Above400 O c these systems resemble the Bi-BiI, system investigated earlier,llO9s H. A. Laitinen and D. Roe, Coll. Czech. Chem. Comm., 1960, 25, 3065.99 B. Grislain, Bull. Xoc.chim. France, 1965, 879.100 A. L. Kuz’menko and G. I. Novikov, Vestnik Leningrad. Univ., 1964, No. 22,101P. Luova and P. Tuominen, Suomen Kem., 1964, 37, B, 207.l o a Yu. N. Rodionov and V. R. Klokman, Radiokhirniya, 1965, 7, 159.108 M. V. Smirnov and V. S. Maximov, Elektrokhimiya, 1965, 1, 727.lo4 W. D. Threadgill, J . Electrochem. Soc., 1964, 111, 1408; 1965, 112, 632.106 E. I. Adaev and A. G. Morachevskii, Zhur. priklad. Khim., 1965, 38, 2105.106C. A. Angell, J . Phys. Chem., 1964, 68, 218; 1917.10’ 0. A. Angell, J . Phys. Chem., 1965, 69, 399.108 C. A. Angell, L. J. Pollard, and W. Straus, J . Chem. Phys., 1965, 43, 2899.1oSL. F. Grantham, J. Chem. Phys., 1965, 43, 1415.IlOL. F. Grantham and 8. J. Yosim, J . Chem. Phys., 1963, 38, 1671.102INMAN AND WHITE: MOLTEN SALTS 119in which the conductivity increases monotonously with metal content.Above 500 O c the three predominating transport mechanisms are believedto be ionic below 10% metal, semiconducting between 20-60% metal,and metallic above 80% metal.Bronsteinlll has described an all-metalcell for e.m.f. measurements in corrosive metal-metal halide systems (forfurther discussion of solutions of metals in molten salts see ref. 4). Laityand Moynihan 112 have carried out transference experiments to determinethe relative mobilities of Lif and Kf ions with reference to the C1- ionover a wide range of composition in the KC1-LiC1 system a t 640"~. Thecombination of these results with conductivity data yield equivalent con-ductivity isotherms for each cation.These decrease monotonously withincreasing K+ ion concentration. The Lif ion mobility decreases rapidlyand crosses that for Kf ion a t 20 mole yo of KCl. It would eventuallyreach 20% of its initial value, in pure KC1. Similar behaviour has beenreported for other systems.113 Chelma et aE.113 have discussed their resultsin terms of complex ion formation. Laity and Moynihan take a less extremeview and make use of the model proposed earlier by Lumsden114 to explainheat of mixing data for alkali metal halides. In this model the effect ofthe highly polarising Li+ ion on the polarisable anion (Cl- ion in this case)in a group such as Li+, C1-, K+ is important. Several Li+ ions can becomeimmobilised on the addition of small quantities of KC1 through inducedpolarisation, and this results in the rapid fall in Li+ ion mobility.Onlya slow rise in K+ ion mobility is observed on addition of LiCl to pure KClowing to the consequent weakening of the K+-Cl- attractive forces. Thisqualitative model also explains the viscosity behaviour of LiCl-KC1 melts.Some of the results of Papaioannou and Harrington 39 discussed previouslymay be understood in the light of this model. Using the " diEusion intoa capillary " technique, Bockris, Richards, and Nanis 115 have obtainedself-diffusion coeficients for the Group I1 metal chlorides over a 200"temperature range a t constant pressure. The data have been used to testseveral models for liquids. A version of the hole model enables heats ofactivation to be predicted.Some structural information was deduced byconsidering the deviations from the Stokes-Einstein and Nernst-Einsteinrelationships. Ichikawa, Shimoji, and Niwa 116 have determined the self-diffusion coefficient of calcium ions in molten calcium chloride and trace-ion dif!fusion coefficients of calcium ions in 99.8 mole yo NaCl + 0.2 mole yoCaC1, and 99.8 mole % KC1 + 0-2 mole yo CaC1, using the " diffusion outof a capillary " technique. The results for the self-diffusion coefficient ofCa2+ ions in CaCl, are lower than those obtained by Bockris et al. ThisWerence may arise from errors inherent in the (different) techniques em-ployed. In a survey of self-diffusion techniques, Angell and Tomlinson117111 H.R. Bronstoin, J . Electrochem. SOC., 1965, 112, 1032.lla R. W. Laity and C. T. Moynihan, J . Phys. Chem., 1964, 68, 3312.113 J. A. A. Ketelaar and E. P. Honig, J . Phys. Chem., 1964, 68, 1596. F. Lantelme114 J. Lumsden, Discuss. Furuduy SOC., 1961, 32, 138.lX5 J. O'M. Bockris, S. R. Richards, and L. Nanis, J. Php. Chern., 1965, 69, 1627.116 K. Ichikawa, M. Shimoji, and K. Niwa, Ber. BunsengeseUschaft phys. Chem.,11' C. A. Angell and J. W. Tomlinson, Trans. Faraday SOC., 1965, 61, 2312.and M. Chemla, Bull. Xoc. chim. France, 1960, 2200.1965, 69, 248120 GENERAL AND PHYSICAL CHEMISTRYsuggested that the " diffusion out of a capillary " technique is the mostreliable. They also suggest that the method of diffusion in a porousrefractory strip should be further exploited.These authors employed theformer method for determining the self-diffusion coefficient in molten leadand thallous chlorides. The results are discussed in the light of varioustheories of transport in ionic liquids. Laity and McIntyre 118 have developeda rigorous treatment which relates the chronopotentiometric diffusion co-efficient, Dch, t o other transport properties in fused salt systems. It isshown that D,, becomes equal to when the concentration is sufficientlysmall (<0.04~). A new method is proposed to take account of the doublelayer charging current in determining the value of z to be used in thecalculation of Dch. Smirnov et have measured the diffusion coefficientof molybdenum ions in several molten alkali metal chlorides and theirmixtures over a range of temperatures by chronopotentiometry.The rateof diffusion of Mo3+ ions decreases as the solvent cation radius increases.The '' jump over " mechanism proposed is similar to that proposed byLaity and Moynihan (see above). Diffusion coefficients l20 of Pb2+, Cd2+,and Zn2+ ions in fused NaC1-KCl have been measured by chronopotentio-metry.High temperature modifications of the Unicam S .P.500,121 the Cary14 H,122, 123 and the Unicam S.P.700 124 spectrometers have been described.A system for preparing pure melts in situ is described.124 The spectrumfor neodymium chloride in the LiC1-KC1 eutectic illustrates the performanceof the S.P.700 spectrometer. The spectra of fourteen lanthanide chloridesin LiC1-NaC1-KC1 in the range 0.8-245 p between 400 and 800"c arereported 122 and compared with similar data in water and molten nitraternedia.47 The effect of the 4f electrons is manifested by the absence ofbands for certain elements.Mamiya l22 has also investigated the absorptionspectra of Ni2+ and Co2+ ions in the LiC1-KC1 eutectic over the temperaturerange 360-7OO"c. Below 390"~ the splitting of the near-i.r. band is in-terpreted in terms of complex species. The spectra of Co2f and Ni2+ ionsare temperature-independent above 500 Oc and ascribed to a single species.Kukk 125 has examined the visible and near-i.r. absorption spectra of &In2+,Co2+, and Ni2+ ions in alkali and alkaline earth halide solvents. Comparisonof these spectra with those obtained in other solvents and in the solid stateindicates that these metal ions are tetrahedrally co-ordinated in LiC1-KCI,LiCl, LiBr-KBr, and CaCl2-MgCl2.E.s.r. spectra are also reported forMn2+ ions in KC1, LiCl, and LiC1-KC1, over the temperature range 25-900"~. N.m.r. studies in molten salts have been reported by Hafnerand Nachtrieb l 2 6 using 205Tl in various pure thallium salts and their118R. W. Laity and J. D. E. McIntyre, J . Amer. Chem. Soc., 1965, 87, 3806.M. V. Smirnov, 0. A. Ryzhik, and G. N. Kazantsev, Elektrokhimiya, 1965,1, 59.120 T. Yanagi, T. Ikeda, and M. Shinagawa, J . Chem. Soc. Japan, 1965, 86, 898.1 2 1 D. N. Henty and D. H. Kerridge, J . Sci. I~zstr., 1965, 10, 756.1z2 M. Mamiya, Bull. Chem. SOC. Japan, 1965, 38,178; Japan Analyst, 1965,14,519.123 C .R. Boston and G. P. Smith, Rev. Sci. Instr., 1965, 36, 206.134 R. A. Bailey and J. A. McIntyre, Rev. Sci. Imtr., 1965, 36, 968.125 M. Kukk, Diss. Abs., 1964, 25, 1602.126 S . Hafner and N. H. Nachtrieb, J . Chem. Phys., 1964, 40, 2891; 1965, 42, 631;Rev. Sci. Instr., 1964, 35, 680INMAN AND WHITE: MOLTEN SALTS 121mixtures with alkali metal halides. The results yield information on cation-anion interactions in molten salts. A detailed spectroscopic study oftransition metal ions in molten AlCl, has been reported.127 The authorsshowed that bivalent Ti, V, Cr, Mn, Fe, Co, Ni, and Cu are octahedrallyco-ordinated in this solvent. This may be compared with the tetrahedralco-ordination exhibited by all except V2f in alkali metal chloride media.l**They1,' have also examined the effect of varying the KCl concentrationin the solvent KC1-AlC1, on the spectrum of Co2+.Below 42 mole % ofKCl, the spectrum is interpreted in terms of Co(A&Cl,), species with theCo2f ion in an octahedral co-ordination. A mixed complex Co(A12C17)(AlC14)is in equilibrium with C0(A12C17), and [AlCl,]- in the region 42-49 mole yoof KCl. The equilibrium constant a t 300"c was found to be 3.5 x ~ O - , M .The octahedral co-ordination of the CoZf ion in the mixed complex isseverely distorted. Viscosity data 129 and Raman spectra 13* obtained forthe KC1-AlCl, (51 : 49 mole %) and NaCl-AlC1, (51 : 49 mole yo) confirmthe presence of [A1C14]- species a t these compositions. X-Ray data 131 forthe compounds formed from the bivalent metal chloride-aluminium chloridefused salt systems have been tabulated.Ibers 132 reports the formation ofa compound CoC1,,2A1C13 from the molten mixture of CoC1, and AlCl,.Spectra for Tlf, Pb2+, and Bi3f ions in LiC1-KC1 have been r e ~ 0 r t e d . l ~ ~Greenberg and Warshawsky 134 have continued their study of alkali metalsdissolved in fused salts. The state of the metal in solution depends onthe concentration (see also ref. 109). In dilute solution (less than l W 3mole yo), F-centres are formed. As the concentration increases, atomic andmolecular species form. At high metal concentrations and above the con-solute temperature, the metal exists in the metallic state. Charge transferand ligand field spectra of (tetrahedral) tetrahalogenonickel( 11) ions inmolten dimethyl sulphone and molten organic halide salts have beenre~0rded.l~~ It is suggested that molten dimethyl sulphone is a particularlyuseful solvent for the study of transition metal complexes.The clearestexamples of complex formation in molten salts are found when the organicquaternary ammonium salts are used as solvent. The Raman spectra 136of BaC12--NaN03 and BaCl,-AgNO, melts have been examined at 430"c.The Raman lines obtained indicate complete dissociation, in agreement withcryoscopic data. On the other hand, BaC1,-KC1 melts give lines whichmay correspond to the species [BaCl,]-. No such definite indication wasreported by Ukshe and Bukun (see above) although there is some indica-tion of a minimum in the minimum double layer capacitance versus mole yoplot for this system.Hamer, Malmberg, and Rubin 137 have completedIz7 H. A. 0ye and D. M. Gruen, Inorg. Chem., 1964, 3, 836; 1965, 4, 1173.12* D. M. Gruen and R. L. Mcbeth, Pure Appl. Chem., 1963, 6, 23.12s I. A. Kryagova, Zhur. fiz. Khim., 1939, 9, 1759.13* K. Balasubrahmanyan and L. Nanis, J . Chem. Phys., 1965, 42, 676.131 R. F. Belt and H. Scott, Inorg. Chem., 1964, 3, 1785.132 J. A. Ibers, Acta Cryst., 1962, 15, 967.133 G. P. Smith, D. W. James, and C. R. Boston, J . Chem. Plzys., 1965, 42, 2249.13* J. Greenberg and I. Warshawsky, J . Amer. Chem. Soc., 1964, 86, 3572; 5351.135 G. P. Smith, C. H. Liu, and T. R. Griffiths, J . Amer. Chem. SOC., 1964, 86, 4796.136 J.Valiier and R. Lira, Compt. rend., 1964, 259, 4579.13' W. J. Hamer, M. S. Malmberg, and B. Rubin, J . Electrochem. Soc., 1965, 112.7 50.122 GENERAL AND PHYSICAL CHEMISTRYtheir calculations of e.m.f.s from thermodynamic data for cells containingsingle solid or liquid fluorides, chlorides,138 bromides, and iodides for thetemperature range 25-1500"~. Hamer 139 has also published data forsingle metal oxide systems over the temperature range 25-3000"~. Thisseries is not as complete as that for the halides because of the thermalinstability of many of the metal oxides. Sethi and Gaur 140 have publishedsimilar data for formation cells containing oxides of lead and bismuth aselectrolytes. Their results agree fairly well with available experimentaldata.Leonardi and Brenet 141 describe a new design of chlorine referenceelectrode. Their E" for the cell Ag i AgCl 1 C1, is in reasonable agreementwith that of Hamer et ~ 1 . l ~ ~ Kisza 142 has established an e.m.f. series basedon the hydrogen electrode in molten dimethylamine hydrogen chloride inthe temperature range 170-200"c for some metal chlorides. The couplesstudied were Cu2+-Cu+, Cu2+-Cu, Ag+-Ag, Bi3+-Bi, Ni2+-Ni, Cuf-Cu,Co2+-Co, Pb2+-Pb, Sn2+-Sn. Activity coefficients calculated for thesesystems indicate strong metal-solvent interactions. Baboian, Hill, andBailey143 report E" values for Ti"-Ti and Ti3+-Ti2+ versus the Pt-Pt2+reference electrode in the LiC1-KCl eutectic at 450" and 550"c. Baboian 14phas also studied zirconium and hafnium ions in this eutectic by potent.io-metry and polarography.The equilibrium potentials of zirconium ions inmolten czsium chloride have also been rep0rted.1~~ Munday146 has in-vestigated the lower oxidation sta,tes of Cd, Pb, Sn, and Zn in moltensodium tetrachloroaluminate. He showed that Cd22f, Pbf, Pb23+, Pbg5+,etc., and Sn,+, Sn,3+, Sndf, etc., are the reduced species present. In thezinc system the electrode potentials were unstable. Okada, Yoshida, andHisamatsu 147 have shown that Cd,2f is the predominant species in solutionsof cadmium metal in molten cadmium chloride and LiC1-KC1 containing30 mole yo CdCl,. Measurements of the e.m.f.s of a series of concentrationcells in the system SnC1,-T1C1 indicate the presence of [SnClJ- and [SnC1J3-species.l48 The SnC12-KC1 system has also been ~tudied.l4~ In the systemTaCl,-MCI, where M = Nay K, Rb, Cs, thermographic analysis 150 suggeststhe presence of [TaCl5I2-.Saeki and Sakulei151 have studied the equi-librium between niobium and niobium subchloride in the LiC1-KC1 eutecticby an e.m.f. method. The presence of NbCl, andNb ,Cl, is suggested. Therefractive indices of NaC1, KCl, CdCl,, PbCl,, and their binary mixtures103, 8.138 W. J. Hamer, M. S. Malmberg, and B. Rubin, J. Electrochem. SOC., 1956,139 W. J. Hamer, J. Electroanalyt. Chern., 1965, 10, 140.140 R. S. Sethi and H. C. Gaur, Indian J . Chem., 1965, 3, 177.1 4 1 J. Leonardi and J. Brenet, Compt. rend., 1965, 261, 113.142 A. Kisza, Bull. Acad. polon. Sci., 1965, 13, 409; 415.143R.Baboian, D. L. Hill, and R. A. Bailey, Canad. J . Chem., 1965, 43, 197.144 R. Baboian, Diss. Abs., 1965, 26, 6426.145 V. Ya. Kudyakov and M. V. Smirnov, Elektrokhimiya, 1965, 1, 143.146 T. C. F. Munday, Diss. A h . . 1965, 25, 6216.14' M. Okada, H. Yoshida, and Y. Hisamatsu, J. Electrochem. SOC. Japan, 1964,148 J. Josiak and J. Terplowski, Roczraiki Chem., 1965, 39, 805.Peng Hsui-Wu and Wan Sew-chew, Sci. Sinica, 1965, 14, 1379.1 5 O V. V. Safonov, B. G. Korshunov, Z. N. Shevtsova, and S. T. Bakum, Z h w .151 Y. Saeki and T. Sakulei, J. Less-Conamon Metals, 1965, 9, 362.32, 99.neorg. Khim., 1964, 9, 1687INMAN AND WHITE: MOLTEN SALTS 123have been measured over a range of temperature^.^^^ Deviations fromadditivity for the CdCl,-KCl and PbC1,-KCl systems provide further evi-dence for complex-formation in these melts.Bayanov and Serebrennikov 15shave investigated the properties of ceriuni and erbium dissolved in Zn, Pb,Cd, and Bi by the e.m.f. method using the LiC1-KCl eutectic as the moltenelectrolyte. This method has also been employed t o examine the reductionof molten cerium trichloride by liquid cerium.154 Roms and Delimarskii 155have studied the thermodynamics of dilute solutions of AgCl dissolved inPbCl,-KCl-NaCl eutectic by the e,m.f. method. The excess functionscalculated for AgCl indicate the presence of complex species. The inter-pretation of excess functions in this way is always, of necessity, ambiguous.The electrodeposition of nickel from the molten NaC1-PbCl eutectic con-taining Ni2+ ions has also been investigated.lS6Work using dropping-metal electrodes has been reviewed.157 Delimarskiiand Kuz’movich 158 report the successful use of a dropping-bismuth electrodein NaC1-KC1 a t 700”~.The apparatus described enabled the drop timeand drop size to be varied within wide limits. The Heyrovsliii-Ilkovicequation described the Cd2+ ion reduction wave, but it was necessary toemploy the Kolthoff-Lingane equation for Pb2+ and TI+ ions although thisonly applied to a first approximation. The limiting current (in spite oflarge oscillations) was shown to be proportional to concentration. Diffusioncoefficients were calculated but the values appear to be high. This maybe due to the extreme mobility of the bismuth drop which leads to largemaxima.Panchenko has discussed some limitations of dropping moltenmetal electrodes and the use of va.rions other electrode materials.159 Heproposes the use of an automatic dropping-bismuth electrode. The flowof bismuth is controlled by a valve which is operated by a time relay anda magnetic chopper. He has shown that the limiting current is proportionalto concentration for Ag+ ions in molten LiC1-KC1 at 420”~. The Kolthoff-Lingane equation describes the observed reduction wave. A value of4.9 x loA5 cm.2 sec.-l for the diffusion coefficient is reported to comparewell with the early data of Lorenz l 6 * for this system. However, thisvalue is about twice that reported in more recent work.l61,162 Schmidtet ~ ~ 1 .1 ~ 3 have obtained polarograms for Pt2f, P d z f , Bi3+, and Sb3+ ionsdissolved in LiCl-KCl eutectic a t 450 O c with an intermittently polarisedplat’inum indicator electrode. The waves for Pd2+ ions a t palladium-H. Bloom and B. M. Peryer, Austral. J . CJzem., 1965, 18, 777.153 A. P. Bayanov and V. V. Serebrennikov, Zhur. $2. Khim., 1965, 39, 717.ls4 M. V. Smirnov and V. S. Lvov, Elektrokhirniya, 1965, 1, 833.156 Yu. G. Roms and Yu. K. Delimarskii, Ukrain. khim. Zhur., 1964, 30, 1151,156 S. Ziolkiewicz and G. Morand, J . Chim. phys., 1965, 62, 312.157 See ref. 4a, 681; ref. 4b, 255.15* Yu. K. Delimarskii and V. V. Kuz’rnovich, J . Appl. Chem. (U.X.S.R.), 1964,15* I. D. Panchenko, Zhur. $2. Khim., 1965, 39, 514; I. D. Panchenko and K. M.I6O R.Lorenz, “ Raumerfullung w. Jonen beweglichkeit,” 1922, Leipzig.161 H. A. Laitinen and W. S . Ferguson, Analyt. Chem., 1957, 28, 4.182 C. E. Thalmeyer, S. Bruckenstein, and D. M. Gruen, J . Inorg. Nuclear Chem.,163 E. Schmidt, H, Pfander, and H. Xiegenthaler, Electrochim. Acta, 1965, 10, 429.3, 1484.Boiko, Ukrain. khim. Zhzlr., 1965, 31, 190.1964, 26, 347124 GENERAL AND PHYSICAL CHEMISTRYcovered platinum electrodes and Pt2f ions at pure platinum surfaces weredescribed by the Kolthoff-Lingane equation. Bismuth and antimony formalloys with the platinum substrate. Diffusion coefficients for these metalions were calculated. Tanaka et aL16* have summarised recent advancesin polarography in Japan, including molten-salt work. The electrodepositionof bismuth from BiCl,, Bi203, and BiOCl dissolved in chloride and boraxmelts has been r e ~ 0 r t e d .l ~ ~ The cathodic deposition from KC1-LiC1-BiCl,melts at low concentrations of BiC1, at temperatures between 400 and 600"cis diffusion-controlled. At higher concentrations the mass-transfer polarisa-tion is negligible. The limiting current densities observed at molybdenumelectrodes for Bi,O, dissolved in CaCl,-NaCl between 600 and 9OO"c in-crease with temperature. The cathodic deposition of Bi3+ ions from BiOCl-BaC1,-CaCl,-NaCl at 900 Oc is also mass-transfer polarised. Anodic chlorineevolution 166 on graphite electrodes has been investigated in A1C13-NaC1 a t19O"c and PbC1,-NaC1 at 430"~. Tafel equation coefficients and electricaldouble layer capacitances have been obtained from decay and chargingcurves at both temperatures. Roughness factors are calculated and usedt o correct the exchange current densities calculated from the analysis ofthe charging curves.The overall electrode process was found to be reaction-polarised at the lower temperature and charge-transfer polarised at 430 "c.Fondanaiche and Kilundai 167 have shown that chlorine evolution on graphitein molten NaCl (820-9OO"c) and NaC1-KC1 (700-900 "c) occurs withoutappreciable polarisation. The thermodynamics of the hydrogen electrodeand the rate and mechanism of hydrogen deposition in solutions of hydrogenchloride in fused chlorides have been studied.lasb Mass-transfer polarisationcontributes to the overall polarisation observed. The proton may be presentin the melt as the [HCl,]- ion (see ref.88).The variation of surface tension lag with composition andtemperature in the system Cd2+, K+, C1-, Br- has been used to investigatethe presence of complex species in the melt. The results indicate thepresence of [CdX,]-, [CdX,]2-, and mixed halogen complexes. Stern 17Ohas continued investigations of electrode potentials in fused salts with astudy of the liquid junction potentials in the AgC1-AgBr system. Theassumption that liquid- junction potentials are negligible in molten salts isonly strictly valid in dilute solutions where the solvent ions carry the bulkof the current through the melt. A parallel assumption that transportnumbers in molten salts are -0.5 has been shown to be unreali~tic.l7~, 172Anion transport numbers are largely uninvestigated. Although liquid-junction potentials in binary melts containing two cations have been ex-164 N.Titnaka, E. Itabashi, and T. Ito, J. Electrochem. SOC. Japan, 1964, 32, 119.1135 F. Colom and L. Alonso, Electrochim. Acta, 1965, 10, 835.166 H. J. Vandenbroele, Rev. Fac. Cienc. quim., Univ. m c . La Plata, 1962/3, 34,16' J. C. Fondanaiche and T. Kikindai, Cornpt. rend., 1965, 260, 2801.16* (a) H. A. Laitinen and J. A. Plambeck, J. Amer. Chem. SOC., 1965, 87, 2202;lG9 R. B. Ellis and A. C. Freeman, J. Phys. Chem., 1965, 69, 1443.1'1 E. P. Honig, Ph.D. Thesis, Amsterdam, 1964.1~ A. Berlin, F. Mkncs, S. Forcheri, and C. Monfrini, J. Phys. C'hem., 1963, 67,Bromides.215.(ZI) E. A.Ukshe and V. N. Devyatkin, EEektrokhinaiya, 1965, 1, 627.K. Stern, J. Electrochem. Soc., 1965, 112, 1049.2505INMAN AND WHITE: MOLTEN SALTS 125tensively investigated, similar systems containing two anions have receivedlittle attention.The system becomes less ideal with increasing AgCl concentration. tBr-decreases and eventually becomes negative as the mole fraction of AgBrin the mixture is reduced. It was thus necessary to take account of complexspecies such as Ag,Rr+. Van Norman173 has measured the solubility ofsilver in molten silver chloride and silver bromide at 520"c, using in situchronopotentiometry. The solubility of silver in AgCl is 0.0123 mole yoand in AgBr 0.0118 mole yo. The diffusion coefficient of the soluble specieswere found to be 2.0 x cm.2 sec.-1 in AgCl at 620°c, and 4.2 xcm.2 sec.- 1 in AgBr at 500"~. Analysis of the anodic chronopotentiogramsindicated that the oxidation was a reversible one-electron process.Markvvand Podafa174 have measured the redos potential of the couple Ti2+-'l'i3+in molten KBr-NaBr at 700"~.Karl and Klemm 175 have determined the electrical conduc-tivities of lithium iodide, rubidium bromide, and lead(@ iodide over a widerange of temperatures. Sternberg et a,Z.176 have established a reversibleI,-I- electrode in molten AgI.MiScellaneous.--Thiocyunutes. The ionic nature of some alkali metalthiocyanates has been deduced by Raman spectroscopy 1 7 7 a t temperaturesabout 20"c above the melting point.The SCN- group is a discrete kineticentity in the melts. The symmetric stretching frequencies v1 are comparedwith those obtained for aqueous solutions of the thiocyanates. The v1frequencies are found to depend on the cation field strength, as the nearestneighbours of anions in melts are on average cations. In aqueous solutionthe frequency v1 does not vary with the cation. This may be attributedto the shielding effect of hydration.Polarographic, chronopotentiometric, and conductometric studies ofthiocyanates have been employed t o evaluate these melts for high-tempera-ture batteries.178 Their electrochemical decomposition is limited on theanodic side by the reactionsStern employed the cellAg I &GI( Xi) ,AgBr( X,)iiAgCl( Xi1) A@r( XZ1) 1 Ag.Iodides.BCNS- -+ (CNS), + 28at +0*25v versus their Ag-Ag+ reference electrode, and on the cathodicside by the reactionCNS-+2e --+ CX- + Ss-at -1-75 V.Alkali metal deposition occurs at more negative potentials.(The reaction K+ + e + K occurs at - 2 . 9 3 ~ and the reactionNa* + e --+ Na at -2-35 v.) The conductance plot log K versw 1/T w-asshown to be essentially linear. The addition of AgBr, NaI, NaBr, NaC1,KC1, LiCl, and LiSCN did not markedly affect the conductance of the melt.x(CNS), + (CNS)*Z173 J. D. Van Norman, J . Electrochem. Soc., 1965, 112, 1126.17* B. F. Markov and B. P. Podafa, Ukruirz. khim. Zhur., 1965, 31, 873.175 W. Karl and A. Klemm, 2. Naturforsch., 1964, Ma, 1619.176 S. Sternberg, I. Adorian, and I. Galasiu, J .Chim. phys., 1965, 62, 63.177 C. B. Baddiel and G. J. Janz, Trans. Furuday SOC., 1964, 60, 2009.17* R. E. Panzer and 31. J. Schaer, J. Electrochem. SOC., 1965, 112, 1136126 GENERAL AND PHYSICAL CHEMISTRYA series of factorially designed tests were carried out t o investigatesuch variables as anode and cathode materials, electrolyte, atmosphere,resistive load, temperature, and electrolyte matrix in order to designoptimum working conditions for the voltaic cell. At 200"c and withcurrent densities of 100 m~ cm.-2, closed-circuit voltages ranged from 1-5to 2.5 for at least 5 minutes. This performance is nearly equivalent tothat of the best previous thermal cells in LiCI-KC1 operating a t 450"c.The conductivities and viscosities of inorganic melts and organic quaternaqammonium salt melts have been compared.179 In the quaternary ammoniummelts E,/EA is approximately unity, whereas in inorganic salt melts theratio is closer to five.In the former systems, EA and Ev seem to be almostindependent of the cation a t a given temperature. The results for theorganic melts can be readily explained in terms of steric effects; densitymeasurements, and studies with models of tetraisopentylammonium thio-cyanate were employed. The results for inorganic melts such as nitrateshave been explained in terms of ion association.ls0 The SCN- ion can fitinto the small interstices formed between the close-packed quaternaryammonium ions. Thus, the free rotation of the cation and movement ofthe SCN- ions from one interstice to another is hindered.The large experi-mental values for the activation energy of conductance (-8-5-1 1 kcal.mole-1 ; cf. 2 kcal. mole-1 for inorganic melts) support this view. Moltenpotas-sium thiocyanate can act as a reducing agent for transition-metal oxyanions.lslSuZphutes. The electrical conductance l S 2 of lithium sulphate has beenmeasured over the temperature range 575-970"~. It was found that anempirical equation of the form K = a + bt + ct2 (t = "c) fits the data,better than an Arrhenius type of equation. The ratio between the equi-valent conductance and the self-diffusion coefficient is less than that requiredby the Nernst-Einstein equation. The results are analysed in terms of thefrictional coefficient formalism la3 using earlier self-diffusion data.18* Thenegative value of r++ indicates some ion-association in the melt.ls5 Ramanspectra 166 in alkali metal sulphate melts also provide evidence for strongcation-sulphate interactions.The plot of Av(v,,) versus Zi/q (for thecations) is linear. The spectra for Cr3+ and Cu2f ions in molten sulphateshave now been analysed in terms of ligand-field theory.187 The resultsshow that the Cr3+ ion is octahedrally co-ordinated in sulphate melts (withA = 14.3 kK, t9 = 0.72). It is suggested that three bidentate sulphate ionsprovide the six oxygen atoms at the corners of the octahedron. The octa-hedral co-ordination of the Cu2+ ion on the other hand is severely distortedand involves two bidentate sulphates in the xy-plane and possibly twounidentate groups a t a greater distance from the metal ion along the z-axis.17O G.J. Janz, R. ID. Reeves, and A. T. Ward, Nature, 1964, 204, 1188.l80 E. Rhodes, W. E. Smith, and A. R. Ubbelohde, Proc. Roy. SOC., 1965, A, 285,181D. I€. Kerridge and M. Mosley, Chenz. Comm., 1965, 505.laa A. LundBn, 2. Naturforsch., 1965, 20a, 235.18a R. W. Laity, J . Chem. Phys., 1959, 30, 682; Discuss. FaTaday Soc., 1961, 32, 172.184 A. LundBn, 2. Naturforsch., 1962, Ira, 142.186 R. W. Laity, Ann. New York Acad. Sci., 1960, 79, 997.186 G. E. Walrafen, J . Chem. Phys., 1965, 43, 479.1 8 7 K. E. Johnson, R. Palmer, and T. S . Piper, Spectrochim. Acta, 1965, 21, 1697.263INMAN AND WHITE: MOLTEN SALTS 127Miller and Seward 188 have investigated galvanic cells in molten bisulphatesolvents (mainly ammonium bisulphate).The solubilities of HgI, HgII, andAgI sulphates were found to be 0*00065, 0.0085, and 0.0215 moles per moleof ammonium bisulphate respectively a t 160"c. The cellsPt I Hg,S0,(sst.),HgS0,(Cl),NH4HS04 ii ref. (A)have been investigated using the reference electrode Pt I Hg,SO,(sat.),HgSO,(sat.), NH,HSO, ii . The e.m.f. of cell A was found to be adequatelyrepresented by the expressionand Ag I Ag,S0,,NR4HS0,,ii ref. (B)E = Eo + Eref. - (0.0861/2) log (CH~SO,~K~S~/CSO,,-~~S)a t high sulphate concentrations. The silver electrode was found to behaveideally with respect to the Ag+ ion concentration in cell B. The e.m.f. ofthe cell varied linearly with the acidity or basicity of the system.How-ever, it decreased anomalously as the SOk2- ion concentration was increased.The viscosity of ammonium bisulphate with various additions of ammoniumsulphate was measured over the temperature range 160-180"~. No struc-tural changes to account for the anomalous behaviour mentioned abovewere found. The kinetics of hydrogen evolution on bright and blackplatinum electrodes during the electrolysis of molten potassium hydrogensulphate have been studied.189 The results have been discussed in relationto the earlier work of Shams El Din in ref. 90. Laitinen190 has reviewedthe high-temperature polarography of oxyanions (including Sod2-). Thereactions are complicated, and poorly understood in many cases, and muchwork remains to be done.The anodic discharge of the SOg2- ion a t acarbon electrode in molten Na,SO, a t 700"c has been studied by producta,nalysis, and the results compared with thermodynamic predictions.lgl Themost likely reaction was found to beSO,2- - 2e + C + SO, + CO,Carbonates. The electrical conductivities, densities, and surface tensionsof some binary and ternary alkali metal carbonate systems have beenreported.lg2 Tracer-diffusion coefficients lg3 have been measured for Naf,K+, and C032- ions in the Li,CO3-Na,CO3-K2CO3 eutectic using the" diffusion out of a capillary " technique. Errors caused by end-effects inthis technique are extensively discussed. The diffusion coefficient of theC032- ion in sodium carbonate is approximately one half that of the Na+ion, whereas in the ternary eutectic the difksion coefficient is some 6-10times smaller than those of Naf or K+ ions.The molar conductance of188 J. P. Miller and R. P. Seward, J . Phys. Chem., 1965, 69, 3156; J. P. Miller,lS9 A. J. Arvia, A. J. Calandra, and H. A. Videla, E1ectrochi.m. Acta, 1965, 10, 33;lgo H. A. Laitinen, Talanta, 1965, 12, 1237.lD1 I. T. Guldin and A. V. Buzhinshya, Elektrokhirniya, 1965, 1, 716.lS2 A. T. Ward and G. J. Janz, Electrochim. Acta, 1965, 10, 849.lD3 P. L. Spedding and R. Mills, J . Electrochem. SOC., 1965, 112, 594.Diss. Abs., 1965, 25, 4428.H. A. Videla and A. J. Arvia, ibid., 1965, 10, 21128 GENERAL AND PHYSICAL CHEMISTRYsodium carbonate calculated from the tracer diffusion coefficients is coni-pared with the experimental data of Janz and Lorenz.194 The calculatedvalues exceed the measured values above 9OO"c.These deviations fromthe Nernst-Einstein equation may be explained in terms of a Grotthus-type mechanism involving rotation of ion-pairs such as Mf C032- assuggested earlier.194 Rolin and Recapet l g 5 have continued their study of thethermodynamic properties of alkali metal carbonates. They report enthalpyand heat of fusion data for Li2COB, Na2C03, and K2C03, and their eutecticmixtures. They have also investigated the dissociation of NaC1, NaOH,and Na20 in molten Na2C03 cryoscopically. Ingram and Janz 196 havepresented a thermodynamic analysis of corrosion in molten carbonatessimilar to that of Pourbaix 197 in aqueous solutions.This had previouslybeen extended to molten salt systems by Littlewood.198 The predictionsof this analysis require experimental verification. An electrochemical seriesin molten carbonates is formulated for several metals, and acid-base pro-perties in these systems discussed.196 Outhier 199 has discussed the propertieswhich metallic oxides should possess if they are to be used as porous oxygenelectrodes in molten carbonates. Busson et uZ.200 have investigated theinteraction of the acid-ba,se systems based on the carbonate ion and waterin molten alkali metal carbonates. K = for the reactionCO, + 20H- + H20 f -k GO,,-They have also carried out a thermodynamic analysis of the oxygen electrodein the Li2C03-Na2C03-K2C0, melt. Delimarskii et uE.201 have studied thereactions occurring during the electrolysis of fused carbonates. Carbon isa reduction product a t the cathode. A limiting current for oxide ionoxidation was observed a t the anode prior to the direct discharge of thecarbonate ions. The cathode reaction 202in fuel cells employing carbonate electrolytes has been investigated onplatinum and palladium electrodes.Shvedov and Ivanov 203 have measured the transportnumbers of Na+ and K+ ions in their respective molten hydroxides overa temperature range 380-5OO"c using an all-nickel cell assembly and aHydroxides.lg4 G. J. Janz and M. R. Lorenz, J . Electrochem. Soc., 1961, 108, 1052; J . Chenz.195 M. Rolin and J-M. Recapet, BulZ. SOC. chim. France, 1964, 2504, 2511.lQ6 M. D. Ingram and G. J. Janz, Electrochim. Acta, 1965, 10, 783.197 M. Pourbaix, " Thermodynamics of Dilute Aqueous Solutions," Arnold, London,198 For example, R. Littlewood, J . Electrochem. Soc., 1962,109,525; Trans. A.I.M.E.,lSQ G. Outhier, Compt. Tend., 1964, 259, 3249; 1965, 261, 986.2oo N. Busson, S. Palous, R. Buvet, and J. Millet, Compt. rend., 1965, 260, 6097;2O1 Yu. K. Delimarskii, V. F. Grishchenko, and A. V. Gorodyskii, Ukrain. khim.2O2 A. V. Silakov, G. S. Tyurikov, and N. P. Vasilistov, Elektrokhimiya, 1965, 1,2O3V. P. Shvedov and I. A. Ivanov, Zhur. Jiz. Khim., 1965, 39, 756.and Eng. Data, 1961, 6, 321.1949.1965, 233, 772.1965, 261, 720.Zhur., 1965, 31, 32.613INMAN AND WHITE: MOLTEN SALTS 129porous corundum diaphragm. The transport number found for the Naf ionwas 0.1 & 0-03 and for the K+ ion 0.03 -& 0-03. Afanas'ev and Gamazov 204have investigated the platinum electrode in molten sodium hydroxide meltsat 500"c. The electrode potential depends on both the melt composition,e.g., the oxide and hydroxide ion concentrations and the gas phase compositionabove the melt. The E versus log a0-2, and log aOH-, plots were straightlines whose slopes were almost the theoretical values. Delimarskii and hisco-workers 205 have reported investigations on some intermetallic compoundsin alkaline melts. Delimarskii and Zarubitskii 206 have also studied the im-pedance of nickel electrodes in fused NaOH at 340"c. The capacitanceof the nickel electrodes rises markedly on passivation. The changes ofthe impedance components with cathodic polarisation were studied anddiscussed.The solubility of TiO, in a variety of molten salts(mainly borates and fluorides) has been in~estigafed.~~' Delimarskii andNazarenko 208 have measured the solubilities of metal oxides in fused borax.Kamyshov et aZ.209 have studied the effect of electric current on the rateof nitrogen dissolution in molten oxides. Kimura and Hayakawa 210 haveinvestigated some metal oxides in molten borax using a voltammetrictechnique with a micro-platinum cathode. Both E, values and the limitingcurrents are shown to be independent of concentration. This latter, perhapssurprising observation, is discussed in terms of variations in the gross meltstructure. The limiting current is stroiigly dependent upon temperaturediL/dt - 2-60/, deg.-l compared with 1% deg.-l in other fused salt systems).Colom and Alonso have also carried out a voltammetric study of Bi20,in molten borax using both molybdenum and platinum micro-electrodes.With the platinum electrode, polarograms could only be obtained between800 and 900"~ and when the mole fraction of Bi,O, was less than 0.01.Mitchel1211 has studied the structure of boric oxide melts containing F-ions by vibrational spectroscopy. The melts are diluted with KBr andquenched prior to measurement. The results show close agreement withexisting frequency and structural data 212 obtained on the quenched un-diluted melts. No evidence was found for the incorporation of the F- ionin the boron-oxygen network. The effect of F- and 02- ions on the moltenboric oxide are further examined213 using as probe the electronic spec-trum of C02+. At high F-Polymeric systems.The results confirm the earlier conclusions.204A. S. Afanas'ev and V. I?. Gamazov, Zhur. $z. Khim., 1964, 38, 2823.205 Yu. K. Delimarskii, 0. G. Zarubitskii, and I. G. Pavlenko, Ukrain. khim. Zhur.,1964, 30, 1289; 1965, 31, 573; Yu. K. Delimarskii and 0. G. Zarubitskii, DopovidiAkad. Nauk Ukrain. R.S.R., 1965, 619.206 Yu. K. Delimarskii and 0. G. Zarubitskii, Dopovidi Akad. Nauk Ukrain. R.S.R.,a07 I. N. Anikin, I. I. Naumova, and G. V. Rumyantseva, Kristallograjya, 1965,20* Yu. K. Delimarskii and G. D. Xazarenko, 'Cikrain. khint. Zhur., 1965, 31, 813.200 V. M. Kamyshov, 0. A. Esin, S. K. Chuchmarev, and A. A. Dobryden, Elektro-210 Y . Kimura and Y . Hayakawa, J . Electrochem. SOC. Japan, 1964, 32, 37.211 A. Mitchell, Trans. Faraday SOC., 1965, 61, 5,212 I. C. Hisatsune and N. H. Suarez, Inorg. Chem, 1964, 3, 168.213 A. Mitchell, Trans. Faraday SOC., 1965, 61, 2295.1965, 485.10, 230.khimiya, 1965, 1, 227130 GENERAL AND PHYSICAL CHEMISTRYconcentrations, however, the reaction1\O F I4- BOF B + B B B B \ 1 \ / \ / \ /0' '0' \ / \ 0 0 0 0 0 0-Ioccurs.have studied the reactions between metal oxidesand molten sodium metaphosphate up to 900"~. The products werenot simple pyro- or ortho-phosphates but polyphosphates of the typeMnNa15-,P,025, where M = Ti, Fe, Co, Cu, Pb, Bi. Kingsley et aZ.215 havemade a spectroscopic study of the Mn043- ion in calcium halogenophos-phates. Riebling and Gabelnick 216 report measurements of electrical con-ductivity in alkali metal germanate melts at 1300"~ using the cell whosedesign was reported earlier.217 The results are discussed in terms of cationvolumes and cation-oxide ion interactions. Some of their results are ex-plained in terms of the GeO, octahedra which may be present. The resultsare also compared with those for other glass-like melts and molten salts.Viscosity and density measurements 218 of sodium aluminogermanate meltshave provided structural information.214 Yu. K. Delimarskii, V. N. Andreeva, and T. N. Kaptsova, Izvest. Akad. NaukS.S.S.R., Neorg. Materialy, 1965, 1, 150.216 J. D. Kingsley, J. S. Prener, and B. Segall, Phys. Rev., 1965, 137, 189.216 E. F. Riebling and S. D. Gabelnick, J . Electrochem. Soc., 1965, 112, 822.217 E. F. Riebling and P. C. Logel, Rev. Sci. Instr., 1965, 36, 425.218 E. F. Riebling, J . Chem Phys., 1965, 43, 1772.Delimarskii e

ISSN:0365-6217    

DOI:10.1039/AR9656200007

出版商:RSC    

年代:1965

数据来源: RSC

摘要:

1. INTRODUCTIONBy J. Lewis and N. L. Paddock(The Department of Chemistry, The Victoria University of Munchester)THE general pattern of the Report follows the layout used by the previousReporters. The section on complexes is restricted to carbonyl compoundsand organometallic compounds of the transition elements ; the chemistry ofthe organic derivatives of the typical elements is discussed in the Report onOrganic Chemistry.There have been no major developments in inorganic chemistry duringthe past year-perhaps the most interesting work has been the preparationof adducts of transition metals with carboranes, analogues to mcyclopenta-dienyl metal derivatives. The proceedings of the Eighth InternationalConference on Co-ordination Chemistry have been published as a book1 andthe plenary lectures of the Conference have been reported.2 The Pro-ceedings of the Chemical Society have been replaced by Chemical Communica-tions, which appears bi-monthly.The number of publications continues to rise sharply and the availablespace has allowed mention of rather less than half of those which would havebeen included on the basis of chemical interest.The Reports are thereforeillustrative rather than comprehensive. In references to Russian Journalsthe page number of the English translation has been given.ed. V. Qutmann, Springer-Verlag, Vienna/New York, 1964.“ Proceedings of the 8th International Conference on Co-ordination Chemistry,”Pure Appl. Chern., 1965,10, 1-702. THE TYPICAL ELEMENTSBy B. F. 0. Johnson, N.L. Paddock, and M. J. Ware(Department of Chemistry, The Victoria University of Manchester)MOST of the papers published in the year under review are concerned withthe chemistry of a single element, and are classified below accordingly.A few deal with donor-acceptor reactions of a range of compounds, usuallymetallic halides, in polar non-aqueous solvents, the extent of interactionbeing measured thermochemically (phosphorous oxychloride,lU dimethyl-formamide l b ) , conductometrically lC (acetic anhydride), and by infrared Id(acetone) and nuclear magnetic resonance le spectroscopy (dimethylforma-mide). The chemical reactions occurring in fused salts have been discussed ;zaand a general account has been given 2b of the co-ordination model for non-aqueous solvents [with special reference to POCl, and PO(OEt),].Thereactions of metal halides with ammonia and aliphatic amines 3a and withalkyl cyanides 3b have been reviewed. Eight-co-ordination has been achievedfor In, Sb, Pb, and Sb in complexes with tropolone and aminotroponimine,*a,nd recent work on cationic complexes has been reviewed.5 A detailedaccount has been published of the strengths of bonds from metals to carbon,6and the bonding of the species found in vapours of the elements has beendiscussed.7 A review on fluorocarbon derivatives of the metals 8 and aseries of papers on the industrial synthesis and application of organometallicshave been p~blished,~ the latter (248 pp.) having a much wider scope thanits title indicates.The effects of d-orbital hybridisation on the geometry of the halides ofGroups 11,111, and IV have been investigated.10 Some reviews of generalinterest have appeared on inorganic chain molecules,11 on redistribution andexchange reactions,l2 and on the intercalation of metals in graphite and inmetal chalcogenides 13 MX,.1 (u) V.Gutmann, F. Mairinger, and H. Winkler, Monatsh., 1965,96,524; (6) R. C.Paul, S. C. Ahluwalia, and S . S . Pahil, Indian J . Chem., 1965, 3, 300; (c) R. C. Paul,K. C. Malhotra and 0. C. Vaidya, ibid., p. 1 ; ( d ) I. M. Semenova and A. A. Osipov,J . Gen. Chem. (U.S.S.R.), 1964, 34, 2723; ( e ) S. J. Kuhn and J. S. McIntyre, Canad.J . Chem., 1965, 43, 375, 995.2 ( a ) W. Sundermeyer, Angew. Chern., 1965, 7'7, 241; ( b ) R.S. Drago and K. F.Purcell, Progr. Inorg. Ghena., 1964, 6, 271.3 ( a ) G. W. A. Fowles, Progr. Inorg. Chena., 1964, 6, 1; (b) R. A. Walton, Quart.Rev., 1965, 19, 126.4 E. L. Muetterties and C. M. Wright, J . Amer. Chem. SOC., 1964, 86, 5732; ibid.,1965, 87, 4706.ti H. A. Skinner, Adv. Organometallic Chcnz., 1964, 2, 49.* P. M. Treichel and F. G. A. Stone, Adv. Organometallic Chem., 1964, 1, 143.s " Industrial Synthesis and Application of Organometallics ," Ann. New YorEOthers are referred to in the main text.E. L. Muetterties, Pure Appl. Chem., 1965, 10, 53.B. Siegel, Quart. Rev., 1965, 19, 77.Acad. Sci., 1965, 125, Art. 1, pp. 4-248.34, 13.lo 0. P. Charkin and M. E. Dyatkina, J . Struct. Chem., 1965, 5, 415; 854; 858.*l H.A. Andrianov, I. Haiduc, and L. M. Khananashvili, Russ. Chem. Rev., 1965,l2 J. C. Lockhart, Chem. Rev., 1965, 65, 131.l3 W. Riidorff, Chimia (Switz.), 1965, 19, 489JOHNSON, PADDOCK AND WARE: THE TYPICAL ELEMENTS 133Group 0.-The fluorination of krypton in an electrical discharge14 givesKrF,, not KrF, as reported earlier. Xenon difluoride, shown to be linearby its vibrational spectra,14J5 is formed from the element and fluorides ofoxygen ;I6 its association with xenon tetrafluoride in XeF,,XeF, is electro-static in origin, and depends on charge migration to flu0rine.l‘ Xenon hexa-fluoride forms the complexes18 XeF,,2SbF5, XeF,,SbF,, and 2XeF,,SbF5 ;an electron-diffraction study on the free XeF, molecule shows that it does nothave full octahedral symmetry.19 Xenon fluorides occur as intermediatesin those reactions of perfluoroalkanes which are photosensitised by xenon.20Reactivity with olefins decreases21 in the order XeF, > XeF, > XeF,.Reactions of the noble gases,22a and especially of xenon,22b have been reviewed,and the nature of the bonds in the xenon fluorides discussed. Dimericstructures of XeO, octahedra linked through oxygen have been suggested 23for the mono-alkali xenates, typically NaHXeO,,l.SH,O ; the combineddisproportionation and decomposition of the Xe0,4- ion in alkaline solutionstakes place via a complex of mixed oxidation state,24~ and the mechanism ofits reduction by water has been investigated.24b Vibrational analyses25show that the valence force constants of XeOF, are close to those of relatedinterhalogen c o r n p o ~ n d s .~ ~ ~ ~ ~ For xenon tetro~ide,~,~ the bond energyE(Xe:O) is26 21.1 kcal. mole-l. In the oxides, as in the fluorides, the bondenergy is only slightly dependent on the oxidation state of xenon.Group 1.-Alkali metals form stable paramagnetic solutions in hexamethylphosphoramide which are useful synthetically.27 The magnetic suscepti-bilities of dilute solutions of alkali metals in ammonia have been tentativelyexplained in terms of equilibria involving the metal negative ion.28 Fadedsolutions of potassium or rubidium in ethylamine can be regenerated byillumination in the amide absorption region, charge transfer occurring eitherto the alkali-metal (positive) ion or to the solvent.29 The electronic struc-tures of the adducts formed reversibly30 by alkali metals with aromaticl4 F.Schreiner, J. G. Malm, J. C. Hindman, J. Amer. Chem. SOC., 1965, 87, 25.l5 H. H. Claasen, G. L. Goodman, J. G. Malm, and F. Schreiner, J. Chern. Phys.,l6 S. I. Morrow and A. 33. Young, jun., Inorg. Chem., 1965, 4, 759; L. V. Strengl7 J. H. Burns, R. D. Ellison, and H. A. Levy, Acta Cryst., 1965, 18, 11.l8 G. L. Gard and G. H. Cady, Inorg. Chem., 1964, 3, 1745.l9 L. S. Bartell, R. M. Gavin, jun., H. B. Thompson, and C. L. Chernick, J. Chenz.Phys., 1965, 43, 2547.2o G. H. Miller and J. R. Dacey, J. Phys. Chem., 1965, 69, 143-1.21 Tsu-Chia Shieh, N. C. Yang, and C. L. Chernick, J. Amer. Chena. SOC., 1964, 88,503 I *2 2 (a) J. H. Holloway, Progr.Inorg. Chem., 1964, 6, 241; ( b ) J. G. Malm, H. Selig,J. Jortner, and S. A. Rice, Chem. Rev., 1965, 65, 199.23 T. M. Spittler and B. Jaselskis, J. Amer. Chem. SOC., 1965, 87, 3357.24 (a) C. W. Koch and S. M. Williamson, J. Anaer. Chern. SOC., 1964, 86, 5439,(cf. Ann. Reports, 1964, 61, 115); ( 6 ) E. H. Appelman and Rf. Anbar, Inorg. Chena.,1965, 4, 1066.25 (a) G. M. Begun, W. H. Fletcher, and D. F. Smith, J . Chenz. Phys., 1965, 42,2-336; (b) W. A. Yeranos, Bull. SOC. china. belges, 1965, 74, 40’7; (c) ibid., p. 414.26 S. R. Gum, J. Amer. Chenz. SOC., 1965, 87, 2290.27 G. Fraenkel, S. H. Ellis, and D. T. Dix, J . Amer. Chena. SOC., 1965, 87, 1406.28 S. Golden, C. Guttman, and T. R. Tuttle, jun., J. Amer. Chem. SOC., 1965, 87,29 35.Ottolenghi, K. Bar-Eli, and H. Linschitz, J. Amer. C’hem. Soc., 1965, 87, 1809.30 A. Rembaum, ,4. Eisenberg, and R. Haack, J. Amer. Chem. SOC., 1965, 87, 2291.1965, 42, 1229.and A. G. Streng, ibid., 1370.135134 INORUANIU CHEMISTRYhydrocarbons have been reviewed.21 Caesium has been separated from thelighter alkali metals by extraction with 24 a-methylbenzyl)-4-s-butylphenol,by taking advantage of its smaller tendency to hydration.32 The electronspin resonance spectra of the radical-ion complexes of alkali metals witho-dimesitoylbenzene show an unusually high splitting, which is attributed tothe occurrence of partial covalent bonding.33 Some sodium hydride isformed, at high temperatures and pressures, in the reaction between sodiumand water vapour ;34 its dissociation has been studied in the solid state 35 andin solution in s~diurn.~e The derived solubility of hydrogen in the metalagrees with a direct determination a t the solubility limit, but deviates a tlower pres~ures.~7 The nitrosyl formed from potassium and nitric oxide inammonia sg probably contains the cis-hyponitrite ion N2022-, rather thanNO -.Group 11.-Sodium hydride reacts with dimethylberyllium to giveNa(Me,HBe), from which Me,Be,H,, regarded as a mixture, is produced bytreatment with beryllium chloride.Both types of compound are decom-posed by donor molecules, with the formation of (e.g.) Me,B*NMe, and(MeBH*NMe,),. Bridged structures [typically as in (l)] are believed tooccur generally in all these compounds and in their solutions in ether,89@and have been found, as the Be,H, group, in the crystal structure of theetherate of sodium hydrid~diefhylberyllate,~~~ (NaOE t ,) ,(Et ,Be,H ,).Sodium beryllium hydride Na,BeH, is probably also p~lymeric.~gc Ethyl-beryllium hydride has been prepared from diethylberyllium and triethyltin-(IV) h~dride.,~" Beryllium borohydride forms a complex Be(BuiNH,) 4-(BH,), ; beryllium hydride and triphenylphosphine borane Ph,P*BH, areformed40 on decomposition of the complex (Ph,P),Be(BH,),.On the basisof its proton magnetic resonance spectrum, the structure (2) is assigned totrimeric bi~dimethylaminoberyllium,*~ prepared from dimethylamine anddiethylberyllium. The sodium derivative of hexamethyldisilazane reactswith beryllium chloride to form (Me,Si)&*Be*N(SiMe,),, for which vibra-31 E.de Boer, L4dv. Organometallic Chem., 1964, 2, 115.33 B. Z. Egan, R. A. Zingaro, and B. M. Benjamin, Inorg. Chena., 1965, 4, 1055.3 3 B. J. Herold, A. F. Neiva Correia, and J. dos Santos Veiga, J . Amer. Chem. SOC.,s4 C. C. Addison and J. A. Manning, J . Ghem. SOC., 1964, 4887.35 C. C. Addison, R. J. Pulham, and R. J. Roy, J . Chem. SOC., 1965, 4895.36 C. C. Addison, R. J. Pulham, and R. J. Roy, J . Chem. SOC., 1965, 116.37 D. W. McClure and G. D. Halsey, jun., J. Phys. Chem., 1965, 69, 3542.38 N. Gee, D. Nicholls, and V. Vincent, J. Chem. SOC., 1964, 5897.30 (a) N. A. Bell and G. E. Coates, J . Chem. SOC., 1965, 692 (cf. Ann. Reports, 1964,61, 117); (b) G. W. Adamson and If.M. M. Shearer, Chem. Cornm., 1965, 240; (c) N. A.Bell and G. E. Coates, ibid., p. 582.40L. Banford and G. E. Coates, J . Chem. SOC., 1964, 5591.41 N. R. Fetter and F. M. Peters, Cunud. J. Chem., 1965, 43, 1884.1965, 87, 2661JOHNSON, PADDOCK AND WARE: THE TYPICAL ELEXENTS 135tional and proton magnetic spectra indicate both a linear N-Be-N skeleton(in the condensed phase) and planar BeNSi, groups. It does not reactwith strong donors.42 Diethylmagnesium and magnesium bromide reactalmost instantly in ethereal s0lution,4~ to form monomeric EtMgBr. Simi-larly, the precipitate formed by adding triethylamine to the solution isEtMgBr,Et ,N, no redistribution reaction occurring provided the donor isstrong enough.44 Alkaline earth nitride halides (e.g., M a x ) have beenprepared by sintering a mixture of halide and nitride in a nitrogen atmo-~phere.~5 Diacetamide, with salts of alkali and alkaline-earth metals, formscomplexes which appear (by infrared spectroscopy) to have chelate structures ;if all the ligands are bidentate, then the complexes of Ca,Sr,Ba, must beformulated as eight- and ten-co-ordinate.46Methylamine displaces fluoride ion from phosphorustrifluoride-borane PF,*BH, less rapidly than ammonia does, to give(MeNH),PF,_;BH, (x = 1-3).A substitution reaction also occurs withdimethylamine in the absence of a solvent, but in ether the base is dis-placed.47 Carbon monoxide-borane BK3C0, in ether adds methylamineor dimethylamine, the products being 1 : 1 electrolytes in water,48 typicallyMeNH,+[H,BC( O)NHMe]-. Unsymmetrical cleavage of diborane byMe,K or Et3N to form, e.g., [H,B(NH,Me),]+BH,- is favoured by lowtemperatures ;49 dimethyl sulphoxide reacts similarly.50 Bisamineboroniumions can be prepared conveniently by the oxidation of amineboranes withA new type of electron-deficient compound has been discovered inthe manganese carbonyl derivative HMn3( CO),,(BH,) ,, in which the twoborane groups link the three metal atoms through l~ydrogen.~~ The infra-red spectra of the blue-violet paramagnetic salts NiIIA(BH,),, where A is atetraclentate ligand, suggest that the borohydride ion is here bidentate.53aAluminium borohydride reacts with up to four donor molecules L, the finalproducts being53b LOBE, and LmAlH,.Alkynyl boranates Na[R,BC:CR’]and Na,[R,BC:CBR,] have been synthesised 54 from alkynes and sodiumtrialkylboranates.Triborane and tetraborane derivatives have been de-tected in the pyrolysis of diborane.55 The synthesis of a deuterium-labelledtetraborane p-B,H,D has been reported,56 and tetraborane-( 10) has beenGroup IlI.--Boron.4 2 H. Biirger, C. Forker, and J. Goubeau, Moraatsh., 1965, 96, 597.43 M. B. Smith and W. E. Becker, Tetrahedron Letters, 1965, 3843.4 4 E. C. Ashby, J . Amer. Chern. Xoc., 1965, 87, 2509.46 H. H. Emons, D. Anders, G. Roewer, and F. Vogt, 2. anorg. Chena., 1964, 333,46 P. S. Gentile and T. A. Shankoff, J . Inorg. Nuclear Chem., 1965, 27, 2301.4 7 G. Dodema and R. W. Parry, Inorg. Clzem., 1965, 4, 410.4 8 J. C. Carter and R.W. Parry, J . Amer. Chem. SOC., 1965, 87, 2354.4D S. G. Shore, C. W. Hickam, jun., and D. Cowles, J . Amer. Chem. Soc., 1965, 87,5 0 G. E. McAchran and S . G. Shore, Inorg. Chem., 1965, 4, 125.s1 J. E. Douglass, J . Amer. Chem. SOC., 1964, 86, 5431.62 H. D. Kaesz, W. Fellmann, G. R. Wilkes, and L. F. Dahl, J . Amer. Chem.s3 ( a ) N. F. Curtis, J . Chem. SOC., 1965, 924; (b) P. H. Bird and M. G. M. Wall-64 P. Ringer and R. Koster, Tetrahedron Letters, 1965, 1901.s5 A. B. Baylis, G. A. Presley, E. J. Sinke, and F. E. Stafford, J . Amer. Chem.66 A. D. Norman and R. Schaeffer, Iizorg. Chem., 1965, 4, 1225.99; 1965, 335, 195.2755.Soc., 1965, 87, 2753.bridge, ibid., 3923.Soc., 1964, 86, 5358136 IN 0 R G AN IC CHEMISTRYconverted to the thermally unstable 2- bromo-derivativea57 The molecularstructure (of approximately tetragonal symmetry) of iodopentaborane(9)has been determined,58 and the base-catalysed conversion of 1 - bromopen-taborane(9) into the 2-bromo-isomer has been achieved.5g A new type (3)of organoborane6O has been prepared, by reaction of C,oH8(BC12)4 with(3) (4)LiBH,. Spectroscopic results suggest an octahedral configuration 61 (4)for monocarbahexaborane( 7 ), CB 5H (from 1 -methylpentaborane), and thenew hexahydroborate ion R6HG2-, prepared 62a from diborane and sodiumborohydride, is rigorously octahedral.62a,b Several B5- and B,-organo-carboranes have been found in the products of the reaction between ethyl-diborane and acetylene.63 The two hydrides B,H,, and (the new) BgHIghave been prepared by the decomposition of the B,HI 4- and the B,H,- ions,respectively, with polyphosphoric Hexaborane( 10) gives a1 : 1 adduct with triphenylphosphine, and a carborane Me,C2B6H, withdimethylacetylene;65 improved yields of C2B,H5, 1 ,2-C2B4H6, 1 ,6-C2B,H,,and C2B,H7 have been obtained 66 by the ultraviolet irradiation of 2,3-dicarbahexaborane( S) .The electronic polarisabilities and diamagnetic susceptibilities of n seriesof polyhedral boranes and halogenoborafies can be accounted for in terms ofa conducting-sphere model for the boron cage,,' with additive contributionsfrom the attached groups.IlB nuclear magnetic resonance spectroscopy isan important method for investigating the stereochemistry of polyboranes ;among recent results, the spectrum of B5H1, has been assigned,68a the 1-and 2-monochlorodecaboranes identified,,sb and all the dissimilar hydrogenatoms in B,,HL, distinguished.68C Most of the structural assignments re-ferred to below have been obtained in this way.Nucleophilic attack of amides on decaborane (BloH14) takes place57 J.Dobson and R. Schaeffer, Inorg. Chem., 1965, 4, 593.58 L. H. Hall, S. Block, and A. Perloff, Acta Cryst., 1965, 19, 658.59 A. B. Burg and J. S. Sandhu, J . Amer. Chem. SOC., 1965, 87, 3787.6 o M. Zeldin and T. Wartik, Inorg. Chenz., 1965, 4, 1372.61 T. Onak, R. Drake, and G. Dunks, J . Amer. Chem. SOC., 1965, 87, 2505.62 (a) J. L. Boone, J . Amer. Chem. SOC., 1964,86, 5036; ( b ) R. Schaeffer, Q. Johnson,63 R.Koster and G. W. Rotermund, Tetrahedron Letters, 1965, 777.64 ( a ) H. A. Beall and W. N. Lipscomb, Inorg. Chem., 1964, 3, 1783; ( b ) J. Dobson,65 R. E. Williams and F. J. Gerhar!, J . Amer. Chem. SOC., 1965, 87, 3513.6 6 J. R. Spielman and J. E. Scott, jun., J . Amer. Chem. SOC., 1965, 87, 3512.67 A. Kaczmarczyk and G. B. Kolski, Inorg. Chem., 1965, 4, 665.6 8 ( a ) R. E. Williams, F. J. Gerhart, and E. Pier, Irtorg. Chem., 1965, 4, 1239;( b ) R. E. Williams and E. Pier, ibid., 1357; (c) R. L. Pilling, F. N. Tebbe, M. F. Ham-thorne, and E. A. Pier, Proc. Chem. SOC., 1964, 402; P. C. Keller, D. Maclean andR. Schaeffer, Chem. Comm., 1965, 204.and G. S. Smith, Inorg. Chem., 1965, 4, 917.D. Gnines, and R. Schaeffer, J . Amer. Chem. SOC., 1965, 87, 4072JOHNSON, PADDOCK AND WARE: THE TYPICAL ELEMENTS 137through nitrogen to give preferentially 69 the 6,9-disubstituted derivatives(RCONMe,),B,,H,,. It is likely that the same positions are bridged byAlH,+ and GaH,+ in the new compounds 70 (Me,NH)+(B,,H,,AlH,)- and(Me,NH)+(Bl,Hl,GaH,)-.As a consequence of the electrophilic nature ofthe B,,H,, nucleus, hydrazines RNHsNH, add readily 71 across the nitxilegroups in (MeCN),B,,H,,; the importance of good n-acceptor, as well asn-donor properties in the ligand has been stressed.7, Dimethyl sulphoxidereacts readily under acid conditions with the B,,H,,2- ion, to give first the(dimethyl sulphide) nonahydrodecaborate (-1) ion, substitution occurringmainly in the apical position [see ( 5 ) ] .1,lO-Bis(dimethy1 sulphide)-decaborane(8) is converted on heating to the more stable 2,7-isomer.8 n9[Reproduced, with permission, from W. H. Knoth, W. R. Hertler, and E. L.Muetterties, Inorg. Chem., 1965, 4, 280.1Chlorine substitution on the cage facilitates izucleophilic cleavage of theC-S bond, whereas positively charged substituents decrease the reactivity. 73Czesium tropenylium nonahydrodecaborate, the first member of a new classof organoboron compounds, and bistropenylium octahydrodecaborate 74 havebeen prepared (6). A series of derivatives B,,H,L-, B,,H,L,, B1,H,,L-,M. M. Fein, J. Green, J. Bobinski, and M. S. Cohen, Inorg. Chenz., 1965, 4, 583.iC”. N. Greenwood and J. A. McGinnety, Chem. Comin., 1965, 331.71 M. M. Fein, J. Bobinski, J.E. Paustian, D. Grafstein, and M. 5. Cohen, Inorg.7 2 J. J. Kaufman, J . Ilzorg. Nuclear Chem., 1964, 26, 2165.73 W. H. Knoth, W. R. Hertler, and E. L. Muetterties, Inorg. Chem., 1965, 4, 280.7 4 K. M. Harmon, A. B. Harmon, and A. A. Macdonald, J . Anzer. Chenz. SOC.,Chenz., 1965, 4, 422.1964, 86, 5036138 IN 0 RG A NI C C H E fix1 S TRYB, 2Hl.oL2 (L = sulphone, sulphonamide, urea, nitrile, nitrobenzene, oriodosobenzene) has been prepared by the acid-catalysed reaction of the baseswith the parent anions, typicallyH+ + BiJf1aa- + L + H, + B,oH&-;Oxygen-bonded ligands occupy equatorial, nitriles and iodosobenzene theapical positions.75 Dimethyl sulphide and trimethyl lamine derivatives ofBloH1,2- and B12H122- have been carbonylated with oxalyl chloride, to give(e.g.) 2,4- and 2,7($)-Me,NBl,HC80.The results in general confirm thatB1,HIo2- derivatives are more reactive than B12H1,2- derivatives to electro-philic attack, and also the preference for equatorial substitution, in spite ofthe lower electron densities calculated for these positions.76 Isomerisationoccurs a t high temperatures by polyhedral rearrangements rather than bygroup migrations.77 The N-protonated conjugate acid of the apical derivativeB,,H9N2Ar2- is obtained from B,,HlO2- and an aryl diazonium salt; azo-dyes are formed by cleavage and coupling with a second diazonium salt.'*Substitution of tghe normally inert halogenated ions B10X102-, B12X1 22- bynucleophiles such as CN- can be induced photochemically.79 The reactivityseems (reasonably) to be the inverse of that for electrophilic substitution,substitution going further for B12Br122- than for BloC1,,2-The B,oH182- ion is reduced by sodium in ammonia to B,,H,,4-, inwhich the two polyhedra are joined through equatorial boron atoms(7,eZ).Conversion into the other two forms, ae and a2, is catalysed by acid.80On the basis of kinetic measurements, a mechanism has been suggested 81 forthe attack of OH- on B2,H,82-.The CZB,Hll2- ion, an 1 l-particle icosahedral fragment, undergoes thereactionC,B,HIl2- + PhBCI, -+ PhC,B,oHll + 2C1-,the additional boron atom in the product probably occupying the twelfthicosahedral position in the otherwise open face of C2BgH,,2-. A similarlocation is likely 83 for the metal atoms in the [C,BgHllMn(CO),]- ion (S),[from BrMn(CO), and (C2BgH1,)2-J, in the Fe(C2BgHll)2- and in thecarborane analogues 84* of the cobalticinium ion, for which sandwich struc-tures of two icosahedral fragments are suggested.Piperidine extracts one boron atom from the lY2-carborane C2Bl,H127 5 H.C. Miller, W. R. Hertler, E. 1;. Muetterties, W. H. Knoth, and N. E. Miller,7 6 W. R. Hertler, W. H. Knoth, and E. L. Muetterties, Inorg. Chem., 1965, 4, 288.77 W. R. Hertler, W. H. Knoth, and E. L. Muett.erties, J . Amer. Chem. SOC., 1964,78 33. F. Hawthorne and F. P. Olsen, J . Arner. Chem. SOC., 1965, 87, 2366.5 9 S. Trofimenko and H. N. Cripps, J . Amer. Chem. SOC., 1965, 87, 653.8o M. F. Hawthorne, R. L. Pilling, and P. F. Stokely, J .Amer. Chern. SOC., 1965,M. F. Hawthorne, R. L. Pilling, and P. M. Garett, J . Amer. Chem. SOC., 1965,83 M. F. Hawthorne and P. A. Wegner, J . Amer. Chem. SOC., 1965, 87, 4392.83 M. F. Hawthorne and T. D. Andrews, J. Amer. Chem. SOC., 1965, 8'4, 2496.84 (a) M. F. Hawthorne, D. C. Young, and P. A. Wegner, J . Amer. Chem. SOC.,1965, 87, 1818; (b) M. F. Hawthorne and T. D. Andrews, Chem. Comm., 1965, 443.Inorg. Chena., 1965, 4, 1216.86, 5434.87, 1893.87, 4740JOHNSON, PADDOCK AND WARE: THE TYPICAL ELEXENTS 1391 I267'1'1'Strmctzcre of the three possible B,,H,,-4 isomers in which two BloHQ-2 fragments are joinedby a two-centre B-B bend. [Reproduced, with permission, from M. F. Hawthorne,R. L. Pilling, and P. F. Stokely, J .Amer. Chem. SOC., 1965, $7, 1893.1A possible structure for (B&,Hll)3h(CO),- and (B,C,H,,)Re(CO),- (H atoms have[Reproduced, with permission, from M. F. Hawthorne and T. D. been omitted).Andrews, J . Amer. Chem. Soc., 1965, 8'7, 2496.140 INORGANIC CHEMISTRY(barene) ;8Su in the resulting piperidinium salt of the C,B,H,,- ion, a secondmolecule of the base is present as a hydrogen-bonded ~pecies.8~~ C-Metal-lation of the 1,2-carborane with sodamide occurs readily, further treatmentwith CO, giving 86 the acid (9). Further evidence of the acceptor propertiesof the carborane nucleus is provided by the easy cleavage of the exocyclicC-C bonds in the ester HC=B,,H1,*C*CO,Et (by NaOEt) and in the amideHC(B,,H1,)C*CONMe, (by LiAlH,).87 A study of the properties of sub-stituted phenyl groups Ax in dicarbaclovododecaborane (12) HC( B,,H,,)CArhas provided no evidence for delocalisation over both aryl group and car-borane system in the ground state of the 1,2-compounds, though weakelectron-donation to the phenyl group occurs by delocalisation in the 1,7-compound (neocarborane) .88 Hydroxymethylcarboranes have been used 89for the preparation of exocyclic derivatives such as the phosphate (10). Thecourse of electrophilic substitution on the carborane icosahedron is deter-mined by the positions of the more electronegative carbon atoms. Bro-(9) (10)rnination occurs less readily and completely than chlorination,gO substitutionbeing limited in carborane and neocarborane to HC*B,,H,Br,-CH andHC.B,,H,Br,*CH respectively.g0a The C-H groups are more acidic thanin the parent carborane.The planar anionic layers in ScB,C2 have a tessellated structure of 5- and7-membered rings containing both boron and carbon,gl and such compoundsmay be useful synthetically.Small amounts of B-H compounds have beenobtained by the hydrolysis of alkaline-earth borocarbides 92a MC,B andMC4B2 but not from simple b0rides.~2b The preparation and properties ofheterocyclic organoboranes have been reviewed. 93A further example of cis-trans-isomerism about the B-N bond has beenfound in EtO(Me)B.N(Me)Ph; many other compounds of the type X,B-NY,,s5 (a) L. I. Zakharkiii and V. N. Kalinin, Tetrahedron Letters, 1965, 407; ( b ) 31. F.Hawthorne, P. A. Wegner, and R. C.Stafford, Inorg. Chem., 1965, 4, 1675.86 L. I. Zakharkin, V. I. Stanko, and Yu. A. Chapovskii, Bull. Acad. Sci. U.S.S.R.,1963, 517.L. I. Zakharkin and Yu. A. Chapovskii, Bull. Acad. Sci. U.S.S.R., 1964, 723.88 M. F. Hawthorne, T. E. Berry, and P. A. Wegner, J. Amer. Chenz. SOC., 1965,87, 4746.as J. Green and A. P. Kotloby, Inorg. Chem., 1965, 4, 599; N. N. Schwartz, E.O'Brien, S . Karlan, and M. M. Fein, ibid., p. 661 ; N. Mayes and J. Green, ibid., p. 1082.(a) H. D. Smith, T. A. Knowles, and H. Schroeder, Inorg. Chem., 1965, 4, 107;( b ) L. I. Zakharkin, V. I. Stanko, and A. I. Klimova, Bull. Acad. Sci. U.S.S.R., 1964,722.91 G. S. Smith, Q. Johnson, and P. C. Nordine, Acta Cryst., 1965, 19, 665.9 2 ( a ) L. Ya. Markovskii and X. V. Vekshina, J .Appl. Chem. U.S.S.R., 3'7, 2102,2107; ( b ) N. N. Greenwood, R. V. Parish, and P. Thornton, J . Chein. SOC., 1965, 545.93 R. Koster, Adc. Organonzetallic Chent., 1964, 2, 257JOHNSON, PADDOCK AND WARE: THE TYPICAL ELEMENTS 141both monomeric 94 and dimeric, 95 have been investigated spectroscopically.Isocyanato- and isothiocyanato-boranes have been ~repared,~6 and theazido-derivatives (XB,N,),, (X = GI, Br), have D3h symmetry.97 Severalsymmetrical N-fluor~alkyl-,~~~ B-flu~roaryl-,~~~ and B - t r i e t h y n ~ l - ~ ~ ~ andunsymmetrical N-methyl- 98c and B-propoxy- borazines gsd have been pre-pared by conventional methods. B-Trichloro-N-trhethylborazine reactsnormally with C-lithiocarborane~.~~ A determination of the crystal struc-ture of hexaethylborazine 100 confirms that the ring is planar regular hexa-gonal, and measurements of the heats of hydrolysis of B,H,N&e,,B,H,N,H,, and B,Cl,N,H, show that the B-N bond is weakest in the lastcompound.lol The reduction potentials of phenyl-substituted borazines,determined polarographically, have been related to a molecular-orbitaltheory of their structure.lo2 Borazine B,N3H6 and borazanaphthaleneB,N,H8 take up respectively three and five moles of hydrogen chloride orbromide, the original planarity being lost.The hydrogen halide is eliminatedstereospecifically.lQ3The preparation of some 5- and &membered rings containing carbon aswell as boron and nitrogen has been described.104 1,8,10,9-Triazabora-decalin on reaction with LiMe and Me,N.BClPh gives the boryl derivative(1 la), from which the tricyclic compound (1 lb) is obtained by transaminationwith aniline.NN-Dimethylhydrazine reacts analogously. The triaza-broadecalin ring is expanded by phenyl isocyanate or isothiocyanate to git-0fused %membered ring structures.10594 H. T. Baechle and H. J. Becher, Spectrochim. Acta, 1965, 21, 579.95 A. J. Banister and N. K. Greenwood, J . Chem. SOC., 1965, 153-1.96 M. F. Lappert, H. Pyszora, and M. Rieber, J . Chem. Soc., 1965, 4256.97 P. I. Paetzold, M. Gayoso, and K. Dehnicke, Chem. Ber., 1965, 98, 1965.98 (a) A. Meller, M. Wechsberg, and V. Gutmann, Monatsh., 1965, 96, 388; ( b ) H.Watanabe, T. Totani, and T. Yoshizaki, Inorg. Chem., 1965, 4, 657; (c) A. Meller andR. Schlegel, Monatsh., 1965, 96, 1209; ( d ) A.Meller, R. Schlegel, and V. Gutmann,ibid., 1964, 95, 1564.D9 J. L. Boone, R. J. Brot,herton, and L. I. Petterson, Inorg. Chem., 1965, 4, 910.loo M. A. Viswanlitra and S. K. Vaidya, 2. Krist., 1965, 121, 472.Iol B. C. Smith and L. Thakur, Nature, 1965, 208, 74.Io2 D. F. Shriver, D. E. Smith, and P. Smith, J. Amer. Chem. Soc., 1964, 86, 5153.lo3 A. W. Laubengayer, 0. T. Beachley, jun., and R. F. Porter, Inorg. Chenz., 1965,4, 578.lo4 G. Hesse and A. Haag, Tetrahedron Letters, 1965, 1123; H. Witte, ibid., p. 1127;G. Hesse and H. Witte, Annulen, 1965, 687, 1 ; J. Tanaka and J. C. Carter, TetrahedronLetters, 1965, 329; J. Casanova, jun., H. R. Kiefer, D. Kuwada, and H. A. Boulton,ibid., p. 703.lo5 P. Fritz, K.Niedenzu, and J. W. Dawson, Inorg. Chena., 1965, 4, 886142 INORGANIC CHEMISTRYVery high pressures and temperatures are required for the synthesis ofB20, regarded as a n " unsymmetrical " analogue of graphite.lOg The inter-conversion of boroxine H&O3 and H2B203, believed to have the structure(12), has been studied thermochemically.107 The new thioperboratesMBS,, M2B2S5, (M = Na,K), are less stable to moisture or to heat than theiroxygen analogues.lo8The heat of formation of difluoroborane, prepared from BF3 and bor-oxine, has been determined, and its infrared spectrum and that of HBBr,assigned. O Potassium pentafluor ophen yl trifluoro b ora t e K ( C 6F, BF 3) hasbeen obtained ll0a by condensing pentafluorophenylboron diftuoride 11Ob intoan aqueous solution of potassium fluoride.The 1 : 1 complex BP3,NH20Kis acidic,lll and forms the salt K[BF,ONH,]. Vapour pressures over Br3-fluoroborate-CK,Cl2 mixtures have been interpreted 112 in terms of thecondensed ions B2H7-9 B3H1,-. Co-ordination of BCI, to the oxygen atomof NN-dimethylformamide increases 113 the barrier to rotation about theC-N bond from 6.2 to 14.5 kcal.mole-1. The central bond in B2F4 is split bypropionic acid :114B,F, + 2EtC0,H -+ 2EtCO,BF, + H,.1,2-Bis(dichloroboryl)ethylene is a less good acceptor than the correspond-ing ethane derivative ;l15 partial disproportionation of the methylamineadduct occurs, to form Me3N,BCl,. The mass spectrum of B,Cl, showspeaks characteristic of the progressive removal of chlorine atoms from theparent molecule.116 No B,, peaks were observed for B,,Cl,,, the highestbeing that for BllClll+.Aluminium.Monomeric alane AlH, dimerises readily,l17 and the firstderivative of dialane has been prepared by the reactionTHFMe,N.AlCIH -+ Me,N.Al,H,.NaAlH,Substitution and addition reactions of phenylacetylene a,nd organoalanesR,AlH (R = Me,Et,Ph) are suppressed by triethylamine.ll9 The perfluoro-phenyl derivatives C,F,AlBr, and (C,F,),AlBr are obtained 120 from AlBr,and the mercurial MeHgC,F,, and reaction of lithium aluminium hydride withC6F,Br yields,121 after disproportionation, the benzene-soluble LiAl( C6F5)3Br.The temperature-dependence of the proton magnetic resonance spectra oflog H. T. Hall and L. A. Compton, Inorg.Chem., 1965, 4, 1213.lo' L. Barton, S. K. Wason, and R. F. Porter, J . Phys. Chem., 1965, 69, 3160.lo* F. Chopin and P. Hagenmuller, BUZZ. SOC. chim. France, 1965, 3031.Ion R. F. Porter and S. K. Wason, J . Phys. Chem., 1965, 69, 2208, 2461.110 (a) R. D. Chambers, T. Chivers, and D. A. Pyke, J . Chem. Soc., 1965, 5144;ll1 I. G. Ryss and S. L. Idel's, Russ. J . Inorg. Chem., 1965, 10, 383.112 S. Brownstein and J. Paasivirta, Caiaad. J . Chem., 1965, 43, 1645.113 E. X. Gore, D. J. Blears, and S. S. Danyluk, Canad. J . Chem., 1965, 43, 2135.l l * A . K. Holliday, G. N. Jessop, and F. B. Taylor, J . Chem. SOC., 1965, 1551.116 C. Chambers and A. K. Holliday, J . Chem. Xoc., 1965, 3459.A. G. Massey and D. S. Urch, Chem. and Ind., 1965, 607.117 P.Breisacher and B. Siegel, J . Amer. Chem. SOC., 1964, 86, 5053.l l s A . R. Young, jun., and R. Ehrlich, J . Amer. Chem. SOC., 1964, 86, 5359,llS J. R. Surtees, Austral. J . Chem., 1965, 18, 14.lZo R. D. Chambers and J. Cunningham, Tetrahedron Letters, 1965, 2389lZ1 R. S. Dickson, Chem. Conam., 1965, 68.( b ) R. D. Chambers and T. Chivers, ibid., p. 3933JOHNSON, PADDOCK AND WARE: THE TYPICAL ELEMENTS 143alkylaluminiums indicates breakage of a bridge bond, which is then re-formedwith a digerent alkyl group ; 122a the corresponding redistribution reactionbetween AlMe, and AlEt, is very slow in pyridine.122b The benzlonitrileadducts of R3,!!1 (I3 = Me,Et,Ph) and Me2Al@1 rearrange to the dimericbenzylideneamino-derivative~,~~~~ e .g., (PhMeC:NAlMe,) %.Alkyl cyanidesreact similarly, [ (MeCH:NAlMe,), appears to exist in cis- and trans-forms],but further elimination of a hydrocarbon can occur, to give polymericThe (dimeric) phosphinoalane (Et,Al.PPh,), has also beenprepared.124 The electrochemistry of organoaluminium compounds has beenre~iew6d.l~~ Measurements of the conductivity of adducts of organo-aluminium compounds with Lewis bases provide evidence for solvatedAlX,+ ions, and blue aluminium-containing radicals have also been obtainedelectrolytically.126 In the complex [Al(OPri)3]2,C,H4(NH,)2, rapid ex-change of the alkoxy-groups takes place both within the molecule and withthe s01vent.l~' On the basis of freezing-point measurements, it is sug-gested128 that aluminium dissolved in AlBr, or All, may be present asdi-atoms or the associated dimers A14Br, and A&.Gallium, Indium, and Thallium.Nuclear magnetic resonance spec-troscopy using 'lGa shows, among other that two types of galliumatom are present in GaCl, and GaBr,. Complexes of GaI have been inves-tigated by Raman spectroscopy,130 and In+ has been detected polarogra-phically as an intermediate in the electrolytic oxidation of indium,131 Gal-lane and jndane, studied rnass-spectrometrically in a flow system, aremonomeric (unlike NH,, and contrary to earlier reports) .132 The complexesMe,N,GaH,-,X, (X = Cl,Br,I,n = 0-3) have been prepared from thesimple gallane adducts and the hydrogen halides;l33 GaH,Cl is displaced fromits trimethylamine complex by BF,.The more st'able dichlorogallane,synthesised according to the equationMe,SiH f GaC1, + Me,SiCl + RGaC1,is (unlike gallane itself) dimeric in benzene; it decomposes to Ga(GaC1,) onheating.134 Organometallic compounds behave comparably to the hydridesin that wit,hin the group, only the alkyls of aluminium are associated;l35aPhGaX,, Ph,GaX, on the other hand, form halogen-bridged dimersin benzene.13jb Methane can be eliminated from the complexes of122 (u) K. C. Ramey, J. F. O'Brien, I. Hasegawa, and A. E. Borchert, J . Phys. Chem.,1965, 69, 3418; (b) T. Mole, Austral. J . Chem., 1965, 18, 1183.123 ( a ) J. E. Lloyd and K. Wade, J . Chem. SOC., 1965, 2662; (b) J. R. Jennings, J. E.Lloyd, and K. Wade, ibid., p. 5083.13* A. W. Johnson, W. D. Larson, and G.H. Dahl, Canad. J . Chem., 1965, 43, 1338.125 Yu. M. Kessler, N. Bl. Alpatova, and 0. R. Osipov, Russ. Chem. Rev. 1964, 33,119.las H . Lehmkuhl and H. D. Kobs, Tetrahedron Letters, 1965, 2505; H. Lehmkuhl,G. Fuchs, and R. Koster, ibid., p. 2511.127 V. J. Shiner, jun., and D. Whittaker, J . Amer. Chern. Soc., 1965, 87, 843.128 J. Thonstad, Canad. J . Chem., 1964, 42, 2739.lZD J. W. Akitt, N. N. Greenwood, and A. Storr, J . Chem. SOC., 1965, 4410.l 3 0 L. A. Woodward and M. J. Taylor, J . Inorg. Nuclear Chem., 1965, 27, 737.131 R. E. Visco, J . Electrochem. SOC., 1965, 112, 932.132 P. Breisacher and B. Siegel, J . Amer. Chem. SOC., 1965, 87, 4255.133N. N. Greenwood and A. Storr, J . Chem. SOC., 1965, 3426.134H. Schmidbaur, W.Findeiss, and E. Gast, Angew. Chem., 1965, 7'7, 170.135 ( a ) N. Muller and A. L. Otermat, Inorg. Chem., 1965, 4, 296; (b) P. G. Perkinsand M. E. Twentyman, J . Chem. Xoc., 1965, 1038144 INORGANIC CHEMISTRYMe,M (M = Al,Ga,In) with primary and secondary aliphatic phosphines, togive e.g., (Me,Ga*PMe,),, which forms six-membered rings in s01ution.l~~Complexes of the type [M(diars),X,][MX,] (M = GaT1l,Inlll) areformed from halides of the metal and a ditertiary arsine.13' The unusualanions Ga,Cl,,- and In(diars)I,- are formed from GaCl, and 1111,; for theformer, a bridged structure (13) is suggested.Indium(II1) also forms six-co-ordinate cationic complexes with bidentateligands such as 2,2'-bipyridy1;138 other complexes of Inrrr have beenstudied .I39Thallic chloride forms the chlorothallate ion TlCl,- with the halides oflarge univalent cations, and T1C13,2py with pyridine.The thallic complexTl(Et,N*CS,), is a non-conductor, and is presumably trichelate.l40 Thefluorothallate(rrr) compounds (Li,Na)T1F4 have a fluorite-type structure,and do not contain TlF,- ions.lel Raman spectra of aqueous TllI1 chloridecomplexes show the presence of T1C12+, TlCl,', TlCl,, TiCl, -, and TlC163-, butno polymeric species ; comparison with the crystal spectra suggests that bothtetrahedral and octahedral structures are distorted by interaction with waterm01ecules.l~~Bis(pentafluorophenyljthallium(I1J~ bromide (C6F,),T1+Br- gives 1 : 1complexes with bidentate ligands, in which the metal may be five-co-ordinated.With halides of large cations, the anions [(C6F,),T1X,]- areformed.143 On the basis of its vibrational spectra t,he cation [Me,Tl,py]f isbelieved to be T-shaped.14,Group IV.-Carbon. Thorium mono- and di-carbides give hydrogen,C,-C, alka,nes and unsaturated hydrocarbons with aqueous alkali.145 Inter-calation compounds of Li,Na,K have been obtained from graphite and thenaphthalene complexes of the alkali metals in tetrah~drofuran.14~ A phase-change in graphits nitrate has been recognised as being due to '' melting '' of atwo-dimensional layer.l4' The energetics of the polymerisation of dicyano-gen have been reviewed.l4*136 0. T. Beachley and G. E. Coates, J . Chem. SOC., 1965, 3241.137 R. S. Nyholm and K. Ulm, J . Chem. SOC., 1965, 4199.laeA.J. Carty and D. 0. Tuck, J . Chem. SOC., 1964, 6012.139 D. G. Tuck and E. J. Woodhouse, J . Chem. SOC., 1964, 6017; E. N. Deichman,G. V. Rodicheva, and P. A. Chel'tsov, RUSS. J . Inorg. Chem., 1965,10, 48; E. K. Deich-man and L. S. Krysina, ibid., p. 256.140 F. A. Cotton, B. F. G. Johnson, and R. M. Wing, Inorg. Chem., 1965, 4, 502.lol R. Hoppe and C. Hebecker, 2. amrg. Chem., 1966, 335, 85.142 T. G. Spiro, Inorg. Chem., 1965, 4, 731, 1290.14s G. B. Deacon, J. H. 8. Green, and R. S . Nyholm, J . Chern. Xoc., 1965, 3111.144 I. R. Beattie and P. A. Cocking, J . Chem. Xoc., 1965, 3860.M. J. Bradley, M. D. Pattengill, and L. M. Ferris, Inorg. Chern., 1965, 4, 1080.lo6 C. Stein, J. Poulenard, L. Bonnetain, and J. Go16, Compt. rend., 1965, 260, 4503.A.R. Ubbelohde, G. S. Parry, and D. Nixon, Nature, 1965, 206, 1352.148 H. J. Rodewald, Chem.-Ztg., 1965, 89, 522JOHNSON, PADDOCK AND WARE: THE TYPICAL ELEMERTSSiticon.145Simple and substituted silanes form clathrate compounds withurea and thiourea which may be useful for their ~eparati0n.l~~ Iodosioaneforms complexes with pyridine and alkylpyridines which are formulated as(L,SiH,)+I-, and a 1 : 1 adduct (Me,NSiH,)+I- with trimeth~1arnine.l~~On the basis of its vibrational spectra, P(SiH,),, like N(SiH,),, is at leastclose to planarity, the lone pair on the central atom contributing to 3pz-3dzbonding ;151a by contrast, p3t-dn bonding is not stereochemically significantin trigermyl phosphine 151b P(GeH,), 0rl51c in GeH,NCO.The similarity ofthe ultraviolet spectra of phenanthrene and silazarophenanthrene ( 14) alsosuggests the use of &orbitals by silicon.152 The stability of the silylcobaltcarbonyls R,SiCo(CO), formed in the reaction of Co,(CO), with eitherSiH,I(R = H)15Za or R,SiH(R = Cl,Ph)153b is ascribed (as for similarphosphine derivatives) to d,-d, bonding.153b Evidence for electron releaseto silicon is provided by the measurement of the dipole moments of alkylsilyl derivatives,154a the electronic 154b and proton magnetic resonancespectra 154c of phenylsilanes and their derivatives, and by the detailed inter-pretation 154d of the electron spin resonance spectra of biphenyl radical ions(Me3X*C6H,*C6H5)-, (x = Si,Ge). Again, germanium withdraws electronsless effectively than does s i 1 i ~ o n .l ~ ~ ~ Configuration is retained in the cleav-a’ge of a substituted disilane by lithium.155 The chemistry of organo-substituted cyclosilanes has been reviewed.lS6Many new silicon-nitrogen compounds have been made, and their usein further preparative reactions in~estigated.1~7, Particularly usefulreactions involve the elimination of either amines, e .g. ,I59a2R3SiNHR’ ---+ (R3Si)2NR’ + R’NH,,or of trimethylsilyl chlorides :15gbMe,SiNH*SiMe, + Me,SiCl, -+ Me,SiNH*SiMe,Cl + Me,SiCl.As with boron-nitrogen compounds, either linear or cyclic compounds can beprepared by transarninati~n.~~~~ The sodium derivative of hexamethyl-disilazane (Me,Si),NNa reacts with carbon dioxide and with carbon disul-phide togive the cyanamide derivative 160a Me,SiN:C:NSiMe,, and [ (RO),Si],N149 R.Muller and G. Meier, 2. anorg. Chem., 1964, 332, 81, -381; 1965, 337, 268.150 B. J. Aylett and R. A. Sinclair, Chena. and In&., 1965, 301.151 (a) G. Davidson, E. A. V. Ebsworth, and G. M. Sheldrick, Chem. Conzm., 1965,122; ( b ) S. Cradock, G. Davidson, E. A. V. Ebsworth, and L. A. Woodward, ibid.,p. 515; ( c ) J. E. Grfiths and A. L. Beach, ibid., p. 437.152 J. M. Gaidis and R. West, J. Amer. Chem. SOC., 1964, 86, 5699.153 (a) B. J. Aylett and J. M. Campbell, Chem. Comm., 1965, 217; ( b ) A. J. Chalkand J. F. Harrod, J . Amer. Chem. SOC., 1965, 87, 1113.154 (a) V. N. Krishnamurthy and S. Soundararajan, J . Inorg. Nuclear Chern., 1966,27, 2341; ( b ) L. Goodman, A.H. Konstam, and L.H. Sommer, J . Aqner. Chem. SOC., 1965,87, 1012; (c) R. Waack and M. A. Doran, Chem. and Ilnd., 1966, 563; ( d ) M. D. Curtisand A. L. Allred, J. Amer. Chem. Soc., 1965, 87, 2554.lS5 L. H. Sommer and R. Mason, J . Amer. Chem. Soc., 1965, 87, 1619.156 H. Gilman and G. L. Schwebke, Adv. Organonaetallic Chem., 1964, 1, 90.15’ E. W. Abel and D. A. Armitage, J . Chem. SOC., 1964, 5975.15*K. Ruhlmann, A. Reiche, and M. Becker, Chem. Ber., 1965, 98, 1814.159 (a) U. Wannagat, P. Geymeyer, and E. Bogusch, Xonatsh., 1966, 96, 585;( b ) J. Silbiger and J. Fuchs, Inorg. Chem., 1965, 4, 1371; ( c ) C. H. Yoder and J. J.Zuckerman, &id., p. 116.16* (a) U. Wannagat, H. Kuckertz, C. Kruger, and J. Pump, 2. anorg. Chem., 1964,333, 54; ( b ) U.Wannagat, K. Behmel, H. Wolf, and H. Burger, ibid., p. 62146 INORGANIC CHEMISTRYis obtained from [(RO),Si],NNa, by successive treatment with silicontetrachloride and the alcohol.ls@ Dichloro(phtha1ocyanino)silicon is con-veniently synthesised from SiC1, and either o-cyanobenzamide or 1,3-di - iminoisoindolineAlkylpolysiloxancs substituted by fluorine in the a- and /?-positions aresensitive to heat and alkali, whereas the y-derivatives are stable to both.162The reaction of aluminium chloride with dimethylsiloxanes leads to mole-cules in which the groups -Me,SiO- and -AlClO- alterr~ate,l~~ and hetero-ailoxanes of zinc, cadmium, mercury, and thallium(@ have been preparedfrom organometallic compounds and silanols or silanolates,l64 typicallyMe,SiONa + MeHgCl + Me,SiOHgMe + NaCl.The infrared spectra of a series of disiloxanes 165a shows that the partialp,-d, bonding is strongly dependent on the nature of the substituents.Asimple treatment 165b of the vibrational spectra of X,O, (X = Si,P,S,CI)molecules suggests that z-bonding is strongest in the silicon compounds.The force constants and interbond angles, taken as a sensitive measure ofppn-dra bridge bonding, have been discussed critically,165c and the importanceof polarising cations in increasing p n 4 , bonding and the XOX angle inX20, anions has been s t r e s ~ e d . l ~ ~ ~ , ~ Organosilyl sulphides are formed fromalkylchlorosilanes, typically according to the reactionMeSMgI + Me,SiCl ---+ MeSSiMe, + MgICl;the corresponding germyl compounds are better prepared from a germylhalide (e.g., Ph3GeBr) and a mercaptan in the presence of pyridine.166Polymeric Sip, is obtained by condensing at -196" the product of the re-action of silicon with SiF,; perfluorosilanes Si,$2n+2 (n = 1-14) are pro-duced by its destructive distillation, and the compounds SiF,( SiF,),BF,,(n = 1,2,3), have been isolated from the reaction of the monomer with borontrifluoride.l67 Polymeric SiCI,, also, is formed 168 in a reaction betweensilicon a,nd SiC1,.Calcium silicide CaSi, reacts with iodine monochloride to give169a thehighly-coloured, layer-structured, (SiCl),, in which the chlorine can bereplaced by methyl or alkoxy-groups. The aminopolysilanes 169b, arenon-stoicheiometric, and contain unpaired electrons.161 31.K. Lowery, A. J. Starshak, J. N. Esposito, P. C. Krueger, and M. E. Kenney,Inorg. Chem., 1965, 4, 128.162 T. N. Bell, R. N. Haszeldine, M. J. Kewlands, and J. B. Plumb, J. Chem. SOC.,1965, 2107; R. N. Haszeldine, M. J. Newlands, and J. B. Plumb, ibid., 2101.163 D. Cordischi, A. Mele, and A. Somogyi, J. Chem. Soc., 1964, 5281.164 F. Schindler, H. Schmidbaur, and U. Kriiger; H. Schmidbaur and F. Schindler,Arzgew. Chem., 1965, 77, 865.165 (a) G. Engelhardt and H. Kriegsmann, 2. anorg. Chem., 1965,336, 286; ( b ) R. J.Gillespie and E. A. Robinson, Canad. J. Chem., 1964, 42, 2496; (c) A. N. Lazarev,BUZZ. Acad. Sci. U.S.S.R., 1964, 218; ( d ) A. N. Lazarev and T. F. Tenisheva, ibid.,166 K. A. Hooton and A. L. Allred, Inorg.Chem., 1965, 4, 671.167 P. L. Timms, R. A. Kent, T. V. Ehlert, and J. L. Margrave, Nature, 1965, 207,187; P. L. Timms, T. C. Ehlert, J. L. Margrave, F. L. Brinckman, T. C. Farrar, andT. D. Coyle, J . Arner. Chem. SOC., 1965, 87, 3819.168 M.. Schmyisser and P. Voss, 2. anorg. C h . , 1964, 334, 50; P. W. Schenk andH. Blochmg, sbsd., p. 57.169 (a) E. Hengge and G. Scheffler, Monatsh., 1964, 95, 1461; (b) E. Hengge andU. Brychly, 2. anorg. Chem., 1965, 339, 120; (c) E. Hengge and G. Schemer, Monatsh.,1964, 95, 1450.p. 379JOHNSON, PADDOCK AND WARE: THE TYPICAL ELEMENTS 147Spectroscopic evidence supports the cisoctahedral codguration forSiF,,Z(amine) adducts7170a and the tram-configuration 170b for SiF4,2Ph,P0.Infrared spectroscopy and conductivity measurements suggest that the1 : 4 adducts, e.g., Si(C10,),,4Ph3PO, contain the cation [Si(Ph,PO)4]4+.Themethyl fluorosilicate ions (SiMe,F,-,)2-, (n = 1,2,3) have been synthesisedfrom Me4NF and the appropriate fl~orosi1ane.l~~Trichlorogermane, HGeCl,, is acidic, and can be used forthe preparation 1 7 2 of chlorogermanites MGeC1, (M = NH,,K,Rb,Cs) ; it canbe methylatedl73 with tetramethyltin to give methyldichlorogermaneMeGeC1,H. Thermally stable compounds R,GePPh2 and R,Ge(PPh,), areformed from the appropriate halide and lithium diphenylphosphide ; they arehydrolysed to the digermoxane (R,Ge) ,O and diphenylphosphine, andoxidised to R,Ge*O*P( O)Ph,. Germanes carrying more halogen atoms formwater-stable polymeric dipheny1pho~phinogermanes.l~~ A study by protonmagnetic resonance spectroscopy of the mobile equilibrium between Me2GeX,(X = C1,BrJ) and either Me,Ge(SMe), or (Me,GeS), has shown that theinterchange process is non-random; in the first system, mixed speciesMe,Ge(X)SMe predominate, and in the second, trimeric (Me,GeS), is themost abundant compound in a mixture of rings and chains.17j A new pre-parative method for the cyclic compound (GePh,), (from diphenylgermane)has been described.The ring is opened by iodine to give I(GePh,),I, whichforms the linear derivative Ph( GePh,) ,Ph with phenyl-lithium, and whichis hydrolysed to the cyclic ether (15). The cyclic compounds (GePh,) 5,6Germa.iLium.EtI \ Ph,Ge, ,GePh,0 (I 5 )Me2Sn /N\ SnMezi IEtN, ,NEtSnMe2 (16)have also been prepared.176 The tetrahdides of germanium, tin, and leadform 1 : 1 adducts with bipyridyl, with the exception of GeI,, which forms a1 : 2 ndduct formulated as (bi~y,GeI,)~+, 21-.Terpyridyl gives the ioniccomplexes (terpy,MI,)+I-, (M = Ge,Sn). All the cations contain the 6-co-ordinated metal; the 1 : 1 terpyridyl complexes with Ph,PbX, are undis-sociated.177Tin. The species Snl?,- and Sn,F,- predominate in the molten systemsMF-SnF, (M = Na,K,Rb,Ca), as they do in aqueous solution.178a Various170 (a) H. Burger, W. Sawodny, and F. Hofler, Monatsh., 1965, 96, 1437; ( b ) I. R.171 J. J. Moscony and A. G. MacDiarmid, Chem. Comm., 1965, 307.172 I. V. Tananaev, B. F. Dzurinskii, and Yu. N. Mikhailov, Russ. J . Inorg.Chem.,173 V. F. Mironovana and A. L. Kravchenko, J . @en. Chem. (U.S.S.R.), 1964, 34,174 E. H. Brooks, F. Glocking, and K. A. Hooton, J . Chem. SOC., 1965, 4283.175 K. Moedritzer and J. R. Van Wazer, J . Amer. Chem. Xoc., 1965, $7, 2360.176 W. P. Neumann and K. Kiihlein, Annalen, 1965, 683, 1.177 J. E. Fergusson, W. R. Roper, and C. J. Wilkins, J . Chem. SOC., 1965, 3716.17* ( a ) J. D. Donaldson, J. D. O'Donogue, and R. Oteng, J . Chena. SOC., 1965, 3876;Beattie and M. Webster, J . Chem. SOC., 1965, 3672.1964, 9, 862.1359.( b ) J. D. Donaldson and J. F. Knifton, ibid., 1964, 6107148 INORGANIC CHEMISTRYspecies have been found in solutions of complex tin formate~,17~~ but thesolids obtained are all derivatives of the triformatostannate(r) ionESn(CHO2) ,I-*Many of the reactions of compounds of tin(1v) depend on the cleavage of apola’r covalent bond from tin; organotin hydrides can act as either electro-philic 179a or nucleophilic 179b reagents. Aldehydes and ketones react withstannanes, to give alkoxytin compounds in good yield; e.g.,NN-Dialkylstannylamines are obtained similarly from trialkyltin hydridesand azomethines.lsO On the other hand, hydrogenolytic fission of Sn-Nbonds by dialkyl- or diaryl-tin hydrides gives a monohydride, e.g.,R,SnNPh*CHO + R’,SnH, + R,SnSnR‘,H + PhNHCHO.Linear tri-, tetra-, penta-, and hexa-tine derivatives have been prepared bysimilar reactions,181 and also from organotin hydrides and oxides,1S2 e.g.,2Bu,SnH + Bu,SnO + Bu[SnBu,],Bu + H20.Alkylstannanes are decomposed by hydrogen bromide to give hydrogen andpolytin derivatives; with arylstannanes the Sn-C bond is broken in prefer-en~e.18~ The preparation of several aryl- and perfluorophenyl-derivativesof Snxv has been reported;ls4 reaction of tetraphenyltin with fluorides ofboron or phosphorus is thought to yield salts of the Ph,Sn+ Distan-nazanes, like disilazanes, are formed in the elimination reaction2R,SnNHR’ + (R,Sn),NR’ + R’NH,,a.nd the cyclic trimer (16) has been synthesised by a method involving bothelimination and transamination.186 In contrast to related compounds ofsilicon, however, alkylthio-compounds of tin(Iv), R,SnSR’, R,Sn(SR’), andRSn(SR’), can be prepared in aqueous s01ution.l~~ Cyclic and spiro-derivatives have been obtained, as well as a sulphonium salt (Me,SnSMe,)+I-.Dipolar double bonds, (C:C, C:N, C:O, S:O, S:N) undergo addition reac-tions with stannylaminesl88a (e.g., Me,Sn-NMe,), stannylphosphines,188bPh,SnPPh, + CS, + Ph,Sn*S*CS*PPh,and with dibutyltin oxide.188c Tin( ~ v ) alkoxides add exothermally acrossthe carbonyl bond in aldehydes, and since the product is also a tin alkoxide,high polymers R’,Sn(OCHR),OR’ are eventually formed by an (‘ insertion ”mechanism .lS9R,CO + R’,SnH + R,CH.OSnR’,.179 ( a ) H.M. J. C. Creemers and J. G. Noltes, Rec. Tn7v. chim., 1965, 84, 500;180 W. P. Neumann and E. Heymann, Annalen, 1965, 683, 11, 24.lS1 H. M. J. C. Creemers and J. G. Noltes, Rex. Truv. chirn., 1965, 84, 382.lS2 A. K. Sawyer, J. Amer. Chem. SOC., 1965, 87, 537.183 G.Fritz and H. Scheer, 2. anorg. Chem., 1965, 338, 1.lS4 ( a ) R. D. Chambers and T. Chivers, J. Chem. SOC., 1964, 4782; ( b ) J. Burdon,lS5 D. W. A. Sharp and J. M. Winfield, J. Chem. SOC., 1965, 2278.lS6 K. Jones and M. F. Lappert, J. Chem. SOC., 1965, 1944.18’ E. W. Abel and D. B. Brady, J. Chem. SOC., 1965, 1192.lS8 (a) T. A. George, K. Jones, and M. F. Lappert, J. Chem. SOC., 1965, 2157; ( b ) H.Schumann, P. Jutzi, and M. Schmidt, Angew. Chem., 1965,77,912; ( c ) A. J. Bloodworthand A. G. Davies, Chena. and Ind. 1965, 900.1*9 A. G. Davies and W. R. Symes, Chem. Comn., 1965, 25.(b) A. J. Leusink and J. G. Noltes, ibid., p. 585.P. L. Coe, and M. Fulton, ibid., 1965, 2094JOHNSON, PADDOCK AND WARE: THE TYPICAL ELEMENTS 149Dimethyldichlorostannane reacts with carboxylic acids and phenols togive distannoxane~~~~ of the type (R’Me,Sn),O, (R’ = RCO,, PhO).Theoccurrence of 4-, 5- and 6-co-ordination in organotin compounds has beendiscussed on the basis of spectroscopic evidence.lg1 Five-co-ordinated tinappears to be present lg8 in the complexes R,Sn(Ox)X, (R = Me,Ph;Ox = 8-quinolinyl; X = C1,I). Several compounds of the type R,Sn(Ch),,where Ch is a chelating ligand, have been prepared,l93 and also salts of thethiocyanatomethylstannate ionslg4 [Me,Sn(SCN),-,],- (x = 1,2,3). In com-plexes of the type (R,SnL,), (R = Me,Ph; L is bidentate),195a and195b in[Me,Sn( 0H),l2-, spectroscopic results show that the C-Sn-C skeleton islinear, the s-orbital contribution being maximised in the bonds to carbon.Some disproportionation to a trimethyltin species occurs in aqueous solu-tionThe nitrate groups in tin(1v) nitrate are probably bidentate lg6 (on infraredevidence), as in [Co(N03)J2-, the metal being eight-co-ordinated, but theyare unidentate in the complex py2,Sn(N03),. The configuration of a numberof octahedral complexes of tin(rv) fluoride is cis where n-bonding with theligand is likely, ( Ph3P0, MeCN), but trans otherwise (tetrahydrofuran,Me3N).lg7 Stannic fluoride reacts with the fluoride ion to give the octa-hedral anions SnF,B-, provided the solvent (B) is a strong enough baseto prevent the formation of fluorine bridges.198 The existence of cis- andtrans-[SnF,( OH) ,I2- and [ SnF3( OH),]2- in labile and statistical equilibriumwith [SnF,OHI2- has been established by 19F nuclear magnetic resonancespectroscopy.199 Stannic chloride also forms both cis- and trans-di-adducts ;diethyl sulphicle complexes more strongly than diethyl ether.200a A trans-configuration has been found crystallographically2OOb in tetrachlorobis( tetra-hydrothiophen) tin( IV) .cis-Complexes are formed with chelating carboxylicanhydrides 201a and with carboxylic acids,201b in which the ligand is probablya half-opened acid dimer. The complexes Sn(Acac)(OMe)X, (X = Cl,Br,I)are dirneric, and possibly involve methoxy-bridges.202 The preparation ofthe oxyhalidea SnOX, (X = F,Cl,Br) and of SnF,CI, and S11F,(ON02), hasbeen described. O3The Pb2T ion forms weak Complexes with (preferentially) even Lead.l90 &I.Ohara, R. Okswara, and Y . Nakamura, Bull. Chem SOC. Japan, 1965, 38,lS1 R. Okawara, J . Chena. SOC. Japan, 1965, 88, 543.lS2 A. H. Westlake and D. F. Martin, J . Inorg. Nuclear Chena., 1965, 27, 1579.193 W. H. Nelson and D. F. Martin, J . Inorg. Nuclear Chem., 1965, 27, 89.lS4 A. Cassol, R. Portanova, and R. Barbieri, J . Inorg. Nuclear Cheni., 1965, 27,lS5 (a) M. M. McGrady and R. S. Tobias. J . Anaer. Chern. Soe., 1965, 87, 1909; ( b )lS6 C. C . Addison and W. B. Xinipson, J . Chern. SOC., 1965, 598.lS7 C. J. Wilkins and H. M. Haendler, J. Chem. SOC., 1965, 31i4.lS8 R. 0. Ragsdale and B. B. Stewart, Inorg. Chem., 1965, 4, 740.lS9 P. A. W. Dean and D. F. Evans, Proc. Chem. SOC., 1964, 407.* O 0 ( a ) I.R. Beattie and L. Rule, J . Chent. SOC., 1965, 2995; ( b ) I. R. Besttie, R.201 ( a ) P. Hunt and D. P. N. Satchell, J . Chena. SOC., 1964, 5437; (b) D. P. N. Satchel1202 Y. Kawasaki and R. Okawara, J . Inorg. Nuclear Chem., 1965, 27, 1168.go3 K. Dehnicke, Chent. Ber., 1965, 98, 280, 290.1379.2275.Re. S. Tobias and C. E. Freidline, Inorg. Chern., 1965, 4, 215,Hulme, and L. Rule, ibid., p. 1581.and J. L. Wardell, Tram. Paraday SOC., 1965, 61, 1132150 INORGANIC CHEMISTRYnumbers of chloride ions in aqueous solution.2w The triphenylplumbyl-methane derivatives CR,, CHR,, and CH2R2, (R = Ph,Pb), have beenobtained 205 from the appropriate chloromethane and LiPbPh,. The newcompounds Ph3(CGF,)Pb, Me,(C,F,)Pb, and (C,F',),Pb have been preparedfrom pentafluorophenyl magnesium halides and R,PbCl (R = Ph,Me) andPbC1, respectively.206Oxidation of ammonia by alkaline hypobromite 2 ~ 0 7 ~yields predominantly the bromo-amines NH,Br and NHBr, ; nitrogentribromide is formed preferentially at pH < 6.Di-imide N2H2 has beenidentified 207b as an intermediate in the alkaline decomposition of NH2C1,through its hydrogenating action on multiple bonds, and organic chloro-amines have been converted 207c into the corresponding azides R2N*N, andthiocyanates R,N(SCN)3-, (n = 0-2). The reaction between iodine andammonia has been re-investigated.20idFor steric reasons, the symmetry of (CF,) ,N*N( CF,), approximates toD2d, so enhancing z-bonding between the nitrogen atoms, and shorteningthe N-N bond.208 Methylation of the dilithio-derivative 209 of 1,2-bis(trime-thylsily1)hydraxine gives both the 1,2-dhethyl derivative and the isomeric(Me,Si),N*NMe,.Azidocarbodinitrile NCN.NCN has been prepared by the pyrolysis ofcyanogen azide, and may exhibit cis-trans-isomerism ;210 the vibrationalspectra of CF2N2 are interpreted 211 as evidence for the cyclic structure (17).Group V.-Nitrogen./c\F, N=N (17)On the basis of infrared spectra, co-ordination of the azides R3MN3(R = Me,Ph; M = Si,Ge,Sn) to Lewis acids 212 is believed to take placethrough the nitrogen atom attached t,o M.Nitramide has been prepared by the ammonolysis of nitrogen p e n t ~ x i d e .~ ~ ~Bis(trifluoromethy1)hydroxylamine has been oxidised 214 to the new, purple,gaseous radical bis( trifluoromethyl) nitroxide (CF,),NO, which is stable toalkalis.Dimerisation occurs on solidification. The adduct of diethylamine2 0 4 G. P. Haight, jun., and J. R. Peterson, Inorg. Chem., 1966, 4, 1073.205 L. C. Williamsens and G. J. M. Van der Kerk, Bec. Trau. chim., 1965, 84, 43.206 D. E. Fenton and A. G. Massey, J . Inorg. Nzcclear Chena., 1965, 27, 329.207 ( a ) H. Galal-Gorchev and J. C. Morris, Inorg. Chm., 1965, 4, 899; ( b ) E. Schmitz,R. Ohme, and Q. Ihzakiewicz, 2. anorg. Chem., 1965, 339, 44; (c) H. Bock and K.-L.Kompa, ibid., 1964, 332,238; E. Allenstein and E. Lattewitz, ibid., 333, 1; (d) J. Janderand U. Engelhardt, ibid., 1965, 339, -225.208 L. S. Bartell and H. K. Higgmbotham, Inorg. Chena., 1965, 4, 1346.209 R.E. Bailey and R. West, J . Arner. Chem. Xoc., 1964, 86, 5369.211 C. W. Bjork, N. C. Craig, R. A. Mitsch, and J. Overend, J . Amer. Chem. Soc.,212 J. S . Thayer and R. West, Inorg. Chem., 1965, 4, 114.213 P. Vast and J. Heubel, Compt. rend., 1965, 260, 5799.211 W. D. Blackley and R. R. Reinhard, J . Arner. Chem. SOC., 1965, 87, 802.F. D. Marsh and M. E. Hermcs, J . Amer. Chem. Soc., 1965, 87, 1819.1965. 87, 1186JOHNSON, PADDOCK AND M7ARE: THE TYPICAL ELEMENTS 151with nitric oxide decomposes in oxygen, the reaction being formulated as :215[Et2NH,]+[Et2N*N,0,]- + +02 -+ [Et2NH2]+N0,- + Et,N*NO.Nitrosonium nitrate NOSNO,- has been isolated by the oxidation of NO a t79*K, and it is concluded 216 that the stabilities of the isomers of N,O, de-crease in the order 0,N*N02 > NO+N03- > ONO*NO,.A detailed mole-cular-orbital study of O,N*NO suggests that the formation of the centralBond involves delocalisation of z-electrons from oxygen into an antibondingN-N 0rbital.21~ Dinitrogen tetroxide removes some of the water cleanlyand rapidly from salt hydrates;2l8 e.g., KAl(S0,),,12H20 loses 6H20. Theexistence of the complex HN0,,2HC1O4 has been confirmed by therma,l andX-ray analysi~.~1~The difluoramicle ion decomposes in alkaline solution :22*(ferric ions promote the formation of tetmfluorohydrazine N2P,). Similarly,the complexes formed 221 by difluoramine with alkali-metal fluorides ME'(M = K,Rb,Cs) decompose Z2Ia to difluorodiazine :2MF + 2HNF, --+ 2MHF, + N2F2.Fluorination of sodium azide gives a mixture of cis- and trans-difluoro-diazine;222u a good yield of the tmns-isomer is obtained by decomposition of3??,F, + 2AlC1, + 3N2F, + 3C1, + 2A1F3.cis-Difluorodiazine forms a 1 : 1 complex with ASP, which is formulated223aionically as the hexafluoroarsenate of the hitherto unrecognised cationN,F+ ; the trans-isomer does not react.cis-Difluorodiazine also bothdeoxygenates and fluorinates oxides and oxyflu~rides.~~~~ Chlorodifluora-mine ClMF, has been prepared by the chlorination of HNF, in the presenceof potassium or rubidium and by the combined action of fluorineand chlorine on sodium a ~ i d e . , , ~ ~ Arsenic triffuoridc is displaced by N2F4from its complex with SbF,, to form22z NE,,SbF,. The chemistry of thefluorides of nitrogen hams been reviewed.226Difluorophosphine has been prepared 227 by the reactionNF2- + F- 4- &N,F,N2F4 :22ZbPhosphorus.PF21 + HI + 2Hg + PF2H + Hg,I,.215 R.0. Ragsdale, B. R. Karstotter, and R. S. Drago, Inorg. Chem, 1965, 4, 420.216 L. Parts and J. T. Miller, jun., J . Chenz. Phys., 1965, 43, 136.217 R. D. Brown and R. D. Harcourt, Austral. J . Chem., 1965, 18, 1115.218 C. C. Addison and D. J. Chapman, J . Chem. Soc., 1965, 819.219 A. Potier, J. Potier, and D. Rousselet, Compt. rend., 1965, 261, 4115.220 K. J. Martin, J. Amer. Chem. SOC., 1965, 87, 394.221 (a) E. A. Lawton, D. Pilipovich, and R. D. Wilson, Inorg. Chem., 1965, 4, 118;(b) H. E. Dubb, R. C. Greenough, and E. C. Curtis, ibid., p. 648.222 (a) A. V. Pankratov, 0.M. Sokolov, and N. I. Savenkova, Rws. J . Inorg. Chem.,1964, 9, 1095; (b) G. L. Hurst and S. I. Khayat, J . Amer. Chem. SOC., 1965, 87, 1620.223 (a) D. Moy and A. R. Young, jun., J . Amer. Chem. SOC., 1965, 87, 1889; (b) M.Lugtig, Inorg. Chem., 1965, 4, 104.2 2 4 ( a ) 137. C. Firth, jun., Inorg. Chem., 1965, 4, 254; (b) A. V. Pankratov and 0. 0.Zherebina, Rws. J . Inorg. Chem., 1964, 9, 1096.225 J. K. Ruff, J . Amer. Chem. SOC., 1965, 87, 1140.226 C. B. Colburn, Endeavour, 1965, 24, '138.227 R. N. Rudolph and R. W. Parry, Inorg. Chem., 1965, 4, 1339152 IN 0 RC AN I C CH E MI S TRYOrganophosphines containing pentafluorophenyl groups have been syn-thesised ;120, 228 alkylphosphines carrying dialkylamidogroups are quarter-nised only a t phosphorus.229 Ligand exchange with PCl, takes place morerapidly with P(NCS), than with P(NCO),; exchange is much slower betweenthe corresponding oxy-~ompounds.~~0 Tetrachlorodiphosphine P,Cl, hasthe trans-structure in the solid, liquid, and vapour phases,231 in contrast toP21,, which is tmns in the solid, but gauche in solution.The latter compoundreacts with bromine and with BBr, to give PBrI, and P,I,,2BBr3 respec-ti~ely.~32 The diphosphines and diarsines R,(P,As), are cleaved to giveR ,( P,As)H by lithium aluminium h~dride,~33" and linear phosphines con-taining up to four phosphorus atoms are formed when the ring structure ofEt,P, is opened by an alkali metal or by phenyl-lifhi~m.~33b The crystalstructures of pentameric 234a and hexameric234b phosphobenzene (PhP),,( n = 5,6), have been determined, the molecules containing rings of five andsix phosphorus atoms respectively.Two more crystal modifications ofphosphobenzene are Phosphobenzene forms 1 : 1 and 1 : 2 com-plexes with cuprous halides 235a and the compounds 235b (PhP),(Mo,W)( CO),with the metal liexacarbonyls. The preparati0n,~~5c by the same method, of(PhP),M(CO),, (M = Cr,Mo,W) and the related compounds of arsenic,(PhAs),Mo(CO), and (PhAs),[Mo(CO),],, has been reported; cis-substitu-tion is indicated by their infrared spectra. Nickel carbonyl 235b gives(PhP),Ni(CO), ; ring expan~ion2~5b or contraction 2sQc may occur in the for-mation of some of these derivatives. The heats of reaction of arylphosphineswith diborane and the dipole moments of the boranes so formed are consistentwith some B-P pc- dn bonding.236 Dimeric and trimeric phosphinoborines(R,PBR',),,, (R = Et,Bu; R' = F,CI,Br,Pr) are formedz3' by eliminationof Me3SiR' from the borane adducts (Me,SiPR,)BR',. Halogens displacehydrogen from the BH, groups of P- hexaphenylcyclotriphosphinoborine.238The new phosphinoamines RN[P(CF,),],, (R = Me,H) have been pre-pared by condensation of (CF3),PC1 and (CF,),PNHR with trimethylamine.The sodium salt NaN[P(CF,),], is converted239 by (CF3),PC1 into the tertiaryphosphinoamine N[P(CF,) ,I3.The elements of hydrogen fluoride are easilyeliminated from compounds containing the > CF-PH- group, and reactionof the resulting phospha-alkene > C = P- or > COP- with (e.g.) ammonia228 M.Fild, 0. Glemser, and I. Hollenberg, Natzwuhs., 1965, 52, 590.22s 9. H. Cowley and R. P. Pinnell, J. Amer. Chent. SOC., 1965, 87, 4454; cf. A. €3.230 E. Fluck, F. L. Goldmann, and K. D. Rumpler, 2. anorg. Chern., 1965, 338, 5%;231 S. G. Frankiss and F. A. Miller, Spectrochim. Acta, 1965, 21, 1235.232 A. H. Cowley and S. T. Cohen, Inorg. Chern., 1965, 4, 1200, 1221.233 (a) K. Issleib, A. Tzchach, and R. Schwartzer, 2. anorg. Chenz., 1965, 338, 141;{b) E. Fluck and K. Issleib, ibid., 1965, 339, 274.234 (a) J. J. Daly, J . Chem. SOC., 1964, 6147; ( b ) ibid., 1965, 4789; (c) J. J. Daly andL. Maier, Nature, 1965, 208, 383.235 (a) D. G. Hicks and J. A. Dean, Chem. Comna., 1965, 171; (b) H. G. Ang, J. S.Shannon, and B.0. West, ibid., p. 10; (c) G. W. A. Fowles and D. I<. Jenkins, ibid.,p. 61.236 M. A. Frisch, H. G, Heal, H. Mackle, and I. 0. Madden, J . Chern. SOC., 1965, 899.23' H. Noth and W. Schragle, Chem. Ber., 1965, 98, 352.238 W. Gee, J. B. Holden, R. A. Shaw, and B. C. Smith, J . Chena. SOC., 1965 3171.23s A. B. Burg and J. Heners, J. Ainer. Chenz. SOC., 1965, 87, 3092.- +Burg and P. J. Slota, ibid., 1958, 80, 1107.E. Fluck, H. Binder, and F. L. Goldmann, ibid., p. 58JOHNSON, PADDOCK AND WARE: THE TYPICAL ELEMENTS 153affords a new route into phosphorus-nitrogen ~hemistry.~40niethy1)phosphinyl chloride has been prepared 241 by the reactionsBis( trifluoro-NO, Me,NH HCI(CF,),P + (CF,),PO -+ (CF,),PO*NMe, -+ (CF,),PO-CI.A bicyclic hydrazodiphosphine (18) has been prepared by the transamina-tion of tris(dimethy1amino)phosphine with 1,2-dimethylhydrazine hydro-chloride.242 Monophosphazenes RN:PPh(NHR) and some (PhP), a.reproduced in the pyrolysis of di( alkylamino)phenylph~sphines.~~~Aminosilanes and silazanes are useful in the synthesis of phosphorus-nitrogen compounds.The difunctional heptamethyldisilazane (Me,Si) ,NMegives the four-membered ring (19) with PCl,, whereas the trimeric and te-PhPh\ ,P=N,Jph 1NCLP-NMe1 1MeN-PCt(1 9)trameric compounds (EtN-PC1) ,, are obtained if N-ethylhexamethyldisi-lazane is used.244 A similar reaction with phosphorus pentafiuoride 24ij yieldsthe diazadiphosphetidine (MeN*PF,) ; the chlorine stoms in (PhN:PCI,)can be replaced successively by dialkylarnido-gr~ups.~~~ Several new com-pounds containing -N:PC13 groups, especially derivatives of hydrazine, havebeen obtained in Kirsanov reactions.247Silazanes have also been used248 in the preparation of phosphonitriles, e.g.,(Me,Si),NH CsFPh,PF, - [Ph,PF*NH], -+ [Ph,PN],.- HFThe pyrolysis of aminophosphoniuw salts is also an increasingly usefulsynthetic method.Dialkylchlorophosphines R ,PCl, (R = Me,Et,Bu,) reactwith a mixture of ammonia and chloramine to form the salts [R,P(NH,),]+Cl-,[R2P(NH2)*N*P(NH2)R2]+C1-, which give a mixture of alkylphosphonitriles(R2PN)3,4 on pyrolysis.249 Phenylphosphonitriles (NPPh2)3, are obtainedfrom a related P-N-P intermediate,250a from 250b [Ph2P(NH2)C1]+PC16-, andby heating dimethylhydrazinodiphenylphosphine.250c Reaction of sodium240 H.Goldwhite, R. N. Haszeldine, and D. G. Rowsell, Chem. Comm., 1965, 83.241A. B. Burg and A. J. Sarkis, J . Amer. Chem. SOC., 1965, 87, 238.212 D. S. Payne, H. Noth, and G. Henniger, Chem. Comm., 1965, 327.243 A. P. Lane and D. S . Payne, Proc. Chem. Soc., 1964, 403.244 E. W. Abel, D. A. Armitage, and G. R. Willey, J . Chem. SOC., 1965, 57.245 R. Schmutzler, Chem. Comm., 1965, 19.z4sV. Gutmann, C. Kemenater, and K. Utvary, Manatsh., 1965, 96, 836.247 M. Becke-Goehring, W. Hanbold, and H. P. Latscha, 2. anorg. Chem., 1964,333, 120; M. Becke-Goehring and W. Weber, ibid., p. 128; H.-P. Latscha, W. Hanbold,and M. Becke-Goehring, ibid., 1965, 339, 82; M. Becke-Goehring and W. Weber, ibid.,p. 281.24a R.Schmutzler, 2. Naturforsch., 1964, lob, 1101.249 H. H. Sisler and S. E. Frazier, Inorg. Chem., 1965, 4, 1204.250 ( a ) I. T. Gilson and H. H. Sisler, Inorg. Chem., 1965, 4, 273; (b) M. Becke-Goehring and W. Hanbold, 2. anorg. Chem., 1965, 338, 305; (c) M. Winyall and R. H.Sisler, Inorg. Chenz., 1965, 4, 655.154 INORGANIC CHEMISTRYazide with a mixture of Ph2PC1 and PhPC1, gives mainly the tetraphos-phonitrile (20, R = Cl); other derivatives (R = O€€,OEt,OPh) have beenreported, and diols give polymeric products.251 A mixture of chlorophos-phazenes is obtained 252 by the action of chlorine on phosphorus thionitrideThe rate of the reaction of hexachlorocyclotriphosphazene with piperidinefollows mixed second- and third-order kinetics, and is catalysed by tributy-lamine.253 A geminal substitution pattern has been established for thereaction with t - b u t ~ l a m i n e ; ~ ~ ~ with dimethylamine, both geminal and cis-and trans -non- g eminal subst it u tion occurs.255 Disubst i t u t ion of non- geminalmethylamino-groups occurs exclusively in the cis-orientation ; some of thegeminal derivative is also formed.256 The Friedel-Crafts phenylation ofN3P,C1, is accelerated if formation of the conjugate acid of the phenylderivative is prevented;257 unequal ring bond lengths have been found 258 in2,2-diphenyl-4,4,6,6-tetrachlorocyclotriphosphazatriene. Thephenylationofalkylaminophosphonitriles takes place n~n-geminally,~~~ and cis-truns-isomerisation of non-geminal chloroalkylamino- 259a and chlorophenyl259bderivatives is catalysed by AlCl,.NsP3Cl6-n (Oh),(h = Ph,p-BrC6Ha; n = 1-6) takes place non-geminally;260a,b the cis-cis-trans-configuration has been established260u for N,P,Cl,( OPh),.Thespiro-derivative tris-(o-pheny1enedioxy)phosphonitrile trimer forms crystal-line inclusion compounds with organic solvents.261 Replacement of some orall of the chlorine atoms in N3P3C16 by ally1amine,262u alkylamines,262balcohols,262C d i ~ l s , ~ ~ ~ ~ thiocyanate,262e and thiourea 262t has been reported.Hexachlorotriphosphazene forms complexes with pyridine and stannicchloride,263@ and with aminopho~phazenes.~6~b On spectroscopic evidence,264the planar structure of N,P,C16 in solution is distorted in the crystal, inagreement with the detailed structure determinations.Effects of the solventPNS),.Substitution in the series25lD. L. Herring and C. M. Douglas, Imrg. Chem., 1965, 4, 1012.252 S. N. Nabi, S . N. Nabi, and N. K. Das, J . Chem. Sac., 1965, 3857.26s B. Capon, K. Hills, and R. A. Shaw, J . Chem. SOC., 1965, 4059.264 S. K. Das, R. Keat, R. A. Shaw, and B. C. Smith, J . Chewa. SOC., 1965, 5032.266 H. Koopman, F. J. Spruit, F. Van Deursen and J. Bakker, Rec. Trav. chim.,256 C. T. Ford, F. E. Dickson, and I. I. Bezman, Inorg. Chem., 1965, 4, 890.257 E. T. McBee, K. Okuhara, and C. J. Morton, Inorg. Chem., 1965, 4, 1672.265 N. V. Mani, F. R. Ahmed, and W. H. Barnes, Acta Cryst., 1965, 19, 693.259 (a) R. Keat, R. A. Shaw, and C. Stratton, J . Chem. Soc., 1965, 2223; ( b ) B.Grushkin, M.G. Sanchez, M. V. Ernest, J. L. McClanahan, G. E. Ashby, and R. G.Rice, Inorcq. Chern., 1966, 4, 1538.260 (a) C. T. Ford, F. E. Dickson, and I. I. Bezman, Inorq. Chem., 1965, 4, 419;( b ) D. Dell, B. W. Fitzsimmons, and R. A. Shaw, J . Chem. SOC., 1965, 4070; (c) V. B.Tolstoguzov, V. V. Pisarcuko, and V. V. Kireev, Raw. J . Inorg. Chm., 1965, 10, 382.261H. R. Allcock and L. A. Siegel, J . Amer. Chem. SOC., 1964, 88, 5140.262 (a) H. R. Allcock, P. S . Forgone, and K. J. Valan, J . Org. Chem., 1966, 30,947; j b ) A. F. Nikolaev and Er-Ten Wan, J . Gen. Chem. (U.S.S.R.), 1964, 34, 1843;(c) ibzd., p. 1846; ( d ) S. M. Zhivukhin and V. V. Kireev, ibid., p. 3169; ( e ) N. I. Shvetsov,K. A. Nuridzanyan, A. Ya. Yakubovich, and F.F. Sukhov, ibid., p. 3874; (f) A. V.Babaeva and G. V. Derbisher, Rzcss. J . Inorg. Chm., 1965, 10, 156.2sa (a) S. M. Zhivukhin and V. V. Kireev, Rzcss. J. Inorg. Chem., 1964, 9, 1439;(b) S . K. Das, R. A. S h w , and B. C. Smith, Chm. Comm., 1965, 176.264 I. C. Hisatsune, Spectrochim. Acta, 1965, 21, 1899.1965, 84, 341; R. Keat and R. A. Shaw, J . Chem. Soc., 1965, 2215JOHNSON, PADDOCK AND WARE: THE TYPICAL ELEMENTS 156on the spectra of (NPCl,),,, have been determined,265 and new vapour-pressure results presented for crystals of these molecules and for 266 (NPBr2)3.There is little difference between the basicities of corresponding members ofthe two series ( PY ,) 3,4, (Y = OR,SR ; R = alkyl,aryl), though theteOramer is often the slightly stronger base.267Treatment of N,P,CI, with phenylmagnesium bromide results (in part)in ring contraction, the compound (21) being formed.268 Configurationsa’’ %ahave been assigned to three out of a possible four isomeric phenyl-N-dimethylaminotetraphosphonitriles.2~~ Decabromopentaphosphonitrile 270(NPBr,), and the medium-ring derivatives 271 (NPY,)5-8, (Y = OMe,OPh,OCH,CF3,NMe2) have been prepared, and features of their proton magneticresonance spectra discussed.The molecular structure of [NP(NMe2),16 hassome similarity to that of the tetrameric chloride, and large angles a t bothring and exocyclic nitrogen atoms suggest appreciable electron release tophosphor~s.~7~ The rate of exchange of s6C1- with the chlorophosphoni-triles (NPCI,),, (n = 3-45) is of the first order in each reactant; the re-activity, which decreases in the order n = 4 > 5 > 6 > 3, is not whollyexplicable in terms of ring flexibility.273 The tetrameric chloride is alsomore reactive than the trimer to substitution by a m i n e ~ .~ ~ ~ The heats ofpolymerisation of the chlorides (NPCl,) indicate that stability increaseswith ring size.274The six-membered rings in the trimetaphosphimate ion275a [NH-PO,],S-and in the related cyclotriphosphazane 275b [MeN*PO-OMe], are found to havechair, and slightly twisted boat forms respectively ; the tetrametaphosphi-mate ion [NlEcP02],4- is t ~ b - s h a p e d , ~ ~ ~ ~ with approximate 4 symmetry.Ring bond-lengths and the angles a t the ring nitrogen atoms in all threemolecules suggest the presence of n-bonding in the ring, arising from thedelocalisation of the nitrogen lone-pairs.266 N.B. Jurniski, C. C. Thompson, jun., and P. A. D. de Maine, J . Inorg. NucJear266 S. Cotson and K. A. Eodd, J. Inorg. NzlcZeur Chem., 1965, 27, 335.207 D. Fealrins, W. A. Last, N. Neemuchwala, and R. A. Shaw, J . Chem. SOC., 1965,268 M. Biddlcstone and R. A. Shaw, Chem. Comm., 1965, 205.269 J. H. Smalley, F. E. Dickson, and I. I. Beeman, Imrg. Cltem., 1964, 3,G. E. Coxon, D. B. Sowerby, and G. C . Tranter, J . Chem. SOC., 1965, 5697.271 G. Allen, D. J. Oldfield, N. L. Paddock, F. Rallo, J. Serregi, and S. M. Todd,87a A. J. Wagner and A. Vos, Rec. Trav. chim., 1965, 84, 603.273 D. B. Sowerby, J . Chem. Soc., 1965, 1396.w4 J.K. Jacques, M. F. Mole, and N. L. Paddock, J. Chem. SOC., 1965, 2112.*76 (a) R. Olthof, T. Migchelsen, and A. Vos, Actu Cqst., 1965, 19, 596; ( b ) G. B.Ansell and G. J. Bullen, Chem. Comm., 1965, 493; (c) T. Migchelsen, R. Olthof, and A.Vos, Acta Cryst., 1965, 19, 603.Ohm., 1965, 27, 1571.2804.1780.Chem. and Ind., 1965, 1032156 INORUANIC CHEMISTRYTriphenylphosphine oxide is reduced to the phosphine by organo-boranes ;276a the corresponding reaction with trichlorosilane is stereo-specifi~.~~6* The conditions for the effective preparation of the oxychloridesP,OZn- lC1,+ have been investigated,277 and the synthesis of oxide-halides,including those of phosphorus, has been reviewed.27s The structures ofP,O, and P,Og are derived from that of P,Ol, by the omission of terminaloxygen atoms.279The specific importance of the cation in determining the configurationof the anion in p-M2P207 (M = Mg,Zn) has been emphasised;280a in themagnesium salt, the anion is statistically linear280* above 68".A study,(by 31P magnetic resona.nce spectroscopy), of the interaction of cations withlinear and cyclic phosphates, favours electrostatic binding at fixed sites.281aThe stability of calcium complexes of polyphosphate ions increases withchain length up to about the heptaphosphate ;281b the hydrolysis of thepentaphosphate ion to trimetaphosphate and orthophosphate is catalysedby cupric chelate complexes.281c The cyclic trimetaphosphate ion (P309)3-is cleaved reversibly by ammonia, methylamine, or fluoride ion.282 Thehexametaphosphate ion (P6019)6-, which is resistant to hydrolysis,383a ischair-shaped, with C2h symmetry.283b The tetramethoxyphosphonium ionhas been isolated as its hexachloroantimonate.2s4 The configuration of thefive oxygen atoms bound to phosphorus in the penta-oxyphosphorane formedby the addition of phenanthrenequinone to tri-isopropyl phosphite isapproximately trigonal bip~ramidal.~~5Tetraphosphorus heptasulphide P,S7 loses sulphur preferentially from theterminal positions, with slight shortening of the P-P bond.2*6 The structureof tetraphosphorus triselenide287 is similar to that of P,S,.Nuclear mag-netic resonance studies288a of tetramethyldiphosphine disulphide Me4P,S sug-gest that the two phosphorus atoms are joined through sulphur, though a bandbelieved to correspond to P-P stretching has been found in a re-determinationof the Rainan spectrum of this, and related compounds.288b In the newthiotrifluoromethylphosphines (CF,),PSR, [R = H, Me, But, P(CF,),] and276 ( a ) R.Koster and Y. Morita, Angew. Chem., 1965, 77, 589; (b) L. Horner andW. D. Balzer, Tetrahedron Letters, 1965, 1157.277 (a) G. Muller-Schiedmayer and H. Harnisch, 2. anorg. Chem., 1964, 333, 260;(b) K. Dehnicke, Chem. Ber., 1965, 97, 3358.278K. Dehnicke, Angew. Chem., 1965, 77, 22.279 K. H. Jost, Ada Cryst., 1964, 17, 1593; D. Heinz, 2. anorg. Chem., 1965, 336,137.380 ( a ) C. Calvo, Canad. J . Chm., 1965, 43, 1139, 1147; (b) A. N. Lazarev and T. F.Tenisheva, Bull. Acad. Sci.U.S.S.R., 1964, 224; (cf. Refs. 165c, d.).281 (a) M. M. Crutchfield and R. R. Irani, J . Amer. Chem. SOC., 1965, 87, 2815.( b ) M. Miura and Y. bfonguchi, BUZZ. Chem. SOC. Japan, 1964, 37, 1522; (c) ibid., 1965,38, 678.282 W. Feldmann, 2. Chem., 1965, 5 , 26; 2. aiwrg. Chem., 1965, 338, 235.zs3 (a) E. J. Griffith and R. L. Buxton, ITnorg. Chem., 1965, 4, 549; (b) K. H. Jost,Acta Cryst., 1965, 19, 555.284 J. S. Cohen, Tetrahedron Letters, 1965, 3491.W. C. Hamilton, 8. J. La Placa, and F. Remirez, J . Anaer. Chm. Soc., 1965,87, 127.286 D. T. Dixon, F. W. B. Einstein, and B. R. Penfold, Acta Cryst., 1965, 18, 221.287 K. Irgolic, R. A. Zingaro, and M. Kudchdker, Inorg. Chem., 1965, 4, 1421.288 (a) R. K. Harris and R. Q. Hayter, Canad. J.Chem., 1964,42,2282; (b) H. Gerding,D. H. Zijp, F. N. Hoop, G. Blasse, and P. J. Christen, Rec. Truv. chim., 1965, 84,1274JOHNSON, PADDOCK AND WARE: THE TYPICAL ELEMENTS 157CF,P(SMe),, the electronegative CF, groups prevent the occurrence of theArbuzov rearrangement. Unlike the corresponding oxygen compound, thethiophosphinous acid (CF,)&'SH has some tendency to condense to[(CF,),PJ,S, a-bonds from phosphorus to sulphur being weaker than thoseto 0xygen.28~PCW, and of 290b CCl,*PF,X, (X = Cl,Br) hasbeen described. Axial P-F bonds are found 291a~* in the molecules PCl,F,PCl,F,, and PCIJ?,, and2Qb in MePF,; some n-character is suggested for theaxial bonds on the basis of fQF magnetic resonance spectra,2@la The vibra-tional spectra282 of the methyl chlmphosphoranes PMe,cI,, show thatthese cornpun& am phosphonhim dts (PMe,CI,,J+Cl- (la = 14).Alkyl- or axyl-di~la~ot~uorophosphoranw remange thus 99,2RPF8*NR't + WPF(NR',)J+ IRPFJ-,.The complexw formed by PF, with a number of donor molecules2" aresimilar to analogous compounds of BF3.Substitution of fluorine in PF6 byalkyl and asyl groups reduces acceptor strength drastically, although theRP'E5- ion his been identified.2s5 The 1 : 1 adduct of NOT and PhPF,reaots with secondary amines as follows:-NOF*PhPF, + ZR@ + RP-NO + JR&H,]+[PhPF5]-whioh auggesb an ionic formulation NO+PhPF,- for the initial adduct.296Ar8efik. The (new) alkoxybis( tfiuorornethy1)arsines 2@7 (CF,)&OR,(R = Me,But), do not undergo the Arbuzov rearrangement, owing to thelow basicity of arsenic; on the other hand, As-0 n-bonding is weak, andallows the formation of an adduct with BF,.The reaction of As20, withSiF, at high temperatures can be used2Q* to prepare AsF,. In contrast tothe reaction with PCl,, only two chlorine atoms in AsC1, am replaced byamin0silanet3.~~~ It has been shown by nuclear magnetio resonance apectro-scopy that reorganisation reactions in solutions of As203 in As(OMe), orAs(NMe,), occur rapidly; labile polymeric species AsC1S-n(NMe)nf2 areformed in the AsC1,-As,(NMe), s~~stem.~99bMixed crystals (As,P),O,, isostructural with As2O6, have been obtainedby evaporation of the mixed acids?O0 Thallous tetrameta-arsenate isisomorphous with the corresponding phosphate.301The anion of empirical composition ASFIO-, previously believed to beThe preparation of**BA.B. Burg and K. Gtosling, J . A ~ T . Chem. Soc., 1965, 87, 2113.*SO (a) R. P. Carter, jun., and R. R. Holmes, I m g . Chem., 1965, 4, 738; (b) J. F.Nixon, J . Inorg. Nuckmr Chm., 1965, 2'7, 1281.**a (a) R. R. Hohes, R. P. Carter, jun., and a. E. Peterson, Inmy. Cbm., 1964,8,1748; (b) R. R. Holmes andR. P. Cater, jun.,J. C k . Plqp., 1965,48,1645; (0) A. J.Downa and R. Schmutzler, 8pectpochim. A&, 1966, €31, 1927.n@a R. Baumgiirtner, W. Sawodny, aad J. Coubeau, 2. a w g . Ohm., 1964,888,171.a@*R. Schmutzler, J . Chm. Soc., 1966, 5630.a@41. K. Gregor, Chem. a d I d . , 1966, 385.E. L. Muetterties and W. Mahler, Inorg. Chem., 1965, 4, 119.**@R.Schrnutzler and (3. 8. M d y , I w g . Cham., 1965, 4, 191.2B7 A. B. Burg and J. Singh, J . Amr. Ohm. Soc., 1965, 87, 1213.**eK. 0. Chris& and A. E. Pavlath, J . C h . Soc., 1966, 827.a@B (a) K. Moedritzer and J. R. Van W~lzer, I w g . Cbm., 1965, 4, 893; (b) J. R.a*oA. Winkler and E. Thilo, 2. anmg. Cham., 1965, 889, 71.801 K. Dosbl and V. Kocman, 2. Chem., 1965, 5, 344.Van Wazer K. Moedritzer and M. D. Ransch, J . Chem. Phys., 1965, 42, 3302158 INORUANIO CHEMISTRYtrimeric, is now f0rmulated3~~ as a, h e r (22). Trimethyl arsenafe reactswith n-propylamine to give 303 the pentamethyl ester As(OMe),. The threenew compounds Ph3AsBr,, PhAsIBr,, and Ph3As13Br ionise as halogeno-triphenylarsonium trihalides in methyl ~yanide,~M and the formulation ofhF3C12 as [AsCl,]$-[AsE’,]- has been verified by vibrational spectroscopy.305Antimony and Bismuth.Antimony trichloride, which can be preparedsimply306 by heating Sb2S3 with anhydrous CuCl,, is a weaker acceptor toamines than are stannic or zinc chlorides.307Tetrameric imido-compounds (RNeSbY),, (Y = 1,OEt) of antimony(m)are obtainedSo8 by reaction of SbY, with alkylamines; aromatic amines givethe imides Sb,(NR),. A crystal structure determination shows that potas-sium antimony1 tartrate is a derivative of the antimonite ion [Sb(OH),]-, themetal being co-ordinated by four oxygen atoms at the corners of a deformedtrigonal bipyramid, one equatorial position being occupied by an unsharedpair of electrons.309a In ,8-Sb204, the SbIn atoms have a similar environ-ment, the SbV atoms being octahedrally co-ordinated.In conjunction with hydrogen fl~oride,~lO SbF, is a stronger acid thanBF,.Ligand exchange in the SbF,-SbCl, system is rapid, but the equili-brium is complicated by polymerisation and i ~ n i s a t i o n . ~ ~ ~ On the basis of itsRaman spectra, SbFCl, is found to have the trigonal bipyramidal shape insolution, but to be ionic, [SbCl,]+F-, in the crystal.31a Binuclear fluoroanti-monates [F,Sb(02)SbFJ2- [cf. (22)] and [F,SbOSbF,]- are formed bythermal condensation of hydroxyfl~oroantimonates.~~~ Alkali thiocyanato-bismuthates(m) containing the ions [Bi(SCN),]-, [Bi(SCN),I3- have beenprepared. 314The superoxide ion 0,- has been obtained by theelectrolytic reduction of 0 in aprotic solvents.316 Tetramethylammoniumsuperoxide has been ~repared.~le The single and double electron affinities ofthe oxygen molecule have been deduced from the heats of formation andlattice energies of alkali-metal superoxides and peroxides.The covalentbond energy in 022- is negative, (-95 kcal. mole-l), the crystal beingstabilised mainly by the lattice energ~.~17 Rubidium peroxide is completelydissociated318 into the ions Rbf, 022-, in solution in LiN03-KNOs. Theradical ion formulation [(HO),BO-O]-‘ is suggested, to account for theGroup VI.-Oxygen.L. Kolditz, B. Nussbucker, and M. Schrbnherr, 2. anorg. Chem., 1965, 335, 189.D. Hass, 2. unorg. Chem., 1966, 335, 297.SOPA. D. Beveridge and (3. S. Harris, J . Chem. SOC., 1964, 6076.J.Weidlein and I(. Dehnicke, 2. anorg. Chem., 1965, 337, 113.$06 M. H. Khundker and S. S. M. A. Khorasani, 2. unorg. Chem., 1965, 334, 329.a07 D. P. N. Satchell and J. R. Wardell, J . Chem. SOC., 1965, 739.so8D. Ham, 2. amrg, Chem., 1964, 332, 287.809 (a) D. Grdenio and B. Kamenar, Acta Cryat., 1965, 19, 197; (b) D. Rogers ands10 G. A. Olah, J . Amer. Chena. Soc., 1965, 87, 1103.sll N. E. Aubrey and J. R. Van Wazer, J . Inorg. Nuclear Chem., 1965, 27, 1761.s13 K. Dehnicke and J. Weidlein, Chm. Ber., 1965, 98, 1087.813 L. Kolditz and B, Nussbucker, 2. anorg. G?mn., 1965, 337, 191.8I4A. Cyg$nski, Rocznilcd C M . , 1965, 39, 193.81s M. E. Peover and B. S. White, Chem. Comm., 1965, 183; W. Slough, iba., p. 420.*l*A. D. McElroy and J. S. Hashman, I w g .Chem., 1964, 3, 1798.n7L. A. D’Orazio and R. H. Wood, J . Phys. Chem., 1965, 89, 2550, 2658.318 A. Chr6tien and P. Allarnagny, Cmpt en&., 1965, 260, 1425.A. C. Skapski, Proc. Chem. SOC., 1964, 400JOHNSON, PADDOCK AND WARE: THE TYPICAL ELEMENTS 159paramagnetic properties of certain pero~yborates.~l9 The visible spectraof all the oxygen fluorides a t present known, OnF2, (n = 1 4 ) , have beenreported.320Subphur. The S, molecules in monoclinic (#?)-sulphur are crown-shaped,as they are in the rhombic a-m0dification.3~1 So are (a) cyclo-heptasul-phur imide,522a S,KK, which is obtained in high yield in the reduction ofS4N4 or S4N3C1 by hydra~ine;3~2~ (b) cyclohexasulphur 1,3-di-imide, (pro-duced in the same reaction) ;322c and (c) the 1,4-i~omer.~,,~ Cyclopenta-thiotri-imine, S(N,H),, probably the 1,3,5-isorner, has been isolated,323 andNN’-dimethylcyclohexasulphur 1,5-di-imide, S,(NMe) ,, has been preparedfrom S 3Cl and methylamine .324Theproton chemical shifts of the sulphanes H,S,, (x = 1-6), are stronglydependent on chain length.326 Sulphanes react with olefhic compounds oftin, polysulphides such as (Ph,Sn),S,, (x = 3,4), being produced on pyro-l ~ s i s .~ ~ ’ Trithiocarbonates react with CSC1, to give polymeric C-S com-pounds ;328 bromine oxidises trithiocarbonic acid to the polymeric (CS*S z)n.Monothiophosphates M,+PS0,3- are produced either from sodium trithio-carbonate and sodium metaphosphate 32Qa or by alkaline hydrolysis32Qb ofPSCl,. They are oxidised by iod.h~e,~~~c or ferricyanide32Qd todisulphanediphosphonates M4+(P0,S,P0,)4-, from which cyclic thiotri-metaphosphates [containing the (P30,s3)3- ion] are formed by thermaldecomposition.329c The disulphanediphosphonates disproportionate to tri-sulphanediphosphonates in alkaline methanolic sol~tion.~29~ The prefer-ential attack of alkyl halides on the sulphur atoms of PS0,S- is attributed tothe comparative weakness of n-bonding between phosphorus and sulphur.330Umymmetrical disulphides (which disproportionate rapidly) have beenprepared by the displacement of sulphite ion from amino-Bunte ions, e.g.,NH2CH2CH2*SS03-, by rnercaptide~.~~~ The association of amines withelectron-poor disulphides has been studied spectrophotometrically.~32 InStrontium polysulphides (including SrS,) have been*Ip R.Bruce, J. 0. Edwards, D. Gris.com, R. A. Weeks, L. R. Dartee, W. DcEleine,880A. G. Streng and L. Streng, J . Phyg. Chm., 1966, 69, 1079.asrD. E. Sands, J. Amer. Chem. Soc., 1966, 87, 1395.388 (a) J. Weiss and H. S. Neubert, Acta: Cryat., 1965, 18, 815; (b) H. Garcia-Femmdez, C m p t . rend., 1965,260, 1183; (c) W., 261, 745; (d) J. C. Van de Grampeland A. Vos, Rec. Trav. china., 1965, 84, 599.and M. McCmthy, J . Amr. Chern. Soc., 1965, 87, 2057.H. Garcia-Fernandez, Compt. rend., 1965, 260, 6107.324 R. C. Brasted and J. S. Pond, Inorg. Chern., 1965, 4, 1163.a25 H. D. Lutz, 2. anorg. Chem., 1965, 339, 308.326 H. Schmidbaur, M. Schmidt, and W. Siebert, Chern. Ber., 1964, 97, 3374.327 W. T. Schwartz, jun., and H.W. Post, J. 0rganmetaWi.e Ohm., 1964, 2, 425.B. Krebs and G. Gattow, 2. a w g . Chem., 1965, 338, 225; cf. M. Schmidt, “ In-organic Polymers,” ed. F. Gs. A. Stone md W. A. G. Graham, Academio Press, 1962,p. 140.329 ( a ) A. Lamotte, M. Porthault, and J. C. Merlin, Bull. SOC. chim. France, 1965,915; ( b ) F. Feh6r and F. Vial, 2. anorg. Chem., 1965, 335, 113; (c) G. Lsdwig and E.‘Thilo, ibid., p. 126; (d) H. Kern-, I. Z. Steinberg, and E. Katchalski, J . Amer. Chem.Soc., 1965, 87, 3841; cf. Ann. Reports, 1964, 61, 145.380 S. Akerfeldt, Nature, 1965, 206, 505; cf. Ref. 289.s81 33. L. Klayman, J. D. White, and T. R. Sweeney, J. Org. Chm., 1964, 29,3737.**% F. Fischer and R. Gottfd, 2. Chm., 1965, 5, 226160 INORaANIC CHEMISTRYbasic conditions, disulphides are cleaved smoothly by elemental phosphorusto form thiophosphites :333P, + GRSSR -+ 4(RS),P.The boat configuration, which maximises n-interactions between carbonatoms in tetracyanodithiin ma (23a), is skewed in the thiobromide P,S,Br,(23b), so minimising steric repulsions between terminal and ring sulphurat0rns.33~~ The electron spin resonance spectrum of the dibenzothiophenradical ion shows no evidence for the participation of d-orbitals in the bondsto sulph~r.~~5have been prepared from the elements.Iodine reacts with CUBS to giveIBS, which has properties unlike those previously reported for this com-pound.336 The hydrogen dithiocyanate ion has been isolated as its tetra-phenylarsonium salt from the reaction of [Ph4As]+HC12- with KSCN insulphur di0xide.3,~ Caesium thioiodide CsSI has been prepared.338Sulphur dichloride forms 1 : 1 complexes with AlCl,, FeCI,, and SbCl,,which are formuhted as salts of the SC1+ cati0n.33~ The primary reaction inthe thermal decomposition of triarylsulphonium alkoxides 340a appears to bethe formation of the neutral radical Ar3S*, whereas for the halides340b therelative yields of the various RX species are more compatible with theformation of a 4-covalent sulphur intermediate.N-Fluoroformyliminosulphur difluoride SF,:N*COF has been preparedfrom SF, and the isocyanates of silicon, phosphorus and and therelated perfluoroisopropyl compounds RfN:SF*CF(CF,) 2, ( Rf = CF,, C2F5,C,F,), from R,N:SF, and perfluoropropane in the presence of casiumfluoride.342" Further fluorination of the perfluoroalkyl derivatives RfXSF,by N,F4 takes place in ultraviolet light.342b New cations of the typeSeveral ternary compounds in the general class (Cu,Ag) (B,P) (S,Se),,333 Chisung Wu, J .Amer. Chem. SOC., 1965, 87, 2522.384 (a) W. A. Dollase, J . Amer. Chem. SOC., 1965, 87, 979; ( b ) F. W. B. Einstein,336 R. Gerdil and E. A. C. Lucken, J . Amer. Chm. Soc., 1965, 87, 213.336 J. K. Kom, Ann. Ch;m. (France), 1964, 9, 179; cf. E. Wiberg and W. Sturn,337 31. F . A. Dove, Chem. Comm., 1965, 23.33BC. Dagron, Compt. rend., 1965, 260, 1422.3a9 S. N. Nabi and M. A. Khaleque, J . Chem. SOC., 1965, 3626.340 (a) J. W. Knapczyk, G. H. Wiegand, and W. E. McEwen, Tetrahedron Letters,341 A.F. Clifford and C. S. Kobayashi, I w g . Chem., 1965, 4, 571.342 (a) R. D. Dresdner, J. S. Johar, J. Merritt, and C. S. Patterson, Inorg. Chem.,B. R. Penfold, and Q. T. Tapsell, Inm-g. Chem., 1965, 4, 186.2. Naturforsch., 1955, lob, 108.1965, 2971; ( 6 ) G. H. Wiegand and W. E. McEwen, ibid., p. 2639.1965, 4, 678; (b) R. D. Dresdner, 5. Merritt, and J. P. Royal, {bid., p. 1228JOHNSON, PADDOCK AND WARE: THE TYPICAL ELEMENTS 161[R,S:NSR,]+ have been obtained by the reaction of NCI, with thioethersa3"and of sulphoxides with cyanogen halides :u3b2R,SO + *(CNX), -+ [R,S:N:SR,]+X- + C02.The ultraviolet spectrum and diamagnetism of S,N, are explicable only ifmolecular-orbital terms corresponding to S S cross-bonding are included.344Thiotrithiazyl halides S4N3X, (X = C1, Br) have been obtained by theammonolysis of the dihalogenodisulphanes, and other salts by metathesis .345The cation S4N,+ has a planar cyclic structure (24), in which the S-S andN-S lengths correspond to single and approximately double bonds respec-tively.3a6 Monomeric thiazyl fluoride NSF has been prepared 347 by thefluorination of S,N,, and other sulphur-nitrogen compounds by the actionof atomic nitrogen on compounds of bivalent s~lphur.3~~The chemistry of the lower oxides of sulphur has been re~iewed.~49The freezing points of solutions of sulphoxides in sulphuric acid correspondto the formation of the expected R,SOH+, in spite of the deep colours,which are attributed to charge transfer proce~ses.~5*~ Unlike sulphones,N-oxides, or phosphine oxides, sulphoxides exchange oxygen rapidly withsulphuric acid.350* 2-Thiaindane 2-oxide is dimeri~,5~l probably, on theevidence of its proton magnetic spectrum, through a double bridge (25).Dimethyl sulphoxide and alkylsulphinylcarboqlic acids RSO ,CH,CH,*CO,Hare reduced to the sulphides by tervalent phosphorus compounds 352a and byiodide ion.352b Halides of tervalent phosphorus 353a and triphenylphos-phine 353b react with sulphur dioxide to give a mixture of the phosphoryl andthiophosphoryl derivatives; if an excess of sulphur dioxide is used, thethiophosphoryl halides exchange sulphur for ~ x y g e n .~ ~ ~ a Trirnethylphos-phine reacts more vigorously, to give the oxide The crystalstructure of ammonium sulphite monohydrate has been determined ;354 thesulphite ion retains CQV symmetry in (NH,),[Hg(SO,),], and is thereforeco-ordinated through ~ulphur.~5~ Reaction of NF, with molten sulphur343 (a) R.Appel and G. Buchler, AnnaZen, 1965,684,112; (6) P . Y. Blanc, Experientia,344 P. S. Braterman, J . Chem. SOC., 1965, 2297.34ii M. Becke-Goehring and H. P. Latseha, 2. anorg. Chem., 1964, 333, 181.846 J. Weiss, 2. anorg. Chem., 1964, 333, 314; A. W. Cordes, R. F. Kruk, and E. K.847 B. Cohen, T. R. Cooper, D. Hugill, and R. D. Peacock, Nature, 1965, 20'7, 748.348 J. J. Smith and W. L. Jolly, Inorg. Chem., 1965, 4, 1006.349 P. W. Schenk and R. Steudel, Angew. Chem., 1965, 77, 437.350 (a) S. Oae, T. Kitao, and Y. Kitaoka, Bull. Chem. SOC. Japan, 1965, 38, 543;(b) S.Oae, T. Kitao, Y. Kitaoka, and S. Kawamura, ibid., p. 546.351 R. F. Watson and J. F. Eastham, J . Amer. Chem. SOC., 1965, 8'7, 664.354. (a) E. H. Amonoo-Neizer, S. K. Ray, R. A. Shaw, and B. C. Smith, J . Ohem.SOC., 1965, 4296; ( b ) S. Allenmark, Acta Chem. Scand., 1965, 19, 1.353 (a) E. Fluck and H. Binder, Angew. Chem., 1965, 17, 381; (b) B. C. Smith andG. H. Smith, J . Chem. Soc., 1965, 5516.354 L. F. Battell and K. N. Trueblood, Acta Cryst., 1965, 19, 531.1965, 21, 308 (cf. Ann. Reporta, 1964, $1, 145).Gordon, Inorg. Chern., 1965, 4, 681.J. J. Bullock and D. G. Tuck, J . Chem. SOC., 1965, 1877162 INORGANIC CHEMISTRYyields 356 both fhiothionyl fluoride SSF, and NSF; stretching constants havebeen determined 357 for both types of bond in SF,, and the valence problemsof SF, and SF,O considered the~retically.~~BThe main product of the reaction between dilute sulphur trioxide vapourand aqueous ammonia s9 is the nitrilosulphonate (NHaf),[N(SO,)!]3-; the1 : 3 complexes of SO, with oxygen bases are formulated 360 as six-co-or-dinated, e.g., (MeO),S(OH),.The complexes N205,nS03, (n = 2, 3, 4) arepresumably polys~lphates.~~~ Methyl polysulphates MeO(SO,),Me havebeen detected in equilibrium mixtures of sulphur trioxide and dimethyl~ulphate.~6~ Acids of the general formula H[SbF5-,(SO3I?),+,], (n = 0, 1,2,3) have been found in solutions of SbF, and related compounds in fluoro-sulphuric The protonation of weak bases in this solvent has beenstudied by nuclear magnetic resonance spectroscopy,364 and its behaviour asa reaction medium and fluorinating agent has been re~iewed.~6~ A con-venient method for the preparation of amidosulphuryl fluoride NH,SO,Ffrom sulphamide has been described.366a The terminal amido-groups inH,N*S02*NMe*S0,*NH2 and in H2N(S0,*NMe),S0,*NH, react with PCI,to give -N:PCl, derivatives, in which the chlorine atoms can be replaced byphenyl or phenoxy-gr~ups.~~~~ Fluorine reacts with sulphamide in aqueoussolution to form NN-difluorosulphamide NF,*SO,*NH,, which decomposesto NHF, onDisulphuryl fluoride is attacked by anionic nucleophiles thus :S,O,F, + X- ---+ FS0,X + S0,F-,(X = F, C1, N3), and the new compounds FSOa,, CF,SO,N, have beenreported.Disulphuryl chloride oxidises the nucleophile 367 to ClX.Di-(methylsulphuryl) peroxide368a (MeSO2),0, and bis( trifzuoromethylsd-phuryl) peroxide368b have been prepared electrolytically ; the latter compounddecomposes explosively. Tetrafluorohydrazine reacts quantitatively 369 withS2F10:NzFa + --+ 2mzSE’,and N:SF$Et, is obtained in a condensation reaction between thiazyltrifluoride NSF, and diethylamine.8703~ 0. Glemser, U. Biermann, J. Knaak, and A. Haas, Chm. Ber., 1965, 98, 446.~ ~ 5 7 Ed. G, K. Pillai, K. Ramaswamy, and R. Pkhai, Cam&. J . Chem., 1965, 43, 463.358 R. D. Willett, Theor. Chim. Acta, 1964, 2, 393.369 H.P. Lehmann, D. Beyer, and W. Scbeider, 2. amrg. Chem., 1965, 337, 22.3s0R. C. Pad, M. S. Bains, R. Kesh, S. S . Pam, and D. Shgh, Indian J. Ohm.,361B. Vandorpe and J.Heubel, Compt. rend., 1965, 860, 6619.J. R. Van Wazer, D. Grant, and C. H. Dungan, J . Amer. Chem. Soc., 1965, 87,s63 R. C. Thompson, J. Barr, R. J. Gillespie, J. B. Edilne, and R. A. Rothenbury,3a4T. Birchall and R. J. Gillespie, Canad. J . Chm., 1965, 43, 1045,se5A. Engelbrecht, Angew. Chem., 1965, 77, 695.s66 ( a ) L. K. Huber and H. C. Maadell, jun., Irwrg. Chm., 1965, 4, 919; (b) P. Nan-nelli, A. Failli, and T. Moeller, ibid., p. 558; (c) R. A. Wieaboeck and J. K. Ruff, ibid.,p. 123.367 J. K. Ruff, .Tn.org. Chern., 1965, 4, 567.388 (a) R. N. Hasmldine, R. B. Heslop, and J. W. Lethbridge, J . Chm. Soc., 1964,4901; ( b ) R. E. h’oftle and G. H. Cady, Inorg. Chem., 1965, 4, 1010.370 0. Glemser, H. Meyer, and A. Haas, Chern.Ber., 1965, 98, 2049.1965, 3, 239.3333.Inorg. Chm., 1965, 4, 1641.J. L. Boivin, Canad. J. Chem., 1964, 42, 2744JOHNSON, PADDOCK AND WARE: THE TYPICAL ELEMENTS 163Selelzium and Tellurium. Trimethylsilyl selenide (Me,Si),Se is formedfrom Me3SiC1 and PhSeNgBr, and the telluride analogously.lee Improvedmethods for the preparation of (CF,) 2Se,( CP,) 2Se2 (from selenium and silvertrifluoroa~etate)~~1~ and of alkylisoselenocyanates RNCSe (from seleniumand alkyl i s ~ c y a n i d e s ) ~ ~ ~ ~ have been described. Selenocyanates react withorganomercq compounds, e.g.,372Ph,Hg + Se(SeCN), --+ PhHgSeCN + PhSeCN + Se.Selenocarbonates and thioselenocarbonates containing the ions CSe,3-,CSe,S3- and CSeS,3- have been obtained from carbon disulphide or disel-enide.373 Dimethylselenium dihalides Me2SeX, form complexes with bothamines and boron trihalides; the former (X = C1)374a are unstable at roomtemperature, and the latter, (X = ClYBr),374b are salts (Rle,SX)+(BX,)-.The chemistry of the complexes of SeIV, TeIV has been re~iewed.87~ Thedimethylamido-derivatives Me&*SeOCl and (Me,N) ,SeO have been ob-tained from C1,SeO ; the bis( dimethylamido)-compound slowly loses oxygenat room Alkylselknio esters 376b RSe0,R' and the anhy-d~ide~7~c (26) have been prepared.The corresponding(27)acid forms anitrate378c [(CH,)2Se(OH),](N0,),, and selenious acid itself-is basic, forminga perchlorate in which the cation [Se(OH),]+ is pyramidal.376d Potassiumfluoroselenite KSe0,F has been prepared,376e and its properties comparedwith those of KS0,F.Crystalline selenium trioxide exists in stable and unstable forms, in whichthe cyclic tetrameric molecules have the symmetry 8, and D2d respec-t i ~ e l y ; ~ ~ 7 ~ the lengths of the ring bonds alternate in the 8,-modification 377bThe same structure persists in the vapour, in which the tetramer is inequilibrium with monomer units.377c The hydrogen atoms in silver amido-selenate AgSe0,NH , can themselves be substituted by silver ; triammine-diaquotrisilver amidoselenate 378 is formulated asAg(NH3 )SeO3"Ag 12,2=20( a ) H.J. Emeleus and M. J. Dunn, J . Inorg. Nuclear Chem., 1965, 27, 752;373 E. E. Aynsley, N. N. Greenwood, and M. J. Sprague, J . Chem. SOC., 1965, 2395.373 H. Seidel, Naturwisa., 1965, 52, 539.(a) K.J. Wynne and J. W. George, Inorg. Chem., 1965, 4, 256; ( b ) J . A w r .Chem. Soc., 1965, 87, 4750.376 D. I. Ryabchikov and I. I. Nazasenko, Rum. Chem. Rev., 1964, 33, 65.376 (a) R. Paetzold and E. Ronsch, 2. anorg. Chem., 1965, 338, 22; ( b ) ibid., p. 195;(c) R. Paetzold and D. Lienig, ibid., 1965, 335, 289; (d) R. Paetzold and M. Garsoff'ke,ibid., 1965, 336, 52; (e) R. Paetzold and K. Aurich, ibid., 1965, 335, 281.s7' (a) R. Paetzold and H. Amoulong, 2. arz.org. Chem., 1965, 337, 225; (b) F. C.Mijlhoff, Acta Cryst., 1965, 18, 795; (c) F. C. Mijlhoff, Rec. Trccu. chint., 1968, 84, 74.87a I(. DOf3thl and A. Rbzicka, 2. anorg. Chem., 1966, 337, 326.(b) W. J. Franklin and R. L. Werner, Tetrahedron Lettere, 1965, 3003164 INORGANIC CHEMISTRYThe preparation of iodoxyl selenates 379a (IO,),SeO,, IO,HSeO, and thenitrosyl selenates 379b NO-HSeO, and (NO),Se,O, has been described; theSe-O-Se grouping in the diselenate ion is bent.379c The chemical shifts ofa number of compounds relative to 77SeOC1, have been determined.380Bis(bipheny1ene)tellurium (27) has been prepared from TeCI, and 2,2’-dilithi~biphenyl.~~~ A new oxychloride of tellurium, Te6011C1, has beenobtained,382 and a paramagnetic oxide of composition Te,O, has been foundas an intermediate in the thermal decomposition of telluric a ~ i d .3 ~ ~ BariumtelIurate reacts in a more complicated way with fluorosulphuric acid thandoes barium ~elenate,~8~ to give the new pentafluorotellurium( VI) compoundsTeF,OH, TeF,OSO,F, TeF,OSO,H, and (TeF,O),SO,.Nitrous acid and some of its derivatives formstable solvates in hydrogen fluoride, which are useful fluorinating agents.385~So is benzoyl fluoride, (for oxygen-containing compounds of the non-metals),boric oxide being converted by it to boron trifluoride and octamethylcyclo-tetrasiloxane to dimethyldifl~orosilane.~85b The trifluoromethoxides of thelarger alkali metals MOCF,, (M = K, Rb, Cs), have been prepared fromcarbonyl fluoride and a suspension of the metal fluoride in acetonitrile.Theyare immediately hydrolysed by water.386 The effective electronegativitiesof several fluoroalkyl groups have been estimated from the ionisation con-stants of the fluoroalkylmercuric hydroxides RHgOH ;387u the stronginductive withdrawal of electrons by fluoroalkyl groups from the benzenering is partly counteracted by the interaction of the p-electrons of fluorinewith the aromatic n - ~ y s t e m .~ ~ ~ ~ As a consequence of ring strain and thehigh electronegativity of the CF, groups, the carbonyl group in hexafluoro-cyclobutanone is highly polar, and reacts readily with boron halides, silanesand phosphine~.~~~ The addition reactions of hexafluoroacetone (CF,),COwith methyl- and dimethyl-arsine 389* are initiated by nucleophilic attack atcarbon, whereas the adducts with Me,MH, (M = Si,Ge,Sn), are formed byeleetrophilic attack at oxygen.389b The fluoroxy-compounds SF,OF andCF,OF react with N,F, to give the oxydifluoroamines SF,ONF,, CF30NF2.The new compounds are colourless gases which do not react with glass ormercury ., OChlorine and Bromine.Chlorine trifluoride forms 1 : 1 adducts withPF,, BF,, AsF,, and SbF,, in order of increasing stability. They are ionic379 (a) G. Icempe and D. Robus, 2. Chem., 1965, 5 , 394; ( b ) K. Dosthl, A. Rbzifika,and P. Rumigek, 2. anorg. Clzem., 1965, 336, 219; (c) R. Paetzold, H. Amoulong, andA. RSziEka, ibid., p. 278.380 T. Birchall, R. J. Gillespie, and S. L. Vekris, Canad. J . Chem., 1965, 43, 1672.381 D. Hellwinkel and G. Fahrbach, Tetrahedron Letters, 1965, 1823.382 P. Khodadad, Bull. SOC. chiin. France, 1965, 468.383 J. Rosickf, J. Lout, and J. Pavel, 2. anorg. Chem., 1965, 334, 312.384 A. Engelbrecht and F. Sladky, Monatsh., 1965, 96, 159.385 (a) F.Seel, Angew. Chrn., 1965, 77, 689; (b) F. Seel, R. Budenz, and K. Gruner,386 M. E. Redwood and C. J. Willis, Canad. J . Chem., 1965, 43, 1893.887 (a) H. B. Powell and J. J. Lagowski, J . Chem. Soc., 1965, 1392; ( b ) W. A. Shep-388 G. W. Parshall, Inorg. Chem., 1965, 4, 52.389 (a) W. R. Cullen and G. E. Styan, J . OrganmnetuZZk Chem., 1965, 4, 151; (6)390 W. H. Hale, jun., and S . AT. Williamson, Inorg. Chenz., 1965, 4, 1342.Group VII.-FZuurine.Annalen, 1965, 684, 1.pard, J . Amer. Chem. SOC., 1965, 87, 2410.Inorg. Chem., 1965, 4, 1437JOHNSON, PADDOCK AND WARE: THE TYPICAL ELEMENTS 165in the solid and in solution; the ClF,+ ion is bent,3,1a whereas the difluoro-chlorate(1) ion C1P2-, found in the 1 : 1 complex NO+ClF,- of nitrosylfluoride and chlorine monofluoride, is linear.39lb The equilibria of brominewith bromide ions on an anion-exchange resinss2 involve the polybromideions Br3- and Br5-, Lithium bromife LiBrO, has been prepared by thedry reaction between lithium bromide and lithium b r ~ m a t e .~ ~ ~Iodine. The iodine fluorosulphates ISO,F and 13S03F have been pre-pared from iodine and peroxydisulphuryl fluoride S 2O ,F , which is regardedas a pseudo-halogen. The iodine is bound covalently in the solid, but I+and 13+ have been identiiied spectroscopically in solution.394 Iodinedissolves in a solution of iodic acid in sulphuric acid. Measurement ofconductivities and freezing points show that the resulting cation I+ firstdisproportionates to I,+ + IO+; on further addition of iodine, the iodylcation also is reduced to 13+.Similar experiments with IC1 and IBr provideevidence 395 for 12Cl+, I,Br+, and ICI,+. The rapid exchange of iodine iniodide/iodate melt,s Sg6 is attributed to a, reversible redox reaction involvingI I or IIn. The electronic spectrum of the hypoiodite ion has been correlatedwith the photochemical sensitivity of hypohalites.397The hydrogen diiodide ion HI2- has been isolated as its tetra-n-butyl-ammonium ~ a l t ; ~ ~ 8 anion-exchange resins carrying C1-, I-, or SCN- holdiodine strongly 39s as 12C1-, 13-, or 12SCN-. The anion in Bun413 is linear,with equal bond-lengths.4OO Measurements of the temperature coefficientsof conductivity of tetramethylammonium salts containing the 13-, 15-, andI,- ions show that the conductivity is determined mainly by the shortestdistance between polyiodide ions. Polyiodides of the larger 10-methyl-acridinium cation have smaller conductivities, because of the reducedorbital overlap.401Iodine pentoxide reacts with peroxydisulphuryl fluoride to give iodylfluorosulphate in good yield :4021,05 + S20,FF, -+ 2102S0,F + 402.Iodyl fluoride accepts a fluoride ion from KF, to form K+I0,F2-, butgives the hexafluoroarsenate IO,+AsE”,- with arsenic pentafl~oride.~~~The periodate ion dimerises in alkaline solution. The monomer-dimerequilibrium has been measured spectrophotometrically, and the results used391 (a) K.0. Christe and A. E. Pavlath, 2. anorg. Chena., 1965, 335, 210; (a) K. 0.392 H. Irving and P.D. Wilson, J . Inorg. NucJear Chesn., 1964, 26, 2233.393P. Hagenmuller and B. Tanguy, Compt. rend., 1965, 260, 3974.394F. Anbke and G. H. Cady, I w g . Chem., 1965, 4, 269.396 R. A. Garrett, R. J. Giflespie, and J. B. Senior, Inorg. Chem., 1965, 4, 563.3s6 Yu. Ya. Fialkov, V. S. Slonina, and RI. S. ICartavov, Rzcss. J. Inorg. Chem.,397 0. Haimovich and A. Treinin, Nature, 1965, 207, 185.398 K. M. Harmon, S. D. Alderman, K. E. Benker, D. J. Diestler, andP. A. Gebauer,390 C. Barraqu6 and B. Trkmillon, Bull. SOC. ckim. France, 1965, 1674, 1680.400 S. G. W. Ginn and J. L. Wood, Chem. Comm., 1965, 262.401 S. Kawai, R. Kiriyama, M. Uchida, S. Kurabayashi, and H. Milkawa, BUZZ.402F. Aubke, G. H. Cady, and C. H. L. Kennard, Inorg. Chem., 1964, 3, 1799.403 J.J. Pitts, S. Kongpricha, and A. W. Jache, Inorg. Chem., 1965, 4, 257.Christe and J. P. Guertin, Isaorg. Chem., 1965, 4, 905.1964, 9, 116.J . Amer. Chem. Soc., 1965, 87, 1700.Chem. SOC. Japan, 1965, 38, 799; S. Kurabayashi and H. Mikawa, ibid., p. 1410166 INORGANIC CEEMISTRYto calculate a new value of the second dissociation constant of the acid.4wTwo 10, octahedra share an edge 405 in the mesoperiodate anion of thepotassium salt K,[H,12010],8H,0. Further thermogravimetric studies ofthe thermal decomposition of periodates have been reported,408 and aparamagnetic salt BaIO,,H,O obtained, which may contain IyI. Vibra-tional 407 and nuclear magnetic resonance spectra 408a are compatible with thesymmetry Call for IOF,, but the 19F spectra 408a#b give no detailed structuralinformation about the shape of IF,.404 G.J. %&t and J. D. Lewis, Chem. Comm., 1965, 66.405 A. Ferrari, A. Braibauti, and A. Tiripicchio, Acta Cryst., 1966, 19, 629.406 31. Drtitovskf, 2. anorg. Chem., 1964, 334, 169; cf. Ann. Reports, 1964, 61, 147,407 D. F. Smith and 0. M. Begun, J. Chem. Phys., 1965, 43, 2001.408 (a) N. Bartlett, 8. Beaton, L. W. Reeves, and E. J. Wells, C a d . J . Chm.,1964, 4&, 2531; (b) R. J. Gillespie and J. W. Quail, ibid., p. 26713. THE TRANSITION ELEMENTSBy F. E. Mabbs and Q. J. mchh(Chemistry Department, Tits University, Munchester, 13)Fo LL o w IN G previous practices, the advances in transition-metal chemistrywill be reviewed by dividing the elements into groups and then mentioningcompounds generally in order of increasing oxidation state.Papers dealingwith elements from a number of groups will normally only be mentionedonce.All papers dealing with kinetic studies have been omitted; and becauseof lack of space much of the work on solvent extraction and general solutionstudies has had to be omitted. General reviews which have appeared havedealt with transition-metal oxides,l reactions of metal acetylacetonates,2reactions of metal halides with amines and alkyl cyanides, complexes ofsulphur, selenium, and tellurium donors, the Mossbauer effect, polarographicstudies, fused-salt spectrophotometry,4 and magnetic proper tie^.^Scandim and the Lanthanides.-Doubt has been cast on the existenceof lower chlorides of scandium and some new oxides MIScO, (MI = alkalimetal) have been prepared.' A method of preparing high-purity holmiumhas been described,s and vacuum distillation proposed as a means of puri-fying lanthanide chlorides.9 E.s.r.studies lo of europium dissolved in liquidammonia suggest that the species present are EuII and solvated electrons.The crystal structures11 of the oxide hydroxides (MOOH) of holmium-,erbium-, and ytterbium-( m) are based on a trigonal prismatic co-ordination.Phase studies12 of the Gd-GdC1, system led to the isolation of GdC1,.,while the corresponding iodide system yields a metallic, ferromagneticphase GdIpo4.The co-ordination chemistry of the lanthanides has been reviewed ;13the possibility of fhding laser materials seems to be stimulating interest inthis field.A co-ordination number of ten has been established14 for thecompound La(H,O), (edta),SH,O and a number of eight-co-ordinate tropo-Bull. SOC. c h h . Prance, 1965, 1051-1215.J. P. Coleman, Angew. Chem. Internat. Edn., 1965, 4, 132.G. W. A. Fowles, Progr. Inorg. Chem., 1964, 6, 1.J. F. Duncan and R. M. Golding, Quart. Rev., 1965, 19, 36; D. R. Crow and3. V. Westwood, ibid., p. 57; R. A. Walton, ibid., p. 126; D. M. Gruen, ibid., p. 349;S. E. Livingstone, ibid., p. 386.B. N. Fig& and J. Lewis, Progr. Inorg. Chem., 1964, 6, 37.13 J. D. Corbett and B. N. Ramsey, Inorg. Clzern., 1965, 4, 260.7 R. Hoppe, B. Schapers, H.-J. Rohrborn, and E. Vielhaber, 2. anorg. Chem.* K. T. Faler, J . Imrg. Nuclear Chem., 1966, 27, 25.* G. SchBmacher, Compt. rend., 1965, 260,182.1965, 339, 130.lo M. J. Blandamer, L. Shields, and M. C. R. Symons, J . Chem. SOC., 1965, 3759.I1A. N. Christensen, Acta Chern. Scad., 1965, 19, 1391.la J. E. Mee and J. D. Corbett, Inorg. Chem., 1965, 4, 88.l3 T. Hoeller, D. F. Ifartin, L. C. Thompson, R. Ferrtk, C;. R. Feistel, and W. J.14M. D. Lind, B. Lee, and J. L. Hoard, J . Amer. Chern. Soc., 1965, 87, 1611.Randall, Chm. Rev., 1965, 65, 1168 INORGANIC CHEMISTRYlone, propanedione, and 4-picoline N-oxide complexes are kn0wn.15 It isoften possible to prepare both six- and eight-co-ordinate complexes with@-diketone ligands.l6 Complexes with 1 ,lo-phenanthroline, act’-bipyridyldimethylacetamide, and salicylaldehyde have been described .17A preparation of cerium(rv) fluoride has been described.lsThe Actinides.-Element 104 has been reportiedl9 but no details are ayet available; presumably this the first member of the fourth transitionseries. Potential methods for preparing new elements have been reviewed.20The separation of americium, curium, berkelium, and californium ;21 and ofprotactinium from monazite sand has been described.22Small traces of tungsten, from the electrodes used in arc-melting uraniumdicarbide, have been shown markedly to affect 23 the nature of the hydrolysisproducts of the carbide; and this may affect the results published by otherworkers 24 on uranium and thorium carbides. Plutonium borides have beenidentified 25 up to PuB12.Many ternary oxides of these elements have beencharacterised.26 Attempts to repeat the preparation of UN, have alwaysyielded 27 UN,.,.A number of halide complexes have been described, e.g., thorium( m)iodide and 01- and /%forms of the di-iodide;28 Cs3PuCI,,2€€,0 is known 29 andcompounds R1,MI, (MIv = Th or U) have also been prepared.30 Uraniumpentafluoride has been characterised and a semi-continuous preparationde~cribed.~~ Single crystals of alkali-metal salts MUF, have been prepared.32Potassium heptafluoroprotactinate(v) is nine-co-ordinated 33 while lithiumoc t a,fluoropr ot a ct ina t e ( v ) is presumably eight - co- ordinat ed , 34 Thoriumoxyiodide has been prepared from Tho, and ThI,, and is said 35 not to be al6 E.L. Meutterties and C. M.Wright, J . Amer. Chem. Soc., 1966,87,4706; J. Blancand D. L. Ross, J . Chem. Phys., 1965, 43, 1286; N. J. Rose and E. Abramson, ibid.,1965, 42, 1849.16 L. R. Melby, N. J. Rose, E. Abramson, and J. C. Caris, J . Amer. Chem. SOC.,1964,86, 5117; H. Bauer, J. Blanc, and D. L. Ross, ibid., p. 6125; S . M. Lee and L. J.Nugent, J. Inorg. Nuclear Chem., 1964, 26, 2304.1’ F. A. Hart and F. P. Laming, J . Inorg. Nuclear Chem., 1965, 27, 1605, 1826;T. woeller and G. Vincentini, ibid., p. 1477; R. G. Charles, ibid., 1964, 26, 2298.i* W. J. Asher and A. W. Wylie, Austral. J. Chem., 1965, 18, 959.19 Nuclear Science Abstracts, 1965, 19, Abstract no. 3233.20 C. Keller, Angew. Chem. Internat. Edn., 1965, 4, 903.21 J. Kooi, R. Boden, and J. Wijtra, J. Inorg.Nuclear Chem., 1964, 26, 2300.22 T. N. V. Pillai, J. Indian Chem. SOC., 1965, 42, 32.23 33. J. Bradley and L. M. Ferns, Inorg. Chem., 1965, 4, 597.Z 4 See e.g., L. M. Ferris and M. J. Bradley, J . Amer. Chem. SOC., 1965, 87, 1710;M. J. Bradley, M. D. Pattengill, and L. M. Ferris, Inorg. Chem., 1965,4,1080; S . Evered,M. J. Moreton-Smith, and R. G. Sowden, J. Inorg. Nuclear Chem., 1965, 27, 1867;J. Besson, P. Blum, and B. del Litto, Compt. r e d . , 1965, 261, 1859.25 H. A. Eick, Inorg. Chem., 1965, 4, 1237.26 C. Keller, L. Koch, and K. H. Walter, J . Inorg. Nuclear Chem., 1965,27,1205-53.27 C. E. Price and I. H. Warren, Inorg. Chem., 1965, 4, 115.28 D. E. Scaife and A. W. Wylie, J. Chem. SOC., 1964, 6450.2 9 R . E. Stevens, J. Irtorg. Nuclear Chem., 1965, 27, 1873.30 K.W. Bagnall, D. Brown, P. J. Jones, and J. G. H. du Preez, J. Chem. SOC.,3lA. S. Wolf, J. C. Posey, and K. E. Rapp, Inorg. Chem., 1965, 4, 751.32 G. D. Sturgeon, R. A. Penneman, F. H. Kruse, and L. B. Asprey, Inorg. Chem.,33 D. Brown and A. J. Smith, Chem. Corm., 1965, 554.a 4 D. Brown and J. E. Easey, Nature, 1965, 205, 589.3 5 D . E. Scaife, A. G. Turnbull, and A. W. Wylie, J. Chem. Soc., 1965, 1432.1965, 350.1965, 4, 748MABBS AKD MACHIN: THE TRANSITION ELEMENTS 169'' thoryl " compound. A number of thiocyanate complexes of uranium(rv)and thorium(m) with up to eight ions co-ordinated have been rep~rted.~eTricyclopentadienyl complexes of uranium, thorium, and plutonium arerep~rted.~' Among other complexes described are : uranium(rv) tetracar-b ~ x y l a t e s , ~ ~ amide complexes of uranium(m) and thorium(m) iodides 39 ando-phenanthroline and triphenylphosphine complexes of thorium( IV) chl0ride.4~An unusually large shift in the P=O stretching frequency has been noted 41in the complexes UCl,R,PO (R = Ph or C8H1,).Titanium, Zirconium, and Hahiuxn.-The monoxides of these elementshave been studied by heating the dioxide to above 2500" and quenching inan argon or neon matrix.42 A preparation for zirconium(n) chloride has beendescribed.43 Attempts 44 to repeat the preparation of dicyclopentadienyl-titanium led to the product (C5H,),TiC1.Zirconium(m) fluoride has been prepared45 from the hydride and anH,-HF mixture ; the product is ferromagnetic.The binuclear cyclopenta-ciiene complex [ (C,H5)zTiC1], has magnetic properties similar to those ofcopper(=) acetate 46 and its structure is discussed on this basis.Complexesof p-diketones with titanium-(In) and -(Iv) and zirconium(II1) have beencharacterised fully.47 Adducts of titanium(=) chloride with a wide rangeof ligands continue to attract attention 48 and similar work on vanadium andmolybdenum compounds has been reported. The complex TiCl,( bipyridyl)has been shown 49 to be an electrolyte [TiCl,(bipyridyl),]Cl.Many anhydrous metal chlorides may be obtained5* by treating theoxide with boiling octachlorocyclopentene. In some cases (e.g., MoV1 andWvl oxides) an oxychloride is formed. Chlorine azide has been shown 51 toreact with TiC1, and VOCI, yielding TiCl,N, and VOCl,N, which decomposeto the nitrides TiClN and VON.Hexanitrato-complexes of zirconium- andV. I. Belova, Ya. K. Syrkin, and E. N. Traggeim, Russ. J . Inorg. Chem., 1964,9, 1551; A. K. Molodkin and G. A. Skotnikova, ibid., p. 32.37 F. Baumgartner, E. 0. Fischer, B. Kanellakopulos, and P. Laubereau, Angew.Chem. Internat. Edn., 1965,4, 878; G. L. Ter Haar and iST. Dubeck, Inorg. Chem., 1964,3, 1648.38 R. C. Paul, J. S. Ghota, and M. S. Bains, J . Inorg. Nuclear Chem., 1965, 27,265.39 K. W. Begnall, D. Brown, P. J. Jones, and J. G. H. du Preez, J . Chem. Soc.,1965, 3594.40 B. W. Fitzsimmons, P. Gans, B. C. Smith, and M. A. Wasseff, Chem. and Id.,1965, 1698.K. W. Bagnall, D. Brown, and J. G. H. du Preez, J . Chem.SOC., 1965, 5217.4 2 W. Weltner and D. McLeod, J . Phys. Chem., 1965, 69, 3488.4 3 B. Swaroop and S. N. Flengas, Canad. J . Chem., 1965, 43, 2115.G. W. Watt and L. J. Baye, J . Irwrg. Nuclear Chem., 1964, 26, 2099.45 P. Ehrlich and G. Kaupa, 2. anorg. Chem., 1964, 333, 209.46 R. L. Martin and G. Winter, J . Chern. SOC., 1965, 4709.4 7 M. Cox, J. Lewis, and R. S. Nyholm, J . Chem. SOC., 1964, 6113; 1965,2840.48 G. W. A. Fowles and R. A. Walton, J . Chem. SOC., 1964, 4953; G. W. A. Fow~~s,R. A. Moodless, and R. A. Walton, J . Inorg. Nuclear Chem., 1965,27,391; D. A. Edwards,G. W. A. Fowles, and R. A. Walton, ibid., p. 1999.4 9 M. T. Siddiqui, N. Ahmad, and S. M. F. Rahman, 2. anorg. Chem., 1965, 336,110.A. B. Bardamil, F. N. Collier, and S.Y. Tyree, J . Less Common Metals, 1965,9, 20.s1 K. Dehnicke, J . Inorg. Nuclear Chem., 1965, 27, 809170 INORGANIC CHEMISTRYhafnium(1v) have been prepared 52 and a wide range of peroxy-complexesof early transition-group elements characterised.53Eight- co-ordinate complexes of zirconium- and hafnium-(rv) and niobium-and tantalum-(v) with tropolone have been ~tudied,~4 but o-phenylenebis-diethylarsine only forms sis-co-ordinate complexes with titanium(rv)chloride or bromide and vanadium(Iv) chloride, unlike the correspondingbi~dimethylarsine.~~ NN'-Dialkyldithiocarbamate complexes M( S ,CNR,),,[M = Ti, Zr, HfIY] and M(S,CNR,)5, [M = V, Nb, TaV] can be prepared 56from the corresponding complex &l(NR,), in carbon disulphide solution. Itis suggested that the titanium and zirconium compounds are eight-co-ordinate. The oxidation of titanium, vanadium, or chromium metal byhalogens in acetonitrile solution leads 57 to a variety of products dependingon the halogen used.As with titanium(m), solvent adducts of titanium(rv)continue to receive attention,58 a wide variety of donors being employed.The compound (Me,N),(TiCl,O) has been prepared, and is said59 to befive-co-ordinate. Dicyclopentadienyltitanium dichloride reacts 60 withammonia or methylamine at -37" breaking only one Ti-C1 bond but a troom temperature, the Ti-C,H, bonds are broken.Vanadium, Niobium, and TantaIum.-The chemistry of oxovanadium(rv)has been reviewed, and so have vanadium-oxygen systems.61 Very littlework on vanadium(@ systems has been reported.Acetylacetone and pico-linic acid complexes have been studied in solution G2 and a series of bivalentmetal tetrachloroaluminates [M( MU,) 2] prepared for all first-row transitionelements except titanium.63 The e.8.r. spectrum of vanadiurn(n) in a cad-mium chloride lattice has been studied.64Studies of metal clusters have been extended to niobium and tantalumhalides: compounds M&,, have been prepared for M = Nb or Ta andX = C1, Br, or I; usually by reduction of the pentahalide with a metal in ittemperature-gradient. The crystal structures of ??b6C1,, and Ta61,, arebased on octahedral arrays of metal atoms. 65 Similar preparative procedures6 1 K. W. Bagnall, D. Brown, and J. G. H. du Preez, J. Chem. SOC., 196415523.53 W.P. Griffith, J. Chem. SOC., 1964, 5248.54 E. L. Muetterties and C. M. Wright, J. Amer. Chem. Soc., 1965, 87, 4706.55 R. J. H. ClBrk, J . Chem. Soc., 1965, 5699.56 D. C. Bradley and M. H. Gitlitz, Chem. Comm., 1965, 289.67 B. J. Hathaway and D. G. Holah, J. Chem. SOC., 1965, 537.68 K. Baker and G. W. A. Fowles, J . Less Common Metah, 1965,8,47; V. Krishnanand C. C. Patel, J . Inorg. Nuclear Chem., 1964, 26, 2201; A. D. Westland and L. West-land, Canad. J . Chem., 1965, 43, 426; D. I. Tsekhovol'skaya, Russ. J . Inorg. Chem.,1964, 9, 755.6a A. Feltz, 2. anorg. Chem., 1965, 838, 147.6o A. Anamostopoulos and D. Nicholls, J. Inorg. Nuclear Chem., 1965, 27, -339.8, 1.61 J. Selbin, Chem. Rev., 1965, 65, 163; J. Stringer, J .Less Common Metals, 1965,6% W. I?. Sohaefer, I w g . Chem., 1965, 4, 642; R. C. Mercier, M. Bonnet, and M. R.63 R. F. Belt and H. Scott, Inorg. Chem., 1964, 3, 1785.64 I. Y. Chm, D. C. Doetschman, C. A. Hutchison, B. E. Kohler, and J. W. Stout,J . Chem. Php., 1965, 42, 1048.66 A. Simon, H. G. Schnering, H. Wohrle, and H. Schafer, 2. anorg. Chem., 1966,339, 165; D. Bauer, H. G. Schnering, and H. Schiifer, J . Less Common Metals, 1966,8, 388; R. J. Allen and J. C. Sheldon, AecstraE. J . Chem., 1965, 18, 277.Pgris, Bull. SOC. chirn. Fvame, 1965, 2926; Compt. rend., 1965, 260, 3092MABBS AND MACHIN: THE TRANSITION ELEMENTS 171have resulted g6 in the isolation of Nb6F15, Ta,XI6 (X = C1 or Br), andTa,Br,,. It has been shown 67 that these M6C1122+ systems readily undergoa two-electron oxidation, and their spectra have been interpreted.68Potassium hexafluorovanadate( m) may be prepared from vanadiummetal and KHF, and purified by sublimati~n.~~ Vanadium- and cluomium-(m) chlorides have been shown to act as chloride donors to e.g., SbCl,,SnC1, ; the hexachloro-species being formed.Trisdithioglyoxal complexes ofvanadium, molybdenum, tungsten, and rhenium(m) have been prepared 71and may have a triganal prismatic co-ordination [see under rhenium(m)].Tantalum(m) chloride forms M,TaCl, in alkali-metal halide melts,72 but theco-ordination number is not discussed.Vanadium(rv) chloro-complexes M,IVCl, can be prepared 73 from thecorresponding [VOC1,]2- salt in thionyl chloride. The same species may beprepared from VC1, in liquid HCl.In complexes of the types [VS,C,R6]Z,(R = CF3, x = 2- or I - ; R = Ph, x = 2-, 1-, or 0) and [V(S,C,H,X),]2-(X = H or Me,), the unpaired electron has been shown 74 to be predominantlyin ligand orbitals for all species with x = 2 (and z = 0 when R = Ph); itis thus not surprising that these complexes oxidise readily. A number ofsix-co-ordinate adducts of vanadium( IV) chloride have been prepared, 75however, some sulphur, phosphorus, and arsenic ligands lead to reduction tovanadium( m) . Some polymeric nitrosyl complexes [V(NO) 3C12]n have beenprepared.76 A number of vanadyl(Iv) species have been studied. Thecomplex VOL (L = quadridentate /3-keto-imine) has been partially re-solved. 7 7 A new method of synthesising maleonitriledithiolate complexeshas been devised 78 in which sodium dithiocyanoformate is reacted withvanadyl sulphate.Thermodynamic studies of ligand addition to the sixthco-ordination site of VO(acetylacetone), reveal 79 a wide range of equilibriumconstants. E.s.r. measurements on vanadyl phthalocyanine confirm 80that the unpaired electron is in a 3d, orbital. Niobium(rv) fluoride andiodide and tantalum(rv) chloride and bromide have been prepared;81 NbF,saH. Schizfer, H. G. Schnering, H.-J. Niehues, and H. G. Nieder-Vahrenholz,J . Less Comrnon Metals, 1965, 9, 95; P. J. Kuhn and R. E. McCarley, Inorg. Chem.,1965, 4, 1482; R. E. MoCarley and J. C. Boatman, ibid., p. 1486; EI. ScMfer, R. Gerken,and H. Scholx, 2. anorg. Chem., 1965, 335, 96.67 R.E. McCarley, B. G. Hughes, F. A. Cotton, and R. Zimmerman, Inorg. Chem.,1965, 4, 1491.68M. B. Robin and N. A. Kuebler, Jnorg. Chem., 1965, 4, 978.69 B. M. Wanklyn, J . Inorg. Nuclear Chem., 1965, 27, 481.70V. Gutrann, G. Hampel, and W. Lux, Mon&h., 1965, 96, 533.71 G. N. Schrauzer, V. P. Mayweg, and W. Heinrich,Chem.and Ind., 1965, 1464.m V. V. Safanov, €3. C. Korshunov, Z . N. Shevatova, and S. I. Bakum, Rum.13P. A. Kilty and D. Nicholls, J . Chem. Soc., 1965, 4915.A. Davison, N. Edelshin, R. H. Holm, and A. H. Maki, Inorg. Ohm., 1965,4,55.76 B. E. Bridgland, G. W. A. Fowles, and R. A. Walton, J. Incwg. Nuclear Ohm.,l6 W. Beck, K. Lottes, and K. Schmidtner, Angew. Chem. Internat. Edn., 1965,7 7 K. Ramaiah and D. I?.Martin, J. Inorg. Nucbar Ohm., 1965, 27, 1663. '* N. M. Atherton, J. Locke, and J. A. McCleverty, Chem. and Id., 1965, 1300.R. L. Carlin and F. A. Walker, J . Amer. Chem. SOC., 1965, 87, 2128.O0 J. M. ASSOUP, J. Goldmacher, and S. E. Harrison, J . Chem. Phys., 1965, 43, 169.F. P. Gortsema and R. Didchenko, Inorg. Chem., 1965, 4, 182; P. W. Seabaughand J. D. Corbett, ibid., p. 176; V. V. Sofonov, B. G. Korshunov, Z. N. Shevstova, andJ. Inorg. Ohm., 1964, 9, 914.1965, 27, 383.4, 161172 INORGANIC CHEMISTRYdisproportionates a t 350" in VMUO yielding NbF, and NbF,; however NbI,melts incongruently at 503" forming Nb,I,.Studies of niobium(v) and tantalum(v) halides have been continued.NbCl, or TaCl, will abstract an oxygen atom from triphenyl-phosphine or-arsine oxide yielding 82 the oxytrichloride, and Ph,Cl,P or Ph,Cl,As.Ithas been estimated that niobium(v) and tantalum(v) fluorides are less thanone per cent ionised in the molten state and shown that niobium(v) chlorideremains a dimer in dry, oxygen-free carbon tetrachloride or nitromethanebut that in acetonitrile a monomer NbCl,CH,CN is formed.83 A number ofaddition compounds of the pentahalides have been isolated. 84 The structuresof some fluoro-peroxy-complexes of niobium, tantalum, molybdenum, andtungsten have been deduced from lgF.n.m.r. studies.85 The reaction ofo-phenylenebisdimethylarsine (diars) with niobium(v) or tantalum(v) chlorideor bromide in a non-hydroxyllic solvent yields seven-co-ordinate speciesMX,(diars), but if an excess of diarsine is heated in a sealed tube withNbX,, NbX,, or NbOX, (X = C1, Br, or I) an eight-co-ordinate speciesNbX,(diars) 2, isomorphous with TiCl ,(diars), results.86Chromium, Molybdenum, and Tungsten.-Apart from the carboiiyl de-rivatives dealt with elsewhere, a number of zero-valent compounds have beenprepared.Nitrosyl chloride reacts 87 with molybdenum and tungstenhexacarbonyls yielding the dinitrosyl dichloro-complex. These readily formcomplexes M(NO),C12L, with amines and phosphines. Phosphorus tri-fluoride reacts 88 with tungsten hexachloride to form the complex W(PF,),but CoI, only yields HCo( PF,),. A maleonitriledithiolate (MNT) complexPh,P[Mo(NO),(MNT),] has been reported,sg and the constrained phosphiteester, 4-methyl-2,6,7-trioxa-l-phosphabicyclo[2,2,2, ]octane has been shown 90to form mono- and di-substituted complexes with chromium, molybdenum,tungsten, iron, and nickel carbonyls.It has been reported that phosphoro-benzene [(PhP),] undergoes ring expansion to the pentamer when reactedwith molybdenum or tungsten carbonyl yielding (PhP) 5(Mo,W)(CO) 5 , how-ever, this has been disputed by other workers.91 Electron-diffractionstudies 92 of dibenzenechromium show that the complex has DGh symmetryand that C-C bond lengths do not differ by more than 0.02 8.L. G. Shadrova, Russ. J . Inorg. Chem., 1965, 10, 359; S. S. Berdonosov and A. V.Lapitskii, ibid., p. 152.82 D. B. Copley, F. Fairbrother, and A. Thompson, J . Less Common Metals, 1065,8, 2567.83 F. Fairbrother, K.H. Grundy, and A. Thompson, J . Chem. SOC., 1965, 761;D. L. Keppert, and R. S. Nyholm, ibid., 2871.84 F. Fairbrother, K. H. Grundy, and A. Thompson, J . Chem. SOC., 1965, 765;K. Feenan and G. W. A. Fowles, ibid., p. 2449; J. Desnoyers and R. Rivest, Cunad. J .Chem., 1965, 43, 1879.85 D. F. Evans, W. P. Griffith, and L. Pratt, J . Chem. SOC., 1965, 2182; J . E.Guerchais, B. Spinner, and R. Rohmer, Bull. SOC. chim. France, 1965, 55.86 R. J. H. Clark, D. L. Keppert, andR. S. Nyholm, J . Chem. SOC., 1965, 2865, 2877.8 7 F. A. Cotton and €3. F. G. Johnson, Inorg. Chern., 1964, 3, 1609.88 Th. Kruck, W. Lang, and A. Engelmann, Angew. Chem. Internat. Edn., 1965,4,148.8s J. Locke and J. A. McCleverty, Chem. Comm., 1965, 102.90 J. G. Verkade, R.E. McCarley, D. G. Hendricker, and R. W. King, Inorg.91 H. G. Ang. J. S. Shannon, and B. 0. West, Chem. Comm., 1965, 11; C. W. A.9 2 A. Haaland, Acta Chern. Scand., 1965, 19, 41.Chem., 1965, 4, 228.Fowles and D. K. Jenkins, ibid., p. 61MABBS AND MACHIN: THE TRANSITION ELEMENTS 173The wetting of chromium, molybdenum, and tungsten by molten sodiumhas been studied.93 The reaction of molten sodium with molybdenum(rv) ortungsten(1v) oxide fields the metal, or an oxide Na,(Mo,W),06 dependingon temperature, while Cr03 yields the chromium(rv) compound Na,Cr0,.94Chromium(n) compounds are receiving greater attention this year. Inthe alkali-metal halide-chromium(r1) chloride systems both MICrCl, andM2CrC1, can be prepared when MI is Cs, Rb, or K, but when M = Na onlyNa,CrCl, is said to exi~t.~5 Na,CrF, has been prepared and shown 96 to beair-stable but NaCrF, could not be obtained.Mass-spectrometric studies 97have shown that the monofluoride CrF is formed when CrF, and chromiummetal are heated together. A number of chromium(n) complexes, mainlywith nitrogen donors, have been prepared 98 and magnetic and spectralstudies g9 of these, and other complexes have been reported. The magneticproperties of a number of phthalocyanine complexes have been investi-gated.loO The structure of molybdenum(n) acetate, which was discussed inlast year's report, has now been elucidated:lol it is a dimer, similar tocopper(I1) acetate but with an exceptionally short Mo-Mo distance of2-11 A (cf. expected value of about 2.9 A).The low-frequency infrared spectra of many complexes of the transitionelements have been assigned.lo2 The ion [Mo,C1,I4+ forms lo3 addition com-pounds with many ligands, e.g., [Mo&1&6]4+, [Mo,Cl,,L,] etc.The speciesK6M03C1,,, (NH,),Mo3Cl1,,H,O and cs6MO&11, have also been prepared.lwIn the MCl-CrC1, systerns,lO5 both M3CrC16 and M3Cr2C19 species areformed when M = Rb or Cs, but only the monomer exists when M = Li, Na,or K. The magnetic properties of molybdenum(II1) chloride have been inter-preted106 on a trimeric model. The ligand-field parameter, Dp, for thenitrogen end of cyanide ligands has been estimatedlo7 to lie between 950and 1010 cm.--l from studies of KFeCr(CN), and KCrFe(CN),: it is suggestedthat the former contains the unit FeII-NrC-CrIII.The compound pre-viously formulated as Cr3(MeC02),(OH),C1,8H,0 has been shown lo* to beCr,(MeCO ,) ,0.C1,5H20.83 C. C. Addison and E. Iberson, J . Chem. SOC., 1965, 1437.s4 C. C. Addison, M. G. Barker, and R. J. Pulham, J . Chem. SOC., 1965, 4483;95 H.-J. Seifert and K. Klatyk, 2. anorg. Chem., 1964, 334, 113.D6 A. J. Deyrup, Inorg. Chem., 1964, 3, 1645.O 7 R. A. Kent and J. L. Margrave, J. Amer. Chem. SOC., 1965, 87, 3582.D8 R. L. Pecsok, R. A. Garber, and L. D. Shields, Inorg. Chem., 1965, 4, 447; D. G.Holah and J. P. Fackler, ibid., p. 1112.g e A. Earnshaw, L. F. Larkworthy, and K. S. Patel, Chem. and Ind., 1965, 1521;J . Chem. SOC., 1965, 3267; 2. a w g . Chem., 1964, 334, 163; J. P. Fackler and D.G.Holah, Inorg. Chem., 1965, 4, 954.C. C. Addison and M. G. Barker, &id., p. 5534.looA. B. P. Lever, J. Chem. SOC., 1965, 1821.lolD. Lawton and R. Mason, J. Amer. Chem. SOC., 1965, 87, 921.lo2 J. Lewis, R. S. Nyholm, and G. A. Rodley, J . Chem. SOC., 1965, 1483; R. J. H.Clark and C. S. Williams, Imrg. Chem., 1966, 4, 350.lo3 F. A. Cotton and N. F. Curtis, Inorg. Chem., 1965, 4, 241.lo4 I. R. Anderson and J. C. Sheldon, AustraE. J. Chem., 1965, 18, 271.lob I. V. Vasil'kova, A. I. Efimov, and B. 2. Pitirimov, Russ. J. Inorg. Chem.,lo* R. Colton and R. L. Martin, Nature, 1965, 207, 141.lo7 D. F. Shiver, S. A. Shiver, and S. E. Anderson, Imrg. Chem., 1965, 4, 725.lo8 B. N. Figgis and G. B. Robertson, Nature, 1965, 205, 694.1964, 9, 493174 INORGANIC CHEMISTRYComplexes of amines and amine oxides 109 with first-row transition ele-ments have been described.It has been suggested 110 that a perchlorate ionis co-ordinated in solutions of chromium(m) ions in 12~-HC10,. The mag-netic properties of a range of polynuclear chromium(m) complexes havebeen reported.lll Unlike some other trihalides, molybdenum(m) halidesreact with urea and thiourea to form complexes MX,L, rather than the[MLJ3+ species.l12 Sulphur-bridged polymers may be prepared by reactionof Li,MoCl, with chelating sulphur ligends.l13Adducts of the type MoCl,L, are readily prepared 114 from molybdenum-(IV) chloride. The photolysis of the [Mo(CN)J4- ion in aqueous solutionyields HsM~(CN)4(OH),,H,0 as the final product, not K,Mo(CN)~(OH), aspreviously reported.l15 At high temperature, molecular hydrogen reduce8K,Mo(CN), to a molybdenum(n) species K4Mo(CN) 6.Extraction of thisproduct with methanol, in air, yields K,Mo(CN),. The tungsten analoguebehaves similarly.l16 New methods for preparing molybdenum and tungstenoxyhalides, and addition reactions of these compounds have been des-cribed .llNew molybdenum and tungsten bronzes have been described.ll* Amethod for growing single crystals of salts of heteropoly-acids has beendevised 119 and applied to ammonium 12-molybdophosphate. The reductionof molybdic acid with diphenylcarbazide has been studied;120 dimericspecies are produced. Several polytwgstate systems have been studied.121Manganese, Technetium, and Rhenium.-The chemistry of technetiumand rhenium; and the analytical chemistry of technetium have been re-viewed.lZ2A five-co-ordinate structure has been established 123 for the compounds(Ph2MeAs0),M(C1O,),; [MI1 = Mn+Zn]; the fifth position in a tetragonallo@ J.H. Bright, R. S. Drago, D. M. Hart, and S. K. Madan, Inorg. Chem., 1965,4,18 ; R. Longhi and R. S. Drago, ibid., p. 11 ; R. S. Drago, J. T. Donoghue, and D. W.Herlocker, &id., p. 836; S. K. Madan and W. E. Bull, J . Inmg. Nuclear Chem., 1964,26, 2211.1l0 K. M. Jones and J. Bjerrum, Acta Chem. Scund., 1965, 19, 974.111T. Morishita, K. Hori, E. Kyuno, and R. Tsuchiya, Bull. Chem. Soc. Japan,1965, 38, 1276; H. Kobayashi, T. Haseda, and M. Mori, ibid., p. 1455.112 T. Komorita, S.Miki, and S. Yamada, Bull. Chem. SOC. Japan, 1965, 38, 123;V. I. Spitsyn, I. D. Kolli, and T’am Wen-hsai, Rws. J. Inorg. Chem., 1964, 9, 51; A. I.Grigor’ev, T’am Wen-hsai, I. D. Kolli, and V. I. Spitsyn, ibid., p. 1397.113 L. F. Lindry, S. E. Livingstone, and T. N. Lockyer, Austral. J. Chem., 1966,18, 1549.1l4 E. A. Allen, K. Feenan, and G. W. A. Fowles, J. Chem. Soc., 1965, 1636.llaA. W. Adamson and J. R. Perumareddi, Inorg. Chem., 1965, 4, 247.116 J. S. Yoo, E. Griswold, and J. meinberg, Inorg. Cheem., 1965, 4, 365.117 R. Colton and I. B. Tomkins, Austral. J . Chem., 1965, 18, 447; K. Feenan andG. W. A. Fowles, Inorg. Chem., 1965, 4, 310; D. A. Edwards, J . Inorg. Nwlear Chem.,1965, 27, 303.P.-H. Hubert, Compt. rend., 1965, 260, 3677; L.E. Conroy and T. Yokokawa,Inorg. Chem., 1965, 4, 994.ll0 J. van R. Smit, J. Inorg. Nuclear Chem., 1966, 27, 227.lao A. Paigankar and B. C. Haldar, J. Indian Chem. Soc., 1965, 42, 25.H. R. Craig and S. Y. Tyree, Inorg. Chem., 1965, 4, 997; W. N. Lipscomb, ibid.,p. 132; 0. Glemser, W. Holzangel, W. Holtje, and E. SchwarzIIltLM, 2. Nuturforah.,1965, 20b, 725.la2 R. Colton, “ The Chemistry of Rhenium and Technetium,” J. Wiley, New York,1965; A. A. Pozdnyakov, Russ. Chem. Rev., 1965, 84, 129.13* J. Lewis, R. S. Nyholm, and G. A. Rodley, Nature, 1965, 207, 72MABBS AND MACHIN: THE TRANSITION ELEMENTS 175pyramidal arrangement being occupied by a perchlorate group. DimericN-methylsalicylaldimine complexes of manganese-, cobalt-, and zinc-(n)have also been shown to be five-co-ordinate.124 The nitrate ligands aresaid 125 to be bidentatre in complexes [M(C,H,NO),(NO,),]; MI1 = Mn, Co,Ni, or Cu; this is supported by infrared and visible spectroscopic evidence.The infrared spectra of complexes [M(NC0)J2-; MI1 = Mn-+Zn can beassigned by assuming Td symmetry (except for M = Cu), implying a linearM-N-C-0 system; ions M(NCS)42-, MI1 = Mn or Fe are said to be tetrahe-dral and nitrogen-bonded.126 The ligand-field strength of 4,4',4",4"' -tetrasulphophthalocyanine co-ordinated to manganese-, iron-, cobalt-,nickel-, or copper-(=) has been found127 to be equal to that of cyanide.Azido-complexes (Et4N)2Mn(N3)4 and (Ph4As)Pd(N3), have been pre-pared.128 The preparation, far-infrared spectra, and thermal decompositionof Complexes of manganese, iron, cobalt, nickel, copper, and zinc with aminesand other nitrogen donors have beenCalorimetric studies of nitriloacetic acid complexes of divalent ions man-ganese to zinc show that the considerable differences in stability are due toentropy effects, the entropy of formation of the copper complex being par-ticularly large.Similar measurements of bipyridyl and tetraethylene-pentarnine complexes of these elements have also been reported.lS0One of the most interesting structural studies reported has established 131for the first time a trigonal prismatic co-ordination in tris(ck-1,Z-diphenyl-ethene-l,2-dithiolato)rl~enium(m). It has been suggested that, by analogywith this compound, supported by magnetic e.s.r., and polarographic studies,the complexes ML,- M = Cry Mo, W; L = toluene-3,4-dithiol, S,C,Ph,, orS,C,(CF,),] and [L = toluene-3,4-dithiol, S2CzPh2, or maleonitriledithiolate] also have this form of six-~o-ordination.~~~The oxidation of ReBr, in concentrated HBr leads 133 to a variety ofproducts depending on the cation present, e.g., Cs[ReOBr,], (Ph4As),ReBr,.Thiourea, acetylacetone, and mixed phosphine acetylacetone complexes ofrhenium( DI) have also been described.134 A number of complex technetiumoxides have been prepared 135 containing technetium in all oxidation statesfrom (m) to (VII).Compounds containing [Re2C1J2- and [Re2Br,l2- ions have been preparedla4P. L.Orioli, M. DiVaha, and L. Sacconi, Chm. Comm., 1965, 103.126 R.L. Carlin and M. J. Baker, J . Ohm. SOC., 1964, 5008.126 D. Forster and D. M. L. Goodgame, J . Chem. SOC., 1965, 263, 268.la8 W. Beck, K. Feldl, and E. Schuierer, Angew. Chem. Internat. Edrt., 1965, 4,439.la0 I. S. Ahuya, D. H. Brown, R. H. Nuttall, and D. W. A. Sharp, J . Inorg. NuclearOh., 1965, 27, 1105, 1625; J. R. Allen, D. H. Brown, R. H. Nuttall, and D. W. A.Sharp, ibzd., pp. 1305, 1865.130 J. A. Hull, R. H. Davies, and L. A. K. Staveley, J. Chem. SOC., 1964, 5422;R. L. Davies and K. W. Dunning, ibid., 1965, 4168; P. Paoletti and A. Vacca, ibid.,1964, 6051.Is1 R. Eisenberg and J. A. Ibers, J . AwAr. Clzern. SOC., 1965, 87, 3776.E. I. Stiefel and H. B. Gray, J . Amer. Chem. SOC., 1965, 81, 4012.lS3F. A. Cotton and S. J. Lippard, Inorg.Chem., 1965, 4, 1621.lS4 L. I. Evteev, Rws. J. Inorg. Chem., 1964, 9, 336; D. E. Grove, N. P. Johnson,lS5 C. Keller and B. Kanellakopulos, J . Inorg. Nuclear Cbm., 1965, 27, 787.J. H. Weber and D. H. Busch, Inorg. Chem., 1965, 4, 469.C. 5. L. Locke, and G. Wilkinson, J . Chem. SOC., 1965, 490176 INORGANIC CHEMISTRPand shown to have the structure (I). Each rhenium is surrounded by asquare-planar array of cholorines, the dimer being formed by a rhenium-rhenium bond (Re-Re = 2.24 A in the chloride). The chlorines are in theeclipsed configuration; and this is said to be necessitated by the formation ofa S-bond between the rhenium atoms. This is perhaps the best evidencepresented to date for the existence of &bonds. (NH,),Tc,C18 is virtuallyisostructural with the rhenium analogue.136 The trimeric species [Re3Xl2I3-;[Re3Xll]2- (X = C1 or Br), and [Re,Br,,]- are well established, and additioncompounds, e.g., Re3XgL, for many unidentate ligands L, Re,Cl,(acety-lacetone),, Re,Cl,(SCN),(dithiocarbamate), etc., have been ~repared.13~ The[Re3Brl1l2- ion has been shown to have a structure similar to that of thech10ride.l~~ Compounds of empirical formula M,IRe,Br, ca,n be prepared 139but it has been shown that crystals contain Re,Br, and [ReBr612- units.Bonding in these clusters has been discussed 140 and the magnet,ic and massspectrometric properties of rhenium(1rr) chloride ~0nsidered.l~~It has been suggested that rhenium(1v) chloride is trimeric, based on itsmagnetic properties; on the other hand technetium(1v) chloride is an octahe-dral polymer, (Tc-Tc = 3.59 A).l42 When pyridine (py) is reacted 143 withrhenium(1v) iodide some Re1,py is formed as well as ReI,py2; the former isdiamagnetic and is formulated as Re,I,py,.In the same system, bipyridylforms Re,I, (bipyridyl),.Re205 and Cd,Re207 have been prepared.144 Following the prepara-tion 145 of ions [ReX,O]- (X = C1, Br, I) it is suggested that earlier formu-lations [ReBr,(H,O,)]- and [ReBr,]- are wrong. Cs2ReOC15 can be made 146F. A. Cotton, N. F. Curtis, B. F. G. Johnson, and W. R. Robinson, Inorg. Chem.,1965,4,326; F. A. Cotton and C. B. Harris, ibid., p. 330; F. A. Cotton and W. K. Bratton,J . Amr. C h m . SOC., 1965, 87, 21.13' B. H. Robinson and J. E.Ferguson, J . Chem. SOC., 1964, 5683; F. A. Cotton,S. J. Lippard, and J. T. Mague, Imrg. Chem. 1965, 4, 508.138 M. Elder and B. R. Penfold, Nature, 1965, 205, 276.13* F. A. Cotton and S. J. Lippard, Inorg. Chem., 1965, 4, 69.14O J. E. Fergusson, B. R. Penfold, M. Elder, and B. H. Robinson, J . Chem. Soc.,141 D. Brown and R. Colton, Austral. J . Chem., 1965, 18, 441; K. Rinke and H.142 R. Colton and R. L. Martin, Nature, 1965, 205,239; M. Elder and B. R. Penfold,ld4 S. Tribalat, D. Delafosse, and C. Piolet, Compt. rend., 1965, 261, 1008; P. C.Donohue, J. M. Longo, R. D. Rosenstein, and L. Katz, Inorg. Chem., 1965, 4, 1152.1osF. A. Cotton and S. J. Lippard, Chm. Comm., 1965, 245.146 R. Colton, Austral. J . Chem., 1965, 18, 435.1965, 5500; F. A.Cotton, Imrg. Chm., 1965, 4, 334.Schiifer, Angew. Chem. Internat. Edn., 1965, 4, 148.Chem. Comrn., 1965, 308.C. Furhi and G. CiulIo, J . Imrg. Nuclear Chem., 1965, 27, 1167MABBS AND MACHIN: THE TRANSITION ELEMENTS 177from rhenium(v) chloride in ~ZM-HCI; it oxidises in air to Cs,ReOCI,. Somerhenium( v) amine and biguanide complexes have been synthesised.l*7Only three of the five predicted infrared frequencies but all of the Ramanfrequencies were observed in a study148 of rhenium(vn) fluoride. Thestructures of a number of mixed oxides containing rhenium(m) have beendetermined,l*D their general formula, being A,nRe2V11M1102. Alkali- andalkaline-earth metal salts of penta- and hexa-oxorhenate(m) have also beenprepared.l5oIron, Ruthenium, aad Osmium.-A review of the chemistry of osmiuma,nd its compounds has appeared during this year.151In the course of the reaction between Fe(CO), and amines, a t room tem-perature, the following three species were observed to appear successivelyin time ; >NH+-CO-Fe( CO),-, HFe( CO),- and >NH-Pe( C0)4.152 Withthe constrained phosphite ester, 4-methyl-2,6,7-trioxa-l-phosphabicyclo-[2,2,2]octane, mono- and di-substituted complexes of Fe(CO)6 have beenobtained.153 The reduction of RuCl,(CO) 2(Ph3P)2 with zinc in dimethyl-formamide, under a pressure of carbon monoxide, gave Ru(CO),(Ph,P)This latter compound can then undergo a series of oxidative additions, withreagents such as iodine, with the loss of one carbon monoxide group.15Q Anew series of hydride-aryl complexes typified by cis-[RuH( C1 ,,H,) ,( PP)2](where PP = Me,PCH,CH,PMe,), has been reported.155 Pyrolysis of thesecompounds can give [Ru(PP),], the physical properties of which are con-sistent with hydride transfer, from an alkyl side-chain of the ligand, to themetal atom.The Mossbauer spectra of Na[Fe,(CO),,Hj and Fe,(CO),, showthat in each compound only two of the iron atoms are eq~iva1ent.l~~ Whencoupled with X-ray data, these spectra suggest that the compounds havebridged triangular structures.Complexes with the general formula FeL,X,, (where L = 2,2'-bi-2-imidazoline, Ph3As0, Ph,PO, or quinoline, and X = halide), have beenprepared. Similar complexes of Con, NiII, and Cu' have also been reportedwith 2,2'-bi-2-imidazoline and spectral measurements used to show that thisligand occupies about the same position as NH, in the spectrochemicalseries.157 The iron-Ph3P0 and -Ph,AsO complexes are isomorphous withthe corresponding cobalt compounds, which are known to be tetrahedral.With 8-aminoquinoline as ligand, complexes of the types MLCl,, (whenM = FeII, Cu'I, CdII, or Znrr) and ML,X2, (when M = CoTr, Nil1, Curr,147 J.H. Beard, J. Casey, and R. K. Murmann, I.norg. Chem., 1965, 4, 797; M. M.14* H. R. Claassen and H. Selig, J . Chern. Phys., 1965, 43, 103.J. M. Longo, L. Katz, and R. Ward, Imrg. Chern., 1965, 4, 235.lS0 R. Scholder and K. L. Huppert, 2. amrg. Ch., 1964, 334, 209.161 W. P. Griffith, Quart. Rev., 1965, 19, 254.W. F. Edgell, M. T. Yang, B. J. Bulkin, R.Bayer, and N. Koizumi, J . Amer.lSs J. G. Verkade, R. E. McCarley, D. 0. Hendricker, and R. W. King, Inorg.16* J. P. Collman and W. R. Roper, J . Amer. Chem. Soc., 1965, 87, 4008.16b J. Chatt and J. M. Davidson, J. CJLem. SOC., 1965, 843.lssN. E. Erickson and A. W. Fairhall, I m g . Chern., 1965, 4, 1320.117 D. Forster and D. M. L. Goodgame, J . Chem. SOC., 1965, 454; J. C. Wang andRay, J . Imrg. Nuclear Chem., 1965, 27, 2193.Chem. SOC., 1965, 87, 3080.Chem., 1965, 4, 228.J. E. Bauman, jun., I w g . Chem., 1965, 4, 1613178 INORGANIU CHEMISTRYCdn, or Znn and X = C1-, Br- C10,- or NO,-) have been obtained.158 Thefirst example of tetrahedral iron(=) with the metal bonded to four oxygenatoms has been reported to occur in bis( dipivaloylmethanido)iron(n) .I59The measurement of the magnetic moment of (Fe salen)NO, (where salen =NN'-bis-salicylidene-ethylenediamine), over a temperature range, indicatesthe existence of a spin-free-spin-paired equilibrium.laO Nitrosyl thio-cyanates, aryl and alkyl mercaptides of iron(=) and cobalt(=) have beenisolated and then treated with tertiary phosphines or stibines to give thecomplexes M(NO),LR, (where L = phosphine or stibine and R = NCS-,C,H,S-, or C,H5S-).1a1In [Fe(CN),NOI2- the electronic structure is reported to be dominatedby the strong FeNO bond and the order of the energy levels should bezz,yx < xy < n*NO < xz - y2 < z2.16, For [Fe(CN),N0J3- the measure-ment of the e.8.r.14N hyperbe coupling tensor leads to the conclusion thatthe unpaired electron is mainly associated with the dzl orbital, the Fe-N-0direction being the a ax is.^^^ The iron( II) complex of 4,4',4",4"'-tetrasul-phophthalocyanine has been shown t o be a reversible oxygen-carrier in thesolid state.In solution, at neutral pH, it was not oxidised to ~ o D ( I T I ) . ~ ~ ~The preparation of RuPcClz and IrPcCl,, (where Pc = phthalocyanine),and a general discussion of the spectra of transition-metal phthalocyanineshas also been given.lg5 An investigation, over a temperature range, of therelative intensities of the C-N stretching vibration in the complexesFe(phen) ,( SCN) and Fe( bipy) 2( SCN) 2, show that they follow similar curvesto the magnetic moments. However, the infrared spectral evidence tendsto rule out the previous suggestion of a polymeric structure, with both ionicand co-ordinated thiocyanate g r 0 ~ p s .l ~ ~ The infrared spectra of the com-pounds Fe(C0)&3g2X, are reported to indicate that they consist of mono-meric ch-Fe( CO),( HgX) 2, in which there are two Pe-Hg bonds.ls7 Reactionof ruthenium and platinum salts with stannous chloride gave complexm ofthe type [MClz(SnC13)2]2-, in which SnC1,- behaves in a similar manner to achloride ion.168The compound Fe(NO,)P,O, has been prepared and formulated as(NO+)[Fe(NO,)&. When it is sublimed in vaxuo, there appears to be astructural change, probably to (NO,+)Fe(NO,),]-. The vapour-phasereaction between Fe(CO), and NO2 is reported to give [Fe(NO,)]O.l69168 J. C. Fanning and L.T. Taylor, J. Inorg. N&ar Chem., 1965, 27, 2217.158 J. P. Fackler, D. G. Holah, D. A. Buclhgham, and J. T. Henry, Inorg. Chem.,16oA. Earnshaw, E. A. King, and L. F. Larkworthy, Chem. C m . , 1965, 180.161 W. Hieber, J. Bauer, and 0. Neumair, 2. anorg. Chem., 1966, 335, 250.168 P. T. Manoharan and H. B. Gray, J . Amer. Chem. SOC., 1966, 87, 3340; H. B.168 D. A. C. McNeil, J. B. Raynor, rand M. C. R. Symons, J . Chem. SOC., 1965, 410.164 J. H. Weber and D. H. Busch, Inorg. Chern., 1965, 4, 469; D. Vonderschmitt,165 B. D. Berezh and G. V. Sennikova, Dokludy A M . Nauk S.S.S.R., 1964, 159,166 W. A. Baker and (3. T. Long, Chem. Cmm., 1965, 368.167 D. M. Adams, D. J. Cook, and R. D. W. Kemmitt, Nature, 1966, 205, 689.168 J. F. Young, R.D. Gillaxd, and 0. W m o n , J. Chem. SOC., 1964, 6176.16eC. C. Addison, B. F. G. Johnson, and N. Logan, J. Chm. rSoc., 1965, 4490;1966, 4, 920.Gray, P. T. Manoharan, J. Pearha, and R. F. Riley, Chmn. Convna., 1965, 62.I(. Bernauer, and S. Fallab, Helv. Chim. Ada, 1965, 48, 961.1127.C. C. Addison, P. M. Boorman, and N. Logan, ibid., p. 4978MABBS AND MAUHIN: THE TRANSITION ELEMENTS 179Complexes of NN-dimethylethylenedamine N-oxide with iron(m) and otherbi- and ter-valent transition-metal ions have been reported.lT0 The mag-netic properties of (Fe salen),O and (Fe salen)X, (where X = Cl- or Br-)have been investigated and the behaviour of the " oxide " interpreted onthe basis of spin-spin interaction in a binuclear c0rnp1ex.l~~ A series ofnitrosylruthenium(m) complexes containing nitrato- or aquo-groups hasbeen de~cribed.l7~ The main product of the reaction between rutheniumor osmium chlorides and 1,2-dicyanobenzene, at -280" c, was found tobe PcMCI[C,H,(CN),].~~~ In the complexes MCl,(Et,S), (where M = Ru,Rh, or Ir), the stability of the M-S bond is reported to be in the orderRh > Ir > Ru.In this same work the compound [RuCl,(Et,S),], waaisolated and its room-temperature magnetic moment found to be 0-95 B.M.174Pure u- and p-RuCl, have been prepared from ruthenium metal and0hl0rine.175 The preparation of a number of osmium nitrido-complexes hasbeen reported and their infrared spectra used to suggest possible s t r u c t ~ r e s . ~ ~ ~Cobalt, Rhodium, and Iridium.-The reaction of rhodium trichloridewith triphenylphosphine, in non-alcoholic oxygen-containing solvents, suchas dimethylformamide, has been shown to give [ RhC1( CO)( PPh,) Thisreaction is similar to that which occurs in alcohols.Contrary to this,(Ph,P),RhCl has been prepared from RhCl,, using ethyl alcohol as a sol-vent.178 Complexes containing silicon hydride residues have been reportedto be produced in the reaction between SiH,I and [Co(CO),]- and between[ (Ph,P),Ir(CO)Cl] and silicon hydride~.l7~A large number of complexes of the type CoLnX2 (where L = amine,X = halide or pseudo-halide), have been isolated and their structures dis-cussed on the basis of infrared, ultraviolet, and visible spectra and magnetioproperties.lsO Cobalt(=) complexes with Schif€ bases have also been inves-tigated and their structures discussed.Depending on the Schif€ base used,octahedral, tetrahedral, or five-co-ordinate Complexes can be obtained.181Recent investigations32 have ruled out a previous suggestion that the170 J. T. Summers and 5. V. Quagliano, Inorg. Ohm,. 1964, 3, 1767.171 J. Lewis, F. E. Mabbs, and A. Richards, Nature, 1965, 207, 865.17$ D. Scargill, C. E. Lyon, N. R. Large, and J. M. Fletcher, J . Inorg. NuchrChem., 1965, 27, 161; J. M. Fletcher and J. L. Woodhead, ibid., p. 1517.17aI. M. Keen and B. W. Mderbi, J . Inorg. Nuclear Ohem., 1965, 27, 1311.17c J. E. Fergusson, J. D. Karran, and S. Seevaratnam, J. Chm. SOC., 1965, 2627.171i K. R. Hyde, E. W. Hooper, J. Waters, and J. M. Fletcher, J.Less C n176 W. P. GrSth, J. Chem. SOC., 1966, 3694; G. W. Watt and W. C. McMordie, jun.,177 A. Rusina and A. A. VlEek, Nature, 1965, 208, 295.178M. A. Bennett and P. A. Longstaff, C i ~ m . Comm., 1965, 846.179 A. J. Chalk and J. F. Harrod, J . Amer. Chem. SOC., 1965, 87, 16; B. J. Aylettand J. M. Campbell, C M . Conzm., 1965, 217.180 N. H. Agnew and L. F. Larkworthy, J . Chem. SOC., 1965, 4669; H. C. A. King,E. Koros, and S. M. Nelson, W., 1964,4833; S. M. Nelson and T. M. Shephard, J. Inorg.N w k w Chem., 1965, 27, 2123; J. R. Allan, D. H. Brown, R. H. Nuttall and D. W. A.Sharp, ibicl., p. 1305; I. S. Ahuja, D. H. Brown, R. EL. Nuttall, and D. W. A. sharp, as., p. 1625; W. R. McWhinnie, ibid., p. 1619; D. P. Graddon and E. C. Watton, Austral.J .Chem., 1965, 18, 507; D. B. Fox, J. R. Hall, and R. A. Plowman, &id., p. 691.lS1 L. Srtccloni, M. Ciampolini, and G. P. Speroni, Inorg. Chern., 1965, 4, 1116;R. W. Oehmke and J. C. Bailar, jun., J . Inorg. NzccEeccr Chem., 1965,27,2199; H. Nishi-kwa and S. Yamada, Bull. Chem. SOC. Japan, 1965,3$, 1506; L. Sacconi, M. Ciampolini,and G. P. Speroni, J . A m p . Chern. SOC., 1965, 87, 3102.Met&, 1965, 8, 428.J . Imrg. Nuckar Chem., 1965, 27, 2013180 INORGANIC CHEMISTRYcobalt(@ complex with NN'-bis-salicylidene-ethylenediamine contains anaquo-bridge. The infrared spectra of the mono-nitric oxide adducts of thiscomplex, and some substituted derivatives, indicate that a conjugatedsystem can extend from the substituent to the NO molecule, v i a the metal.1s2X-Ray crystallographic studies, on bis- (2,5-dithiahexane)cobalt(n) perchlor-ate, have shown the perchlorate groups to be co-ordinated to the cobalt.183Infrared studies on the compounds CoL,(NO,), (where L = or-picoline,quinoline, isoquinoline, or pyridine N - ~ x i d e ) , ~ ~ ~ and on (NO+)[CO(NO,)~]-,~~~indicate that the nitrate group is acting as a bidentate ligand.Measurementof the room-temperature magnetic moment of 4,4',4'',4"'-tetrasulpho-phthalocyaninecobalt(n), a t different field strengths, indicates that there isconsiderable intermolecular interaction present.186 However, in aqueoussolution the magnetic moment was found to be 1.88 B.M., leading to theconclusion that, here, the cobalt is simply spin-paired. The effect of addingdonor ligands was reported to only slightly reduce the magnetic moment.The e.s.r.spectra of or- and #l-coba.lt phthalocyanine, diluted in the corre-sponding zinc and nickel derivatives, have been investigatedP87The first example of a six-co-ordinate cobalt@) complex containing onlymonodentate sulphur ligands has been isolated as the hexa-NN'-dicyclo-hexylthioureacobalt(rr) ion.18* Complexes of the cationic ligands, #l-amino-ethyltrimethylammonium and y-aminopropyltrimethylammonium, of thetype [ML6](C10J8 (where M = ColI or Nil1), have been reported.l89 Avariety of physical measurements on the compounds [ CoLJClO,) , (whereL = trimethylamine N-oxide or tetramethylguanidine), indicate that thecobalt is tetrahedrally co-ordinated.lgO A series of cobalt(11)-8-hydroxy-quinoline complexes has been isolated, in which the ligand can occuras either a neutral and/or a protonated bidentate chelating or bridgingThe effect of a variety of substituents, on the optical rotatory dispersionof some CoII, Nil1, and CuII Schiff base complexes has been reported.19zOptical rotatory dispersion and circular dichroism have been used to charac-terise, and in some cases determine the absolute configuration of, ColI1ammine and amino-acid complexes.193 The first amino-acid complexes ofrhodium(m), namely p-( +)- and #l-( -)-tris-[~( +)-alaninato]rhodiumO,group .l 91leap.C. Hemlett and L. F. Larkworthy, J. Chem. Soc., 1965, 882; A. Emhaw,183 F. A. Cotton and D. L. Weaver, J. Amer. Chem.SOC., 1965, 87, 4189.184 R. L. Carlin and M. J. Baker, J. Chem. SOC., 1964, 5008; A. B. P. Lever, Inorg.186 J. H. Weber and D. H. Busch, I w g . Chem., 1965, 4, 469, 472.187 J. M. Assour and W. K. Kahn, J . Amer. Chem. SOC., 1965, 87, 207.188 G. Yagupsky and R. Levitus, Inorg. Chem., 1965, 4, 1589.J. V. Quagliano, J. T. Summers, S. Kida, 8nd L. M. Vallerho, Imrg. Chem.,1964, 8, 1557.190 R. Longhi and R. 8. Drago, Inorg. Chem., 1965,4,11; R. S . Drago, J. T. Donoghue,and D. W. Herlocker, ibid., p. 836.191S. Lenzer, J. Chem. Soc., 1964, 5768.1 9 1 A. P. Terent'ev, G. V. Panova, and E. G. Rukhadze, J. Gen. Chem. (U.S.S.R.),1964, 84, 3049, 3055, 3060.A. M. Sargeson and G. H. Searle, Inorg. Chem., 1965, 4, 45; B. E. Dough andS. Yamada, ibid., p.1561; K. Garbett and R. D. Gillard, J. Chem. Soc., 1966, 6084.P. C. HewIett and L. F. Larkworthy, ibid., p. 4718.Ohm., 1965, 4, 1042.C. C. Addison and D. Sutton, J. Chem. SOC., 1964, 5563MABBS AND MACHIN: THE TRANSITION ELEMENTS 181have also been reported.194 The circular dichroism spectra of a number ofcobalt(rn) amine complexes have been measured and discussed in terms ofthe properties of the ligands and the symmetry of the ligand field>95However, low-temperature single-crystal spectral studies on the complex(-J-)[Co en,]Cl,NaCl,GH,O have raised some doubts as to the applicabilityof the above interpretations.lgsThe ultraviolet irradiation of [Co(diam),]Cl, (where diam = ethylene-diamine, propylenediamine, or butylenediamine), in aqueous solution, hasbeen shown to give mainly cobalt(=), ammonia, an aldehyde, and thediamine.197 Complexes of the type L,X,Rh-HgY, (where L = Ph,AsMe;X = C1 or Br, Y = F, C1, Br, or I), containing an Rh-Hg bond, havebeen prepared by the reaction of L,X,Rh-H with mercuric, mercurous,or organo-mercury compounds.Similarly ( Ph,P) 2(CO)C1,1r-HgCl wasprepared from (Ph,P),(CO)CIIr and HgC1,.Ig8 The reaction of rhodium oriridium salts with SnC1, gave the binuclear complexes [Rh2C1,(SnCl,),]4- and[ Ir2Cl6( SnCl,)4]4-. Neutral complexes containing (SnCI,) - together withPh,P, Ph,As, or diolefins can also be prepared.168(where X = C1, Br, I), [Rh,(CO),X,I2- (where X = C1, Br) and [Rh(CO)14]-,have been isolated. On the basis of infrared spectral evidence, the RhIcomplex was assigned a cis-square-planar structure, whilst the binuclearcomplex is thought to contain halogen bridges.lg9 The two isomers ofcis-[Rhpy4Br,]Br,6H,0, reported previously, have now been shown tobe trans-[ RhPy4Br,]Br,6H ,O (yellow) and trans-[ Rhpy,Br ,I( H 5O JBr,(orange).200 The formation of a hydridic species, by the reduction of thetrans-dichlorotetrapyridinerhodium( m) ion with borohydride or hypophos-phorous acid, has been reported.201 The reaction of triphenylstibine withK31rBr6 has led to the isolation of the following complexes: K[IrBr,L,],IrBr3L2, IrBr3L3, H[IrBr,L,], and I~HBI-,L,.~O~ The magnetic moment ofCs,RhCl, has been measured over the temperature range 78-300 O c andthe results interpreted in terms of an electron delocalisation parameterK = 0.7 and a spin-orbit coupling constant of 990 ~m.-l.~O~ The preparationand magnetic behaviour of RhF,, IrF5, and the previously unknownCsRhF, have been reported.204Nickel, Palladium, and Platinum.-The preparation of complexes of thetype Ni(PF,), and Ni(CO),(PF,),, (where 0 < x < 4), using a number oflg4 J.H. Dunlop and R. D. Gillard, J . Chem. Soc., 1965, 6531.lg6 R. A. D. Wentworth and T. S. Piper, Inorg. Chem., 1965, 4, 202; S. F. Masonand B. J. Norman, Chem. Comm., 1965, 48, 73; A. J. McCaffrey, S. F. Mason and B. J.Norman, &id., pp. 49, 132.lg6 R. Dingle, Chem. Cornm., 1965, 304.lD7 D. Klein and C. W. Moeller, Inorg. Chem., 1965, 4, 394; W. C. Taylor and C. W.Moeller, &id., p.398.lD8 R. S. Nyholm and K. Vrieze, J . Chem. Soc., 1965, 5331, 5337.ls9 L. M. Vallerino, Inorg. Chem., 1965, 4, 161.%O0 D. Dollimore, R. D. Gillard, and E. D. McKenzie, J . Chem. SOC., 1965, 4479.%OlB. N. Figgis, R. D. Gillard, R. S. Nyholm, and G. Wilkinson, J. Chem. Soc.,A new series of halogenocarbonyl anions with formulations [Rh( CO)1964, 5189.A. Araneo and S. Martinengo, Cfazzettu, 1965, 95, 825.I. Feldman, R. S. Nyholm, and E. Wakton, J . Chem. SOC., 1965, 4724.=04 N. Bartlett and P. R. Rao, Chem. Comm., 1966, 252; J . H. Holloway, P. R.Rao, and N. Bartlett, ibid., p. 306182 INORGANIC CHEMISTRYMerent methods, has been described.205 Using radioactive phosphorus,the reaction :Ni( PCI,), + 4PF, + Ni( PF& + 4PC1,has been shown to proceed wia ligand- rather than halogen-exchange.206In the reaction between P2CI, and Ni(CO), a t Ooc, a variety of compoundsis formed, depending on the ratios of the reactants.In the compoundsproduced? P2CJ4 can act as either a mono- or bi-dentate ligand.207 With aconstrained phosphite ester, substitution products of Ni(CO),, of the typeN~P(OCH2),C?Me],(CO),,, (where x = 1, 2, 3, or 4), have been preparedand characterised. Trialkyl phosphite derivatives of NiO, of the typeNi[P(OR)&, have been obtained by the reduction of the correspondingNin complexes with graphite-potassium.208 The reduction of K,Ni(CN),with molecular hydrogen is reported to give K4Ni2(CN), and hydrogencyanide.209A number of five-co-ordinate NiII complexes containing quadridentatephosphorus or arsenic ligands have been prepared and assigned trigonalbipyramidal structures,210 whilst some five-co-ordinate Schiff base complexeswe reported to have distorted square pyramidal structures.211 The structuresof other nickel(=) SchifF base complexes have been deduced from spectraland magnetic measurements, and the structures discussed in terms of thecomposition of the ligands.212 When dilute solid solutions of bis- (N-methyl-salicylaldiminato)nickel(n) in, the corresponding zinc(n) complex are formed,the nickel complex assumes the penta-co-ordinate stereochemistry of thehost lattice.213 The occurrence of monomeric or polymeric /Miketonecomplexes of nickel(=) has been shown to depend on the nature of the sub-stituents on the #?-diket~ne.~l~ The position of the square planar + tetra-hedral equilibrium in the complexes Ni[ R,COCH(NHR)R,] 2, was also foundto be dependent on the nature of both Ry and R,,a15 As in the case ofcobalt@), there have been a number of reports of the preparation and assign-ment of the structures of compounds of the type NiL,X, (where L is ana05 R.J. Clark and E. 0. Brimm, Inorg. Chem., 1965, 4, 651; J. R. Olechowaki,C. G. McAlister, and R. F. Clark, ibid., p. 246; T. Kruck and I(. Baur, Chm. Ber.,1965, 98, 3070.ao6 R. J. Clark, P. I. Hoberman, and E. 0. Brimm, J. Inorg. Nuclear Chm., 1965,27, 2109.a07 C. B. Lindahl and W. L. Jolly, Inorg. Chem., 1964, 3, 1634.ao8 K. A. Jensen, B. Nygaard, G. Elisson, and D. H. Nielsen, Acta Chm.Stand.,1965, 19, 768.2oQ Jin Sun Yoo, E. Griswold, and J. Kleinberg, Imrg. Chem., 1965, 4, 366.210 G. Dyer, J. G. Hartley, and L. M. Ventmzi, J. Chem. Soc., 1965, 1293; G. Dyerand L. M. Venanzi, ibid., p. 2771; G. Dyer and D. W. Meek, Inorg. Chem., 1965, 4,1398; G. S. Benner, W. E. Hatfield, and D. W. Meek, ibid., 1964, 3, 1544.211 L. Sacconi, P. Nannelli, N. Nardi, and U. Campigli, Inorg. Chm., 1965, 4, 943.21a N. F. Curtis and D. A. House, J . Chem. Soc., 1965, 6502; A. Chakravorty, J. P.Fennesey, and R. H. Holm, Inorg. Chem., 1966, 4, 26; A. Chahavorty, {bid., p. 127;L. Sacconi, P. Nannelli, and U. Campigli, ib;d., p. 818; A. K. Majumdar and B. C.Bhattacharyya, J . Inorg. Nuclear Chem., 1965, 27, 143; E. J. Olszewaki and D. T.Martin, ibid., p.345; B. Kirson and F. Kassirer, Bull. Soo. chim. France, 1966, 673;E. G. Jkiger, 2. anorg. Chem., 1965, 337, 80.a13 L. Sacconi, M. Ciampolini, and G. P. Speroni, J . Amer. Chm. ~ o c . , 1966, 87,3102.a14 L. Wolf and E. Butter, 2. anorg. Chm., 1965, 339, 191.a16G. W. Everett, jun., and R. H. Holm, J . Amer. Chem. Soc., 1965, 87, 2117MABBS AND MACHIN: THE TRANSITION ELEMENTS 183amine, n can be 1, 1.5, 2, 3, 4, or 6 and X = halide or pseudohalide)?16Co-ordinated perchlorate, tetrafluoroborate, and borohydride anions havebeen reported to occur in the complexes Ni(diamine)B(C10,)2, NiPy,X,(where X = ClO,- or BF,-), and NiA(BH4)S (where A = tetradentateamiae or Schif€ base). Also infrared spectra indicate the presence of biden-tate nitrito-groups in Ki[Me2N(CH,)2NMe](N0,)2 and mono- or bi-dentatenitrate in Ni en2(N03), and [Ni en,N03]C10,.217The nuclear magnetic resonance contact shifts observed for the com-pounds Ni(Ph,P)2X2 (where X = halide), and NiL1L2 (where L, and L,are different aminotroponeimine ligands), have been interpreted in terms ofmetal-to-ligand n-bonding.21* The preparation of the bis( ct-di$hiodiketone)-,bis( dithioglyoxa1)-, and bis( dimercaptoethy1ene)-nickel@) complexes andsome of their chemical and physical properties have been reported.219 Theultraviolet and infrared spectra of nickel(n) ions, in KE'-KCN mixtures,have been interpreted in terms of the presence of Ni(CN),2- and Ni(CN)53-.No evidence was found for the formation of [Ni(CN)5F14- or [Ni(CN)6]4-.220The polarised electrqnic absorption spectra of crystals containing the[Ni(CN),I2- ion have been interpreted on the basis of a square-planar con-figuration in the ground state and a distorted tetrahedral configuration inthe excited state.221 The two forms of bis( benzoylmethylglyoxime)nickel(n)have been shown to be respectively, a crystalline and a disordered species,22anot cis- and &am-isomers as previously reported.A series of nitrile-nickel( 11) halide and perchlorate complexes, and mixed aquo-nitrile- andamine-nitrile-nickel( n) halides, have been isolated. The bis- and tetra-methylcyanidenickel(11) perchlorates have been s h ~ t m by infrared spectralstudies to contain co-ordinated perchlorate ions.223 The reaction between[M(CN0),I2- (where M = NPI, PdII, or Ptxl) and the phosphinee PR,(where R = Et, c6Hll, or Ph), gives the complexes (PR,),M(CNO),.Thesecomplexes have been assigned tram-square-planar structures on the basisof magnetic and dipole-moment rneasurements.224216 S. M. Nelson and T. M. Shepherd, J . Chem. SOC., 1965,3276; D. M. L. Go-odgame,M. Goodgame, and M. J. Weeks, ibid., 1964, 5194; A. B. P. Lever, S. M. Nelson, andT. M. Shepherd, Imrg. Chem., 1965, 4, 810; S. M. Nelson and T. M. Shepherd, ibid.,p. 813; L. M. Vallerino, W. E. Hill, and J. V. Quagliano, ibid., p. 1598; W. E. Bulland L. E. Moore, J. Inorg. Nuclear Chem., 1965, 27, 1341; A. B. P. Lever, ibid., p. 149;E. Uhlig and K. Staiger, 2. anorg. Chem., 1965, 336, 42, 179.N. F. Curtis, J. Chem.SOC., 1965, 924; D. M. L. Goodgame and M. A. Hitchman,Imorg. Chem., 1965, 4, 721; N. F. Curtis and Y. M. Curtis, ibid., p. 804; M. R. Rosenthaland R. S. Drago, ibid., p. 840; S. F. Pavkovic and D. W. Meek, ibid., p. 1091.21e D. It. Eaton and W. D. Phillips, J. Chem. Phys., 1966, 43, 392; E. A. Lalancetteand D. R. Eaton, J. Amer. Chenz. SOC., 1964, 86, 5145.G. N. Schrauzer and V. P. iXayweg, J. Amer. Chem. SOC., 1965, 8'9, 1483; 3585;G. N. Schrawer, V. P. Mayweg, and W. Heinrich, Inorg. Chent., 1965,4,1616; E. Hoyer,Chem. and Ind., 1965, 652.220 J. S. Coleman, H. Petersen, jun., and R. A. Penneman, Imrg. Chem., 1966,4, 135.221 C. J. Ballhausen, N. Bjerrum, R. Dingle, K. Eriks, and C. R. Hare, Inorg. Chena.,1965, 4, 514.222 K. A. Jensen, B.Nygaard, and R. B. Jensen, Acta Chem. Scand., 1965, 19,770.22% A. E. Wickenden and R. A. Krause, Inorg. Chern., 1965, 4, 404; A. V. Babaevaand Kh. U. Ikramov, RUM. J. Inorg. Chem., 1964, 9, 327, 330.224 W. Beck and E. Schwierer, C7xm. Ber., 1965, 98, 298154 INORGANIC CHEMISTRYWhen tetraphenylarsonium chloride was added to a methanolic-hydrochloric acid solution of palladium and tin in the ratio 1 :5,[Ph,As],[PdCl(SnCl,),] was precipitated.22j The reaction of [Pt(SnC1,),]3-with hydrogen, under pressure, gave [HPt(SnC1,),I3-. The compound isbelieved to be the first example of an anionic platinum hydride. Also,X-ray data on [Pt(SnC13),-J3- compounds have shown this anion to betrigonal bipyramidal, with all five tin atoms co-ordinated to the platinum.226Compounds of the type (R3P)2M(GePh3)2 (where M = PdII or PtII), havebeen prepared and the breaking of the &--M bond, with reagents such asiodine, hydrogen chloride, methyl iodide etc., The isolation oftrans-(Ph,P),PtCl,, by the addition of an acetone solution of mercuricchloride to a benzene-acetone solution of trans-bis( tripheny1phosphine)-platinum(=) hydrochloride, a t 0 OC, has been described.228 If the temperatureof the reaction mixture is allowed to rise, only the ck-isomer is obtained.A structural determination of platinum@) chloride has shown it tocontain Pt&1,2 units, with the chlorine atoms situated above the edges ofan octahedron of platinum atoms.229 The electronic absorption spectra ofMagnus's green salt and some of its anologues have been interpreted in termsof metal-metal interactions within the crystals.230 However, other authorsbelieve that the visible spectra arise from the ligand-field transitions of theani~ns.~~l From a study of the infrared spectra of the cis- and trans-isomersof Pt(NH,),CI, and Pt(ND,),Cl, it has been concluded that ligand-ligandinteraction occurs via a filled d-orbital of the platin~m.~3~The preparations of the acetate, benzoate, trifluoroacetate, and penta-fluoroproprionate complexes of palladium(=) have been described.Thefluorocarboxylate complexes were found to be monomeric and the othercomplexes trimeric in solution. The reaction of these complexes with amines,Ph,P or Ph,As gave tran~-Pd(0COR),L,.~~~ In the complexes MX,L[where M = PdII or PtII, X = C1-, Br-, or I- and L = (a-Me2NC6H,),PPhor (a-Me,NC,H,),P], it has been shown that only the phosphorus and oneof the nitrogen atoms of the ligands are bound to the metal ions, to givesquare-planar stereochemistry.234Complexes of nickel(m) of the type NiBr,(dp) and [NiX,(dp),]X, (wheredp = Me2PC2H,PMe, and X = halide), have been is0lated.2~~ Polaro-graphic and electron spin resonance measurements on complexes of thef 2 6 M .A. Khattak and R. J. Magee, Chem. Comm., 1965, 400.226 R. D. Cramer, R. V. Lindsey, jun., C. T. Prewitt, and U. G. Stolberg, J . Amer.227 R. J. Cross and F. Glocking, J. Chem. SOC., 1965, 5422; E. H. Brooks and F.228 A. D. Allen and M. C. Baird, Chem. and I n d . , 1965, 139.419 K.Brodersen, G. Theile, and H. G. Schnering, 2. anorg. Chem., 1965, 337, 120.230 J. R. Miller, J. Chem. Soc., 1965, 713.231 P. Day, A. F. Orchard, A. J. Thornson, and R. J. P. Williams, J . Chem. Phys.,252 K. Nakamoto, P. J. McCarthy, J. Fujita, R. A. Condrate, and G. T. Behnke,f S 3 T. A. Stephenson, S. M. Morehouse, A. R. Powell, J. P. Heffer, and G. Wilkinson,234 H. P. Fritz, 3. R. Gordon, K. E. Schwarzhaus, and L. M. Venanzi, J . Chem. SOC.,235 G. Booth and J. Chatt, J . Chem. SOC., 1965, 3238.Chem. Soc., 1965, 87, 658.Glocking, Chem. Comm., 1965, 610.1965, 42, 1973.I w g . Chem., 1966, 4, 36.J . Chem. SOC., 1965, 3632.1965, 5210MABBS AND MACHIN: T H E TRANSITION ELEMENTS 185type N~(O-SC,H,NH)~ (where n = 0, 1-, or 2-), indicate that the varyingvalues of n are best described in terms of changes in the oxidation states ofthe ligands, rather than of the metal The infrared spectra of somemixed cyano-amine complexes of palladium(=), and the first mixed cyano-complex of rhodium(=), i.e., Rhpy,(CN),C1,2H20, have been used to suggesttheir structures.The rhodium complex is thought to be polymeric with bothterminal and bridging cyanideThe preparation of [PtX,YZen] (where X = halide, Y = halide, OH-,CN-, Z = CN-, NO,, NO,, or OH-), has been described. Also the reactionof [PtX,(CN),en] with silver nitrate gives ([PtX,(CN),en],Ag}NO, it is re-p0rted.23~ The preparations have also been described of [Pd(NH,),Cl,]Cl,([Pd(NH,),]C1,[Pd(NH3)4Br,]Br,) ,239 and Pt(glyc),Cl (where glyc = theglycinate anion) .240Copper, Silver, and Gold.-The reaction between Ph,PAuCl and sodiumborohydride, in ethanol, resulted in the isolation of Au,(Ph3P),C1,3-5H20,which could then be converted into Au,(Ph3P),C1,4CH,0H in methanol.Both of these complexes are thought to contain four gold(0) and one gold(1)atoms, the diamagnetism being explained in terms of interaction between thegold(0) atomsS24l The complexes (triars)M-Mn(CO),, [(triars)M],Fe(CO),,and (triars)M-Co(CO), (where triars = a tri-tertiary arsine and M = Cu orAg) have been isolated.242 The preparation of the complexes LAu-Mn(CO),[where L = (PhO),P, (p-MeOC6H4),P, ( P - M ~ C ~ H ~ ) ~ ~ , Ph,As, or Ph,Sb],and Ph,PAu-Mn(CO),L1 (where L1 = Ph3P, Ph,As, (PhO),P, or pyridine),has been described and the force constants for the carbonyl groups in LAu-Mn(CO), have been calculated from the infrared spectra.243 (Ph,P),CuBH,has been prepared and reacted with HX (where X = ClO,, NO,, or BF,) togive (Ph,P),CuX, in which X is co-ordinated to the copper atom.Thereaction of (Ph,P),CuBH, with anhydrous hydrogen chloride, in benzene,gave Cu2C1,(Ph,P), as one of the products.244 Molecular-weight measure-ments on 1,3-dimethylfriazenocopper(1), in benzene solution, indicate that itis a tetramer, and two possible cyclic structures have been prop0sed.2~5Infrared spectral measurements on the complexes (Xpy) ,MC10, (whereX = 2-, 3-, or 4-cyano and M = CuI, AgI, AuI), have been used to show thatin the 3- and 4-cyano-pyridine derivatives, the metal is bound to the pyri-dine nitrogen, whilst in the 2-cyanopyridine derivative it is bound to the236 E.J. Stiefel, J. H. Waters, E. Billig, and H. B. Gray, J. Amer. Chem. SOC.,1966, 87, 3016.237 R. D. Gillard, J. Inorg. Nuclear Chem., 1966, 27, 1321.238 I. I. Chernyaev, N. N. Zheligovskaya, Lieh-T’i-k’eng and D. V. Kurganovic,Russ. J . Inorg. Chern., 1964,9,312; I. I. Chernyaev, A. V. Babkov, and N. N. Zheligov-skaya, ibid., p. 319.238 A. V. Babaeva and E. Ya. Khananova, Doklady Akad. Nauk S.S.S.R., 1964,159, 1209.240 A. A. Grinberg and Y. Kan, Doklady Akad. Nauk S.S.S.R., 1964, 154, 8.241 L. Malatesta, L. Naldini, G. Simonetta, and F. Cariati, Chem. Co?nm., 1965, 212.242 A. S. Kasenally, R. S. Nyholm, and M. H. B. Stiddard, J. Chem. SOC., 1966,243 A.S. Kasenally, J. Lewis, A. R. Manning, J. R. Miller, R. S. Nyholm, and244 F. Coriati and L. Naldini, Gazzetta, 1965, 95, 201; J. M. Davidson, Chem. and245 F. E. Brinckman, H. S. Haiss, and R. A. Robb, Inorg. Chem., 1965, 4, 936.5343.M. H. B. Stiddard, J. Chem. SOC., 1965, 3407.Ind., 1964, 2021.186 INORGANIC CHEMISTRYnitrile nitrogen.246 Similar measurements on some 2-aminopyridine deriva-tives of silver nitrate have shown that the ring nitrogen of Z-methylamino-pyridine is bound to the silver atom, whereas with 2-aminopyridine and2-amino-6-methylpyridine the metal is bound to both the ring and amino-nitrogen^.^^'The formation of binuclear or more highly polymeric copper(r1) carboxy-late compounds has been correlated with the p&-values and steric proper-ties of the carboxylic The magnetic properties of coppes(r1) ben-zoate, nitrobenzoate, and some adducts of these complexes have beenmeasured over the temperature range 80-300 The magnetic proper-ties of the anhydrous complexes seem to depend on the methods of prepara-tion, this phenomenon being interpreted in terms of the existence of bothbi- and poly-nuclear structures. A reinvestigation of the absorption spec-trum of single crystals of copper(I1) acetate monohydrate has revealed apreviously unreported band a t about 11,000 cm.-1 The assignment of thespectrum is discussed.250 Using a weakly coupled clmomophore model, asuccessful explanation of the absorption spectrum of copper(I1) acetatemonohydrate has been rep0rted.~51 Magnetic measurements on complexesof the type CuLX, (where X = C1 or Br and L = pyridine N-oxide or 4-substituted pyridine N-oxide), have been interpreted in terms of a bicuclearstructure, in which there is considerable magnetic exchange between thecopper atoms.252 On the basis of magnetic, visible, and infrared spectra,and molecular-weight measurements, binuclear structures have been pro-posed for the copper@) salts of acrylic, vinylacetic, and allylacetic acids,253for complexes of the type [ (ampy),Cu( OR)NOJ2 (where ampy = 2-aminopyri-dine, R = H, Me, Et, Prn, n-pentyl) 254 and CU,(M~CO,),(OCH,CH,NR,),.~~~Also, using the same criteria, highly polymeric structures have been postu-lated for Cu( OMe),, Cu( OMe)CI, and Cu( OEt)C1.256The magnetic moments of complexes of the type (CuX,)2- (whereX = GI, Br, and NCS) and [C~(tetramethylguanidine)~](CIO~)~ have beenreported and discussed in terms of departures from tetrahedral stereo-chemistry.257 The electron spin resonance spectrum of the (CUCI,)~- ionhas also been considered in detail5$ The preparations of complexes of the2a6F.Farha, jun., and R. T. Iwamoto, Inorg. Chern., 1965, 4, 844.Z47 E. Uhlig and 31. Bladler, 2. anorg. Chem., 1965, 338, 199.248 J. Lewis, Y. C. Lin, L. K. Royston, and R. C. Thompson, J . Chem. SOC., 1965,6464.249 J. Lewis and F. E. Mabbs, J. Chem. Soc., 1965, 3894; C . S. Fountain and W. E.Hatfield, Inorg. Chem., 1966, 4, 1368; A. Earnshaw and K. S. Patel, J . Inorg. NuclearChem., 1965,27,1805; V.V. Zelentsov, M. N. Volkov, V. M. Allenov, and T. G. Aminov,Russ. J. Inorg. Chem., 1965, 10, 306.250 C. W. Reimann, G. F. Kokoszka, and G. Gordon, Inorg. Chm., 1965, 4, 1082.261A. E. Hansen and C. J. Ballhausen, Trans. Furuday SOC., 1965, 61, 631.262 W. E. Hatfield, Y. Muto, R. B. Jonasson, and J. S. Paschal, Inorg. Chem.,1965, 4, 97; H. R. Schafer, J. C. Morrow, and El. M. Smith, J. Chem. Phys., 1965, 42,504.268 B. J. Edmondson and A. B. P. Lever, Inorg. Chem., 1966, 4, 1608.254 W. R. McWhinnie, J. Inorg. Nuclear Chern., 1965, 27, 1063.2 5 5 F. Hein and W. Ludwig, 2. unorg. Chem., 1965, 338, 63.2 5 6 C. H. Brubaker, jun., and M. Wicholm, J. Inorg. Nuclear Chem., 1965, 27, 59.Z57 R. Longhi and R. S. Drago, Inorg. Chem., 1965, 4, 11; L.Sacconi, M. CiampolmiZ 6 * M. Sharnoff, J . Chem. Phw., 1965, 42, 3383.and V. Ciampigli, ibid., p. 407; D. Forster and D. M. L. Goodgame, ibid., p. 823MABBS AND MACHIN: THE TRANSITION ELEMENTS 187type CuX2L, CuX2L2,nH20, CuXL2C104,nH,0 (where L = 4,6,4’,6’-tetra-methyl-Z,Z‘bipyridyl), Cu(bipyam) ,X2 (where bipyam = 2,2’-bipyridyla-mine) and copper( n) complexes of the tridentate ligand, pyridine-2-carboxy-aldehyde - 2 ’ - p yridylhy drazone , have been described. The structures ofthese compounds are discussed in terms of possible four-, five-, or six-co-ordination.259 Gold phthalocyanine 260 and ( Bun4N) 2[ Au(mnt) 2] 261 havebeen reported and their formulations based on the presence of gold(=).The silver(m) complex, Na5H2Ag(IO6),,16H,O, has been prepared bytwo methods.262 The ligand field spectra of [Cu(OH),]- and the ethylene-bisbiguanide complex of AgIII, in both the solid state and solution, have beenreported and discussed.263 The formation of the complexes [Au( CN) %X,]-(where X = C1, Br, or I), [Au(CN),Cl]- [Au(CN),]-, and HAu(CN),,2H,Ohas been described, and their infrared and Rarnan spectra used to suggestpossible structures.264 The electronic spectrum of the complex Au( dto) 2,(where dto = dithio-oxalate), has been assigned on the basis of the energylevels derived for [ N i ( d t ~ ) ~ ] ~ - - .~ ~ ~Zinc, Cadmium, and Mercury.-The preparation of the 2 : 1 amine : metal-halide complexes of both zinc and cadmium have been reported. The zinccompounds are considered to be neutral tetrahedral species, whilst thecadmium complexes seem to be best described as [Cd( amine),][CdX,].266The pyrazine adducts of zinc, cadmium, and mercury halides, of the typeMX, pyrazine, have been isolated and polymeric structures suggested.267Polymers with molecular weights in excess of 10,000 have been reported forthe dibutylphosphinate and dioctylphosphinate derivatives of zinc( n).268The Raman spectra of the monoiodide, monobromide, and monochloridecomplexes of mercury(I1) have been observed in aqueous solutions with highratios of Hg: halide.Some evidence for the formation of [Hg-l-Hg]3+was also found.269 Infrared spectra have been used to demonstrate theco-ordination, through sulphur, of the sulphite group to mercury.270 Thepreparation of mercuricarbamates has been reported.These complexes wereshown to be less susceptible to hydrolysis than the corresponding stannyl-carbamates.271)Kg W. R. McWhinnie, J . Chem. SOC., 1964, 6165; J. F. Geldard and F. Lions, Imrg.Chem., 1965, 4, 414; J. R. Hall, M. R. Litzow, and R. A. Plowman, Austral. J . Chew.,1965, 18, 1331.260 A. MacCragh and W. S. Koslii, J . Amer. Chem. SOC., 1965, 87, 2496.261 J. H. Waters and H. B. Gray, J . Amer. Chem. SOC., 1965, 87, 3534.2 6 z G. L. Cohen and G. Atkinson, Inorg. Chem., 1964, 3, 1741,263 R. S. Banerjee and S. Basu, J . Inorg. Nuclear Chem., 1965, 27, 363.2 6 4 J. M. Smith, L. H. Jones, I. K. Kressin, and R. A. Penneman, Imrg. Chem.,265 A. R. Latham, V. C. Hascall, and H. B. Gray, Inorg.Chem., 1965, 4, 788.*66 M. Goldstein and E. F. Mooney, J. Inorg. Chem., 1965, 27, 1601.267 H. D. Stidham and J. A. Chandler, J . Inorg. Nuclear Chem., 1965, 27, 397.26sV. Cresceni, V. Giancotti, and A. Ripamonti, J . Amer. C h m . SOC., 1965, 87,J. H. R. Clarke and L A. Woodward, Trans. Furday Soc., 1965, 61, 207.870 J. I. Bullock and D. ‘ x . Tuck, J . Chem. SOC., 1965, 1877.a71A. G. Davies and G. J. D. Peddle, Chem. Comm., 1965, 96.1966, 4, 369; L. H. Jones, ibid., 1964, 3, 1681.392; S. H. Rose and B. P. Blcyk, ibid., p. 20764. TRANSITION-METAL CARBONYLS ANDRELATED COMPOUNDSBy F. J. Kohl and J. Lewis(Department of Chemistry, The University, Manchester)Structure.-Reviews on the alkali-metal derivatives of the carbonyls 1 andthe r81e of organometallic compounds in co-ordination chemistry havebeen published.The infrared spectra of osmium dodecacarbonyl,3 rheniumand manganese decacarbony14 have been analysed by using the techniquediscussed by Cotton and Kraihanzel.5 The use of the overtone and com-bination bands in frequency assignment of metal carbonyls has beene~aluated.~, The infrared spectra of a variety of phosphine-substitutediron carbonyl compounds have been reported,' and the R'aman and infraredspectra of Ni(CO),[P(Ph),] have been interpreted.8 The infrared spectraof the molecules Ni(C180),, Ni(C180)3(C160) have been used to determinethe force constants in nickel carbonyl.9 The mass spectra of chromium,molybdenum, tungsten,lO manganese, and cobalt 11 carbonyls are reported.Loss of CO groups occurs in a stepwise manner and a major positive ionin the spectra of manganese decacarbonyl and cobalt octacarbonyl are thedimetallic ions Mn,+ and Co,+ respectively.The mass spectra of sub-stituted cyclopentadienyl carbonyls of cobalt, manganese, and vanadium l2also of cyclopentadienylmolybdenum nitrosyl carbonyl l3 have been deter-mined.A polymeric platinum carbonyl [Pt(CO),], has Been isolated as a purplecolloidal precipitate by the action of carbon monoxide and water on abenzene solution of [PtCI,(CO),] or as a brown crystalline solid from carbonmonoxide with dilute ethanolic solution of sodium chloroplatinite. Thecompound is unstable in air. A series of stable trimeric platinum clustershave been prepared by reaction of the carbonyl with phosphines.14 A newformulation has been suggested for Co,(CO)12 in which the cobalt atomsform a tetrahedral array;15 each cobalt atom has two terminal and twobridging CO groups and forms a direct metal-metal bond to another cobalt1 R.B. King, Adv. Organometallic Chem., 1964, 2, 157.2 F . G. A. Stone, Pure Appl. Chern., 1965, 10, 37.D. K. Huggins, N. Flitcroft, and H. D. Kaesz, Inorg. Chena., 1965, 4, 166.F. A. Cotton and R. M. Wing, Inorg. Chem., 1965, 4, 1328.F. A. Cotton and C. S . Kraihanzel, J . Amer. Chem. Soc., 1962, 84, 4432; Inorg.Chem., 1963, 2, 633.J. Lewis. A. R. Manning. 5. R. Miller, M. Ware, and F. Nyman, Nature, 1966, Y . 20'7, 142.7 A. Reckziegel and M. Bigorgne, J. Organometallic Chem., 1965, 3, 341.8 W.F. Edgell and M. P. Dunkle, Inorg. Chem., 1965, 4, 1629.@G. Bouquet and M. Bigorgne, Compt. rend., 1965, 261, 2865.10R. E. Winters and R. W. Kiser, Inorg. Chem., 1965, 4, 157.IIR. E. Winters and R. W. Kiaer, J . Phys. Chem., 1965, 69, 1618.12 R. E. Winters and R. W. Kiser, J. Organometallic Chem., 1965, 4, 190.13 R. E. Winters and R. W. Kiser, J . Phys. Chern., 1965, 69, 3198.l4 G. Booth, J. Chatt, and P. Chini, Chem. Comrn., 1965, 639.1 5 D. L. Smith, J. Chem. Phys., 1965, 42, 1460KOHL AND LEWIS : TRANSITION-METAL CARBONYLS 189atom. The monomeric compound Co(CO), has been identified by e.s.r.measurements.lBased on the structure of the ion [Fe3(CO),1H]-, Fe,(CO),, is formulatedas a triangular metal cluster in which one bridging group of the Fe2(CO)gsystem is replaced by an Fe(CO), gr0up.l' The structures of the carbonyland the ion [Fe,(CO),,H]- are then in agreement with expectations fromthe Mossbauer spectra.l* A new polymeric carbonyl [Re(CO)& has beenisolated by reaction of rhenium sulphide with copper in the presence ofcarbon monoxide :I9 the infrared spectrum indicates the absence of bridgingCO groups.The oxygen of the [Re(CO),]+ has been shown to be liableto 1 8 0 exchange with HZ80 whereas no exchange was observed withmolybdenum.20 The metal-metal distance and angular displacement ofd0 groups from the equatorial plane in manganese decacarbonyl has beendiscussed in terms of variation of d / p character to the bonds.21 It hasbeen suggested that the inert-gas configuration is exceeded in a manganesecarbonyl derivative which is formulated as a seven-co-ordinate complex[Mn(CO)5(NHMe)(NH2Me)].22 The crystal structure of cis-(diethylenetria-mine)molybdenum tricarbonyl has been determined and a bond-order-bond-length relationship deduced for metal-carbon bonds.23 The n-bondingin the M(CO), group has been discussed 24 and an attempt made to estimatethe n-acceptor ability of CO in the Group VIB ~arbonyls.~~ The X-raystructure of the compound [Fe2(C5H5),(CO),CNPh] confirms the pre-sence of a bridging isonitrile group.26 The structures of the compounds(CO),M*(PhCOMe) (M = Cr, W) are consistent with the formulation asmetal-carbene derivatives.27Photochemical Reactions.-A series of complexes W( CO) 5L, where L isaromatic or heterocyclic group is formed by photochemical reaction withtungsten carbonyl and the ligand.Infrared spectra indicate a symmetricalbonding to the arene and not to a fixed double bond.28 Photochemicalreaction of chromium and tungsten carbonyls with a variety of sulphidesand sulphoxides to give the compounds M(CO),L has been studied.29Irradiation of iron carbonyl with light or 6oCo y-rays in nitrobenzene yieldsa diamagnetic compound [ (CO) ,FeC,H,NO] in which iron-oxygen-nitrogen-metal bridges are p~stulated.~~ Photochemical substitution reac-tions of manganese decacarbonyl, to yield Mn,(CO),L (L = alkyl andaryl nitrile, pyridine, triphenylphosphine) and with butadiene to givel6 H. J. Keller and H. Wawersik, 2. Naturforsch., 1965, 20b, 938.l7 L.F. Dahl and J. F. Blount, Inorg. Chem., 1965, 4, 1373.lsN. E. Erickson and W. Fairhall, Inorg. Chem., 1965, 4, 1320.lS A. G. Osborne and M. H. B. Stiddard, J . Organometallic Chem., 1965, 3, 340.zo E. L. Muetterties, Inorg. Chem., 1965, 4, 1841.21 M. J. Bennett and R. Mason, Nature, 1965, 205, 760.z2 R. J. Angelici, Chem. Comm., 1965, 486.24 S. F. A. Kettle, Inorg. Chem., 1965, 4, 1661.25 G. R. Dobson, Inorg. Chem., 1965, 4, 1673.26 K. K. Joshi, 0. S. Mills, P. L. Pauson, B. W. Shaw, and W. H. Stubbs, Chem.2 7 0. S. Mills and A. D. Redhouse, Angew. Chem., 1965, 77, 1142.28 I. W. Stolz, H. Haas, and R. K. Sheline, J . Amer. Chem. SOC., 1965, 87, 716.2s W. Strohmeier, J. F. Guttenberger, and G. Popp, Chem. Bey., 1965, 98, 2248.30 E.Koerner v. Gustorf and M. J. Jun, 2. Naturforsch., 1965, Nb, 521.F. A. Cotton and R. M. Wing, Inorg. Chem., 1965, 4, 314.Comm., 1965, 181190 INORGANIC CHEMISTRYC,H,(CO) ,Mn-Mn(CO) 5y have been studied.3l Manganese decacarbonylpolymerises monoepoxides in U.V. light ;32 manganese and rhenium carbonyl,and phosphine-substituted rhenium carbonyls have been used as poly-merisation catalysts in carbon tetrachloride solution.33Nitrogen, Phosphopus, and Arsenic Derivatives.-Tetrakis(dimethy1-amino)-titanium, -zirconium, or -hafnium interact with nickel, iron, andmolybdenum carbonyls to give 1 : 2 adducts of the type Ti(NMe2),,2Ni(C0),.34The reaction of tetraphenylcyclotetraphosphine and arsine with nickel, iron,chromium, molybdenum, and tungsten carbonyl have been reported.35With molybdenum and tungsten ring expansion occurs to give the (PhP),ring system.Terpyridyl (terpy) reacts as a bidentate with chromium,molybdenum, and tungsten carbonyl to give M(CO),(terpy) ;36 the potentialtridentate arsine, tris-l,l,l-(dimethylarsinomethy1)ethane (vr-trias) alsobehaves as a bidentate in the compounds [W(CO),(v-trias)] and[Re( CO) 3C1( v-trias)] .37 A series of bisphosphinetricarbonylmanganese anionshave been prepared; their interaction with alkyl and acyl halides and thecorresponding fluorinated derivatives have been in~estigated.~S Thephosphine derivative of rhenium carbonyl, Re( CO) ,(PPh,) ,, is monomeric,paramagnetic and the zero dipole moment indicates a trans-bipyramidalstructure whereas the corresponding diethylphenylphosphine compound,[Re(CO),(PEt,Ph),],, is diamagnetic in the solid and presumably dimeric,but is paramagnetic in solution.39 Reaction of iron carbonyl with n-butyl-amine or piperidine gives complexes of the type Ph-NH*CO*Fe(C0),.4°The complex Fe(CO),(PPh,), has been obtained from Fe(CO),(PPh3),Br2with sodium amalgam.41 The infrared spectrum and dipole moment indicate&-equatorial positions for the carbonyl groups.The preparation of theruthenium carbonyl phosphine or arsine compounds Ru(C0) ,( MPh,) ,(M = P, As) is reported; oxidation of the phosphine compound gives aseries of octahedral complexes, Ru(CO),[P(Ph),],XP (X = Y = I, Br,CF,*CO,; X = H; Y = C1, Br).42 The photochemical reaction of thebridged dimethylphosphino-carbonyls of iron and molybdenum withphosphines has been reported.43 The details of the structure of the oxygencarrier described last year, IrO ,C1( CO)( PPh,) , have been given." Thedipole moments of the compounds NiCO[PhP( o-C,H,-PEt,) ,] and31 M.Ziegler, H. Haas, and R. K. Sheline, Chem. Ber., 1965, 98, 2454.3a W. Strohmeier, and P. Hartmann, 2. Natwfwsch., 1965, 20b, 613.33 C. H. Bamford, J. Hobbs, and R. P. Wayne, Chem. Comm., 1965, 469; C. H.Bamford, G. C. Eastmond, and K. Hargreaves, Nature, 1965, 205, 385; C. H. Barnford,G. C. Eastmond, and W. R. Maltman, Trans. Faraday Soc., 1965, 61, 267.34D. C. Bradley, J. Charalambous, and S. Jain, Chem. and Ind., 1965, 1730.35 H. G. Ang, J. S . Shannon, and B.0. West, Chem. Comm., 1965, 10; G. W. A.36M. C. Ganorkar and M. H. B. Stiddard, J . Chem. Soc., 1965, 5346.37 R. S. Nyholm, M. R. Snow, and M. H. B. Stiddard, J . Chem. SOC., 1965, 6564.38 W. Hieber, J. Muschi, and H. Duchatsch, Chem. Ber., 1966,98,3924; W. Hieber,39F. Nyman, Chern. and Ind., 1966, 604.40 W. F. Edgell, M. T. Yang, B. J. Bulkin, R. Bayer, and N. Koizumi, J. Amer.4 1 W. Hieber and J. Muschi, Chem. Ber., 1965, 98, 3931.43 J. P. Collman and W. R. Roper, J . Amer. Chem. Soc., 1965, 87, 4008.D. T. Thompson, J . Organometallio Chem., 1965, 4, 74.44 S. J. La Placa and J. A. Ibers, J . Amer. Chem. SOC., 1965, 87, 2581.Fowles and D. K. Jenkins, ibid., p. 61.M. Hofler, and J. Muschi, ibid., p. 311.Chem. SOC., 1965, 87, 3080KOEL AND LEWIS TRAWSITIOX-METAL CARBONYLS 191NiCO[MeC(CH,*PPh,),] have been reporfed 45 and discussed in terms of theNi-C bond order.The nickel complexes (1) and (2; R = Et, Ph) of bis-(phosphin0)-o-carboranes have been prepared.48 New preparative methods('1 (2)for mixed carbonyl fluoro-phosphine adducts of nickel, iron, manganese,chromium, molybdenum, and tungsten have been reported.47 All the pos-sible compounds and isomers of the series M O ( C O ) ~ ( P F ~ ) ~ - ~ (x = 0-5) havebeen prepared and isolated.48Nphm Derivatives.-Interaction of 1,4-dithian(dt) with molybdenumand tungsten carbonyls give dimeric species [M(CO),dt], (M = Mo, W).49Reaction of sulphur-tin complexes, e.g. (MeS) ,SnMe2, with manganese andrhenium carbony150 provides a new method for forming sulphur-metalcarbonyl complexes, and provides a new trinuclear metal cluster :XM(CO), + (MeS),SnMe ---+ [MeS*M(CO),], (M = Mn, Re; X = Br, CI).Similar compounds may be prepared for rhenium and the metalcarbonyl halide.The interaction of penfafluorophenyl mercaptan andrhenium hydride has been investigated.51 Thiophentricarbonylchromium,C4H,SCr(CO),, has been formulated as a n-complex on the basis of X-raydata.52 The structure of [SFe(C0)J2 has been determined and contains adisulphide group symmetrically bonded to two tricarbonyl iron fragmentscontaining a '' bent " iron-iron bond.53 A related compound, [S,Fe,(CO)J,has been shown t o be the product of reaction of 2-mercaptobenzothiazoleand iron carbonyl.54 Derivatives of substituted lY4-dithiins and ironcarbonyl have been isolated.55 With 2,5-diphenyl-l ,Q-dithiin the productis formulated as (3).Ph H' C = c'4 5 J.Chatt and F. A. Hart, J . Chem. SOC., 1965, 812.O6 F. Rohrscheid and R. H. Holm. J . Organonzetallic Chem., 1965, 4, 335.47 J. G. Verka.de, R. 33. McCarley, D. G. Hendricker, and R. W. King, .ln.org. Chem.,1965, 4, 228: T. k c k and K. Baur, Chem. Ber., 1965, 98, 3070: A. Loutellier andM. Bigergne, BuU. SOC. chim. France, 1965, 3186: A. S. Basenally, 3%. S. Nyholm,D. J. Parker, Ed. B. Stiddard, 0. J. R. Hodder, and H. M. Powell, Chern. and Ind.,1965, 2097.48R. J. Clark and R. I. Wobermaa, Inorg. Chem., 1965, 4, 1771.OS H. C. E. McFarlane and W. McParlane, J. Inorg. Nuclear Chem., 1965, 27, 1059.50 E.W. Abel, €3. C . Crosse, and D. B. Brady, J. Amer. Chem. Soc., 1965, 87, 4397.alA. G. Osborne and F. G. A. Stone, Chem. Corn., 1965, 361.a z M . F. Bailey and L. F. Dahl, Inorg. Ohem., 1965, 4, 1306.5s C. H. Wei and L. F. Dahl, Inmg. C h i . , 1965, 4, 1.54 R. Havlin and G. R. Knox, J. Organometallic Chern., 1965, 4, 247.5 5 C. W. Bird and E. M. Hollins, J . Orp~aometallic Chern., 1966, 4, 245192 INORGANIC CHEMISTRYHalogen Derivatives.-Oxidation of the anions [M(CO)I],- to [M(C0)413J-(M = Mo, W), reported last year 56 has been extended to yield the seven-co-ordinated mixed halogeno-compounds [M(CO),XY,]- (M = Mo, W;X = Br, I; Y = Br, I); the stability of the anions is very dependent onthe cation used.57 Oxidation of a series of tridentate arsenic chelate com-plexes of molybdenum and tungsten carbonyls also leads to seven- co-ordinatecomplexes [M(CO),(trias)X]X and [M(CO),(trias)X,] [M = Mo, W;X = Br, I ; trias = methylbis(dimethylarsino-3-propyl)arsine, v.Trias =bis(o-dimethylarsinopheny1)methylarsine (TTAs)] .58 With the diphosphine,1,Z-bisdiphenylphosphinoethane (diphos) complexes, oxidation of the tetra-carbonyl derivatives [M( CO),( diphos)] yields similar seven-ca-ordinatespecies W(CO),(diphos)X,] (M = Mo, W; X = Br, I), but with theclicarbonyl complexes, [M(CO),(diphos) ,I, paramagnetic six-co-ordinatederivatives of molybdenum and tungsten(1) are obtained.59 Oxidation ofthe diphos complexes or the triphenylphosphine-substituted carbonyls withexcess of halogen leads to phosphine oxide derivatives of molybdenum andtungsten(v and VI).~* The use of antimony pentachloride as a controlledchlorinating agent for arene carbonyls of tungsten has been established, togive [( arene)W( CO),C1]SbC16.61Manganese carbonyl bromide and iodide interact with diphos to yield[Mn(CO),(diphos)X] (X = Br, I) but with the chloride the cation[Mn(CO),(diphos) is obtainede6, The reaction of thiocyanogen chloridewith sodium manganese carbonyl gives [Mn(CO),CNS].The compound issulphur-bonded in the solid state, and nitrogen-bonded in acetonitrile.63In chlorinated solvents an equilibrium exists between the two forms ofbonding. Bromination of triphenylphosphine tetracarbonyl compounds ofmanganese and rhenium give mixtures of cis- and trans-M(CO),(PPh,)(Br) .64Oxidation of Re( CO)( diars) 2X (diars = o-phenylenebisdimethylarsine) givesthe seven-co-ordinate compounds of rhenium(m), [Re(CO)(diars)X,]Y(X = Br, I; Y = Br,, I,, ClOJ.65 Five-co-ordinate derivatives of cobalt(r),Co(CO),LX [X = C1, I; L = P(Ph,), P(OPh),; X = Br, L = PPh,], havebeen obtained by oxidation of the sodium salt Na [Co( CO) ,L] with phosphorusoxychloride, perfluoromethyl iodide, or N - bromosuccinimide. The chlorideand bromides readily decompose to give Co(CO),L2X derivatives. Thecompounds Co(CO),L2C1 react with carbon monoxide in the presence ofaluminium chloride to give [Co(CO) ,L2][A1Cl4].The acyl derivativesC,H,COCo(CO),L (L = PPh,, P(OPh),) have also been described.66 Deriva-5 6 D. Nicholls, Ann.Reports, 1964, 61, 170.5 7 M. C. Ganorkar and M. H. B. Stiddard, J . Chem. Soc., 1965, 3494.5~ C. D. Cook, R. S. Nyholrn, andM. L. Tobe,J. Chem.Soc., 1965,4194; R. S . Nyholm,M. R. Snow, and M. H. B. Stiddard, ibid., p. 6570.69 J. Lewis and R. Whyman, Chem. Comm., 1965, 159; J . Chem. Soc., 1965,5486.J. Lewis and R. Whyman, J . Chem. Soc., 1965, 6027.61M. R. Snow and M. H. B. Stiddard, Chem. Comm., 1965, 580.62A. G. Osborne and M. H. B. Stiddard, J . Chem. SOC., 1965, 700.63 M. F. Farona and A. Wojcicki, Inorg. Chem., 1965, 4, 857.64 P. W. Jolly and F. G. A. Stone, J . Chem. SOC., 1965, 5259.6 5 W. J. Kirkham, A. G. Osborne, R. S. Nyholm, and M. H. B. Stiddard, J . Chem.66 W. Hieber and H. Duchatsch, Chern. Ber., 1965, 98, 1744.SOC., 1965, 550KOHL AND LEWIS: TRANSITION-METAL CARBONYLS 193tives of C,H,Co(CO)X, (X = C1, Br, I) have been prepared.s7 The phosphinecarbonyl chlorides of rhodium have been prepared from the rhodium(1n)chloride with phosphine in a series of non-alcoholic oxygen-containingsolvents and by decarbonylation of aldehydes with RhC1( PPh3)3.68 A seriesof bridged compounds [Rh(CO),X], (X = carbonyl, NO3, CNS, S,O,) andmononuclear compounds RhX(am)(CO), (am = pyridine, NH,, C6H,NH2,MeC6H5NH2, cc-picoline, bipyridyl) have been ~repared.6~ The preparationof anions [Rh(CO),X,]- (X = C1, Br, I), [Rh(CO),X,]- (X = C1, Br, I),[R8h,(CO)2X,]2- (X = Br, I), and [Rh(CO)I,]- has been reported.70 A newcarbonyl halide Pd2( CO) ,C1 has been isolated ; the complex is diarnagneti~.~~Miscellaneous.-Silicon-metal bonded derivatives have been isolated byreaction of Ir(PPh,),COCl with substituted silicon hydrides 7, and cobalt-silicon bonded complexes are postulated as intermediates in the hydrosilationof olefins catalysed by cobalt octacarbonyl.73 The silicon cobalt carbonylderivatives R’R,S~CO(CO)~ (R’ = R = C1, Et, Ph, H ; R’ = Ph; R = C1) havebeen prepared.74 The formation of carbonyl-cyanide ions [Ni(CN)(CO),]-and [Fe( CO),CN]- occurs in the reaction of substituted silylsodamides withmetal ~arbonyls,~~ e.g., Fe(CO), + NaN(SiR,), = Na[Fe(CO)&’N] + O(SiR,),.Hydrides .-T he structure of h ydrido c hloro bisdip hen y le t h y lp ho s phine -platinum(n) has been determined,Y6 and it is inferred that the hydrogenoccupies a co-ordinate position in the phosphorus-chlorine plane trans tothe chloride ion.The platinum-chlorine distance is longer than calculatedfrom the sum of the ionic radii rules and this is associated with the hightrans-directing effect of the hydride ion. Interaction of palladium and theortho-hydrogens of the phenyl groups of dimethylphenylphosphine is indicatedin the X-ray structure 77 of the yellow isomer of di-iodobis(dimethylpheny1-phosphine)palladium( II) . A similar interaction appears also in the complexdichlorotris( triphenylphosphine)ruthenjum( 11) . 78 A related situation occursin the system obtained by reduction of truns-[RuCI,(PP) J, wherePP = Me2P*CH,*CH,PMe2, with arene negative ions ; for the naphthaleneion a complex cis-[Ru(Cl,H8)(PP),~ is obtained.This complex involves atautomeric equilibrium between the structures [Ru(C,,H,)(PP),] andcis-[RuH(2-CI,H,)(PP),]. Pyrolysis of the compound gives naphthaleneand the complex [Ru(PP),]; the latter provides an example of a new classof compound in which hydride transfer takes place from the alkyl sidechain of the phosphine to the metal ion to provide a hydride and a tauto-meric system similar to that postulated for the naphthalene-phosphineG 7 R. F. Heck, Inorg. Chem., 1965, 4, 855.68 A. Rusina and A. A. VlEek, Nature, 1965, 206, 295; J. Tsuji and K. Ohno,6g D. N. Lawson and G. Wilkinson, J . Chem. Soc., 1965, 1900.70 L. M. Vallarino, Inorg. Chem., 1965, 4, 161.71 E. 0. Fischer and A. Vogler, J . Organometallic Chem., 1965, 3, 161.A. J.Chalk and J. F. Harrod, J . Amer. Chem. SOC., 1965, 87, 16.7s J. F. Harrod and A. J. Chalk, J . Amer. Chem. SOC., 1965, 87, 1133.v 4 B. J. Aylett and J. M. Campbell, Chem. Comm., 1965, 217.7aU. Wannagat and H. Seyffert, dngew. Chem., 1965, 77, 457.R. Eisenberg and J. A. Ibers, Inorg. Chem., 1965, 4, 773.7 7 N. A. Bailey, J. M. Jenkins, R. Mason, and B. L. Sham, Chem. Comm., 1965,7* S. J. La Placa and J. A. Ibers, Inorg. Chem., 1965, 4, 778.Tetrahedron Letters, 1965, 3969.237194 INORGANIC CHEMISTRYcomple~.~O A most important development has been the first synthesisof a series of hydrido-trifluorophoraphine metal complexes, HM(PF,)(M = Co, Rh, Ir) and a hydrido-carbonyl complex, HCo(PF3),C0.79@The X-ray structure of the compound HMn3(CO)lo(BH,)2 is the first ofa polyborane-transition-metal carbonyl.The BH, groups are joined by aB-B bond and all three hydrogens of the BH, groups are bonded to man-ganese atoms; the unique hydrogen in the structure is considered to bebonded symmetrically between two manganese atoms.80 A similar typeof hydrogen-bonding system is considered to occur in the molecule[(C5H5),Mo2H(PMe,)(CO),] ; from the X-ray structure it is considered thatthe hydrogen is bonded between the two molybdenum atoms to give it a“ symmetrical, bent, three-centre metal-hydrogen-metal bond.”81 In theRaman spectra of the hydrido- and deuterio-rhenium tetracarbonyl trimer[Re(CO),H], a weak band in the Raman spectrum of the hydride, at1600 cm.-l, moves to 787 cm.-l in the deuteride.82 This is assigned to aRe-H-Re bridging vibration.The infrared and n.m.r. spectra of the com-plexes [HM,(CO),,]- (M = Cr, Mo, W) indicate the proton is equivalentlybonded to both metal ions in a bridged s t r ~ c t u r e . ~ ~The reduction of [CoBr,(diphos),] with sodium borohydride gives thehydride [CoH(diphos),J ; alternative reduction of the compound with potas-sium hydroxide-aqueous ethyl alcohol solutions in an atmosphere of nitrogengives the cobalt(0) compound [Co(diphos),]. This will absorb hydrogen a troom temperature to give the hydride.84 Reduction of the bis(dimethy1-glyoximato)cobalt(m) compounds, CoX(dmg),B (X = halogen; B = pyri-dine, tri-n-butylphosphine ; dmg = the anion of dimethylglyoxirne), withsodium borohydride gives the hydride HCo( dmg) 2B.Interaction of thehydride with the triphenyl-Group IV halides give metal-metal bondedspecies, with liberation of hydrogen halide. 85 Reaction of the correspondinghalogenoiridous acid with cyclo-octa- 1,5-diene gives the halogen- bridgeddimeric hydride [IrHX,(dien)], (X = C1, Br, I). Reaction of these com-plexes with sodium carbonate-methyl alcohol gives the methoxy- bridgedcompounds [Ir( OMe)(diene)]2;86 this may be reconverted into the hydrido-halogeno-complex with halogen acids. The proton n.m.r. of a series ofphosphineplatinum hydrides has been reported.87 The platinum-hydrogencoupling constants are -1200 c./sec. whilst the phosphorus-hydrogencoupling constants axe -15 c./sec.Nitrosgls.-The e.8.r.spectrum of the ions [Cr(NO)(H,0),]2+,7 9 J. Chatt and J. M. Davidson, J. Chem. SOC., 1965, 843.700 T. Kruck, W. Lang, and A. Engelmann, Angew. Chem., 1965, 77,132: T. Kruckand W. Lang, Chern. Ber., 1965, 98, 3060: T. Kruck, W. Lang, and N. Dorner, 2.Natwforsch., 1965, 20b, 705: T. Kruck and W. Lang, Angew. Chm., 1965, 77,860.8 0 H. D. Kaesz, W. Fellmam, G. R. Wilkes, and L. F. Dahl, J . A w r . Chern. SOC.,1965, 87, 2753.8lR. J. Doedens and L. F. Dahl, J . Arner. Chern. SOC., 1965, 87, 2576.8% J. M. Smith, W. Fellmann, and L. H. Jones, Inorg. Chem., 1965, 4, 1361.83 U. Anders and W. A. G. Graham. Chem. Comm., 1965, 499.8 4 A. Sacco and M. Rossi, Chem. Comm., 1965, 602.86 G. N. Schrauzer and G. Kratel, Angew. Chem., 1965, 77, 130.8 6 s .D. Robinson and B. L. Shaw, J . Chem. SOC., 1965, 4997.8 7 J. Powell and B. L. Shaw, J . Chem. SOC., 1965, 3879KOHL AND LEWIS: TRANSITION-METAL CARBONYLS 195[Cr(NO)(NH,) J2+, [Mn(CN)5N0 J2-, [Pe( CN)5NO]3-, and [Cr(CN)5N0]3-,88as well as the ultraviolet and visible spectra of [Fe(CN)5N0]2-,89 have beendetermined and interpreted in terms of mo1ecula.r orbital theory. The anglebetween equivalent NO and CO groups in complexes has been correlatedwith the intensity of the symmetrical and asymmetrical vibrations of thegroups.90 The infrared criterion for determining the mode of bonding ofthe NO group in nitrosyls has been questioned, in particular the rangeappropriate to the NO- bonding scheme has been discu~sed.~~ The electronicspectra of the complexes [CoX*NOL,]+ (L = diars; X = Br, C1, I, CNS;L = en; X = Cl, Br, I, NO,) are readily assigned on the basis of CoIU,with NO- bonding, yet the infrared frequency of the NO groups are-1600 cm.4.92 Nitrosylpentacarbonylvanadium reacts with tetraphenyl-diphosphine to give binuclear complexes maintaining the diphosphine unit(NO)(CO>,*V*PPh,*PPh2~V*(CO),(NO). The corresponding cobalt complexon heating rearranges to the phosphino-bridged complexes(NO)( CO) ,Co*Ph,P-PPh,*Co( CO) ,NO -+ [Co( CO)(NO)PPh,] 2.93Vanadium tetrachloride reacts with nitric oxide t c ~ give a polymeric chlorinebridge nitrosyl [(NO) 3VC12]n.94 The polymeric chloronitrosylmolybdenum[Mo(NO) zC12]n reacts with the maleonitriledithiolate ion (MNT) to give theanionic species ~O(NO),(MNT),]~-.~~ A study of the e.s.r.spectrum ofaqueous solutions of a variety of iron@) salts with nitric oxide has beenreported; the data indicate an equilibrium in the solutions between dia-magnetic and paramagnetic nitrosyl species.96 The nitrosyl-thiocyanatesof iron, cobalt, and nickel are formed by the reaction of the metal nitrosylhalide with potassium or silver thiocyanate; the reaction of the compoundswith tertiary organic phosphines, arsines, stibines, as well as phenanthrolineis rep~rted.~' Nitrosyl allyl iron compounds are formed by reaction ofallyl iron carbonyl halides, (allyl)Fe(CO),X (X = halogen)? with nitricoxide, or the nitrosyl carbonyl anion [Fe(CO),NO]- with allyl halides.Reaction of the complex (allyl)Fe( CO) ,(NO)a derivative formulated g8 as (4),NOwith triphenylphosphine(4)gives8B I.Bernal, S . 33. Robinson, L. S. Meriwether, and G. Willrinaon, Chem. Comm.,1965, 571; H. B Gray, P. T. Manoharan, J. Pearlman, and R. F. Riley, ibid., p. 62;P. T. Manoharan and H. B. Gray, ibid., p. 324; J. J. Fortman and R. G. Hayes, J . Chem.Phys, 1965, 43, 15; EI. A. Kuska and M. T. Rogers, &d., 1965, 42, 3034; D. A. C.McNeil, J. B. Raynor, and M. C. R. Symons, J . Chem. SOC., 1965, 410.89 P. T. Manoharan and H. B. Gray, J . Amer. Ghem. SOC., 1965, 87, 3340.91 P. Gans, Chem. Comm., 1965, 144.92 R. D. Feltham and R. S. Nyholm, Inorg. Chem., 1965, 4, 1334.98 W. Hieber and R. Kummer, 2. Naturforsch., 1965, 20b, 271.94 W. Beck, K. Lottes, and K.Schmidtner, Angew. Chem., 1965, 77, 134.96 J. Locke and J. A. McCleverty, Chem. Comm., 1965, 102.96 C. C. McDonald, W. D. Phillips, and H.F. Mower,J. Amer. Chem. Soc., 1965,8'9,3319.I~'W. Hieber, I. Bauer, and H. Neurnair, 2. anorg. Chem., 1965, 335, 260. ** R. Bruce, F. M. Chaudhary, G. R. Knox, and P. L. Pauson, 2. Naturforsch.,W. Beck, A. Melnikoff, and R. Stahl, Angew. Chem., 1965, 77, 719.1965, 20b, 73; M. D. Murdoch, ibid., p. 279196 INORGANIC CHEMISTRYThe nitrosyltricarbonyliron anion reacts with fluorinated carboxylic acidsin the presence of triphenylphosphine to give RfCOFe( CO)(NO)( PPh,),(Rf = CF,, C2F6).99 The magnetic properties of nitrosyliron SchiE-baseshave been investigated ; the salic ylaldehyde-ethylenediamineiron ni tros ylcomplex shows a change in the magnetic properties from three unpairedelectrons a t room temperature to one unpaired electron at 180" K .~ O O AnX-ray structure of the black nitrosylpentamminecobalt dichloride,[Co(NH,),NO]CI,, indicates a linear Co-N-0 system, with a long Co-N bondfor the ammonia co-ordinated tram to the nitrosyl group.lO1 cis- and truns-Isomers have been detected for the binuclear complexes (5)X/ \(M = Co, Ni; X = halogen; L = SR, PR,, AsR,),lo2 in the complexesCo(NO),L(CNS)Ni(NO),L,CNS the infrared spectra indicate the bonding isthrough the nitrogen of the CNS group. Bridging thiocyanate groups arepresent in the polymeric nitrosyl complexes [M(NO),CNS], (M = Fe, Co,[Ni(NO)(CNS) 1% ; [Ni( NO)L,( CNS)],) .97Transition-Metal Carbons1 Complexes Containing Metal-Metal Bonds.-Continued interest has been maintained in this series of compounds; thefield has been reviewed.lM Mixed carbonyl-carbonylcyclopentadienylcomplexes C,H,M(CO),-M'(CO), (M = Mo, W; M' = Re, Mn) have beenreported.104 Using the triarsine ligands, v.trias and TTAs, the followingcomplexes have been prepared.[(trias)M-Mn(CO),], [(trias)M],Fe(CO),,[(trias)M-Co(CO),] (M = Cu, Ag).lo5 The X-ray structures of the com-plexes [(TTAs)Cu-Mn(CO),], Ph,Ge*Mn(CO),, and Ph,PAuCo(CO), arereported.lW The manganese complexes are octahedral, whilst the cobaltcomplex is trigonal bipyramidal. In the copper complex the four carbonylscis to the copper are displaced from the equatorial plane towards thecopper atom, similarly in triphenylphosphinegold-cobalt tetracarbonylthe thee CO groups are displaced out of the equatorial plane towardsthe gold atom.The preparation and infrared spectra of a series ofphosphine, arsine, and stibine complexes (L or L') of the gold-manganesecarbonyl system, LAuMn( CO), and LAuMn(CO),L' have been discussed.lo7Complexes with rnercury-metal bonds have been isolated with tungsten99 W. Hieber, W. Klingsliirn, and W. Beck, Chem. Ber., 1965, 98, 307.100 A. Earnshrzw, E. A. King, and L. F. Larkworthy, Chem. Comm., 1965, 180.101 D. Hall and A. A. Taggart, J . Chem. SOC., 1965, 1359; D. Dale and D. Crowfoot102 W. Beck and K. Lottes, 2. anorg. Chem., 1965, 335, 258.lo3 J. Lewis, Pure Appl. Chem., 1965, 10, 11.lo* A. N. Nesmeyanov, K.N. Ainsimov, N. E. Kolobova, and A. S. Beschastnov,Doklady Akad. Nuuk S.S.S.R., 1964, 159, lf84.*lo5 A. S. Kasenally, R. S. Nyholm, and M. H. B. Stiddard, J . Chem. SOC., 1965,5343.106 B. T. Kilbourn, T. L. Blundell, and H. M. Powell, Chem. Comm., 1965, 444.lo7 A. S. Kasenally, J. Lewis, A. R. Manning, J. R. Miller, R. S . Nyholm, andHodgkin, ibid., p. 1364.M. H. B. Stiddard, J. Chenz. SOC., 1965, 3407.* Ref. to the English edition of Russian journalKOHL AND LEWIS : TRANSITION-METAL CARBONYLS 197[W(CO),(bipy)(HgCl),] lo8 and iridium [Ph,P],(CO)ClYIr-HgY (Y = C1, Br,I, OAc, CN, SCN).lOg The infrared spectra of the compounds (XHg),Fe(CO),(X = C1, Br, I) have been determined in the low-frequency region and theHg-Fe stretching frequency assigned.l1° Indium-cobalt complexes havebeen prepared by an insertion of indium bromide between the cobalt atomsof cobalt carbonyl.111C , W \ , co(co)4/ I nTHP ~ 1nBr + CO,(CO)~Br ’ ‘co(co)4The compound loses tetrahydrofuran (THF) under vacuum t o give thebromide-bridged complex [Co( CO),],In.Br,In[Co( CO),].Rhenium-metalbonds are formed by the interaction of the rhenium pentacarbonyl anionwith chlorophenyl derivatives of tin, lead, antimony, and bismuth. Partialbromination of the complex Ph,SnRe(CO), with two molecules of brominegives the dibromophenyltin-rhenium pentacarbonyl, Br,PhSnRe( CO) , ;reaction of this with a further two molecules of the pentacarbonylrheniumanion yields the complex PhSn[Re(CO) ,],.112 Variations on this type ofreaction have produced systems with more than one type of metal-metalbond; the following complexes : [(C,H,)F~(CO),],S~[MO(C~H~)(CO)~]~ 113 and[(CO),Mn]SriMe,[W(CO),(C,H,)J 114 have been prepared by this technique.Complexes of organo-tin and -lead with iron and cobalt carbonyl have beendescribed.l15 Reaction of n-butyltin tricliloride with cobalt octacarbonylgives the complex BU~S~[CO(CO),],.~~~Organometallic Compounds of the Transition Metalsa-Bonded Organometallic Compounds.-The first stable allrylzirconiumcompounds have been prepared by the reaction 117(C,H,),ZrCI-O-ZrCl(CjH,), + 2Mc,A1+ 2(C,H,),ZrClMe + Me,AlOAlMe,The cyclopentadienylzirconium chloro-oxy-compound also reacts withlithium aryls with replacement of the chlorine to give aryl-zirconium deriva-tives.118 Methyl derivatives of chromium-(In) and -(II) have been isolatedas the dioxan adducts Li,Cr(CH3),,3C,H,O, and Li,Cr(CH,)4,2C4~80, fromthe reaction of methyl-lithium with anhydrous chromium-(rc) and - (111)chloride.The chromium(n1) compound is paramagnetic (per -- 3.75 B.M.),lo* M. C. Ganorkar and M. H. 13. Stiddard, Chem. Comm., 1965, 22.Io9 R. S. Nyholm and K. Vrieze, J. Chem. SOC., 1965, 5337.I1O D. M. Adams, D. J. Cook, and R. D. W. Kemmitt, Nature, 1965, 205, 589.l l a A. N. Nesmeyanov, K. N. Anisimov, N. E. Kolobova, and V. N. Khandozhko,113 S. V. Dighe and M. Orchin, J. Amer. Chem. SOC., 1965, 87, 1146.11* H. R. H. Patil and W. A. G. Graham, J . Arner. Chem. SOC., 1965, 8’9, 673.l15F. Hein and W.Jehn, Anrzalen, 1965, 684, 4 .116 S. D. Ibekwe and AX. J. Newlands, Chem. Comm., 1965, 114.11’ J. R. Surtees, Chenz. Comm., 1965, 567.118 E M Braimina, G. G. Droryantseva, and R. Kh. Freidlina, Doklady Akad. NaukD. J. Patmore and W. A. G. Graham, Chern. Conzm.. 1965, 591.Doklady Akad. Nauk S.S.S.R., 1964, 156, 502.”S.S.S.R., 1964, 156, 1375.’* Ref. to the English edition of Russian journal198 INORGANIC OEEMISTRYbut the chromium(rr) compound is diamagnetic and dimerio in benzene.119A corresponding 1 : 4 butane compound has been prepared with chro-dUm(III), Lj,Cr(C,H8),,2.5C,H802 ( p , ~ = 3-9 B.M.) and a diamagnetic1 : 5 pentane adduct for chromium(n), Li2Cr(C5Hl,),,LiBr,3Et20.120 Inter-action of 2-, 3-, or 4-bromomethylpyridine salts with chromium(rr) salts givesstable a-bonded compounds of chromium of the type [2-Py-CH,*Cr(H20),]3+ ;using 2-( bromomethy1)pyridine bromide yields the first compound containinga, secondary carbon-chromium bond.121 The benzylchromium complexPhCH2-Cr(C6H6N) has been isolated by treating benzyl chloride withdichlorobispyridinechomium(n) in pyridine at Ooc.l22 The interaction ofa-bonded organochromium compounds with carbon monoxide and ketoneshas been investigated.12, Vinylcyclopentadienyliron dicarbonyl has beenprepared by reacting cyclopentadienyliron dicarbonyl chloride with vinyl-magnesium bromide.124 a-Bonded organocyanocobalt(n) complexes may beprepared by interaction of the cobalt cyanohydride ion, [Co(CN),HI3-, withan activated olefin or cobalt pentacyanide ion [co(cN),]3- with organichalides.125 Previous attempts to prepare alkyl deriva-tives of CoIII porphyrins lead to reduction to CoII.The methyl and ethyl Coin derivatives of aetio-porphyrin may be prepared by reacting the bro-mide complex with alkylmagnesium halide.126The trisacetylacetonatoplatinum(n) anion, whichcontains two carbon-bonded acetylacetone groupsand one bidentate oxygen-bonded acetylacetonegroup, reacts with acid to give a rnetal-diene complex (6) of the compound.12'Carbon-metal bonding occurs in platinum and palladium in the metal-azobenzene adducts (7) ,l2*CH3(6)H3C $310,CH3q N"N/ MI, C!'CIN119 E.Kurras and J. Otto, J . OrganometaZGc Chem., 1965, 4, 114.lao E. Kurras and J.Otto, J. Organometallic Chem., 1965, 3, 479.lal R. G. Coombes, M. 0. Johnson, M. L. Tobe, N. Winterton, and Lai-Yong Wong,la2 R. P. A. Sneeden and H. P. Throndsen, Chem. Corn., 1965, 509.lea R. P. A. Sneeden, T. F. Burger, and H. M. Zeiss, J . Organometallic Chem., 1965,124 M. L. H. Green, M. Ishaq, and T. Mole, 2. Naturforach., 1965, 20b, 698.126 J. Kwiatek and J. K. Seyler, J . Organom,etaEZic Chem., 1965, 3, 421.lea D. Dolphin and A. W. Johnson, Chem. Comm., 1965, 494.12' D. Gibson, C. Oldham, J. Lewis, D. Lawton, R. Mason, and G. B. Robertson,128 A. C. Cope and R. W. Siekman, J . Amer. C h . Soc., 1965, 87, 3272.Chem. Comm., 1965, 251.4, 397.Nature, 1965, 208, 680KOHL AND LEWIS: TRANSITION-METAL CARBONYLS 199(M = Pt, Pd). A similar type of interaction has been postulated in someiron derivatives.129 Arylazoplatinum compounds formed by reaction of adiazonium salt with platinum hydride complex decompose to give aryl-platinum complexes.130[PhNd?]BF, + HPt(PEt,),Cl+ [PhN =NH-Pt(PEt3),C1]+BFI- -+ PhPf(PEt,),Cl.The preparation and the i.r.and n.m.r. spectra of triethylplatinum chloridehave been reported.131 The X-ray structure of p-ethylenediaminebis-[trimethyl( acetylacetonafo)platinum(Iv) J has been reported ; the acetylace-tone is oxygen-bonded to the metal and the two platburn groups areconnected through a bridging ethylenediamine The nature ofethylzinc iodide solutions has been in~estigated,~~~ and new preparativemethods for RHgC1 and R,Hg (R = Me; CH, = CH-, Ph) from NH,(RSiF,)and mercuric chloride discussed.134 The preparation of the complexesPhHgL (L = CCl,, CBr,, CClBr,, CC1,Br) has been reported.13jFluorke-Contahing a-carbon Complexes.-The infrared spectra in thecarbonyl region for some fluoro-organo-maganese and -rhenium penta-carbonyl adducts have been interpreted in terms of reduction of thesymmetry around the metal ion from C,, by the ligand gr0up.13~ TheX-ray structure of iodocarbonylcyclopenta~enylpentafluoroethylrho~ium,C5H,Rh(CO)C2F51, has been determined and the Rh-C bond length fromthe pentafluoromethyl group has been interpreted as indicating metal-carbon double bonding between the metal and pentafluoroethyl group.137Metal-to- carbon double bonding in perfluoroalkyl compounds has also beeninferred from the infrared spectra of perfluoromethylmanganese penta-carb0ny1.l~~ The synthesis of the pentafluorophenylcyclopentadienyl com-pounds of zirconium and titanium, (C,F,),M(C,H,), from pentafluorophenyl-lithium has been reported.13@ This reagent and pentafluorophenylmagnesiumbromide have been used to prepare phosphine-halide complexes of platinum-(II) containing the pentafluorophenyl group.140 The interaction of carbonylperfluoroalkylcyclopentadienylcobalt iodide with a variety of ligands suchas triphenylphosphine, in the presence of silver perchlorate, has been shamto give complexes of the type [C,H,CO(CO)(PP~,)C~I?,]C~O,.~~~A ready method for the formation of a-bonded fluorinated organometalliccompounds is from the fluorinated olefins and a metal hydride complex.129 M.M. Bagga, P. L. Pauson, F. J. Preston, and R. I. Reed, Chem. Comm., 1965,130 G. W. Parshall, J . Amer. Chew,. SOC., 1965, 8’9, 2133.l31 S. F. A. Kettle, J . Chem. SOC., 1965, 5737, 6664.132A. Robson and M. R. Truter, J . Chem. Xoc., 1965, 630.133M. H. Abraham and P. H. Rolfe, Chem. Comm., 1965, 325.13* R. Miiller and C. Dathe, Chem. Ber., 1966, 98, 235.135 D. Seyferth and J. M. Burlitch, J . Organometallic Chm., 1965, 4, 127.136 J. B. Wjlford and F, G. A. Stone, Inorg. Chem., 1965, 4, 389.137 M. R. Churchill, Inorg. Chena., 1965, 4, 1734.138 F. A. Cotton and J. A. McCleverty, J . OrganometaUic Chem., 1965, 4, 490.13s C. Tamborski, E. 5. Soloski, and S . M. Dee., J . OrganornetalZic Chern., 1966,I4OD.T. Rosevear and F. G. A. Stone, J . Chem. SOC., 1965, 5275.141 P. hl. Treichel and G. Werber, Inorg. Chem., 1965, 4, 1098.543.4, 446200 INORGANIC CHEMISTRYReaction of an olefin with the hydrocarbonyls of manganese, rhenium,cobalt, and dicarbonylcyclopentadienyliron hydride, and hydrides of theplatinum-phosphine-halide systems, have been shown to yield 0- bonded~omp1exes.l~~ An insertion of tetrafluoroethylene in manganese-tin bondsto give M~,SIYCF,*CF,*M~(CO)~ has been shown to occur.143 With tri-fluoroethylene the corresponding reaction did not occur and a o-bondedfluoro-olefin was produced, CHF = CF*Mn(C0),.144 This class of compoundis also prepared by reaction of fluorinated olefins with the metal carbonylanions of rhenium and manganese, the dicarbonylcyclopentadienylironanion a.nd tetra carbon y ltrip hen ylp hos phinemang anese anion.145 With per -fluorocyclobutene the following reaction occurs :corresponding reactions have been established with perfluoro-propene-ethylene, -&clohe~ene.l~~ The anion Re(CO),- will replace fluorine inperfluorobenzene to give C,F,Re(CO),; the same compound may be obtainedby decarbonylation of C,F,CORe(CO> ,. The reaction of tetrafluoroethylenewith the cyanide and cyanohydride of cobalt yields the complexesK [ ( CN ) ,CoC zF & o ( CN ) 5], K [ C o ( CN ) , *CF ,* CF ,H 1, l4 The X-ray structureof the last compound has been reported and the metal-carbon distance ofthe fluorinated alkyl-metal system has been interpreted in terms of multiplebonding between the metal and the alkyl residue.147Caxboxylation Reactions.-The interaction of methyl- and phenyl-rnanganese pentacarbonyls with phosphines, arsines, or stibenes occurs withthe formation of acyl intermediates which may lose carbon monoxide togive the cis- and trans-isomers of the corresponding alkyl or aryl substitutedtetracarbonyl ~omp1ex.l~~ With methylmanganese pentacarbonyl this reac-tion has been extended to charged nucleophiles to give ions of the type[CH,COM~I(CO),I]-.~~~ Propionylcobalt tetracarbonyl and cobalt carbonylare formed from interaction of triethylaluminium with cobalt stearate inhexane under a carbon monoxide pressure.l50 Interaction of phenylmercuricnitrate with carbon monoxide (247 atm.) in benzene solution yields phenyl-mercuric benzoate.151The field of organo- Olefin-metal Complexes.-Nono-oZe$n complexes.142 J.B. Wilford, A. Forster, and F. G. A. Stone, J . Chem. SOC., 1965, 6519; J. B.Wilford and F. G. A. Stone, Inorg. Chem., 1965, 4, 93; M. L. H. Green and A. N. Stear,2. Naturforsch., 1965, gob, 812.143 H. C. Clark, J. H. Tsai, and W. S. Tsang, Chem. Comm., 1965, 171.14*H. C. Clark and J. H. Tsai, Chem. Comm., 1965, 111.145 P. TV. Jolly, M. I. Bruce, and F. G. A. Stone, J. Chem. Soc., 1965, 5830; P. W.Jolly and F. G. A. Stone, Chem. Cmm., 1965, 85.1 4 6 M . J. Mays and G. Wilkinson, J. Chem. Soc., 1965, 6629.14' R. Mason and D. R. Russell, Chem. Comm., 1965, 152.l4* W. D. Bannister, M. Green, and R. N. Haszeldine, Chern. Cornm., 1965, 54;C.S. Kmihanzel and P. K. Maples, J . Amer. Chem. Soc., 1965, 87, 5267.140 F. Calderazzo and K. Noack, J. Organometallic Chem., 1965, 4, 250.L50 P. Szabb and L. Markb, J . Organometallic Chem., 1965, 3, 364.151 L. R. Barlow and J. M. Davidson, Chem. and Ind., 1965, 165GKOHL AND LEWIS: TRANSXTION-METAL CARBONYLS 201metallic compounds of nickel has been reviewed.152 A series of olefin-arenechromium compounds have been reported, (arene)Cr(CO) tL, whereL = cycloheptene, cyclopentene, eth~1ene.l~~ The preparation of' bis-acraldehydemolybdenum dicarbonyl is described. The structure is con-sidered to be polymeric and as in the structure suggested for bisacraldehyde-nickel, bonding through both the olefinic and oxygen groups are envisaged.lj4The first tetrafluoroethylene complexes in which bonding occurs throughthe n-system have been established for rhodium;146, 155 the compIexes maybe prepared by displacement of ethylene from bis( ethylene)acetylacetonato-rhodium(1) or the bridged chlorobisethylenerhodium dimer.The reactionof chlorobis(triphenylphosphine)carbonyliridium(I) with tetrafluoroethylenegives (Ph,P) 21rC2F,(CO)C1.155 The tetrafluoroethylene is considered to bondin a similar manner to oxygen in the complex (Ph,P),Ir(CO)Cl*O,. Thecompound chlorobis( triphenylphosphine) (tetrafluoroethylene)rhodium( I) wasprepared from the tris( tripheny1phosphine)rhodium chloride by direct reac-tion with tetrafl~oroethylene.~~~ An n.m.r. study has established thatethylene exchanges rapidly with Zeise's salt, [K(C2H4PtCl3)H,O], and bis-ethyleneacetylacetonatorhodium(~) .156 New olefm complexes of platinum(I1)have been established with 4-vinylcyclohexene, and cyc10-ocfene.~~~ Theinfrared and n.m.r.spectra of a large number of olefin-silver complexeshave been studied.l58 Diphenylvinylphosphine is considered ta interactwith silver ion to bond by both the olefin group and phosphorusOlefin complexes of gold are reported from interaction of tetrachloroaurateion with cyclopentene, cyclohexene, cis-cyclo-octene, and trans-cyclo-decene.160 The various mechanisms for the isomerisation of olefins havebeen discussed.l61 The isomerisation of octenes by the iridium-phosphine-hyclride complexes, IrHC12( PEt,Ph), and IrH,( PPh,) 3, are considered toinvolve primary co-ordination to the Platinum-tin chloridecomplexes [PtC1,(SnCl,),-,.2- have been shown to catalyse double-bondmigration in higher olefins and a hydride intermediate is postulated in therea~ti0n.l~~ Ethylene-rhodium complexes are suggested as intermediatesin the rhodium chloride-catalysed dimerisation of ethylene to linearbuteiies .164Tris(tripheny1phosphine)rhodium chloride has been shown to be ahomogeneous hydrogenating system for olefins and a~ety1enes.l~~ A detailed152 C.N. Schrauzer, Adv. Organometallic Chem., 1965, 2, 2 .153 W. Strohmeier and H. Hellmann, Chem. Ber., 1965, 98, 1598.and F. J. Knoll, Inorg. Chem., 1965, 4, 1323.155 0. W. Parshall and R. Cramer, J . Amer. Chem. Soc., 1965, 87, 1392.lS6 R.Cramer, Inorg. Chem., 1965, 4, 445.15' E. Kuljian and H. Frye, 2. Naturforsch., 1965, 20b, 204.158 H. W. Quinn, J. S. McIntyre, and D. J. Peterson, Cunad. J . Chem., 1965, 43,159 C. Wu and F. J. Welch, J . Org. Chem., 1965, 30, 1229.160 R. Huttel and H. Dietl, Angew. Chem., 1965, 77, 456.161 J. F. Harrod and A. J. Chalk, Nature, 1965, 205, 208.162 It. S. Coffey, Tetrahedron Letters, 1965, 3809.163 G. C. Bond and M. Hellier, Chem. and Ind.. 1965, 35.ls4R. Cramer, J . Amer. Chern. SOC., 1965, 87, 4717.165 F. H. Jardine, J. A. Osborn, G. Wilkinson, and J. F. Young, Chem. and Ind.,D. P. Tate, A. A. BUSS, J. M. Augl, B. L. Ross, J. G. Grasselli, W. M. Ritchey,2596.1965, 560202 INORGANIC CHEMISTRYstudy of the behaviour of this complex in solution has established anequilibrium 1166, 167(Ph,P),RliCl s (Ph,P),Rh(solvent)Cl + Ph,P.1 [(Ph$)&hCl], + PhSPThe n.m.r.spectrum of a solution of this complex, through which hydrogengas is bubbled, indicates that the solvated bisphosphine compound formsit hydride intermediate, which interacts with the olefin or acetyIene.167Related ruthenium systems RuCl,(PPh,), or RuC12( PPh,), also act ashomogeneous hydrogenating systems.168 The solutions are considered toinvolve solvated intermediates of the type RuC1,(Ph3P),(solvent), x = 2 or 3,but in contrast to the rhodium systems the presence of ethanol as a cosolventis necessary. Catalytic hydrogenation of olefins also occurs with thehalogenocarbonylbistriphenylphosphine complex of rhodium and iridium,[(Ph,P),MCOX]; this process is also considered to occur via a hydride-olefin co-ordinating system.leg The rhodium carbonyl chloride complex,RhCOCl(Ph,P), is also an effective hydroformylation catalyst as is theruthenium complex Ru(CO),(PP~,),.~~~, l70The interaction of butadiene with cyclopentadienyl-manganese tricarbonyl in ultraviolet light gave in addition to theproduct C5H51VfnCO(c4H6) reported previously, two new complexes,C,H5&h(C0) ,butadiene and C,H5( CO) ,Mnbutadiene Nn( CO) 2( C5H5) .I71Dibutadienerhodium( I) chloride has been prepared by reaction of rhodiumtrichloride and butadiene at -5".The X-ray structure of the compoundis reported.172 The synthesis of unsaturated esters from conjugated or non-conjugated dienes, carbon monoxide, and phosphinepalladium halides hasbeen reported for a variety of olefins.173 Dimerisation of norbornadieneby nitrosyliron carbonyl has been studied.174The interaction of iron carbonyl with 1,6-diphenylhexatriene yields atricarbonyl complex.176 The interaction of tetraphenylallene with ironcarbonyl gives a red diamagnetic adduct (Ph,C,)Fe(CO), from which thetetraphenylallene can be displaced with triphenylphosphine.Tetraphenyl-butatriene gives the complex Ph,C,Fe,(CO),. Cumulene is unstable, butmay be stabilised by co-ordination to a metal. The reaction of 1,4-dibromo-but-2-yne with iron carbonyl in the presence of zinc dust yields C4H4Fe,(CO),,as a stable red crystalline compound.176 Tetraphenylallene and tetraphenyl-PoZyene systems.hl.A. Bennett and P. A. Longstaff, Chem. and Ind., 1965, 846.16' J. F. Young, J. A. Osborn, F. H. Jardine, and G. Wilkinson, Chem. Comm.,168 D. Evans, J. A. Oaborn, F. H. Jardine, and G. Wilkinson, Nature, 1965, 208,L. Vaska and R. E. Rhodea, J . Amer. Chem. Soc., 1965, 87, 4970.170 J. A. Osborn, G. Wilkinson, and J. F. Young, Chm. Comm., 1965, 17.171 M. L. Ziegler and R. K. Sheline, Inorg. Chem., 1965, 4, 1230.172 L. Porri, A. Lionetti, G. Allegra, and A. Immirzi, Chem. Comm., 1965, 336.173 S. Brewis and P. R. Hughes, Chem. Comm., 1966, 157, 489.174 P. W. JolIy, F. G. A. Stone, and K. Mackenzie, J . Chem. Soc., 1965, 6416.175 H. W. Whitlock, jun., and Yow Nan Chuah, Inorg. Chem., 1965, 4, 424.176 A. Nakamura, P. J. Kim, and N.Hagihara, J . Organometallic Chm., 1965, 3, 7 .1965, 131.1203KOHL AND LEWIS : TRANSZTION-METAL CARBONYLS 203butatriene also react with chromium carbonyl; addition occurs to the phenylgroup in both cases.177The X-ray structure of dipenteneplatinum(n) chloride has been investi-gated. The axis of one of the double bonds is perpendicular to the PtC1,unit whilst the other double bond is a t 62" to this ~lane.1~8 The proton-proton coupling in the n.m.r. spectra of dieneiron tricarbonyl complexeshas been interpreted in favour of 1,4-addition of iron to the d.ie11e.1~~Sodium borohydride reduction of the complex [C5H5lvC&6(CO)]PE", givesreduction of the co-ordinated benzene to the 1,3-diene, C5H5WC6H,(CO)H.Reduction of the corresponding molybdenum complex with lithium alu-minium hydride gives C,H 5MoC6H6.1s0 The preparation of the cyclohexa-1,3-&ene complex of iridium and the octafluorocyclohexa- 1,3-diene complexof rhodium have been reported.lg0y 181The X-ray structure of c y clo p entadienyl ( benz o ylc y clopent adiene ) cob altestablishes that the benzoyl is exo to the metal atom.In contrast to thephenyl complex the carbon-carbon distances within the cyclopentadienering suggest that the four bonding carbon atoms are in a sp2-hybrid state andbonded symmetrically t o the metal.ls2 However, the structure of dimethyl-mcyclopentadienyl(methylcyc1opentadiene)rhenium shows bond lengths of1-31 and 1.45 A for the part of the cyclopentadiene bonded to the rheniumand favours a n-olefin-o-bonding pattern of the butadiene fragment.ls3 Thefirst perfluorocyclopentadiene complexes have been prepared from cobaltoctacarbonyl, iron carbonyl, and cyclopentadienylcobalt djcarbonyl.In thecobalt compounds [C5F,Co(CO),],, [C5F,Co(CO)C5H5], the ligand bonds asa dienyl, in the iron compound, C,F,[Fe(CO),],, it is suggested that eachdouble bond co-ordinates to separate iron atoms.ls*The isomerisation of cyclo-octa-l,5-diene t o the 1,3-isomer by iridiumand rhodium complexes has been studied; reaction of the 1,5-diene withchloroiridic acid gives the hydride [IrHCl,( 1 ,5-CsH1,)].185 With chromiumcarbonyl, in the appropriate solvents, cyclo-octa-I ,5-diene is transformedinto o-xylene. The cyclo-octa- 1,3-diene reacts with molybdenum andtungsten carbonyl to give complexes of the 1,5-isomer.l86 The stereo-chemistry of the molecules obtained by nucleophilic attack of methoxideion on metal complexes of bicyclopentadienyl has been investigated byn.m.r.spectro~copy.~~~ Nucleophilic attack on the cyclo-octa- 1,5-diene-palladium dichloride complex by ethyl malonate or ethylacetoaceOone leadsto substitution in the organic ring.lS8 The X-ray structure of cyclo-octa-177 A. Nakamura, P. J. Kim, and N. Hagihara, J. Organometallic Chem., 1965,3, 355.178 N. C. Baeziger, R. C. Medrud, and J. E. Doyle, Acta Cryst., 1965, 18, 237.179 R. S. Gutowsky and J. Jon&#, Inorg. Chem., 1965, 4, 430.180 E. 0. Fischer and F. J. Kohl, Chem. Ber., 1965, 98, 2134.Is1R. L. Hunt and G. Wilkinson, Inorg. Chem., 1965, 4, 1270; G.Winkhaus andH. Singer, 2. Naturforsch., 1965, 20b, 602.lE2 M. R. Churchill, J . Organometallic Chem., 1965, 4, 258.18s N. W. Alcock, Chern. Comm., 1965, 177.lS6 J. K. Nicholson and B. L. Shaw, Tetrahedron Letters, 1965, 3533.ls8 G. J. Leigh and E. 0. Fischer, J . Organometallic Chem., 1965, 4, 461.lE7 J. K. Stille, R. A. Morgan, D. D. Whitehurst, and J. R. Doyle, J . Amer. Chem.J. Tsuji and H. Takahaski, J . Amer. Chem. SOC., 1965, 87, 3275.R. E. Banks, T. Harrison, R. N. Haszeldhe, A. B. P. Lever, T. F. Smith, andJ. B. Walton, Chem. Comm., 1965, 30.Sm., 1965, 87, 3282204 INORGANIC CHEMISTRYI ,5-dieneduroquinonenickel indicates that both sets of double bonds fromthe ligands are perpendicular to each other and that the co-ordinated nickelatom has an idealised tetrahedral configuration.lSg The relative bond lengthsof the co-ordinated double bonds for the two ligands are discussed in termsof the stability of the nickel-ligand bonds.A refinement of the crystalstructure of norbornadienepalladium(n) chloride indicates that, contrary tothe initial report, the bond length of the co-ordinated C=C system is barelysignificantly longer than normal.lgO The use of tricarbonyltris( acetonitrile)-tungsten as an intermediate for the preparation of (olefin)W(CO) , complexes,(olefin = cycloheptatriene, cyclo-octatriene, cyclo-octatetraene) has beendeveloped .l 91Aceblene Complexes.-The X-ray structure of the red-orange and darkred isomers, Fe,(CO),(C,H,),, produced from acetylene and iron carbonylshow condensation of three acetylene groups to a 3-methylenepenta-l,4-dienylene bridge in the red-orange isomer and methylcyclopentadienylbridge in the dark red homer.The structure of the violet and black formsof diphenylacetylene-iron carbonyl adducts (Ph,C,)Pe,(CO),, show co-ordination of two diphenylacetylene groups to opposite sides of a triangleof iron atoms, whilst in the black isomer a ferrocyclopentadiene ring isformed with n-bonding from the ring to both iron atoms on opposite sidesof the ring.192 The X-ray analysis of the complex (Ph,C,),Fe(CO), showsit to be a tetraphenylcyclobutadiene derivative.lg3 Diphenylacetylene orhex-3-yne reacts with the hiscarbonylchlororliodium(1) dimer to give cyclo-pentadienonerhodium derivatives.lg4 Hexafluorobut-2-yne reacts withtricarbonyltris( acetonitri1e)tungsten to give an analogous derivative to thecomplexes reported last year, [(CF,) 2C2]3W(NCMe),191 whilst carbonylchloro-bis( tripheny1phosphine)iridium gives the compound (Ph,P) ,COClIr( CF,) ,C2,which in the solid state evolves hexafluorobut-2-yne.This is considered asa derivative of RIP1 with the acetylene bonded by two o-bonds to the metal,and not by a n-acetylene b0nd.1~5 The n-bond structure occurs in therhodium complex (PPh,),RhCl[(CF,),C,] with the acetylene trans to thechloride.146 Hexafluorobut-2-yne also reacts with dicyclopentadienylvana-dium to give a derivative of vanadium(Iv), (C,H,),V(CF,),C,, which isformulated with two a-bonds from the acetylene unit.lg5Ally1 Complexes.-The chemistry and structure of metal-ally1 complexeshas been re~iewed.1~~ Reaction of the lialogenopentacarbonyl anions ofmolybdenum and tungsten [M(CO),X]- (X = C1, Br, I) with ally1 halidesC,H 5kT( Y = C1, Br) give halogen-bridged binuclear allylcarbonyl complexesEt,N[M,Y,(C,H5)2(C0)4] (M = Mo, W).197 Reaction of allene with iron189 M.D. Glick and L. F. Dahl, J . Organometallic Chena., 1965, 3, 200.180 N. C. Baenziger, G. F. Richards, and J. R. Doyle, Acta Cryst., 1965, 18, 925.191 R. B. King and A. Fronzrtglia, Chem. Conam., 1965, 547.192 J. Meunier-Piret, G. S. D. King, and M. Van Meerssche, Acta Cryst., 1965, 19,78; E. H. Braye and W. Hiibel, J . Organometallic Chem., 1965, 3, 38; J. Meunier-Piret,P.Piret and M. Van Meerssche, Acta Cryst., 1965, 19, 85.193 R. P. Dodge and V. Schomaker, J . Organometallic Chem., 1965, 3, 274; ActaCryst., 1965, 18, 614.194 P. M. Maitlis and S. McVey, J . Organometallic Chem., 1965, 4, 254.195 R. Tsumura and N. Hagihara. Bull. Chm. SOC. Japan, 1965, 38, 861.196 M. L. H. Green and P. L. I. Nagy, Adv. Organometallic Chem., 1964, 2, 325.1 9 7 H. D. Murdoch, J . Organometallic Chem., 1965, 4, 119KOHL AND LEWIS : TRANSITION-METAL CARBONYLS 205carbonyl gives the complex [C,H,Fe(CO),], which is considered to have a2,Z’-bis-n-allylene structure. The n.m.r. spectrum suggests the presence ofvalency tautomerism between a n-ally1 and a n-olefin-bonded structure.1a*The X-ray structure of tricarbonylbicyclo[3,2,l]octadienyliron tetrafluoro-borate favours interaction by separate n-ally1 and n-olefin bonds, ratherthan a delocaljsed n-system.lg9 Reactions of ruthenium trichloride withisoprene yields a bridged chloro-complex of ruthenium with 2,7-dimethylocta-2,6-diene, the ligand co-ordinates to the metal with double n-ally1 chelakingarrangement [see (S)] .200iI cAcyl- and allyl-cobalt tetracarbonyl react with ap-unsaturated aldehydcsor ketones to form 1-acyloxy-n-allylcobalt tricarbonyl.The complexes aremost readily isolated as the monotriphenylphosphine derivative.201 Thereactions of (C, ,H,,)RhCb, produced from all-trans- cyclododeca- 1,5,9- trieneand rhodium trichloride, with carbon monoxide, ethylene, and a variety ofnitrogen ligands have been reported.The X-ray structure of the ethylene-diamine complex, trans-dichloro( ethy1enediamine)cyclododeca- I ,5-dienyl-rhodium(u1) indicates a bonding through a n-allylic system and the presenceof an unco-ordinated olefin gr0up.20~ The structure of acetylacetonato-(cyclo-octa-2,4-dienyl)palladium(11), also involves a co-ordination of an a,llylgroup with an unco-ordimted double bond remaining in the cyclic ligandgrouping .203A repeat of the X-ray structure with three-dimensional data,204 and a tlQ8 A. Nakamura and N. Hagihara, J . Organmnetallic Chern., 1965, 3, 480.lQ9 T. N. Margulis, L. Schiff, and M. Rosenblum, J . Ainer. Chm. SOC., 1965, 87,L. Porri, M. C. Gallazzi, A. Colombo, and G. Allegra, Tetrahedron Letters, 1965,3369.4187.201 R.F. Heck, J . Amer. Chem. SOC., 1965, 87, 4727.202 G. Paiaro, A. Musco, and G. Diana, J . Organometallic Chent., 1965, 4, 466.203 M. R. Churchill, Chem. Comm., 1965, 635.2 0 4 W. E. Oberhansli and L. F. Dahl, J . Organometallic Chem., 1965, 3, 43206 1NORUANI.O OHEXISTRY-140°c,205 of the z-allylpalladium chloride dimer indicates that the planeof the three allylic carbons is not perpendicular to the plane of the palladiumchloride bridged system; the dihedral angle between the two planes beingreported as 108" and 111.5". Interaction of z-allylpalladium chloridedimers with triphenylphosphine converts the compounds to o-ally1 complexes.A study of the n.m.r. spectra of the complex chlorotriphenylphosphine-(methylallyl)palladium(n), suggests a bonding structure of the ally1 groupintermediate between a n-ally1 and o-ally1 arrangement.206 A series ofn-allylpalladium complexes with bridging carboxylates have been preparedfrom the corresponding chloride with the silver carboxylate 207 and complexescontaining z-allylic palladium cations by interaction of the n-allyl-chloro-dimer with ethylenediamine or bipyridyl.20* Di-z-cyclododecenepalladiumchloride is formed from cyclododecene and palladium chloride.20 Dimerisa-tion of propene with palladium chloride in glacial acetic acid leads to acomplex formulated as a bridged chloro-mallyl complex.210 Nucleophilicattack occurs on the mallyl system of the z-allylpalladium chloride dimerby l-morpholinocyclohex-1 -ene, ethyl acetoacetate, and diethyl malonate.21fCarbonylation of allenepalladium complexes, and other allylic derivativesto give unsaturated esters has been studied.211 The reaction of octafluoro-cyclohexa-lY3-diene with di-z-cyclopentadienylnickel gives a complex (9) inwhich a n-cyclopentadienyl ring is condensed with the fluorocarbon to yielda bicyclic system with a z-ally1 bond to the metal.ls1F F FThe formation ofCyclobut adienediallylzinc has been studied.212Complexes.-cis-3,4-Dichlorocyclobutene reacts with ex-cess of iron ennacarbonyl to give cyclobutadieneiron tricarbonyl ; withtrans-dibromobenzocyclobufene, iron ennacarbonyl gives a cyclobutadienecomplex (The reactions of cyclobutadieneiron tricarbonyl indicate that it is aromatic,206 A.E. Smith, Acta Cryst., 1965, 18, 331.206 J.Powell, S. D. Robinson, and €3. L. Shaw, Chem. Comm., 1965, 78.207 S. D. Robinson and B. L. Shaw, J . Organometallic Chern., 1965, 3, 367.208 G. Paiaro and A. Musco, Tetrahedron Letters, 1965, 1583.209 R. Huttel and H. Dietl, Chern. Ber., 1965, 98, 1753.210 I. I. Moiseer, A. P. Belov, and G. Yu. Pek, Rzcss. J . Inorg. Chern., 1966, 10,180.J. Tsuji, H. Takahashi, and M. Morikawa, Tetrahedrort Letters, 1965, 4387;J. Tsuji and T. Susuki, {bid., p. 3027; J. Tsuji and S . Hosaka, J . Arner. Chew. SOC.,1965, 87, 4975.21sK. H. Thiele, W. Hanke, and P. Zdunneck, 2. anorg. Chem., 1965, 337, 63;J . Organometallic Chem., 1965, 4, 10.218 G. F. Emerson, L. Watts, and R. Pettit, J. Amer. Chem. Soc., 1965, 87, 131KOHL AND LEWIS : TRANSITION-METAL CARBONYLS 207and find a close parallel in the substitution reactions of f e r r ~ c e n e .~ ~ ~ Decom-position of cyclobutadieneiron tricarbonyl in the presence of acetylenederivatives gives compounds with the Dewar benzene structure : phenylace-tylene gives hemi-Dewar biphenyl (1 l).215 Attempts to prepare compoundsof this type from tetraphenylcyclobutadienepalladium dichloride wereunsuccessfuL21eThe reaction of tetraphenylcyclobutadienepalladium or nickel dihalide hasbeen studied with cyclopentadienyliron dicarbonyl dimer and cyclopenta-dienylmolybdenum tricarbonyl dimer. With the iron compound, transferof cyclopentadienyl to the palladium or nickel occurs [ (Ph,C,)MC,H,]FeX,(M = Pd, Ni; X = C1, Br), but with the molybdenum compound thereaction gives (Ph,C4)Mo(C5H,)CO*X (X = Br, Cl).217 The cyclobutadiene-cyclopentadienylpalladium bromide reacts with cobalt octacarbonyl to give[Ph,C,]Co(C,H,). This is the first example of the simultaneous transferof two organic n-ligands from one metal to another.218 Reaction of tetra-phenylcyclobutadienepalladium dibromide with cobalt carbonyl yields then-comp1ex[Ph4C4]Co(C0),Br. This complex is paramagnetic, per N 3.5 B.M.The compound reacts with benzene or methyl-substituted benzenes, in the pre-sence of aluminium chloride to give the complexes, (~-arene)(Ph,C,)CoBr.~~~Diphen yla ce t ylene and di-p - c hlor op hen y la ce t y lene react with bis benz onitrile -palladium &chloride to give a polymeric cyclobutadienepalladium dichloridepolymer in which two cyclobutadienepctlladium dichloride units are con-nected by palladium dichloride units, [ (Ph,C,)PdCl,](PdCl,>,[ PdCl,( Ph,C,)].Alkoxides react with tetraphenylcyclobutadiene-metal derivatives to givecyclobutenyl derivatives by nucleophilic attack on a carbon atom of thecyclobutadiene ring.Both exo- and endo-derivatives may be obtained.220The X-ray structure of the two isomers of the cyclobutenyl complexes(Ph,C,OC,H,PdCl) have been determined.221 The cyclobutenylnjckelcomplex (Me4C4C5H,)NiC ,H5 is obtained by reaction of tetramethyl-butadieneniclcel dichloride with cy clopentadienylsodium ; the X-raystructure indicates a non-planar 1,2,3,4-tetramethyl-exo-cyclopentadienyl-butenyl anion bonded to the nickel by an allylic fragment of the cyclo-butenyl ring.Z22Cyclopentadiene Complexes.-The synthetic methods used in the pre-paration of cyclopentadiene-metal complexes has been reviewed.223 The13C n.m.r.spectra of a series of transition-metal cyclopentadienyl andcyclopentadienyl-carbonyl derivatives 224 and the mass spectra of someSoc., 1965, 87, 3254.G. D. Burt and R. Pettit, Chem. Comnz., 1965, 617.214 J. D. Fitzpatrick, L. Watts, G. F. Emerson, and R. Pettit, J . Amer. Chem.215 L. Watts, J. D. Fitzpatrick, and R. Pettit, J . Amer. Chem. SOC., 1965, $7, 3253;218 R. C. Cookson and D. W. Jones, J . Chem. SOC., 1965, 1881.a17 P. M. 3laitlis and A. Efraty, J . Organometallic Chem., 1965, 4, 172.21* P. M. Maitlis, A. Efraty, and M. L. Games, J. Amer. Chm. Soc., 1965, 87, 719.P. M. Maitlis and A. Efraty, J . Organometallic Chem., 1965, 4, 175.220P. M. Maitlis, D. Pollock, M. L. Games, and W. J. Pryde, Canad. J . Chem.,221 L. F. Dahl and W. E. Oberhansli, Inorg. Chem., 1965, 4, 629.222 W. Oberhansli and L. F. Dahl, Inmg. Chem., 1965, 4, 150.223 J. Birmingham, Adv. Organometallic Chem., 1964, 2, 365.224P. C. Lauterbar and R. B. King, J . Amer. Chem. Soc., 1965, W, 3266.1965, 43, 470208 INORGANIC CHEMISTRY7t- bonded organometallic compounds have been reported.225 The X-raystructure of the carbon-bridged cyclopentadienyliron complexes, a-oxo-1 ,l'-trimethyleneferrocene 226 and 1 ,l'-tetramethylethyleneferrocene, havebeen determined.227 In the cc-keto-complex the cyclopentadienyl rings areparallel to each other and nearly eclipsed, whilst in the ethylene-bridgedcompound the rings are tilted with respect to each other with an angleof 23" between the planes. The details of the structure of the moleculebiscyclopentadienylmolybdenum dihydride discussed last year have beengiven.228 In tricyclopentadienyluranium chloride, the three cyclopenta-dienyl rings and chlorine atom are arranged tetrahedrally around theuranium .229 The synthesis of the first transuranic cyclopentadienyl com-plex has been made, (C,H,),PU.~~* The radiochemical synthesis of aneptunium compound is also reported :231B-239U(C5H5)3C1 + 239Np(C,H,),C1.23 min.The first cyclopentadienyl complexes of bivalent lanthanides have beenprepared in dicyclopentadienyl-europium and -yttrium ;232 the compoundsare ionic, being similar to the calcium compound. The first cyclopentadienylisonitrile complexes of the lanthanides are also reported for iM(C5H,),CNC,H,(M = Y, Ho, Tb).233The reactions of dicyclopentadienyltitanium dichloride with hydrogens~lphide,~,~ ammonia, rneth~lamine,~35 and the anion (MNT)2- 236 havebeen reported. Methylcyclopentadiene( cyclopentadieny1)dimethylrhenium isformed from methyl iodide and 1,l -dilithiumdicyclopentadienylrheniumhydride which in turn is formed from dicyclopentadienylrhenium hydrideand n-b~tyl-lithium.~~' The binuclear ions [ C ,H 5Fe( CO) 2-X-Fe(CO) 2C5H5]+(X = Br, I), have been prepared by reaction of dicarbonylcyclopentadienyl-iron bromide or iodide with aluminium chloride. The ions are sensitive tonucleophilic attack to give [C,H,Fe(CO),X]+ (X = py, NCPh, NH,Ph).238The methoxycarbonyl complexes of iron, MeOCOFe( CO) 2( C5H,), andmanganese, MeOCOIL\/In(NO)(CO)C,H,, have been obtained.239 The firstn-bonded organic complex of platinum(1v) has been obtained as trimethyl-c yclopent ad ienylplatinum( IV) . 24 O2 2 5 N. Maoz, A. Mandelbaum, and M. Cais, Tetrahedron Letters, 1965, 2087.226 N. D. Jones, R. E. Marsh, and J. H. Richards, Actu Cryst., 1965, 19, 330.z2' M. B. Laing and K. N. Trueblood, Actu Cryst., 1965, 19, 373.228 M. Gerloch and R. Mason, J. Chem. Soc., 1965, 296.2zB C. M70ng, T. M. Yen, and T. Y. Lee, Acta Cryst., 1965, 18, 340.23O F. Baumgartner, E. 0. Fischer, B. Kanellakopulos, and P. Laubereau, Angew.2 3 1 F. Baurngartner, E. 0. Fischer, and P. Laubereau, Naturwiss., 1965, 52, 560.232 E. 0. Fischor and H. Fischer, J . Organometallic Chern., 1965, 3, 181.233K. 0. Fischer and H. Fischer, Angew. Chem., 1965, 77, 261.2 3 4 H . Kopf and IX. Schmidt, Angew. Chem., 1965, 77, 965.235A. Anagnostopoulos and D. Nicholls, J . lnorg. Nuclear Chem., 1965, 27, 339.336 H. Kopf and M. Schmidt, J. Organometallic Chem., 1965, 4, 426.237 R. L. Cooper, M. L. H. Greon, and J. T. Moelwyn-Hughes, J . Organometallic238 E. 0. Fischer and E. Moser, J . Organometallic Chem., 1965, 3, 16; 2. Naturforsch.,239 R. B. King, M. Bisnette, and A. Fronzaglia, J. Orguizonaetallk Chern., 1965, 4,2 4 0 % D. Robinson and B. L. Shaw, J . Chem. SOC., 1965, 1529.Chena., 1965, '77, 866.Chern., 1965, 3, 261.1965, 20b, 184.256KOHL AND LEWIS : TRANSITION-METAL CARBONYLS 209An interesting development in the chemistry of n-complexes has beenthe preparation of a series of carborane analogues of cyclopentadienylcompounds ; reduction of the ion BgC2H, 2- with sodium in tetrahydrofuranand interaction of the resultant ion (BgC2Hll)2- with ferrous chloride givesthe ion [Fe(BgC2H,l)2]2-, this oxidises readily to the ion [Fe(BgC,Hl,),]-.241The (B,C2H,,)2- ion is considered to contribute six electrons to the bondingand to be bonded to the metal through open faces of the BgC2Hl12-icosahedraand be analogous to the behaviour of n-cyclopentadienyl groups.The cyclopentadienyl derivative [ (C5H5)(BsC,H,l)Fe] and the ion[(C,H5)(BgC2H11)Fe]- have also been prepared by carrying out the reactionin the presence of cyclopentadienylsodium.242 A determination of the X-raystructure of the compound [C,H,Fe(B,C,H,,)] confirms the bonding srrange-inent suggested for the carborane group.243 The tricarbonyl derivatives ofmanganese and rhenium, Cs[(B,C2H,,)M(CQ)3] (M = Mn, Re) are preparedfrom the sodium salt and the corresponding pentacarbonyl-metal bromide.244The cobalt complexes [(BsC2Kll)2Co]n- (n = 1, 2) and [Co(C5H5)(B9C2Hll)]have also been reported.245 A study of the e.s.r. spectra of a series of theiron(m) salts suggest similar bonding of the carborane to the cyclopenta,dienylsystem .24Metal-Arene Complexes.-The far-infrared spectra of arenetricarbonyl-chromium derivatives have been discussed in terms of molecular orbitalthe0ry.~~7 The molecular structure of benzene and hexamethylbenzenetricarbonyl have been determined and the data favour a complete delocalisa-tion of the n-electron system within the co-ordinated benzene, with D,,symmetry.248 The electron diffraction of gaseous dibenzenechromiuin isinterpreted in a similar inanner.249Vanadium carbonyl reacts with aromatic compounds to give the newcationic species [ V( CQ),L]+[V(CO),]- (L = 1 ,%dimethyl-, 1,2,3-trimethyl-,1,2,4,5-tetramethyl-, and hexamethyl-benzene). Poor yields of the relatedcompounds were also obtained with anisole and naphthalene .2so Dimesit -ylenevanadium rexts with carbon monoxide to give [V(CGH,Me3),][V(CO),].As the [v(co)6]- ion may readily be oxidised to vanadium carbonyl thisprovides a good route to vanadium carbonyL251 Tricarbonylanthrscene-chromium has been prepared and n.m.r. studies indicate that the Cr(CO),group is bonded to the outer ring of the a n t h r a ~ e n e . ~ ~ ~ Dibenzene-chromiumand -molybdenum react with terpyridyl (terpy), in cyclohexane to giveM(terpy) 2, Benzenechromium tricarbonyl with phenanthroline(phen) or2p1 M. F. Hawthorne, D. C. Young, and P. A. Weper, J. Amer. Chem. Soc., 1965,87. 1818. - _'Z82M. F. Hawthorne and R. L. Pilling, J. Amer. Chem. SOC., 1965, 87, 3987.243 A. Zalkin, D. H. Templeton, and T. E. Hopkins, J . Amer. Chenz. SOC., 1965,244M. F. Hawthorne and T. D. Andrews, J. Amer. Chem. Soc., 1965, 87, 2496.246 X. F. Hawt,horne and T. D. Andrews, Chenz. Comm., 1965, 443.246 A. H. Malri and T. E. Berry, J. Amer. Chem. Soc., 1965, 87, 4437.2 4 7 D. A. Brown and D. G. Carroll, J. Chenz. Soc., 1965, 2522.2p* 35. F. Bailey and L. F. Dahl, Inorg. Chenz., 1065. 4, 1395, 1314.249 A. Haaland, Acta Chem. Xcand., 1966, 19, 41.250 F. Calderazzo, Inorg. Chem., 1965, 4, 223.251F. Calderazzo and R. Cini, J. Chenz. SOC., 1965, 518.252 B. R. Willeford and E. 0. Fischer, J. Organo?netallic Chem., 1965, 4, 109.87, 3988210 INORGANIC CHEMISTRYbipyridyl(bipy) give Cr(phen),, Cr(bipy),, and with ferpyridyl Cr(terpy).253The first series of substitution reactions of dibenzenechromium have beenreported, utilising the reaction of pentyhodium with dibenzenechromiumas the intermediate r e a c t i o ~ ~ ~ 4 Reaction of methoxycyclohexadienes withchromium, molybdenum, or tungsten carbonyl gives the arenemetal tricar-bony1.255 A new bisarenemetal complex has been prepared with two metalatoms contained between two arene rings, by reaction of palladium dichloridewith a,lminium, aluminium chloride, and benzene, the structure of thecompound [PdAl&l,(C6H6)], is shorn in ( 12).256I I I II ICI-Al- CI-AI -Cl -P d-CCI - A l - CI -41 - CICI CI CI CI (12)IThe stereochemistry of tricarbonylcycloheptatrienechromium derivativesobtained by anionic addition to the tricarbonylcycloheptatrienechromiumsalts has been established as the exo-isomers. The endo-isomers are preparedby reaction of substituted cycloheptatriene with chromium hexacarbonylor tripyridinechromium tri~arbonyl.~~' The evidence for the stabilisationof aromatic carbonium ions by n-complexing with a metal carbonyl hasbeen discussed.258 The preparation of a cyclo-octatetraenemolybdenumtricarbonyl complex has been reported and the protonated compound,[C,H,Mo(CO), I+, has been formulated as a monohomotropylium derivative.259153 H. Behrens, K. Meyer, and A. Miiller, 2. ~aturforsck., 1965, ZOb, 74.254 E. 0. Fiecher and H. Bmnner, C h . Ber., 1965, 98, 175.s66A. J. Birch, P. E. Cross, and H. Fitton, Chem. Cmm., 1965, 366.266 G. Allegra, A. Immirzi, and L. Porri, J . Amer. Chem. SOC., 1965, 87, 1394.257 P. E. Baikie, 0. S. Mills, P. L. Pauson, Cr. H. Smith, and J. Valentine, Chem.268 J. D. Holmes, D. A. K. Jones, and R. Pettit, J. Organometallic Chem., 1965,S. Winstein, H. D, Kaesz, C. G. Kreiter, and E. C. Friedrich, J . Amer. Chem.Comnt., 1965, 425.4, 324.Soc., 1965, 87, 3267

ISSN:0365-6217    

DOI:10.1039/AR9656200131

出版商:RSC    

年代:1965

数据来源: RSC

摘要:

1. INTRODUCTIONBy W. D. Ollis(Department of Chemistry, University of S h W )and J. H . Ridd(Department of Chemhtry, Univem&y College, London, W.C.1)SEVERAL changes in the coverage of this Report have been made this yearin the hope of meeting the demands of current trends in organic chemistry.Two new sections have been introduced and several of the traditional sectionshave been modified. The new section on Organometallic Compounds isdesigned to cover primarily the chemistry of organic derivatives of the Don-transition metals, with particular reference to those compounds containingmetal-carbon bonds, The behaviour of these non-transition-metal deriva-tives 8s organic compounds is emphasised and this section is intended to becomplementary to the discussion of the organic chemistry of transition-metalcomplexes which is retained in the Inorganic Chemistry Report.A further change is the introduction of a new section in Biosynthesis.This is clearly an important and rapidly developing area of natural productchemistry which is of considerable general interest.In the past separate sections have usually been allocated to steroids,terpenoids, and carbohydrates, but this year steroids and terpenoids havebeen included in the section on Alicyclic Compounds.The chemistry ofmonosaccharides of general interest is discussed in the Eeterocyclic sectionand polysaccharides are reviewed in the Biological Chemistry Report.Previously amino-acids, peptides, and nucleic acids have been reviewed attwo- or even three-yearly intervals, but clearly the breadth, importance, andgeneral interest of these areas of research demand frequent summary andappraisal.In this Report these sections deal only with results obtainedduring 1965. The inclusion of a section on Nucleic Acids in the OrganicChemistry Report is debatable. However, as nucleic acids were not to bediscussed specifically in the Biological Chemistry Report, an attempt hasbeen made t o review progress in this field in a language which is intelligibleto the non-specialist, an objective which is surely one of the major functionsof Annual Reports.It is customary in the Introduction to summarise important advancesthat have been made during the preceding year, but it would be invidiousto attempt to provide a detailed commentary this year.The most obviousimpression gained by reading the following Reports is that organic chemistryis in an extremely virile state: important advances have been made on allfronts extending from the physical to the biochemical borders of the subject,Probably the most significant developments in theoretical organicchemistry involve the use of simple and satisfying arguments based onthe symmetry of molecular orbitals to predict the steric consequences o212 ORGANIC CHEMISTRYelectrocyclic processes. The relative facility of thermal and photochemicalintermolecular cyclo-additions can now be understood and these views havebeen extended to include some rearrangement reactions. The ideas ofWoodford and Hoffman promise to provide a refreshingly new approach anda new nomenclature to a large area of chemistry.Many interesting structural details are emerging from nuclear magneticresonance studies of carbonium ions at low temperatures.The nature ofthe intermediate carbonium ions involved in certain solvolyses continuesto be examined mainly on the basis of kinetic studies and product analyses.Relative reaction rates in electrophilic aromatic substitution are also pre-senting a number of problems. There is increasing evidence that loosen;-complexes can be intermediates, but the extent to which the formation ofsuch complexes influences the overall rate of substitut'ion is not clear.Progress in synthetic organic chemistry is clearly demonstrated, not onlyby the continuing discovery of new reagents and methods, but also by thesuccessful synthesis of a remarkable range of organic compounds during thepast year.These achievements include many novel compounds such ascyclobutadiene (it really can be made) and derivatives of tetrahedrane, thecalicenes, Dewar benzene, prismane, benzvalene, brendane, brexane, theasteranes, and congressane, now to be called diamantane. Clearly exoticcompounds are entitled to exotic names. The claim (1965) to have syn-thesised a derivative of tetrahedrane has since been retracted (1966).The use of physical methods, including mass spectrometry and X-raycrystallography, continues to be widely applied, particularly in the examina-tion of natural products. This year the first isolation of a naturally occurringcumulene has been recorded and fucoxanthin is shown to be an alleniccarotenoid. A gap in the terpenoid class is filled by the discovery of thesesterterpenes, ophiobolin and gascardic acid, and the recognition of naturalrepresentatives, androcymbine and melanthioidine, of the 1 -phenylethyliso-quinoline class of alkaloids is important in relation to the biosynthesis ofcolchicine. The determination of the complete sequence of seventy-sevennucleotide units in alanine transfer-RNA represents progress a t a differentlevel of molecular complexity as does the total synthesis of insulin.Inconnexion with the synthesis of natural macromolecules, solid-phase syn-thesis provides exciting possibilities. Elegance in the total synthesis ofnatural products is exemplified by a number of successful syntheses of ter-penoids and alkaloids including colchicine, and Iboga, Hunteria, and Aspi-dosperm type alkaloids.The study of the details of the biosynthesis ofalkaloids by Barton and Battersby and the elucidation of the subtle stereo-chemical details of steroid biosynthesis by Cornforth and Popjak indicatethe extent to which detailed description of biosynthetic pathways is nowpossible.The volume of the current literature to be summarised in the OrganicChemistry Report has placed challenging and very time-consuming demandsupon the Reporters. Omissions are inevitable, but we hope that the reasonsfor these will be appreciated2. PHYSICAL METHODS OF STRUCTURE DETERMINATIONBy I).H. Williams (A, B, and 0 )(University Chemical Lahora&y, LensJEeH Road, Cambridge)and A. Horsfield (D)(Varian Research Laboratory, Molesey Road, Walton-on- T h a w )A. OPTICAL ROTATORY DISPERSION AND CIRCULAR DICHROISMTwo important books dealing with applications of optical rotatory dis-persion (0,r.d.) and circular dichroism (c.d.) in organic chemistry have beenpublished in 1965.1,2 Research advances have occurred in the field ofvariable-temperature studies 3, 4 (as low as - 192 "c) and measurementscan now be made fairly routinely down to 200 mp.Vmiable-tempemhe Studies.-Measurements a t very low temperaturesmay be made by use of EPA ether (5 vo1.)-isopentane (5 vo1.)-ethanol(2 vol.)as solvent? A temperature-variable c.d.curve may be afforded by 8 com-pound if it is conf'ormationally heterogeneous or if increased solvation occursat lower temperatures; the two phenomena can be distinguished by the useof various solvents and by the blue shift which accompanies increased sol-vation.5 Similarly, the presence of multiple Cotton effects arising from ann+n* transition of a carbonyl chromophore can be explained in terms of asolvation equilibrium involving differently solvated species and/or a confor-mational eq~ilibrium.~ Multiple Cotton effects cause complications in theinterpretation of a c.d. curve; it can be shown that whenever two Cottoneffects of similar amplitudes but opposite sign are superimposed with theirindividual maxima separated by 1-20 mp, a complex c.d.curve with twoextrema of opposite sign separated by ca. 30 mp will arise.5 The rotationalstrength of (+)-2-t-butylcyclohexanone ( I ) is temperature-dependent and,although a solvational equilibrium cannot be ruled out, the data have beeninterpreted in terms of a conformational equilibrium involving restrictedrotation in the t-butyl group. The l7b-acetyl side-chain of 20-oxo-steroidsexists predominantly in conformation (2) (view along the @-174-20 bond),although an additional contributor is indicated by temperature-dependentcircular dichroism.Chromophoric Derivatives.-If instruments are not available to facilitatemeasurements on amino-acids at low wavelengths, dimedone-amino-acidcondensation products ( 3 ) can be employed. * N-Neopentylidene deriva-tives (4) of a-amino-acid esters show anomalous dispersion curves with thefirst extremum in the 250-mp region; in the compounds studied, the deri-vatives with t'he L-codguration show a negative Cotton effect, and thosewith the D-configuration a positive 10 Other derivatives which mayprove useful include N-methylthionamides (5),11 azomethines in general,12N-chloroamines,l3 and thiolacetates.l4 N-Thiobenzoyl l5 and N-salicyli-dene l6 derivatives of amino-acids have also been investigated.(3) (4)SR - & N H M ~Amins-acids a d 1Peptides.-Low-wavelength measuremenfxs now permitthe absolute configurations of amino-acids to be obtained directly fromo.r.d.17-19 or c.d.curves.2o Amino-acids show a Cotton effect a t about216 mp; L-amino-acids show positive Cotton effects in acidic solution.17, 18In both neutral and acidic conditions, members of the L-series show asteeply descending negative '' tail " between 200 and 225 mp, and mem-bers of the D-series, a steeply ascending positive one.Additional htudieshave appeared on the 0.r.d. and c.d. of ~ e p t i d e s . ~ l - ~ ~ In an importantreview article,23 it has been reported that helical polypeptides show acomplex dichroism in the far-ultraviolet region, with three components(192, 204, 206 mp), characteristic of the helical array of peptide groups;these workers a3 have extended ad. measurements down to 185 mp.Amiraes and Alkaloids.-Saturated amines show steeply ascending ordescending 0.r.d. curves below 225 mp owing to a Cotton effect associatedwith the excitation of the non-bonding electrons on nitrogen;2* In amineisso far examined, possessing a single cc-asymmetric centre, the absolutecontiguration can be assigned from the direction of the dispersion curvebetween 200 and 225 mp, provided either that the amine is not protonated orthat the compound contains 8 chromophore absorbing above 200 mp.Benzyltetrahydroisoquinolines 24, 25 and bisbenzyltetrahydroisoquinolines 25show mult'iple Cotton effects which can be related to the stereochemistry ofthe compounds.Aporphine alkaloids exhibit a Cotton effect of high ampli-tude centred at 235-245 mp, the sign of which is diagnostic of the absoluteconfiguration of the asymmetric carbon atom adjacent to nitrogen.26Dienes and af3-Unsaturated Ketones : Non-planar Chromophores.-Using a very simplified model for the n+n* transition of or/?-unsaturatedketones, a relationship has been derived between the chirality of the non-planar chroniophores ( i e ., the helical sense of the four-carbon system) andthe sign of their c.d. Cisoid cyclohexenones give a positive (nega-tive) c.d. curve if the double bond lies in n positive (negative) octant.28The sign of the Cotton effect of a number of non-planar homoannular cisoiddienes can be predicted in every instance in terms of the chirality of theThe intensity of the absorption bands has been calculated as afunction of the skew angle of the diene system; where the skew angle isknown in one case (from X-ray data), the shape of the experimentallyobserved 0.r.d.curve is in excellent agreement with that calculated.30Mhcebeous.-The c.d. of 4/3-nitro-5a-cholestane and its G/?-analogueare enanti~meric;~~ models indicate that the nitro-groups are " fixed " bythe C-10 methyl groups and two axial hydrogens [see (6) and (7)].The absolute configuration of (+)-methyl n-butyl sulphoxide (8) is (8)and it has a positive Cotton effect;s2 absolute configuration of other methylalkyl sulphoxides can now be assigned by comparison of 0.r.d. curves withthat of (8). The cyclopropane and ethylene oxide rings of cyclopropylketones and epoxy-ketones make contributions to the Cotton effect at ca,290 mp, which are opposite in sign to those made by alkyl groups.33 In thefield of magneto-optical rotation spectra, zinc phthalocyanine and magnesiumphthalocyanine have the largest magnetic rotations observed to date.34a-Substituted acids have been extensively in~estigated.~~B. MASS SPECTROMETRYData, Analysis.-A computer programme has been written for theanalysis of high-resolution mass spectra.36 The computer print-out giveselemental compositions of all ions in the spectrum, which are listed accordingto their heteroatom content; the technique has been used to aid the structureelucidation of a new Pleiocarpa alkal~id.~' A programme has been devisedfor the construction of Tables of empirical formulze ordered according totheir masses.38 Data from the spectra of up to 150 pure compounds can beused to determine automatically both the qualitative a,nd quantitativecomposition of a sample mixture (if the spectra of all components are pre-sent in the spectral library) without requiring any advance information as tot'he sample compo~ition.~~Fragmentation Mechanisms.-It has been pointed out that a t lowenergies of bombarding electrons, some mass-spectral fragmentation pro-cesses show a striking similarity to photochemical decompositions.*0 Studiesof the McLafferty rearrangement [ (9) -+ (lo)] in some oxo-steroids indicatethat a critical intreratomic distance ( < l * S A) between the y-hydrogen atomand carbonyl oxygen atom is required before the rearrangement can- c H c H R'3.1V.E. Shashova, J. Amer. Chefit. Soc., 1965, 87, 4044.35 J. Cymerman Craig and S. I<. Roy, Tetrahedron, 1965, 21, 1847; A.Fredga,J. P. Jennings, W. Klyne, P. M. Scopes, B, Sjoberg, and S. Sjoberg, J. Chem. Soc.,1965, 3928; T. R. Emerson, D. F. Ewing, W. Klyne, D. G. Ncilson, D. A. V. Peters,L. H. Roach, and R. J. Swan, ibid., p. 4007.36 K. Biemann and W. McMurray, Tetrahedron Letters, 1965, 647.37 H. Achenbach and K. Biemann, Tetrahedron Letters, 1965, 3239.38 D. D. Tunnicliff, P. A. Wadsworth, and D. 0. Schissler, Analyt. Chem., 1965,3g D. D. Tunnicliff and P. A. Wadsworth, Analyt. Chem, 1965, 37, 1082.40 N. J. Turro, D. C. Neckers, P. A. Lsermakers, D. Seldner, and P. D'Angelo,*l C. Djerassi, G. von Mutzenbecher, J. Fajkos, D. H. Williams, and H. Budzikiewicz,37, 543.J . Amer. Chem. Soc., 1965, 87, 4097.J. Amer. Chem. Soc., 1965, 87, 817WILLIAMS AND HORSFIELD : STRUCTURE DETERMINATION 21'7A pair of epimeric steroidal tertiary alcohols [see partial structures (1 1)and (12)] eliminate water by distinct mechanisms upon electron impact ; (1 1)eliminates DHO and H,O to approximately equal extents, whereas (12), inwhich the ring hydrogens are more accessible to the OH-group, decomposesalmost exclusively by loss of H,O.42 Quaternary ammonium halides frag-ment in three main ways: (a) by a Hoffmann degradation, ( b ) by formation ofa tertiary amine and an alkyl halide, and (c) by formation of a tertiary aminewith an associated substitution by the halogen atom.43 In the retro-Diels-Alder fragmentation, stabilisation of the positive charge in the molecular ionis important in determining whether an ionised ene or diene fragment will bef0rrned.4~ Thus, (13) gives a spectrum in which the relative abundance ofM - 54 to m/e 54 is much greater than in the spectrum of (la), because theformation of a is more favourable when R = Me (tertiary carbonium ion).Bicyclopentane (59) reacts with dicyanoacetylene to give compound(60) .g3 Tetracyanoethylene oxide (61) undergoes some remarkable cyclo-additions.It reacts with ethylene a t 140" to give tetracyanotetrahydro-furan (62) in >80% yield. Under the same conditions, the benzofuran (63)is formed (35%) with benzene.94 The mechanism involves pre-equilibriumof (61) with an activated species.95 Linn and Benson note that (63) does8(59)NC CNG oNC CNnot react with tetracyanoethylene or maleic anhydride ; 94 probably, anelectron-rich dienophile is needed to achieve a Diels-Alder addition withinverse electron demand.Spontaneous dimerisations of ketens (with theexception of lieten itself) appear to give cyclobutane-l,3-diones as themajor primary products.96More than ten different papers dealing with 1,3-dipolar cycloadditionshave appeared from Huisgen's The reactions of A2-triazolineswith isocyanates, however, do not fall into this mechanistic category.981,Q-Dipolar additions appear to be relatively rare.99Sigmatropic Rearrangements.-In a further illuminating paper, R. B.Woodward and R. Hoffmann have defined an i,j-sigmatropic rearrange-ment as the '' migration of a o-bond, flanked by one or more n-electronsystems, to a new position whose termini are i - 1 andj - 1 atoms removedfrom the original bonded loci, in an uncatalysed intramolecular process."Thus, the Claisen rearrangement and its all-carbon analogue (the Coperearrangement) are 3,3-sigmatropic shifts.I n cases where a free choice oftransition state geometry is possible the Cope rearrangement [(64) -+ (65)]has been known to proceed more readily through the chair-like four-centreDsP. G. Gassman and I(. Mansfield, Chem. Comm., 1965, 391.94 W. J. Linn and R. E. Benson, J . Amer. Chem. Soc., 1965, 87, 3657.O6 D. G. Farnum, J. R. Johnson, R. E. Hess, T. B. Marshall, and B. Webster,J . Amer. Chem. SOC., 1965, 87, 5191.9 7 Part 12, G. Grashey, R. Huisgen, K. K. Sun, and R. M. Moriarty, J . Org.Chenz.,1965, 30, 74; Part 23, R. Huisgen, R. Knorr, L. Mobius, and G. Szeimies, Chem. Ber.,1965, 98, 4014; see also E. Grigat, R. Putter, and E. Miihlbauer, ibid., p. 3777.J. E. Baldwin, G. V. Kaiser, and J. A. Rornersberger, J . Amr. Chem. SOC.,1965, 87, 4114; R. Huisgen, R. Grashey, J. M. Vernon, and R. Kunz, Tetrahedron,1965, 21, 3311.laoR. B. Woodward and R. Hoffmann, J . Amer. Chem. SOC., 1965, 87, 2511.W. J. Linn, J . Amer. Chem. SOC., 1965, 87, 3665.9 9 R . Huisgen and K. Herbig, Annalen, 1965, 688, 98HOFFMANN : REACTION MECHANISMS 247tramition state (66) than through the boat-like six-centre alternative (67) .lolThis conformational preference, which is small, has been rationalised onthe basis of molecular-orbital symmetry relationships.lo2 It has also beenpredicted 102 that the 5,5-sigmatropic shift of a cis,cis-decatetraene willoccur most readily through a chair-like transition state (68).A chair-liketransition state seems also favoured in the Claisen rearrangement, althoughthe evidence here is less definitive.103 On heating the ketone (69) to 110"for 5 min., (70) is formed as an intermediate which is stable at room tem-perature; in the presence of dilute acid or base, however, aromatisation to0 2Me I! ' But (70)the thermodynamically more stable phenol (7 1) occurs instantaneously. Ifregarded as the penultimate step of a para Claisen rearrangement, then theconversion of (69) into (70) appears to be the first example of such arearrangement, in which the final 1,5-hydrogen shift occurs more slowlythan the preceding 3,3-sigmatropic shift .lo* Presumably, steric repulsionbetween the adjacent ally1 and t-butyl groups in (71) raises the barrier ofthe transition state leading to compound (71).Penta-l,4-dien-3-~1 vinyl ether (72) rearranges to the aldehyde (73)below room temperature in a remarkably ready reaction.105 3,S-Sigmatropicshifts which are facilitated by cyclopropane ring-opening are now welldocumented.Compound (74) is the first cis-1,2-divinylcyclopropane deriva-tive that has been isolated; it rearranges readily to bicyclo[3,2, lloctadienelol W. von E. Doering and W. R. Roth, Tetrahedron, 1962, 18, 67; Angew. Chem.,1963, 75, 27.loa R. Hoffmann and R. B. Woodward, J . Amer. Chem. SOC., 1966, 87, 4389; seealso K.Fukui and H. Fujimoto, Tetrahedron Letters, 1966, 261.lo3 E. N. Marvell, J. L. Stephenson, and J. Ong, J . Amer. Chem. SOC., 1965, 87,1267; for further studies of the Claisen rearrangement, see E. N. Marvell, B. J. Burreson,and T. Crandell, J . Org. Chem., 1965,30, 1030; E. N. Marvell, B. Richardson, R. Ander-son, J. L. Stephenson, and T. Crandell, ibid., p. 1032; H. L. Goering and W. I. Kimoto,J . Amr. Chem. Soc., 1965, 87, 1748.lo* B. Miller, J . Anaer. Chem. SOC., 1965, 8'4, 5515.lo6 S. F. Reed, jun., J . Org. Chem., 1965, 80, 1663248 ORGANIC CHEMISTRY(74a) as expected.lo6 A full paper has appeared on the related rearrange-ments of 2-alkenylcyclopropyl isocyanates ; lo7 similarly, double ScW-bases(75) rearrange to (76) on heating.108For 1 ,+sigmatropic shifts, two different transition-state geometries havebeen envisaged: in the suprufaciaE route " the migrating atom is associateda t all times with the same face of the n-system; in the second, anturafacialprocess the migrating atom is passed from the top face of one carbonterminus t o the bottom of the other." The reader is referred to the originalpaper 100 for a summary of symmetry-allowed 1,j-sigmatropic shifts and anabstract of literature results.The homovariant to 1 ,&hydrogen shifts, which is well established formedium-sized rings, has now been observed in acyclic compounds als0.~0~The most simple system is cis-hexa-1,4-diene (77), which on heating to 400"isomerises to (79); a rapid pre-equilibrium of (77) and (78) a t somewhatlower temperature is followed by irreversible formation of the product(79) .lo9 A similar hydrogen shift has been reported for allylacetophenone,which reacts in its enol form (80); this shift represents one step of analiphatic analogue to the '' abnormal Claisen rearrangement ." 110 Deriva-bives of cyclopropylacetic acid undergo decarboxylative ring-opening (81 ) ;e.g., above its melting point compound (82) is converted into (83) withintroduction of an angular methyl group.lllSince a direct 1,3-shift has been ruled out as a sequel to the nitrous aciddeamination of n-propylamine28 and is also unlikely to be involved in the6,2-migration of hydrogen in the norbornyl there is now, to theknowledge of the writer, no established example of a thermal urmtulysed1,3-sigmatropic shift within carbonium ions.l12 Therefore, a number oflo6 J.M. Brown, Chem. Comm., 1965, 226 [structure (111) in this paper should beidentical to (74a)l; see also P. K. Freeman and K. G. Kuper, Chem. and Ind., 1965,424.lo' E. Vogel, R. Erb, G. Lenz, and A. A. Bothner-By, Annulen, 1965, 682, 1.lo* H. A. Staab and F. Vogtle, Chm. Ber., 1965, 98,2681, 2691, 2701; H. A. StaabloS W. R. Roth and J. Konig, Annulen, 1965, 688, 28.R. M. Roberts, R. N. Greene, R. G. Landolt, and E. W. Heyer, J . Amer. Chem.ll1 T. Hanafusa, L. Birladeenu, and S. Winstein, J. Amer. C'hem. SOC., 1965, 87,112 For a catalysed 1,5-intramolecular hydride shift, see R. K. Hill and R. M. Carlson,and C. Wunsche, ibid., p.3479.Soc.. 1965, 87, 2282.3510; see also J. J. Sims, ibid., p. 3511.J. Amer. Chem. Xoc., 1965, 87, 2772CHALLIS : R E A C T I O N MECHANISMS 249reports (quoted in ref. 8) which have suggested this type of rearrangement,need further checking. Intramolecular 1,3-shifts within carbonium ionshave occasionally been proposed for the Jacobsen rearrangement 113 also.Part (ii). By B. C. Challis(Department of Chemistry, St. Salvator’s College, St. Andrews, Fife)Acidity Functions.-This topic was last reported in 1961.l Recentreviews cover investigations up until 1963 and therefore only developmentsof the last two years will be reported here.There can be no doubt that the acidity dependence of protonationequilibria for indicators of the same charge type also depends on theirspecific structure. This has led to a proliferation of acidity functions,particularly for acidic solvents, and those for amide (HA),3 indole (HI),*tertiary amine (H;”),5 and azulene (HAz) 6 indicators have been measuredand are different from H o and HR (GJ,,) values in the same solutions.Values of H , have been redetermined for perchloricusing only primary arrine indicators, and also for several other acidicsystem^.^ Considerable attention has been paid to reasons for the differentbehaviour of the various indicators: 3, 10 solvation of the conjugate acidappears to be a dominant factor and, generally speaking, the larger thenumber of acidic protons available for solvation, the smaller is the acidityfunction for a given acidity.Also, the effect of neutral salts on the H ,function can be closely predicted from their concomitant effect on aHz0.l1Other unknown factors must also be important, as is evident from reportsthat protonation of pyridine and pyridine l-oxide l2 both closely follow H ,and that the acidity-function values for secondary amides are larger thanthose for their tertiary c~unterparts.~a However, solvation effects appearto be least for the ionization of triphenylmethanol indicators 10, 13 and itwould therefore seem that, currently, the HR function (based on t,heseindicators) represents the best available approximation to the variation ofaH+ with stoicheiometric acidity. Similar arguments can be advanced113 References may be traced through a paper by E.N. Marvel1 and B. M. Graybill,J . Org. Chem., 1965, 30, 4014.J. H. Ridd, Ann. Reports, 1961, 58, 153.J. T. Edwards, Trans. Roy. SOC. Canada, 1964, 2, 313; E. M. Arnett, ProgPhys. Org. Chem., 1963, 1, 223.( a ) K. Yates and J. B. Stevens, Canad. J . Chem., 1965, 43, 529; ( b ) K. Yatesand J. C. Riordan, ibid., p. 2328; (c) K. Yates, J. B. Stevens, and A. R. Katritzky,ihid., 1964, 42, 1957; ( d ) R. B. Homer and R. B. Moodie, J . Chem. SOC., 1965, 4399.R. L. Hinman and J. Lang, J . Amer. Chem. SOC., 1964, 86, 3796.E. M. Arnett and G. W. Mach, J . Amer. Chenz. SOC., 1964, 86, 2671.F. A. Long and J. Schulze, J . Amer. Chem. SOC., 1964, 86, 337.&I. J. Jorgenson and D. R. Hartter, J . Amer. Chem. SOC., 1963, 85, 878.J. G. Dawber, J .Chem. SOC., 1965,4111; W. J. Zajac and R. B. Pu’owicki, J . Phys.Chem., 1965, 69, 2649; A. I. Gel’bshtein, R. P. Airapetova, G. G. Shchelova, and M. 1.Temkin, Zhur. neorg. Khim., 1964, 9, 1502; E. M. Arnett and C. F. Douty, J . Amer.Chem. SOC., 1964, 86, 409.lo E. M. Arnett and R. D. Bushick, J . Amer. Chem. SOC., 1964, 86, 1564.l1 C. Perrin, J . Amer. Chem. SOC., 1964, 86, 256.l2 C. D. Johnson, A. R. Ihtritzky, B. J. Ridgewell, N. Shakir, and A. M. White.Tetrahedron, 1965, 21, 1055.l3 E. D. Jensen and R. W. Taft, J . Amer. Client. SOC., 1964, 86, 116.and sulphuric acids’ K. Yates and H. Wai, J . Anaer. Chem. SOC., 1964, 86, 5409.250 ORGANIC CHEMISTRYfavouring the HR’ and HAZ functions, but data on these are a t presentincomplete.As a consequence of this strong dependence of equilibrium protonationon molecular structure, Kresge and his co-workers l4 have pointed out thatdifferent kinetic acidity dependence can be consistent with a single mechan-ism, if changes in reaction rate for different substrates are correlated witha single acidity function.Although Bunnett and Olsen l5 have shown howchanges in rate or equilibrium can be treated by means of linear free-energyrelationships, their treatment still requires an understanding of why somecompounds protonate in accordance with H , and others do not, before itcan be used as a mechanistic criterion. It therefore seems that acidity-function correlations must be interpreted with caution unt,il a clearer under-standing of protonation phenomena is available.Measurements of the H - function in several basic media have beenreported16 and in a t least one instance this function is dependent on theindicator, being different for amines 16b and substituted phenols.lGa Thisdifference, however, is less marked than that not’ed above for acidic solutions.As reported last year, several potential indicators, mainly polynitro-aromaticcompounds, complex with the lyate ion in basic solutions rather thanundergoing simple ionisation.17 The formation and structure of theseMeisenheimer complexes,ls and also the related Janovsky[lsb3 91 complexesformed with ketonic anions, have been studied further with an emphasison structural and mechanistic implications.The ionisation of 2,4-dinitro-aniline and the addition of methoxide ion to 2,4-dinitroanisole in methanoliesodium methoxide have been correlated with the H - and J- functions.16bSeveral reactions have been studied recently, involving nucleophilicdisplacement of a substituent by methoxide ion.20 These are thought tobe Bl reactions involving rapid formation of an intermediate (l), followedby slow elimination of the substituent.The reaction rates correlate withMe0 Ythe H - function; however, to a first approximation a t least, the concentra-tion of the intermediate should be proportional to the J , function. Ittherefore seems that the same problems confront kinetic acidity-functioncorrelations in basic media as those noted by Kresge and his co-workersl4 A. J. Kresge, R.A. More 0’ Ferrall, L. E. Hakka, and V. P. Vitullo, Chem. Cmm.,1965, 47.l5 6. F. Bunnett and F. P. Olsen, Chenz. Contm., 1965, 601.l6 ( a ) C. H. Rochester, J . Chem. Soc., 1965, 676; ( b ) C. H. Rochester, ibid., p. 2404;( c ) K. Bowden, Canad. J . Chem., 1965, 43, 2624; ( d ) R. Stewart and J. P. O’Donnell,ibid., 1964,42, 1681; ( e ) K. Bowden and R. Stewart, Tetrahedron, 1965,21,261; (f) V. I.Lazarev and Yu. V. Moiseev, Zhur. Jiz. Khirn., 1965, 39, 445.l7 B. Capon and C . W. Rees, Ann. Reports, 1964, 61, 277.l6 (a) M. R. Crampton and V. Gold, Chenz. Comm., 1965, 256; ( b ) R. Foster andIs R. J. Pollitt and B. C. Saunders, J. Chem. SOC., 1965, 4615.2o F. Terrier, Compt. Tend., 1965, 261, 1001; R. Schaal and J.-C. Latour, Bull.C . A. Fife, Tetrahedron, 1965, 21, 3363.SOC.chim. France, 1964, 2 177CHALLIS : REACTION MECHANISMS 251under acid conditions.14 Measurements of the strength of several extremelyweak organic acids, up to pK, = 34, have been possible with the availabilityof strongly basic media.16e, 21Deuterium-isotope Eff ects.-These are conveniently discussed under threesub-headings : primary effects in reactions where the isotopically substitutedbond undergoes fission ; secondary effects associated with isotopic substitu-tion in a bond not undergoing fission; and solvent effects arising fromdifferences between water and deuterium oxide as reaction media. Generalaspects of the subject have been discussed from the standpoint of usingstatistical-mechanical calculations to predict both kinetic and equilibriumisotope ratios,22 and Bourns 23 has reviewed kinetic isotope effects in electro-philic aromatic substitution.Primary isotope eflects.The interpretation of low k d k D ratios hasbeen discussed by Bell.24 Although evidence from the ionisation rates ofpseudo-acids indicates that the k d k D ratio varies with the symmetry ofthe transition 25 as suggested by Westheimer,26 other factors, in-cluding bending vibrations and non-equilibrium solvation of the transitionstate, can reduce the isotope effect. Proton tunnelling is thought 24 to beless important than suggested by earlier calculations, Nevertheless, interestcontinues in possible contributions from this source and barrier dimensionsfor several reactions thought to involve tunnelling have been compared.27The Arrhenius parameters for proton abstraction from both di-jsopropyllcetone28 and acetone 29a are quite normal and independent of isotopicsubstitution; thus the curved Arrhenius plots observed for these reac-tions 2 8 y 29 probably arise from steric or medium effects rather than fromnon- classical behaviour.The Arrhenius plot for acetone is apparently quitelinear a t higher temperature^.^^ Swain and his co-workers 31 have marshalledarguments against any primary isotope effect for proton transfers from oneoxygen (or nitrogen) to another, accompanying cleavage of a carbon bond,as in the cyclisation of chlorohydrins (see below). These arguments probablyaccount for the absence of an isotope effect in the thermal decarboxylationof malonic acid,38 hitherto expected on the basis of a cyclic intermediate.Secondary isotope eflects.As is evident from Halevi’s 33 excellent reviewof this subject, several factors influence these effects, depending on theposition of isotopic substitution and the kind of reaction. The n.m.r.21 E. C. Steiner and J. M. Gilbert, J. Amer. Chern. SOC., 1965,87,382; A. Straitwieser,J. I. Braumn, J. H. Hammons, and A. H. Pudjaatmaka, ibid., p. 384.22 M. J. Stern and M. Wolfsberg, J. Pharm. Sci., 1965, 54, 849; cf. M. Wolfsbergand M. J. Stern, Pure Appl. Chem., 1964, 8, 225.23A. N. Bourns, Trans. Roy. SOC. Canada, 1964, 2, 277.2 4 R. P. Bell, Discuss. Faraday SOC., 1965, 39, 16.25 R. P. Bell and J. E. Crooks, Proc.Roy. SOC., 1965, A, 286, 285.26 F. H. Westheimer, Chem. Rev., 1961, 61, 265; cf. J. Bigeliesen, Pure Appl,2 7 E. F. Caldin and M. Kasparian, Discuss. Farday SOC., 1965, 39, 25.28 J. R. Jones, Trans. Faraday SOC., 1965, 61, 2456.29 J. R. Hulett, J. Chern. SOC., 1965, ( a ) p. 1166; ( b ) p. 430.30 J. R. Jones, Trans. Faraday SOC., 1965, 61, 95.31 C. G. Swain, D. A. Kuhn, and R. L. Schowen, J . Amer. Chem. SOC., 1965, 87,82A. T. Blades and M. G. H. Wallbridge, J . Chem. Soc., 1965, 792.33 E. A. Halevi, Prog. Phys. Org. Chem., 1963, 1, 109.Chern., 1964, 8, 217.1553252 ORGANIC CHEMISTRYproton shifts induced by a-deuteration of butan-2-ones 34 and the effect ofdeuterium substitution on the stability of silver ion-olefin complexes 35sustain arguments for greater inductive electron donation by deuterium.However, the Taft 19F chemical shifts for m- and p-fluorotoluene indicatethat the inductive effect of the methyl group is not altered by deuterationand that the resonance effect decreases by only one-tenth of that predictedby chemical studies.36 There have been more reports 37 of appreciable ratereductions (about 12% per D atom) accompanying a-deuteration in limiting(SN1) solvolysis reactions.The exact cause of these reductions is still notclear,38 although further evidence of their diminution by neighbouring-group participation,39 and in direct displacement (&2) reactions,4* supportsthe working hypothesis advanced earlier by Streit~ieser.~l On the otherhand, Wu and Robertson’s 42 recent finding that the a-deuterium isotopeeffect in displacement reactions of trimethylsulphonium ion changes from“ normal ” (EH/kD > 1) to “ inverse ” with only modest increase in thenucleophilicity of the reagent suggests other factors may be involved.Rate retardations arising from /?-deuteration have frequently beenattributed to the larger hyperconjugative release of electrons by hydrogen.However, participation by trans-p-hydrogen in the form of a non-classicalunsymmetrically hydrogen- bridged ion rather than simple hyperconj ugationis suggested by Shiner a,nd Jewett 43a to explain the large but non-cumulativeeffects of 2- and 6-deuteration in the acetolysis of cis-4-t-butylcyclohexylp-bromobenzenesulphonate (2).The effects of B-deuteration on the solvo-OBslysis of the corresponding trans-isomer (3) 43b and the cyclohexyl toluene-p-sulphonates 44 have been interpreted as evidence for a skew-boat ratherthan a chair transition state.The absence of appreciable /?-deuteriumeffects in the SNl solvolysis of several cyclopropyl and cyclobutyl saltssuggests reaction via non-classical carbonium ions in which hyperconjugativeeffects are minimi~ed.~~s4 0. S. Tee and J. Warkentin, Canad. J. Chem., 1965, 43, 2424.35 R. J. Cvetanovid, F. J. Duncan, W. E. Falconer, and R. S. Irwin, J. Amr. Chetn.36 D. D. Traficante and G. E. Maciel, J. Amer. Chem. Soc., 1965, 87, 4917, 2508.s 7 V. Belanid-Lipovac, S. Bordid, and D. E. Sunko, Croat. Chem. Acta, 1965, 37,61; C. C. Lee and E. W. C.Wong, Canad. J. Chenz., 1965, 43, 2254; A. Streitwieser andH. S. Klein, J. Arner. Chem. SOC., 1964, 86, 5170.38P. Geneste and G. Lamaty, Tetrahedron Letters, 1965, 4633.39 C. C. Lee and E. W. C. Wong, Tetrahedron, 1965, 21, 539; J. P. Schaefer and40 B. btman, J. Am;; Chem. Soc., 1965, 87, 3163.Solvolytic Displacement Reactions,” McGraw-Hill, New4 2 C. Y. Wu and R. E. Robertson, Chem. and lnd., 1964, 1803.43V. J. Shiner and J. G. Jewett, J. Amer. Chem. SOC., 1965, 87, ( a ) p. 1382; (b)44 W. H. Srtunders and K. T. Findley, J . Amer. Chem. SOC., 1965, 87, 1384.45 M. Nikoletid, S. BorEid, and D. E. Sunko, Proc. Nut. Acad. Sci. U.S.A., 1964,Soc., 1965, 87, 1827.D. S. Weinberg, Tetrahedron Letters, 1965, 2491.York, 1962, p. 172.Cf. A. Streitwieser,p. 1383.52, 893CHALLIS : REACTION MECHANISMS 253Further temperature-independent p-deuterium-isotope effects have beenreported.46 In one case 46a these are viewed as additipid evidence for theimportance of non- bonded interactions arising frQm different potentialbarriers for the rotation of CH, and CD, greaps.However, the verydifferent behaviour of isopropyl47 and t-butyl salts 48 is difficult to accountfor in this way.48 An alternative explanation, proffered recently by Wolfs-berg and is that temperature independence arises from a fortuitouscancellation of zero-point energy differences. Whether secondary isotopeeffects are temperature-dependent or not may be a criterion for themechanism of solvolyses.48Secondary isotope effects have proved particularly useful in elucidatingthe mechanism of N-nitration 50 and of the Diels-Alder reaction.51Solvent isotope e#ects.The importance of initial rather than transition-state solvation in determining solvent isotope ratios in solvolyses continuesto be debated, and Laughton and Robertson52 have replied to recentcriticism of their arguments for this effect. Other evidence53 also showsthat a t least part of the activation energy in tertiary halide solvolysis isrequired to break down the initial solvent shell. On the other hand, Swainand his co-workers 31 have concluded that differences in transifion-statesolvation can fully account for the kinetic solvent isotope effects in a numberof cyclisations. A simple method of calculating these effects is given andsome mechanistic implications are discussed.Despite some evidence suggesting that in protein synthesis m-RNA is readfrom the 3’-hydroxyl to the 5’hydroxyl end,65 very clear-cut experimentsnow indicate that it is read from the 5’-end.6s, 67 For example,66 poly-nucleotides of the type ApApAp . .. pApApC with about twenty nucleotideresidues, directed the synthesis of a group of peptides of varying chain-lengthcontaining lysine (the codon for which is AAA) and one asparagine (codon,AAC), which was carboxyl-terminal, Le., lys-(lys),-aspN. Hence, if thepolypeptide is assembled from the amino- to the carboxyl-terminal end, thepolynucleotide message must be read from the 5’- to the 3‘-hydroxyl end.A study of the direction of chain growth in enzymatic RNA synthesis fromthe nucleoside 5‘-triphosphate with RNA polymerase has shown unequi-vocally that it also proceeds from tthe 5’- to the 3‘-end.@It has been known for some time that streptomycin interferes withprotein synthesis in some way.69 It has now been found 70 that this anti-biotic has an effect on the m-RNA-ribosome-aminoacyl-s-RNA complex.The coding ambiguity observed in the presence of streptomycin with poly U(which then directs the incorporation of ileu in addition to the normal phe)is explained by the finding that the binding of phe-s-RNA to the complex isinhibited, whereas the binding of ileu-s-RNA is stimulated by streptomycin.Work has continued on natural m-R,NA itself.The thread of RNA whichconnects the ribosomes in reticulocyte polysomes has been isolated.It hasa molecular-weight of about 150,000, which is the size predicted for messen-gers for each hsmoglobin chain if the messengers are monoci~tronic,~~ i.e.,if each in-RNA makes one protein. The isolation of an m-RNA of about36 nucleotide residues for Gramicidin S synthesis has been reported.72 Thisantibiotic contains 10 amino-acids. Determination of the m-RNA sequenceshould indicate whether initiation and termination codons exist. Work onpure species of RNA should be aided by the discovery that superior frac-tionation is achieved in a sucrose gradient in a zonal ultracentrif~ge.~~ The invitro synthesis of infectious bacteriophage (bacterial virus) RNA, using isolatednatural m-RNA and the appropriate enzymes, provides a clear demonstrationof the correctness of current ideas regarding nucleic acid metabolism.7*Secondary Structure.-Of crucial importance to an understanding of themechanism of metabolic reactions involving nucleic acids is knowledge oftheir secondary structure. All the evidence regarding the secondary struc-ture of s-RNA mentioned in a previous report 75 has proved to be wrong.Thus, the ‘‘ crystalline s-RNA ” whose structure was investigated by X-raycrystallography has now been found to have consisted of degraded P R N A , ~ ~and the idea that the minor constituents of s-RNA (methylated bases,pseudouridine, etc.) are concentrated in a centra.1 region is not supported bythe sequence studies mentioned above.48, 54 s-RNA and r-RNA are knownto consist of single polynucleotide chains.Most of the evidence previouslyadvanced in favour of the existence of double-helical regions in these rnole-cules (by the molecule folding back onto itself) has since been shown to beambiguous (see below), and a t present the secondary structure of thesesubstances is quite uncertain. Holley’s structure far alanine s-RNA does notpermit extensive base-pairing t o form double- helical regions.Closely related to the question of the nature of the secondary structureitself is a consideration of the stability of helical forms. Ideas concerningthe factors stabilising helical polynucleotides have undergone a radicalchange in recent years. It was originally supposed that the specific hydrogenbonds between the heterocyclic bases was responsible for the stability of theDNA double helix, and this was apparently confirmed by the fact that, thehigher the GC content, the more stable the DNA (sincs the GC pair can formthree hydrogen bonds, and the AT pair only two).Considerable evidenceindicates, however, that hydrogen-bonding cannot account for the stabilityof helical DNA. For example, classical hydrogen- bond breaking agentssuch as urea are relatively ineffective in denaturing DNA. [Denaturation ofdouble-helical DNA involves two processes: ( 1 ) separation of the strands,and (2) helix+coil transition in the separated strands]. Much more effective71A. Burmy and G. Marbaix, Biochem. Biophys. Acta, 1965, 103, 409.74 J.B. Hall, J. W. Sedat, P. R. Adiga, I. Uemara, and T. Winnick, J. Mol. BioZ.,73 J. R. B. Hastings, J. H. Parish, K. S. Kirby, and E. S. Klucis, Nature, 1965,7 4 S . Spiegelman, I. Haruna, I. B. Holland, G. Beaudreau, and D. Mills, Proc.75 T. L. V. Ulbricht, Ann. Reporh, 1963, 59, 378.7 6 M. Spencer and F. Poole, J. Mot. Biol.. 1965, 11, 314.1965, 12, 162; 5. W. Sedat and J. B. Hall, ibid., p. 174.208, 645.Nut. Acad. Sci., U.S.A., 1965, 54, 91941 2 ORGANIC CHEMISTRYare certain anions, such as C104-, which alter the structure of water and whichare regarded as hydrophobic bond breaking agents.77 (The concept ‘‘ hydro-phobic bond,” which originated in protein chemistry, means in this instancethat the attraction of the bases for each other is greater than their attractionfor water molecules).That the main factor stabilising helical polynucleo-tides is interaction between the bases stacked parallel on top of each otheris also supported by recent theoretical studies.78The mast important recent evidence regarding secondary structure andhelix stability has come from a study of oligo- and poly-nucleotides usingoptical rotatory dispersion (0.r.d.). In the course of the last year this tech-nique has become much more widely used in this field, and significantadvances have been made in interpretation. On comparing a mononu-cleotide with its oligo- and poly-nucleotide homologues, the biggest changein the 0.r.d. is found on going from the monomer to the dimer.T9, 8 0 Tinocoand co-workers 80 calculated that the interaction between the two bases indiadenylic acid leads to a splitting of the adenine 260 mp absorption band.The two bands thus produced must have Cotton effects (C.E.s) of oppositesign and of approximately equal magnitude.The troughs of the twoC.E.s overlap, leading to the observed curve, which consists of twopeaks and a trough, the latter being near the U.V. absorption maximum.What is striking is the close resemblance of the overall shape of the 0.r.d.curves of simple dinucleotides to the curves given by DNA and RNA,81 andhomologous polynucleotides,~2-84 which all give two peaks and a trough inthe 230-290 mp region, with the exception of poly I, which gives two troughsand one peak.84 An examination of a wide variety of di- and tri-nucleotides 85has indicated that the shape of the 0.r.d.curves depends not only on basecomposition but also on base sequence.The effect of chain-length on secondary structure and helix stability hasbeen studied by comparing the physical properties of a series of oligoadenylicacids. The results using o.r.d.86 and circular dichroism 87 complement eachother. They confirm previous work which indicated that poly A has a single-stranded helical structure at neutral pH 81, 82 and a double-stranded structureat acid pH (<5). The mean residue amplitude of the first C.E. increasesgradually with chain-length at neutral pH, levelling off and reaching amaximum at about 30 residues, whereas in acid there is a transition at about77 K. Hamaguchi and E. P.Geidushek, J. Arner. Chem. SOC., 1962, 84, 1329.78H. DeVoe and I. Tinoco, jun., J. MoZ. Biol., 1962, 4, 500; 0. Sinanoglu andS. Abdulnur, Photochem. Photobwl., 1964, 3, 333; D. M. Crothers and B. H. Zimm,J. Mol. Biol., 1964, 9, 1.7 9 T. R. Emerson, R. J. Swan, A. M. Michelson, and T. L. V. Ulbricht, AbstractsFed. Europ. Biochem. SOC., 1965, e 59.M. W. Warshaw, C. A. Bush, and I. Tinoco, jm., Biochem. Biophys. Res. Comm.,1965, 18, 633.81 T. Samejima and J. T. Yang, J . BioZ. Chem., 1965, 240, 2094.8 2 G. D. Fasman, C. Lindblow, and L. Grossman, Biochemistry, 1964, 3, 1015.83P. K. Sarkar and J. T. Yang, J. Biol. Chem., 1965, 240, 2099.K. Sarkar and J. T. Yang, Biochemistry, 1965, 4, 1238.s 5 M. W. Warshaw and I. Tinoco, jun., J.MoZ. Biol., 1965, 13, 54; C. R. Cantor86 A. M. Michelson, T. L. V. Ulbricht, T. R. Emerson, and R. J. Swan, Nature,87 J. Brahms, A. M. Michelson, and K. E. Van Holde, J. MoZ. Biol., 1966, 15, 467.and I. Tinoco, jun., ibid., 1965, 13, 65.1966, 209, 873ULBRICHT: NUCLEIC ACIDS 4137 residues (pH 4.5) or 12 residues (pH 4.86) to the double-stranded structure,with a further marked increase in rotation.88, 87 Optical rotatory dispersionstudies have also confirmed that poly C exists as a single-stranded helix atneutralPoly G has been synthesised enzymatically a t l a ~ t . 8 ~ It forms a 1 : 1complex with poly C which is very stable;g0 the extent of the interactionbetween the two polynucleotide strands a t different pH values is shown veryclearly by the changes in ~ .r . d . ~ l The 0.r.d. of yeast s-RNA indicates that ithas a highly ordered secondary structure which is probably Addi-tion of ethylene glycol to the solution causes a loss of secondary structure.Since ethylene glycol stabilises helices held together by hydrogen- bondingbut decreases hydrophobic interactions, the latter are responsible for thesecondary structure of S-RNA.~~ This is in agreement with the structure ofalanine s-RNA and is in marked contrast to models of s-RNA with over80 o/o of ba~e-pairing.~~If the stability of helical polynucleotides is mainly due to base interaction,why is helix stability related to GC content? It has been shown that, of thefour RNA bases, U interacts least strongly with its neighbour~.~~ Conse-quently, the DNA with the lowest T content (since T is very similar to V),that is, the highest GC content, should be the most stable, as found.More-over, this should be measurable by the amplitude of the first Cotton effect(the size of which seems to be closely related to the extent of base-interac-tion) and, indeed, there is a linear correlation between the molecular rotationat the 290 mp. peak of DNA and GC content.a1The denaturation of single-stranded helical polynucleatides (such aspolp A, poly C ) is accompanied by a hyperchromic effect and a reduction inrotation, just as is the denaturation af double helical DNA. Similar changesaccompanying the denaturation of RNA used to be interpreted as being dueto the separation of double-helical regions of the molecule, but it is clear thatthese changes indicate a helix-+coil transition but do not in themselvesindicate whether the helix is single- or double-stranded.This explains thepresent uncertainty regarding the secondary structure of s-RNA.A thorough examination of the 0.r.d. of a large number of nucleosideshas made it possible to correlate the sign and magnitude of the C.E. with theconformation of nucleosides in solution. 94 These studies indicate that thepreferred conformation is the same as that found in DNA and in crystallinenucleosides. 9588 V. Luzzati, A. Mathis, F. Masson, and J. Witz, J. 1clol. Biol., 1964, 10, 28;J. Witz and V. Luzzati, ibid., 1965, 11, 620; D. N. Holcomb and I. Tinoco, &n., Bio-polymers, 1965, 3, 121; K.E. van Holde, J. Brahms, and A. M. Michelson, J. Mol.Biol., 1965, 12, 726.s9 M. N. Thang, $1. Graffe, and 3%. Grunberg-Manago, Biochirn. Biopl~ys. Acta,1965, 108, 125.F. %chon and A. M. Michelson, Proc. iVat. Acad. Sci., U.S.A., 1965, 53, 1425.91 T. L. V. Ulbricht, R. J. Swan, and A. M. Michelson, Chem. Comni., 1966, 63.92 G. D. Fasman, C. Lindblow, and E. Seaman, J. Mol. Biol., 1965, 12, 630.O3 G. Felsenfeld and G. Sandeen, J. Mol. Biol., 1962, 5, 587; G. Falsenfeld and G. L.Cantor, Proc. Nut. Acad. Xci., U.S.A., 1964,51,518; S. W. Englander and J. J. Englander,ibid., 1965, 370.BP T. L. V. Ulbricht, T. R. Emerson, and R. J. Swan, Biochena. Biophys. Res. Conam.,1965, 19, 643.95 M. Sundaralingam and L. H. Jensen, J. Mol.Biol., 1966, 13, 914, 93013. BIOSYNTHESISBy G). W. Kirby(Department of Chemistry, Imperial College, London, S. W.7)IN recent years organic chemists have shown increasing interest in the experi-mental investigation of natural product biosynthesis. Particular attentionhas been paid to the complex ‘‘ secondary metabolites ” produced by plantsand, to a lesser extent, by animals. Many earlier biogenetic theories havenow been verified and extended by in, vivo experiments with labelledprecursors. For reasons of space the present report must be highly selective.Emphasis is placed on experimental work with compounds of special interestto the organic chemist. Topics have been chosen to illustrate, as far as pos-sible, the scope of current investigations.Aromatic Alkaloids.-.IndoZe alkaloids.It is well established that theindolylethane unit of alkaloids such as vindoline (1) is derived biologicallyfrom trypt~phan.~ At the beginning of 1965 the origin of the remainingb(4)A R. ..II (3) **IJ. D. Bu’Lock, “ The Biosynthesis of ?tural Products,” McGraw-Hill, London,1965; J. H. Richards and J. B. Hendrickson, The Biosynthesis of Steroids, Terpenes,and Acetogenins,” Benjamin, New York, 1964; “ Biogenesis of Natural Compounds,”ed. P. Bernfeld, Pergamon Press, Oxford, 1963.R. Robinson, “ The Structural Relations of Natural Products,” Clarendon Press,Oxford, 1955.E. Leete, A. Ahmad, and I. Kompis, J . Amer. Chem. SOC., 1965, 87, 4168, andreferences citedKIRBY: BIOSYNTHESIS 415Cl0 (or C,) fragment of the indole alkaloids was still obscure.Leete and hiscolleagues had earlier presented evidence that this fragment was constructedfrom acetic and malonic acids together with a C,-unit derived from formate.However, more recent work from three other laboratories cast doubt on thishypothesis which has now been withdrawal During the last few monthsconvincing proof of the terpenoid origin of the C,, fragment has appeared.Scott and his colleagues 5 showed that [2-14C]mevalonic lactone (2) servedas a precursor for vindoline (1) in Catharanthw roseus (Vinca rosea). De-gradation established that 22.0% of the total activity was at C-22. Inde-pendent studies by Goeggel and Arigoni,6 with the same plant, gave essen-tially the same result. Clearly mevalonate, unlike acetate and formate: wasincorporated in a specific manner into the alkaloid, approximately one quar-ter of the activity appearing in one carbon atom.These results are consistentwith a hypothesis developed independently by Thomas and Wenkert,'i.e., that mevalonate is converted into a monoterpenoid derivative (3),which can give rise to the typical indole alkaloid fragments (4), ( 5 ) , and (6).To explain the labelling pattern in vindoline the methyl carbons of theisopropylidene groups in (3) must become equivalent a t some stage in thebiosynthesis and thus each acquire, effectively, one quarter of the totalactivity. Excellent precedence for this is available from the work by Yeowelland Schmid 8 on the monoterpenoid plumiericin.The unrearranged fragment (4) is present in many indole alkaloids.Goeggel and Arigoni showed 6 that reserpinine (7), a representative of thisclass, was derived from [ 2-WJmevalonate.Again, approximately onequarter (26%) of the activity was present in one carbon atom [as (7)].Recent independent studies by Battersby and his colleagues have confirmedand extended these findings. Their experiments with Rhuzia strictct provedespecially fruitful. [ 2-14C]Mevalonate was incorporated into dehydroaspi-dospermidine (8) and degradation located two-thirds (65 & 6%) of theactivity at C-8. Since a labelled carbon atom (originally attached to (2-3) islost during the biosynthesis of this alkaloid, their result is in completeagreement with theory.Further support came from the degradation ofdehydroaspidospermidine derived from [ 3-14C)mevalonate : approximatelyhalf the alkaloid's activitywas found at C-20. This group further showed thatcatharanthine (9), which contains the hypothetical fragment (6), is alsoderived from [2-14C]mevalonate in the predicted manner.BenzyZisoquinoZine group. Full details have appeared 1 0 of work by two*A. R. Battersby, R. Binks, W. Laurie, G. V. P q , and B. R. Webster, Proc.Chem. Soc., 1963, 369; H. Goeggel and D. Arigoni, Experientia, 1965, 21, 369; D. H. R.Barton, G. W. Kirby, R. H. Prager, and E. M. Wilson, J . Chem. Soc., 1965, 3990.T. Money, I. G. Wright, F. McCapra, and A. I. Scott, Proc. Nat. Acad. Sci.U.S.A., 1965, 53, 901; F. McCapra, T. Money, A.I. Scott, and I. G. Wright, Chem.Comm., 1965, 537.eH. Goeggel and D. Arigoni, Chem. C m m . , 1965, 538.R. Thomas, Tetrahedron Letters, 1961, 544; E. Wenkert, J . Amer. Chem. SOC.,1962, 84, 98.8D. A. Yeowell and H. Schmid, Experientia, 1964, 20, 250.* A . R. Battersby, R. T. Brown, R. S. Kapil, A. 0. Plunkett, and J. B. Taylor,Chem. Comm., 1966, 46.lo D. H. R. Barton, G. W. Kirby, W. Steglich, G. M. Thomas, A. R. Battersby,T. A. Dobson, and H. Ramuz, J . Chem. SOC., 1965, 2423416 ORGANIC CHEMISTRYgroups on the biosynthesis of the morphine alkaloids in Papaver somniferum.Feeding experiments with multiply-labelled precursors, supported by appro-priate degradations, established that reticuline (lo), salutaridine ( I 1 ), andone of the epimeric dienols (12), were incorporated intact into thebaine (13).All three methyl groups of reticuline were retained in the final alkaloid.Radio-dilution studies showed that salutaridine was a transient intermediatein the conversion of norlaudanosoline (trisnor-reticuline) or tyrosine into themorphine alkaloids.For stereochemical reasons ( - )-reticuline (10) mustbe the immediate precursor of the dienone (11). However, Battersby andhis colleages 11 have shown that both ( -)- and (+ )-reticuline are efficientprecursors of morphine. Incorporation of the ( +)-isomer, however, involvedconsiderable (though not complete) loss of tritium from material labelled asshown [asterisk in (lo)]. This is understandable if reticuline is racemised inthe plant vicc its 192-dehydro-derivative. A separate experiment confirmedthat lY2-dehydroreticuline was indeed efficiently converted into morphine.Moreover, partially racemic reticuline has now been isolated from opium.12OMeA preliminary account of work on the biosynthesis of sinomenine (14) inXinomenium acutum has appeared.13 The enantiomer of salutaridine (1 1 ),sinoacutine,l* labelled with tritium at position 1, was incorporated intosinomenine without “ scrambling ” of the label.( j-)-Reticuline was alsoincorporated, though much less efficiently.but not (-)-retidine, was a good precursor for berberine in Hydrastiscanadensis and for protopine in Bicentra spectabibis and Argzmone species.15Clearly, at least one step in the biosynthesis of these optically inactive mole-cules from reticuline must be stereospecific.Elegant experiments l7 withmultiply-labelled, optically active, specimens of reticuline have elucidatedthe main steps in the construction of protopine, stylopine (18), and cheli-donine (19) in Chebidoniurn majus. Again it was shown that (+)-reticulinewas the true precursor of all three alkaloids. Narcotine (20) can also beadded to the now extensive list of alkaloids derived from this versatileprecursor.l* Conversion of the simpler benzylisoquinoline ( + )-coclaurinelabelled with tritium as shown (21), into the correspondingly labelled dienone,crotonosine (22), has been observed l9 in Croton linearis. (-))-Coclaurineand isococlaurine [methoxyl and hydroxyl groups in ring A of (21) inter-changed] were not incorporated into crotonosine.Monkovi6 and Spenser 20have recently reported the specific incorporation of ( &)-noradrenaline intoberberastine (5-hydroxyberberine) in Hydrastis canadensis.An auspicious start to the study of aporphine biospthesis has been madeby Battersby and his colleagues.21 ( +)-Orientdine (23) was incorporatedinto isothebaine (24) in Papaver orientale. Again, experiments with doubly-labelled [see (23) and (24)] and optically active precursors established beyonddoubt that conversion had taken place in a specific manner. The overalltransformation, which proceeds via the dienone (25) and a correspondingdienol, has also been achieved chemically.Colchicine and phenethylisoquinoline alkaloids.It is well established thatthe entire carbon skeleton of colchicine (26) is derived from phenylalanine(C,-C, unit) and tyrosine (expanded C,-C, unit).22, 23 Leete has now re-ported 23 the specific incorporation of ( &)-[4-1PC]tyrosine (27) into colchi-cine in Colcchicum byxantinum, thus confirming the origin of the tropolonering. Battersby and Leete's results suggest therefore a biosynthetic inter-mediate of the type (28). The discovery 24 of a new alkaloid, androcymbineMe0Me0, <NM~Me0 "'"or>. , HMe0(29), from a botanically related plant, Androcyrnbium melanthiodes, providesstriking support for this idea. The same plant also contains melanthioidine,a bis-l-phenethylisoquinoline alkaloid :25 it appears then that colchicine maybe the first known member of an interesting new group of phenethyliso-quinoline derivatives.Pyridine and quinoline alkaloids.The biosynthesis of nicotine (30) hasbeen more intensively studied than that of any other alkaloid,26 but new22 A. R. Battersby, R. Binks, J. J. Reynolds, md D. A. Yeowell, J . Chem. SOC.,1964, 4257; R. D. Hill and A. M . Unrau, Canad. J . Chem., 1965, 43, 709.23 E. Leete, Tetrahedron Letters, 1963, 333.2 4 A. R. Battersby, R. B. Herbert, L. Pijewska, and F. gantavy, Chew. Cmnz.,25 A. R. Battersby, R. B. Herbert, and F. Santavy, Chem. Comm., 1965, 415.26 E. Leete, Science, 1965,147, 1000; E. Ramstad and S. Agurell, Ann. Rev. Plant.1965, 228.Physiol., 1964, 15, 143KIEBY: BIOSYNTHESIS 419results are still forthcoming.Experiments with whole tobacco plants(Nicotiana tizbacum L.) have demonstrated that quinolinic acid, like nicotinicacid, is an efficient precursor for the alkal~id.~' Thus [2,3,7,8-14C]quinolinicacid (31) was converted into nicotine which contained all its activity in thepy-ridine ring. A parallel experiment with [2,3,7-14C]nicotinic acid gaveradioactive nicotine, which was degraded t o establish the labelling pattern(30) expected from earlier work. Recent experiments by Rapoport and hiscolleagues28 concern the origin of the pyrrolidine ring. Nicotine, isolatedfrom Nicotiancr glutinosa plants which had been exposed to [14C]carbondioxide, was degraded to establish the activity at each carbon atom in thepyrrolidine ring. The activities at C-2', C-3', and C-5' were similar, but t'hatat C-4' was approximately 4 times a,s large.This result is inconsistent withI (32) ( 3 3 )the obligatory participation of a symmetrical intermediate [as (32)], derivedfrom acetate 29 or ornithine (33). The same group confirmed that ornit'hinewas incorporated in the usual way in N . gbutinosa, but concluded that theincorporation must involve a minor or '' aberrant " pathway.Preliminary studies 30 on the biosynthesis of a group of quinoline deriva-tives, (34; R = alkyl), from a Pseudomonas species, have been reported.[carb~xyl-~*C]Anthranilic acid was incorporated intact, and acetate appearedto be an efficient precursor for the fatty side chain, R. The alkaloid peganine(vasicine) (35) is also derived, in Adhctboda vmica, from [c~rboxyZ-~~CIanthra-nilic a~id.~1 Degradation of the labelled peganine gave a,nthranilic acid ofthe same molar activity.The biological conversion of shikimic and anthra-nilic acids into damascenine (36) has also been reported.32Lsoprenoids.-Valuable comprehensive reviews of steroid and terpenoidbiosynthesis have appeared.33 The stereochemistry of the reactions leadingfrom mevalonate t o squalene and other higher terpenoids is now understood27 K. S. Ymg, R. K. Gholson, and G. R. Wder, J . Amer. Chem. Soc., 1965, 87,28A. A. Liebmann, F. Morsingh, and H. Rapoport, J. Amer. Chem. Soc., 1965,28 P.-€3. L. Wu and R. V. Byerrum, Biochemistry, 1965, 4, 1628.30 M. Luckner and C. Ritter, Tetrahairon Letters, 1965, 741.31 D.Groger, S. Johne, and K. Mothes, Experientia, 1965,21,13; see also L. Skurskf,32 D. Munsche and I(. Mothes, PhytochRmistry, 1965, 4, 705.33 R. B. Clayton, &wart. Rev., 1965, 19, 168, 201; F. Lynen, Angew. Chem., 1965,4184; see also K. S . Yang and C. R. Waller, Phytochemistry, 1965, 4, 881.87, 4399.Coll. Czech. Chem. Comm., 1965, SO, 2080.77, 929; I(. Bloch, ibid., 1965, 77, 944420 ORGANIC CHEMISTRYin impressive detail (see p. 428). However, one investigation 34 stemmingfrom this stereochemical work will be outlined here. [4R-3H]Mevalonic acidwas mixed with [ 2-14C]mevalonic acid to give the doubly-labelled specimen(37). This was converted by a rat liver homogenate into lanosterol (38) andcholesterol (39) via squalene (40). Measurement of 3H : 14C ratios showedthat lanosterol and cholesterol retained respectively 5 and 3 of the 6 tritiumatoms in the intermediate squalene.Biological degradation of the labelledcholesterol revealed one tritium atom a t the l7a-position and left little doubtthat the remaining two were a t (3-20 and (3-24. The results were entirely ineHO( 3 9)AT I A’ OHagreement with the mechanism for squalene cyclisation proposed earlier.35Lederer and his colleagues have shown 36 that biological C-methylation withmethionine, for example in the biosynthesis of ergosterol in Neurosporacrassa, can involve loss of one hydrogen atom from the original S-methylgroup.A full account has appeared of the studies by Leete and his group on thebiosynthesis of digitoxigenin (41 ) in DigitaZis p~rpurea.~’ The labelledcardenolide (41) derived from [2J4C Jmevalonate (42) contained no activityin the butenolide ring [cf.the 14C labelling pattern in cholesterol (39)].Microbial degradation located radioactivity a t C-1, C-7, and C-15, showingthat the steroidal nucleus was constructed in the usual way. However, onethird of the activity derived from [3’-14C]mevalonate (42) was found a t C-21;also [1-14C]acetate gave material labelled at C-20 and (3-23 as well as atother positions in the nucleus. These results strongly suggest that thedigitoxigen is formed by the condensation of a C,, pregnane derivative withone molecule of acetic acid. Independent work by Tsche~che,~~ Rei~hstein,~~and their respective colleagues had led to the same conclusion. Tschescheand Brassat have now reported 40 related investigations on the bufadienolideglycoside, hellebrin (43), in Helleborus atrorubens.A5-Pregnen-3/l-ol-20-one,labelled with I4C at (2-21, was fed as an aqueous solution of its glucoside.Degradation of the derived hellebrin showed that none of the radioactivitywas located in the steroidal nucleus.An important intermediate, 2-decaprenylphenol (44; R = H), in thebiosynthesis of ubiquinone- 10 (45) has been isolated from Rhodospirillumr u b r ~ m . ~ l This is apparently the first known precursor containing bothan aromatic ring and a polyisoprenyl side-chain. Its biosynthesis probablyinvolves alkylation of p - hydroxybenzoic acid by a decaprenyl pyrophos-phate to give the acid (44; R = CO,H), which is then decarboxylated.Newresults concerning the transformation of the diterpene ( - )-lraurene intogibberellic acid (46) have been announced.42 Gibberellin A12, labelled with14C as shown (47), was added to a fermentation of Gibberella. fujikuroi. De-gradation of the derived [ 14C]gibberellic acid showed that all the radioactivity0MeIEH2*CH=C-CHd,,HHO(44)6 Gluc-Rham.0OH0Me00CH =Meresided as expected in the terminal methylene group. The [14C]-diol, ob-tained by the reduction of the acid (47) with lithium aluminium hydride,wa*s an even better precursor of gibberellic acid.Polyketides and Polyacety1enes.-A new approach to the chemical studyof poly-8-ketone cyclisations has been announced.43 The biosynthesis ofterrein (48) from acetate and malonate in Aspergillus terreus is interesting inthat the five-membered ring contains two linked '' carboxyl " carbons a t the6,7-p0sitions.~~ This is illustrated by the labelling pattern (48) produced from[l-lWIacetate. Terrein may possibly be derived from the contraction of aprecursor with a six-membered ring.The biosynthesis of auroglaucin (49)and fuscin (50) involves the condensation of a cyclised polyketide unit (thelabelling pattern from [1-14C]acetate is shown) with a C,-fragment derivedfrom 1nevalonate.45 Acetate was also incorporated into the mevalonatefragment but here, unexpectedly, the labelling (A and t in the formulae) wasnot uniform. Further progress is reported in the elucidation of tetracyclinebi0synthesis.4~ An intermediate accumulated by a blocked mutant ofStreptomyces uureofmiens has been identified as 4- hydroxy-6-methylpre-tetramid (51).Bentley and Gatenbeck 47 have shown that the entire carbon skeleton ofmollisin (52) is derived in Mollisia caesia from acetate or malonate.At least( 4 8 ) (49)I-CHMe,two polyketide chains must be involved in the biosynthesis: one possibilityis indicated (53). Orsellenic acid (54) is probably the true precursor offumigatin (55) in Aspergillus fumigatus.48 Good evidence has been obtained 49to suggest that the amino-acid orcylalanine (56), of Agrostemma githago, isderived by condensation of orsellenic acid and serine.The fern, Dryopteris marginalis, produces a family of methylene- bis-pholoroglucinol derivatives, for example, desaspidin (57).Penttila, Kapadia,and Fales 5O found that three methyl groups [asterisks in (57)] and thecentral methylene group were derived with comparable efficiency from the8-methyl group of methionine. The remainder of the molecule is constructed,presumably, from two polyketide acylphloroglucinol units. Evidence ispresented for a biosynthetic intermediate such as (58). Attention is drawnt o the recent work by Samuelson61 on the biosynthesis of prostaglandin El(59) in vesicular gland preparations. Eicosa-8,11,14,-trienoic acid was shownto be a precursor. Experiments with lSO, established that all three oxygenfunctions were derived from molecular oxygen. Of especial interest was theproof that both oxygen atoms on the five-membered ring came from the sameoxygen molecule : a plausible mechanistic explanation of this is presented.The investigation of polyacetylene biosynthesis has been especiallyfruitful this year. Bohlmann and his colleagues have studied the biologicalconversion of [ 1 -14C]dehydromatricaria ester (60) into the thioethers (61)and (62) in Anthemis t i ~ ~ t o r i ~ ~ . ~ ~ ~ 53 In each case an appropriate degradationof the end product was carried out. The production of an aromatic ringin the ether (62) is particularly interesting;53 the authors have proposed amechanism involving a 1,7-rnethyl migration. The incorporation of [2-W]-dehydromatricaria ester into the thiophen (63) in Chrysanthemum vulgarehas also been established.54 The biological formation of thiophen derivativesby the addition of H,S, or its e q ~ i v a l e n t , ~ ~ to polyacetylenes is of widespreadimportance. Feeding experiments with Echinops sphuerocephlus have ea-tablished a number of these transformation^.^^ For example, the tritium-labelled tridecenpentyne (64) was incorporated into the dithienyl (65).Shikimic Acid and Derived Aromatic Compounds.-A comprehensivereview of the chemistry and biochemistry of shikimic acid (66) has beenpublished.57 It has been shown 58 that chorismic acid (67) is an intermediatein the biological conversion of shikimic acid into prephenic acid (68). Thetransformation (67) +( 68) also proceeds nonenzymatically a t 70 O and pH 8.Full details of the chemical investigations by Edwards and Jackmannleading to the structure (67) are now available. These authors have estab-lished that a compound, isolated by Lingens and Luck,GO and assignedstructure (67) is in fact different from chorismic acid.with Rhus typhina have led to the tentative conclusion that gallic acid maybe derived, at least in part, from dehydroshikimic acid without the inter-vention of a cinnamic derivative.Biosynthetic experiments with labelled phenylalanine or coniferin haveproved useful in elucidating the structure of ligniaG2 For example, degrada-tion of spruce ligiiin derived from [ 2-14C]phenylalanine (69) gave radioactiveveratric acid. This suggests that radical coupling must occur to some extentin the sense shown [(70) and (71)], one of the coniferyl side-chains being losta t a later stage.The predicted 63 re1at)ionship between rotenone (72) and the isoflavonoidshas received experimental support. Crombie and Thomas 64 have observedthe incorporation of [%1*C]phenylalanine (69) into rotenone in Derriselliptica. Degradation showed that the radioactivity was confined to posi-tion 12a. Clearly an aryl migration, 6a--+12a, analogous t o that known 65to occur in isoflavanone biosynthesis, had taken place a t some stage in thebiosynt hetic sequence.Compounds," ed. W. D. Ollis, London, Pergamon Press, 1961, p. 59.6 5 H. Grisebach, " Recent Dcveloprnents in the Chemistry of Natural Phenoli

ISSN:0365-6217    

DOI:10.1039/AR9656200211

出版商:RSC    

年代:1965

数据来源: RSC

摘要:

1. INTRODUCTIONBy D. J. Manners(The Heriot- Wutt University, Edinburgh, 1 )DURING the past decade, investigations of enzymes have developed fromdescriptive studies of isolation, purification, and properties to the examinationof the detailed stereochemical specificity and mechanism of action. Sub-stantial progress has followed from the application of physicochemicaltechniques and, in particular, of isotopic labelling. The present Reportincludes an authoritative account of such studies with special emphasis onwork published since 1961. From the many examples quoted, those describ-ing the stereochemical changes involved in the conversion of mevalonateinto squalene, lanosterol, and cholesterol are particularly important. In thiswork, the stereospecific synthesis of mevalonate labelled with deuterium ortritium at each of the two 4-positions was a significant preliminary.The microbiological oxidation of aromatic compounds was last consideredin 1956, and it is appropriate to report on the substantial progress which hasbeen made in this field since then. Alternative routes of metabolism to thosealready established have been discovered and considerable progress made instudies on both the purification and mechanism of action of osygenases, inwhich oxygen atoms from molecular oxygen are directly incorporated intothe substrate.The regulation of the synthesis of enzymes concerned iii themetabolism of trytophan and mandelate are also considered.It is customary for the Biological Chemistry section to include at leastone survey of the major classes of naturally occurring high polymers. Sincenucleic acids are being described elsewhere (p.402) and neutral polysac-charides have been reviewed in 1964 and 1965, attention is now focused oncarbohydrate sulphates, and on proteins. Although certain aspects of thechemistry of polysaccharide sulphates have been included in previousReports, recent progress in this field has been so substantial (see for example,Tables 1 and 2, pp. 472, 481) that a more complete account is required.The final section describes the continued and significant progress whichhas been made in studies on peptides and proteins2. THE STEREOSPECIFICITY OF ENZYMIC REACTIONSBy J. W. Cornforth and G. Ryback(Milstead Laboratory of Chemical Enzymology,“Shell ” Research Ltd., Sittingbourne, Kent.)Introduction.-The stereospecificity observed in the great majority ofenzymic reactions can plausibly be attributed to two main causes: the needto accept a limited range of molecular species as substrates for conversioninto a correspondingly limited range of products; and the need for specificgeometrical relationships between the functional groups taking part in thereaction, if the activation energy is to be minimized.A subtle manifestation of stereospecificity in enzymes is the capacity todiscriminate between formally identical groups in a molecule. Characteris-tlically, an enzyme modifying an a group in a substrate Caabd will select thegroup having one particular orientation with respect to b and d.This canbe demonstrated when the product of the enzymic reaction is asymmetric[as when glycerokinase converts glycerol exclusively into (A)-a-glycero-phosphate1] or when asymmetry in substrate or product is deliberatelyinduced by isotopic labelling of one of the a groups. The second is by farthe more general possibility and isotopic labels have been increasingly usedin biochemistry to explore the stereochemistry of enzymic reactions.The subject was excellently reviewed up to 1961 by Levy, Talalay, andVennesland;2 the present Report is largely devoted to progress since thatdate.* With few exceptions, this Report deals with asymmetry revealedby isotopic labelling, since the stereochemical relation between a substrateand a product which are asymmetric when unlabelled is self-evident whenthe absolute configurations are known. In addition, some representativework on exploration of the stereochemical environment of the active sites ofenzymes is mentioned.For most substrates of type Caabd, a is hydrogen, and modern physicalmethods have greatly facilitated recognition of asymmetric treatment of amethylene group by an enzyme. First, polarimeters may now have sensi-tivities of 10-4 to degrees of rotation from the visible region to near thelimit of the quartz ultraviolet.Optical activity due to stereospecific re-placement of one hydrogen atom in a methylene group by deuterium canthus be detected in samples of a few milligrams. Secondly, enzymic reac-tions leading to the loss of one hydrogen atom from a methylene grouplabelled stereospecifically with a hydrogen isotope can be followed by massspectrometry when deuterium is the isotope, or by measuring a shift inT : 14C ratio from that of a doubly-labelled substrate when the asymmetry ofC.Bublitz and E. P. Kennedy, J . Biol. Chem., 1954, 211, 963.H. R. Levy, P. Talalay, and B. Vennesland, Progr. Stereochem., 1962, 3, 299.* The practice, used in that Review,2 of designating acidic substrates of enzymicexperiments as their anions, e.g., “ succinate,” in the text, but as their acidic forms inpictorial formulae, is continued hereCORNFORTH AND RYBACK : STEREOSPECIFICITY O F REACTIONS 429the methylene group is due to tritium. Conversely, stereospecific non-enzymic elimination reactions may be used to demonstrate enzyme-inducedasymmetry in a labelled methylene group, provided that an adjacent asym-metric centre can direct the course of elimination. Thirdly, the alterationproduced in the n.m.r.spectrum of a substance, when one or more of itshydrogen atoms is replaced by deuterium, can be used to relate the absoluteconfiguration of an asymmetrically deuteriated methylene group with thatof an adjacent centre of known absolute configuration. Fourthly, and sofar uniquely, a specimen of monodeuterioglycolate, produced by the actionof muscle lactic dehydrogenase on deuterioglyoxylate (1 ), has been shown 3by X-ray and neutron-diffraction measurements with the 6Li salt to haveE n z ., NADHIl___fI(I) L C02H - ~ n z ., NAD+t,he (&')-configuration (2). The anomalousD x"HO C02Hneutron-scathering(2)amplitude of6Li and the differing neutron-scattering amplitudes of H and D gave Bijvoetinequalities from which the absolute configuration was deduced.Propionyl-coenzyme A Carboxylase, Methylmalonyl-coenzyme A Epi-merase, Succinyl-coenzyme A Mutase.-This enzymic sequence mediatesinterconversion of propionate and succinate in mammalian tissue and in someba~teria.~ Propionyl-coenzyme A (or CoA) carboxylase, which has beenobtained crystalline from pig heart, converts propionyl-CoA, in the presenceof biotin, ATP, and bicarbonate, into methylmalonyl-CoA. Methylmalonyl-CoA is rearranged by a vitamin B ,,-coenzyme-dependent isomerase, methyl-malonyl-CoA mutase, to succinyl-CoA.The carboxylase is stereospecificand the methylmalonyl-CoA which it produces is the enantiomer (or strictlyspeaking the epimer, since coenzyme A is itself asymmetric) of the formutilized by the mutase. A third enzyme, methylmalonyl-CoA epimerase,must therefore intervene to interconvert the two molecular species, spon-taneous interconversion being quite slow. The stereochemistry of all stageshas now been investigated and the conclusions are summarized as shownThe stereochemistry of the carboxylase product was demonstratedindependently by two groups of workers. Both proofs depended on reduc-tion of the product (4) by Raney nickel to a partially racemized but stilloptically active 3-hydroxy-2-methylpropionic acid (7 ; R = H).converted this into the dextrorotatory phenylurethane (7 ; R = COeNHPh),which was synthesized from (2S,3S)-2-amino-3-methylsuccinic acid (8) ofknown absolute configuration.The other group used enzymic carboxyla-tion of 2,2-dideuteriopropionyl-CoA with KH14C03 to obtain a 14C-labelledproduct (4: H* = D). Racemization on reduction of this deuteriated(3-6).One groupC. K. Johnson, E. J. Gabe, M. R. TayIor, and I. A. Rose, J. Amer. Cheni. SOC.,Y. Kaziro and X. Ochoa, Adv. Enzymol., 1964, 26, 283 (Review).M. Sprecher, M. J. Clark, and D. €3. Sprinson, Biochem. Biophgs. Res. Comm.,J. RBtey and F. Lynen, Biochern. Z., 1965, 342, 256.1965, 87, 1802.1961, 15, 581430 B I 0 LO G I C AL C H E MI S TRYH MeH Me Degradn. H O 2 C P > i l H( 6 stages) H NH,product with nickel was slight ; the 3-hydroxy-2-methylpropionic acid wasconverted into the hydrazide (9; H* = D), portions of which were mixedwith larger amounts of synthetic (B)-, (@, and (RS)-hydrazide, preparedfrom the resolved optical isomers of 3-hydroxy-2-methylpropionic acid.The radioactivity due to the enzymically prepared materia,l remained withthe (R)- and (RS)-hydrazide on recrystallization, but was largely lost fromthe (8)-hydrazide; the material of enzymic origin was therefore the (R)-hydrazide (9).The absolute configurations of the synthetic material hadbeen assigned by st correlation through the oxazolidone (10) with (8)-alanine(ll), from which the enantiomorph of (10) was prepared by reduction to(8)-alaninol and ring-closure with phosgene.Both investigations led to thesame conclusion: that the product of enzymic carboxylation is (&)-methyl-malonyl-CoA (4). The method of deducing stereochemistry from the separa-bility or inseparability of radioactivity from synthetic enantiomorphs isadvantageous since the enzymic experiments can be on the usual scale of afew micromoles.Me H k' HZN COlHLiAIHT - HMe 'OH(13)Rktey and Lynen6 also determined the absolute configuration of thehydrogen displaced on carboxylation. (2R,3R)-2,3-Epoxybutane (12) wasreduced by lithium aluminium tritide to a butanol(l3; H* = T) oxidized byhypobromite to (5)-2-tritiopropionic acid, the coenzyme A derivative ofwhich (3; H* = T) was used for carboxylation on the enzyme.The productafter conversion (with suitable dilution) into the oxazolidone (9; H* = T)retained 80% of the tritium originally present. It follows that, in theenzymic carboxylation, the carboxyl group in the product occupies thCORNFORTH AND RYBACK : STEREOSPECIFICITY O F REACTIONS 431spatial position of the displaced hydrogen, provided that the retention oftritium is not an isotope effect operating on a non-stereospecific process.This latter possibility was dismissed by examining (R)-2-tritiopropionyl-CoA,which lost all its tritium on carboxylation.7The absolute configuration (5) of the methylmalonyl-CoA utilized by themutase follows from that of (4). The mechanism of action of the epimerasehas been established4 as an exchange of the tertiary hydrogen with protonsfrom the medium (and not, for example, a shift of the SCoA group or adecarboxylation-carboxylation) ; thus, a plausible intermediate is the planarenolate-ion (14).It is still unknown whether the initial rate of racemizationis equal to the initial rate of hydrogen exchange : in other words, whether theintermediate (14) can add a proton from the medium indifferently on eitherside, or whether its choice is limited, by attachment to the enzyme, to accept-ing a new proton with inversion of configuration and exchange, or re-attach-ing the original proton with retention and no exchange. Since the hydrogenexchange can be measured in deuterium oxide by n.m.r.,8 and the rotationalchange should be measurable in the same medium by a modern polarimeter,the experiment appears possible.The mutase which interconverts (R)-methylmalonyl-CoA and succinyl-CoA has been shown to induce an intramolecular 1 : 2-shift of the CO*S*CoAgroup accompanied by a 1 : 2-shift of hydrogen in the opposite direction.*When (R)-methylmalonyl-CoA is available and epimerase is absent, theMeHOZC \v A SCoA0- (14)succinyl-CoA contains no stably bound hydrogen from the medium; but ifpropionyl-CoA is converted into succinyl-CoA by the sequence of three en-zymes in deuterium oxide, the (22)-methylmalonyl-CoA contains deuterium( 5 ; Ht = D) and this persists in the succinyl-CoA.This experiment hasbeen done,5 the enzyme preparation consisting of an acetone powder frombeef liver mitochondria; the succinic acid derived from hydrolysis of thethiolester was dextrorotatory and hence had the (8)-configuration(6; HT = D), since (R)-rnonodeuteriosuccinic acid is laevor~tatory.~ Dis-crepancies between the optical rotatory power and the deuterium content ofthe succinic acid suggested that other enzymes had also been at work.Succinic Dehydr0genase.-Conversion of succinate to fumarate by pre-parations of this enzyme in the presence of electron acceptors is a trans-elimination of hydrogemlo However, anmobic incubation of succinatewith the enzyme in the presence (necessary for a useful rate of reaction) offumarate leads to exchange of succinate hydrogen with the aqueous medium.D.Arigoni, F. Lynen, and J. RBtey, Helv. Chim. Acta, 1966, 49, 311.P.Overath, G. M. Kellerman, F. Lynen, H. P. Fritz, and H. J. Keller, Biochem. Z.,J . W. Cornforth, G. Ryback, G. Popjak, C. D o d g e r , and G. Schroepfer,1962, 335, 500.Bwchern. Biophys. Res. Comm., 1962, 9, 371.lo T. T. Tchen and H. van Milligan, J . Amer. Chem. SOC., 1960, 82, 4115432 BIOLOGICAL CHEMISTRYWith the artificial substrate (8)-chlorosuccinate (15), Gawron et uZ.11 foundthat, in a deuterium oxide medium, one hydrogen of the substrate wasexchanged preferentially ; with succinate, two hydrogens could be exchangedon prolonged incubation. The succinate isolated after shorter incubationtimes was, however, largely monodeuteriated,12 and this species was shownby its optical rotatory dispersion to be (S)-monodeuteriosuccinate.Thisenantiomorph was also shown to be formed by hydrodechlorination of thedeuteriated (8)-chlorosuccinate, which must therefore have been (28)-chloro-(3R)-[3-D]succinate (15 ; H* = D). trans-Elimination of hydrogenfrom succinate to give fumarate necessarily removes one (R) and one ( S )hydrogen: it appears that the (8) hydrogen is the first to be labilized. (Wefollow here a suggestion of Prof. V. Prelog that an a substituent in a moleculeCaabd may be designated as (22) [or (S)] if promotion of this group to ahigher rank than the other a group confers (R) [or ( S ) ] asymmetry on theC atom.) The use of negative-ion mass spectrometry in the measurementsof deuteriosuccinic acid is noteworthy.Aspartwe Analogues.-The known trans-geometry of the addition ofammonia to fumarate a,nd ifs elimination from aspartate on the enzymeaspartase was utilized to study the stereospecificities of argininosuccinase 13and of adenylosu~cinase.~~ Both these fumarate-yielding eliminations arealso trans.From analysis of the proton coupling constants observed withthe N-acetyl anhydrides of the diastereoisomeric 3-methylaspartates, andcomparison of these with similar measurements on the O-acetyl anhydride of(2S,3R)-[3-D] malate it was concluded l5 that the methylaspartate active inthe methylaspartate ammonia-lyase reaction has the (28,3X) configurationand hence that the addition and elimination catalysed by this enzyme aretrans.This assignment supports an experiment on the stereochemistry of theglutamate mutase reaction, a process requiring vitamin B,, coenzyme ; for(ZX,3S)-3-methylaspartate is also a substrate for this enzyme. Sprecherand Sprinson 16 incubated mesaconate in deuterium oxide with a cell-freeextract of Clostridium tehnomorphum and isolated a, 4-deuterioglutamic acid(17) (18)(17).Chemical oxidation of this gave (R)-monodeuteriosuccinic acid (18).Since the glutamate (17) presumably was formed on the mutase from(ZS,3X)-[3-D]3-methylaspartate (16), the conclusion was that inversion ofl1 0. Gawron, A. J. Glaid, J. Francisco, and T. P. Fondy, Nature, 1963, 197, 1270.l2 0. Gawron, A. J. Glaid, and J. Francisco, Biochem. Biophys. Res. Comm., 1964,l3 H . D. Hoberman, E. A. Havir, 0. Rochovansky, and S. Ratner, J. Biol. Chena.,l4 R.W. Miller and J. M. Buchanan, J. Biol. Chem., 1962, 237, 491.l5 H. J. Bright, R. E. Lundin, and L. L. Ingraham, Biochemistry, 1964, 3, 1224.l6 3%. Sprecher and D. B. Sprinson, Ann. New York Acad. Sci., 1964, 112, 655.16, 156.1964, 239, 3818CORNFORTH AND RYBACK : STEREOSPECIFICITY O F REACTIONS 433configuration occurs a t the carbon atom on which a glycine residue is re-placed by hydrogen.Citrate Condensing Enzyme, Aconitase, 5-Dehydroquinate Dehydratase.-Hanson and Rose17 incubated 5-dehydroshikimate (19) and NADH in tri-tiated water with an extract of Aerobacter uerogenes, obtaining a 6-mono-tritiated quinic acid (20). From the known absolute configuration of quinicacid, the tritiated citric acid (21) obtained from this specimen by oxidationbad the (322) configuration shown.The tritium atom in (21) proved to bethat removed as water by the enzyme aconitase. This confirmed the earlierassignments,2 based on Hudson's lactone rule, that the (A)-methoxycarbonylgroup of citrate is that derived from oxaloacetate, and that the eliminationsand additions of water catalysed by aconitase are trans. Further, theaddition of water to 5-dehydroshikimate is, uniquely, cis. This was ex-plained by supposing that addition of hydroxyl ion to the ap-unsaturatedketonic system occurs as a first stage, followed by protonation of the resultingenol.Isocitric Dehydrogenase.-This universal enzyme mediates the conversionof (2&38)-isocitrate (22) into 2-oxoglutarate (23) and carbon dioxide.Nicotinamide-adenine dinucleotide phosphate (NADPS) is the coenzyme,and a proton from the medium appears in the product.The stereochemistryof this change was demonstrated independently by two groups. Englardand Listowsky ran the enzymic reaction in deuterium oxide, and oxidizedthe product (23; H* = D, Hi = H) to (8)-monodeuteriosuccinic acid(24; H* = D, Ht = H). Lienhard and Rose 19 established that Z-oxoglu-tarate in contact with the enzyme and the reduced form of the nucleotideE n ~.,H:o_I)_.f--Enz.Ht HaT HH 02CHO Hl7 K. R. Hanson and I. A. Rose, Proc. Nut. Acad. Sci. U.S.A., 1963, 50, 981.l8 S. Englard and I. Listowsky, Bwchem. Biophys. Res. C O ~ ~ L ~ . , 1963, 12, 356.Is G. E. Lienhard and I. A. Rose, Biochemi8try, 1964, 3, 185434 BIOLOGICAL CHEMISTRYexchanged with the medium only the hydrogen which is introduced ondecarboxylation of isocitrate.This enzymic exchange carried out with2-oxoglutarate randomly labelled with tritium in the 3-position theIefore gavezb 2-oxoglutarate (23; H* = H; Ht = T) labelled at the non-exchangeablehydrogen. This 2-oxoglutarate with glutamic dehydrogenase gave glu-tamate (25) converted by chemical degradion into (8)-aspartate (26) and(&)-malate (27). The tritium in these specimens was almost entirely retainedon treatment with aspartase and fumarase; since these enzymic reactions areknown to be trans-addition-eliminations, the stereochemistry of the tritiummust have been as shown. It is interesting that here, as with propionyl-CoAcarboxylase, the introduced hydrogen occupies the steric position of thedisplaced carboxyl.Isocitrate Lywe.-This enzyme reversibly changes (2R,3X)-isocitrate(28) into succinate and glyoxylate.In a detsrium oxide medium, unlabelledisocitrate and a partially purified enzyme from yeast gave succinic acidcontaining 1.4 atoms of deuterium per molecule.20 The optical rotatoryH COlHEnz., D 2 0+ , COlHC02H - H OZC *C H 2 E n z . HOIC.CH2 C02H CH 0H "OHdispersion of this specimen showed dextrorotrttions m. 1.4 times the corre-sponding lzvorotations of (R)-monodeuteriosuccinic acid. The presump-tion was that some initially formed (8)-deuteriosuccinate, (29) because of thereversibility of the reaction and the symmetry of the succinate ion, wentthrough another cycle to emerge as (88)dideuteriosuccinate.It is interest-ing that here the introduced hydrogen atom does not occupy the spatialposition of the displaced group but produces an apparent inversion ofconfiguration. This conclusion is supported by other experiments 20@ withtritiated substrates.Enzymes of Squalene Biosynthesk-The enzymes converting six mole-cules of mevalonate (31) into one molecule of squalene (35) have been iden-tified and several have been extensively purified; the usual sources are mam-malian liver and yeast. The course of the biosynthesis (Scheme 1) was dis-cussed by Bloch 21 in a 1964 Nobel lecture, and Clayton 22 has recently reviewedthe subject. The three methylene groups of mevalonate all change theirbonding during biosynthesis ; the stereochemical consequences of labellingthese groups asymmetrically with hydrogen isotopes have been ~tudied.~3Stereospecific chemical synthesis (Scheme 2) was used to prepare meva-2o M.Sprecher, R. Berger, and D. B. Sprinson, J . BioE. Chem., 1964, 239, 4268.zoaK. R. Hanson, Fed. Proc., 1965, 24, 229.2 1 K. Bloch, Science, 1965, 150, 19.22 R. B. Clayton, Quart. Rev., 1965, 19, 168, 201.23 G. Popjik, Biochem. J . , 1965, 96, 1P; J. W. Cornforth, ibid., p. 3P; J. W. Corn-forth, R. H. Cornforth, C. Donninger, G. Popjbk, C. Ryback, and G. J . Schroepfer,Proc. Roy. SOC., 1966, B , 163, 436; C. Donninger and G. Popjhk, ibid., p. 465; J. W.Cornforth, R. H. Cornforth, C. Donninger, and G. Popj&, ibid., p. 492CORNBORTH AND RYBACK : STEREOSPECIFICITY OF REACTIONS 435M e ?H Enz.Me OH H * HH02C - H02C & CH 0OH (30) S C O K H I / H*"Ht (31)RH' H H+ HEnz. ~OPPH"OPPHf"Hf(32) (3 3 ) dOPP + /J + ,* H* tiOPP OPPH+ H" 'H4 H* H*(33) (32) (32)v f "'*634)OPP(35)SCHEME 1.R = ADP-ribose; R' = ADP-ribose phosphate.lonate labelled with deuterium or tritium a t each of the two 4-hydrogenatoms. The lactone (36) and the trans-hydroxy-acid (41) were convertedinto the geometrically isomeric benzhydrylamides (37) and (42), each ofwhich was epoxidized by perbenzoic acid. The epoxides (38) and (43) werereduced by lithium borodeuteride or lithium borotritide to mevalonylbenzhydrylamides (39 and 44; Htt = D or T). The mevalonic acids (40and 45; Htt = D or T) obtained by hydrolysing these amides were accom-panied by their enantiomorphs, but since (3X)-mevalonate is not utilized fo436(36)BIOLOGICAL CHEMISTRYCHzOH( 3 7)(4 4)SCHEME 2.R = GO*NH.CHPh2; Reagents: 1, (C,HllN),C; 2, Ph,CHATH2;3, PhC0,H; 4, LiBH,tt; 5, NaOH.polyisoprenoid biosynthesis the enzymically active forms had the absoluteconfigurations shown.Each molecule of mevalonate participating in squalene biosynthesis losesa hydrogen atom from C-4, either when isopentenyl pyrophosphate (32) isisomerized to dimethylallyl pyrophosphate (33) or when coupling of C, unitsoccurs.The two deuterio-mevalonates (40 and 45; Htt = D) were usedseparately as substrates for the synthesis of farnesyl pyrophosphate (34) by apartially purified enzyme preparation from rat liver.The mass spectrum offarnesol obtained from this product by the action of alkaline phosphataseshowed the presence of three atoms of deuterium when (4R)-[4-D]rnevalonate(45; Hft = D) was the precursor, and of none when (48)-[4-D]mevalonate(40 ; Htt = D) was used. Similarly, squalene from (4R)-[4-T,2-14C]mevalo-nate (45; Htf = T) had the same 14C: T ratio as the mevalonate, whereassqualene from the (48)-mevalonate (40 ; Hit = T) was tritium-free.Asymmetric labelling of one hydrogen atom on C-5 of mevalonate waseffected by reduction of mevaldate (30) with stereospecifically (4R) tritiatedNADH in the presence of mevaldic reductase, for when the product mevalo-nate was converted enzymically via farnesyl pyrophosphate into farnesol,enzymic oxidation of this alcohol to farnesal by NADf and liver alcoholdehydrogenase caused loss of all tritium from C-1.This carbon (and there-fore C-5 of the parent mevalonate) thus had the (R)-configuration providedthat oxidation of farnesol on liver alcohol dehydrogenase follows the samestereocheinical course as that established for ethanol.24 The latter assump-24 R, U. Lemieux and J. Howard, Canad. J . Chenz., 1963, 41, 308CORNFORTH AND RYBACK : STEREOSPECIFICITY O F REACTIONS 437tion was supported25 by oxidation on the same enzyme of geraniol stereo-selectively labelled with tritium a t C-1 by Streitwieser's 26 chemical pro-cedure.Asymmetrically deuteriated mevalonate (31; Ht = D) was now pre-pared from mevaldate and (4R)-[4-D]NADH on mevaldic reductase and wasconverted into squalene (35; Ht = D).Lawulinic acid from ozonolysis(Scheme 3) of this squalene on oxidation by hypoiodite gave (R)-mono-Y v v4'''(46) (46)SCHEME 3.Reagents: I, 0,; 2, HC0,H; 3, NaOl.deuteriosuccinic acid (46; Hb = D). It followed that each association of C,units in squalene biosynthesis is accompanied by inversion at tjhe carbonatom from which the pyrophosphate ion is eliminated.Association of two molecules of farnesyl pyrophosphate (34) to onemolecule of squalene is accompanied by displacement of a hydrogen atomfrom one of the carbon atoms forming the new C-C bond and intiroduction inits place of a (48)-hydrogen 27 from NADPH. The steric position occupiedby the introduced hydrogen was determined 28 by using, as the precursor inan enzymic synthesis of squalene, mevalonate fully deuteriated at C-5.Ozonolysis of this squalene gave, from the four central carbon atoms (as),the optically active (8)-trideuteriosuccinic acid (49).The stereochemistryof the introduced hydrogen is therefore that shown in (35) as HS. Thisassignment was confirmed 29 independently by biosynthetic conversion ofsqualene, itself biosynthesized from synthetic [14Clfarnesyl pyrophosphateand (M)-[4-T]NADPH, into cholic acid via cholesterol. The T : 14C ratio25 C. Donninger and G. Ryback, Biochem. J., 1964, 91, 1lP.28 A. Streitwieser, J. R. Wolfe, and W. D. Schaeffer, Tetrahedron, 1959, 6, 338.27 G. Popjhk, G. Schroepfer, and J.W. Cornforth, Biochem. Biophys. Res. Comni.,28 J. W. Cornforth, R. H. Cornforth, C. Donninger, G. PopjQk, G. Ryback, and29 B. Semuelsson and De 1%'. S. Goodman, J . Biol. Cheni., 1963, 239, 98.1961-1962, 6, 438.G. F. Schroepfer, Biochem. Biophys. Res. Comm., 1963, 11, 129438 BIOLOGICAL CHEMISTRYD HD (49)in the cholic acid (50) was halved on conversion into methyl 3%,7cr-diacetoxy-12-oxo-5~-cholanoate (51) and reduced alinost to zero by subsequent enoliza-tion to exchange the C-11 hydrogens. This is the result expected fromcyclization of squalene tritiated as in (35; HO = T) since [lZg-T]- and[ lla-TI-cholesterols would be formed in equal amounts and the 12B-tritium,which should be undisturbed by the biosynthetic 12a-hydroxylation, wouldbe eliminated on oxidation to (51).Both (5R)-[5-D]- and (SR)-[5-T]-mevalonates (31; Kt = D or T) werefound to be converted into squalene without loss of hydrogen isotopes;23hence, the hydrogen eliminated during the enzymic conversion of farnesylpyrophosphate into squalene originated as a (58) hydrogen of mevalonate.Thus, squalene biosynthesized from (5$)-[ 5-Dlmevalonate must have, a tthe central carbon at which exchange of hydrogen has occurred, the ccn-figuration (35) where Ht= D and He = H, the other central carbon carryingone deuterium atom.When this squalene is degraded by ozonolysis, thesecentral carbons appear as the methylene groups of a 2,3-dideuteriosuccinicacid, which is either (88) (if configuration is retained at the carbon whichdoes not exchange hydrogen) or (XR) (if configuration is inverted).In theevent, the succinic acid was the optically inactive meso (SR) form (47 ; Ht = D,HO = H); thus, inversion of configuration occurs here as with the coupling ofThe availability of (4R) -[4-T ; 2-14C] and (45) -[4-T ;2-14C]meva~lonates ofhigh specific activity opened new lines of investigation in polyisoprenoidbiosynthesis. Thus, it was found 30 that rubber biosynthesized from thesemevalonates by Hevea brasiliensis latex incorporated all of the tritium fromthe (48)-mevalonate and none of the tritium from the (4R)-mevalonate.This is the exact opposite of what happens in squalene biosynthesis. Thedifference is presumably due to the &-geometry of the double bonds inrubber : trans, trans-farnesyl pyrophosphate simultaneously formed by thelatex preparations showed the ‘‘ squalene ”, not the “ rubber ,” pattern ofretention and elimination of tritium.The biosynthesis of phytoene and 8-carotene from mevalonate in carrotslices follows the ‘‘ squalene ” ~ a t t e r n , ~ l the (4S)-hydrogen being eliminated.30 B.L. Archer and D. Barnard, Biochem. J., 1965,96,1P; B. L. Archer, D. Barnard,E. G. Cockbain, J. W. Cornforth, R. H. Cornforth, and G. PopjBk, Proc. Roy. SOC.,1966, By 163, 619.3l T. W. Goodwin and R. J. H. Williams, Biochem. J., 1965, 94, 5C.c5 unitsCORNFOETH AND RYBACK : STEREOSPECIFICITY O F REACTIONS 439From the eight molecules of mevalonate incorporated in each molecule ofthe carotenoids, no (4R)-hydrogen is lost when phytoene is formed, but twoof the eight (4R)-hydrogens are absent from #?-carotene, as shown by changesin the T : 14C ratio.Presumably these two are lost when the cyclohexanerings are closed (e.g., 52-453).UST q k '/ ,... rnzr = T q ....(5 2) (5 3)The established intermediate stages 23 in the biosynthesis of cholesterolfrom six molecules of (4R)-[4-T ;2-14C]mevalonate require that, of the six(4R)-hydrogen atoms, five shall persist in lanosterol (54) and only three incholesterol (55) (assuming that elimination and not rearrangement occursfrom C-3 and C-5 of the steroid nucleus). Of the six labelled carbons,all survive in lanosterol and five in cholesterol. Thus, if the T : 14C ratiois 1 : 1 in mevalonate, it should be 5 : 6 in lanosterol and 3 : 5 in choles-terol.This was verified for lanosterol and cholesterol synthesized from(4R)-[4-T ;2-14C]mevalonate by microsomal and soluble enzymes from ratliver.32 Of the three surviving tritium atoms, one was located at C-17 andthe other two in the side-chain (presumably a t C-20 and C-24), in agreementwith theory. The 3 : 5 ratio found for cholesterol was also found for fuco-sterol (56) synthesized by Fucus spiralis from the same mevalonate pre-cursor.33 This implies that the tritium atom which occupied (3-24 has notbeen eliminated but rearranged, wost probably to C-25 as forecast earlier,3*on alkylation of the side-chain.Stearate Dehydrogenation.-The efficient conversion of stearic acid (57)into oleic acid (58) by growing cultures of a strain of Corynebacterium diph-theriae has been shown 35 to involve stereospecific loss of two hydrogen atoms(H* and Ht in formula 57).The product is not seriously contaminated byendogenous stearic or oleic acid or by products of further metabolism.(S)-9-Tritiostearic acid (60) was synthesized from (R)-9-hydroxystearic acids2 J. W. Cornforth, R. H. Cornforth, C. Donninger, G. PopjQk, Y. Shimizu, S. Ichii,E. Forchielli, and E. Caspi, J . Amer. Chem. SOC., 1965, 87, 3224.33 L. J. Goad and T. W. Goodwin, Biochem. J . , 1965, 96, 79P.34M. Castle, a. Blondin, and W. R. Nes, J . Amer. Chem. Soc., 1963, 85, 3306.35 G. F. Schroepfer and K. Bloch, J. Biol. Chem., 1965, 240, 54440 BIOLOGICAL CHEMISTRYby reducing the derivative (61) with lithium aluminium tritide (inversion ofconfiguration a t C-9) and oxidizing the resulting primary alcohol.Theenantiomer of (60) was similarly obtained from (S)-9-hydroxystearic acid .j.;l-.H f H(57)T HRH D H H D - E n z . K%H D-N:N-D - R%R, + R%~'(C. d r p h t h e r i a e ) *R' H b D \ H( i ) LiAITrHO HR L R 'HO HR = *[CH,I7*CO,H; R' = .[CHJ7*CH,.(62) derived from (61) by a Walden inversion. Loss of tritium from the(R)-enantiomer of (60), but not from (60) itself, during conversion into oleicacid established the stereochemistry of the reactioii a t C-9. Similar experi-ments based on natural (R)-10-hydroxystearic acid (63;H* = H) led to thesame conclusions regarding C-10 but, since the absolute configuration of (63)was inferred from its having the same sign of rotation as (R)-9-hydroxy-stearic acid, the results were confirmed by incubating the racemic mixture(59), prepared from oleic acid by cis-addition of deuterium, with C.diphtheriaeand comparing the proportions of di- , mono-, and non-deuteriated moleculeswith the ratios expected from the two stereochemical possibilities a t C-10.A considerable isotope effect was observed for the elimination of hydrogenfrom C-9, but not for that from (3-10, suggesting that the removal of the twohydrogen atoms is not synchronous. It is pointed out that, since the mech-anism of the reaction is not known, interpretation of the results as an enzymic&-dehydrogenation need not follow.The stereochemistry of the dehydrogenation performed by C.diphtheriaehas been used 36 to show that, when oleic acid is hydrated by a fermentingculture of a Pseudomonm species to give (R)-10-hydroxystearic acid (63), ahydrogen atom from the medium is introduced at C-9 in a configuration(H* in formula 63) consistent with a trans-addition of water t o oleic acid.Propanedio1dehydrase.-The stereospecificity of the reactions alreadydiscussed is so complete that an enzyme utilizing two enantiomeric substrateswith equal ease and differing stereospecificities comes as something of ashock. Dioldehydrase from Aerobacter aerogenes has been extensivelypurified37 and the most active preparations gave a single active band onstarch-gel electrophoresis. (a)- and (8)-Propanediols are both readily con-verted by this enzyme into propionaldehyde; no hydrogen from the medium36 G.F. Schroepfer, J. Amer. Chm. Soc., 1965, 87, 1411.3 7 H. A. Lee and R. H. Abeles, J . Biol. Chem., 1963, 238, 2367CORNFORTH AXD RYBACK: STEREOSPECIFICITY OF REACTIONS 441is incorporated during the dehydration which must therefore proceed bymigration of hydrogen (or conceivably of a methyl group). Vitamin B,,coenzyme is a necessary co-factor.Frey, Karabatsos, and Abeles 38 reduced (8)- and (8)-lactaldehydes (64)and (68) with liver alcohol dehydrogenase and deuteriated NADH. Theexpected stereospecificity of deuterium introduction was checked by con-verting the product propanediols into their 4-nitrobenzylidene acetals (67)and (71), which gave n.m.r.spectra different from each other and from thatof a third specimen, the acetal of propanediol prepared by non-enzymic(LiAlD,) reduction of (38)-lacta,ldehyde. It follows that both enzymicHO Ye CHOMe H A HO CHOR = ADP-ribose.reductions were stereospecific (otherwise all three spectra would have beenidentical) and that the stereospecificity of insertion of deuterium was thesame for both substrates (otherwise the first two acetals would have beenenantiomorphs with identical spectra). If the known stereospecificity ofliver alcohol dehydrogenase for acetaldehyde applies also to lsctaldehydes,the products from (R)- and (8)-lactaldehyde were respectively (65) and (69).Each propanediol was converted on the dehydrase into propionaldehyde.Examination of the n.m.r.spectra of the 2,4-dinitrophenylhydrazonesshowed that the (R)-propanediol gave 2-deuteriopropanal (66) and the(8)-propanediol gave 1 -deuteriopropanal (70). A large kinetic isotope effectwas noted only with the (R)-propanediol, with which apparent migrationof deuterium occurs.(8)-[ 2-DILacticmid (72), prepared from pyruvic acid and deuteriated NADH on lacticThis work has lately been confirmed and extended.3958 P. A. Frey, G. L. Karabatsos, and R. H. Abeles, Biochm. Biophgs. Res. Comm.,1965, 18, 551.(The legend for curve B in Figure 1 of this Paper refers to curve C andcice versa.)30 J. R&y, A. Umani-Ronchi, and D. Arigoni, Experientia, 1966, 22, 72.442 BIOLOGICAL CHEMISTRYdehydrogena.se, was reduced to (S)-[Z-D]propane-l,2-diol (73).A 1,l-dideuteriated (R)-propanediol (74) was also prepared by reduction of (R)-H D kMe M e D x Me (i) M e t h y l a t e A ( i i ) L i A I i - i i = HO CH2OH HO CDlOH M e C02H HO CO2H(72) (73) (74) (75)lactic acid with lithium aluminium deuteride. Enzymic dehydration ofboth these specimens and oxidation of the resulting propionaldehydes gavein each case the dextrorotatory (28)-[%D]propionic acid (75) identified bycomparison of its optical rotatory dispersion with that of an authenticspecimen.6These results exclude methyl migration and show that the hydrogenmigration occurs with inversion of configuration a t C-2. It was pointedout 389 39 that the attachment of both (R)- and (S)-propane-l,Z-diol to theenzyme can have the same stereospecificity with respect to the methylgroup, the 2-hydroxyl group, and the hydrogen atom of the l-hydroxylgroup.When the (R)- (76) and S-diols (77) are arranged thus, the orientation..HCof the migrating hydrogen (H*) can in each case be anti to that of the depart-ing hydroxyl, as the inversion of configuration should require. Stereo-specificity of binding to the enzyme a,nd a favoured steric relation of thereacting groups are thus preserved (but differently) in each case. This expla-nation assumes (with experimental support 37) that only one enzyme isconcerned.Stereochemical Exploration of Active Sites.-The specificity of an enzymefor a variety of " unnatural " substrates may serve as a means of exploringthe immediate environment of the active centre; for, in general, substratespecificity and even product stereospecificity could be controlled by ob-struction of unfavourable structures or conformations, as well as by selec-tive binding of favourable ones.For example, glutamine synthetase 4O(from sheep's brain) converts both (R)- and (#)-glutamate into glutamines,but of the " unnatural " substrates (R)- and (S)-2-methylglutamate onlythe (&')-enantiomorph (78) was amidated. 3-Aminoglutarate is also a sub-.-4O H. M. Kagan, L. R. Manning, and A. Meister, Biochemistry, 1965, 4, 1063CORNFORTH AND RYBACK: STEREOSPECIFICITY OF REACTIONS 443strate for this enzyme and is converted, stereospecifically, into (3R)-3-aminoglutaramate (79) .41 These results were explained by supposing thatthe enzyme (since it does not amidate aspartate) imposes a fully extendedconformation on the glutaric acid chain in order that the two carboxylgroups shall be bound to the enzyme.Observing this condition, it i s possibleto arrange models of (Qglutamine, (R)-glutamine, and (3R)-3-aminoglu-taramic acid so that the carboxyl groups, the aminocarbonyl groups, and theamino-groups occupy essentially the same positions in space, but this is notpossible with (3S)-3-aminoglutaramic acid. In these models it could alsobe seen how an a-methyl group might prevent binding to the enzyme sur-face in the (R)- but not in the (8)- glutamic acid series.Oxido-reductases dependent on nicotinamide nucleotides have receivedspecial attention. Prelog 42 and his collaborators have studied the ratesand products of reduction of a large number of alicyclic ketones on horseliver alcohol dehydrogenase and on an extensively purified oxido-reductasefrom Curvularia falcatu, and have developed an ingenious system for sosynthesizing the results as to obtain a picture of the space available to sub-strates a t the active centre of the enzyme.Briefly, the configuration of theproduct alcohol is taken as more representative of the transition state thanthat of the substrate ketone; therefore, the hydroxyl group, the hydrogenatom introduced from the riucleotide, and the carbon atom to which they areboth attached are all given a fixed orientation. Molecular models of allproducts from substrates reducible by the enzyme are oriented in accordancewith those requirements, and a diamond-lattice skeleton is constructedwhich will just accommodate all their carbon atoms at lattice points.Asmore substrates are studied it may be possible to extend the lattice, and thestudy of non-reducible substrates which protrude from the lattice can beused to define regions where steric inhibition from enzyme or co-enzyme issevere. The limited number of conformations available to the alicyclicsubstrates limits also the alternative arrangements which have to be takeninto account. The lattice proposed for the Curvularia enzyme is shown inthe Figure.Laitice section (heavy lines) of oxido-reductwe f r m Curvularira falcata;42= '' forbidden position.' '41 E. Khedouri and A.Meister, J. Bid. Chm., 1965, 240, 3357.4a V. Prelog, Pure Appl. Chem., 1964, 9, 119444 BIOLOGICAL CHEMISTRYA similar approach has been used 43 to assemble the data obtained fromthe rates and products of reduction of cyclohexanones, 2-decalones, and10-methyl-2-decalones on liver alcohol dehydrogenase, and quantitativeinhibition factors were calculated for particular regions : this allowed pre-diction of rate and stereochemistry of reduction for a substrate not previouslyincluded in the lattice. A tentative orientation of the coenzyme in relationto the lattice was proposed. It will be interesting to see how far this approachcan be developed.43 J. M. H. Graves, A. Clark, and H. J. Ringold, Biochemistry, 1965, 4, 26553. THE MICROBIOLOGICAL DEGRADATION OF AROMATICCOMPOUNDSBy D.W. Ribbons(Milstead Laboratory of Chemkal Enzymology,“Shell ” Research Ltd., Sittingbourne, Kent.)IT is nine years since attention was focused on the microbiological oxidationof aromatic compounds in these Reports.1 Numerous major contributionshave considerably modified the general patterns of metabolism that hadbeen established; they have extended our knowledge of the mechmisms ofoxygenase reactions and clarified the ways by which the syntheses of theenzymes catalysing these catabolic reactions are controlled.It iscleu that catechol, protocatechuate, gentisate, and homogentisate are notthe only substances that are susceptible to ring fission; and, further, thatthe oxygenative cleavage of the former two compounds does not alwaysyield a muconic acid. Simple benzenoid compounds now known to yieldaliphatic compounds by oxygenase reactions also include 3-methylcate-~ h o l , ~ - ~ 4-methylcatechol,3-5 2,3-dihydro~yphenylpropionate,~~ homopro-tocatechuate,7~ quinol, hydroxyquinol, 9 and 2,3 -dihydroxybenzoate.l OOxygenations of catechol and protocatechuate are also catalysed by catechol2,3-oxygenase 2, 1 1 3 12 and protocatechuate 4,5-oxygenase 2,133 l4 to yieldsubstituted muconic semialdehydes.Several other enzymic reactions ofthis type are known to rupture the rings of condensed polynuclear aromatichydrocarbons and also those of some heterocyclic compounds, includingtryptophan and its metabolites.The purification and crystallization of some oxygenases has been mainlyresponsible for the progress of studies on the mechanism of their action.15The use of newer techniques of mass spectrometry and electron spin reson-ance spectroscopy has also largely contributed to success in this area.The analysis of the nature of the sequential induction and also repressionof the enzymes involved in some well-established pathways of metabolismW.C. Evans, Ann. Reports, 1956, 53, 279.S. Dagley, W. C. Evans, and D. W. Ribbons, Nature, 1960, 188, 560.H. Nakagawa, H. Inoue, and Y. Takeda, J. Biockm. (Japan), 1963, 54, 65.D. W. Ribbons, Proc. Internat. Congr. Biochem., New York, 1964.S. Dagley, P. J. Chapman, D. T. Gibson, and J. M. Wood, Nature, 1964,202,775.S. Dagley, P. J. Chapman, and D. T.Gibson, Biochim. Biophys. Acta, 1963,’ H. Eta, M. Kamimoto, S. Senoh, T. Admhi, and Y. Takeda, Biochem. Biophys.P. J. Chapman and S. Dagley, Biochem. J., 1960, 75, 6P.@P. Larway and W. C. Evans, Biochem. J., 1965, 95, 52P.lo D. W. Ribbons, J. @en. Microbiol., 1966, in the press: Biochem. J., 1966, inl1 S. Dagley and D. A. Stopher, Biochem. J., 1959, 73, 16P.l2 Y. Kojima, N. Itads, and 0. Hayaishi, J . Biol. Chem., 1961, 236, 2223.Is S. Trippett, S. Dagley, and D. A. Stopher, Biochem. J., 1960, 76, 20P.14D. W. Ribbons and W. C. Evans, Biochem. J . , 1962, 83, 482.l6 0. Hayaishi, Plenary Sessions 6th Internat. Congr. Biochem., New York City,Many alternative routes of metabolism have been discovered?78, 781.Res. Comm., 1965, 18, 66.the press.1964, I.U.B., 33, 31446 BIOLOGICAL CHEMISTRYhas been facilitated by more detailed kinetic studies, by the use of mutantsthat have deletions in the catabolic pathway, and by the use of gratuitous(non - meta boliz a ble ) inducers .I6 9 17The three main themes of this Report are: (a) alternative and generalpathways of metabolism; (b) oxygenases; and (c) regulation of the metabolicpathways involved.Pathways of Metabolism.-The methods by which benzenoid compoundsare dissimilated fall into two distinct classes: (a) cleavage of a catechol be-tween carbon atoms bearing hydroxyl groups, generally yielding 3-0Xoadi-pate, e.g., as shown in Scheme 1; and (b) cleavage of the ring between ahydroxylated carbon and a non-hydroxyhted carbon atom, generallyyielding pyruvate, e.g., as for gentisate oxidation or as shown in Scheme 2.Formation of 3-oxoadipate.In 1956, it was shown by Gross, Gafford,and Tatum l8 that the route of protocatechuate dissimilation to 3-oxoadipate(6) by extracts of Neurosporca crama was distinct from that utilized byPseudomonas putida A3. 12.19 (-)-p-Carboxymuconolactone (y-carboxyme-thyl-p- carboxy-Aa-butenolide) (1 1) is accumulated by purified extractsof N . crassn incubated with cis,cis-/?-carboxymuconate (9). This lactone isnot an intermediate for bacterial pathways. Neurospora and Pseudomonaspathways of protocatechuate degradation also Mered in the distributionof carbon atoms from protocatechuate into 3-oxoadipate (6). The C-3 of3-oxoadipate was derived exclusively from C-6 of protocatechuate inNeurospora but formed randomly from C-1 and C-6 of protocatechuate inPs.putidu A3.12. The possible symmetrical intermediates, &4ihydroxy-adipate and its di-y-lactone,20 were unable to act as precursors of 3-oxoadipatein the bacterial pathway, although the dilactone was non-enzymicallyisomerized a t pH values greater than 6.0 to (A)-muconolactone (a), and oneisomer of this was metabolized to 3-oxoadipate by Moraxella Iwofii Vibrio(O/l), Nocnrdia erythropolis, and certain pseudomonads but not by Ps.putida.20 ( + )-Muconolactone was isolated as a product of /I-carboxy-muconate metabolism by heat-treated extracts of M . Iwofii 21 and meta-bolized by untreated extracts to 3-oxoadipate. These results indicated amultiplicity of routes by which 3-oxoadipate could be formed from /I-carboxy-muconate : (i) via; p-carboxymuconolactone, (ii) via a symmetrical inter-mediate, and (iii) via a muconolactone.Scheme 1shows the pathway of /?-carboxymuconate metabolism to 3-oxoadipatethrough y-carboxymuconolactone (10) and this route may be common to all18 R.Y. Stanier, G. D. Hegeman, and L. N. Omston, “ Regulation chez les micro-orgtmisms,” Coll. Int. C.N.R.S., Marseilles, 1963, 227.17 J. Mandelstam, “ Regulation chez les micro-organisms,” Coll. Int. C.N.R.S.,Marseilles, 1963, 221.18 S. R. Gross, R. D. Gafford, and E. L. Tatum, J . Bid. Chern., 1956, 219, 781;E. L. Tatum and S. R. Gross, ibid., p. 797; S. R. Gross, ibid., 1959, 233, 1146.l9 D. L. MacDonald, R.Y. Stanier, and J. L. Ingraham, J . Bid. Chern., 1954, 210,809.8O €3. B. Cain, D. W. Ribbons, and W. C. Evans, Bkchem. J., 1961, 79, 312; S. R.Elsden and J. L. Peel, Ann. Rev. Microbwl., 1958, 12, 145.81 R. B. C&, Biochem. J., 1961, 79, 298.38 L. N. Ornston and R. Y. Stanier, Nature, 1964, 204, 1279: J . Biol. Chern., 1966,in the press.Ornston and Stanier 22 have now provided a clearer pictureRIBBONS : MICROBIOLOGICAL DEGRADAI'ION 4-47h (4) ccO4Non-enzymic IABacteria IA I \(7) (9) (1 '1Fungalbacteria, including Ps. M . Iwofii and putidcc. Furthermore, they haveelegantly elucidated the reactions leading to the formation of 3-oxoadipatefrom catechol which were not, until recently, entirely clear. The metabolismof catechol through &,cis-muconate (3) and ( +)-y-carboxymethy1-Aa-butenolide (4) was established in 1951,23 and the lactonizing and delactoniz-ing enzymes were separated.24 The delactonization of ( + )-muconolactone(4) was presumed to yield the enol form of 3-oxoadipate, possibly via, anenol-lactone (5).239 24 Formal proof of the participation of a second lactonehas now been provided.22 The enol-lactone, y-carboxymethyl- AD- buteno-lide (5) was isolated 22 as a product of cis,cis-/3-carboxymuconate (9) meta-bolism, using purified extracts of Ps.putidiz A3.12. Mutants (ELH-mutants) of this strain, which no longer contain the ferminal enzyme of thereaction sequences of Scheme 1 cannot form 3-oxoadipate from catechol.Extracts of benzoate-induced ELH- mutants do not accumulate 3-oxoadi-pate enol-lactone ( 5 ) when incubated with catechol or &,cis-muconate (3) ;instead (+ )-muconolactone (4) appears, suggesting that the equilibrium ofthe muconolactone-isomerase-catalysed reaction is almost completely infavour of (+)-muconolactone.These same extracfs also catalyse the con-version of 3-oxoadipate enol-lactone into a mixture of ( + )-muconolactoneand cis,&-muconate. The inability of ELH- mutants to grow on benzoateor p-hydroxybenzoate had suggested that the routes of 3-oxoadipate forma-tion from catechol or profocatechuate were convergent a t some point before3-oxoadipate. The common intermediate is the enol-lactone of 3-oxoadipate.W. C. Evans, B. S . W. Smith, R. P. Linstead, and J.A. Elvidge, Nature, 1951,168, 772.24 W. R. Sistrom and R. Y . Stanier, J . BioE. Chem., 1954, 210, 821448 BIOLOGICAL CHEMISTRYThe y-carboxymuconolactone proved to be too unstable to isolate asa product of 8-carboxymuconate metabolism. Its structure is deduced bythe ease with which the enol-lactone is formed non-enzymically by de-carboxylation, and also by its ultraviolet spectrum, which has a maximuma t 230 mp, somewhat higher than expected.It now seems that the isolation of (+)-muconolactone as a product ofprotocatechuate metabolism by extracts of M . Iwofii 21 and its non-enzymicformation from y-carboxymuconolactone 22 (10) was due to the activityof muconolactone isomerase which would cstalyse its formation from theenol-lactone.22 This enzyme is undoubtedly present in extracts of manybacteria induced to protocatechuate since muconolactone can act as aprecursor of 3-0xoadipate;~O furthermore, the enol-lactone hydrolase isparticularly thermolabile.Ps. putida A3.12 appears to be the exceptionsince extracts from uninduced cells of this strain do not catalyse the con-version of cis,&-muconate or muconolactone t o 3-oxoadipate.l8-20 Never-theless, the randomization of C-1 and C-6 of protocatechuate into C-3 andC-4 of 3-oxoadipate has been explained by the ready isomerization of theenol-lactone to muconolactone, and equilibration of this with cis,&-inuconate,22 which is the only symmetrical aliphatic compound in Scheme 1 ;i.e., the particular extracts used for the isotope experiments 18 may havebeen able to effect this equilibration.In N .crassa the formation of 3-oxoadipate from 8-carboxymuconolactone(11) is presumed to proceed via the enol-lactone ( 5 ) but this has not beendemonstrated. An intermediate between #I-carboxymuconolactone and theenol-lactone of 3-oxoadipate may be a carboxyenol-bctone since concomitantdecarboxylation during the formation of the enol-lactone ( 5 ) from 8-car-boxymuconolactone (11) is not a necessity as it is in the bacterial conversionof y-carboxymuconolactone (10) into the enol-lactone (5) of 3-oxoadipate.3-Oxoadipate is also a product of hydroquinone metabolism by bacteria.9Extracts of a soil pseudomonad were able to cleave the nucleus of quinol andtransform the product, y-hydroxymuconic semialdehyde, to 3-oxoadipate.Pormation of pyruvute. Bacteria: and possibly other micro-organisms,25are able to form aliphatic compounds from catechol and protocatechuateby a second mode of ring fission. Thus, the enzymes catechol 2,3-osy-genase 2,119 12926 and protocatechuate 4,5-oxygenase,29 14, 2 7 open the nucleusof their substrates to form substituted muconic semialdehydes.Pyruvatewas shown to arise from these intermediates. This route of degradation isgenerally easily recognized by two characteristics : (a) the initial products ofring fission, the muconic semialdehydes, are bright yellow a t neutral andalkaline pH values, and ( b ) these products react non-enzymically withammonium ions to form pyridine carboxylic acids (Scheme 2, Table 1).Theformer property has been used as a spot test for the presence of catechol2,3-oxygenase 28 and protocatechuate 4,5-oxygenase 2 9 in whole cells.2 5 R. F. Bilton and R. B. Cain, J . Gen. Microbiol., 1966.26 S. Dagley and D. T. Gibson, J . BioE. Chern., 1964, 239, PC 1284; S. Dagley and27 S. Dagley and M. D. Patel, Biochem. J., 1957, 66, 227.28 E. S. Pankhurst, J . Appl. Bmteriol., 1965, 28, 309.* @ N. J. Palleroni and R. Y. Stanier, J. Ben. Microbiol., 1964, 35, 319.D. T. Gibson, Biochem. J., 1965, 466RIBBOXS : MICROBIOLOGICAL DEGRADATIOF 449Although the discovery of the meta-fissions is relatively recent, it is clearthat they are widespread and that the enzyme-catalysed reactions leading topyruvate from different ring-cleavage substrates are of a similar type, andmay be presented in a general pattern as seen in Scheme 2, and Table I(p.450). Dagley, Chapman, Gibson, and Wood have established thisR' * COzH R'R'C02HI,co M e (16)general metabolic route for catechol,59 26 3-methylcatechol, 4-methylcate-ch0l,5 protocatechuate,5 2,3-dihydroxyphenylpropionate,5, 6 , 3O and 3,4-dihydroxyphenylacetate.31 It is evident that all these substrates are noteatabolized by the same series of enzymes, although there is evidence thatsome of the enzymes that catdyse these analogous reaction sequences arenot specific. Catechol, 3-methylcatechol, and 4-methylcatechol may forma group that are catabolized by the same series of enzymes. The specificityof catechol 2,3-oxygenase does not, however, extend to protocatechuate,2,3-dihydroxyphenylpropionate9 or homoprotocatechuate, which are oxidizedby protocatechuate 4,5-oxygenase,14 2,3-dihydroxyphenylpropionate oxy-genase,6? 31 and 3,4-dihydroxyphenylacetate 2,3-oxygenase or 3,4-dihy-droxyphenylacetate 4,5-0xygenase,~O respectively. Similarly, the aldolasethat splits y-hydroxy-a-oxovalerate to acetaldehyde and pyruvate (as forexample in the sequence for catechol) is distinct from that which forms twomolecules of pyruvate from one molecule of y-hydroxy-y-methyl-a-oxoglu-tarate (part of the reaction sequence for protocatechuate oxidation).Dis-crimination between the ring-cleavage oxygenases may also be made by theease wit'h which some of them are dissociated from the Fez+ ions essential totheir activity.Catechol2,3-oxygenase,l5 protocatechuate 4,5-oxygenase,l*, 272,3-dihydroxyphenylpropionate oxygenase, and 3,4-dihydroxyphenylace-tate 4,5-oxygenase 30 are easily resolved from Fez+ ions by precipitationwith ammonium sulphate or by dialysis; but only prolonged storage or treat-ment with hydrogen peroxide produms in 3,4-dihydroxyphenylacetate2,3-oxygenase the requirement for added Fe2f.Although the integrating rbles of 3-oxoadipate and pyruvate are wellestablished for many reaction sequences leading from the benzene nucleus,these two metabolites are not always the earliest common intermediates ofchemically analogous pathways. For pathways involving " cis,cis-muconic30 S. Dagley, P. J. Chapman, and D.T. Gibson, Biochem. J., 1965, 97, 643.31 S. Degley and J. M. Wood, Biochim. Biophys. Acta, 1965, 99, 383; S. Dagley,J. M. Wood and P. J. Chapman, Biochem. J . , 1962, 84, 9PPTABLE 1 Intermediates formed during metabolism of substituted catechols byRing-cleavage substrateCatechol3 -Methylcatecho14-Methylcatechol2 , 3 -Dihydr oxy - /3-phenyl-propionateProtocatechuate3,4 -Dihydroxyphenylacetate3,4-Dihydroxyphenylacetateandrosta-1,3,5( 10)-triene-9,17-dione (29a)3,4-Dihyclroxy-9, ~ O - S ~ C O -RlHMeHHHSee (a)in Scheme 4R2HHMeHHHCH2C02HMeR,HHHHCO,HCH2C02HHHHydroxy -acidMoiety (14)y-Hydroxy- a-oxo-valeratey-Hydroxy- a-oxo-valerate~-HY&OXY- a-oxo-caproatey-Hydr~xy- a-oxo-valeratey-Hydroxy - y-methyl-a-oxoglutaraMhydroxy- a-oxovalerate[ pimelatecaproatey-Cmbox~thyl-y-1 y-Hydroxy- a-0x0-~-HY&oxY- a-OXO-AcidFormateAcetateFormateSuccinateFormateFormate[FormateRIBBONS : MICROBIOLOUICAL DEURADATION 451acids," the enol-lactone of 3-oxoadipate is the first common intermediate ofcatechol and protocatechuate metabolism (Scheme 1) ; for reaction sequencesof the type shown in Scheme 2, y-hydroxy-cc-oxovalerate is the fist commonintermediate arising from catechols where R2 and R3 are hydrogen atoms.The formation of y-hydroxy-cc-oxovalerate occurs independently of the sub-stituent a t R1, be it hydrogen, methyl, or p-propionyl, since the carbonatom to which it is attached is separated as a carboxylic acid from the restof the carbon atoms derived from the benzene nucleus (Scheme 2).The enzymes, first extracted from pseudomonads by Dagley et aZ.cata-lysing the conversion of catechol into formate, acetaldehyde, and pyruvateand the conversion of 2,3-dihydroxyphenylpropionate into succinate, acetal-dehyde, and pyruvate have been studied in more detail.26s31 The aldolasewhich, in both enzyme sequences, catalyses the formation of acetaldehydeand pyruvate from one of the enantiomers of y-hydroxy-cc-oxovaleraterequires Mg2+ ions for high activities; the Achromobackr enzyme (2,3-dihydroxyphenylpropionate sequence) also responds to Mh2+ ions but theseare not as effective as Mg2+ ions.3lIt is well established that catechol, the methyl-substituted catechols, andprotocatechuate may be oxygenated a t two different sites; however, the twodistinct sites of cleavage on the 3,4-dihydroxyphenylacetate molecule areboth meta to the o-dihydroxy-group.Products of both enzymic reactionshave been characterized as derivatives and the sites of cleavage determinedby the formation of characteristic pyridine carboxylic acids by non-enzymicreaction with NH,+ ions. The muconic semialdehyde, obtained from thereaction catalysed by the 2,3-oxygenase, yielded with NH,+ ions a carboxy-methylpyridinecar boxylate oxidized by permanganat e to p yridine -2,s-dicarboxylate 32 (23) whereas the 4,5-oxygenase-catalysed reaction gave in t'heOHA I- 2,3-OxygenaseB = 4,s -0xygenases2 K. Adachi, Y.Takeda, S. Senoh, and H. Eta, Bwchim. Bhphgs. Acta, 1964,93, 483452 BIOLOGICAL CHEMISTRYsame way an isomeric carboxymethylpyridinecarboxylate (25) decarboxyl-ated to pyridine-4-acetic acid (26) 3O (Scheme 3).The Pseudomoms studied by Hayaishi and co-workers1~ appears toutilize an alternative route for a-hydroxymuconic semialdehyde metabolismto that established by Dagley et aL5 (Scheme 2). The sequential formation of4- oxalocr otonate , 4 - hydroxy-2 - oxovalerate , ace t o p yr uvat e, and acetate pluspyruvate was proposed. The enzyme decarboxylating 4-oxalocrotonate t o4-hydroxy-2-oxovalerate was also present in extracts of other bacteria thatmetabolize catechol to pyruvate without carbon dioxide ev~lution,~ i.e.,according to Scheme 2.Enzymes that decarboxylate 3-oxoglutarate occurin Pseudomanas induced to oxidize homoprotocatechuate (4,5-fission) byreactions of Scheme 2 , 6 9 30 but 3-oxoglutarate is not an intermediate.30Furthm examples of the general pathway illustrated in Scheme 2 are tobe found amongst micro-organisms degrading the A ring of certain steroids.Cleavage of ring A of steroids. The microbiological transformation ofsteroids has received special attention, mainly because of commercial pros-pects. Many of these are oxygenative reactions where hydroxyl groups arestereospecifically introduced into almost any position of the nucleus (forReview see Hayano 33). Less widespread, however, are ring-cleavage oxy-genases. Sih and Wang 34 and others 35 showed that androst-4-ene-3, 17-0 nCHO MeMe I + ':--- pMeC? CO2H iCH y x k r M eI- CPH/ * CO2HR(32)('33) Pe + C3 fragmentMef- -HZN COZH A H2N CO2H(3 5 )R = 0f--0 NMeR(3')H2C H2C3 3 M.Hayano, " Oxygenases," ed. 0. Hayaishi, Academic Press, New York, 1963,3 4 C. J. Sih and K. C. Wang, J . Amer. Chem. Soc., 1963, 85, 2136.35 R. M. Dodson and R. D. Muir, J . Amer. Chem. Soc., 1961, 83, 4627.p. 181R I B B O N S : MICROBIOLOGICAL DEGRADATION 453&one (27) was converted into perhydro-7ap-methyl- 1,5-dioxo-lH-3a~-indane-4-propionic acid (32; R = a) via the seco-phenol, 3-hydroxy-9,lO-secoandrosta- 1,3,5( 10)- triene-9,l'l-&one (28) by Pseudomonas sp., Myco-bacterium smegmatis, and Nocurdia restrictus. Cleavage and loss of the Catoms of the A ring of the seco-phenol had clearly occurred.3,4-Dihy-d.roxy-9,10-secoandrosta-1,3,5( IO)-triene-9,17-dione (29; R = a) was alsooxidized to the acid (32; R = a). 4-Hydroxy-2-oxocaproic acid (as thelactone) (34) and 4(5), 9( l0)-diseco-3-hydroxyandrosta-l( 10),2-diene-5,9,17-trion-4-oic acid (30; R = a) were detected as intermediates, and thelatter (30; R = a) was converted non-enzymically with ammonia into itspyridine compound ( 3 1 ) . 3 s y 37 The reactions shown in Scheme 4 (29)-(33)are chemically analogous to those in Scheme 2. A similar series of reactionswould also account for the conversion of progesterone into l-acetylperhydro-7a~-methyl-5-oxo-1H-3aa-indane-4-propionic acid (32 ; R = b) by M . smeg-m~tis.~* The degradation of androst-4-ene-3,17-dione (27) by Ps.testo-steroni, however, yields 2-amino-cis-hex-4-enoate (35) and alani1.1e.3~ Re-actions leading to these compounds are also shown in Scheme 4.Oxidative metabolism of condensed polynuclear aromatic compowzds. Thissection logically follows the last since reactions which degrade condensedpolynuclear aromatic compounds (Scheme 5) are similar in many respects tothose which degrade catechol to pyruvate, as shown in Scheme 2, once the" polynuclear 1,2-diol" has been formed. Thus, oxygenative cleavage ofX\/-.Y k'R2 "'0HO(43)(3 7) (38)Repeat sequenc3 Afor phe5anthrGne/R'OHd C02H z(42)enzymicCHO(41) + fO2H ' 0.co Me\\A Maleylpyruvatefrom 2-naphthoI?36 C. J. Sih, S. S.Lee, Y . Y . Tsong, and K. C. Wang, J . Amer. Chem. SOC., 1965,37 C. J. Sih, K. C. Wang, D. T. Gibson, and H. W. Whitlock, jun., J . Amer. Chem.38 K. Schubert, K.-H. Bohme, and C. Horhold, 2. physiol. CJzem., 1961, 325, 260.3s D. A. Shaw, L. F. Borkenhagen, and P. Talalay, Proc. Nut. Acad. Xci. U.S.A.,87, 1385.SOC., 1965, 87, 1386.1965, 54, 837454 BIOLOGICAL CHEMISTRYthe '' catechol " ring occurs between carbon atoms 1 and 8a, to yield a sub-stituted enol-pyruvate. The next established product is a, substitutedsalicylaldehyde (41) formed by loss of a C3 fragment as pyruvate. If theformation of the aldehyde and pyruvate occur by mechanisms similar tothose in Scheme 2, hydration a t C-3 and C-4 would occur, followed by aretro-aldol fission.It is possible that a complete analogy with the reactionsdiscovered by Dagley et aL6 (Scheme 2) occurs in the degradation of poly-nuclear compounds. Ruptureof the substitutingring in Scheme 5 between car-bon atoms 4a and 8a of structure(40), loss of pyruvate from the hydrated pro-duct, and aromatization of the substituting ring would yield a salicyaldehyde.The general scheme presented for the dissimilation of polynuclear com-pounds seems to account for all the observations so far made for naphthaleneand various substituted derivatives. Table 2 includes the details of theintermediates established for the various polynuclear growth substrates.The most thorough studies to date, in accord with this scheme, have beenmade by Davies and Evans4* for naphthalene and Evans, Fernley, andGriffiths 41 for phenanthrene and anthracene.Pseudomonads that havebeen grown on napthalene as sole source of carbon release small quantities ofD-trans-lY2-dihydro-1,2-dihydroxynaphthalene 42 and salicylate 439 44 into themedium. Extracts of these cells cleave the hydroxylated ring of 1,2-dihy-droxynaphthalene with the consumption of one mole of oxygen per mole ofthe diol ; the product, cis-o-hydroxybenzalpyruvate, was isolated as thepyrylium perchlorate salt. The ease with which this intermediate formscoumarin now explains the earlier observations upon the accumulation ofcoumarin in culture fluids and during enzymic oxidation of 1,2-dihydroxy-naphthalene.45 Carbon dioxide is not evolved enzymically during the meta-bolism of l ,2-dihydroxynaphthdene, but only when conditions permitlactonization, e.g., a t low pH values.o-Hydroxybenzalpyruvate is degradedto pyruvate and salicylate by an NAD specific dehydrogenase. a-Hydroxy-muconic semialdehyde (Scheme 2), the product of catechol cleavage by the2,3-ouygenase, is formed from naphthalene, salicylate, and catechol withcells that have been aged or stored at - 15". Epoxidation of the naphthalenering is probably the initial stage of naphthalene degradation, followed by atrans-hydration of the epoxide to form the dihydro-diol; high-speed super-natant fractions of extracts obtained from pseudomonads grown on naptha-lene when supplemented with NADH, glutathione (reduced), alcohol, andexcess of alcohol dehydrogenase yield the dihydro-diol. This is metabolizedfurther, upon addition of NAD, to cis-o-hydroxybenzalpyru~afe.~~ All ofthe naphthalene-utilizing organisms so far examined appear to follow thispathway;40 thus, the tentative identification of 3-oxoadipate as a meta-bolite of naphthalene 47 and its inclusion in metabolic maps, requires furtherinvestigation.4 O 6.I . Davies and W. C. Evans, Biochem. J., 1964, 91, 251.4 1 W. C. Evans, H. N. Fernley, and E. Grifliths, Biochsrra. J., 1965, 95, 819.43 N. Walker and G. H. Wiltshire, J . Gen. Mdwobiol., 1953, 8, 273.43 R. J. Strawinski and R. W. Stone, J . Bacterial., 1943, 45, 16.44 V. Treccani, Ann. Microbiol., 1953, 5, 232.L6 H. N. Fernley and W. 0. Evans, Nature, 1958, 182, 373.4 e E .Graths and W. C. Eva-, Bwchem. J., 1965, 95, 51P.47 J. F. Murphy and R. W. Stone, Canad. J . Microbwl., 1955, 1, 579Polynuclear carbon sourceNaphthalene1 -Chloronaphthalene2-Chloronaphthalene1 -Brornonaphthalene1 -Methylnaphthalene2 -Methylnaphthalene2 -Hydroxymethylnapthalene2 -Methoxynaphthalene2-E thoxynaphthalene2-HydroxymphthalenePhenanthreneAnthraceneTABLE 2 Cmpounds isolated as metabolites of polynuclearSubstituents forScheme 3R' R' R8H H Hc1 H HH c1 HBr H HMe H HH Me HH CH,OH HH Me HH OEt HH OH HCH:CH*CH:CH HH :CH.CH :CHDihydro-diol42596059505161Products40, 42,59605950, 6464, 5667484858(a) 1-HY~~(b) Salicylate(a) 3-HY~~(b) Salicylatenaphthoatenaphthoat456 BIOLOGICAL CHENISTRYScheme 5 does not account for all the metabolites found during dissimi-lation of 2-methylnaphthalene by Pseudomonas aeruginosa 54 and otherbacteria.57 An alternative pathway exists in which the methyl group isoxidized to carboxyl.The further met'abolism of 2-naphthoate remains to beelucidated, although precursors of it apparently participate in reactionsdepicted in Scheme 5It seems that only mono-nuclear hydrocarbons are degraded to 3-oxoadipate by various species ofbacteria. Ps. aeruginosa, Mycobacterium rhodochrons, and Nocardia sp.oxidize benzene via catechol and &,cis-muconate to 3-oxoadipate.62-6*The trans-diol, cyclohexa-3,5-diene-1,2-diol, is suspected of being inter-mediate between benzene and catechol ; extracts of Aerobncter aerogeneshave been shown to catalyse dehydrogenation of this compound to cate-ch01.~~ Epoxidation of benzene may precede formation of the diol, butproof of these steps is lacking.trans-trans-Muconate has been isolated as ametabolite in Micrococcus sphaeroides 66 and Nocardia corallina,66-6B sincethe stability of the isomers of the muconic acids was elucidated;23 the routeof its formation, as in animals,6g remains to be investigated.The degradation of alkylbenzenes has been little studied, except fortoluene. The ability of Ps. aeruginosa to oxidize benzyl alcohol, benzalde-hyde, benzoate, and catechol, only when the cells had been exposed totoluene suggests that side-chain oxidation occurs before ring cleavage.iOSuch a pathway is however not ubiquitous;70-72 Claus and Walker i2 havedemonstrated that other pseudomonads yield different enzyme systems tometabolize toluene.Extensive whole-cell experiments with Achromobactersp. and Pseudomonas sp. grown on toluene, benzyl alcohol, or benzene showthat benzaldehyde and benzoate are not metabolized except after a period48 R. J. W. Byrde, D. F. Downing, and D. Woodcock, Biochem. J., 1959, 72, 344.4 9 C. Colla, C. Biaggi, and V. Treccani, Atti Acad. naz. Lincei, Rend. Classe Sci.50 L. Canonica, A. Fiecchi, and V. Treccani, Rend. Inst. Lombard0 Sci. Lettere, B,61 C . Colla, A. Fiocchi, and V. Treccani, Ann. Microbiol. Enzimol., 1959, 9, 87.5 2 M. H. Rogoff and I. Wender, J . Bacteriol., 1957, 73, 264.53 M.H. Rogoff and I. Wender, J . Bacteriol., 1957, 74, 108.5 4 M. H. Rogoff and I. Wender, J . Bacteriol., 1959, 77, 783.5 6 V. Treccani and G. Baggi, Rend. Inst. Lombard0 Sci. Lettere, B, 1962, 96, 32.5 6 JT. Treccani and A. Fiecchi, Atti IX Congr. Naz. Microbiol. Palermo, 1956, 139.j7 V. Treccani and A. Fiecchi, Ann. Microbiol. Enzimol., 1958, 8, 36.58 K. Walker and K. D. Lippert, Biochenz. J., 1965, 95, 5C.j 9 X. Walker and G. H. Wiltshire, J . Gen. Microbiol., 1955, 12, 478.6o C. Arnaudi and V. Treceani, Sci. Reports Ist. Super. Sanitd, 1961, 1, 378.61 V. Treccani, Progress Indust. Microbwl., 1962, 4, 3.6 2 A. C. Van Der Linden and G. J. E. Thijsse, Adv. Enzymol., 1965, 27, 469.63 E. I<. Marr and R. W. Stone, J . Bacterwl., 1961, 81, 425.6 4 V.Treccani and B. Bianchi, Atti X Congr. Naz. Microbiol., 1959, 207.6 5 P. Iz. Ayengar, 0. Hayaishi, M. Nakajima, and T. Tomida, Biochirn. Biophys.6 6 A. Kleinzeller and Z. Fend, Chem. Abs., 1953, 47, 4290.67 T. Wieland, G. Griss, and B. Haccius, Arch. Mikrobiol., 1958, 28, 383.68 B. Haccius and 0. Helfrich, Arch. Mikrobiol., 1958, 28, 394.69 D. V. Parko and R. T. Williams, Biochem. J., 1954, 51, 339.7o 31. Kitagawa, J . Biochem., 1956, 43, 653.71 J. R. Forro and R. W. Stone, Bact. Proc., 1965, 90.7 2 D. Claus and N. Walker, J. Gen. Microbiol., 1964, 38, 107.(Table 2).-Metabolism of other aromatic hydrocarbons.$8. mat. nut., 1957, 23, 66.1957, 91, 119.Acta. 1959, 33, 111RIBBONS : MICROBIOLOGICAL DEGRADATIOK 457of induction, although these cells contain enzyme systems of low specificity.Furthermore, 3-methylcatechol was detected as a metabolite of toluene, andwas oxidized by cells taken from toluene media but not by those harvestedfrom catechol media. The pathway of toluene degradation is not yet entirelyclear, although a route through 3-methylcatechol and fissions according toreactions of Scheme 2 might be suggested, since yellow 0x0-acids, acetate,and pyruvate have also been detected as metabolite^.^^ Further supportfor such a scheme comes from the isolation of glycollic acid as a metaboliteof benzyl alcohol in toluene-grown cells.The hydroxymethyl group wouldbe RI in Scheme 2 and the unidentified phenol in culture filtrates may be2,3-dihydroxybenzyl alcohol.Extracts obtained from a toluene-grownpseudomonad degrade toluene and 3-methylcatechol to a compound withspectral properties similar to 2-hydroxy-6-oxohepta-2,4-dienoate (13 ;R1 = Me);10, 7l benzaldehyde, benzoate, and catechol, however, yielda-hydroxymuconic semialdehyde (13).Very little is know-n about the microbial oxidations of other alkylben-zenes. Nocardia sp. which oxidize decyl- dodecyl-, and octadecyl-benzenesyield phenylacetic acid ;73 ethyl and n-butylbenzenes also yield this productwhen they are used to supplement media containing n-alkanes, but they donot support growth.'4 Alliylbenzenes containing an odd number of carbonatoms yield cinnamic acid.74MetaboEism of tryptophan. Pseudomonads are known to degrade trypto-phan to carbon dioxide, water and ammonia by two main routes called (a)the aromatic pathway and (b) the quinoline pathway (Scheme 6).The mainsteps of the aromatic pathway were established 75 before 1951, but elucida-tion of the route of kynurenic acid degradation is comparatively recent.Invariably micro-organisms that utilize the quinoline pathway can oxidizeD-tryptophan as well as the L-isomer. The D-isomer is metabolized by itsown stereospecific enzymes to kynurenic acid (49) ; 76 the final stage is cata-l>-sed by D-kynurenine oxidnse, and this reaction is distinct from the transa-mination of L-kynurenine (46) to kynurenic acid (49). Behrman 77 isolateda pseudomonad that oxidized tryptophan by the aromatic pathway andutilized D-tryptophan. A tryptophan racemase was demonstrated in thisorganism, and D-kynurenine is not metabolized.A third pathway is sug-gested for Fhuobacte~ia metabolizing D-tryptophan. 78 Electron acceptors,such as phenazine methosulphate, are required in addition to an amino-groupdonor. Formation of indolepyruvic acid and transamination to L- tryptophanappear to occur.The quinoline pathway of tryptaphan metabolism was discovered whenextracts of cells supplemented with reduced coenzymes yielded L-glutamate,D- and L-alanine, acetate, and carbon dioxide, and it was found that the73 D. M. Webley, R. B. Duff, and V. C. Farmer, Nature, 1956, 178, 1467.73 J. B. Davis and R. L. Raymond, AppZ. Microbiol., 1961, 9, 383.7s R. Y. Stanier and 0. Hayaishi, Science, 1951, 114, 326.76 M.Tashiro, T. Tsukada, S. Kobayashi, and 0. Hayaishi, Biochem. Biophya.7 7 E. J. Behrman, Nature, 1962, 196. 150.Res. C'omm., 1961, 6, 155.'* J. R. Martin and K. N. Durham,- Biochem. Biophp. Res. Comm., 1964, 14,388458 BIOLOGICAL CHEMISTRY+ NH3Q U i no I i ne pathwayglutamate was derived from the carbocyclic ring.79-81 The intermediates7,8- dihydroxykynurenate ( 5 1 ) , 5- ( y - carboxy- y - oxopropyl) -4,6-dihydroxy-picolinate (53), 5- (p-formylethyl) -4,6-dihydroxypicoliate (54), and 5- (p-carboxyethyl)-4,6-dihydroxypicolinate (55) have apparently been charac-terized for Pseudomom sp . , 82y 83 and 5 - ( y - carb oxy - y - oxopropenyl) -4,6 -dihydroxypicolinate (52) and the acid (55) for an Aerococcus 84 metabolizingkynurenic acid.It seems likely that a 7,8-epoxide is intermediate betweenkynurenate and the dihydro-diol (50) as for naphthalene metabolism.Experiments using l 8 0 support this v i e ~ . ~ 3 The origin of the end productsof this reaction scheme is less clear, Kuno et aZ.82 have demonstratedstoicheiometric formation of a-oxoglutarate, ammonia, and oxaloacetatefrom 5-(~-carboxyethyl)-4,6-dihydroxypicolinate (55) ; extracts of Aero-coccus also yield glutamate, aspartate, and pyruvate. 84 The enzyme systemsfor this dissimilation are obviously still too crude to yield a definitiveanswer.For pseudomonads that utilize the aromatic pathway, the formation of7B E. J. Behrman and T. Tanaka, Biochem. Bwphys. Res. Comm., 1959, 1, 257.0. Hayaishi, H. Taniuchi, M.Tashiro, and S. Kuno, J . BioE. Chem., 1961, 238,81 K. Horibata, H. Taniuchi, M. Tashiro, S. Kuno, and 0. Hayaishi, J . BioE. Chem.,88 S. Kuno, M. Tashiro, H. Taniuchi, K. Horibata, 0. Hayaishi, S. Senoh, T.e8 H. Taniuchi and 0. Hayaishi, J . BioE. Chem., 1963, 238, 283.84 S. Dagley and P. A. Johnson, Biochim. Biophys. Acta, 1963, '78, 577.2492.1961, 236, 2991.Tokuyama, and T. Sakan, Fed. P~oc., 1961, 20, 3RIBBONS : MICROBIOLOGICAL DEGRADATION 459catechol from anthranilate appears to be the only established route. How-ever, an alternative route of anthranilate metabolism is exhibited by a soilAchromobacter sp ; 5-hydroxyanthranilate and gentisate are implicated asintermediates in this pathway.", 86 Phvobacteria, after growth on anthra-nilate, oxidize sali~ylate.~'Metabolism of phenylpropanoid structures.Although a high proportionof organic carbon is returned to the soil as phenylpropanoid structures, thereis little detailed information as to how these compounds are metabolized.Specific studies have been made on the microbial degradation of phenyl-propionate, cinnamate, and coumarin.Some species of Arthrobacter utilize coumarin as sole source of carbon;88changes in ultraviolet absorption and chromatographic characteristics sug-gested that o-coumarate and melilotate (o-hydroxyphenylpropionate) weremetabolites. o-Coumarate is reduced to rnelilotate by an NAD or NADPoxidoreductase which is present in cells only after growth on o-coumarate.2,3-Dihydroxyphenylpropionate has also been tentatively identified as aproduct of melilotate when incubated with crude extracts and NADH.89,It would be of interest to know if 2,3-dihydroxyphenylpropionate is meta-bolized by reactions shown in Scheme 2 by Arthrobacter sp.Growth of pseudomonads on cinnamate generally yields cells able tomet a b olize p henylpropionate .Melilot at e and 2,3 -dihydr ox yphenylpr o -pionate have been isolated from culture filtrates of cinnamate 91, 92 andphenylpropionate media.32 Reduction of this side-chain appears to befairly widespread, since cinnamate, .Q-hydroxyci~amate, and 3,4-dihydroxy-cinnamate yield their respective dihydro-compounds from media supportingthe growth of Lactobacillus pastorknus par. q u i n i c ~ s . ~ ~ Phenylpropionicacid has also been detected as a metabolite of cinnamate by Pseudomonas;92hydroxylation of the ring a t position 3 before reduction of the side-chain hasalso been suggested for this strain;92 in this respect, it is interesting to notethat the specscity of 2,3-dihydroxyphenylpropionate 2,3-oxygenase extendsto 2,3-dihydroxycinnamate.In addition to these reactions, substitutedphenylpropanoid compounds are decarboxylated to yield their phenylethanesand styrenes by L. pastorianum 93 and Aerobacter,g* respectively.Studies on the bacterial degradation of lignans and other lignin-relatedcompounds have also been rep0rted,~5 and in some detail for Agrobac-t e r i ~ . ~ ~ , 97 a-Conidendrin-degrading Agrobacteria oxidize several otherlignans indicating low specificity of response to the inducer.Sequential85 J. N. Ladd, Nature, 1962, 194, 1099.86 J. N. Ladd, Austral. J. BioZ. Sci., 1964, 17, 153.87 T. Higashi and Y. Sakamoto, J. Biochern. (Japan), 1960, 48, 147.C. C. Levy and G. D. Weinstein, Nature, 1964, 202, 596.C. C. Levy and (3. D. Weinstein, Biochemistry, 1964, 3, 1944.C. C. Levy, Nature, 1964, 204, 1059.C. B. Coulson and W. C. Evans, Chern. and Id., 1959, 643.8a E. R. Blakley and F. J. Simpson, Canad. J. Microbiol., 1964, 10, 175.g3 G. C. Whiting and J. G. Cam, Nature, 1959, 184, 1427.Q 4 B. J. Finkle, J. C. Lewis, J. W. Corse, and R. Lundin, J. Biol. Chem., 1962, 237,96 H. Ssrensen, J. Gen. Microbiol., 1962, 2'7, 21.V. Sundman, J . Gen. MicrobioE., 1964, 36, 185.97 V. Sundman, J. Ben. MicrobioE., 1964, 36, 171.2926460 BIOLOGICAL CHEMISTRYinduction experiments suggest that or-conidendrol is an intermediarymetabolite of a-conidendrin. Extracts of these organisms should yield avariety of interesting new enzymes.Oxygenases Involved in Aromatic Ring Metabolism.-The progress madein the elucidation of the mechanisms of oxygenase reactions is almost en-tirely due to the admirable researches of Hayaishi and his colleagues.lj9 98The demonstration that pyrocatechase catalysed the incorporation of bothatoms of a molecule of oxygen into the carbon substrate to yield labelledmuconic loo and that phenolase catalysed the incorporation ofmolecular oxygen into an aromatic substrate in the presence of reducingsubstances,lol initiated the studies on oxygenase reactions.A particularlygood account of oxygenases has been published by Hayaishi.ls During thepast two years three ring-cleavage enzymes, pyrocatechase,lo2 catechol2,3-oxygenase,lo3* lo4 and 3,4-dihydroxyphenylacetic acid 2,3-oxygensse 7, lo5have been crystallized. The problems of instability that previously pre-cluded such purifications were solved by maintaining the enzymes in areduced condition, notably with sodium borohydride under anaerobic con-ditions,lO6j 107 and by protecting them against inactivation by air in thepresence of organic solvents.Cadecho1 1,2-oxygenase (pyrocatechase) . This has been extensively purifiedand crystallized,15, loa the final preparations being homogeneous in theultracentrifuge and upon electrophoresis. Molecular weights of 95,000,108&4,OOOY1O9 and 78,0003 are reported for preparations from Pseudomonus,Micrococcus, and Brevibacterium, and for Pseudomonas pyrocatechase twoatoms of iron are bound to each protein molecule. No other cofactors havebeen found.Although this enzyme was the first of its type discovered, theactual demonstration of an Fe2+-ion requirement has been diffcult and con-fusing. Suda and co-workers have removed Fe2+-ion with o-phennn-throline from pyrocatechase obtained from Psedmonas sp. and reactivatedthe enzyme with Fe2+. They also demonstrated that an enzyme preparationMicrococcus ureae was able to exchange its protein-bound Fe2+ with eso-genous 59Fe2f only when both substrates (cstechol and oxygen) were pre-88 0.O9 0.loo 0.l01 H.2914.102 Y.1963, 85,Io3 M.1963, 11,lo4 M.lo6 H.100 0.lo’ H.Biop h ya.lo8 H.829.lo9 K.5450.Hayaishi, ‘‘ Oxygenases,” Academic Press, New York, 1962.Hayaishi, M.Katagiri, and S. Rothberg, J . Amer. Chem. SOC., 1955, 77,Hayaishi, M. Katagiri, and S. Rothberg, J . Biol. Ckem., 1957, 229, 905.S. Mason, W. L. Fowlks, and E. Peterson, J . Amer. Chem. SOC., 1955, 77,Kojima, J. Nakazawa, H. Taniuchi, and 0. Hayaishi, J . Jap. Biochem. SOC.639.Nozaki, H. Kagamiyama, and 0. Hayaishi, Biochem. Biophya. Res. Crnnm.,65.Nozaki, H. Kagamiyama, and 0. Hayaishi, Biochem. Z., 1963, 388, 582.Kita, J . Biochem. (Japan), 1966, 58, 116.Hayaishi, H. Taniuchi, and Y. Kojima, Fed. Proc., 1962, 21, 52.Taniuchi, Y.Kojima, F. Kanetsuna, H. Ochiai, and 0. Hayaishi, Biochem.Res. Comm., 1962, 8, 97.Taniuohi, Y. Kojima, A. Nakazawa, and 0. Hayaishi, Fed. Proc., 1964, 23,I Tokuyama, M. Suda, and Y. Shimomura, Proc. Internat. Symp. EnzymeM. Suda, K. Hashimoto, H. Matsuoka, and T. Kamahora, J . Biochem. (Japan),Chem., Japan, 1957, 197.1951, 38, 289RIBB ON S : MICROBIOLOGICAL DEGRADATION 461sent, and the rate of exchange was a function of the rate of enzymic reactionoccurring.l*s The exchange data indicated that this pyrocatechase was ableto exchange only one atom of iron per molecule of protein.Pyrocatechase obtained from Ps. arlviWct is red, with a broad absorptionband between 400 and 600 mp, and its e.s.r. spectrum shows a sharp linea t g = 4.2 and a signal width of 35 gauss between the peaks.1ll Dithioniteabolishes the visible and e.s.r.spectra, both of which are partially re-stored by oxygenation. These results indicate the presence of one Fe3+ ionbound to each protein molecule. Protein-bound Fez+ ion could not bedetected spectroscopically even with dithionite-reduced enzyme, althoughchemical analysis was positive. A correlation between bound Fe3+ ion,visible absorption spectra, and enzymic activity was found during varioustreatments. Addition of catechol to the enzyme (anaerobic) abolishes thee.s.r. signal but the 400-600-mp spectrum is retained and a new 700-mppeak appears. The e.s.r. signal reappears when the catechol has been trans-formed to muconate by exposure to oxygen; a t the same time the 700-mppeak disappears.It would be of interest to know if both atoms of iron inthis pyrocatechase preparation are exchangeable during reaction, or alter-natively to know if the M . ureae preparation contains one or two atoms ofiron per enzyme molecule. It is clear that preparations of this enzyme fromdifferent bacteria, especially Pa. arvilh, N. ureae, Ps. JZuorescens, mdBrevibacterium ficscum are markedly different with respect to the effect ofFe2+ ions and reducing compounds upon activity and substrate specificity.It has been tacitly assumed in reactions involving the addition of twoatoms of oxygen to the carbon substrate that both atoms of oxygen arederived from the same molecule, and further that both atoms of oxygen donot become attached to the same carbon atom.With the availability ofhighly enriched 180 and " high-molecular-weight " mass spectrometers ithas been possible to test and verify this assumption. Thus, in an atmospherecontaining only the 180-180 and 160-160 species of oxygen, the dimethylester of the cis,cis-muconate formed during pyrocatechase-catalysed oxygena-tion of catechol had molecular masses of 170 and 174 only.112 Furthermore,the fragmentation pattern showed that only one atom of l 8 0 was incor-porated into each of the carboxyl groups of ci&s-muconate.llzCatechoE 2,3-oxygenase (metapyrocatechase). Catechol 2,3-oxygenase wascrystallized from Ps. arvilh after only a 30-fold purification of extracts.103,The molecular weight of 140,000 was calculated from sedimentations of thehomogeneous protein in the ultracentrifuge.Colorimetric analysis revealedone atom of iron per protein molecule and, unlike pyrocatechase, catechol2,3-oxygenase was colourless. E.s.r. spectral data indicate that the ironis in the Fe2* state. Native catechol2,3-oxygenase does not give a signal a tg 4.2, but this appears when catechol is also added to aerobic systems.15 Itseems unlikely that a ferric state arises only when reaction occurs or whenthe substrate (or analogue) can form a complex with the metal. Unlikepyrocatechase, catechol 2,3-oxygenase is easily resolved from its iron bylfl T. Kakazawa, Y. Kojima, IE. Fujisawa, 3X. Nmaki, and 0. Hayaishi, J . Biol.112 N. Itade, Biochtm. Biophys.Res. Comnz., 1965, 20, 149.Chenz., 1965, 240, PC3224462 BIOLOGICAL CHEMISTRYhydrogen peroxide oxidation and dialysis, and competitively inhibited byFe2+-chelating agents.l53,4-Dihydroxyphenylacetate 2,3-0xygenase. Pseu&nwnus ovalis, aftergrowth on p-hydroxyphenylacetate, yields extracts from which 3,4-dihy-droxyphenylacetate 2,3-oxygenase has been crystallized. '9 32,105 The crys-tals were colourless but showed a maximum absorption a t 280 mp and ashoulder at 292 mp. Ultracentrifugal analysis revealed a homogeneouspreparation with a molecular weight of 100,000; each molecule of enzymecontained four to five atoms of iron. It seems that the iron in these pre-parations is in the Fe2+ form, like catechol2,3-oxygenase, since it is inacti-vated by hydrogen peroxide and reactivated by Fe2+ ions.Tryptophctn oxygenase (tr yptophctn pywoktse).When L-tryptophan pyr-rolase preparations from Pseudomoms extracts are inactivated by ageing,addition of ascorbate or hzmatin (ferriprotoporphyrin IX) can restoreenzymic activity.15 Tryptophan itself, after prolonged incubation, will alsoreactivate this enzyme, especially under anaerobic ~onditions.1~~ The reacti-vation process is accompanied by changes in the absorption spectrum of theenzyme, suggesting that ascorbate and tryptophan reduce the iron to theFe2+ form; in fact the activity of the enzyme is directly related to its redoxstate. Spectral and redox changes that occur in tryptophan pyrrolase duringcatalysis show reduction of the Fe3+ form to the Fe2+ form, but this is notstoicheiometric initially.Anaerobic incubation of the pyrrolase with trypto-phan results in substrate-dependent reduction of enzyme-hzmatin to enzyme-haeme ; oxygen reoxidizes this, suggesting a cyclic oxidation-reduction of thehaematin during catalysis. The hzematin analogue, protoporphyrin IXinhibits oxygenase activity which can be restored by excess of hzmatin.Difference spectra of the reaction mixture suggest the occurrence of an inter-mediate complex, probably of enzyme, tryptophan, and oxygen.15 Theactive coenzyme forms of haematin and haeme, and their participation in thecatalysis, make this enzyme exceptional among oxygenases that catalyse theaddition of two atoms of oxygen to the carbon substrate.However, specula-tion concerning the mechanism of reaction must be reserved until the r61eof copper has been elucidated. Feigelson et ~ 1 . ~ ~ 3 have recently found largeamounts of bound copper in their purest pyrrolase preparations, and theactivity of the enzyme is inhibited by specific chelators for cuprous or cupricions; other chelating agents do not inhibit.The enzyme catalysing the formation ofcatechol from anthranilate has been obtained from Ps. a e r u q i n ~ s a , l ~ ~ ~ 115Ps. $uorescens 115 -117 and Micrococcus ureae .115 This complex reactionconsumes one mole each of oxygen and NADH, with formation of one moleAnthranilate hydroxylase.113 P. Feigelson, Biochim. Biophys. Acta, 1964, 92, 187; P. Feigelson, Y. Ishimura,and 0.Rayaishi, ibid., 1965, 96, 283; idem., Biochem. Biophys. Res. Comm., 1964, 14,96; H. Maeno snd P. Feigelson, Biochem. Biophys. Res. Comm., 1965, 21, 287.I1*T. Higashi and Y. Sakamoto, J . Bwchem. (Japan), 1960, 48, 147.115 A. Ichihara, K. Adachi, K. Hosokawa, and Y. Takeda, J . Biol. Chem., 1962,28'7, 2296.116 H. Taniuchi, M. Hatanaka, S. Kuno, 0. Hayakhi, M. Nakajima, N. Kurihara,J . Biol. Chem., 1964, 239, 2204.I1'S. Kobayashi, S. Kuno, N. Itada, and 0. Hayaishi, Biochem. Biqhys., Res.Comm., 1964, 16, 556RIBBONS : MICBOBIOLOGICAL DEGRADATION 463each of carbon dioxide and ammonia per mole of anthranilate used and cate-chol formed.ll6 It was suggested that intermediary formation of an epoxide,and its subsequent hydrolysis, occurred. However, Kobayashi et aL117showed that the four atoms of oxygen in cis&-muconate are all derivedfrom molecular oxygen and not fkom water.Consequently, it seems likelythat an epoxide is not formed, but that both atoms of an oxygen moleculeadd across carbon atoms 1 and 2 of anthranilate to yield a cyclic peroxide.The unusual requirement of Fe2+ ions for maximal hydroxylase activitylends further support to this hypothesis of addition of a single molecule ofoxygen to anthranilate; an experhen$ similar to that conducted by Itada 11%with pyrocatechase should verify this point.PhenyZatanine hydroxylase. Kaufnirtn lls has studied this enzyme frommammalian sources in some detail but only recently has a similar enzymebeen extracted from Pseudomoms sp.Guroff and Ito 119, 120 have demon-strated a requirement for Fez+ ions, tetrahydropteridine and molecularoxygen for tyrosine formation with purified extracts. Preincubation withFe2+ is usually necessary for full activity. The involvement of pteridine inthis reaction parallels the mammalian enzyme; however, there are somedifferences in the specificity of response to pteridine analogues. The incor-poration of ISO, into the tyrosine formed has been shown with whole cells ofPs. aeruginosa.121Salicytate hydroxylase. During purification of a salicylate hydroxyla,sefrom cells of a Gram-positive coccus, a requirement for flavin adeninedinucleotide (FAD) was demonstrated.151122 Catalytic quantities of FADare required if a source of NADH, or NADPH, is available.The stoicheio-metry of the reaction corresponds to:FADSalicylafe + NADH, + 0, --+ Catechol + NAD + H,O + COa2,3-Dihydroxybenzoate, phenol, benzoate, and anthranilate are not meta-bolized by this system, and the introduction of the second hydroxyl isassumed to replace the carboxyl group. Inhibition of the enzyme by metalchelators can be reversed by dialysis ; metal-ion additions were withouteffect.Several other microbial aromatic oxygenases havebeen described but not in sufficient detail to discuss possible mechanisms.Those that have not been referred to previously include benzoate hydroxyl1ase,117 kynurenic oxygenase, naphthalene hydroxylase,4* protocatechuate3,4-oxygenase,123 protocatechuate 4,5-oxygenase,% l 4 gentisate oxyge-n a ~ e , l ~ ~ , 125 7,8-dihydroxykynurenate oxygena~e,~~ 5-(p-carboxyethyl)-4,6-11* S.Kaufman, ‘‘ Oxygenases,” ed. 0. Hayaishi, Academia Press, Xew York andLondon, 1962, p. 129.lZo G. Guroff and 1. Ito, J . BWE. Chem., 1965, 240, 1175.121 K. Takashima, D. Fujimoto, and N. Tamiya, J . Biochem. (Jupun), 1964, 55,12* M. Katagiri, S. Yamamoto, and 0. Hayaishi, J . Biol. Ohern., 1962, 237, PC2413.123R. Y. Stmier rand J. L. Ingraham, J . Biol. Chem., 1954, 210, 799.1 2 4 S . Sugiyams, K. Yano, H. Tanaka, K. Komagata, and K. Arims, J . Cen. AppE.126 L. Lmk, Biochim. Biophys. Acta, 1959, 34, 117.0 t h - oxygenases.C. Guroff arid T. Ito, Biochim. Biophya. Acta, 1963, 77, 159.122.Microbiot?. (Japan), 1958, 4, 223464 BIOLOGICAL CHEMISTRYdihydroxypicolinate oxygena~e,~~ and homogentisate oxygenase,126 ex-cluding other heterocyclic oxygenases.Regulation of metabolism.-Regulation of the synthesis of the enzymeswhich catalyse the catabolism of aromatic compounds has only recentlybeen studied.It is known that these enzymes are generally elaborated inresponse to specific substrates and the process was thought to be sequen-tia1,12' e.g., substrate A induced enzyme a for its metabolism to compound B,which in turn acted as inducer for the synthesis of enzyme b for its ownmetabolism to compound C, and so on. Sequential induction undoubtedlyregulate the synthesis of some enzyme sequences, but it is supplemented byco-ordinate induction, whereby a group of enzymes is synthesized in re-sponse to a single inducer.Co-ordinate induction of a group of enzymes ispresumably controlled by a single operon or regulon.12SRegulation of the aromatic pathway of tryptophan metabolism. The aro-matic pathway of tryptophan oxidation by Ps. Jluorescens proceeds throughcatechol as shown in Scheme 6. The formation of the whole sequence ofenzymes involved is initiated by exposure of cells to L-tryptophan or L-kyn~renine.~~ Palleroni and Stanier 2 9 showed that L-tryptophan itselfdoes not act as an inducer; low but measurable quantities of tryptophanoxygeiiase (tryptophan pyrrolase) and formylkynurenine formamidase arepresent in uninduced cells and these enzymes form L-kynurenine, thereal inducer, which then induces co-ordinately and sequentially the forma-tion of all the enzymes of this pathway.The sequential nature of the induc-tion of enzymes by kynurenine and anthranilate was demonstrated by atechnique that might be exploited further. Cells were exposed to L-trypto-phan for a period sufficient to induce only the enzymes for its own catabolismto ant,hranilate. Ultraviolet irradiation of the suspension to prevent furtherprotein synthesis and incubation with more tryptophan resulted in an almostquaiititative conversion into anthranilate. Anthranilate serves as inducerfor enzymes catalysing reactions succeeding but not those preceding itselfin the sequence; other sequential steps are probably involved.Theenzymes employed for DL-mandelate oxidation by Ps. putida were alsoshown to be induced co-ordinately and sequentially.l6.12'3 129 The first fiveenzymes 130-132 (the " mandelate " group), mandelic racemase (El), L-mandelic dehydrogenase (E2), benzoylformic carboxylase (EJ, and benz-aldehyde dehydrogenases (E4J and (ESb), appear to be controlled by asingle operon 128 and are co-ordinately induced by either DL-mandelate orbenzoylformate, and also by the gratuitous inducer phenoxyacetic acid(Scheme 7). Benzoate does induce formation of these enzymes, but onlythose lower in the metabolic sequence, and is the first sequential inducer inRegulution of the synthesis of enzymes of the mandelate pathway.12u P. J. Chapman and S. Dagley, J . Gen. Microbiol., 1962, 28, 251.12' R. Y. Stanier, J. Bacteriol., 1947, 54, 339.lP8 F. Jacob and J.Monod, J . Mol. Biol., 1961, 3, 318; W. K. Maas and E. McFall,Ann. Rev. Mhrobiol., 1964, 18, 96.12* I. L. Stevenson and J. Mandelstam, Biochem. J., 1965, 96, 354.130 I. C. Guwlus, C. F. Gunsalus, and R. Y. Stanier, J . Bacterwl., 1953, 68, 538.131 R. Y . Stanier, I. C. Gunsalus, and C. F. Gunsalus, J. Bucteriol., 1953, 66, 543.132 C. F. Gunsalus, R. Y . Stanier, and I. C. Gunsalus, J . Racteriol., 1953, 66, 548RIBBONS : MICROBIOLOGICAL DEGRADATION 465this pathway. It was not determined unequivocally if a second sequentialstep occurs for the induction of the catechol oxygenase or succeedingenzymes, but this seems likely. Similarly, the protocatechuate group ofenzymes (Scheme 7 ) may not all be induced co-ordinately; one or moresequential steps may be involved.Numerous gratuitous aromatic inducers cause complete derepression(induction) of the enzymes of the mandelate group in some mutants that areconstitutive for enzymes of this group, i.e., formed in the absence of exo-genous inducer.The catechol group of enzymes is unaffected. When theinducer is also a substrate then maximal synthesis of enzymes of the catecholgroup also occurs. Vanillic acid is a gratuitous inducer for the group ofenzymes converting protocatechuate to 3-oxoadipate in 1N. crassa l8 (Scheme1); it seems likely that this group of fungal enzymes is also formed co-ordina t el y.It is clear that an induction mechanism for the synthesis of enzymes oran enzymic sequence would not control the quantity of enzymic activityrequired. Additional methods of regulation are required for this, and specificmetabolic repressions of inducible enzymes have been amply demonstratedby Mandelstam.Thus, pyruvate, a product of the reaction catalysed bytryptophanase in Escherichia coli, specifically represses the formation of thistryptophan-inducible enzyme.133Specific end-product repression is also a regulating mechanism for thesynthesis of the sequence of enzymes that catalyse mandelate and p-hydroxy-mandelate oxidation. The first five enzymes of the mandelate group(Scheme 7) are subject to end-product repression by succinate and acetate.However, several of the intermediates of mandelate (and p-hydroxymande-late) oxidation are able to repress the enzymes of this group and other enzymesof the sequence that catalyse their formation; these are the products of eachsequential step of the pathway, i.e., catechol (or protocatechuate) and ben-zoate (or p-hydroxybenzoate).Succinate and acetate are also able to repressthe formation of enzymes of the catechol (or protocatechuate) group and ben-zoate (or p-hydroxybenzoate) hydroxylase. The resultant control mechan-ism is thus called multi-sensitive end-product repression 129, 134 (Scheme 7).Benzaldehyde and p-hydroxybenzaldehyde were also tested as possiblerepressors and were found to repress almost completely the synthesis of theenzymes of the mandelate group. However, the ability of these cells to growon p-hydroxybenzaldehyde was not impaired. A third non-specific benzal-dehyde dehydrogenase is induced under these conditions and this is notcontrolled by the same operon as the mandelate group.The ability of thehenzaldehydes to repress the formation of the enzymes of which they aresubstrates is almost analogous to the ability of kynurenine to induce thesynthesis of the enzyme of which it is the product.Induction and repression of the mandelate group of enzymes is the resultof a balance of inducer and repressor, in that end-product repression may bereversed by higher concentrations of the inducer.129~134The recent renewed interest in the metabolism of and the effect of133 E. McFall and J. Mandelstam, Nature, 1963, 197, 880.lS4 J. Mandelstam and G. A. Jacoby, Biockem. J., 1965, 94, 569CHOH*COZH QPRO1GBenzoatehydroxylasep-Hydroxybenzoate (OH)(5 7) (58) hydroxylasRIBBONS : MICROBIOLO~ICAL DEGRADATION 467halogenated benzoates on the enzymes degrading benzoate should yieldfurther information about the control mechanisms of the synthesis of in-ducible enzymes.135Non-speci$c multi-enzyme systems.The earlier suggestiom 131, u6 thatp-hydroxymandelate and mandelate are oxidized by the same sequence ofenzymes has been conhrmed.129 The mandelate group of enzymes catabolizeboth substrates to yield either benzoate and p-hydroxybenzoate and thesethen induce specifically enzymes for their own degradation (Scheme 7).A similar non-specific oxidation sequence appears to operate in Ps.aerugilzosa T1 when o-, m-, or p-cresol or phenol are the substrates of meta-bolism.1° These cells do not distinguish between these four carbon sourcesas inducers nor as substrates.All induce a sequence of enzymes which w i l lmetabolize them, wia catechol (from phenol) or a methylcatechol (from thecresols), according to Scheme 2. This situation may extend to other ba~teria.~It has been suggested 41 that catechol 2,3-oxygenase specificity alsoextends to the polynuclear substrates of ring fission (Scheme 5). In viewof the homology of several of the enzymic steps that occur during the meta-bolism of polynuclear compounds and of some catechols, it is tempting tosuggest that other common enzymes mediate these reactions.The ability of a variety of substrate-inducers to initiate the synthesis of amulti-enzyme sequence that can metabolize several compounds eventuallyto common metabolites represents a great economy to the cell.As a conse-quence of such low specificities, the cell is not required to carry and replicate‘‘ extra ” genetic information as DNA for each reaction sequence. When thecell is presented with more than one of these non-specific substrate-inducers,the synthesis of a single multi-enzyme system to deal with all of them is asaving on both protein and RNA synthesis. The example, par excellence, isthe metabolism of certain bicyclic terpenoids by a non-specific multi-enzyme system.l37I n contrast, it has also been demonstrated that some bacteria? e.g.,Vibrio 0/1, are able to synthesize either catechol 172-oxygenase or catechol2,3-oxygenase depending on the nature of the primary inducer.13* Itappears that the more non-polar substrate inducers, e.g., the cresols ornaphthalene, lead to catechol2,3-oxygenase synthesis, whilst polar substrate-inducers, e.g., benzoate, yield the 1,2-0xygenase.~~ 138 However, this is notso in every case.lO? 104In the review by Evans and in these Reports attention has been devotedmainly to bacterial metabolism of aromatic compounds.It is clear thatmost groups of micro-organisms are able to catabolize these compounds.Fungal metabolism of some aromatic compounds has been reviewed re-~ent1y.l~~ Many yeasts are also able to grow on simple phenolic compounds ;I4*ls6 F. Bernheim, J . Biol. Chem., 1953, 203, 775; D. E. Hughes, Biochem. J . , 1965,96, 181; A.G. Callely and J. G. Jones, Biochem. J., 1965, 97, 11C.136 S. E. Gunter, J . Bacterial., 1953, 66, 341.la’ I. C. Gunsalus, P. J. Chapman, and J. F. Kuo, Biochem. Bwphys. Res. Comm.,1965, 18, 924.13* E. GrifEths, D. Rodriques, J. I. Davies, and W. C. Evans, Biochem. J., 1964,91, 16P.13# M. E. K. Henderson, Pure Appl. Chew., 1963, 7 , 589.140 G. Harris and R. W. Ricketts, Nature, 1962, 195, 473468 BIOLOGICAL CHEMISTRYthis is an area where there is only a sparse knowledge of the metabolicroutes involved.25$ 141 It seems likely that algae and protozoa will alsoyield enzymes that degrade benzenoid compounds; in this respect somephotosynthetic bacteria have no difficulty in photometabolizing aromaticcompound~.~4~9 l43Recent work describing the biosynthesis of aromatic cornpo~nds,~~Pthe catabolism of heterocyclic compounds such as nicotine,145 and the vita-mins pyridoxine,146 nicotinic acid,l4’ and riboflavin,l48 and structures such asflavonoids lP9 is readily available.A review on the microbiological oxidationof pesticides has also appeared.lS0141 J. S. Hough and D. A. J. Wase, J . gen. ITlicrobiol., 1965, 39, v.148 M. H. Procter and S. Scher, Biochem. J., 1960, 76, 33P.148 E. R. Leadbetter and A. Hawk, Bact. Proc., 1965, 22.146 R. L. Gherna, S. H. Richardson, and S. C. Rittenberg, J . Biol. Chem., 1965,lJ6 E. E. Snell, A. A. Smucker, E. Ringlemann, and F. Lynen, Biochem. Z., 1964,E. J. Behnnan and R. Y. Stanier, J . Biol. Chem., 1957, 228, 923.14*D. R. Harkness y d E.R. Stadtman, J . Biol. Chem., 1965, 240, 4089.lQS G. H. N. Towers, Biochemistry of Phenolic Compounds,” ed. J. B. Harborne,15* R. W. Okey and R. H. Bogan, J . Water Pollution Control Fed., 1965, 37, 692.B. A. Bohm, Chena. Rev., 1965, 65, 435.240, 3669.341, 109.Academic Press, London and New York, 19644. CARBOHYDRATE SULPHATESBy D. A. Bees(Chemktrg Department, The University, West Mains Road, Edinburgh 9)THE sulphate half-esters of carbohydrates have never before been the soletopic for a Report in this Series, and it is 16 years since the last comprehen-sive Review in any journal.1 Some individual aspects have, however, beencovered separately from time to time, and reference will be made later tothe more recent of such Reviews. The enzymic hydrolysis of carbohydratesulphates will not be discussed; this has been adequately reviewed else-where.2,General.-Carbohydrate sulphates occur naturally in animal tissues andin marine algae.True carbohydrate sulphates would appear to be rare inhigher plants; the “plant sulpholipid” which is so widespread, is not asulphate ester but a sulphonic acid. Carbohydrate sulphates rarely, if ever,play such an active part in metabolism as do many carbohydrate phosphates.Their biological functions in cell walls, membranes, intercellular regions,and other situations, would appear to be connected with their physicalproperties more usually than with their chemical reactions. The presenceof ionised sulphate groups, and often of consequent polyelectrolyte character,must greatly influence physical properties.It is a striking coincidence thatmany different polysaccharide sulphates appear to contain two differentsugar units in a strictly alternating linear structure-an arrangement that israre in other polysaccharides. There may be some relation between thecharge of the sulphate and the sizes of the sdphate group and disaccharideunit which leads to conformations and interactions that are biologicallydesirable. It is important that the detailed molecular structures be deter-mined so that their full biological significance can be understood.Prom a chemical point of view, structure determination, especially ofhigh-molecular-weight carbohydrate sulphates, presents a number of inter-esting problems and opportunities.Sulphate groups can normally beretained during methylation of the hydroxyl groups, and information abouttheir location can therefore be obtained by subsequent hydrolysis. Theinformation is, however, ambiguous, and additional evidence is required todistinguish between the site of the sulphate and of glycosidic substitution.This may be obtained by methylation of the desulphated polysaccharide,4periodate oxidation before and after de~ulphation,~ alkaline eliminati~n,~a~ g s 7E. G. V . Percival, Quart. Rev., 1949, 3, 369.K. S. Dodgson and B. Spencer, Ann. Reports, 1956, 53, 318.J. R. Turvey, Adv. Carbohydrate Chem., 1965, 20, 183. ’ (a) R. W. Jeanloz and P. J. Stoffyn, Fed. R o c . , 1958, 17, 249; R. W. Jeanloz,P.J. Stoffyn, and M. TrBmGge, ibid., 1957, 16, 201; (b) S. Hirano, P. Hoffman, and K.Meyer, J. Org. Chem., 1961, 26, 5064; (c) T. C. S. Dolan and D. A. Rees, J. Chem. Soc.,1966,& 3534.(a) J. P. McKinnell and E. Percival, J . Chem. SOC., 1962, 3141; ( b ) E. Percivaland J. K. Wold, ibid., 1963, 5459.eD. A. Rees, J . Chem. SOC., 1961, 5168.7D. A. Rees, J . Chem. Soc., 1963, 1821470 B I0 L 0 G I C 9 L CHEMISTRYinfrared spectroscopy, 7, isolation of sugar sulphates after partial fragmenta-tion,’, and measurement of the rate of hydrolysis of the sulphate ester.’? 10Aqueous acid hydrolysis of sulphate esters occurs a t about the same rate asglycosidic hydrolysis, and a complicated mixture of products is therefore tobe expected in structure analysis of polysaccharide sulphates by straight -forward partial acid hydrolysis.Mild treatment with rnethanolic hydrogenchloride (a heterogeneous reaction) effects desulphation of many poly-saccharides without substantial glycosidic cleavage.ll This method isnormally applied in conjunction with methylation or periodate oxidation(see above). Less frequently used methods are acetylative desulphation 12and reductive removal of the mixed ester which can be prepared with diazo-methane.13 A simplification of the partial hydrolysis products is achieved bythe use of rnercaptolysis ** or acetolysis,15 because desuIphation oecurs muchfaster than the rate of depolymerisation under both these conditions.There are additional problems in the structure determination of carbo-hydrate sulphates from animal tissues, owing to their covalent combinationwith protein or lipid.The investigation of the linkages between glycosamino-glycan sulphates and protein is a t a particularly interesting and excitingstage, and a full report of recent work is given later. Sulphated-carbo-hydrate-protein complexes of other types have also been isolated fromanimal tissues, but these are less well characterised at present.The biosynthesis of carbohydrate sulphates would appear to be similarto other sulphate esters, the transfer of stdphate being from adenosine 3’-phosphate 5‘-sulphatophosphate (PAPS) .16 An improved synthesis ofthe analogue, adenosine 5’sulphatophosphate, involves the reaction of the1 -ethoxyvinyl derivative of barium 2-cyanoethyl sulphate with adenylicacid, and then removal of the protecting gr0ups.l’Methods.-The fmal volume of the “Methods in CarbohydrateChemistry ” series includes some sections on carbohydrate sulphates.lsBecause of the importance in medicine of polysaccharide sulphates fromanimal tissues, their identification and analysis have been much discussed.Methods have been described for detection and determination of polysac-charide sulphates in animal tissues and extracts,lg, 20 for their separation8 A.G. Lloyd, K. S. Dodgson, R. B. Price, and F. A. Rose, Bwchim. Biophys.Acta, 1961, 46, 108; A. G. Lloyd and K. S. Dodgson, ibid., p. 116.9 S . Suzuki and J. L. Strominger, J . Bid. Chem., 1960, 235, 2768; S. Suzuki,ibid., p.3580; J. R. Turvey and D. A. Rees, Nature, 1961, 189, 831.10 D. A. Rees, Biochem. J., 1963, 88, 343.11 R. Johnstone and E. G. V. Percival, J . Chem. Soc., 1950, 1994; T. G. Kantorand M. Schubert, J . Amer. Chern. SOC., 1987, 79, 152.12 M. L. Wolfrom and R. Montgomery, J . Amer. Claena. SOC., 1950, 72, 2859; T.Dillon and P. O’Colla, Proc. Roy. Irish Acad., 1951, 54, B, 51.13 G. Coleman, M. Higgs, A. Holt, and M. B%ulvin, Chewa. and Ind., 1963, 376.l4 A. N. O’Neill, J . Amer. Chem. Soc., 1955, ‘77, 6324.15K. Morgan and A. N. O’Neill, Cunad. J . Chem., 1959, 37, 1201.16 P. W. Robbins in “ The E n ~ p e s , ” eds. P. D. Boyer, H. Lardy, and K. Myrbiick,17 G. R. Banks and D. Cohen, J . Chem. Soc., 1965, 6209.18 “ Methods in Carbohydrate Chemistry,” vol.V, ed. R. L. Whistlsr, Academia19 S. A. Barker, C. N. D. Cruickshank, and T. Webb, Carbohydrate Em., 1965,80 M. Schmidt and A. Dmochowske, Bwchm. Biophys. Acta, 1964, 83, 137; C. A.Academic Press, New York, 1962, vol. 6, p. 383.Press, New York, 1965.1, 52REES : CARBOHYDEATE SULPHATES 47 1and detection by electrophoresis,21 and for the determination of their com-ponent sugars by enzymic,L2 colorimetric,23 and automatic colorimetric 24methods, and by gas ~hromatography.~5 Problems inherent in the deter-mination of hexosamines after hydrolysis in the presence of protein havebeen studied.26 There have been further refinements in Yaphe’s convenientmethod for the colorimetric determination of 3,6-anhydrogalactose in algalpolysaccharide sulphates.2’ This sugar can also be determined by polaro-graphy.28 The sulphur in polysaccharides can be determined by neutronactivation analysis.29The histochemistry of glycosaminoglycans has been re~iewcd.~O Methodsfor distinguishing different polysaccharide sulphates in tissue sections 31include selective suppression, using electrolytes, of their interaction withAlcian Blue dye,32 and microfractionation 33 and specific enzymolysis 34 inconjunction with histochemical studies. Glycosaminoglycan sulphates canbe stained for electron microscopy by the use of a colloidal iron reagent.35PolysacchaPide Sulphates born Animd Tissues.-These usually occur ascarbohydrateprotein macromolecules. A later section covers the carbo-hydrate-protein linkages ; the structure and metabolism of the carbohydratepart is discussed here.These are the best known and character-ised polysaccharide sulphates from animal tissues.The work of the pastdecade which has led to the determination of the main structural features ofthe polysaccharide chains, has been reviewed by M ~ i r , 3 ~ and by Brimacombeand Webber in their remarkably up-to-date b00k.~7 The overall picture issummarised in Table 1. Unfortunately, the nomenclature is not a t allClycosaminoglycan sulphates.Antonopoulos, S. Gardell, J. A. Szirmai, and E. R. de Tyssonslr, ibid., p. 1; D. S. Trundleand G. V. Mann, ibid., 1965, 101, 127; K. E. Kuettner and A. Lindenbaum, ibid.,p. 223; R. G. Brown, G. M. Button, and J. T. Smith, Analyt. Biochem., 1965, 12, 195;G.Manley, Nature, 1965, 206, 1253; J. S. Mayes and R. G. Hansen, Analyt. Biochem.,1965, 10, 15.21 J. H. Brookhart, J . Chromatog., 1965, 20, 191; S. Magnusson, Arlciv Kemi, 1965,24, 211; A. M. Saunders and S. Thomsen, Nature, 1965, 205,497; L. B. Jacques, R. E.Ballieux, and C. van Arkel, Fed. PTOC., 1964, 23, 459; S. Okhuma, T. Shinohara, andC. Miyauchi, Nature, 1965, 207, 527.23 0. Luderitz, D. A. R. Simmons, 0. Westphal, and J. L. Strominger, Analyt.Biochem., 1964, 9, 263; J. M. Sempere, C. Gancedo, and S. Asensio, ibid., 1965, 12,509.23 T. A. Good and S. P. Bessman, AnaZgt. Biochem., 1964, 9, 253.24 E. A. Balazs, K. 0. Bernsten, J. Karossa, and D. A. Swann, AnaZyt. Biochem.,25 M. B. Perry, Canad. J . Biochem., 1064, 42, 451.26 E.F. Hartree, Analyt. Biochem., 1964, 7, 103.27 W. Yaphe and G. P. Arsenault, Analyt. Biochem., 1965, 13, 143.28 T. Fujiwara, K. Morihara, and C. Araki, Bull. Chem. SOC. Japan, 1964, 37, 760.29 E. L. McCandless, AnaZyt. Biochem., 1964, 7, 357.30 R. C. Curran, Internat. Rev. Cytology, 1964, 17, 149.31 T. Sugiyama, Acta Path. Japon., 1964, 14, 413.32 J. E. Scott, J. Dorling, and C. Quintarelli, Biochem. J., 1964, 91, 4P.3 3 J. A. Szirmai, Biochem.. J . , 1964, 90, 1P.34 T. J. Leppi and P. J. Stoward, J . Histochem. Cytochem., 1965, 13, 406.35 R. C. Curran and A. E. Clark, Bwchem. J., 1964, 90, 2P; R. C. Curran, A. E.36 H. Muir, Internat. Rev. Connectizqe Tissue Res., 1964, 2, 101.37 J. S. Brimacornbe and J. M. Webber, “ Mucopolysaccharides,” Elsevier,1965, 12, 547, 559; D.A. Swann and E. A. Balazs, ibid., p. 565.Clark, and D. Lovell, J. Anat., 1965, 99, 427.Amsterdam, 1964TABLE 1 i i a i n structural features of glycosaminoglgcanRepeating unitChondroitin 4-sulphateChondroitin 6 -sulphateDematan sulphateKeratan sulphateHeparinHeparan sulphate( 1-t 4) -0 - P-D- (glucopyranosyluronic acid) -( 1+ 3) -2-acetamido-2 -deoxygalactopyranosyl 4-sulphate( 1 --t 4) -0 - P-D - (glucopyranosyluronic acid) - ( 1 --+ 3) -2 -acetamid0 -2 -deoxy(galactopyranosyl 6-aulphate)(1+4)-0- a-~-(idopyranosyluronic acid)-( l+ 3)-2-acetamido-2-deoxy-galactopyranosyl 4-aulphate( 1 4 4) -2 -acetamido-2 -deoxy -0- / l - ~ - (glucopyranosyl 6 -sulphate) -( 1 --f 3)galactop yranos y 1( 1 --f 4) -0 - a-D - (glucopyranosyluronic acid 2 -8ulphate) - ( 1 + 4) - 2 -deoxy-2-amino-0-a-D-glucopyranosyl 6-sulphateSulphated polymer of glucosamine and gliicuronic acid with a structurehas features in common with heparin.It differs in degree of sulphation,that some glucosamine units are N-acetylated, and perhaps also inrespects.~ o t e . These structures are idealised. Different preparations may not always be sulphated as fully or ar, regularlyIn most eases it has yet to be definitely of sugar units near the linkage to protein in all cases SO far examined.featuresREES : CARBOHYDRATE SULPHATES 473s tandardised. Jeanloz's suggestions 38 will be followed here, and the readeris referred to his article 38 for a useful '' Dictionary " which might help inrelating this Report to other literature.The essentially 1 4 linked structure of heparin, which was shown bypartial hydrolysis of the carboxyl-reduced desulphated polysa~charide,~~ andby methylation of heparin 40 and its carboxyl-reduced N-acetylated desul-phated derivative,41 has been further confirmed by partial hydrolysis of3'-acetylated desulphated he~arin.4~ It seems that earlier 43 indicationsof 1+6 linkages might have been reversion artefacts.Synthetic 0-cc-D-glucopyranosyl-( 1+4)-2-amino-2-deoxy- cc-r>-glucose is identical with aproduct from carboxyl-reduced desulphated heparin, in confirmation ofthe a - 1 4 linkage between the glucuronic acid and glucosamine units inhe~arin.~4 The heparins from dog, beef, hog, sheep, and human tissues arebiologically, chemically, and physically similar ;45 analytical variations mightbe due to variable proportions of non-covalently bound sulphate 46 and otherimpurities. Glucosamine units in which the amino-groups are sulphated orunsubstituted, are converted into 2,5--anhydromannose by nitrous aciddeamination, with cleavage of the adjauent glycosidic link.Under carefullycontrolled conditions, only N-sulphated units react .47 This has been usedt o show that heparan sulphate from the livers of patients with the Hurlersyndrome (see p. 478) is heterogeneous with respect to N-sulphate content .48A polysaccharide of the heparin-heparsn sulphate type has been isolatedfrom whale organs. It contains a proportion of N-acetylated glucosamineunits, which would appear from the nature of the deamination products tooccur together in A crude heparinase from a Flaaobacterium hasbeen fractionated into a glucuronidase and an eliminase.The latter enzymecleaves heparin and heparan sulphate (but not desulphated heparin) in themanner that is now well known for many other uronic-acid containingpolysaccharides, with the formation of oligosaccharides with 4,5-unsaturateduronic acid end-gro~ps.~~ Comparison of the products from the eliminaseaction on heparin and heparan sulphate confirms that these polysaccharidesare to some extent structurally similar and promises to show whether thereare any differences other than in the pattern of sulphation and N-acetylation.38 R. W. Jeanloz, Arthritis and Rhewnatisnz, 1960, 3, 233.39 M.L. Wolfrom, J. R. Vercellotti, and D. Horton, J . Org. Chem., 1964, 29, 540,4 0 0. NominB, R. Rucourt, and D. Bertin, Bull. SOC. chim. France, 1961, 561.41 I. Danishefsky, H. B. Eiber, and A. H. Williams, J. Biol. Chem., 1963, 238,2895; RI. L. Wolfrom, J. R. Yercellotti, and D. Horton, J . Org. Chem., 1964, 29, 547.4 2 I. Danishefsky and H. Steiner, Biochem. Biophys. Acta. 1965, 101, 37.4 3 I. Danishefsky, H. B. Eiber, and E. Langholtz, Biocheni. Biophys. Bes. Coinin.,1960, 3, 571; J. A. Cifonelli and A. Dorfman, ibid., 1961, 4, 328.41 M. L. Wolfrom, H. El Khadem, and J. R. Vercellotti, J . Org. Chem., 1961, 29,3284.4 5 G. H. Barlow, L. J. Coen, and M. M. Mozen, Biochem. Biophys. Acta, 1964,46 J. R. Helbert and M.A. Marini, Biochim. Biophys. Acta, 1964, 83, 122.4 7 J. A. Cifonelli, Fed. Proc., 1965, 24, 354; compare D. Lagunoff and G . Warren,Arch. Biochem. B i o p h y ~ . , 1962, 99, 396; A. B. Foster, E. F. Martlew, and M. Stacey,Chem. and Id., 1953, 825.48 J. Knecht and A. Dorfman, Biochem. Biophys. Res. Comm., 1965, 21, 509.4 9 Z . Yosozawa, Biochein. Biophys. Res. Comm., 1964, 16, 336.so A. Linker and P. Hovingh, J . Biol. Chem., 1965, 240, 3724.Qand earlier Papers.83, 272474 BI 0 LO GI C AL CHEMI S TRYKeratan sulphate from bovine cornea can be separated on the basis ofethanol solubility into two sub-fractions 51 which differ, as do various samplesof corneal keratan ~ u l p h a t e , ~ ~ in the ratio of sulphate to hexosamine and insome physical propertiea.Keratan sulphates from skeletal tissues alsoshow variations.52, 53 There are, however, more profound differences be-tween the preparations from the different types of tissue, particularly in theassociated peptide and in a t least some of the carbohydrate-peptide linkages,but also in other respects.52, 53 It is still an open question whether thereare fundamental differences in the molecular structures of the polysaccharidechains. The accepted structure for keratan sulphate (Table 1) was estab-lished using a preparation from Significant amounts of galactos-amine appear to be combined in skeletal keratan sulphates, in a form that isnoti removed by fractionation or treatment with hyaluronidase and that isnot associated with a molar equivalent of glucuronic acid.This has ledto the suggestion that galactosamine is a molecular component of skeletallreratan sulphate . 52There have been few developments in the understanding of biosynthesisof the golysaccharide chains since the full account of this topic last year.=The possible biosynthetic intermediates chondrosine 1 -phosphate and uridinediphosphate chondrosine have been synthesised.55 A compound that appearsto be a sulphated cytidine monophosphate has been isolated from rat skinand might be involved in polysaccharide sulphate bios~nthesis.~6 Dermatansulphate has a less broad molecular-weight distribution than would beexpected if it were synthesised by random p~lymerisation.~~ Glucosaminecan be utilised locally for glycosaminoglycan synthesis a t the sites of con-nective-tissue formation in rats.5s Recent work on the enzymic degradationof glycosaminoglycans suggests that many of the degradative enzymes inanimal cells might be located in lysosomes.5* These cytoplasmic bodiesappear to contain many other hydrolytic enzymes that are presumablyinvolved in intracellular digestion.GOSome information about polysaccharide sulphate conformations has beenobtained by physical methods.An X-ray study of oriented films of a sub-fraction of chondroitin 4-sulphate containing only one sulphate for everythree disaccharide units, suggests that the sulphate distribution is regularand that the polysaccharide chain is more flexible than in hyaluronic acidbecause the repeating period is shorter.61 The similarity in optical rotatory6 1 B. Wortman, Biochem.Biophys. Acta, 1964, 83, 288.5% M. B. Mathews and J. A. Cifonelli, J . BioZ. Chem., 1968, 240, 4140.53 N. %no, K. Meyer, B. Anderson, and P. Hoffman, J. BioZ. Chem., 1966,240,1005.54 P. T. Grant and J. L. Simkin, Ann. Reports, 1964, 61, 491.6 5 A. H. Olsvesen and E. A. Davidson, J. BioZ. Chem., 1966, 240, 992.58 S. A. Barker, C. N. D. Cruickshank, and T. Webb, Carbohydrate Bee., 1965,1, 62.57 C. Tanford, E. Marler, E. Jury, and E. A. Davidson, J . BbE. Chem., 1964, 239,4034.68 B. N. White, M. R. Shetlar, H. M. Shurley, and J. A. Schilling, Bhchem. Biophys.Acta, 1965, 101, 97.6 8 N. A. Aronson and E. A. Davidson, J . BWZ. Chem., 1965,240, PC3222; F.Eutterer,Fed. Proc., 1965, 24, 557; D. Fisher, P. W. Kent, and P. Pritchard, Biochem. J., 1966,98, 46P.6 O C. de Duve, Fed. Proc., 1964, 23, 1045.@IF. A. Bettelheim, Biochim. Biophys. Ado, 1964, 83, 350REES : CARBOHYDRATB SULPRATES 475dispersion curves between certain dermatan sulphate and chondroitinsulphate derivatives, is interpreted to mean that the L-iduronic acid Unitin dermatan sulphate exists in the Reeves C-l conformation, with thecarboxyl group axial.62 The absorption characteristics of the metachromaticcomplexes formed by Toluidine Blue with hyaluronio acid and with chon-droitin 6-sulphate suggest that the polysaccharide molecules have rigidc o ~ o ~ a t i o ~ in the complexes, in which the carboxyl groups are closetogether .63 Interactions between ~ e i g h b o ~ ~ g dye molecules bound toheparin give rise to optical rotation, similar to the effects known for poly-peptides and polynucleotides.6~Only brief mention is possible of recently published work on the naturaloccurrence and distribution of glycosaminoglycan sulphates.A dis-cussion of the r6le of mast cells in storing, synthesising, and dischargingheparin into the circulation, is contained in a recent book.G5 Non-sulphatedchondroitin has been isolated from squid skin.6s The glycosaminoglycansulphates from the following sources have been inyestigated : urine,"?fracture callus,68 rat E d n e ~ s , ~ ~ rat skin,f9 aortic tissue of the aortasof swine raised on a copper-deficient diet," cattle retina,72 sclera from bovineeyes,73 tadpole tail fin and back skin,'* human heart valves,T5 human um-bilical human teeth,77 human fetal ~kin,7~ and avian oviduct,egg, skin, and comb.79Other carbohydrate sulphates from aninacrE tissues, A rare example of anaturally occurring sdphate of a reducing oligosaccharide, is the trisacchar-ide derivative present in water extracts of lactating-rat mammary glands.It has been assigned the structure O-or-~-acet~~euraminyl-(2-+3)-0-B-~-(galactopyranosyl tj-sulphate)-( 1 -+4)-~-glucose, on the basis of its hydrolysisby neuraminidase, the resistance of the galactose unit to periodate oxidation,and the identification of lactose and galactose 6-sulphate as partial hydrolysisproducts. so The desulphated derivative occurs in urine.The relateddisaccharide sulphate, O-/~-D-( ga~actop~ano~yl 6-sulphate)-( 1 +t)-D-g~UCOSe,62 E.A. Davidson, Biochim. Biophys. Acta, 1965, 101, 121.esM. D. Schoenberg and R. D. Moore, Biochim. Bwphgs. Ada, 1964, 88, 42.8 p A. L. Stone, Fed. Proc., 1964, 23, 282.65 H. Selye, " The Mast Cells," Butterworths, Washington, 1965.K. Anno, Y. Kawai, and N. Seno, BiOChim. Bivphgs. Acta, 1964, 83, 348.67 6, S. Berenson and E. R. Dalferes, Biochim. Biophgs. Actu, 1965, 101, 183.8s C. A. Antonopoulos, B. Engfeldt, S. Gaxdell, S . - 0 . Eljertquist, rmd K. Solheirn,6s D. Allalouf, A. Ber, and N. Sharon, Biochim. Biophys. Acta, 1964, 83, 278.7o 0, V. Sirek, 8. Schiller, aad A. Dorfman, Biochim. Bioph?/s. Acta, 1964,88, 148.71 A. Linker, W. F. Coulson, and W.H. Cames, J. BioZ. Chem., 1964, 239, 1690.7 2 E. R. Berman, Bbchim. Biophys. Ada, 1965, 101, 358.78 J. Rotstein and J. Seltzer, Bioclzim. Biophys. Acta, 1965, 101, 273.7 4 M. J. Lipson and J. E. Silbert, Bbchim. Biophy#. Acta, 1965, 101, 279.7f, S. Torii, R, I. Bashey, and K, Nakao, Biochim. Biophys. Ada, 1965, 101, 285.7 s I . Danishefsky and A. Bella, Fed. Proc., 1965, 24, 355.?7 3%. D. Clark, J. C. Smith, and E. A. Davidson, Biochim. Bwphys. Acta, 1965,78 J. G. Smith, R. D. Clark, and E. A. Davidson, Fed. Proc., 1965, 24, 558.79 D. F. Wood and P. A. Anastassiadis, Curd. J. Biochem., 1965, 43, 1839.81 J. K. Huttunen and T. A. Miettinen, Acta Chem. Xcarzd., 1965, 18, 1486.Biochirn. Biophys. Actcc, 1965, 101, 160.101, 267.L. C. Ryan, R.Carubelli, R. Caputto, ar,d R. E. Trucco, Biochim. Biophys.Ada, 1965, 101, 252476 BIOLOUICAL CHEMISTRY(lactose sulphate), has also been isolated from lactating-rat mammaryglands.82Other carbohydrate sulphates of mammalian origin are incompletelycharacterised a t present, but enough is known to indicate that some havenew types of structure. A mixture of products from human brain has beenfractionated into a sulphated xylose-rich component and a less acidic ara-binose-containing component. Both contained polypeptide, hexosamine,hexuronic acids, and other sugars. 83 Polysaccharide sulphates from humangastric juice and the gastric wall of the dog gave galactose, fucose, glucos-amine, galactosamine, and sialic acids on hydrolysis. Hyaluronic acid anddermatan sulphate were also present in the latter source.84 Bovine lenscapsule contains a sulphated polysaccharide which has units of galactose,mannose, glucosamine, fucose, and a neuraminic acid derivative.85 Thesulphated glycoproteins from sheep colonic mucin 86 and dog submaxillarygland 87 are particularly interesting because of their possible similarity toknown glycoproteins in function and in general structure.Molluscan polysaccharide sulphates and the associated enzymes, parti-cularly those from the marine gastropod Chronia kcmpas, have been studiedby Japanese workers for many years.A glucan sulphate (named charonin-sulphuric acid) from the mucous glands of this organism has been fraction-ated into (i) a sulphate-poor fraction which is partly hydrolysed by a- and/3-amylases and which gives an iodine coloration similar to glycogen, and(ii) a sulphate-rich fraction which contains ~-1A-linked glucose units.88The sulphate-rich fraction has now been shown to act as an acceptor insulphate transfer from PAPS by an enzyme extract from the mucous glands.89A sulphated glycoprotein, for which the name horatinsulphuric acid is pro-posed, has been isolated from the liver of the same organism.g0 The hypo-branchial gland of the whelk Buccinum undatum L.secretes a mucin whichcontains a glucan sulphate apparently bound covalently to peptide and inloose association with glycoprotein. 91 Sulphsted polysaccharide is similarlysecreted by the hypobranchial gland of another mollusc, Neptunia antiqua ;the component sugars in this case are glucosamine, galactosamine, glucose,and fucose.92 The jelly coat of starfish eggs contain a complex sulphatedpolysaccharide which has galactose and fucose as the major sugar units.93The Linkage of Glycosaminoglycan Sulphates to Protein.-Further evi-8 2 H.8. Barra and R. Caputto, Biochim. Biophys. Acta, 1965, 101, 367.83 Z. Stary, A. H. Wardi, D. L. Turner, and W. S. Allen, Arch. Biochem. Biophys.,84 I. Hiikkinen, K. Hartiala, and T. Terho, Acta Chem. Scand., 1965, 19, 797, 800.8 8 Z. Dische and G. Zelmenis, Fed. Proc., 1964, 23, 319.86 P. W. Kent and J. C. Marsden, Biochem. J., 1963, 87, 38P; P. W. Kent, ibid.,8 7 C. Bignardi, C. Aureli, G. Balduini, and A. A. Castellani, Biochem. Biophys.85 K , Iida, J .Biochem. Japan, 1963, 54, 181; F. Egami, T. Asahi, N. Takahashi,8 9 H. Yoshida and F. Egami, J . Biochem. (Japan), 1965, 57, 215.90 S. Inoue, Biochim. Biophys. Acta, 1965, 101, 16.g1 S. Hunt and F. R. Jevons, Biochim. Bwphys. Acta, 1965, 101, 214; Biochem. J.,Q2 J. Doyle, Biochem. J., 1964, 91, 6P.93 T. Muramatsu, J . Biochem. (Japan), 1965, 57, 223.1965, 110, 388.1964, 90, 1P.Res. Comm., 1964, 17, 310.S . Suzuki, S. Shikata, and K. Nishizawa, Bull. Chem. SOC. Japan, 1955, 28, 685.1966, 98, 522REES : CARBOHYDRATE SULPHATES 477dence to that discussed in last year’s Report,54 points to the existence ofglycosidic linkages between several polysaccharides and hydroxyamino-acidresidues in the protein. The amino-acid units that remained attached tochondroitin 4- and 6-sulphates after digestion of the whole tissue withproteolytic enzymes, were liberated in cold alkali with formation of a-aminoacrylic acid units that were characterised chromatographically asalanine after hydrogenation.This suggests that the amino-acid-containingmaterial had been linked through the hydroxyl group of serine, and wasreleased by #?-elimination. 94 The possibility that it was released by hydro-lysis of an ester link to glucoronic acid was excluded by the failure of thepolysaccharide-protein complex to form a non-dialysable hydra~ide,~~ aswell as by earlier evidence. Three distinct glycosaminoglycan-protein sub-fractions, each of which contains part of the total chondroitin sulphate,are recognisable in bovine nasal cartilage.Two are essentially insolubleand give a product that is very similar to the third (soluble) sub-fractionon very mild treatment with aqueous hydroxylamine or an extraction withpotassium ~yanide.~5 The soluble sub-fraction is electrophoretically hetero-g e n e o u ~ . ~ ~ In an approach to the characterisation of the chondroitin4-sulphate-protein linkage in the soluble sub-fraction, acid hydrolysis ofglycopeptide fragments produced by successive action of testicular hyalu-ronidase and papain gave substances with the properties expected of 0-xylopyranosylserine, O-/3-D-galactopyranosyl- ( 1 +3)-O-~ylopyranosylserine 7and 0-B-D- (glucopyranosyluronic acid)-( 1 -+3)-~-galactose.~8 Together withanalytical data for the glycopeptides, this suggests that the sequence ofunits in the region of the linkage to protein is D-glucuronic acid+2-acet-smido-2-deoxy-~-galactose 4-sulphate -+D-glucuronic acid +D-galactose +D-galactose+xylose-+serine.The model compound O-P-D-xylopyranosyl-L-serine has been synthe~ised,~~ and a xylosylserine has been isolated fromhuman urine.loO Analysis for the N-terminal amino-acids of the residualpeptide chains attached to chondroitin 6-sulphate isolated from sharkcartilage after treatment with proteolytic enzymes, gave no evidence for asingle type of chain.94 Sialic acid is present in connective tissue, and someof it would appear t.0 be bound to the chondroitin sulphate-protein complex,although the exact location is unknown.101The conclusion that chondroitin sulphate is joined to protein through a‘‘ linkage region ” containing sugar units which do not otherwise occur int’he polysaccharide, raises some interesting questions about biosynthesis.The synthesis of chondroitin sulphate by minced embryonic chicken cartilageis inhibited by puromycin, whether the synthesis is measured by incorpor-94 B.Anderson, P. Hoffman, and K. Meyer, J . BioZ. Chem., 1965, 240, 156.95 S. Pal and M. Schubert, J . Biol. Chern., 1965, 240, 3245.g6 T. A. Mashburn, P. Hoffman, B. Anderson, and K. Meyer, Fed. Proc., 1965,97 H. D. Gregory, T. C. Laurent, and L. Rodh, J . Biol. Chem., 1964, 239, 3312;g8 L. RodBn, Fed. PTOC., 1964, 23, 484; L. Roden and 0. Armand, J . Biol. Chern.,sQ B. Lindberg and B.-G.Silvander, Acta Chem. Xcand., 1965, 19, 530.24, 606.L. Roden and U. Lindahl, Fed. Proc., 1965, 24, 606.1966, 241, 65.loo F. Tominaga, K. Oka, and H. Yoshida, J . Biochern. (Japan), 1965, 57, 717.lol A. J. Anderson, Biochem. J . , 1962, 82, 372478 BIOLOGICAL CHEMISTRYation of labelled serine, acetate, or sulphate into the chondroitin sulphatefraction isolated after papain digestion. Puromycin probably interfereswith the synthesis of the protein part of the chondroitin sulphate-proteincomplex. This and other evidence suggests that the biosynthesis involvesaddition of carbohydrate units to preformed protein.102Heparin prepared under mild conditions contains combined amino-acids, with serine as the main component; galactose and xylose units are alsopresent, even after exhaustive purification.lo3 Only traces of amino-acidsare present after more drastic isolation conditions.Partial acid hydrolysisgave products with the properties expected of 0-D-xylosylserine, O-D-galactosyl-0-D-xylosylserine, and glucuronosylgalactose, suggesting that thecarbohydrate-protein linkage is similar to that in the chondroitin sulphates.Serine is a major amino-acid in a heparan sulphate-peptide fraction fromhuman aorta, suggesting that heparan sulphate also occurs bound to proteinthrough a serine unit.lW A similar fraction has been isolated from the liversof patients with the Hurler syndrome, a hereditable disease of connectivetissue (gargoylism) .lo5Dermatan sulphate would also appear to occur normally in the form ofa protein complex.1o6, It can be liberated by treatment with alkalior by exhaustive proteolytic digestion.From the tissues and urine ofpatients with the Hurler syndrome, however, this polysaccharide can bereadily isolated almost free from protein. This suggests that there is ametabolic defect associated with this disease, which results in the failureof dermatan sulphate to be fixed normally in connective tissue.48, lo' Therewould seem to be a similar defect in the linkage of heparan sulphate to proteinin the liver.lo5Recent work suggests that keratan sulphate is linked to protein indifferent ways in different types of tissue (the possibility that the polysac-charide chain might differ in structure from one source to another, has beenmentioned above).After treatment with proteolytic enzymes, differentsamples of keratan sulphate from skeletal tissues usually show similar amino-acid patterns with high contents of glutamic acid, proline, and threonine,whereas aspartic acid is the major amino-acid combined in corneal keratans ~ l p h a t e . ~ ~ , 53 Treatment with alkali has been used to obtain informationabout the carbohydrate-protein linkages,63 as in studies on chondroitinsulphates. Elimination of the 6-sulphate from 1 +&linked glucosamine units(compare refs. 6 and 7) is probably only a minor side-reaction under the mildconditions that are used. The destruction of both serine and threonineunits in skeletal keratan sulphate, with the formation of products that couldbe converted by hydrogenation into alanine and a-aminobutyric acid, in-dicated that some serine and threonine hydroxyl groups were substituted.l o a A.Telser, H. C. Robinson, and A. Dorfman, Proc. Nat. Acad. Sci. U.S.A., 1965,103 U. Lindahl, J. A. Cifonelli, B. Lindahl, and L. Rodbn, J . Biol. Chem., 1965,loC 8. Jacobs and H. Muir, Biochem. J., 1963, 87, 38P.105 J. C. Knecht and A. Dorfman, Fed. Proc., 1965, 24, 606.106B. P. Toole and D. A. Lowther, Biochim. Biophp. A&, 1965, 101, 361.107 A. Dorfman, Biophys. J . , 1964, 4, 155.54, 912.240, 2817; U. Lindahl and L. Roden, ibid., p. 2821REES : CARBOHYDRATE SULPHA‘I‘ES 47 9The production of reducing sugar groups in the reaction suggested that thesubstituents were glycosidic.However, some peptide still remained boundto the polysaccharide, and other types of carbohydrate-peptide linkage aretherefore likely to be present. The relative importance and relative r6lesof these different types is undecided. In contrast, the amino-acid contentof corneal keratan sulphate was not decreased by alkali treatment. If allthe polysaccharide chains of corneal keratan sulphate were linked to peptide,and bylinkages of a single type, analysis after papain treatment andextensivepurification would indicate that aspartic acid is the only amino-acid presentin sufficient amount to give the necessary number of attachment points.58There is some chemical evidence consistent with the presence of glycosyl-amine linkages to asparagine in corneal keratan ~ulphate.~~ For skeletalkeratan sulphate, similar arguments from analytical data 52 suggest thatthreonine, proline, or glutamic acid, but not aspartic acid, could providethe attachment points.Non- covalent interactions between glycosaminoglycans and protein arealso important from a biological point of view.Such interactions withcollagen, which are probably largely electrostatic, might have a r61e in theorganisation of connective tissue. Free-solution electrophoresis has shownan apparent gain in stability of the collagen complex with increasing mole-cular weight of the polysaccharide, suggesting a parallel alignment of chainsin the complex. The polysaccharide side-chains of the chondroitin sulphate-non-collagenous protein macromolecule might therefore lie parallel withcollagen in connective tissue.lo8 Chondroitin sulphate-protein macro-molecules also complex with plasma proteins and with glycoproteins ofsufficiently low sialic-acid content. These effects are also explained in termsof electrostatic interactions.logPolssaccharide Sulphates from Seaweeds.-Most classes of marine algaeseem to contain polysaccharide s u l p h a t e ~ .~ ~ ~ ~ The discussion here willbe confined to recent progress in the polysaccharide sulphates from theRhodophyceae (red seaweeds) and the Chlorophyceae (green seaweeds) be-cause it is with these that most recent work has been done. Other types ofpolysaccharide sulphate have been isolated from the Phaeophyceae (brownseaweeds),llO and from a marine diatom.ll1Red seaweeds.These sulphated polysaccharides are usually galactansof a well-defined structural type, which nevertheless have many remarkablediEerences.l12 The molecule commonly has galactose units linked a-l+3and ,!I-1 4 in alternating sequence. Among the variations are the presenceof the 4-linked galactose units as the D- or the L-enantiomorph, as the 3,6-anhydride of either enantiomorph, or as the 6-sulphate or 2,6-disulphate.The 3-linked unit is usually D-galactose which may be 2- or 4-sulphated, orlo* M. B. Mathews, Biochem. J., 1965, 96, 710.loo A. J. Anderson, Biochem. J . , 1965, 94, 401; ibid., 1965, 97, 333.logs S. Peat and J. R. Turvey, Portschr. Chem. org. Natwrstofle, 1965, 23, 1.R. H. CBt6, J . Chem. Soc., 1959, 2248, and references given there; B.Larsen,A. Haug, and T. J. Painter, in “Proceedings of the V International Seaweed Sym-posium,” eds, E. G. Young and J. L. Mclachlan, Pergamon, 1966, p. 287.ll1 C. W. Ford and E. Percivd, J . Chem. SOC., 1965, 7042.112 N. S. Anderson, T. C. S. D o h , and D. A. Rees, Nature, 1965, 205, 1060; andreferences given there480 BIOLOGICAL CHEMISTRY6-O-methylated. Some of the known polysaccharides of this type areshown in Table 2. There are some polysaccharides, such as the mucilageof DiEsea edulis (= D. carnosa),6, lI3 which might not fit this pattern. Forseveral of these polysaccharides, quantitative comparison of the productsof partial fragmentation of the suitably modified polysaccharides with thosefrom disaccharide 115 together with other evidence,114 has shownthat there can be little if any deviation from a strictly alternating arrange-ment of 1+3 and 1 4 linkages. This alternating arrangement of thesugar units may however be masked by units within the 3-linked series andwithin the 4-linked series being present as different derivatives.For ex-ample, different samples of porphyran (1) have the component units (D-galactose, 6-O-methyl-~-galactose, 3,6-anhydro-~-galactose, and L-galactose6-sulphate) present in widely varying proportions, and the alternating struc-ture is thus overlaid by substitution and modification. The alternatingCH2OH H CHzOMe H0‘ H OM? H OMe ‘ “-‘O H(2)struct,ure was proved by conversion into niethylated agarose (2) by alkalineelimination of the 6-sulphate followed by methy1ati0n.l~~ The structureof agmose, its methylated derivative, and various fragments derived fromeach, had previously been established by Araki’s classical work.l16The carrageenans are examples in which the 4-linked units are present113 1’.C. Barry and J. E. McCormick, J. Chem. Soc., 1957, 2777.114 N. S. Anderson and D. A. Rees, J . Chem. SOC., 1965, 5880.115 N. S. Anderson and D. A. Reesin in“ Proceedings of the V International SeaweedSymposium,’’ eds. E. G. Young and J. L. McLachlan, Pergamon, 1966, p. 243.1l6 C. Araki and S . Hirase, Bull. Chem. SOC. Japan, 1960, 33, 597, and referencesgiven there: see also G. Araki in “ Proceedings of the V International Seaweed Sym-posium,” eds.E. G. Young and J. L. McLachlan, Pergamon, 1966, p. 3AgaroseTABLE 2 Structural variations on the thewe [P-Galp-(l--+ 4)-ac-Galp-( 1 --+ 3)Derivatives of the Derivatives of the 4-3-linked galactose iiriit galactose unitD-Galactose 3,6-Anhydro-L-galactosePorphyrenK- Carrageenann -Galactose, 6-0 -meth yl-D -galactosen - Gnlac t osc 4 -sulphat,eA-Carrageenan D -Galactose ;Third component of D Galactose ; n-galactoseChondrus carrageenan 4-sulphateFur cellarnn D-Galactose (some as branchpoints through position 6);D -galactose 4-sulphateD -Galactose 2 -sulphate3, 6-Anhydro an galactose ; L-galactose3,6-Anhydro-~ -galactose ; D -galactosegalactose 2,6-disulphate ; (probably)galactose 2-sulphateD-Galactose 2,6-disulphateD -Galactose 6 -sulphate ; (probably)galactose ; (perhaps) D-galactose3,G-anhydro -D -galactose 2 -sulphate3,6-Anhydro-u-galactose ; D-galactoseD -galactose 2,6-disulphate ; (perhaps)galactose 2-sulphateNotes.References are givcn in the test. There are probably many other polysaccharides of this type, thoughthose in this Table (see ref. 112 for discussion of this point)482 BIOLOGICAL CHEMISTRYas D-enantiomorphs. These polysaccharides are usually obtained byfractionation of Chondrus crispus extracts, but it is probable that there arestructurally similar polysaccharides in some other species. Methylationanalysis of hamageenan, before and after desulphation, established thatthe 3-linked units are mainly 2-sulphated with some being 4-sulphated andsome non-sulphated, and that the 4-linked units occur mainly as D-galaCtOSe2,6-di~ulphate.~~ After alkali-catalysed conversion of the 4-linked unitsinto 3,6-anhydrogalactose (mostly in the form of its 2 sulphate), the productwas separated into two fractions.All the 3-linked galactose 2-sulphatewas present in one fraction (“ alkali-modified 1-carrageenan ”), and all the4-sulphate in the other ( ‘ I alkali-modified third component of Chondruscarrageenan ”). The 4-linked units are less extensively 2-sulphated in thethird component derivative. Both fractions contain non-sulphated 3-linkedunits, and both have structures corresponding closely to a perfect alternationof 1 4 and 1 4 linkages.l15, 117 It is suspected that the variable propor-tions of 3,6-anhydrogalactose often found in crude A-carrageenan 7,118 isassociated with the native third component.K-Carrageenan also has aperfect, or near-perfect, alternating structure.ll5 Methylation l 1 7 showsthat the 3-linked units occur virtually completely as D-galactose 4-sulphatewhereas the 4-linked units occur as 3,6-anhydro-D-galactose and probablyto some extent as its 2-sulphate. The presence of relatively minor amountsof 4-linked galactose 6-sulphate and 2,g-disulphate has been shown byalkaline elimination of the 6-sulphate coupled with the use of periodateoxidation and partial fragmentation.ll5 Part of the K- carrageenan moleculeis resistant to bacterial K-carrageenase, but alkali treatment of the residue,which results in a rise in the proportion of 3,6-anhydrogalactose7 rendersit susceptible.11s This behaviour is readily explained in terms of the structureput forward.Further conhation of this structure is the paper-chromato-graphic identification of the expected monosaccharide sulphates after partialhydrolysis.l20 A similar polysaccharide to K-carrageenan, but which differsin being branched and less sulphated, is extracted from Furcellaria fmti-giata.112~ 121 The recent confirmation 122 of the structure of carrabiose (3,6-anhydro-4-O-/3-~-galactopyranosyl-~-galactose) 123 means that the 1 4 -linkage in the carrageenan family of polysaccharides is more firmly estab-lished. A painstaking survey has provided very useful information aboutthe distribution and variation of carrageenan-type polysaccharides.ll* Thedegree of the variation suggests that the carageenans are very variable withrespect to their content of particular structural features.It is possible thatfurther distinct fractions will be recognised in the future.11’ T. C. S. Dolan, Ph.D. Thesis, Edinburgh, 1965.118 W. A. P. Black, W. R. Blakemore, J. A. Colquhoun, and E. T. Dewar, J. Sci.Food Agric., 1965, 16, 573.llS J. Weigl, J. R. Turvey, and W. Yaphe in “ Proceedings of the V InternationalSeaweed Symposium,” eds. E. G. Young and J. L. McLachlan, Pergamon, 1966, p. 329;J. Weigl and W. Yaphe:‘Canczd. J . Microbiol.. in the press.leo T. J. Painter, in Proceedings of the V International Seaweed Symposium,”eds. E. G. Young and J. L. McLachlan, Pergamon, 1966, p.305.121 J. Christensen and A. Haug, personal communication.la2 T. J. Painter, J. Chem. Soc., 1964, 1396.12* C. Araki and S. Hirase, Bull. Chem. SOC. Japan, 1956, 29, 770REES : CARBOHYDRATE SULPHATES 483Only limited information is available on the biosynthesis of red seaweedgalactan sulphates. The nucleotides present in Porphyra perforata, an algafrom which porphyran (1) may be extracted, include uridine diphosphateD-galactose and guanosine diphosphate ~-galactose.l~* The latter may arisefrom guanosine diphosphate D-mannose, which was also isolated, becausetransformations similar in some respects to those required for this con-version are known to occur elsewhere. Porphyra extracts contain an enzymewhich catalyses the conversion of L-galactose 6-sulphate units into 3,6-anhydro-L-galactose a t the polysaccharide level.125 Porphyran is a muchbetter substrate than oligosaccharides containing L-galactose 6-sulphateunits.These facts, together with the variation in porphyran compositionwhich is very wide indeed, but which apparently occurs without abolishingthe perfect alternation of D- and L-units, suggest that 3,6-anhydride form-ation and perhaps also 6-O-methylation occur after formation of the poly-saccharide chain.126 The most likely route for porphyran biosynthesiswould therefore be synthesis of a DL-galactan from uridine diphosphateD-galactose and guanosine diphosphate L-galactose, perhaps by way of anintermediate disaccharide derivative,l26a followed by sulphation, partialmethylation, and 3,6-anhydride formation from some of the sulphatedunits. The last three steps could, of course, occur in a different order.Itmay be noted that nucleotide derivatives of 3,6-anhydrogalactose and 6-O-methylgalactose were not detected in P. ~erforata.1~~ Attempts to demon-strate the enzymic transfer of methyl groups from X-adenosylmethionine toporphyran by Porphyra extracts have met with no In Lomentariabaileyana, there is evidence that the Golgi apparatus has a function in thesynthesis and deposition of a substance into the cell walls that might be agalactan sulphate.128The close structural relationships between the three co-occurring carra-geenans suggest that they are interconverted to some extent in &vo, or thatthey have a common precursor such as a galactan or a galactan 6-sulphatewhich gives rise to the known polysaccharides by further sulphation and, inthe formation of K-carrageenan only, 3,6-anhydride formation.In con-nexion with the first possibility, the interconversion of K- and A-carrageenanswould require extensive rearrangement of sulphate groups in addition toother changes, and the conversion of either of these into the ‘‘ third com-ponent ” would require rearrangement of sulphate groups or opening of the3,6-anhydro-ring. It is therefore perhaps likely that both K-carrageenan andA-carrageenan are (relatively) end-products of biosynthesis, which might,however, undergo metabolic alteration in wivo to a small extent. Never-theless, the structure of the ‘‘ third component ” suggests that it might verywell be a precursor of K-carrageenan. An earlier suggestion 7 that A- might1 2 p J.C. Su and W. Z. Haasid, Biochemistry, 1962, 1, 474.125 D. A. Rees, Biochem. J., 1961, 81, 347.lZ6 D. A. Rees and E. Conway, Biochem. J., 1962, 84, 411.Compare J. M. Weiner, T. Higuchi, L. Rothfmld, M. Saltmarsh-Andrew, M. J.Osborn, and B. L. Horecker, PTOC. Nut. Acad. Sci. U.S.A., 1965, 54, 228; A. Wright,M. Dankert, and P. W. Robbins, {bid., p. 235.127 D. A. Rees, unpublished work.l a s G. B. Bouck, J . Cell Biol., 1962, 12, 553484 BIOLOGICAL CHEMISTRYbe a precursor of K-carrageenan was made before the distinction betweenA-carrageenan and the third component became clear.Green seaweeds. Polysaccharide sulphates from these sources are complexand no overall picture is yet available of their structures.There has, how-ever, been substantial recent progress in locating the sulphate esters. Methy-lation 129 has shown that the sulphated polysaccharide from Enteromorpha(probably representative of a group of polysaccharides all composed mainlyof xylose, rhamnose, and glucuronic acid units, as well as having other featuresin common 5 9 I3O) has a complicated structure, because the neutral sugarunits each occur in several different structural situations. The sulphatedpolysaccharides of Codium f r q i l i contain galactose and arabinose as themajor units. The nature of some of the glycosidic linkages and the locationof some of the sulphate has been shown by the isolation of 3-O-/?-~-arabino-pyranosyl-L-arabinose, 3 -O-/?-D -galactopyranosyl-~ - galactose, D - galactose.Q-sulphate, and D-galaCtOSe 6-sulphate as partial hydrolysis products.l31The water-soluble sulphated polysaccharides from Cladophora rupestris,Chaetomorpha liaum, and Ch.cupilhris are similar to each other.132 Theysuperficially resemble those from Codium in containing galactose and ara-binose as the major sugar components and ingiving 3-O-~-~-galactopyranosyl-D-galactose and galactose 6-sulphate on partial hydrolysis. Differencesare shown, however, by the isolation of further products not given by theCodium polysaccharides, namely 6-O-~-~-galac~opyranosy~-D-ga~ac~ose, L-arabinose 3-sulphateY and an O-L-a.rabinopyranosy1-L-arabinosc 3-sulphatethat was either 1 4 - or 1+5-linked.Another difference was that 3-0-8-~-arabinopyranosyl-L-arabinose and galactose 4-sulphate were not isolated.The presence of L-arabinose 3-sulphate units which must be unsub-stituted on C-2 in the Cladophora polysaccharide, was confirmed by theisolation of 2-O-methyl-L-xylose, formed by ring-opening of an intermediate2,3-epoxideY after treatment with sodium rnethoxide followed by acidhydrolysisCarbohydrate Sulphates in Lipids.-Sulphatides. A brief summary hasbeen published of the chemistry and natural distribution of these glycolipidscontaining sugar sulphate units,133 and this discussion is confined to subse-quent work. Further confirmation that cerebroside sulphate from bovinebrain contains a 3-sulphated rather than a 6-sulphated galactose unit, isthat the natural product is not identical with a sulphation product of cere-broside in which the galactose was shown by methylation t o be 6-~u1phated.l~’Sulphate is solely a t this position in brain sulphatides from normal humanadult, normal infant, and from the infantile form of metachromatic leuco-dystrophy-a disorder in which there is an accumulation of ~u1phatides.l~~There are differences in fatty-acid composition between cmebroside sulphateslZe C.C. Gosselin, A. Holt, and P. A. Lowe, J . Chem. Soc., 1964, 5877.130 J. P. McKinnell and E . Percival, J . Chem. Soc., 1962, 2082; J. J. O’Donnelland E. Percival, ibid., 1959, 2168.131 J. Love and E. Percival, J . Chem.SOC., 1964, 3338.132 Sir Edmund Hirst, W. Mackie, and E. Percival, J . Chenz. Soc., 1965, 2958.13s A. N. Davison, Biochem. J., 1964, 91, 3P.13* T. Taketomi and T. Yamakawa, J . Biochem. Japan, 1964, 55, 87.135 M. MaIone and P. Stoffyn, Biochim. Biophys. Aeta, 1965, 98, 218REES : CARBOHYDRATE SULPHATES 485from different S O U ~ C ~ S . ~ ~ ~ , 136 Cerebroside, but not cerebroside sulphate, isoxidised by the galactose oxidase of Polyporus eircinatus (= Dactyliumdendroides), presumably at C-6 of the galactose ~ n i t . l 3 ~ It has been con-firmed that there is a cerebroside sulphate in human kidney which is similarto that of the brain.138 Methods for the fractionation of brain sulphatideshave been discussed in relation to the isolation of ~u1phatides.l~~Suggestions based on tracer evidence 14O that cerebrosides are the pre-cursors of cerebroside sulphates are now supported by the formation ofcerebroside sulphate by sulphate transfer from PAPS, apparently to cere-broside, by enzymes from sheep 141 and rat 142 brains.Transfer by the sheep-brain extract requires a protein-bound acceptor.141This sulpholipid occurs in all or almost all greentissues and is entirely different from the sulphatides of animal origin.143 Prooftha,t it is a derivative of 6-sulpho-6-deoxy-a-~-glucopyranosyl-( 1 + l ) - ~ -glycerol has been derived from its reacti0ns,l4~ partial synthesis,144 andX-ray analysis of the rubidium salt of the deacylated derivative.l45 Thefatty-acid composition is similar to the phosphatides, but contains a higherproportion of saturated acids than most other leaf 1 i ~ i d s .l ~ ~ The compoundmight have a function in photo~ynthesis.~~~ Plant tissues are unable tosynthesise a selenium-containing analogue, and it has been argued thatthis 148 and other evidence 14Sa might suggest that the biosynthesis involvesPAPS. Biosynthesis of the sulphodeoxy-sugar probably occurs at or beforethe level of the sugar nucleotide, and is followed by transglycosylation toform the li~id.1~~7 148a The bacterial degradation does not appear to involveprior desulphonation, becausg sulpho-acetic acid is formed, and this maythen be metabolised further.149The Synthesis and Reactions of Simple Carbohydrate Su1phates.-Thepreparation and properties of sugar sulphates have been thoroughly re-~ i e w e d .~ Direct sulphation of the primary hydroxyl groups of sugarderivatives is usually specific enough to be a convenient preparative method.136 J. S. O’Brien, D. L. Fillerup, and J. F. Mead, J . Lipid Res., 1964, 5, 109; J. S.O’Brien and G. Rouser, ibid., p. 339.13’ R. M. Bradley and J. N. Kanfer, Biochim. Biophys. Acta, 1964, 84, 210.13* A. Makita, J. Biochem. Japan, 1964, 55, 269; A. Makita and T. Yamakewa,ibid., p. 365.lS0 S. Yokoyama and T. Yamakawa, Jap. J . Exp. Med., 1964, 34, 29; J. Dittmer,Biochim. Biophys. Acta, 1965, 106, 425.140 N. S. Radin, F. B. Martin, and J. R. Brown, J . Biol. Chem., 1957, 224, 499;I. H. Goldberg, J. Lipid Res., 1961, 2, 103; G. Hauser, Biochim. Biophys. Acta, 1964,84, 212; Y.Kishimoto, W. E. Davies, and N. S. Radin, J. Lipid Res., 1965, 6, 525.141 A. S. Balasubramian and B. K. Baehhawat, Biochim. Biophys. Acta, 1965, 108,218.la2 G. M. McKhann, R. Levy, and W. Ho, Biochem. Biophys. Res. Comm., 1965,143 A. A. Benson, Adv. Lipid Res., 1963, 1, 387; Ann. Rev. Plant Physiot., 1964,144 J. Lehmann and A. A. Benson, J. Amer. Ckem. Soc., 1964,8$, 4469, and referencesla5 Y. Okaya, Acta Cryst., 1964, 17, 1276.146 J. S. O’Brien and A. A. BensQn, J. Lipid Res., 1964, 5, 432.14’ A. A. Rosenberg and M. Peeker, Biochemistry, 1964, 3, 254.148 P. Nissen and A. A. Benson, Biochim. Biophys. Acta, 1964, 82, 400.148a W. H. Davies. E. I. Mercer, and T. W. Goodwin, Biochem. J., 1966, $8, 369.14g H. L. Martelli and A. A.Benson, Biochim. Biophys. Acta, 1964, 95, 169.The Phnt sulpholipid.20, 109.15, 1.given there486 BIOLOGICAL CHEMISTRYThe products of direct sulphation of N-acetylglucosamine and N-acetyl-galactosamine have recently been characterised more fully as the 6-sulphates.150The 6-sulphates of 2 - acetamido-Z-deoxy- a-~-galactose 1 -phosphate, O-P-D-(glucopuvranosyluronb acid)-( 1 -+3)-2-acetamido-2-deoxy-~-galactose and(uridine diphosphate)-2-acetamido-2-deoxy- a-D -galactose, have been syn-thesised by direct sulphation.151 When the amino-function in aminodeoxy-sugars is not protected, selective N-sulphation can be achieved; this principlehas been used in the synthesis of the labelled compound 2-deo~y-[2-~~S]sulpho-amino-D -glucose .15 The product of direct sulphation of 5,6- O-isopropyli-dene-L-ascorbic acid, which contains no primary hydroxyl, is presumed tobe the 3-sulphate because the 3-hydroxyl is more acidic than the 2-hydroxylwhich is also available for sulphation. The rapid de-esterification of thiscompound by mild oxidising agents suggests an analogy with oxidativepho~phory1ation.l~~The action of sulphuryl chloride on carbohydrates gives a complex mixtureof products by reactions that have only recently begun to be understood.lNChlorosulphate esters are formed h t and can undergo several furtherreactions depending on the conditions. The stereochemistry of the chloro-sulphate ester is particularly important in determining the course of sub-sequent reactions.In an excess of pyridine, hexoside and hexitol derivativeswith vicinal chlorosulphate ester groups may react to give cyclic sulphateesters, except where the groups are diaxial, when the product is an epoxide.An epoxide can be formed from a diequatorial compound by the use of astronger base such as methoxide.The reaction of axial-equatorial vicinalchlorosulphate esters gives (in addition t o cyclic esters) keto-sugars whichare products of olefin-forming elimination followed by ketonisation. InH H CICI H Hcertain circumstances, the chlorosulphate groups may be converted intochlorodeoxy-groups with inversion of configuration. This nucleophilic dis-placement by chloride may be prevented by steric interactions which increasethe energy of the transition This displacement seems rarely tooccur at C-2 of the sugar ring, presumably because of electronic effects.The unsaturated disaccharide (3) is one of the products of the action ofsulphuryl chloride on arabinose, but the reactions leading to its formationare not fully understood.Is* E.Meezan, A. H. Olavesen, and E. A. Davidson, Biochim. Biophys. Acta, 1964,151 A. H. Olavesen and E. A. Davidson, Biochim. Biophy8. Acta, 1965, 101, 245.1 5 2 A. G. Lloyd, F. S. Wusteman, N. Tudball, and K. S. Dodgson, Biochem. J . ,ls3 E. A. Ford and P. M. Ruoff, Chem. Comm., 1966, 630.lS4 H. J. Jennings and J. K. N. Jones, Canad. J . Chm., 1966, 43, 2372, 3018, and15*5A. G. Cottrell, E. Buncel, and J. K. N. Jones, Ohm. and I&., 1966, 552.83, 256.1964, 92, 68.earlier papersR E E S : CARBOHYDRATE SULPHATES 487In the hydrolysis of certain hexitol cyclic sulphates by hot dilute acidthere is an initial rapid formation of anhydroalditol sulphate half-esterswhich indicates that the cyclic sulphate is opened by intramolecular nucleo-philic displacement with C-0 cleavage and inversion a t carbon.155 Thesulphate half'ester is then, as usual, hydrolysed relatively slowly with S-0cleavage.1ti6 J.S. Brimacombe, M. E. Evans, A. B. Foster, and J. M. Webber, J. Chm. Soc.,1964, 27355. PROTEINS AND PEPTIDESBy D. G. Smyth(National Institute for Medical Research, Mill Hill, London. N . W . 7)PROGRESS in the field of protein and peptide chemistry has again beenextensive. Striking similarities in the molecular behaviour of proteins havebeen noted in diverse biological fields.In Molecular Immunology, the struc-ture of antibody and the binding of antigen to antibody have found corollaryin Molecular Endocrinology with the structure of peptide hormone and itsbinding to receptor, and in Molecular Enzymology wit'h the structure ofenzyme and its binding and activation of substrate. At the molecular level,function is structure and change of structure. The rapid advances currentlybeing made in elucidating the amino-acid sequence and spatial conformationof complex protein and peptide molecules are therefore of fundamentalimportance.This year, the complete amino-acid sequence of sperm whale myoglobin 1(153 residues) has been presented, with definitive experimental daka.Thetotal sequence of ribonuclease-T, (ref. 2) (104 residues) and the almostcomplete sequence of papain (198 residues) have been elucidated. Preli-minary amino-acid sequences of two Type I Bence-Jones proteins 47 5 (212residues) have been proposed ; these, together with comparative studies onpartial sequences of other Bence-Jones proteins,6 provide a first insight intothe detailed structure of y-globulin. The #?-Lipotropic hormone (90 residues)has been isolated and its sequence determined.8 Thyrocalcitonin (86residues) and parathyroid hormone l o (ca. 60 residues) have been isolated;no detailed sequence studies have yet been reported. The peptide hormone,secretin (27 residues), has been isolated and much of its sequence deduced.11The structure of tyrocidine-C (10 residues) has been established.l2 The fieldis open for relating the physiological function of these molecules to theirchemical structures.y-Globulin.-It has been axiomatic that a protein should be availablein pure form before a detailed study of its structure is undertaken.Thusthe well-known heterogeneity of y-globulin has, in the past, diminished theincentive for investigation of its amino-acid sequence. In contrast Bence-A. B. Edmundson, Nature, 1965, 205, 883.K. Takahashi, J. Biol. Chem., 1965, 240, 4117.A. Light, R. Frater, J. R. Kimmel, and E. L. Smith, Proc. Xut. Acad. Sci.S. Hilschmann and L. C. Craig, Proc. Nut. Acad. Sci. U.S.A., 1965, 53, 1403.j K. Titani, E. Whitley, L. Avogardo, and F.W. Putman, Science, 1965, 149,C. Milstein, Nuture, 1966, 209, 370.Y. Birk and C. H. Li, J . BioE. Chem., 1964, 239, 1048.C. H. Li, L. Barnafi, M. ChrBtien, and C. Chung, Nature, 1965, 208, 1093.V. Mutt, S. Mapusson, J. E. Jorpes, and E. Dahl, Biochemistry, 1965, 4, 2358.lo M. A. Ruttenberg, T. I?. King, and L. C. Craig, Biochemistry, 1965, 4, 11.l1 A. Tenehouse, C. Amaud, and H. Rasmussen, Proc. Nut. Acad. Sci. U.S.A.,l2 H. Rasmussen, Y. Ling-Sze, and R. Young, J . Biol. Chenz., 1964, 239, 2852.U.S.A., 1964, 52, 1276.1090.1965, 53, 818SMYTH: PROTEINS AND PEPTIDES 489Jones proteins, which have been shown to be L-peptide chains derived frommyeloma y-globulin,l3-17 can be obtained in homogeneous form when iso-lated from a single individual.Studies on the amino-acid sequences ofBence-Jones proteins 4, 59 18? l9 are therefore practicable and are allowing afirst insight into the detailed structure of the L-chains of y-globulin.Dia.gramma.tic structure of Human y-GlobulinGlu S-S s-s1 1 t 1 , L-chain: K - or A-I sASP s (Bence-Jones protein)I H-chain: p, a-, or p - [ Is1 carbohydrateS ' H-chain I [ssAsp ' K- or il-chain i l s-s I IGlu S--SOn the basis of differing antigenic characteristics of Bence- Jones pro-tein~,22-~~ two distinct types of L-chain have been recognised: Type I orkappa, and Type I1 or lambda.25 The combination of two L-cha,ins K- or2-) with two H-chains (y, a-, or p) is currently considered to provide thefundamental skeleton of the 4-chain y-globulin molecule.(The diagram-matic structure shown is adapted from Fleischmann, Porter and Press; 2oEdelman and Benacerraf; 21 and Milstein 19).L-Chains. The two types of L-chain, studied as the kappa and lambdachains of Bence-Jones proteins, differ completely from each other in ter-minal NH,- groups, peptide maps, and composition of tryptic peptides;26, 27l3 G. M. Edelman and M. D. Poulik, J. Exp. Med., 1961, 113, 861.l4 G. M. Edelman and J. A. Gally, J. Ezp. Ned., 1962, 116, 207.l 5 X. Cohen, Biochem. J., 1963, 89, 334.l6 J. H. Schwartz and G. M. Edelman, J. Exp. Med., 1963, 118, 41.l7 F. W'. Putnam, Biochem. Biophys. Acta, 1962, 63, 539.l8 C. Milstein, J. Mol. Biol., 1964, 9, 836.lS C. Milshin, Nature, 1965, 205, 1171.2o J. B. Flekchmann, R.R. Porter, and E. M. Press, Biochem. J., 1963, 88, 220.21 G. M. Edelman and B. Benacerraf, Proc. Nut. Acad. Sci. U.S.A., 1962, 48, 1035.2 2 M. Mannik and H. G. Kunkel, J. Exp. Med., 1962, 116, 859.23 J. L. Fahey, J . Immzcnol., 1963, 91, 438.24 S. Migita and F. W. Putnam, J. Exp. Med., 1963, 117, 81.Z 5 World Health Organization, Bull. IVorld Health, 1964, 30, 447.26 F. W. Putnam and C. W. Easley, J. BWE. Chem., 1965, 240, 1626.27 K. Titani and F. W. Putnam, Science, 147, 1304400 BIOLOGICAL CHEMISTRYa K-chain thus possesses a totally different amino-acid sequence from a 2-chain. Furthermore, even within Bence-Jones proteins of the sameantigenic type-among K- chains for example-although there are basicsimilarities, considerable differences in primary structure occur.&hains,obtained as Bence- Jones proteins from many different individuals, presentcertain peptide areas of striking identity, certain areas of marked similarity210FIG. 1. Comparison of the amino-acid sequences of three Type I Bence-Jones proteins.Known sequences are indicated by joining together the abbreviations for the amino-acids by dashes. Areas of undetermined sequence are enclosed by a horizontal dashedline. In cases of known composition, the amino-acid residues are placed in the orderof their elution from the column of the analyser if the sequence is unknown for anyprotein; however, if the sequence is known for one protein, the residues enclosed bya dashed line (undetermined sequence) are ordered to correspond with the knownsequence.Regions of probable homologous or nonhomologous interchanges are em-phasiaed by enclosure in a box with a solid line. Regions of possible interchange areenclosed with a vertical dashed box. Data for specimens Roy and Cu are derivedfrom the report by Hilschmann and Craig,4 and data for specimen Ag from Titani,Whitley, Avogardo, and P ~ t n a r n . ~[Reproduced, with permission, from K. Titani, E. Whitley, L. Avogardo, andF. W. Putman, Scimce, 1965, 149, 1090.SMYTH: PROTEINS AND PEPTIDES 491containing identical or homologous amino-acids, and certain areas notablefor the lack of common structure. The question mark over the areas ofdisparity is whether their amino-acid sequences represent the molecular basisthat is critical for the functioning of different antibody molecules, or whetherthere is a degree of freedom a t these positions when the molecule is func-tionally active, making the necessity for precise structure unimportant.The answer to these problems will be found when the amino-acid sequence of alarge number of Bence- Jones proteins from different individuals is obtained,and structure related to differing function.The total amino-acid sequence of a Bence-Jones protein has not yet beenachieved, but almost complete sequences have been presented from twolaboratories (Figure 1).In the studies of Hilschmann and Craig: and ofPutnam and his colleague^,^ preliminary amino-acid sequences have beenproposed for three different Type I Bence-Jones proteins [obtained fromindividuals designated Ag, Roy, and Cummings (Cu)].The protein from asingle individual was found to possess a characteristic amino-acid sequence.With the exception of an interchange of valine for leucine at position 189,an identical sequence of 105 amino-acid residues was found a t the C0,H-terminus in the proteins Ag and Roy, and also in the protein Cu for which lessdata is available. The NH,-terminal portion of the three K-chains, on theother hand, shows markedly less correspondence. The replacements involveboth homologous and non-homologous amino-acids, the differences beingdistributed in a complex manner along the peptide chain.Bence-Jones proteins have been shown to occur as stable monomers,stable dimers, and as dissociable dimers.28? 29 The relationship between thefirst two of these structures and the single chain of amino-acids shown inPigure 1 has recently been elucidated 6 s l9 (Figure a), and further evidencehas been obtained to show that the cystine residue a t the COOH-terminus ofthe K- or ).-chain of Bence-Jones protein is the same residue that is involvedin the linkage of L-chains to H-chains in the heterogeneous y-globulinmolecule.Methods have been developed for radioactive labelling of thecystine residues in Bence-Jones protein and for rapidly determining thesequence of amino-acids around the labelled residues.6 In this manner, theconstant sequence of 24 amino-acids a t the C0,H-terminus has now beenconfirmed for the K-chains from 8 individuals.Another area common to theK-chains from 5 individuals is the sequence from position 115 to 133 (c$Figure 1). The sequence from 84 to 101 was common to three proteins, butthree other proteins showed minor changes in this region, homologous exceptin one case for the replacement of glycine by proline. Finally, a high degreeof correspondence was observed in the sequence from position 17 t o position36.The widespread structural differences among K-chains are clearly notcompatible with their development from a common precursor by single pointmutations, as is believed to be the case with the abnormal haemoglobins. Toallow a clear understanding of the basis for the remarkable variability inthe L-chains of y-globulin, total amino-acid sequences of a large number of28 J.A. Gally and G-. M. Edelman, J. Exp. Med., 1964, 119, 817.G. M. Bernier and G. M. Edelman, Nature, 1963, 200, 223492 BIOLOGICAL CHEMISTRYTYP INH, 212I Stable monomer Lys*Ser *Phe*Asp*Arg*Gly-Glii*Cys1CYSNHZIStable dimer Lys*Ser.Phe*Asp*Arg*Gly.G;luCysI NHZI Lys*Ser *Phe*Asp -Arg*Gly -Glu-Cys212Lys *Ser *Phe*Asp*Arg *Gly *Glu*Cys1NH2Iy-GlobulinH-chainType IIStable monomer Lys *Thr .Val.Ala-Pro.Thr .Glu-Cys*SerIcys.Stable dimer Lys *Thr *Val*Ala*Pro *Thr*Glu*Cys*SerLys-Thr *Val*Ala*Pro -Thr *Glu*Cys*Ser.Lys -Thr *Val*Ala*Pro *Thr -Glu*Cys *Ser y -Globulin1H-chainFIG. 2. Proposed structure around the interchain disulphide bridgein Bence-Jones proteins and in human y - g l o b ~ l i n .~ ~Bence- Jones proteins of the two antigenic types will be required. Meanwhile,further rapid methods are needed for comparative study of the loci of changesand variations in sequence.H-Chain. Studies on the H-ohain of y-globulin are less advanced. TheH-chains of human y-globulin have been found to be electrophoreticallyheterogeneo~s.~~ The detailed studies of Tanford and his ~olleagues,~~however, have shown that a large part of the H-chain in rabbit y-globulinhas a constant structure, and that this structure is the same in antibodyy-globulin. This section of the H-chain comprises all, or nearly all, of thatportion of the H-chain which is present in the papain-produced ‘‘ Fragment111,” but some peptides of “ Fragment I ” are also included in the constantsection.The differences in amino-acid sequence between H-chains thusappear to arise in a relatively small portion of the chain. In this connexion3 0 S. Cohen and R. R. Porter, Biochem. J . , 1964, 90, 278.31 C. A. Nelson, M. E. Noelken, C. E. Buckley, C. Tanford, and R. L. Hill, Bio-chemistry, 1965, 4, 1418SMYTH: PROTEINS AND PEPTIDES 493it may be noted that only very slight differences could be detected betweenpeptide maps from rabbit antibody and the corresponding maps from non-specific rabbit y-gl~bulin.~~Studies leading to the formulation of a sequence in the Fragment I11portion of an H-chain from rabbit y-globulin are in progress in the laboratoryof R. L. Hill.33 A tripeptide, Pro*Val*Thr., has been isolated from an enzymicdigest of the H-chain obtained from a human pathological immun~globulin,~~and evidence was presented that this sequence is derived from the NH2-terminus; the peptide could not be detected, however, in normal humanimmunoglobulin.In studies on the C0,H-terminus of the H-chain ofrabbit immunoglobulin,35 application of the cyanogen bromide technique 36for specific cleavage a t methionine residues yielded an 18 amino-acid peptidein good yield:NH, NH2I I* * * (Met) ~His~Glu*Ala~Leu~His~Asp~His~Tyr~Thr~Glu*Lys~Ser~ileu~Ser*Arg~Pro *GlyCO,HAn almost identical octa,decapeptide was isolated from human myelomaH-chain,37 and also from normal human immunoglobulin.3~NH2INH!2I - a - (Met) *His*Glu *Ala*Leu -His*Xsp -His *Tyr .Thr *Glu-Lys*Ser *Leu*Ser *Leu*Ser .Pro-Gly C0,HThe areas of variable sequence in the L- and H-chains constitute regionswhich need not be critical to a specialised function.The amino-acids in-volved could act simply as spacers between regions that contribute struc-turally to the antibody site. More plausibly, however, it is anticipated thatthe key to the nature of antibody specificity to widely differing antigens willbe found in those regions of the y-globulin molecule that possess a variableamino-acid sequence. Nothing is yet known at the molecular level of the wayin which amino-acid sequence may control antibody function. “ The rulesof protein stereochemistry are very complex and may not become apparentbefore the structures of maiiy proteins have been solved in atomic detail.’’ 39Pragmentation of y-globulin.The four-chain structure of y-globulin hasbeen broken down by a variety of methods to yield sub-units and fractions.Reduction of interchain disulphide bonds in the absence of urea with subse-quent exposure to acid 40, *l or urea l3 leads to dissociation of L-and H-chains;32 D. Givol and M . Sela, Biochemistry, 1964, 3, 451.33 R. L. Hill, personal communication.34 R. R. Porter and E. M . Press, Biochem. J., 1965, 97, 32P.35 D. Givol and R. R. Porter, Biochem. J., 1965, 97, 32C.36 E. Gross and B. Witkop, J . Biol. Chem., 1962, 237, 1856.37 E. M, Press, P. 5. Piggott, and R. R. Porter, Biochenz. J., 1966, in the press.38P. J. Piggott and E. M. Press, Biochem. J., 1966, in the press.39 M.F. Perutz, in “ Proteins and Nucleic Acids,” Elsevier Publishing Co., London,40 R. R. Porter, in “ Basic problems in Neoplastic Disease,” ed. A. Gellhorn and*l J. B. Fleischman, R. H. Pain, and R. R. Porter, Arch. Biochem. Biophys., 1962,1962, p. 59.E. Hirschberg, Columbia University Press, New York, 1962, p. 117.suppl. 1, 174494 BIOLOGICAL ClHEMISTRYneither treatment alone is sufficient. Separated L-chains dimerise and arecapable of forming an interchain disulphide bond.14 Mild reduction of y-glo-bulin followed by treatment with hydrochloric acid leads to separation ofthe L-H pairs as half mole~ules.~~ Hydrolysis with papain causes limitedoleavage of some peptide bonds in the H-chains;43 after reduction of thedisulphide bond between these chains,4* “ S ” and “B”’ fragments arereleased.Digestion with pepsin provides fragments similar to the S frag-ments coupled by a disulphide bond.44, 45 Finally, the selective cleavageof rabbit antibody by cyanogen bromide takes place at methionhe residuesapparently within the papain “Fragment I11 ” portion of the molecule,46and results in retention of the antibody activity. This is the first use of achemica’l reagent to fragment y-globulin which has not resulted in destruc-tion of the biological activity.*‘Fro. 3. Fragmentation of y-globdin.[Reproduced, with permission, from G. M. E d e h n and J. A. Gally, Proc. Ha€.Acad, Sci. U.S.A., 1964, 51, 846.3Antibody active site. The location of the antibody combining site, theactive centre in the y-globulin molecule that combines with antigen, has beenthe subject of many investigations. The active site appears to be presentprincipally on the H-chain of y-globulin ;20 separated L-chain does no$ appearto bind antigen.However, interaction of H-chains with L-chains is necessaryfor maximum expression of antibody activity.48~ 49 Furthermore, differencesin antibody specificity are reflected by changes in the electrophoretic beha-43 5. L. Palmer, A. Nisonoff, and K. E. Van Eolde, Proc. Nat. Acad. Sci. U.S.A.,1963, 50, 314.43 R. R. Porter, Biochem. J., 1959, 73, 119.44 A. Nisonoff, 0. Markus, and F. C. Wissler, Nature, 1961, 189, 293.46 R. J. Cahmann, R. Amon, and M. Sela, J. Biol. Chm., 1965, 240, PC2762.4 7 G. M. Edelman and J.A. Cally, Proc. Nat. Acad. Sci. U.S.A., 1964, 51, 846.48 G. M. Edelman, D. E. O h , J. A. Gally, and N. D. Zinder, Prm. Nat. Acad.S. Utsumi and F. Harush, Biochemistry, 1965, 4, 1766.Sci. U.S.A., 1963, 50, 753.F. Franek and R. S. Nezlin, FoZia Nicrobiol., 1963, 8, 128SMYTH: PROTEINS AND PEPTIDES 495viour of the L-chains,so and evidence has accumulated that portions of bothL- and H-chains are situated a t or near the antibody combining ~ite.~1-54Therefore the combining site for antigen in the y-globulin molecule appearsto be centred on the H-chain 2* but profoundly influenced by the L-chain.47For each of the L-H pair of chains in the y-globulin molecule there is onecombining site for antigen, and thus there are two combining sites permolecule of y-globulin; the precise structure of the active centres remains tobe elucidated.The specificity characteristics of the wide variety of antibodymolecules for different antigens appear to be based on the interaction betweena large number of L- and H-polypeptide chains of different amino-acidsequence.55, 66The molecular basis for complementarity between the structure of anantigen molecule and the specific amino-acid sequence of the correspondingantibody presents one of the most challenging problems in protein chemistry.Ribonuc1ease.-Bovine pancreatic ribonuclease (RNAase) continues to bewidely used in studies on the mechanism of enzyme action at the molecularlevel ; its established sequence and folded structure round the disulphidebridges form a complex steric molecule which is the basis for current investi-gations on the relation of structure to function.Reactions of monofunctional reagents with specific and defined groups inthe enzyme molecule are enabling deductions to be made on the functionalimportance of single amino-acid residues.The alkylation of ribonuclease bya series of unbranched cc- and #I-halogeno-acids of chain length 3 to 6 carbonatoms has been in~estigated.~~ As has been demonstrated previously in thereaction of iodoacetate with ribonuclease, substitution occurs either a timidazole nitrogen 3 of His-12 58 or a t imidazole nitrogen 1 of His-119.58, 59The rates of the reactions and the sites of alkylation were found to be defer-mined by the structural characteristics of the reagent, including chainlength, optical configuration, the presence of additional functional groups,and the position of the halogen relative to the carboxyl group.DL-CC-Bromocaproate (a), /I-bromopyruvate (b), and /?-bromopropionate (c) reactedexclusively a t His-119. The D-enantiomorphs of cc-bromopropionate anda-bromo-n-butyrate, on the other hand, reacted preferentially a t His-12.(a) Me*[CH,],*CHBr*CO,H(b) CH,Br*CO*CO,H(c) CH,Br *CH,*CO,HG. M. Edelman, €3. Benacerraf, Z. Ovary, and M. D. Poulik, Proc. Nut. Acad.Sci. U.S.A., 1961, 4'7, 1751.51D. A. Roholt, G. Radzimski, and D. Pressman, Science, 1963, 141, 726.52D. E. Olins and G. M. Edelman, J. Exp. Med., 1963, 116, 635.63F. Franek and R. 8. Nezlin, Biokhimiya, 1963, 28, 193.6c M.Metzger and S. J. Singer, Science, 1963, 142, 674.6s C. E. Buckley, P. L. Whitney, and C. Tanford, Proc. Nut. A d . Sci. U.S.A.,56 0. Smithies, Nature, 1963, 199, 1231.67 R. L. Henrikson, W. H. Stein, A. M. Crestfield, and S. Moore, J. Biol. Chem.,58 A. M. Crestfield, W. H. Stein, and S. Moore, J. BioE. Chern., 1963, 238,59E. A. Barnard and A. Ramel, Nature, 1962, 195, 243.1963, 50, 827.1965, 240, 2921.2421496 BIOLOGICAL CHEMISTRYFurther experiments from the same laboratory have strengthened the hypo-thesis that both histidine residues are involved in the active site of RNAase.58The interesting hybridization experiments which were noted briefly lastyear,6o in which aggregation of inactive derivatives of RNAase led to theformation of active molecules, have now been presented in full detaiLglThese specific reactions and interactions are a reflection of the intricatestereochemistry and conformation of the active site of the enzyme, but preciseinterpretation of the results must await further knowledge of the tertiarystructure.In a biologically active molecule where function resides in a, critical3-dimensional configuration, certain amino-acid residues may be far apartin the linear sequence yet closely positioned in the steric structure. Thedistance of separation of these residues may be estimated by cross-linkingwith a bifunctional reagent.The size of the reagent introduced, connectingthe two amino-acid residues in the protein, is a measure of the distance ofseparation of these residues in the active molecular structure, providingactivity is retained, Following an earlier application of 175-difluoro-2,4-dinitrobenzene in the cross-linking of insulin,62 the reaction of this reagentwith RNAase under conditions favouring the production of monomeric,intramolecularly cross-linked products has been studied.63 Three cross-linked derivatives of RNAase were obtained, and enzymatic activity was tosome extent retained in each.I n one of the products, a cross link had formedbetween the e-NH, groups of Lys-7 and Lys-41; this derivative was enzy-mically active.A product of the reaction of the monofunctional reagent fluorodinitro-benzene with RNAase is also a derivative in which the lysine residue atposition 41 is modified;64 the absence of activity in this product contrastswith the substantial activity of the cross-linked derivative, although bothcontain lysine a t position 41 blocked by similar substituents.However,with the monosubstituted product, there was evidence that after the blockingreaction, the molecule had undergone a conformational change which affectedthe accessibility of Lys-7 and distorted the anion binding site a t the activecentre; the cross-linked derivative may not be able to undergo such a change.The considerable enzymic activity of the cross-linked derivative precludesan important functional r81e for Lys-41 in the active site of RNAase, andestablishes a limiting spatial relationship between Lys-41 and Lys-7 thatis consistent with the expression of enzyme activity.The maximumdistance between the two a-carbon atoms of Lys-7 and Lys-41 was calculatedto be 17.2 A. This informsttion, together with the additional spatial datawhich will be obtained by identification of the other cross-linked derivatives,will provide valuable information for the construction of a 3-dimensionalmodel of the active enzyme. It will also provide data essential to answeringthe question of whether the structure which will be obtained by X-ray60 D. G. Smyth, Ann. Reports, 1964, 81, 507.61 R. G. Fruchter and A. M. Crestfield, J . Biol. Chem., 1965, 240, 3868; ibid., 3875.62 H. Zahn and J. Meienhofer, Malcromol. Chem., 1958, 26, 126.63 P. S. Marfey, H. Nowak, M. Uziel, and D. A. Yphantis, J .BWZ. Chem., 1965,64 C. H. W. Hirs, Brookhaven Syinposia in Biology, 1962, 1'01. XI', p. 154.240, 3264S N Y T H : PROTEINS AND PEPTIDES 497diffraction of the crystalline protein is the same steric structure as that pos-sessed by the active enzyme in solution.The difference in points of attack by a proteolytic enzyme on nativeRNAase compared with the denatured molecule has been used to provideinformation on the accessibility of certain residues in the 3-dimensionalstructure. In the native state, RNAsse, is resistant to digestion by trypsinand chymotrypsin, but after physical denaturation it becomes susceptiblet o attack.s5* 66 Mild treatment of native RNAase with subtilisin results in aspecific cleavage of the molecule, forming RNAase-S, without loss of enzymeactivity; only the peptide bond between Ala-20 and Ser-21 is split.67 Pepsinis capable of degrading RNAase to provide inactive products.The firstcleavage eliminates the C0,H-terminal tetrapeptide and results in someunfolding of the protein.68 The resulting molecule can be cleaved further bypepsin;GQ evidence was presented that the sites of attack were at the CO,Hgroups of Phe-120, Met-79, Thr-45, GluNH,-55, and Phe-8. The residualmolecule, held together by disulphide bonds, retained some conformation,because Tyr-25 in this material appeared to be unavailable for reaction withiodine. Carboxypeptidase attacks RNAase with reluctance, releasing amino-acids from the CO,H-terminus.Go, 70 Elastase cleaves the peptide bondbetween Ala-19 and Ala-20 and also that between Ala-20 and Ser-21, releas-ing free alanine and two polypeptide fragments, 1 to 19 and 21 to 124, whichbind strongly to each the product was designated RNAase-E, byanalogy with RNAase-S.As expected from the results of Richards and ofHofmann, KiNAase-E retained full enzymic activity.The ease of hydrolysis of the peptide bonds a t positions 19 and 20 indi-cates that Ala-19 and Ala-20 are on the outside of the molecule and arefreely available to certain enzymes. Since the 2 slanine residues are bor-dered by 7 serine or threonine residues, it seems likely that the hydroxy-amino-acid residues may play a special r81e in influencing the structure ofthe molecule. Hydroxyamino-acids appear to be capable of interactingwith each other in aqueous solvents. Poly-I;-serine, for example, is verysoluble in water, 'i2 and the dipeptide L-seryl-L-serine is only sparinglysoluble.73 It has been reported that hydroxyamino-acids exert disruptiveeffects on helices,'* and in synthetic polypeptides favour the formation ofp-structures and not helices.A tentative 3-dimensional structure of bovine pancreatic ribonucleasehas been proposed 75 (Figure 4). The model is based on the lineax sgquenceof amino-acid~,~~ data on the active site, interpretations of the results of ion6 5 J. A. Rupley and H. ,4. Sheraga, Biochemistry, 1963, 2, 421.6 6 T. Ooi, J. Rupley, H. A. Sheraga, Biochemistry, 1963, 2, 432.6 7 F. M. Richards and P. J. Vithayathil, J . Biol. Chem., 1959, 234, 1459.6 8 C.B. Anfinsen, J. Biol. Chem., 1956, 221, 405.69 H. Fujioka and H. A. Scheraga, Biochemistry, 1965, 4, 2197.70 J. T. Potts, D. M. Young, C. B. Anfinsen, and A. Sandoval, J. Biol. Chevn.,71 W. A. Klee, J. Biol. Chem., 1965, 240, 2900.72 Z. Bohak and E. Katchalski, Biochemistry, 1963, 2, 228.73 J. S. Fruton, J. BioE. Chem., 1942, 146, 463.7 4 J. C. Kendrew, Brookhaven Symposia in Biology, 1962, 15, 216.75 H. A. Saroff, J . Theoret. Biol., 1965, 9, 232.713 D. 0. Smyth, JTT. H. Stein, and S. Moore, J. Biol. Chem., 1963, 238, 227.1964, 239, 3781498 BIOLOGICAL CHEMISTRYnFIG. 4. IIEzlstrath of a proposed three-dimewional structure of ribonwkase.[Reproduced, with permission, from H. A. Saroff, J . Thoret. BWZ,, 1965, 9, 234.1FIG.5. Amim-acid sequence of bovine ribonuclease arranged to present 6 clustersgiving rise to proton and anion binding anomaties.[Reproduced, with permission, from D. G. Smyth, W. H. Stein, and S. Moore,J . Bwl. Chem., 1963, 238, 227.1binding, and on chemical evidence implicating the juxtaposition of certainamino-acid residues not closely related in the linear sequence (Figure 5).While many constraints have been included in the model, the structure isoutlined only approximately in certain areas. It may be noted that Lys-7is remote from Lys-41 in the model, although sound chemical evidence hasnow established their proximity.6s Until further chemical and physico-chemical data is available, the model should be considered as a workinghypothesisSMYTH: PROTEINS AND PEPTIDES 499The complete amino-acid sequence of Ribonuclease-TI (takdiastase)is now reported in full.77 The molecule consists of a single polypeptidechain of molecular weight 11,085, with 2 disulphide bridges (Figure 6).C p c c P C P p PI'1 1 1 1 1 2 13 14 i s 7 1 6 17 w 1 : o ; z o : 2 1 a n l a l i a s i n a1~ S c r ~ S ~ r ~ A s p ~ V r I ~ S c r ~ T h r - + A l r ~ C I n ~ A I r ~ ~ l a ~ C I ~ ~ T , r ~ C l n ~ L c r H i r C I uClr 31C T C C Thr 32I 1 ' I I 'Val ,jPC c..+Cir+GIn+Tyr + A s n + A s n t T ! .r + L ~ s + } i i s ~ P r o ~ T ~ r ~ S c r ~ A s n + S c f ~ l ~41 46 45 44 U 42 41 4 0 3 I n 36 3534'C P P P P*J Asn I 5 6 l j S 7 i S j 3 9 i G 4 61 6 2 7 0 44 (6 66p67S Asn t - + P r o ~ T j r - T j r ~ C I u ~ T T P ~ P r o ~ IIc .. L e u - * S c r - + S c r - . G l ? ~ A ~ ~ ~ ~ ~ ~ lt+ A GIy96 SerI T i s p pc53 n si w I) I n w 05 u tt aa a: DO r3 n n x 75 14 nFIG. 6. The amino acid sequence of ribonuclease T,.The points of hydrolysis by trypsin and chymotrypsin in the performic acid-oxidisedprotein and by pepsin in the heat-denatured protein are marked by T, C, and P, re-spectively. The solid lines represent extensive or rapid hydrolyses, and the dashedlines, incomplete or slower hydrolyses.[Reproduced, with permission, from K. Takahashi, J. Biol. Chem., 1965, 240, 4117.1The sequence was determined by the quantitative methods of Hirs,Moore, and Stein, including cleavage of the disulphide bonds by oxidationwith performic acid, and cleavage of the peptide chain by digestion withtrypsin, chymotrypsin, pepsin, subtfiin, and papain.The peptides wereseparated by chromotography on Dowex 1 -X2, Dowex-50x2, and diethy-laminoethyl cellulose, with volatile buffers as eluents. The amino-acidsequence of each purified peptide was determined by chemical and enzymaticmethods including dinitr op hen yla tion, Edman degradation, h y drazinol ysis ,and with the use of leucine aminopeptidase and carboxypeptidase.Trypsin caused cleavage at the carboxyl groups of Tyr-24, and Tyr-68,in addition to the expected sites at lysine and arginine. Trmtment of thetrypsin with diphenylcarbamyl chloride eliminated its chymotrypticactivity against synthetic substrates but did not appear to increase itsspecificity in attacking RNAase-TI.Chymotrypsin attacked peptide bondsinvolving the carboxyl groups of histidine, asparagine, leucine, alanine, andglutamine, in addition to the expected cleavages at tyrosine and phenyla-lanine; acidic residues adjacent t o the aromatic residues reduced the rates ofcleavage. Pepsin, papain, and subtilisin exhibited rather broad specificities.The structure of RNAase-T, (Figure 6) is of particular interest for thepurpose of comparison with that of pancreatic RNAase,'*, 95 the two enzymes77 K. Takahashi, J. Biol. Chern., 1965, 240, 4117.7 8 B. F. Erlanger and F. Edel, Biochemistry, 1964, 3, 347500 BIOLOGICAL CHEMISTRYperforming similar functions and differing in specificity. The amino-acidsequence of RNAase-T, (104 residues, 2 disulphide bridges) is found to betotally different from that of the pancreatic enzyme (124 residues, 4 disul-phide bridges).Takahashi 7 7 has suggested that similarities may exist inthe secondary and tertiary structures of the two enzyme molecules.MyogIobin.-The difficult amino-acid sequence of myoglobin has beenelucidated by Edmundson,l who used chemical methods. The completeprimary structure of the protein is illustrated in Figure 7 . Reaction of theprotein with iodoacetate 7 9 was exploited to advantage in overcoming theproblem of insolubility exhibited by the ‘’ core ” of tryptic peptides. Thereaction occurs a t all of the histidine residues, slightly a t the a-NH, groupof the terminal valine residue, and not a t all a t the E-NH, group of thelysine residues.The peptides obtained by digestion of the carboxymethy-lated protein with trypsin or chymotrypsin remained soluble, and weresuccessfully isolated in pure form. Trypsin and chymotrypsin caused cleav-age at sites in addition to those expected from their principal specificities.I n addition to this difficulty, some hydrolysis of the amides of glutamicacid and aspartic acid was noted for several peptides which were isolatedboth in acidic and in neutral forms. The size of the myoglobin molecule(153 residues), the fact that the protein possesses a single chain, the finding ofmultiple forms of peptides, and the occurrence of major problems withsolubility, combined to make the determination of this sequence a considerablefeat.The 3-dimensional structure of myoglobin in the crystalline state massolved in the outstanding experiments of Kendrew and his colleagues.80The amino-acid sequence presented above, established by chemical proce-dures, confirms and extends the results of current X-ray studies 81 in whichan atomic resolution of 1.5 A is being used to define unequivocal sequencesof amino-acids.In view of the difficulty in attaining this resolution withother crystalline proteins, it appears that determinations of amino-acidsequence will continue to be per€ormed by chemical methods and the se-quence thus obtained will be organised into a 3-dimensional structure byX-ray-crystallographic analysis. In this way a complete 3-dimensionalstructure of lysozyme has recently been elucidated in atomic detail by theX-ray-crystallographers a t the Royal Institution,82 the total amino-acidsequence having previously been established by chemical methods.83 Itshould be noted, however, that recent developments in the techniques ofX-ray diffraction have made it possible to detect the loss of as little as oneoxygen atom from oxymyoglobin, 84 the structure of the parent moleculebeing known at a resolution of less than 2 8.The new X-ray techniqueswere recommended for study of the interactions between proteins and small79 L. J. Banaszak, and F. R. N. Curd, J. BioE. Chem., 1964, 239, 1836.so J. C. Kendrew, R. E. Dickerson, B. E. Strandberg, R. G. Hart, D. R. Davies,D. C. Phillips, and V. C. Shore, Nature, 1960, 185, 422.s1 J.C. Kendrew, H. C. Watson, D. C. Phillips, and others, to be published.8a C. C. C. F. Blake, D. F. Koenig, G. A. Mair, A. C. T. North, D. C. Phillips, andV. R. Sam&, Nature, 1965, 206, 757.s8 R. E. Cenfield, J. BioE. Chem., 1963, 238, 2698.84C. L. Nobbs, H. C. Watson, and J. C. Kendrew, Nature, 1966, 209, 339r c p t i d c 3 - -- I------ -r132 I33 134 135 136 137 138 139 IM 141 142 143 I44 145 146 147 148 149 I50 $.Asn.Lys.Alo.Ltu.CIu.Leu.P~c.Arq,Lys.Asp,Ilc.Ala.Alo.Lys Tyr Lys.Glu.Lcu.Gly.Tyr 8 6 b 0I I 2 3 4 5 6 7 1 9 ;O I I I 2 I3 14 I S I6 17 16 19 2 0 21 22 23 24 25 26 2739 4 0 41 42 43 44 45 46 47 40 49 50 51 52 53 54 55P e p t i d r ?56 57 58 59 60 61 62 63 01 65 66 67 60 69 70 71 72 73 74 75 76 77 78 7 9 0 0 81 82.Lyi.Alaber~lu.AspL.u.Lyi.LyrHlr.GJ y.Val.Thr.Vol.Leu.Thr.Alo.Lcu G I y.Al0.11 r.bu.Lys Lya Lyi.GI y.HI s.HI r.Glu. b h b b8, 6 6 $ 6 g 694 9S 96 97 96 99 100101 102 103 0 4 105 lC% I07 IW 109 I10 I l l I12 113 114 115 116 I17 118 119 I2OIZIAla .Thr .kyr.Wls .Lye .I1 e .Pro .XI# .Lyr .Tyr .L.u.Clu .me .I I #.Sir .Glu Alo.11 c .I1 r.HI i .Pro.GI Q 6 6 6 602 BIOLOG TCAL CHEMISTRYmolecules, for example enzymes and coenzymes, provided suitable crystallinederivatives can be obtained.81, 85The binding of a fluorescent reagent by a nonpolar site in a protein opensthe possibility of obtaining information about regions in the molecule thatare not directly affected by the usual nucleophilic reagents. l-Anilino-8-napthalene sulphonate ( A N S ) binds stoicheiometrically to a specific site onapomyoglobin, but not to myoglobin itseKs3, Measurements of fluor-escence polarization and optical rotat'ory dispersion indicate that ANS com-bines a t the hydrophobic site occupied in myoglobin by hemin, and that theANS apomyoglobin complex exhibits a similar steric structure to nativemyoglobin.The reagent thus acts as a fluorescent probe for nonpolarbinding sites in proteins.Papain.-A previously reported sequence a t the NH,-terminus of papain 8 7has been corrected,SS, 89 and the suggestion that a large peptide fragmentcan be removed from the NH,-terminus without loss of the enzyme activityhas required re-examinati~n.~~ Error in the sequence work had arisen fromthe use of leucine aminopeptidase (LAP) which liberated amino-acids fromthe interior of the molecule, and from the use of the Edman degradationwith acetic acid-hydrochloric acid as the cyclizing agent.Both techniqueshad previously been shown to be suspect when applied in the determinationof the primary structure of ribonuclease, the misleading results obtainedNH,-Ileu-Pro-Glu-Tyr-Val-Asp -Trp-Arg-Gln-Lys-Gly- Ala-Val-Thr-Pro-Val-Lys-10Asn- Gln- Gly -Ser -Cys -G1 y -Ser -Cys-Trp/ /Ma-Phe // (Ileu) //Arg-Asn-Thr -Pro-20 30Tyr -Tyr -Glu-Gly -Val-Gln- Arg -Tyr -Cys - Arg- Ser - Arg - Glu-Lys-Gly -Pro -Tyr -Ala -40 50Ala-Lys-Thr-Asp-Gly-V~l-Arg-GIn-Val-G;ln-Pro-Tyr-A~~-Gln-Gly-Gly-Ala-Leu-Leu-Tyr -Ser-Ileu-Ala-Asn-Gln-Pro -Ser-Val-Val-Leu-Gln-Ala-&-Gly-Lys-Asp -Phe-Gln-Leu-Tyr-Arg-Gly-Gly-Ileu-Phe-Val-Gly-Pro-Cys-Gly-Asn-Lys-Val-Asp -His-Ala-Val- Ala - Ala -Val- G1 y -T yr - Asn -Pro -GI y -T yr -1leu -Leu-Ileu-Ly s - Asn- S er -Trp-Gly-Thr -Gly-Trp-Gly-Glu- Asp -GIp-Tyr-Ileu-Arg-Ileu-Lys-Thr-Gly-Asn-6070 8090 100110 120130Leu-Asn-Gh-Tyr -Ser-Glu-Gln-GIu-Leu-Leu-Bs~-Cys-Asp-Arg-Ar~-Ar~-Ser-Tyr -Gly -Cys -Tyr -Pro -Gly -Asp -G1 y -Trp / / Ser - Ala-Leu / /Val-Ala-Gln-Tyr -Gly -160 170Ileu-His-Tyr-Arg-Gly-Thr-Gly-,4sn-Ser -TUvr-Gly-Val-Cys-Gly-Leu-Tyr-Thr-Ser -140 150180 190Ser -Phe -Tyr -Pro -Val-Lys-Asn-CO,HFIG.8. Tentative amino-acid sequence of p a p a k 3Amino-acid residues placed in sequence are separated by dashes ; slant lines indicate-wiped peptides whose relative positions are not yet established.L.N. Johnson and D. C . Phillips, Nature, 1965, 206, 761.A. Light and E. L. Smith, J. Biol. Chem., 1960, 235, 3151.86L. Stryer, J. Mol. Biol., 1965, 13, 482.e8A. Light and J. Greenberg, J . Biol. Chem., 1965, 240, 258.89R. Frater, A. Light, and E. L. Smith, J. Biol. Chem., 1965, 240, 253SMYTH: PROTEINS AND PEPTIDES 503by these methods having necessitated a comprehensive re-investigation of theamino-acid sequence.76, 95The extensive studies currently reported on the structure of papainestablish firmly the almost complete amino-acid sequence (Figure 8).3, 8 * ,The disulphide bridges have been located between cystine residues a t posi-tions 22 and 159,43 and 152, and lOOand 186. The remaining single cysteine,curiously, is liberated only after reduction of the protein and appears to bedirectjly involved in the activity of the enzyme.Similar findings have beenreported in a detailed study of Streptococcal proteinase: a single reactivesulphydryl group again was liberated only after reduction of the precursorprotein. The amino-acid sequence of a large peptide containing the SH-groupwas identified. 91By designing an inhibitor related structurally to a specific substrate ofpapain and by inserting into the inhibitor a, reactive site with an affinity forSH-groups, inhibition of the enzyme might be accomplished and simul-taneously the active cysteine residue become specifically modified. Reactionof reduced papain with two equivalents of the chloroketone (I), related toN-tosylglycine methyl ester, resulted in inhibition of the papain activity andenabled identification of Cys-25 as the reactive cysteine a t the active site.92Enzymic hydrolysis of the peptide containing the modified cysteine residueled to its isolation as a dihydro-1,4-thiazine derivative (11).CHJCI S/ \CH 'CH2II IC CH*CO,H\ /A similar heterocyclic structure is formed when the addition product ofcysteine and N-ethylmaleimide (NEM) is exposed to neutral or alkalineCOlH CO,HI II - oc s0 - C ? ,s \ IOC-CH2 I /=, H HOIC - CHINC' Hcondition^,^^ the a-NH, group of the cysteine adduct undergoing infra-molecular cyclization with a ketonic group of the succinimide ring.Cytochrome C.-The complete amino-acid sequence of hog heart cyto-chrome C (104 residues) has been determined,94 and may be compared withDo J.R. Kimmel, H. J. Rogers, and E. L. Smith, J . BWZ. Chem., 1965, 240, 266.Dl T. Y. Liu, W. H. Stein, S. Moorey and S. D. Elliott, J. BWZ. Chem., 1965, 240,*3 D. G. Smyth, A. Nagamatsu, and J. S. h t o n , J . Amer. Chm. Soc., 1960, 82,D4 J. W. Stewart and E. Margoliash, C a d . J. Hochem., 1965, 43, 1187.1143; T. Y. Liu and S. D. Elliott, Ndure, 1965, 208, 33.4600.S. H. Hussain and G. Lowe, Chern. C o r n . , 1965, 345504 BIOLOGICAL CHEMISTRYthat of cytochrome C from other species (noted in reference 95). A strikingcorrespondence exists between hog protein, the horse protein, and the humanprotein. In the sequences of the hog and the human protein, only threeamino-acids differ, the human protein possessing threonine a t Ser-47 ,glycine at Lys-60, and glycine at Thr-89 (see Figure 9, in which an asteriskAcetyl-Gly -Asp -Val-Glu-Lys-Gly -L ys-Lys- Ileu -Phe -Val+ -GluNH, + -Lys -CyS-Ah+-GluNH,-CyS -His-Thr-Val-Glu-Lys-Gly-Gly-Lys-His-Lys-Thr-Gly-10I I 20Pro -AspNH,-Leu-His-Gly-Leu-Phe-Gly-Arg-Lys-Thr-Gly-GIuNH,-Ala-Pro -30 40Gly -Phe* -Ser *-T yr -Thr -Asp f -Ah-AspNH,-Lys - AspNH, -Lp- Gly- Ileu-Thr + -Try-Gly*-Glu-Glu+-Thr-Leu-Met-Glu-Tyr-Leu-Glu-AspNH,-Pro-~ys-L~s-5060 70Tyr -1leu -Pro -Gly -Thr -Lys-Met -1leu -Phe -Ah+ - Gly -1leu -Lys-Lys -Lys -Gly * 9 i- -80Glu-A rg -Glu+ -Asp -L eu-Ileu-Ala-Tyr-Leu -Lys-Lys-Ala-Thr-AspNH,-GluC0,H90 100 104FIG. 9.Amino-acid sequence of hog heart cgtochrome C.95The basic residues are in italics, and the hydrophobic residues are in bold-facedtype.Residues marked with an asterisk are those that vary from residues in correspond-ing positions in the horse heart protein. Residues marked with a + sign differfrom the corresponding amino-acids in human cytochrome.denotes residues varying from those in corresponding positions in horseheart protein,96 and a + sign those differing from the corresponding amino-acids in human cytochrome 9 7 ) . These findings extend the pioneer experi-ments of Tuppy and his colleagues 98, Q9 which revealed that the functionalheme peptide in hog heart cytochrome C is identical to that in the horse andbeef proteins. The high degree of correspondence exhibited by cytochromeC from species widely differing in the evolutionary scale indicates that theproteins derive as the product of a single gene which has become modifiedonly slightly during development (see Table 1, ref.95). In this connexion itmay be noted that cytochrome C isolated from the hearts of the EasternDiamond Back rattlesnake ‘‘ Grotalus adamanteus ” possesses a very similarsequence to that of homologous vertebrate proteins.lO0 In addition to thespecies similarities exhibited by cytochrome C, cytochrome proteins isolatedin good yield from brain, kidney, liver, and skeletal muscle exhibit an iden-tical amino-acid sequence, g4 despite the wide differences in embryologicalorigin and function of these tissues.l*l The biosynthesis of cytochrome Cin the various tissues of a single species may therefore be considered to becontrolled by a single structural gene.The search for specific amino-acid residues involved in co-ordination of95D.G. Smyth, Ann. Reports, 1963, 60, 468.96 E. Margoliash, E. L. Smith, G. Kreil, and H. Tuppy, Nature, 1961, 192, 1125.97 H. Matsubara and E. L. Smith, J. Biol. Chem., 1963, 238, 2732.98 H. Tuppy and G. Bodo, Monatsh., 1954, 85, 1182.99 S . Paleus and H. Tuppy, Acta Chern. Xcand., 1959, 13, 641.l o o Om. P. Bahl and“E. L. Smith, J. BkE. Chem., 1965, 240, 3585.101 A. H. Leninger, The Mitochondrion,” Benjamin, Inc., New York, 1964SMYTH: PROTEINS AND PEPTIDES 505the iron atom in cytochrome C has been narrowed. The classical view is thatco-ordination occurs through the imidazole nitrogen of two histidine resi-dues.102 However, some evidence was obtained that the ligands in questionwere an imidazole group and the E-NH, group of a lysine residue; firstLys-13 (ref. 103) and then Lys-25 (ref.104) was implicated. It has nowbeen found that all of the lysine residues in cytochrome C can be guanidinatedwithout significant change in structure, and with complete retention of thea~tivity.10~ An involvement of lysine in one of the co-ordination positionsa,bout the heme iron of cytochrome C is therefore precluded.The problems involved in relating the function of a protein to its struc-ture are increased when the protein is capable of existing in a number offorms that retain activity. The usual preparative methods for cytochrome Cresult in the isolation of polymerised material, in addition to the monomericmolecule;106 the polymeric forms exhibit substantial, though reduced,electron transfer activity compared with the monomer. The monomer itselfappears to have two alternative configurations in alkaline solution,lO7 andthese can be distinguished by their ability to react with reducing agents.Multiple forms exist also in yeast cytochrome C lo8 but in this case the freesulphydryl group of a cysteine residue participates in dimer formation in amanner similar to the formation of dimers from monomers of Bence- Jonesprotein.Peptide hormones.-In view of the great interest in structure-functionrelationships among polypeptides, the development of rapid methods ofpeptide synthesis has assumed considerable importance.The method ofsolid-phase peptide synthesis,10g which involves stepwise assembly of thepeptide chain anchored covalently at one end to an insoluble particle, hasbeen adapted for performance by an automatic machine;llO the total syn-thesis of bradykinin (9-residues) was achieved in 32 hours. An alternativemethod has been presented in which the peptide is synthesised on a polymericsupport not in the solid phase but in solution.ll1 The resin employed waspolystyrene substituted by chloromethylation to provide attachment sitesfor the peptide. Since this resin is soluble in organic solvents and insolublein water, the whole range of synthetic techniques currently used in the fieldcan be applied to the resin-bound peptide, while removal of excess reactantsand side products is facilitated simply by precipitation in aqueous medium.High-molecular-weight carriers have been elegantly employed in thesynthesis of cyclic peptides.ll2 The NH,-protected peptide is coupled throughlo* H.Theorell, J . Amer. Chem. SOC., 1941, 63, 1820.loa E. Margoliash, N. Frohwirt, and E. Weiner, Biochem. J., 1959, 71, 559.lo* E. Margoliash, in Enzyme models and Enzyme Structure, Brookhaven Symposialo6 T. P. Hettinger and H. A. Harbury, Proc. Nat. Acad. Sci. U.S.A., 1964,52,1469.lot) E. Margoliash and J. Lustgarten, J . BioZ. Chem., 1962, 237, 3397.lo' C. Greenwood and G. Palmer, J . Biol. Chern., 1965, 240, 3660.lo* K. Motonaga, E. Misuka, E. Nakajima, S. Veda, and K.Nakanishi, J . Biochem.loS R. B. Merrifield, J . Amer. Chena. Soc., 1963, 85, 2149.110 R. B. Merrifield and J. M. Stewart, Nature, 1965, 207, 522.ll1 M. M. Shemyakin, Yu, A. Ovchinnikov, A. A. Kinyushkin, and I. V. Kozhevni-112 M. Fridkin, -4. Patchornik, and E. Katchalski, J . Anzer. Chem. SOC., 1965, 87,in Biology, 1962, No. 15, p. 266.(Japan), 1965, 57, 22.kova, Tetrahedron Letters, 1965, 2323.4646.506 BIOLOGICAL CHEMISTRYQ N 0 2?p Pc=oINHZI OH 0IC=G y C = OI IPe2 0 PepI r w : AHits C0,K-group to the OH-group of poly-4-hydroxy-3-nitrostyrene, or to theOH-group of a branched copolymer of DL-lysine and 3-nitro-~-tyrosine.The intramolecular acylation reaction takes place in good yield, liberatingthe anticipated products. It should be noted that previous methods, whichinvolve cyclization a t high dilution, have provided cyclic peptides onlyin poor yield.The total synthesis of the A- and B-chains of insulin by the classicalmethods of peptide synthesis, reported last year (cf.ref. 60), has now beendescribed in full detail,l13 though the problem of correctly coupling the disul-phide bridges remains to be solved. An important advance has been madeby Zervas and his colleagues,114 who have successfully synthesized a frag-ment of the A-chain containing the intrachain disulphide bridge. Theremaining difficulty of correctly coupling the interchain disulphide bridgesmay be overcome by an adaptation of the peptide cyclization methodpresented by the Weizmann Institute group.l12 Further recent achieve-ments in the field of peptide synthesis include the total synthesis of the S-peptide (20 residues) of ribonuclease l l .5 and the synthesis of the fragments ofglucagon (29 residues) .l16Angiotemh-The availability of a specific antibody directed against apeptide of small size and known amino-acid sequence should facilitate studieson the structure of antibody y-globulin and lead to an understanding of theexact requirements and relationships of antigenic determinants in the peptidemolecule. Angiotensin has been coupled through its terminal NH 2-group,and also through its terminal C02H-group, to poly-I;-Iysine (Figure 10) ;l17both polymers were effective in eliciting the production of antibody withconsiderable affinity for angiotensin. The specificity of the binding wasllS H. Zahn, H. Bremer, W. Svoka, and J. Meienhofer, 2. Naturforsch., 1965, 20b,646; R. Zabel and H. Zahn, ibid., p. 650; H. Zahn, H. Bremer, and R. Zabel, iM.,p. 653; J. Mcienhofer and E. Schnebel, ibid., p. 661 ; H. Zahn, 0. Brinkhoff, J. Meienhofer,E. F. Pfeiffer, H. Ditschunett, and C. Gloxhuber, ibid., p. 666; Niu Chin-i, Kung Yueh-ting, Huang Wei-teh, Ke Lin-tsung, Chen Chan-chin, Chen Yuan-chug, Du Yu-cang,Jiang Rong-qing, Tsuo Chen-lu, Hu Shih-chuan, Chu Shang-quan, and Wang Keh-zhen, Sci. Sinica, 1965,14, 1386; Wang-Yu, Hsu Je-Zen, Loh Jen-yung, Huang Hang,and Huang Jing-jian, ibid., p. 1284.114 K. Zervas, I. Photaki, A. Cosrnatos, and D. Borovas, J. Amer. Chem. SOC., 1965,87, 4922.116 K. Hofmann, R. Schmiechen, R. D. Wells, V. Wolman, and Yanaihara (positions1-7); and other references, J . Amer. Chem. SOC., 1965, 87, 611.1l8 E. Wunsch and A. Zwick, Chem. Ber., 1964, 97, 2497; ibid., pp. 3298, 3305,3312; E. Wunsch and G. Wendelberger, ibid., p. 2504; E. Wunsch, F. Drees, and J.Jentsch, Chem. Ber., 1965, 98, 797, 803; K. Lubke and E. Schroder, Annalen, 1966,681, 231, 241, 250; E. Schroder, ibid., 1965, 088, 250.117 E. Haber, L. B. Page, and G. A. Jacoby, Biochemistry, 1965, 4, 693SMYTH: PROTEINS AND PEPTIDESI I[Lys-NHd,,I Lys-N-C-Phe-Pro-H is-Val-Tyr-Val-Arg-Asp-NH2I NH? 1 A&[Lys-NH?),I Lys-N-C-Phe-Pro-His-Val-Tyr-Val-Arg-Asp-NH2; I l l Ii H O NH2- A-(Phe)-PL507[tys-NH& 0Lys-N-C-N-C-CsH 4-C-N-C-NH-Asp-Arg-VaI-Tyr-VaI-His-Pro-Phe-C I HOHH2 H:HOI 0I // Lys-N-C-N-C-C~HcC-N-C-NH-Asp-Arg-Val-Tyr-Va1-His-Pro-Phe-Ci I I I I I I 1 llI //NH2 1 ‘OHNH2 1 ‘OHI l l 1 1 I I IIILys-NH&: H O H H a HcHOPL-(Am)-AFIG. 10. Schematic representation of angktensin poly-~-lysine wpolymers.[Reproduced, with permission, from E. Haber, L. B. Page, and G. A. Jacoby,Biochemistry, 1965, 4, 693.1demonstrated by displacement of 14C-labelled angiotensin from the antibodyby unlabelled angiotensin and by the inability of excess of bradykinin,vasopressin, and other peptides to compete in the binding process. Thus,although itself incapable of eliciting antibody formation, angiotensin iscapable of binding to an antibody produced to an angiotensin polymer. Thespecificity and the high affinity of the binding between angiotensin and theantiserum recommend an application of this peptideprotein interaction inan immuno-assay of the hormone.The polymer containing angiotensin coupled through its NH,-group wasreported to exhibit no biological activity, whereas the polymer coupledthrough the angiotensin C0,H-group retained substantial bioactivity.These findings in both cases codict with the currently held views on theimportance of these groups in the activity of the hormone. Furthermore,the C0,H-coupled angiotensin polymer exerted the same biological activityon smooth muscle when tested in the presence or absence of its specscantiserum. The affinity exhibited by the angiotensin polymer for its anti-body, though high, must be considerably less than its affinity for the physio-logical receptor. It may be noted that antibodies formed against extendedangiotensin and bradykinin molecules have been reported from two otherlaboratories; 118, 119 in these cases the carrier protein was itself antigenic andthe precise points of attachment between the peptide and the carrier proteinwere not determined.118 S. D. Deodhax, J. E x p Med., 1960, 111, 429.T. L. Goodfriend, L. Levine, and G. D. Fasman, Science, 1964, 144, 344508 BIOLOGICAL CHEMISTRYBrabkinh-The peptide hormone, bradykinin, is derived physiologicallyas a fragment of an inactive precursor polypeptide. It is therefore to beexpected that the coupling of amino-acids to the NH,-terminus of bradg-kinin, by peptide synthesis, would result in the formation of inactive or lessactive analogues. Thus, the naturally occurring hendecapeptide, methionyl-lysylbradykinin, exhibits one third of the activity of bradykinin,120 and thisMet *Lys.Arg*Pro*Pro*Gly*Phe-Ser *Pro*Phe*Argpeptide with t-butyloxycarbonyl blocking substituents attached at thefree NH,-groups possesses 1/150th the activity of bradykinin.121 Similarly,the addition of one oxygen atom to Met. Lys- Bradykinin, forming the sul-phoxide, was without effect on bioactivity, whereas the addition of twooxygen atoms, forming the sulphone, resulted in a 10-fold reduction inactivity.121There have been two reports on the isolation of almost pure brady-kininogen,122, 123 the precursor protein from which bradykinin is released byenzyme action in serum. Difficulty was encountered because smooth musclecontracting substances, presumably bradykinin and its relatives, werereleased during the purification procedure and severely depleted the yieldof bradykininogen. Perfunctory evidence was presented that trypsin andvenom enzyme acted on bradykininogen to release bradykinin, whereas hogpancreatic kallikrein released lysylbradykinin ( kallidin).124 A polypeptideinhibitor of kallikrein has recently been isolated from bovine lung. Theestablishment of its amino-acid sequence (58 residues) 124 (see Figure 11)revealed that its structure is identical with that of trypsin inhibitor fromborine p a n ~ r e a s . ~ ~ ~ - l ~ 'NH,Arg-Pro *Asp*Phe*Cys*Leu*Glu *Pro *Pro *Tyr *Thr*Gly -Pro *Cys *Lys *Ala*Arg*30NH220 ITleu.Ileu*Arg*Tyr*Phe*Tyr.Asp*Ala*Lys*Ala,*Gly*Leu*Cys *Glu *Thr -Phe-50H,N NH, NH240 I 1 IVal*Tyr *Gly -Gly*Cys -Arg*Ala*Lys *Arg *Asp 'Asp *Phe *Lys *Ser *Ala-Glu *AspCys-Met *Arg*Thr *Cys *Gfy *Gly *Ala.CO,H58FIG. 1 I. Amino-acid sequence of EaEliErein inhibitor from bovine120 D. F. Elliott and G. P. Lewis, Biochem. J . , 1965, 95, 437.121 V. Uhlinger, Experientia, 1965, 21, 271.lZ2 E. Habermam, W. Klett, and G. Rosenbusch, 2. physiol. Chem., 1963, 322,123 T. Suzuki, Y. Mizushima, T. Sato, and S. Iwanago, J . Biochem. (Japan), 1965,124 F. A. Anderer, 2. Naturforsch., 1965, 206, 462; ibid., p. 499.125 J. Chauvet, G. Nouvel, and R. Acher, Biochim. Biophys. Acta, 1964, 92, 200.lZ6 B. Kaasell, M. Radicevic, 31. J. Ansfield, and M. Laskowski, Biochem. Biophys.1 2 7 V. Dlouha, D. Popsilova, B. Meloun, and F. Sorrn, CoZZ. Czech. Chem. Comm.,121.57, 14.Res. Comm., 1965, 18, 255.1965, 30, 1311SMYTH: PROTEINS AND PEPTIDES 509This finding adds doubt to the current view that certain serum enzymes,such as kallikrein, bradykininase, and angiotensinase, are characteristicproteins with the specific functlion implicit in their titles. It seems probablethat these enzymes are in fact trypsin, carboxypeptidase, and leucineaminopeptidase, which exert their proteolytic activities against a broadspectrum of substrates.p-Lipotropic Hormone.-Several polypeptides have been demonstratedto possess in vitro lipotropic activity. These include growth, adrenocor cico-trophic, and a- and P-melanocyte-stimulating hormones. An additionallipotropic peptide has now been isolated from sheep pituitary glands, andits complete amino-acid sequence has been determined 8 (Figure 12).NH2IKH ,-Glu-Leu-Gly-Thr-G1u-Arg-Leu-Glu-Glu-Ala-Arg-Gly-Pro-Glu-Ala-1 2 3 4 5 6 7 8 9 1 0 1 1 1 2 1 3 1 4 1 5Ala-Glu-Glu-Ser-Ala-Ala-Ala-Ala-Arg-Ala-Gl~~-Leu-Glu-Tyr-Gly-Leu-Val-1G 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31NH,IAla-Glu-~~Glu-Ala-Ala-Glu-Lys-Lys-~p-Ser-Gly-Pro-T~-Lys-Met -32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47Glu-His-Phe-Arg-Try-Gly-Ser-Pro-Pro-Lys-Asp-Lys-~g-Tyr-Gly-Gly-45 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63NH,IPhe-~~et-Thr-Ser-Glu-Lys-Ser-Glu-Thr-Pro-Leu-Val-Thr-Leu-Phe-Lys-64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79NH2 NH2 NH2I 1 IAsp-Ala-Ileu-Lys-Lys-Asp-His-Ala-Lys-Gly-Glu-CO,H80 81 82 83 84 85 86 87 88 89 90FIG. 12. The antino-acid sequence of the sheep pituitarJ fi-LPH.aThe sequence Met*Glu*His*Phe*Arg*Try*Gly* is common to ACTH andMSH peptides from a variety of species; the sequence 37-58 in @-LPH isidentical t o that of human a-MSH except that Ser-42 and Lys-46 are re-placed by Glu and Arg respectively in the human hormone

ISSN:0365-6217    

DOI:10.1039/AR9656200427

出版商:RSC    

年代:1965

数据来源: RSC

摘要:

ANALYTICAL CHEMISTRYJ. B. Headridge, T. B. Pierce, and D. M. W. Anderson( J . B. H.: Department of Chemistry, The University, S b m , 10; T. B. P.:Analytical Chemistry Group, A.E.R.E., Harwell; and D. M . W. A,: Department ofChemistry, University of Edinburgh, Edinburgh, 9)1. Introduction.-A most interesting paper on trends in analyticalchemistry in 1965 has been published, these being compared with trends in1946 and 1955.’ The following statement is from that article: “ I n broadcategories, the methods of analysis most commonly encountered in currentpublications are, in descending order, optical absorption and emission,titrimetry, gas analysis (including gas chromatography), electrical methods,radioactivity, gravirnetric methods, and X-ray methods.”One in seventeen of all papers abstracted in Chemical Abstracts 1965 awas on analytical chemistry, the number of abstracts on analytical chemistrybeing about 10,OOO.l Russia, Germany, the United States, Britain, andJapan have, in the last ten years, increased their output of papers on analy-tical chemistry by factors of approximately 4.8, 2-0, 1.7, 1.2, and 1.1 re-spectively.1In 1965, the trend towards the increased use of instrumental methods ofanalysis has continued.There is even greater interest than in 1964 in spectro-scopic methods of analysis and in electrochemical methods, particularlypolarography, voltammetry, and coulometry. Atomic absorption spectro-scopy and spectrofluorjmetry are continuing to receive attention from anincreasing number of analytical chemists.The research effort given to gravimetric methods of analysis is stiUdecreasing, as expected, but solvent extraction as a method of separationbefore solution spectrophotometric, atomic absorption spectrophotometric,and polarographic analysis, is receiving increasing attention.A very largenumber of papers on gas-phase chromatography continue to appear.2. Qualitative Analysis.-Chalmers and Dick have continued to developanalysis schemes based on combinations of solvent-extraction and spectro-photometry; Lyle and Shendrikar have described * the separation of gallium,indium, thallium, germanium, tin, and lead by solvent extraction withN-benzoyl- AT- phenylhydroxylamine .There have been other novel and interesting approaches.The separationand identification of Group I, 11, and IV cations by thin-layer chroma-tography on maize starch has been de~eloped,~ and a similar technique,using circular thin-layer chromatography,6 gives very rapid identification ofgroup I-V cations after group separation has been effected by classicalR. B. Fischer, Anulyt. Chern., 1965, 37, No. 13, 27A.R. A. Chalmers and D. M. Dick, AnuZyt. Chim. Ada, 1965, 32, 117.S. J. Lyle and A. D. Shendrikar, Analyt. Chim. Ada, 1965, 32, 576.M. H. Hashmi, M. A. Shahid, and A. A. Ayaz, Talanta, 1985, 12, 713.a Chern. Abs., 1965, 62 and 63.ti V. D. Canic and S. M. Petrovic, 2. analyt. Chem., 1966, 211, 321; V. D. Canic,S. M. Petrovic, and A. K. Bern, ibid., 1965, 213, 251512 ANALYTICAL CHEMISTRYprocedures.Ottendorfer has devised a method of combining the ring-oven with thin-layer chromatography, and a " slotted oven " for the identifi-cation of anions has been described.8" Co-ordination chain reactions " have been proposed for the examina-tion of ultra-trace quantities of cations that complex with EDTA ; extensionsof this sensitive technique t o other complexing systems seem feasible.Further developments are also likely to arise from the appIication10 ofcatalytic reactions to indicate end-points in titrimetric processes, and fromthe characterisation of some organic compounds by their self-emitted infra-red radiation.llFour novel methods of gas analysis have been proposed: Luis and SB 12have developed simple ultramicro- techniques using a stereoscopic micro-scope; Williams and Findeis l3 have developed " Geiger pulse attenuation ;"and detectors based on (a) electronic emission spectra of organic vapours 1.1and ( b ) the energy required to produce an ion-pair in a vapour ls have beendescribed.An important approach to the concentration of trace elements, offeringscope for development, is based on " precipitation ion-exchange :" thematrix and trace elements are adsorbed on a cation-exchange column, thenthe eluent precipitates the matrix and elutes the traces.16Separations of anions have been based on the use of cadmium acetate 1 7and silver chromate-impregnated paper.ls Freiser et al.19 have foundarylazo-8-quinolinols to form metal chelates at low pH values.The ana,ly-tical uses of compounds containing P=S and P(S)SH groups have beenreviewed,20 and Few 21 has described the colorimetric reactions of steroidswith perchloric acid and aromatic aldehydes.Enzymic analysis will become increasingly important in the future :Bergmeyer z2 has reviewed recent developments, and a technique for main-taining the activity of enzyme preparations has been described.233.Methods of Separation.--Solvent extraction. Details of an automatedthree-phase countercurrent apparatus have been p~blished,~4 and computer7 L. J. Ottendorfer, Analyt. Chim. Acta, 1965, 33, 115.8 M. A. Leonard, S. A. E. F. Shahine, and C. L. Wilson, Mikrochim. Ichnoanalyt.Acta, 1965, 160.D. W. Margerum and R. K. Steinhaus, Analyt. Chenz., 1965, 37, 222.lo H.Weivz and U. Muschelknautz, 8. analyt. Chem., 1965, 215, 17.lIM. J. D. Low, L. Abrams, and I. Coleman, Chenz. Comm., 1965, 389.l2 P. Luis and A. Sh, MikTochim. Ichnoanalyt. Acta, 1965, 621.l3 F. W. Williams and A. F. Findeis, Analyt. Chem., 1965, 37, 857.l4 A. J. McCormack, S. C. Tong, and W. D. Cooke, Analyt. Chem., 1965, 37,l6 J. E. Lovelock, Analyt. Chem., 1965, 37, 583.l8 F. Tera, R. R. Ruch, and G. H. Morrison, Analyt. Chem., 1965, 37, 358; R. R.l7 I. K. Taimni and R. Rakshpal, J . prukt. Chem., 1965, 25, 134.lo 5. Takamoto, Q. Fernando, and H. Freiser, AnaZyt. Chem., 1965, 37, 1249.2o T. H. Handley, TaZanta, 1965, 12, 893.21 J. D. Few, Analyst, 1965, 90, 134.22 H. M. Bergmeyer, 2. analyt. Chem., 1965, 212, 77.23 E. K. Baurnan, L.H. Goodson, G. G. Guilbault, and D. N. Kramer, Analyt.24 H. L. Meltzer, J. Buchler, and Z. Frank, Amzlyt. Chem., 1965, 87, 721.1470.Ruch, F. Tera, and G. H. Morrison, ibid., p. 1565.J. G. Sabo, Chemist-Analyst, 1965, 54, 110.Chem., 1965, 37, 1378J . B . HEADRIDGE, T . B . PIERCE, D . M . w. AXDERSOX 513techniques have been applied 25 in solvent extraction studies involvingtantalum fluoride with isobutyl ketone, N - benzoyl-N-phenylhydroxylamine,or tri-n-octylphosphine oxide. The latter reagent was also used in the deter-mination of zirconium and hafnium in niobium.26 Applications of tri-n-octylphosphine sulphide have also been investigated,z7 and Handley 28 hasused metal di-n-butylphosphorodithioates as solvent extractants. N -Benzoyl-N-phenylhydroxylamine 25 was also used by Lyle and Shendrikar 29in studies with protactinium.Stephen and Townshend 30 have studied the reactions of rhodaminederivatives with many metals, with special reference to the production ofsoluble complexes.Trifluoroacetylacetone has been used in conjunctiouwith ben~ene,~1 chl~roform,~~ or chloroform and isobutylamine 33 for theextraction of widely differing mixtures of cations.Other investigators have studied the separation of molybdenum( VI)from rhenium( N) with pentyl a~etate,~4 and of selenium from telluriumwith ethyl methyl ketone.35 Systematic studies of solvent mixtures for theseparation of the alkaline earths 36 and for the extraction of zinc oxinate 37have been published. Moore 38 has made an extensive investigation of theextraction of actinides and lanthanides, from aqueous solutions of a varietyof organic acids, with high-molecular-weight amines.Other extensivestudies have involved the extraction of palladium and rhodium,39 and thedistribution 40 of 45 elements between 83 yo 2-ethylhexanol-17 yo lightpetroleum and hydrochloric acid of different concentrations. Brooks 4 l hasproposed new techniques, based on liquid-liquid, discontinuous solventextraction, for the determination of trace elements in silicate rocks and insea water; enrichment factors of 400,000 are claimed.Applications of this convenient techniquecontinue to increase ; devices facilitating continuous-flow systems continueto be publi~hed,4~ and methods for increasing reproducibility 43 and pre-venting adsorbent loss 44 have been recommended.Thin-layer chromtttography.25 L.P. Varga, W. D. Wakley, L. S. Nicolson, M. L. Madden, and J. Patterson,seD. F. Wood and J. T. Jones, Analyst, 1965, 90, 125.27 D. E. Elliott and C. V. Banks, Analyt. Chim Acta, 1965, 33, 237.28 T. H. Handley, Analyt. Chem., 1965, 37, 311.2B S. J. Lyle and A. D. Shendrikar, Talanta, 1965, 12, 553.30 W. I. Stephen and A. Townshend, Analyt. Chim. Acta, 1965, 33, 257.31 G. P. Morie and T. R. Sweet, Analyt. Chem., 1965, 37, 1552.32 W. G. Scribner, W. J. Treat, J. D. Weis, and R. W. Moshier, Analyt. C'hetn.,33 W. G. Scribner and A. If. Kotecki, Analyt. Chem., 1965, 37, 1304.34V. Yatirajam and R. Prosad, Indian J . Chem., 1965, 3, 345.35 N.Jordanov and L. Futekov, Talanta, 1965, 12, 371.37 G. K. Schweitzer, R. B. Neel, and F. R. Clifford, Analyt. Chim. Acta, 1965, 33,38 F. L. Moore, Aizalyt. Chem., 1965, 3'7, 1235.39 H. C. Eshelman, J. Dyer, and J. Armentor, Analyt. Chim. Acta, 1965, 32, 411.*O K. A. Orlandini, M. A. Wahlgren, and J. Barclay, Analyt. Chem., 1965,37, 1148.O1 R. R. Brooks, Talanta, 1965, 12, 505 and 511.4 2 T. M. Lees, M. J. Lynch, and F. R. Mosher, J . C'lwontatog., 1965, 18, 595.4 3 L. X. Bark, R. J. T. Graham, and D. McCormick, Talanta, 1965, 12, 122.4 4 31. P. Clapp and J. Jeter, J . Chronzatog., 1965, 17, 558.Analyt. Chem., 1965, 37, 1003.1966, 37, 1136.E. Gagliardi and W. Likussar, Milerochim. Ichnoanalyt. Acta, 1965, 765.514514 ANALYTICAL CHEMISTRYOf the papers dealing with inorganic 45 applications, reference is restrictedhere to the separation of phosphates 46 on circular layers of corn starch, andto the separation of halides 47 and noble metal rhodizonates 48 on silica gel.A larger number of interesting papers were devoted to organic problems.Iodine-quenched fluorescence 49 offers a sensitive method of detection, andspectral reflectance 50 has been recommended for the estimation of amino-acids.Other investigators have studied the separation of ester~,~1 long-chaintertiary a m i n e ~ , ~ ~ quinones 53 on polyamide layers, terpene and sesquiterpenealcohols on silica gel impregnated with silver nitrate,54 and chlorophyll com-ponents on powdered sugar containing 3 yo starch.55 Acridones and phenan-thridones have been separated, and located 56 by fluorescence methodsemploying trifluoroacetic acid fumes and tetraethylammonium hydroxidesolution.Carbohydrate chemists 57, 58 have made extensive use of thin-layertechniques. Roudier 59 has compared the results given by paper chromato-graphy with those obtained for methylated monosaccharides on silica gellayers, and other investigators have published results obtained with celluloselayers,so Kieselgel G with sodium acetate 61 or boric acid,61, e2 and silica gelwith sodium hydrogen ~ u l p h i t e .~ ~Paper chromatography and partition chromatography on columns. Somany Papers were published under these classifisations that a very carefulselection of only the most important, in general terms, had to be made.Hesse 64 has found that the most important causes of change in, and lossof, substances during chromatographic separations are acid/base reactions,oxidation by heavy-metal oxides, autoxidation, and catalytic decomposi-tions by the stationary phase.Thoma a5 has applied regular solution theoryto the problem of selecting solvent components, and concluded that it is45 J. P. Garel, Bull. SOC. chim. France, 1965, 1899.46 V. D. Canic, M. N. Tur&ic, S. M. Petrovic, and S. E. Petrovic, Analyt. Chem.,4 7 E. Gagliardi and G. Pokorny, Mikrokhim. Ichnoanalyt. Acta, 1965, 699.48 H. HranisavljeviB- Jakovljevi6, I. Pej kovi6-Tadi6, and J. Milj kovib-Sto janovi6,49 E. V. Milborrow, J . Chromatog., 1965, 19, 194.50 M.M. Frodyma and R. W. Frei, J . Chromatog., 1965, 17, 131.5 1 J. A. Attaway, R. W. Wolford, and G. J. Edwards, Analyt. Chetn., 1965, 37,5 2 E. S. Lane, J . Chromatog., 1965, 18, 426.53 K. Egger and H. Kleinig, 2. analyt. Chem., 1965, 211, 187.64 E. Stahl and H. Vollmann, Tahnta, 1965, 12, 525.5 5 M.-D. Nutting, M. Voet, and R. Becker, Analyt. Chem., 1965, 37, 445.66 E. Sawicki, T. W. Stanley, W. C. Elbert, and M. Morgan, Talanta, 1965, 12,S. Chiba and T. Shimomura, Agric. and BioZ. Chem. (Japan), 1965, 29, 486.68 G. G. S. Dutton, K. B. Gibney, P. E. Reid, and K. N. Slessor, J . Chromatog.,59 A. Roudier, Bull. SOC. chim. France, 1965, 271.6o D. W. Vomhof Bnd T. C. Tucker, J . Chromatog., 1965, 17, 300.61 P. G. Pifferi, Anulyt. Chem., 1965, 37, 925.62H.Jacin and A. R. Mishkin, J . Chromatog., 1965, 18, 170.6s S. Adachi, J . Chromatog., 1965, 17, 295.84 G. Hesse, 2;. analyt. Chem., 1965, 211, 5.65 J. A. Thoma, Analyt. Chem., 1965, 37, 600.1965, 37, 1576.Mikrochim. Ichnoanalyt. Acta, 1965, 141.74.605.1965, 20, 163J. B. HEADRIDGE, T. B. PIERCE, D . M . w. ANDERSON 515often more profitable to study variations in solvent proportions rather thanchanges in the solvent components. Synthetic computer-generated peakshave been used 66 to investigate the effects of impurities on peak displace-ments and band broadening.decreases the time required forseparations of cations, and high-temperature paper chromatography hasalso led to faster separations.Badami 69 has reviewed reversed-phase partition column chromato-graphy. Berg 70 has inter-connected a series of individual columns, of suc-cessively decreasing volume, with glass couplers to facilitate larger-scaleseparations ; submicrogram amounts of thirteen metals have been separated '1from 50 grams of uranyl nitrate.The separation of fatty acids from C, to C16 has been achieved,52 onpaper impregnated with dimethylformamide, after their conversion intoNN- dimethyl-p- amino benzene- azop henac yl esters .A mercury film on platinum has been used 73 as the stationary phase in achromatographic separation of thallium, lead, indium, and tin in which theretention time depends on the applied potential.Nolecular-sieve chromatography.This technique is clearly in its infancy,and many of the greatly increased number of applications reported in thepast year have been highly specialised and empirical; Photaki has publisheda short Re~iew.~4 Many of the results reported have been obtained 759 76by using the Sephadex range of cross-linked dextrans, and some of the lesshighly cross-linked grades are best used with the reverse-flow technique.'?Column materials other than cross-linked dextrans are available for thistype of chromatography, e.g., silica gel,78 calcium phosphate,79 and theBio-Gel range of polyacrylamides .80Gm chromatography.A very large number of publications involving thistechnique continues to appear, and in this section also a very restrictedselection had to be made.Wilson and McInnes 81 have recommended an integration method ofeliminating errors arising from base-line drift in the measurement of peak66 P.D. Klein and B. A. Kunze-Falkner, Analyt. Chem., 1965, 37, 1245.67 Z. Zhu-Jun,ActaChim.8inkay 1965,31,355; Z.Dey1and J . Rosmus, J . Chromatog.,68D. French, J. L. Mancusi, M. Abdullah, and G. L. Brmnmer, J . Chrmatog.,ssR. C. Badami, Chem. and Id., 1965, 1211.70 0. W. Berg, Analyt. Chem., 1965, 37, 774.71 R. A. A. Muzzrtrelli and L. C. Bate, Tulunta, 1966, 12, 823.7 2 J . ChurGek, F. Kope6rly, M. Kulha*, and M. Jurecek, 2. analyt. Chem.,7 s W. J . Blaedel and J . H. Strohl, Anulyt. Chem., 1965, 37, 64.?OI. Photaki, Chimika Chronika, 1965, 30 A, 1.76 P. Andrews, Biochem. J., 1965, 06, 595.76A. A. Leach and P. C. O'Shea, J . Chromatog., 1965, 17, 245.77 F.Rothstein, J . Chromatog., 1965, 18, 36.781. P. Ting and W. M. Dugger, Analyt. Biochem., 1965, 12, 571.OS S. A. Kibardin, Uspekhi Khim., 1965, 34, 1472.A centrifugal acceleration technique1965, 18, 435.1965, 19, 445.1965, 208, 102.D. M. W. Anderson, I. C. M. Dea, S. Rahman, and J . F. Stoddart, Chem. Comm.,1965, 145; A. N. Schwartz, A. W. G. Yee, and B. A. Zabin, J . Chromatog., 1965, 20,164.81 J . D. Wilson and C. A. J . McInnes, J . Chromatog., 1965, 19, 486516 ANALYTICAL CHEMISTRYareas, and Teitelbauni 82 has discussed some errors that may arise in resultsfrom dual-column chromatographs. Other authors 83, 84 have also consideredsources of error in quantitative analyses, and electronic methods of elimi-nating tailing and of sharpening individual peaks in a gas chromatogramhave been published.85A low-pressure d.c.discharge detector has been described;86 it is simplet o construct and operate, and has a sensitivity comparable with the flame-ionisation detector.Dal Kogare 87 has considered the use of organic solids as adsorbents,and Dewar 88 has indicated some possible advantages of liquid crystals assolvents in gas chromatography. The advantages of operating at low tem-peratures has been Deans has published a useful techniquefor back-flushing columns that eliminates dead-space and stop-cocklubricants .A number of Papers have been concerned with the use of gas chromato-graphy in conjunction with some other technique: Juvet and Turner 91 havefollowed the controlled degradations given by high-intensity mercury radia-tion; several authors, e.g.,92 have continued to devise trapping-systems tocollect g.1.c.fractions for investigation by infrared, ultraviolet, or massspectroscopy ; and there has been increased interest in investigations of thepyrolysis products of natural 93 and synthetic 94-g6 polymers.Tri-fluoroacetylacetonates have been investigated g' with an electron capturedetector, and 2-2 x 10-l2 g. of rhodium can be detected. Juvet and Fisher 98have separated a number of heavy metals as their fluorides, using a thermalconductivity detector fitted with nickel filaments to resist corrosion.Of the organic applications, the use of trimethylsilyl derivatives has ledto advances in the separation of inositols, 99 pentaerythritols,lOO and sugars ;lo1the latter have also been separated after conversion to their alditol acetates.102Other complex natural products to have been investigated include the VitaminTwo papers are likely to lead to important inorganic advances.8 2 C.L. Teitelbaum, Analyt. Chem., 1965, 37, 309.8 3 M. F. Barakat, 2. analyt. Chem., 1965, 209, 384.8 5 J. W. Ashley, jun., and C. N. Reilley, Analyt. Chem., 1965, 37, 686.88M. J, S. Dewar and J. P. Schroeder, J. Org. Chem., 1965, 30, 3485.89 W. A. Van Hook and M. E. Kelly, Analyt. Chenz., 1965, 37, 508.OO D. R. Deans, J. Chromatog., 1965, 18, 477.SIR. S. Juvet, jun., and L. P. Turner, Analyt. Chem., 1966, 37, 1464.szH. T. Badings and J. G. Wassink, J. Clarmtog., 1965, 18, 159.93 S.Glassner and A. R. Pierce, Analyt. Chem., 1965, 37, 525.O 4 R. L. Gatrell and T. J. Mao, Analyt. Chem., 1965, 37, 1294.95 B. Kolb, G. Kemmner, K. H. Kaiser, E. W. Cieplinski, and L. S. Ettre, 2. aizalyt.$ 6 F. G. Stanford, Analyst, 1965, 90, 266.9 7 W. D. Ross, R. E. Sievers, and G. Wheeler, jun., Analyt. Chenz., 1965, 37, 59s.$8R. S. Juvet, jun., and R. I;. Fisher, Analyt. Chem., 1965, 37, 1752.99 Y. C. Lee and C. E. Ballou, J. Chromatog., 1965, 18, 147.B. D. Sully and P. L. Williams, Analyst, 1965, 90, 643.E. R. Fisher and M. M. McCarty, jun., Analyt. Chem., 1966, 37, 1208.S. Dal Nogare, Amlyt. Chem., 1965, 37, 1450.Chenz., 1965, 209, 302.l o o R. R. Suchanec, Analyt. Chem., 1965, 37, 1361.l01 J. S. Sawardeker and J.H. Sloneker, Analyt. Chenz., 1965, 37, 945.lo2 J. S. Sawardeker. J. H. Sloneker, and A. Jeanes, Analyt. Chenz., 1965, 37,1602J . B . HEADRIDGE, T . B . PIERCE, D . M . w. ANDERSON 517D group,lO3 glyceride ~ i l s , ~ ~ ~ and amino-acids as their N-trifluoroacetyl-n-butyl esters .lo5Ion-exchange. Schmuckler 106 has reviewed the properties and analyticalapplications of chelating resins. Although publications in this field in 1965have been largely inorganic in nature, organic topics have included (a;) theseparation of aldehydes in the bisulphite form,l07 ( b ) the separation of amines,particularly diamines, on cation resins loaded with nickel ions,lo8 ( c ) theseparation of monosaccharides by an automated procedure,log and (d ) thepreparation and properties of quaternary cellulose anion-exchangers.llOThe use of liquid ion-exchangers has continued to attract attention:Irving and Damodaran ll1 have determined perchlorate in the presence ofother halogen acids by means of a coloured anion-exchanger; Rao andSastri 112 have separated some elements on silica columns treated with aliquid cation-exchanger.An interesting preliminary report 113 has shownthat liquid ion-exchangers can be used to pre-treat silica gel for use in thin-layer chromatography.Ion-exchange selectivity scales have been published 114 for a large numberof cations, in nitric acid and in sulphuric acid media, on a sulphonated poly-styrene resin. Thiocyanate- based eluants have been used frequently,lI5and several groups of investigators have studied general separations of thealkali meta1s,ll6 the alkaline earths,llT and the rare earths.ll8 More specificapplications have included the determination of rhenium ;l19 the separationof silver ;12* and analyses of bronze,121 silicate rocks,122 and thorium-uraniumand plutonium-thorium-uranium alloys.123Electrophoresis. Gross 124 has published a Review of electrophoresis inlo3 P.P. Nair, C. Buca,na, S. De Leon, and D. A. Turner, AnaZyt. Chem., 1965,lo* T. L. Mounts and H. J. Dutton, Analyt. Chem., 1965, 37, 641.lo5 W. M. Lamkin and C. W. Gehrlre, AnaZyt. Chem., 1965, 37, 383; F. Marcucci,lo6 0. Schmuckler, Talaiata, 1965, 12, 281.lo' K. Christofferson, Analyt. Chim Acta, 1965, 33, 303.lo8 J. J. Latterell and H.F. Walton, Analyt. Chim. Acta, 1965, 32, 101.log L. A. Larsson and 0. Samuelson, Acta Chem. Scand., 1965, 19, 1357.110 R. R. Benerito, B. B. Woodward, and J. D. Guthrie, AnaZyt. Chenz., 1965,37, 1693.ll1 H. M. N. H. Irving and A. D. Damodaran, Analyst, 1965, 90, 443.112 A. P. R'ao and M. S. Sastri, 2. analyt. Chem., 1965, 207, 409.113 U. A. T. Brinkman and G. de Vries, J. Chronzatog., 1965, 18, 142.114 F. W. E. Strelow, R. Rethemeyer, and C. J. C. Bothma, Analyt. Chena., 1965,37, 106.115 A. K. Majumdar and B. K. Mitra, 2. analyt. Chem., 1965, 208, 1; D. J. Pietrzykand D. L. Kiser, Analyt. Chem., 1965,37,233; H. Hamaguchi, K. Ishida, and R. Kuroda,dltalgt. Chim. Acta, 1965, 33, 91.116 E. D. Olsen and R. L. Poole, jun., Analyt. Chem., 1965, 37, 1375; F.Nelson,D. C. Michelson, H. 0. Phillips, and K. A. Kraus, J. Chromatog., 1965, 20, 107; E. D.Olsen, and H. R. Sobel, Takznta, 1965, 12, 81.11' R. Christova and P. Ilkova, Analyt. Chim. Acta, 1965, 33, 434; M. H. Campbell,dnalyt. Chenz., 1965, 37, 262.118 B. L. Jangida, N. Krishnamachari, M. S. Varde, and V. Venkatasubramanittn,Analyt. Chiin. Acta, 1965, 32, 91.119 S. Kallmann and H. K. Oberthin, Analyt. Chem., 1965, 37, 280.lz0 A. V. Rangnekar and S. M. Khopar, Mikrochim. Ichnoanalyt. Acta, 1965, 642.121A. K. De and A. K. Sen, 2. analyt. Chem., 1965, 211, 213.122 A. D. Maynes, Analyt. Chim. Acta, 1965, 32, 211.lZ3 E. A. Huff, Analyt. Chem., 1965, 37, 533.lz4 D. Gross, Analyst, 1965, 90, 380.57, 631.E. Blussini, F. Poy, and P.Gsgliardi, J. Chromatog., 1965, 18, 48751 8 ANALYTICAL CHEMISTRYstabilising media. The more interesting developments have included appli-cations of continuous electrophoretic separation,l25 quantitative filter-paperelectrophoresis by means of reflectance densitometry,lZ6 the identification ofaromatic substances by “ electrophoretic spectra,” 127 and the use of ‘‘ Cel-logel” strips,128 which combine the advantages of both gel and paperelectrophoresis.Thorium, protactinium, and uranium have been separated as theiroxalate ~ornplexes,l~~ and organic applications have included separations ofsugars by high-voltage paper electrophoresis,l30 preparative zone electro-phoresis of proteins on polyacrylamide gels in 8~ urea,131 and the identifica-tion and assay of antibiotics by electrophoresis in agar gel.1324.Gravimetric halysis.-An important series of papers has been contri-buted by Klein and his co-workers, who have studied fundamental aspectsof the co-precipitation of lead with barium sulphate,l33 and also the kineticsof the precipitation by thioacetamide of zinc sulphide and nickel sulphide.134Klein and Swift 135 have further observed that two distinct nucleation pro-cesses may occur in the thioacetamide precipitation of metal sulphides.Other investigators 136 have also studied aspects of the precipitation ofmolybdenum sulphide by thioacetamide.Considerable attention has been paid to precipitation from homogeneoussolution, e.g., of aluminium as basic aluminium benzoate,137 of lead sulphateby sulphamic and of zirconium tetramandelate by hydroxypropylmm1de1ate.l~~ Precipitation from homogenous solution has also been usedfor the determination of barium, strontium, and calcium in barium per-oxide,140 and for the elimination of co-precipitation errors in the determina-tion of nickel with cyclohexane-l,2-dione dioxime.141As was the case last year, there have been very few papers on gravi-metric procedures for anions, although Heslop and Pearson142 have usedradionuclides to study the effect of arsenate and transition metals on theprecipitation of phosphate as ammonium molybdophosphate.Arsenic isalso precipitated under the conditions necessary for the quantitative preci-pitation of phosphorus, and the presence of ferric nitrate inhibits the preci-pitation of phosphorus.125 N.E. Skelly, Analyt. Chem., 1965, 87, 1526.126 A. L. Latner and D. C. Park, CZin. Chim. Ada, 1965, 11, 538.127 J. Franc and W. Kov&3, J . Chromatog., 1965, 18, 100.12s H. Keller and H. Seeger, 2. anaZyt. Chem., 1965, 212, 125.129 E. Merz, 2. analyt. Chem., 1965, 211, 331.130M. Ferencik and I. Ciznar, Chem. Zisty, 1965, 59, 332.1 3 1 P . H. Duesberg and R. R. Rueckert, AmZyt. Bkchem., 1965, 11, 342.132 J. W. Lightbown and P. De Rossi, Analyst, 1965, 90, 89.133 D. H. Klein and B. Fontal, Talanta, 1965, 12, 35.134 D. H. Klein and E. H. Swift, Talanta, 1965,12,349; D. H. Klein, D. G. Peters,135 D. H. Klein and E. H. Swift, Talanta, 1965, 12, 363.136 F. Buriel-Marti and A. Macerira-Vidan, Anales real Xoc.espaii. B’Fia. Quim., 1965,137 R. J. Irving, Talanta, 1965, 12, 1046.138 J. E. IColes, P. A. Shinners, and W. F. Wagner, Talanta, 1965, 12, 297.139 J. C. Rowe, L. Cordon, and W. G. Jackson, Tahnda, 1965, 12, 101.lQo G. Norwitz, Analyst, 1965, 90, 554.141P. D. Jones and E. J. Newmrtn, A d y s t , 1965, 90, 112.1 4 2 R . B. Heslop and E. F. Pearson, Analyt. Chim. Acta, 1965, 33, 522.and E. H. Swift, Tdantu, 1965, 12, 357.61, B, 867J. B. HEADRIDGE, T. B. PIERCE, D . M. w. ANDERSON 519Palladium has been determined with salicyloylhydrazide,l43 and a newreagent, 3,3-diphenylindane-l,2-dione dioxime, has been proposed 144 forthis metal. Christopher and Fennell 145 have studied the determination, asquinoline silicomolybdate, of silicon in organic materials.The preparationof sodium tetrakis-(p-chlorophenyl) borate has been described ;Ia6 it offerspossibilities for determinations of potassium, rubidium, cesium, quaternaryammonium, and protonated basic nitrogen compounds. Rubidium andcmium have also been determined with NN-dimethylethanolamrnonium0r0tate.l~'A new method of precipitating uranium, involving paminobenzoic acidand pyridine in aqueous solution, has been described.148 An interestingmicrogravimetric determination of gold 149 as bis( trimethy1)decamethylene-diammonium tetrabromoaurate(r) allows determination of 700 pg. gold inthe presence of 200-fold excesses of copper and nickel and 50-fold excesses ofother transition metals.5,5'-Thiodisalicylic acid 15* shows promise as a reagent for lead(=),zirconyl(n), indium(m), thorium(Iv), cerium-(m) and -(Iv), and other rareearths.The precipitation of calcium as molybdate,151 and the direct gravi-metric determination of calcium in silicates,152 have been studied.Many other publications in this section appeared during the year, butspace restricts any further mention to the following: the determination ofantimony with 1,2-dim0rpholylcthane,~5~ the determination of thorium inzirconium-hafnium mixtures by aromatic polycarboxylic acids,154 the deter-mination of lanthanum with N - ben~oyl-N-phenylhydroxylamine,~~5 thedetermination of indium with benzenephosphonic acid,156 and the deter-mination of beryllium as a double complex of hexamminecobalt(n1) ion witha di beryllium tricarbonato- complex .I575.Visual Titrations.-As in 1964 most of the progress in visual titrationsfor 1965 has involved redox and complexometric reactions, and rela-tively few papers on acid-base and precipitation titrations have beenpublished.Redox. A saturated solution of hexamminecobalt(1n) tricarbonato-cobaltate(1n) in saturated sodium hydrogen carbonate solution has been usedas a titrant for the determination of iron(@, vanadium(rv), and cerium(m)in acid solution. The hydrated cobalt(1rr) ion is released in acid solution.S. C. Shome and H. R. Das, Analyt. Chim. Acta, 1965, 32, 400.14* L. S. Bark and D. Brandon, Talanta, 1965, 12, 781.145 A. J. Christopher and T. R. F. W. Fennell, Talanta, 1965, 12, 1003.14* F. P.Cassaretto, J. J. McLafferty, and C. E. Moore, Analyt. Chim. Acta, 1965,N. Z. Babbie and W. Wagner, TaEanta, 1965, 12, 105.148 R. Ripan and V. Sacelean, Talanta, 1965, 12, 69.14s M. Ziegler and H. Neygenfind, Mikrochim. Ichnoanalyt. Acta, 1965, 729.150 M. L. Good and S. C. Srivastava, Talanta, 1965, 12, 181.151 K. F. Kharitonovich and M. L. Chepelevetskii, Zhur. anaEit. Khim., 1965, 20,lS2 A. D. Maynes, Analyt. Chim. Acta, 1965, 32, 288.153 E. Asmus and D. Ziesche, 2. analyt. Chem., 1965, 210, 177.154 A. K. Mukherji, 2. analyt. Chem., 1965, 209, 321.lS5 B. Das and S. C. Shome, Analyt. Chim. Acta, 1965, 32, 52.156 A. K. Mukherji, 2. analyt. Chem., 1965, 210, 260.15' G. Gottschalk and P. Dehmel, 2. analyt. Chem., 1965, 212, 380.32, 376.743520 ANALYTICAL CHEMISTRYVisual, potentiometric, or photometric end-point detection may be em-ployed .158Titrimetric methods for the determination of reducing sugars have beenreviewed.159 Benzoquinones and naphthaquinones have been determinedby reacting them with an excess of standard titanium(n1) chloride solutionat room temperature and back-titrating the unreacted titanium(@ withstandard iron( 111) solution, using ammonium thiocyanate as indicator.l60Ozonides in alcohol solution have been quantitatively determined by reactionwith an excess of triphenylphosphine followed by titration of unreactedtriphenylphosphine with standard iodine solution.l6lR i , ,O-0, ,R' R',RZ \o/ '' R2 R23- Ph3P cj.2 ,C=O + PhJPOPhJP + I, HlO Ph3PO 4- 2H1Parathion (diethoxy-p-nitrophenoxyphosphine sulphide) in solid samplesand emulsion concentrates has been determined by reaction with excess ofstandard chloramine-T solution, followed by the addition of potassiumiodide solution and the titration of liberated iodine, equivalent to the un-reacted chloramine-T, with standard thiosulphate solution.162(R),R'PS + 5H,O --+ (R),R'PO + SO,2- + 10H+ + 80Glycerol has been satisfactorily determined by adding copper( 11) chloridein slight excess to the alkaline solution, removing the precipitate of copper(n)hydroxide by filtration, and determining the copper(I1) in the copper(1r)-glycerol complex by adding sulphuric acid and potassium iodide, and titrat-ing the liberated iodine with standard thiosulphate s01ution.l~~A short Review on chelometric titrations has beenpublished 164 and complexometric methods in clinical analysis have beenreviewed.165 The determination of tervalent and quadrivalent metallic ionsby complexometric titration has been reviewed,166 and the effect of nitrilo-triacetate on the standardisation of solutions of EDTA has been examined.lG7The theory of complexometric titrations based on extractive end-pointdetection has been published.168 Further contributions to the theory ofcomplexometric titrations have been reported, and the sharpness of visual,photometric, potentiometric, and amperometric end-point detection hasbeen discussed.16gComplexometric.168 J.A. Baur and C. E. Bricker, Analyt. Chem., 1965, 37, 1461.lSD C. Hennart, Bull.SOC. chirn. France, 1965, 1588.160 T. Gerstein and T. S. Ma, Mikrochim. Ichnoanalyt. Actn, 1965, 170.0. Lorenz, Arzalyt. Chem., 1965, 37, 101.lea V. Laxminarayana and A. R. V . Murthy, Chenaist-Analyst, 1965, 54, 9.lsa J. T. McAloren and G. F. Reynolds, AnaZyt. Chim Acta, 1965, 32, 170.164 C. N. Reilley, Analyt. Ghein., 1965, 37, 1298.166 A. Holasek, 2. analyt. Chem., 1965, 212, 90.166 R. Pi.ibi1, Talanta, 1965, 12, 925.la' R. N. P. Farrow and A. G. Hill, Analyst, 1965, 90, 210.1*8 E. Still, Talanta, 1965, 12, 817.lBS M. Tanaka and G. Nakagawa, Analyt. Chiin. Acta, 1965, 32, 123J. B . HEADRIDGE, T. B. PIERCE, D . M . W . STDERSON 521Interference from iron( 111) in the complexometric back-titration of excessof EDTA or DCTA over zinc, lead, cobalt, nickel, copper, and cadmium a tpH 5-0-5-5, with standard lead nitrate solution as titrant, is prevented byprecipitating the iron as potassium hexafluoroferrate(m) on the addition offluoride and potassium ions.170 It has been reported that the interaction ofXylenol Orange with cetylpyridinium bromide allows the extension of itsuseful range as indicator to pH 11.Under these conditions sharp end-pointsare obtained with Xylenol Orange in the titration of calcium, zinc, man-ganese( II), magnesium, and cadmium in alkaline solutions using EDTA astitrant . l 7 1Calcium in serum and urine has been determined by EDTA titarationusing Hydroxy Naphthol Blue as indicator. Iron, magnesium, copper,phosphate, and bilirubin in concentrations normally encountered in serumand urine did not interfere with the reaction of the indi~ator.17~ Microgramquantities of zirconium have been satisfactorily determined by titration inO~05-2~3~-hydrocholoric acid with standard EDTA solution using MethylThyinol Blue as indicator.The effects of other ions on the titration havealso been rep0rted.l7~The interference by phosphate and fluoride in the mercurimefric titrationof chloride using diphenylcarbazone as indicator has been eliminated by pre-cipitating phosphate and fluoride with thorium nitrate solution before thetitration. Such a titration has been applied to the determination of chlorinein organic compounds containing phosphorus and fluorine after an oxygenflask combustion.l 74 A method based on titration with o-hydroxymercuri-benzoic acid has been described for the determination of aliphatic and aro-matic mercaptans in organic solvents using thiofluorescein as indicator.175Sulphur, carbon disulphide, and other disulphides do not interfere.A new indicator made by coupling diazotised 4-nitro-aniline-2-sulphonic acid with chromotropic acid is suitable for the titrimetricdetermination of sulphate ions with standard barium solution. There is nointerference from a 15-fold excess of phosphate.176Standard solutions of silver nitrate and o-hydroxymercuribenzoic acidhave been used as titrants with p-dimethylaminobenzylidinerhodamine asindicator for the titrimetric determination of chloride, bromide, iodide,thiocyanate, ferrocyanide, tetraphenylboron, thiourea, thiosemicarbazide,diphenylurea, t,hioacetamide, o-phenylenethiourea, ethylenethiourea, 00-diethyldithiophosphoric acid, and mercaptans in acidic aqueous ethanolsolutions.o-Hydroxymercuribenzoic acid forms soluble complexes witht.hese substances and the titrations with this reagent are actually based oncomplexometric rather than precipitation reactions.177-4cid-base. Carbon in iron and steel has been determined by combustionPrecipitation.l i 0 R. Pi.ibi1 and V. Veself, Talanta, 1965, 12, 385.171 V. ChromJi and V. Svoboda, Talanta, 1965, 12, 437.172 G. Cartledge and H. G. Briggs, Clinical Chem., 1965, 11, 521.173 S.-C. Hung and H.-S. Chang, Acta Chim. Sinica, 1964, 30, 492.li4 A. F. Colson, AnaZyst, 1965, 90, 35.l i 5 M.Wronski, 2. analyt. Chem., 1964, 206, 352.176 V. I. Kuznetsov and N. N. Basargin, Zacodskaya Lab., 1965, 31, 538.li7 M. Wronski, Talanta, 1965, 12, 593522 ANALYTICAL CHEMISTRYof the sample in a stream of oxygen, absorption of the carbon dioxide thusproduced in dimethylformamide, and titration of this solution with astandard solution of tetra-n-butylammonium hydroxide in benzene-methanol using Thyrnolphthalein as indicator. An automatic potentio-metric titration can also be employed.1786. Instrumental Titrations.-In 1965 a large number of papers appearedon potentiometric titrations, and amperometric and coulometric titrationsreceived considerable attention, but papers on conductometric, photometric,and thermometric titration formed only a small proportion of all those oninstrumental titrations.Potentiometric titrations. A further contribution to the theory of poten-tiometric titrations in glacial acetic acid has now been published.l7Q Mono-basic acids with pKa values up to 5.5 have been determined in acetonitrilein the presence of their anhydrides by potentiometric titration with a stan-dard solut,ion of tri-n-propylamine in acetone.180 Sulphinic acids and mix-tures of sulphinic and sulphonic acids have been determined with goodaccuracy and precision by potentiometric titration in nonaqueous solventsusing quaternary ammonium hydroxides as titrants ,181Constant-current potentiometric end-point detection with two smallplatinum electrodes has been applied successfully to the determination of10-60 p.p.m.of water in organic solvents using Karl Fischer reagent astitrant and N-ethylpiperidine as catalyst.182 Wranium(vI) has been deter-mined by reduction to uranium(1v) with an excess of iron(=) in 12~-phos-phoric acid solution, followed by potentiometric titration with standardpotassium dichromate s01ution.l~~Milligram quantities of chlorate have been determined in phosphoricacid solution with osmium tetroxide as catalyst by potentiometric titrationwith standard ferrous ammonium sulphate solution. Chlorate is reduced tochloride.184 Chlorate has also been determined by direct potentiometrictitration with standard arsenite with osmium tetroxide as ~ata1yst.l~~Milligram amounts of bromide and iodide have been satisfactorily deter-mined by potentiometric titration with standard lead(1v) acetate solution.lSsThe same titrant has also been employed in the potentiometric titration oforganic sulphides in aqueous acetic acid solution.The sulphides are oxidisedto s~lphoxides.~~~A continuous automated potentiometric titrator with a flow-throughdropping mercury electrode has been described for the precise complexo-metric determination of metal ions at millimolar concentrations.la8 Poten-tiometric end-point detection with a silver indicator electrode and with178 R. F. Jones, P. Gale, P. Hopkins, and L. N. Powell, Analyst, 1965, 90, 623.lSo H. W. Wharton, Analyt. Chem., 1965, 37, 730.181 D. L. Wetzel and C. E. Meloan, Analyt. Chem., 1964, 36, 2474.lS3 G.G. Rao, P. K. Rao, and M. A. Rahman, Tahnta, 1965, 12, 953.lS4 J. Vulterin, Coll. Czech. Chem. Comm., 1965, 30, 1505.Is5 P. K. Norkus, Zhur. analit. Kltim., 1965, 20, 496.186 V. Buzkova, N. Moldan, and J. Zyka, Coll. Czech. Chern. Comm., 1965, 30, 28.M. Tanaka and G. Nakagawa, Analyt. Cltirn. Acta, 1965, 33, 543.E. E. Archer and H. W. Jeater, Analyst, 1965, 90, 351.L. Suchomelova, V. Horak, and J. Zyka, Microchem. J., 1965, 9, 201.W. J. Blaedel and R. H. Laessig, Analyt. Chem., 1965, 37, 1255J . B. HEADRIDGE, T. B. PIERCE, D . M. w. ANDERSON 523EDTA as titrant has been applied to the direct titrimetric determination ofbarium, bismuth, cadmium, calcium, cerium(rv), cobalt(@, copper(n), mer-c u r y ( ~ ) , lanthanum, magnesium, manganese( n), nickel, lead, strontium, andzinc in borate buffer solution after the addition of silver-EDTA complex.A back-titration procedure was used for the determination of aluminium,thorium, thallium(rn), and zirconium.169 Bismuth, indium, and thoriumhave been satisfactorily titrated in 0~2~-monoch~oroacetic acid solution atpH 2 with standard EDTA solution using a ferrous-ferric system as indicatorand potentiornetric end-point detection.1900.01-3 =mole samples of perchlorate have been determined with goodprecision, after reaction with an excess of solid vanadium(1n) sulphate in8M-sulphuric acid in the presence of osmium tetroxide catalyst, followed bypotentiometric tit<ration of the resulting chloride with standard silver nitiratesolution .l 91A high-sensitivity recording conductomet)ric titratorhas been described for the determination of low concentrations of acid orother species in the presence of high concentrations of foreign electrolytes.192An apparatus for automatic, conductometric, acid-base titrations in non-aqueous media has been described.193Amperornetric.The smperometric titration of organic compounds hasbeen revie~ed.1~4Biamperometric end-point detection using lead amalgam electrodes hasbeen applied to the titrimetric determination of lead with standard EDTAsolution.195 Biamperometric titration with two carbon electrodes has beensuccessfully employed for the determination of 1-150 mg. of iron(m) usingstandard EDTA as titrant. Many common metallic ions, and cations, haveno interfering effect on the uetermination.lg6 Biamperometric titration withtwo stationary platinum electrodes can also be used for the determination of1-150 mg.of copper(=) with standard EDTA as titrant.lg7 A rapid methodfor the precise determination of silver in non-ferrous metals by amperometrictitration with sodium diethyldithiocarbamate in ammoniacal medium hasbeen described.ls8 Amperometric end-point detection using a rotatingplatinum electrode has been applied to the precise determination of uranium-(m) by titration with standard iron(m) solution.19QAn automatic amperometric titrator using a stationary mercury electrodehas been described for the titration of sulphate with standard lead nitratesolution.200 Amperometric end-point detection has been applied to theConductometric.lS9 F.Strafelda, (2011. Czech. Chem. Comm., 1965, 30, 2320.190 T. Nomina, T. Dono, and G. Nakagawa, Japan Analyst, 1965, 14, 197.lBID. A. Zatko and B. Kratochvil, Analyt. Chem., 1965, 37, 1560.lg2 T. R. Mueller, R. W. Stelzner, D. J. Fisher, and H. C. Jones, Analyt. Chem.,lo3 W. Boardmas and B. Warren, Chern. a d Ind., 1965, 1634.lg4 A. Berka, J. Doleial, and J. Zyka,, Chemist-Analyst, 1965, 54, 24.Io5 H. L. Kies, J . Electroanalyt. Chern., 1964, 8, 325.lg6 J. VorliEek and F. Vydra, Talanta, 1965, 12, 377.lg7 J. VorliEek and F. Vydra, Talenta, 1965, 12, 671.lo* V. I. Lotareva, Zhur. analit. Khim., 1965, 20, 790.1965, 37, 13.R. F. Syrnpson, R. P. Larsen, R. J. Meyer, and R. D. Oldham, AnaEyt. Chem.,S.A. Myers, jun., and W. B. Swann, Talanta, 1965, 12, 133.1965, 37, 68524 A N ,4 L Y T I C B L C H E MI S TR Ydetermination of inorganic chlorides and bromides in glacial acetic acid usingstandard cadmium nitrate solution as titrant .201 Perchlorate has been deter-mined by amperometric titration with a standard solution of fetraphenyl-stibonium sulphate. There is no interference from chloride, chlorate, nitrate,phosphate, or sulphate.202Both aliphatic and aromatic amines have been determined in a dioxan-water mixture, which is 1~ in hydrochloric acid, by amperometric titrationa t +0.4 v (s.c.e.) using a standard solution of calcium hypochlorite as titrant.The 27-chloroamides are produced in the rea~tion.~03Photometric. A further contribution to the theory of photometric titra-tion curves in the presence of indicators is reported for complexometric andacid-base tit ration^.^^^ The construction and evaluation of a semi-immersionphototitrator has been de~cribed.~O~Iron(m), in the presence of high concentrations of bismuth in solutions ofpH 2-3, has been determined by spectrophotometric titration with standardEDTA solution using sulphosalicylic acid as indicator.The bismuth ismasked with a high concentration of ammonium chloride.206 Photometricend-point detection has been applied to the determination of thiols by titra-tion with standard ammonium chloropalladite solution using p-nitrosodi-methylaniline as indicator.207The application of thermometric titration to redoxreactions has been discussed.208 It has been shown that when acids in ace-tone solution are titrated with non-aqueous alkali solution, a rapid rise intemperature occurs beyond the end-point, owing to the formation of diace-tone alcohol. The method has been applied to the precise determination of2,6-&substituted phenols, keto-enols, and imide~.~O~ Alkylaluminium com-pounds have been satisfactorily determined by thermometric titration, therecommended titrants being di-n-butyl ether, benzophenone, t- butyl alcohol,and isoquinoline.210 Thermometric titration has also been applied to thedetermination of diethylzinc in hydrocarbon solution, with o-phenanthrolineand 8-hydroxyquinoline as titrants.211The principles of coulometric titrimetry 213 and recentdevelopments in this technique 213 have been reviewed.Automatic recordingequipment for continuous coulometric titrations has been described.214The capabilities of a relatively simple coulometric titrator have been assessedThermometric.Coulometric.801 A. P. Kreshkov, V. 9. Bork, L. A. Shvyrkova, and M. I. Apasheva, 2hw. analit.202 M. D. Morris, Aizalyt. Chem., 1965, 37, 977.Z o 3 W. R. Post and C. A. Reynolds, Analyt. Chem., 1965, 37, 1171.304 E. Still and A. Ringbom, Analyt. Chim. Acta, 1965, 33, 50.205 H. Flaschka and J. Butcher, Talanta, 1965, 12, 913.206 H. Flaschka and J. Garrett, Talanta, 1964, 11, 1651.207 H. Haglund and I. Lindgren, Talanta, 1965, 12, 499.208 J. Barthel and N. G. Schmahl, 2. analyt. Chem., 1965, 207, 81.209 G.A. Vaughan and J. J. Swithenbank, Analyst, 1965, 90, 594.210 W. L. Everson and E. M. Ramirez, Analyt. Chem., 1965, 37, 806.211 W. L. Everson and E. M. Ramirez, Analyt. Chem., 1965, 37, 812.212 E. Bishop, Lab. Practice, 1965, 14, 928.*13 V. A. Mirkin, Zavodskaya Lab., 1965, 31, 395.214 T. Takahashi and H. Sakurai, J . Chem. SOC. Japan, Ind. Chem. Sect., 1961, 67,Rhint., 1965, 20, 704.1802J . B. HESDRIDGE, T. B . PIERCE, D . 31. W. ANDERSOX 525for the standardisation of acid solutions. Results of excellent accuracy andprecision were obtained.2150.01-10 mg. Amount's of titanium have been determined by reducing thetitanium to the 3+ state with zinc amalgam and titrating the titanium(Ir1)with electrically-generated iron(m), with amperometric or potentiometricend-point detection.216 Iridium(1v) in the presence of rhodium(n1) wasdetermined by titration with electrically generated iron(I1) or ferrocyanide,with potentionietric end-point detecti0n.~17 Molybdenum(v1) has beensatisfactorily determined by titration with electrically-generated titanium-(111), using amperometric or potentiometric end-point detection.218Silica in glasses, glass ceramics, and refractories has been determined bydirect coulometric titration of an excess of 8-hydroxyquinoline used toprecipitate the silico-12-molybdate complex, with electrically-generated bro-mine using amperometric end-point detection.219 Electrogeneration ofchromium( 11) in 1 -5~-hydrochloric acid with high current efficiency hasbeen achieved by reducing the penta-aquobromochromium(1u) ion.Thechromium(I1) thus produced was used to titrate aromatic nitro-compoundswith fairly good accuracy and precision.220 Protein nitrogen has beendetermined in as little as 1 pl. of serum by direct titration of the ammonia inKjeldahl digests with electrically generated hypobromite, using ampero-metric end-point detection.221The coulometric generation of ethylene glycol bis-(p-amino-ethyl ether)-XN'-tetra-acetic acid from mercury-EGTA complex a t the mercury poolanode has been employed for the titration of calcium in the presence ofmagnesium using potentiometric end-point detection.2227. Quantitative Organic Analysis.-EZementuZ. Vecera 223 and his co-workers have published a submicro-method for the determination of carbon,in which the carbon dioxide evolved is measured conductometrically.Belcher et ~ 6 1 .~ ~ ~ have described a manometric method for the submicro-determination of carbon and hydrogen. The water and carbon dioxideformed are trapped at -80" and - 196" respectively and excess of oxygen ispumped out: the trapped gases are expanded into fixed volumes and theirpressures measured by a piston-type burette system and a photoelectriclevel indicator. The method is free from interferences from nitrogen, sulphur,and the halogens other than fluorine.Another interesting method determines 225 both carbon and hydrogen as2 * 5 E. L. Eckfeldt and E. W. Shaffer, jun., Analyt. Chem., 1965, 37, 1534.?16 Z. Slovak and M. Pribyl, Z . analyt.Chena., 1965, 211, 247.217 N. I. Stenina and P. K. Agasyan, Zhur. analit. Khirn., 1965, 20, 351.E. Binder, G. Goldstein, P. Lagrange, and J.-P. Schwing, Bull. SOC. chim. Prance,219 Y . Su, D. E. Campbell, and J. P. Williams, Analyt. Chint. Acta, 1965, 32, 559.220 D. A. Aikens and M. Carlita, Analyt. Chem., 1965, 37, 459.221 G. D. Christian, E. C. Knoblock, and W. C. Purdy, Clinical Chem., 1965, 11, 413.222 G. D. Christian, E. C. Knoblock, and W. C. Purdy, Analyt. Chem., 1965, 37,233 M. VeEePa, J. Lakom9, and L. Lehar, Mikrochim. Ichnounulyt. Acta, 1965, 674.P. Gouverneur, H. C. E. Van Leuven, R. Belcher, and A. M. G. Macdonald,1965, 2807.29,.Analyt. Chirn. Acta, 1965, 33. 360.*z5 H. S. Haber, D. A. Bude, R. P. Buck, and K. W. Gardiner, Analyt.Chem.,1965, 37, 116526 ANALYTICAL CHEMISTRYwater, after combustion in a quartz tube. Hydrogen is det,ermined codo-metrically as water in a special electrolytic cell; the carbon dioxide from com-bustion is converted into an equivalent amount of water, by means of aspecially prepared charge of lithium hydroxide, and determined in a secondelectrolytic cell.Israelstam 226 has reported a rapid, simple, semimicro-method fordetermining carbon and hydrogen; AZicino 227 has discussed the use of ver-miculite in such determinations.Holmes and Lauder 228 have developed the use of gold to remove mercuryin carbon and hydrogen determinations on organic compounds contain-ing mercury, and a Hungarian paper 229 considered the determinationof carbon, hydrogen, silicon, and germanium in organometallic com-pounds.Gas-chromatographic methods have been given for determinations ofnitrogen 230 and of carbon, hydrogen, and nitr~gen.~~l Monar proposed 232three simple procedures, of general application to organic and many organo-metallic compounds, for micro-determinations of carbon, hydrogen, nitrogen,and oxygen ; with an automatically controlled apparatus, determinations ofthese elements are possible within 11 minutes.Considerable attention has been given this year to the determination ofoxygen on the micro 2a3 and sub-micro 234 scales, and Holt has described 235a new technique, involving a oarbon-reduction bed in an induction-heatedgraphite tube, for the direct determination of oxygen in organophosphoruscompounds.Schoniger has published recommendations based on experiencesof the Unterzaucher procedure over a period of 10 years.23* Belcher, Davies,and West 237 carried out a useful comparison of some of the modifications tothe Schutze method that have been proposed in the past; the main conclu-sions reached were that pyrolysis should be carried out over platinisedcarbon at goo", that both reduced copper and sods asbestos are required toremove interfering vapours, and that the determination should be completedgravimetrically, after conversion of carbon monoxide to dioxide with Schutzereagent a t room temperature.A considerable number of Papers dealt with the determination of elementsother than carbon, hydrogen, nitrogen, and oxygen, and Taubinger andWilson238 recommended the use of 50% hydrogen peroxide for the wetoxidation of organic materials.Rowe 23@ has determined chlorine at less226 S. S . Israelstam, Microchem. J., 1965, 9, 193.227 J. F. Alicino, Microchem. J., 1965, 9, 22.ISo I. E. Pakhomova and M. N. Chumachenko, Izvest. Akad. Nauk S.S.S.R., Ser.2s1 K. Derge, Chem-Ing.-Tech., 1966, 37, 718.2Sa I. Monar, Milcrochirn. Ichnoadyt. Acta, 1965, 208.aasP. M. Mietasch and J. Hor&Eek, Coll. Czech. Chern. Comm., 1965, 30, 2889.2s4 K. Yoshikawa and T. Mitsui, Microchem. J., 1965, 9, 52.235 B. D. Holt, Analyt. Chem., 1965, 37, 751.a36 W. Schoniger, Mikrochim. Ichmandyt. Acta, 1965, 679.R. Belcher, D. H. Davies, and T. S. West, Tahnta, 1965, 12, 43.as8 R. P.Taubinger and J. R. Wilson, Analyst, 1965, 90, 429.259 R. D. Rowe, Analyt. Chem., 1965, 37, 368.T. F. Holmes and A. Lauder, Andy&, 1965, 90, 307.T. Aranyi and A. Erdey, Magyar Kdm. Lap& 1965, 20, 164.Khim., 1965, 1138J . B . HEADRIDGE, T . B . PIERCE, D. M . w. ANDERSON 527than 10 p.p.m. in polybutenes, and other papers concerned with halogens 240have given methods for their simultaneous deterrninafi~n.~~~The determination of sulphur has also attracted the attention of severalin~estigators,~4~ and methods for the determination of sulphur in the pre-sence of and of selenium 244 have also been described. Merzhas published ultramicro-procedures for the determination of sulphur andnitrogen,245 and Belcher et aL246 have studied submicro-methods for phos-phorus and arsenic.Pmctional groups.Many interesting Papers, involving a wide range offunctional groups, were published in this section in 1965. Kaiser247 hassuggested that the results of functional group analyses should be publishedin terms of a " functional number," which he defined.Belcher and his co-workers have published several papers during theyear on the submicro-determination of olefinic ~ n s a t u r a t i o n , ~ ~ ~ deactivatedole fin^,^*^ nitrogen grou~s,~~O acetyl groups,251 thiol groups,252 and on theperiodate oxidation reactions of ~arbohydrates.~5~There have been several publications involving aspects of the determina-tion of alkoxyl groups in specialised c i r c u r n s t a n c e ~ , ~ ~ ~ - ~ ~ ~ and papers on thedetermination of epoxy-c~rnpounds,~~~ ethylene oxide, and oxyalkenegroups.255, 258 Sulphydryl and disulphide groups have been investi-gated,254, 259 and hydroxyl groups still continue to attract attention.26*240 D.Pitr6 and M. Grandi, Mikrochim. Ichnoanalyt. Acta, 1965, 193; E. Pella,241 J. C. Mamaril and C. E. Meloan, J. Chromatog., 1965,17, 23; T. V. Reznitskaya242 J. DokladalovA, Mikrochim. Ichnoanalyt. Acta, 1965, 344; T. Takeuchi, I.243 N. Kramer, Mikrochim. Ichnoanalyt. Acta, 1965, 144.2 4 p Z. Stefanac and Z. RakoviE, Mikrochim. Ichnoanalyt. Acta, 1965, 81.245 W. Merz, 2. analyt. Chem., 1965, 207, 424.216 R. Belcher, A. M. G. Macdonald, S. E. Phang, and T. S. West, J . Chem. Soc.,2 4 7 R. Kaiser, 2. analyt. Chem., 1965, 212, 369.248 R.Belcher and B. Fleet, J . Chem. SOC., 1965, 1740.250 R. Belcher, Y. A. Gawargious, and A. M. 0. Macdonald, J . Chm. Soc., 1964, 5698.251 A. K. Awasthy, R. Belcher, and A. M. G. Macdonald, Analyt. Chim. Acta, 1965,252 R. Belcher, Y. A. Gawargious, and A. M. G. Macdonald, Analyt. Chim. Acta,*j3 R. Belcher, G. Dryhurst, and A. M. G. Macdonald, J. Chem. SOC., 1965, 3964.254 J. A. Magnuson and E. W. Knaub, Analyt. Chem., 1965, 37, 1607.2 5 5 F. Ehrenberger, 2. analyt. Chem., 1965, 210, 424.256 P. Dostal, J. Cermak, and B. Novotna, Coll. Czech. Chem. Comm., 1965, 30, 34;V. A. Klimova, K. S. Zabrodina, and N. L. Shitikova, Izvest. Akad. Naub S.S.S.R.,Ser. Khim., 1965, 178, 1288; A. I. Lebedeva and E. S. Pkarenko, Zhur. analit. Khim.,1965, 20, 630.257 J.Urbanski and G. Kainz, Mikrochim. Ichnoanalyt. Acta, 1965, 60.258 J. R. Kirby, A. J. Baldwin, and R. H. Heidner, Analyt. Chem., 1965, 37, 1306;N. A. Kolchina, Zhur. analit. Khim., 1965, 20, 380; F. W. Cheng, Microchem. J., 1965,9, 270; N. AdIer, J . Pharm. Sci., 1965, 54, 735.259 M. Krsteva, B. V. Alexiev, C. P. Ivanov, and B. Yordanov, Amlyt. Chim. Acta,1965, 32, 465; R. E. Humphrey, A. L. McCrary, and R. M. Webb, TaZunta, 1965, 12,727.260 V. Iyer and N. K. Mathur, Analyt. Chim. Acta, 1965,33,554; R. Harper, S. Siggia,and J. G. Hanna, Analyt. Chm., 1965, 37, 600; K. S. Panwar and J. N. Gaur, AnaZyt.Chim. Actu, 1965, 33, 318; D. D. Singer and J. W. Stiles, Analyst, 1965, 90, 290.ibid., 1965, 369.and E. I. Burtseva, Zhw.analit. Khim., 1965, 20, 225.Fujishima, and Y. Wakayama, ibid., p. 635.1965, 2044.R. Belcher and B. Fleet, Talanta, 1965, 12, 677.33, 311.1965, 33, 210528 AN AL Y TI C AL CH E MIS TRYStroh and Liehr 261 have studied the determination of 0- and N-acetylgroups in sugar hydrazone acetat'es and n.1n.r. spectroscopy has been usedin an investigation of N-methyl groups.262Other papers worthy of note involved determinations of hydrazino-groups,263 alkyl and aryl groups,264 a ~ i d e , ~ ~ ~ the carbonyl group,266 andamino and carboxyl end-groups 267 in Nylon.8. Spectroscopic Analysis.-X- Ray $fluorescence spectroscopy and relatedtechniques. Mass absorption corrections in the X-ray fluorescence analysisof igneous rocks have been discussed,2*8 Experimental conditions and re-sults are reported for the analysis of alloys and compounds of high-meltingmetals by X-ray fluorescence spectros~opy.~~~ Reasonably accurate andrapid analysis for silicon, potassium, calcium, titanium, manganese, and ironin rocks has been achieved using X-ray fluorescence spectrography.Pressedpellets of cellulose-diluted rock powders were used.27oThe X-ray fluorescence determination of strontium in food and bone hasbeen described, where the specimen is mixed and briquetted with an organicbinder. Transmittance measurements on the briquettes with monochro-matic Sr-K, radiation allows a correction to be applied to the fluorescent8r-K, X-rays from specimens of differing X-ray 0pacity.~7l Tin in powdersamples has been determined by two X-ray fluorescence methods. The first,a non-destructive general method, in which thick films are used, is fast butless accurate than the second method, which involves fusing the sample in agraphite crucible with a borate flux after the addition of antimony trioxideas internal ~tandard.~7~ Minor amounts of tantalum in niobium have beendetermined by X-ray analysis with direct electron excitation.The limit ofdetection was 200 p.p.m. and the precision (relative standard deviation) was2% in the o.4-5y0 concentration range.273The determination of oxygen in silicates by soft X-ray spectrophotometryhas been described. For oxygen over the range 44--54%, relative standarddeviations of better than 1 yo have been achieved in routine rock analysis.274Xethods involving the use of plastics have been described for obtaining solidsamples for the X-ray fluorescence analysis of mineral oils and organicsolutions.275 Limits of detection for the X-ray fluorescence analysis ofelements in mineral oils have also been determined.276The technique of internal differential X-ray absorption edge spectrometry261 H.-H.Stroh and H. Liehr, J . prakt. Chem., 1965, 29, 8 .262 J. C. N. Ma and E. W. Warnhoff, Canad. J . Chem., 1965, 43, 1849.263 F. G. Hoffman and D. G. Shaheen, Microchem. J . , 1965, 9, 63.264 J. Franc, J. Dvoracek, and V. KolouSkovh, Mikrochim. Ichnoanalyt. Acta,2 6 5 R. G. Clem and E. H. Huffman, Analyt. Chent., 1965, 37, 366.266 A. P. Terentiev and I. S. Novikova, Zhur. analit.Khiin., 1965, 20, 836.267 R. G. Garmon and M. E. Gibson, Analyt. Chem., 1965, 37, 1309.z6* J. G. Holland and E. I. Hamilton, Spectrochinz. Acta, 1965, 21, 206.z69 E. Lassner, R. Puschel, and H. Sohedle, Talanta, 1965, 12, 871.Z 7 O D. F. Ball, Analyst, 1965, 90, 258.2'1 M. Goldman and R. P. Anderson, Aizalyt. Chena., 1955, 37, 718.2'2 K. G. Carr-Brion, Analyst, 1965, 90, 9.273 C. J. Toussaint and G. Vos, Analyt. Chiin. -4cta, 1965, 33, 279.s74A. K. Baird and B. L. Henke, Analyt. Chem., 1965, 37, 727.Z i 6 G. Rothe and A. Koster-Pflugmacher, 2. analyt. Chem., 1965, 213, 173.276 R. Louis, Z . analyt. Chem., 1965, 208, 34.1965, 4J. B. HEADRIDGE, T. B . PIERCE, D . 31. w. ANDERSOX 529has been described. The results are independent of sample geometry andsurface condition.2i7The automation of data evaluation in quanti-tative spectroscopy has been described.2i8 Voltage fluctuation patternshave been obtained for many elements in the d.c.arc. These recordings giveinformation about sample consumption time, arc stability, and reproduci-b i l i t ~ . ~ i Q In a detailed study, cathode excitation was compared with anodeexcitation under the same conditions for 33 elements in the d.c. arc. It wasconcluded that cathode excitation affords greater precision for a number ofmore volatile elements in a carbon matrix.280 The emission characteristicsand sensitivity in a high-voltage spark discharge between an aluminium- basealloy and graphite counter electrode ha.ve been investigated using time-resolved emission spectrometry.281A general procedure has been described for the determination of elementsin the range O .l - l O O ~ o with a single set of working curves using spectro-graphic analysis of powdered samples by rotating disc-spark technique. Theaccuracies and precisions are reasonable.282 An emission spectrographicmethod has been described for the determination of major elements incements with a relative accuracy of & 1-4%.283 A direct-reading spectro-graphic method has been applied to the analysis of 500 pg. samples of non-metallic materials for aluminium, calcium , chromium , magnesium, man-ganese, phosphorus, silicon, and titanium. The limits of detection are aboutSpectrographic detection limits for many elements in tungsten have beendetermined,285 and a method has been described for the spectrographicanalysis of zirconium, whereby 36 impurity elements are determined simul-taneously with limits of detection of 1 x %.The relativeerrors were 10-20%.286 A spectrographic method has been developed forthe determination of ultramicro-amounts of boron ( X . 0 6 p.p. t housnndmillion) in high-purity silicon tetrachloride and trichlorosilane.28710--200 p.p.m. of oxygen in steel have been determined by automaticemission-spectrography using a high temperature hollow-cathode dischargeto melt the sample and excite the atomic spectrum of oxygen, measurementsbeing made on the oxygen multiplet a t 7772/5 In connexion with theemission-spectrometric determination of oxygen in metals it has been shownthat a master analytical curve for oxygen can be constructed without theuse of standard metal samples.289 The d.c.carbon-arc extraction techniquehas been adapted to the direct-reading determination of oxygen in highEmission spectroscopy.1 pg.280to 1.5 x277 T. J. Cullen, AnaZyt. Chem., 1965, 37, 711.278 H. Franke, K. Post, and W. Schmotz, 2. analyt. Chem., 1965, 212, 269.2 i s J. W. Mellichamp, Analyt. Chem., 1965, 37, 1211.280 R. R. Brooks and C. R. Boswell, AnaZyt. Chim. Acta, 1965, 32, 339.281 J. P. Walters and H. V. Malmstadt, Anabyt. Chem., 1965, 37, 1484.282 M. G. Atwell and G. S. Golden, Analyt. Chem., 1965, 37, 1597.283 Z. G. Hanna and J. M. Ibrahim, Z . analyt. Chem., 1965, 214, 33.284 M. Reckziegel, G.Staats, and H. Brueck, 2. analyt. Chenz., 1964, 206, 113.285 R. Dyck, Analyt. Chem., 1965, 37, 1046.286 0. F. Degtyaxeva and L. G. Sinitsyna, Zhur. anabit. Khim., 1965, 20, 603.287 K. Kawasaki and M. Higo, Analyt. Chim. Ada, 1965, 33, 497.2B8 M. S. W. Webb and R. J. Webb, Anabyt. Chim. Acta, 1965, 33, 138.289 V. A. Fassel and J. W. Goetzinger, Spectrochim. Acta, 1965, 21, 289530 ANALYTICAL CHEMISTRYand low alloy steels having oxygen contents ranging between 0.0048 and0.085 wt.The operating parameters of a spectrographic plasma jet have been evalu-ated, and it has been shown that quantitative analysis can be achieved byplasma spectrophotometry under non-interference conditions in multi-element environments.291 The application of the plasma jet to the spectro-chemical analysis of aqueous solutions has been investigated.292 A stabilizedplasma arc has been employed as an excitation source for the determinationof 10-4-10-3% of boron in petrol.The precision was t3%,293Phme photometry. Recent developments in flame spectrophotometricand atomic absorption spectroscopic analysis have been and a,theoretical treatment to explain the shapes of calibration graphs for flamespectrophotometry has been published.2g5 The use of turbulent flames aslight sources for the analysis of solutions by flame photometry has beeninve~tigated.~~A thorough study has been made of the mutual radiation interferenceeffects of the alkali elements and hydrogen upon the resonance line intensitiesof the alkali elements in flame ~pectrophotometry.~97 The precise deter-mination of sodium in uranium, phosphate, carbonate, and silicate rocks byflame spectrophotometry has been described.The enhancement effects ofother alkali metals were overcome by using a radiation buffer.298 Calciumand potassium in soil extracts have been determined automatically by flamephotometry using a Technicon Auto Analyser. Magnesium and phosphoruswere determined simultaneously using atomic absorption spectroscopy andthe Molybdenum Blue colorimetric procedure respectively.299Aluminium oxide (0.1-60%) in refractory products has been determinedby a flame-photometric procedure after solvent extraction as its acetylace-tonate into chlorof0rm.3~~ Copper and magnesium in blood serum have beensatisfactorily determined by high-resolution spectrophot~rnetry.~~~ Flamespectrophotometry with an oxy-acetylene flame has been satisfactorilyapplied to the determination of trace amounts of palladium and rhodiumafter solvent extraction into 4-methylpentan-%one of the salicylaldoximecomplex and diethyldithiocarbamate complex respectively.302XpectroJluorimetry .Solution spectrofluorimetry as a trace technique ininorganic analysis 303 and the phosphorescence spectroscopy of aromatic andheterocyclic compounds have been reviewed.304 Preliminary investigations290 C. Matsumoto, V. A. Fmsel, and R. N. Kniseley, Spectrochim. Acta, 1965, 21,889.2 0 1 E. H. Sirois, Analyt. Chem., 1964, 36, 2389 and 2394.292 P. A. Serin and K. H. Ashton, Appl.Spectroscopy, 1964, 18, 166.293 M. S . Vigler and J. K. Failoni, AppZ. Spectroscopy, 1965, 19, 57.294 H. Herrmann, 2. analyt. Chem., 1965, 212, 1.295 J. Winefordner, T. Vickers, and L. Remington, AnaZyt. Chern., 1965, 37, 1216.2~ M. E. Britske, Zavodskaya Lab., 1964, 30, 1465.297 E. L. Grove, C. W. Scott, and F. Jones, Talanta, 1965, 12, 327.298 H. Kramer and L. J. Pinto, AnaZyt. Chim. Acta, 1965, 33, 438.Z9@ J. Lacy, Analyst, 1965, 90, 65.300 W. Schmidt, K. Konopicky, and J. Kostyra, 2. analyt. Chern., 1964, 206, 174.3O1 R. L. Warren, Analy8t, 1965, 90, 549.308 H. C. Eshelman, J. Dyer, and J. Armentor, AnaZyt. Chim. Acta, 1965, 52, 411.303 T. 8. West, Lab. Practice, 1965, 14, 922 and 1030.304 M. Zander, Chem.-Ing.-Tech., 1965, 37, 1010J.B. HEADRIDQE, T. B. PIERCE, D . M. w. ANDERSON 531into the application of sensitized P-type delayed fluorescence to organictrace analysis have been made,305 and further applications of quenchofluori-metric analysis (the quenching effect of solvents on fluorescence) for poly-iiuclear compounds have been reported.306Thallium(1) at concentrations 20.01 p.p.m. has been determinedspectrofluorimetrically in concentrated hydrochloric acid-potassium chloridemedium. The effects of interfering elements were thoroughly examined.3070.05-50 p.p.m. of zinc as its complex with dibenzothiazolylmethanehas been determined fluorimetrically in aqueous ethanol solution. Themethod was applied to the determination of trace amounts of zincin cadmium and of minor amounts of zinc in magnesium-base all0ys.~083.6 x 10-4-3.6 x 10-2 p.p.m.of boron as boric acid have been determinedfluorimetrically by making measurements on the complex formed betweenboric acid and 4’-chloro-2-hydroxy-4-methoxybenzophenone in concen-trated sulphuric a ~ i d . ~ O ~A fluorimetric method has been described for the determination of hydro-gen peroxide at the ~ O - * M level. The method is based on the oxidation ofnon-fluorescent diacetyldichlorofluorescein to a fluorescent compound byhydrogen peroxide and p e r o ~ i d a s e . ~ ~ ~ A method has been described for thecontinuous determination of 5 parts of hydrogen sulphide in 1O1O parts ofair to 1 part in lo7. It is based on the reduction of fluorescence, which occurswhen hydrogen sulphide is absorbed into 0.0005% (w/v) tetra-acetoxy-mercurifluorescein in 0.0025 % (w/v) sodium hydroxide s ~ l u t i o n .~ ~ l Aspecific fluorimetric method for the detection of cyanide has been described.As little as 0.5 pg. of cyanide gives a highly fluorescent product with quinonemonoxime benzenesulphonate ester. There is no interference from 30 othercommon anions.312 Further studies on the fluorimetric determination ofcyanide have also been reported.313A spectrofluorimetric method for the determination of oxalic acid inblood and other biological materials has been described. The limit of detec-tion is 0.9 p mole of oxalic acid.314 Microgram quantities of atropine havebeen determined fluorimetrically by means of the fluorescent compoundformed between atropine and eosin?15 Spectrofluorimetric methods havealso been described for the determination of histamine in microgram samplesof tissue or microlitre volumes of body f l ~ i d s , ~ l 6 and of m-hydroxyphenyl-ethylamine (m-tyramine) and its analogues.317 0.01 pg.or more of haemC. A. Parker, C. G. Hatchard, and T. A. Joyce, Analyst, 1965, 90, 1.E. Sawicki, T. W. Stanley, and H. Johnson, Mikrochim. Ichnoanalyt. Acta,G. F. Kirkbright, T. S. West, and C. Woodward, TaZanta, 1965, 12, 517.M. Marcantonatos, A. Marcantonatos, and D. Monnier, AeZv. Chim. Acta, 1965,1965, 178.s08R. R. Trenholm and D. E. Ryan, Analyt. Chim. Acta, 1965, 32, 317.slo A. S . Keston and R. Brandt, Analyt. Biochem., 1965, 11, 1.sll T. R.Andrew and P. N. R. Nichols, AnuZy.yt, 1965, 90, 367.sla G. G. Guilbault and D. N. Kramer, AnaZyt. Chem., 1965, 37, 918.31s G. G. Guilbault and D. N. Kramer, Analyt. Chem., 1965, 37, 1395.s15 S. Ogawa, M. Morita, K. Nishiura, and K. Fujisawa, J . Phrm. SOC. Japan,a16 D. Von RedIich and D. Glick, Analyt. Biochem., 1965, 10, 459.s17 W. F. Coulson, A. D. Smith, and J. B. Jepson, Analyt. Biochem., 1965, 10, 101.48, 194.M. Zarembski and A. Hodgkinson, Biochem. J., 1965, 96, 717.1965, 85, 650532 ANALYTICAL CHEMISTRYprotein in animal tissues has been determined spectrofluorimetrically afterconverting the protein’s haem moiety into its fluorescent porphyrin deri-~ative.~18Procaine, cocaine, phenobarbital, chlorpromazine, and atropine have beendetermined phosphorimetrically in blood serum or urine after extraction withchloroform or ether, evaporation of the solution to dryness, and dissolutionof the residue in a mixture of ethyl ether, isopentane, and ethanol.319 Afterextraction from tobacco and separation by thin-layer chromatography,nicotine, nornicotine, and anabasine have been determined phosphori-metrically in ethanol-sulphuric acid with a precision of 6%.320Atomic absorption spectroscopy.The application of this technique to theanalysis of alloys has been discussed with emphasis on accuracy, detectionlimits, and possible extensions of the method.321 A study of the distributionof atoms in an air-acetylene atomic absorption flame has been rep0rted,~2~background corrections in long-path atomic absorption spectrophotometryhave been discussed,323 and factors affecting the shape of analytical curvesin atomic absorption spectroscopy have been considered.324High-intensity hollow-cathode lamps, which emit resonance lines somehundred times more intense than can be obtained from conventional hollow-cathode lamps, have been developed.s25 An integrating analogue computerhas been described for atomic absorption spectrophotometry with systemsfor which the noise level would ordinarily be excessive for satisfactoryanalysis.The detection limit for calcium using the apparatus was 0.003p .p .m .32sParts per million of magnesium in uranium have been satisfactorilxdetermined by atomic absorption spectroscopy without prior ~eparation,~~and magnesium has been determined in alkali products and aluminium alloysby this technique after solvent extraction of magnesium 8-hydroxyquinolateor 8-hydroxyquinaldate into isobutyl methyl ketone.328 With a nitrogen-oxygen-acetylene flame the limit of detection for aluminium in aqueoussolution by atomic absorption spectroscopy is less than 2 p.p.m.Underthese conditions, the effect of potential interferences has been studied andsatisfactory results are reported for the determination of aluminium inalloys and 0res.32~ Atomic absorption spectroscopy has been employed forthe determination of tin in hydrogen peroxide solution using an oxyhydrogenflame and the 2863 A tin line. Concentrations of tin in excess of 0.05 p.p.m.were satisfactorily determined.330 Selenium has been determined by atomicabsorption spectroscopy with a limit of detection of 1 p,p.m.This technique318 G. R. Morrison, Analyt. Chem., 1965, 37, 1124.318 J. D. Winefordner and M. Tin, Analyt. Chim. Acta, 1965, 33, 61.320 J. D. Winefordner and H. A. Moye, Analyt. Chim. Acta, 1965, 32, 278.321 G. Sonnenmacher and F.-H. Schleser, 2. analyt. Chem., 1965, 209, 284.322 C. S. Ram and A. N. Hambly, Analyt. Chem., 1965, 37, 879.323 S. R. Koirtyohann and E. E. Pickett, Analyt. Cbm., 1965, 37, 601.324 I. RubePka and V. Svoboda, Analyt. Chim. Acta, 1965, 32, 253.325 J. V. Sullivan and A. Walsh, Spectrochim. Acta, 1965, 21, 721.326 E. A. Boling, Analyt. Chem., 1965, 37, 488.327 J. R. Humphrey, Analyt. Chem., 1965, 37, 1604.528 M.Suzuki, 1%. Yenagisawa, and T. Takeuchi, Talanta, 1965, 12, 989.329 M. D. Ames and P. E. Thomas, Analyt. China. Acta, 1965, 32, 139.330 E. J. Agazzi, Ataalyt. Chem., 1965, 37, 364J . B. HEADRIDGE, T. B . PIERCE, D . RX. W. ANDERSOX 533was applied with good results to the determination of selenium in wheat andgalena.331Atomic absorption spectroscopy has been applied to the determination ofchromium after extraction of chromium( VI) into isobutyl methyl ketone.With an air-hydrogen flame the detection limit was 0.006 p.p.m. of chro-mium.332 A method has been described for the direct determination of0.05-10~0 of iron in aluminium alloys using atomic absorption spectro-scopy. After a solvent extraction of iron with isobutyl methyl ketone, aslittle as 5 p.p.m.of iron in high-purity aluminium can be determined.333Copper in sea-water has been satisfactorily determined by atomic absorptionspectroscopy after extraction of the copper-ammonium pyrrolidine dithio-carbamate complex into ethyl acetate and spraying of the organic extract intothe flame.334 Zinc in biological materials has been determined with goodaccuracy and precision by direct atomic absorption spectrophotometry. Thelimit of detection was 0.002 p.p.m. of zinc in s0lution.~~5 Traces of copper,chromium, iron, lead, and silver in used lubricating oil have been satisfac-torily determined by atomic absorption measurement of solutions of the oilin 4-methylpentan-2-0ne.~~6Atomic fluorescence flame spectrometry has been applied to the deter-mination of zinc, cadmium, mercury, gallium, indium, and thallium usingimproved equipment.The limits of detection for zinc and cadmium are0.0001 p.p.m. and 0.0002 p.p.m. respectively.337Ultraviolet and visible spectrophotometry . Very few Papers of a generalnature were published, although Ramaley and Enke 338 have proposed theuse of isomation, in which standard solutions and a calibration curve arereplaced by one standard solution.Heteropolyacids have been studied from two different viewpoints :Chalmers and Sinclair 339 have studied the determination of arsenic, ger-manium, and phosphorus ; Billman et aZ.340 have used 12-molybdosilicic acidfor the determination of carbonyl compounds. Diphenylpicrylhydrazyl maybe used 341 for the analysis of amines, and isonitrosoacetanilide has beenreported 342 to give a specific reaction with palladium in acidic media, and avery sensitive reaction with cobalt in ammoniacal solution.The determination of aluminium has been the subject of several interest-ing Papers.West et have described a simple and rapid method for the331 C. S . Ram and A. N. Hambly, Analyt. Chirn. Ada, 1965, 32, 346.332 F. J. Feldman and W. C. Purdy, Andyt. Chim. Acta, 1965, 33, 273.333 A. Atsuya, Japan Analyst, 1965, 14, 592.334 R. J. Magee and A. K. M. Rahman, TaZanta, 1965, 12, 409.335 K. Fuwa, P. Pulido, R. McKay, and B. L. Vallee, AnaZyt. Chem., 1964, 36,336 J. A. Burrows, J. C. Heerdt, and J. B. Willis, Analyt. Chern., 1965, 37, 579.337 J. M. Mansfield, J.D. Winefordner, and C. Veillon, AnaZyt. Chem., 1965, 37,338 L. Ramaley and C. G. Enke, Analyt. Chern., 1965, 37, 1073.339 R. A. Chalmers and A. G. Sinclair, Analyt. Chim. Acta, 1965, 33, 384.310 J. H. Billman, D. B. Borders, J. A. Buehler, and A. W. Seiling, AnaZyt, Chern.1965, 37, 264; J. H. Billman and A. W. Seiling, Analyt. Ghim. Acta, 1965, 33,561.3*1 G. J. Papariello and M. A. M. Janish, AnaZyt. Chem., 1965, 37, 899.343 R. M. Dagnall, T. S. West, and P. Young, Analyst, 1965, 90, 13.2407.1049.F. Buscarbns and F. Buscarhs, jun., Analyt. Chirn. Acta, 1965, 32, 568534 ANALYTICAL CHEMISTRYdetermination of as little as 0.001% aluminium in steel, and Pakalns 344 hasreported that Chromeazurol is a more satisfactory reagent than EriochromeCyanine R or Aluminon.A methods5 for determining antimony in therange 0.02-1.6 p.p.m. depends on the reduction of a molybdate aggregatea t pH 1-4. Thierig and Umland 346 have claimed that the use of Sulphonazo-111 gives the most sensitive and selective method available for determina-tions of barium. Determinations of boron with Diamino-Crysazin 347 andbarium chloranilate 348 have been described.Several methods have been proposed for determining copper, involvingSolochrome Azurine B.S. ,349 biscyclohexanone 0xalyldihydrazone,~~0 neo-cupr0ine,~~1 Acid Alizarin Black S.N. ,352 and Aminomethylazo III.3S3 Butlerand Forbes 354 have concluded, from a comparative study, that Dithizoneis to be preferred to Neocuproine or biscyclohexanone oxslyldihydrazonefor determinations of copper.Pike and Yoe 355 have studied the deep-blue stable chloro-complexesformed by cobalt in dimethylformamide.Two groups of investigators havestudied the determination of lanthanides.356 Methylthymol Blue has beenproposed 357 as a colorimetric reagent for magnesium.Stobart 35~4 has described a method for the determination of 3 p.p.m. oflead in heat-resistant alloy steel; West et have used 4-(2-pyridylazo)-resorcinol as a reagent for lead in steel, brass, and bronze.Belcher, Ramakrishna, and West 360 have found Bromopyrogallol Redto give the most sensitive visible-range spectrophotometric method proposedto date for niobium(v); Patrovsky361 has determined niobium with 4-(2-thiazoly1azo)-resorcinol .Platinum, palladium, and other noble metals have been investigated byseveral groups of workers,362 and Beamish 3133 has given a critical evaluationof colorimetric methods for these metals.Other elements for which interesting methods have been proposed are3 4 4 P.Pakalns, Analyt. Chim. Acta, 1965, 32, 57.345 R. M. Matulis and J. C. Guyon, Analyt. Chem., 1965, 37, 1391.346 D. Thierig and F. Umland, 8. analyt. Chem., 1965, 211, 161.347 A. R. Eberle and M. W. Lerner, Analyt. Chem., 1965, 37, 1568.248 D. R. Peterson and J. R. Hayes, Analyt. Chm., 1965, 37, 306.849 U. Tandon, S. N. Tandon, and S. S. Katiyax, Talantu, 1965, 12, 639.35O K. R. Middleton, Analyst, 1965, 90, 234.s 5 1 C. L. Luke, Analyt. Chim. Ada, 1965, 32, 286.35aM. Hosain and T. S. West, Andyt.Chim. Acta, 1965, 33, 164.353 B. Budesinsky and K. Haas, 2. analyt. Chem., 1965, 214, 325.354 E. J. Butler and D. H. S. Forbes, Andyt. Chim. Actu, 1965, 33, 69.365 L. Pike and J. H. Yoe, Tulanta, 1965, 12, 657.357 J. Metcalf, Andyst, 1965, 90, 409.368 J. A. Stobart, AnuZyst, 1965, 90, 278.359 R. M. Dagnall, T. S. West, and P. Young, Talunta, 1965, 12, 589.360 R. Beloher, T. V. Ramakrishna, and T. S . West, Tulunta, 1965, 12,681.S S l V . Patrovsky, Tahnta, 1965, 12, 971.363 C. F. Bell and D. R. Rose, Tulunta, 1965, 12, 696; M. A. Khattak and R. J.Magee, $M., p. 733; S. C. Srivastava and M. L. Good, Analyt. Chim. Acta, 1965,32, 309.363 F. E. Bemish, Talanta, 1965, 12, 743 and 789.W. J. Maeck, M. E. Kussy, and J. E. Rein, Analyt.Chem., 1965, 37, 103; B.Budcsinsw and K. Haas, 2. analyt. Chem., 1965, 210, 263J . B . HEADRIDGE, T. B . PIERCE, D . M. W. ANDERSON 536phosphorus,364 rhenium,365 thallium,366 thorium,367 uranium,368 and vana-dium( v) .36Infrared spectrophotmnetry. An automatic device, allowing up to 25samples to be run a t one loading, has been described.370A number of papers have described amlyses in which infrared measure-ments have been combined with some other technique, e.g., with X-rayfluorescence,371 thin-layer ~hrornatography,37~ gas ~hromatography,~7~ orfilament pyrolysis.374Several useful new sampling techniques that were described included theuse of silver chloride d i ~ k s , ~ 7 ~ the dispersion of samples in solid antimonytrichloride,376 and the use of molten sulphur as a s0lvent.~77 Auxiliaryinstrumentation devices worthy of note included a potassium wedge forcompensation purp0ses,~7~ variable-angle reflection attachments,379 and asimple semimicro-cell3130 for spectral reflectance measurements.Magee and Gordon381 continued their studies of chelates with a studyof the different forms of the uranium chelates of 8-hydroxyquinoline in theregion 5000-250 crn.-l, and methods were given for the determination ofpyrethrum extracts 382 and cationic surfa ce-active agent~.~*3Near-infrared measurements were used to determine 384 ammonia, carbondioxide, and water a t elevated temperatures and pressures, and analyses ofbutadiene polymers were made by combining the information from near-idrared and n.m.r.analyses.385Nuclear magnetic resonunee. Flockhart and Pink 386 have reviewed theanalytical applications of nuclear and electron magnetic resonance. Readand GoldsteinSS7 have described an integration method of increasing thea64 T. Salvage and J. P. Dixon, Analyst, 1965, 90, 24; W. Pilz, Mikrochim. Ichno-analyt. Acta, 1965, 34.A. K. De and M. S. Rahaman, Talanta, 1965, 12, 343; E. N. Pollock and L. P.Zopatti, Analyt. Chim. Acta, 1965, 32, 418.366 G. F. Kirkbright, T. S. West, and C. Woodward, Takznta, 1965, 12, 517; L. G.Hargis and D. F. Boltz, Analyt. Chem., 1965, 37, 240.a67 P. Kusakul and T. S. West, Analyt. Chim. Acta, 1965, 32, 301.s6sP. Spacu, F. Popea, and C. Tohaneanu, 2. analyt. Chem., 1965, 214, 338.369 0. Budevsky and L.Johnova, Talanta, 1965,12,291; J. A. Dougherty and M. G.370 N. L. McNiven, P. Hoffman, and G. Scrimshaw, Analyt. Chem., 1965, 37, 778.371 S. D. Kullbom, W. K. Pollard, and H. F. Smith, Analyt. Chem., 1965, 37, 1031.37a R. N. McCoy and E. C. Fiebig, Analyt. Chem., 1965, 37, 593.I. Schmeltz, C. D. Stills, W. J. Chamberlain, and R. L. Stedman, Analyt. Chem.,3 7 4 G. Lindley, Lab. Practice, 1965, 14, 826.376 L. L. Pytlewski and V. Marchesani, Analyt. Chem., 1965, 37, 618.376 H. Szymanski, K. Broda, J. May, W. Collins, and D.. Bakalik, Analyt. Chena.,3 7 7 T. K. Wiewiorowski, R. F. Matson, and C. T. Hodges, AnaEyt. Chem., 1965,378 H. McCormiclc, E. L. Deeley, and J. Tadayon, Nature, 1965, 207, 474.37s W. N. Hansen, Analyt. Chem., 1965, 37, 1142; N.J. Harrick, ibid., p. 1446.3B0 R. W. Frei and M. M. Frodyma, Analyt. Chim. Acta, 1965, 32, 501.3B1 R. J. Magee and L. Gordon, Talanta, 1965, 12, 445.383 J. H. N. Byrne, W. Mitchell, and F. H. Tresadern, Analyst, 1965, 90, 362.383 J. T. Cross, Analyst, 1965, 90, 315.384 J. G. Koren and A. J. Andreatch, Analyt. Chem., 1965, 37, 256.38b A. J. Durbetaki and C . M. Miles, Analyt. Chem., 1965, 37, 1231.386 B. D. Flockhart and R. C . Pink, Talanta, 1965, 12, 529.387 J. M. Read, jun., and J. H. Goldstein, Analyt. Chem., 1966, 37, 1609.Mellon, Analyt. Chem., 1965, 37, 1096.1965, 37, 1614; R. A. Edwards and I. S. Fagerson, ibid., p. 1630.1965, 37, 617.37, 1080536 AXALYTICAL CHEMISTRYsensitivity of n.m.r. measurements, and Brame 388 has devised a trap/cellwhich facilitates the examination of gas-chromatography fractions by n.m.r.spectroscopy.Reilley 389 has obtained information regarding the lability of the indi-vidual metal-ligand bonds formed when a multidentate complexing agentreacts with a metal ion; Kula has also shown the suitability of n.m.r.spec-troscopy for studying solution equilibria of metal ~helates,~~* and for deter-mining hydration numbers.391 Goodlett 392 has proposed the use of in situreactions (e.g., with reactive isocyanate) to characterise alcohols and glycolswithin the n.m.r. sample tube.9. Electrical Methods.--PoZurography. Reviews have been published onthe state of polarographic direct-current methods and their instrumenta-tion,393 on recent advances in polarography in Japan,394 on the polarographicanalysis of inorganic substances,395 and on the application of oscillographicpolarography in organic ~hemistry.~96 Cathode-ray polarography (potentialsweep chronoamperometry ) of anions has been discussed,397 and investiga-tions on the determination of mixtures by potential sweep chronoampero-nietry have been reported.398Details of an operational-amplifier, a.c.polarograph with admittancerecording have been published,399 and a controlled potential square wavepolarograph has been described.400 An apparatus for the continuous re-cording of cell respiration has been developed. It is based on the polaro-graphic determination of oxygen.401Polarographic reduction waves, suitable for analytical purposes, havebeen obtained for tin (IV) in perchlorate, tartrate, citrate, and ammoniacalsolutions in the presence of 3-mercaptopropionic a ~ i d .~ O ~ Tin( IV) in boiling1M-sodium hydroxide has been quantitatively reduced by sodium borohy-dride to tin( II), which was then determined polarographically using thereduction wave of half-wave potential - 1-15 v (~.c.e.).~03 The polarographicbehaviour of 35 ions in lM-ammonium fluoride solution adjusted to pH 7has been investigated, and a selective polarographic method for lead hasbeen reported.404 Trace amounts of lead in stainless steels have been deter-mined by differential cathode-ray polarography following a solvent-extractionseparation.405 5-500 p.p.m. of bismuth and lead have been determined388 E.G. Brame, jun., Analyt. Chem., 1965, 37, 1183.389 C. N. Reilley, Analyt. Chem., 1965, 37, 1298; R. J. Day and C. N. Reilley, ibid.,39O R. J. Kula, Analyt. Chern., 1965, 37, 989.391 R. J. Kula, D. L. Rabenstein, and G. H. Reed, Analyt. Chem., 1965, 37, 1783.3 9 2 V. W. Goodlett, Analyt. Chem., 1965, 37, 431.393 H. W. Niirnberg and G. Wolff, Chern.-Ing.-Tech., 1965, 37, 977.394 N. Tanaka, E. Itabashi, and T. Ito, J . Electrochena. SOC. Japan, 1964, 32, 119.395 I. V. Pyarnitskii, Zavodskaya Lab., 1965, 31, 6.396 G. K. Budnikov, Uspekhi Khirn., 1964, 33, 1371.3Q7 R. C. Rooney, J . Polarographic SOC., 1964, 10, 49.398 R. A. Osteryoung and E. P. Parry, J . Electroanal.yt. Chem., 1965, 9, 299.J. W. Hayes and C. N. Reilley, Analyt. Chern., 1965, 37, 1322.* 0 ° E.B. Buchanan, jun., and J. B. McCarten, Analyt. C’laent., 1965, 37, 29.401 P. G. Blunder and M. Modolell, Z. analyt. Chem., 1965, 212, 177.402 X. L. Phillips and R. A. Toomey, Analyt. Chena., 1965, 37, 607.403 D. H. Evans, Analyt. Chem., 1964, 36, 2435.404 A. G. Hamza and J. B. Headridge, Talanta, 1965, 12, 1043.405 R. C. Rooney, Analyst, 1965, 90, 545.1965, 37, 1326J. B. HE9DRIDGE, T. B. PIERCE, D . M. W. AKDERSON 53'7polarographically in copper-base alloys using an acidic tartrate base elec-trolyte, after solvent extraction as diethyldithiocarbamate complexes frominterfering elements . O6Small amounts of tellurium in cartridge brass and in white cast iron havebeen determined by cathode-ray polarography in 1.5~1-phosphoric acid asbase electrolyte.407 Trace amounts of iodide have been determined by theircatalytic effect on the polarographic reduction of indium(m).Other halidesand certain sulphur and nitrogen compounds exhibit a similar catalyticeffect.408Differential cathode-ray polarographic methods have been described forthe accurate determination of iron, nickel, manganese, zinc, cobalt, andcopper in ferrite materials.409 Pulse polarography has been applied to thedetermination of 0.5-50 p.p.m. of nickel and vanadium in petroleumsto~ks.~lO Small amounts of copper(n) in steels and cast irons have beendetermined by polarography in 0~5~-trioxyglutaric acid a t pH 12 as baseelectrolyte.411 Copper concentrates have been analysed for zinc after itssolvent-extraction separation from copper, iron, cobalt, cadmium, nickel,chromium, and mangane~e.41~ Molybdenum has been determined in niobium-base alloys by a quick polarographic method, the base electrolyte beingO*Ei~-hydrofluoric acid-0.5~-sulphuric acid.413 Trace amounts of rheniumin ores, slags, etc., have been determined polarographically after a separationof rhenium from other elements by steam distillation as rhenium heptoxidefrom concentrated sulphuric acid solution.414 A polarographic method hasbeen described for the determination of microgram amounts of gold in bloodand serum after the separation of gold from copper and iron by solventextraction.415 Different'ial cathode-ray polarography has been applied tothe determination of europium in solutions of lithium chloride and iodidewith a precision of 0.1~o.416Small amounts of methanol have been determined by oxidation to for-maldehyde with potassium permanganate in orthophosphoric acid followedby polarographic reduction of the formaldehyde to methanol at 50°.417Polarographic methods have also been described for the determination ofcrotonaldehyde in vinyl acetate,418 of benzotriazole in inhibited ethyleneVolturnmetry.The glassy carbon electrode has been investigated as anindicator electrode in voltammetry. In operation it compares very favourablyand of Sevin, 1 -naphthyl-N-methylcarbamidate.420406 C. H. McMaster, Canad. J. Chern., 1965, 43, 405.407 E. J. Maienthal and J. K. Taylor, AnaZyt. Chem., 1965, 37, 1516.408 A. J. Engel, J.Lawson, and D. A. Aikens, Anulyt. Chem., 1965, 37, 203.40g E. L. Bush and E. J. Workman, Analyst, 1965, 90, 346.Q1o D. D. Gilbert, AnaZyt. Chem., 1965, 37, 1102.411 E. G. Chikryzova and S. Ya. Mashinskaya, Zawodskaya Lab., 1966, 31, 26.412 J. Jankovsky, 2. analyt. Chem., 1965, 213, 84.413 J. B. Headridge and D. P. Hubbard, Analyst, 1965, 90, 173.414 R. Geyer, G. Henze, and H. Meutzner, 2. C?Len,., 1964, 4, 433.415 G. D. Christian, Clinical Chem., 1965, 11, 459.416 V. Verdingh and K. F. Lauer, Aizalyt. Chim. Acta, 1965, 33, 469.*I7 M. Ranny, Analyst, 1965, 90, 664.418 J. Pasciak, 2. analyt. Chem., 1965, 213, 111.419 S. Harrison and G. L. Woodroffe, Analyst, 1965, 90, 44.420R. Engst, W. Schnaak, and H. Woggon, 2. nnalyt. Chem., 1965, 207, 30.538 ANALYTICAL CHEMISTRYwith pyrolytic graphite and other solid ele~trodes.4~1 Voltammetric datahave been reported for inorganic ions with boron carbide electrodes422and a carbon paste electrode suitable for voltammetry in non-aqueous sol--snts has been described.423 A rapid voltammetric method based on thereduction of vanadium(v) to (IV) at a platinum electrode has been describedfor the determination of vanadium ( >0-01%) in steels.Common componentsof steel do not interfere.424Carbon dioxide in gas mixtures has been determined by saturating dime-thy1 sulphoxide with the gas mixture and measuring the current associatedwith the voltammetric reduction of carbon dioxide on an amalgamatedplatinum ele~trode.4~~ Many amines have been determined by voltammetricoxidation at a rotating platinum ele~trode.4~~The theory of anodic stripping voltammetry with a plane, thin mercury-film electrode has been An electrode consisting of mercurydeposited on graphite has been employed to obtain very sharp currentpeaks in anodic stripping ~oltamrnetry.4~8 The theoretical and analyticalcharacteristics of derivative measurement techniques have been evaluated€or reversible electrodepositions at the hanging mercury drop electrode usingelectrolysis with linearily varying potentia1.429 Derivative techniques havealso been applied to'anodic stripping v~ltamrnetry.~~~ It has been shownthat &.c. voltammetry at stationary electrodes, when applied to strippinganalysis, produces a significant increase in sensitivity over direct strippinganal~sis.~3~Anodic stripping voltammetry has been applied to the determination of5-1000 p.p.m.of copper in iron and stee1,4a2 ultramicro-amounts of antimonyand bismuth in germanium and germanium tetra~hloride,4~~ lead in blood,acopper, lead, and cadmium in biological materialsYa5 zinc in sea-water 436and mercury(I1) at a carbon-paste electrode ( < l a 2 5 x 1 0 - 5 ~ ) 437 and at awsx-impregnated graphite electrode ( 24 x 10-9~).4338Recent developments in this techniquehave been reviewed,439 and an analogue integrator for controlled-potentialcoulometry has been described.&OControlled-potential c o u h e t r y .421 H. E. Zittel and F. J. Miller, Analyt. Chem., 1965, 37, 200.422 W. R. Mountcastle, jun., Analyt.Chim. Acta, 1965, 32, 332.423 L. S. Marcoux, K. B. Prater, B. G. Prater, and R. N. Adams, And$. Chem.,424 G. Ciantelli and G. Raspi, Chimica e Industria, 1965, 47, 303.425 J. L. Roberts, jun., and D. T. Sawyer, J. Electroanalyt. Chenz., 1965, 9, 1.426 V. D. Bezuglyi and Yu. I. Beilis, Zhur. analit. Khim., 1965, 20, 1000.427 W. T. de Vries and E. van Drtlen, J . Electroanalyt. Chem., 1964, 8, 366.4as W. R. Matson, D. K. Roe, and D. E. Carritt, Andyt. Chem., 1965, 37, 1594.4 2 9 S. P. Perone and T. R. Mueller, Analyt. Chem., 1965, 37, 2.430 S. P. Perone and J. R. Birk, Analyt. Chem., 1905, 37, 9.431 W. L. Underkofler and I. Shah, Analyt. Chem., 1965, 37, 218.432 G. Gottesfeld and M. Ariel, J . Ekctroanalyt. Chem., 1965, 9, 112.433 E.N. Vinogradova and A. I. Kamenev, Zhur. analit. Khim., 1965, 20, 183.434 J. F. C. Tyler, Analyst, 1964, 89, 775.435 C. L. Newberry and G. D. Christian, J. Electroandyt. Chem., 1965, 9, 468.486 C. Macchi, J . Electroanalyt. Chem., 1965, 9, 290.m7 P. Emmott, Talanta, 1965, l2, 651.4s8 S. P. Perone and W. J. Kretlow, Analyt. Chem., 1965, 37, 968.43D V . A. Mirkin, Zauodskaya Lab., 1965, 81, 395.440 B. H6nin and R. Rosset, Bull. SOC. chim. Prance, 1964, 2250.1965, 37, 1446J . B . HEADRIDGE, T. B. PIERCE, D . M . W. ANDERSON 539Controlled-potential coulometry has been applied to the determination ofwater using Karl Fischer reagent. Iodide produced by the stoicheiometricreaction of water with Karl Fischer reagent is determined coulometrically.MlControlled-potential coulometry has also been used for the determination oftin in glass, brass, and ore concentrate^,"^^ of milligram amounts of plu-tonium(m) in sulphuric acid solution,443 and of millimolar amounts ofamericium(vr) ?4410.R,adiochemistry.-The first part of this section is devoted to theapplication of pre-produced radioactive isotopes to analysis, the second toactivation procedures. Only the direct applications of isotopes to analyticaldeterminations have been included; the uses of radiotracers to obtain dis-tribution or other data which may subsequently be used to devise analyticalmethods have not been considered.144Ce has been determined by isotope dilution invegetable material using 139Ce as diluting isotope, and the effects of chemicalyield and isotope ratio evaluated.445 85Sr additions have been recommendedas a means of making yield determinations for assay of sgSr and 90Sr,446 andthe use of substoicheiometry as a means of analysing radioactive preparationshas been outlined.**' The operation of substoicheiometric isotope dilutionon a continuous basis has also been proposed.44s Niobium has been deter-mined in the range 0-5-150 p.p.m.using g5Nb to assess the chemical yield,449and a new method for plotting results from radiometric exchange reactionshas been suggested.450 Determination of carbon-lithium bonds in lithium-terminated polymers has been carried out radiochemically by measuring theproduct of the reaction with tritiated alc0hols,45~ and the reaction of dichro-mate ions with silver according to the equationCk20,2- + 6Ag + 14H+-+6Ag+ + 2Crs+ + 7H,Ohas been applied to the measurement of dichromate ions in natural waters,measuring liberated 110mAg.452Absolute counting of radionuclides by a B-y coincidence method using aliquid scintillator as internal /3-detector has been discussed in detai1,453 anda reproducibility of s0.274 for counting 01- and p-emitters of an energygreater than 150 Kev has been claimed for a liquid scintillation methodbased on extrapolation of the integral spectrum t o zero energy.*" Several4a1G.A. Rechnitz and K. Srinivasan, 2. analyt. Chm., 1965, 210, 9.442 W. M. Wise and J. I?. Williams, Anal@. Chem., 1965, 37, 1292.443 G. C. Goode and J. Herrington, Analyt.Chim. Acta, 1965, 33, 413.444 G. Koehly, Analyt. Chim. Acta, 1965, 33, 418.446 L. A. Currie, G. M. France, and H. L. Steinberg, Internat. J . Appl. Radiation446 D. M. Keefer, L. F. Edmondson, and R. E. Isaacks, Health Physics, 1965, 11,447 J. RGiiEka, Coll. Czech. Chem. Comm., 1965, 30, 1808.448 J. Riiiii5ka and M. Williams, Talanta, 1965, 12, 967.449 J. Esson, Analyst, 1965, 90, 488.450 J. van R. Smit, Analyst, 1965, 90, 366.461 D. R. Campbell and W. C. Warner, AnaZyt. Chem., 1965, 37, 276.452 H. G. Richter and A. S. Gillespie, jun., Analyt. Chem., 1965, 37, 1146.453 G. Erdtmann and G. Herrmann, Internat. J. Appl. Radiation Isotopes, 1965,464 R. Vaninbroukx and A. Spernol, Internat. J . AppE. Radiation Isotopes, 1965,Isotope techniques.Isotopes, 1965, 16, 1.193.16, 301.16, 289540 ANALYTICAL CHEMISTRYmethods of counting blood samples by liquid scintillation have been coiii-pared,455 and a method for the liquid scintillation counting of l4C in aqueousdigests of whole tissues disc~ssed.~~6 A new method of colour quenchcorrection in liquid scintillation systems, using an isolated internal standard,has been pr0posed,4~7 liquid scintillation counting of emulsions has beencarried out to measure low-energy B-emitters in aqueous solution,458 andeight liquid scintillation systems have been evaluated for counting radio-iodine .459Many Papers have appeared on the subject ofactivation analysis during the year, and advances have been reviewed.460The y-ray photopeak yields have been determined experimentally for 118reactor thermal-neutron products,461 and the use of a single comparatorinstead of a number of standards, one for each element to be determined, hasbeen critically evaluated.462 A pulsed reactor system (peak flux 4.5 x 1016n/cm.2, pulse width at half maximum 15 m.sec.) has been shown to improvethe limits of detection of short-lived activities (ti < 50 ~ e c . ) , 4 ~ ~ the use offast neutron fluxes available in reactor cores has been assessed as a means ofdetermining 35 elements,464 and the relative importance of radioactive capture,inelastic neutron scattering, photoexcitation, and (n,2n) reactions comparedfor the production of a number of metastable isomers suitable for activationanalysis.465 X-Ray fluorescence and neutron activation results for zinc ingeochemical standards have been and other geochemical orcosmochemical determinations by neutron activation include bromine con-tent and isotopic content of bromine in stony meteorites,467 chlorine in stonymeteorites,468 40Ar content of iron meteorites,469 and ~candium,~70 c0pper,~71and rhenium and osmium 472 in a variety of matrices.30 trace elements have been determined simultaneously in cancerous andnon-cancerous human tissue by neutron activation,473 as also have strontiumActivation analysis.4 5 5 A.C. Houtman, Internat. J . Appl. Radiation Isotopes, 1965, 16, 65.456 R. Tye and J. D. Engel, Analyt. Chern., 1965, 37, 1225.4 b 7 H. H. Ross, Analyt. Chem., 1965, 37, 621.458 M. S.Patterson and R. C. Greene, Analyt. Chein., 1965, 37, 854.450 B. A. Rhodes, Analyt. Chem., 1965, 37, 995.460 F. Girardi, Talanta, 1965, 12, 1017; V. P. Guinn, Progress in Nuclear Energy,461 H. P. Yule, Analyt. Chem., 1965, 37, 129.462 F. Girardi, G. Guzzi, and J. Pauly, Analyt. Chem., 1965, 37, 1085.463 H. R. Lukens, jun., H. P. Yule, and V. P. Guinn, Nuclear Instruments and464 H. R. Yule, H;. R. Lukens, jun., and V. P. Guinn, Nuclear Instruments ajzd465 H. M. Kramer and W. H. Wahl, Nuclear Scieiace and Eizgineering, 1965, 22, 373.466 T. K. Ball and R. H. Filby, Geochiinica et Cosrnochinzica Acta, 1965, 29, 737.467 A. Wyttenbach, H. R. von Gunten, and W. Scherle, Geochimica et Cosmochinaiccr468 H. R. von Gunten, A. Wyttenbach, and W. Scherle, Geochimica et Cosmochimica460 R.E. Fisher, J . Geophysical Research, 1965, 70, 2445.47* H. Hamftguchi, T. Watanabe, N. Onuma, K. Tomura, and R. Kuroda, Analyt.471 J. R. Kline, Diss. A h . , 1965, 26, 582.472 J. W. Morgan, Analyt. Chim. Acta, 1965, 32, 8.473 K. Samsahl, D. Brune, and P. 0. Western, Internat. J . Appl. Radiation Isotopes,Series IX, vol. 4, part 2, p. 73.Methods, 1965, 33, 273.Methods, 1965, 33, 277.Acta, 1965, 29, 467.Acta, 1965, 29, 475.Chim. Acta, 1965, 33, 13.1965, 16, 273J . B . HEADRIDGE, T. B. PIERCE, D. BI. w. ANDERSOS 541in environmental media,474 and molybdenum in Neutron activationhas also been used to determine magnesium in needle-biopsy samples ofmuscle tissue, and the sensitivity of the method is estimated as 0.3 pg.476Non-destructive methods for the determination of copper 47 7 and silverand antimony 478 in bismuth have been gased on y-y coincidence measure-ments, sulphur and calcium have been measured non-destructively by photoneutron countingtp79 and a crystal with a thin beryllium window recom-mended for niobium determinati0ns.4~~17 elements have been assayed in polyethylene by y-spectrometry afterreactor irradiation,4*1 and the distribution of some elements in zone-refinedaluminium found by analysing drillings from the ingot by neutron activationSubstoicheiometric finishes to activation procedures have been proposedforGermanium counters have been used to permit easier calculation of y-lineintensities from spectra, recorded during activation and acompufer programme has been described based on the peak area methodwhich has been used for the routine determination of selected elements inmeteorites and separated meteoritic materials.488Work has continued to develop the applications of neutron generators ;analytical applications have been reviewed,489 the performance of a sealed-tube generator has been described,4B0 and the y-spectra of 37 elementsirradiated with 14 Mev neutrons have been publi~hed.4~1 An automatedsystem has been used to determine oxygen in chondrites, aehondrites, andgeochemical and oxygen has also been determined in ezesium ;493the effect of recoiling nuclei from activation of the atmosphere surroundingthe sample vial was found to be proportional to the surface area in contactwith air during the irradiation.Silicon 494 and rare earths 495 have beencopper and si1ver,4s4 c0pper,6~~ and474 P. J. Magno and F. E. Knowles, jun., AnaZyt. Chem., 1965, 37, 1113.476 W. B, Healy and L. C. Bate, Analyt. Chim. Acta, 1965, 33, 443.476 D. Brune and H. E. Sjoberg, AnaZyt. Clzim. Acta, 1965, 33, 570.477 J. I. Kim, A. Speecke, and J. Hoste, AnaZyt. Chim. Acta, 1965, 33, 123.478 J. I. Kim and J. Hoste, Analyt. Chim. Acta, 1965, 33, 449.478 S. Amiel and J. 0. Juliano, Analyt. Chem., 1965, 37, 343.480 A. A. Verbeek, Alzalyt. Chim. Acta, 1965, 33, 131.4s1H. Sorantin and P. Patek, 2. analyt. Chem., 1965, 211, 99.482 D. Gelli, R. Malvano, and G. B. Fasolo, Applied Materials Research, 1965, 4,107.48s J. Rb?;i5ka, A.Zeman, and I. Obrusnik, TaZanta, 1965, 12, 401.lls4N. Suzuki and K. Kudo, AnuZyt. Chim. Acta, 1965, 32, 456.485 M. Ki;iv&nek, F. Kukula, and J. Slune6ko, Tahnta, 1965, 12, 721.IE6 D. A. Beardsley, G. B. Briscoe, J. RbiMka, and 3%. Williams, Talanta, 1965,12, 829.487 S. G. Prussin, J. A. Harris, and J. M. Hollander, Analyt. Chem., 1965, 37, 1127;T. B. Pierce, P. F. Peck, W. M. Henry, and B. W. Hooton, Analyt. Chim, Acta, 1965,33, 586.488 S. C. Choy and R. A. Schmitt, Nature, 1965, 205, 758.48e J, E. Strain, Progress in Nuclear Energy, Series IX, vol. 4, part 3, p. 139.4e0 J. E. Bounden, P. D. Lomer, and J. D. L. H. Wood, Nuclear Instruments andlol Y. Kusaka, H. Tsuji, I. Fujii, H. Muto, and K. Miyoshi, Bull. Chsrn. 800.408 J, R. Vogt and W. D.Ehmann, Radiochina. Acta, 1965, 4, 24.498 0. U. Anders and D. W. Briden, Analyt. Chem, 1965, 37, 530.4 @ p J. R. Vogt and W. D. Ehniann, Qeochinaiea et Cosmochinzica Aeta, 1965, 29, 373.4,DS SL P. Menon and 35. Y . Cuypers, Analyt. Chem., 1965, 37, 1057.Methods, 1965, 33, 283.Japan, 1965, 38, 616542 ANALYTICAL CHEMISTRYdetermined after irradiation with 14 MeV neutrons, and a special study hasbeen made of the factors affecting precision of activation with 14 Mevneutrons.496Interest has been sustained in 3He activation; the scope of the techniquehas been reviewed497 and methods for carbon, oxygen, and fluorine dis-cussed.498 Surface analyses have been carried out with a-particles employinga 24Wm source and a silicon detector.499 Measurement of the 3-09 Mev y-lineemitted during the de-excitation of l3C formed by the reaction W(d,p)13Chaa been used as the basis of a method for the determination of carbon insteel.500 Reactions induced by secondary particles have also been applied toanalytical determinatiom.The sequence %i(n,cc)T, 1sO(t,n)18E” has beenused to determine surface oxygen on metals 501 and lithium in the presenceof alkali metals and magnesiurn,5O2 whilst recoil protons have been appliedto the measurement of the isotopic abundance of oxygen-1€L50311. MSSS Spectrometry.-Damoth504 has published a Review of recentadvances in time-of-flight mass spectrometry, and computer programmeshave been used to obtain the data, on ordered exact mass and abundance,praented in two important papers 505 on the interpretation of mass spectra.A number of interesting contributions dealt with aspects of instrumenta-tion.Cryosorption pumping is claimed to lead to a significant increasein the analytical performance of spark-source mass spectrometry, and asimplified vacuum lock for the direct insertion of mmples has been devised.607Brion 508 has described a windowless photo-ionisation source for high-resolu-tion work, and LincolnSOg has reported that flash-vapourisation massspectrometry offers advantages in the analysis of polymers and some in-organic compounds.Mass spectrometers were used in conjunction with other techniques in anumber of investigations, e.g., differential thermal analysis,510 gas evolutionanalysis ,511 and vacuum fusion analysis of metala.512 Fast -scanning, high-resolution mass spectrometers have been used 513 by several groups of inves-tigators €or the analysis of gas-chromatographic effluents.498 W.E. Mott and J. M. Orange, AnaZyt. Chem., 1965, 37, 1338.497 E. Ricci and R. L. Hahn, AnaZyt. CTiem., 1965, 37, 742.498 J. D. Mahony, Dks. Abs., 1966, 26, 663.40° J. H. Patterson, A. L. Turkevitch, and E. Franzgrote, J . Qwphyaical Research,boo T. B. Pierce, P. F. Peck, and W. M. Henry, Analyst, 1965, 90, 339.5 0 1 W. Leonhwdt, Andyt. Chim. Acta, 1966, 32, 355.602 G. W. Smith, D. J. Santelli, and H. Fiess, Analyt. Chim. Acta, 1965, 33, 1.Sos L. H. Hunt and W. W. Miller, Analyt. Chena., 1965, 37, 1269; D. C. Aumann604 D. C. Damoth, Adv. Analyt.Chem. Instrumn., 1965, 4, 371.605 D. D. Tunnicliff, P. A. Wadsworth, and D. 0. Schissler, Analyt. Chem., 1965,606 W. L. Harrington, R. K. Skogerboe, and G. H. Morrison, Anolyt. Chem., 1965,607 G. A. Junk and H. J. Svec, Anulyt. Chem., 1965, 37, 1629.608 C. E. Brion, Analyt. Chem., 1965, 37, 1706.60D K. A. Lincoln, AnaZyt. Chem., 1965, 37, 641.6loH. G. Langer, R. S. Gohlke, and D. H. Smith, AnaZyt. Chem., 1965, 37, 433.sllW. W. Wendlandt and T. M. Southern, Analyt. Chim. Acta, 1965, 32, 405.sl*R. J. Conzemius and H. J. Svec, Alzcrlyt. Chim. Acta, 1965, 33, 145.6x8 R. Ryhage, S. Wikstrom, and G. R. Waller, AnuZyt. Chem., 1965, 37, 435; J. T.Watson and K. Biemann, ibid., p. 844; C. Merritt, jun., I?. Issenberg, M. L. Bazhet,1965, 70, 1311.and H.J. Born, Internat. J . Appl. Radiation Isotopes, 1965, 16, 727.37, 643; D. D. Tunniclif!f and P. A. Wadsworth, ibid., p. 1082.37, 1480J . B . HEADRIDGE, T . B . PIERCE, D . M. W . ANDERSON 543McFadden et ~ 1 . 5 1 4 have published correlations and anomalies arisingfrom the mass spectra for 46 aliphatic thioesters and 17 lactones. Beckeyhas shown that, for mass-spectrometric analyses of solid natural products,the field ionisation method can be applied in addition to the electron impactmethod. Methyloximes have been used 516 as carbonyl derivatives for massspectrometry, and Russian workers 517 have continued their studies ofcarbohydrates. Sub-nanogram analyses of iodine have been achieved 518by using an ion-source that generates ions by sputtering, and methods havebeen developed 519 to determine 1 volume per million of helium in nitrogen,3 v.p,m.carbon dioxide in hydrogen, and 20 v.p.m. hydrogen in helium.12. Thermal Methods.-Fewer papers on thermal methods appearedin 1965 than in the previous year.Differential thermal analysis and its applications have been re~iewed,~~Oand the thermoanalytical properties of rubidium 521 and czesium 522 saltsreported. A micro-cell for differential thermal analysis 523 and an apparatusfor d.t.a. capable of working a t up to 1500" 524 have been described. Inconnexion with differential thermal analysis, a aample container has beendeveloped for measuring temperature and pressure changes up to 300 p.5.i.g.a t 500 * .525 Differential thermal analysis using high-frequency electricalfields has been applied to the study of curing reactions in rubbers andA technique named continuous flow enthalpimetry has been developedfor routine quantitative chemical analysis, on-line control of processes, andthe measurement of heats of reactions.527 The technique consists in passingtwo reacting solutions through a mixing vessel, the reagent solution beingin excess of the sample solution, and determining the concentration of theweaker sample solution as a result of the temperature change.13.Reaction-Rate Methods.-A simple computer circuit for automaticspectrophotometric analysis of binary mixtures by differential reaction rateahas been descrjbed.s28 Details have been published of a digital readoutpH-stat for obtaining quantitative results from reaction rate informationduring the initial stages of a rea~tion.6~~ The instrument has been employedfor the rapid determination of urea and glucose.B.N. Green, T. 0. Merron, and J. G. Murray, ibid., p. 1037; J. W. Amy, E, M. ChaihW. E. Baitinger, and F. W. McLafferty, ibid., p. 1265.614 W. H. McFadden, E. A. Day, and M. J. Diamond, Analyt. Chem., 1965, 37,89; W. H. McFadden, R. M. Seifert, and J. Urasserman, ibid., p. 560.616 H. D. Beckey, 2. analyt. Chem., 1965, 207, 99.616 H. M. Fales and T. Luukkainen, Analyt. Chem., 1965, 37, 955.617 N. K. Kochetkov, N. S. Vulfson, 0. S. Chizhov, and B. M. Zolotarev, Izvest.618 J. A. McHugh and J. C. Sheffield, dnalyt. Chem., 1965, 57, 1099.619 R. T. Parkinson and L.Toft, Analyst, 1965, 90, 220.s20A. Pande, Lab. Practice, 1965, 14, 566, 832, 938 and 1048.521 L. Erdey, G. Liptay, and S. Ghl, TaEunta, 1965, 12, 883.5 2 2 L. Erdey, G. Liptay, and S. Ghl, Talanta, 1965, 12, 257.623 S. Tanake, Bull. Chem. Soc. Japan, 1965, 38, 795.624 M. M. Hopkins, Rev. Sci. Imtr., 1964, 35, 1658.626 D. J. David, Anulyt. Chem., 1965, 37, 82.626 S. A. Wald and C. C. Winding, Analyt. Chern., 1965, 37, 1622.587 P. T. Priestley, W. S. Sebborn, and R. F. W. Selman, Andy&, 1965, 90, 689.629 H. V. Malmstadt and E. H. Piepmeier, Analyt. Chem., 1965, 37, 34.Akud. Nauk S.S.S.R., Ser. Khim., 1965, 776.D. Pinkel and H. B. Mark, jun., Tulunta, 1966, 12, 491544 AXALYTICAL CHEMISTRYAn automatic spectrophotometric method has been developed for thedetermination of galactose in blood and plasma.530 The method is based onthe action of galactose oxidase on galactose with the production of hydrogenperoxide.The rate of formation of the coloured product formed by reactionof the hydrogen peroxide with o-dianisidine in the presence of peroxidaseis related to the galactose concentration.Very small quantities of cholinesterase have been determined by a reac-tion-rate method based on the hydrolysis by cholinesterase of non-fluorescentresorufin butyrate and indoxylacetate to the fluorescent resorufin and in-doxy1 respectively.531 A reaction-rate method based on fluorescent resorufinhas also been described for measuring the activity of various dehydrogenases,namely lactic acid, alcohol, maleic acid, glutamic acid, glucose-6-phosphate,L- cc-glycerophosphate, and glycerol dehydrogenase~.~~~Ultratrace amounts ( 10-6~-10-10~) of metal ions have been determinedusing co-ordination chain reactions.The rate of the exchange reaction isdependent on the concentration of a free ligand, and the addition of traceamounts of metal ion alters this free ligand concentration.53314. Miscellaneous.-The r6le of the analyst in the pharmaceuticalindustry has been discussed.5aDangers associated with the unguarded use of ‘‘ high purity ” spectro-graphically analysed standards have been stressed.535 Eichholz et al. haveexamined the adsorption of ions on to glass and plastic surfaces from diluteaqueous solutions. It was concluded that, for most elements, the totaladsorption on glassware is so low that it can probably be neglected in themajority of radiochemical and trace analyses.536andrhenium,538 on methods for the detection and quantitative determination ofpesti~ides,5~~ on problems of sampling and sample preparationYu0 and onthe analytical properties and applications of chelating resins.541 Reviewshave also appeared on the quantitative analysis of solid mixtures by diffusereflectance measurement~~~4~ on the principles and analytical applications ofthe Faraday effect , magnetic rotatory dispersion and magnetic circulardichr0ism,~4~ on the applications of radio-frequency methods in analytical~hernistry,5~~ on the electrochemistry of cation-sensitive glass electrodes,545Reviews have been published on the determination of630 C.S. Frings and H. L. Pardue, Analyt. Chem., 1964, 36, 2477.531 G. G. Guilbault and D. N. Kramer, Analyt. Chem., 1965, 37, 120.632 G. G. Guilbault and D. N. Kramer, Analyt. Chem., 1965, 37, 1219.633 D. W. Margerum and R. K. Steinhaus, AnaZyt. Chem., 1965, 37, 222.634 D. C. Garratt, Proc. Soc. Analyt. Chern., 1965, 2, 55.635 S. S. Yamamura, Analyt. Chem., 1964, 36, 2515.536 G. G. Eichholz, A. E. Nagel, and R. B. Hughes, AnaZyt. Chenz., 1965, 31,637 Yu. G. Eremin, L. A. Lavrova, V. V. Raevskaya, and P. N. Romanov, Zat+ocEskya53BV. M. Tarayan and S. V. Vartanyan, Zavodskaya Lab., 1964, 30, 1301.63e I. K. Isitovich, Zhur. analit. Khim., 1965, 20, 875.& a o H. Sporbeck, 2. analyt. Chem., 1965, 209, 60.541 G.Schmuckler, Talanta, 1965, 12, 281.642 W. P. Doyle and F. Forbes, Analyt. C h h . Acta, 1965, 33, 108.543 J. G. Dawber, Analyst, 1964, 89, 755.544 M. F. C. Ladd and W. H. Lee, Talanta, 1965, 12, 941.5 4 5 G. Eisenman, Adv. Analyt. Chern. Instrument., 1965, 4, 213.863.Lab., 1964, 30, 1427J . B. HEADRIDGE, T . B. PIERCE, D . M. W. ANDERSON 545on phase-solubility techniq~es,~4~ on the analytical applications of differen-tial dialysis,5*7 and on recent developments in kinetic methods of analysis.548It is reported that hydrofluoric acid alone is the most effective reagentfor decomposing the minerals of silicate rocks. Many are decomposed byheating on the water-bath, while most others are decomposed at the highertemperatures available with a Teflon-lined b0mb.54~ The decomposition ofrocks, refractory silicates, and minerals is rapid and complete, if the materialis fused with a mixture of lithium fluoride and boric acid at about 800-8.50"in a platinum crucible.550A computer programme has been devised for identifying crystallinephases by powder diffra~tion.~~l Gleit 552 has developed a high-frequencyelectrodeless discharge system for ashing organic matter, and a condensat'ionpressure analyser has been described for the continuous determination ofuranium hexafluoride in a gaseous plant stream.553 The deuterium oxidecontent of water has been rapidly determined using a vapour-pressureosmometer.554 Chemical microscopy has been applied to the analysis ofurinary calculi.555Edge and Fowles have reported that titanium(Iv), vanadium( v), molyb-denum(vr), and iron(m) are quantitatively reduced to the 3 + , 2 + , 3 + ,and 2+ states respectively with sodium-lead alloy in acid solution.Thereducing action of the alloy is similar to that of zinc amalgam.556Cerium(rv), permanganate, and iron(ri1) in the micromolar concentrationrange have been determined by chemical stripping analysis where silver isoxidised from a rotating platinum electrode. From a plot of electrodepotential versus time, the time required to oxidise a known amount of silveris determined. This time is inversely proportional to the concentration ofoxidant in the s0lution.~57An automatic method for supplying the result in three minutes has beenapplied to the determination of phosphorus in copper. The metal is dis-solved by constant-current anodic oxidation and the phosphate determinedphotometrically with molybdovanadate reagent. The method should beapplicable to the analysis of other elements in other metal~.5~*Direct measurement of the e.m.f. of a concentration cell, with the elec-trodes consisting of thin silver rods submerged in a suspension of the cor-responding silver halide in dilute acid, has been employed for the satisfactorydetermination of small amounts of halide ions in solution. The method wasapplied to the determination of chlorine in organochlorine compounds after546 T. Higuchi and K. A. Connors, A h . Analyt. Chem. Instrument., 1965, 4, 117.547 L. C. Graig, Adv. Analyt. Chem. Instrument, 1965, 4, 35.518 K. B. Yatsimirskii, V. K. Povlova, and V. I. Skuratov, Zacodskaya Lab., 1965,549 F. 5. Langmyhr and S. Sveen, Analyt. Chim. Acta, 1965, 32, 1.550 V. S. Biskupsky, Analyt. Chim. Acta, 1965, 33, 333.551 L. K. Frevel, Analyt. Chem., 1966, 37, 471.552 C. E. Gleit, Analyt. Chem., 1965, 37, 314.553 W. S. Pappas and C. W. Weber, Analyt. Chem., 1965, 37, 407.554 E. Lazzarini, Nature, 1964, 204, 875.555 D. E. Laskowski, Analyt. Chern., 1965, 87, 1399.556 R. A. Edge and G. W. A. Fowles, Analyt. Chim. Acta, 1965, 32, 191.s57 S. Bruckenstein and J. W. Bixler, Analyt. Chem., 1965, 37, 786.658 8. Barabas and 6. G. Lea, Analyt. Chem., 1965, 37, 1132.31, 525546 ANALYTICAL CHEMISTRYoxygen-flask comb~stion.~~g Potentiometric measurements using a cationicsensitive glass electrode have been used to determine the concentration ofammonium ion in a trishydroxymethylaminomethane buffer at pH 7.0.The method was applied for determining urease activity from the amount ofammonium ion formed within a given period of time by the action of theenzyme on urea.56o A sensitive Clark-type electrode for use with samples assmall as 0.3 ml. has been constructed for measurement of oxygen concentra-tion in solutions.5G1A technique of spot electrolysis has been proposed for the determinationof 5-20 nanoequivalents of oxidisible or reducible ions. A spot of material,produced on an inert electrode by evaporation from aqueous solution, isbrought into contact with a supporting electrolyte and immediately elec-trolysed. The resulting current is a function of the quantity of electroactivematerial in the sp0t.5~~A new electroanalytical technique, phase angle titration, has been des-cribed. When a constant alternating current is applied between two plati-num electrodes immersed in a reversible redox system, the relative phaseangle between current and voltage varies as the concentration of the reduciblespecies changes on titration with an oxidising agent. A large change inphase angle occurs at the end-point of the titration. The precisions of titra-tions are excellent even for O~OO1~-solutions.~~~Reviews have been published on the determination of oxygen in metalsand inorganic compounds by reduction fusion in an inert gas atmo~phere,5~4and on the determination of gases in metals by vacuum fusion, by fusion inan atmosphere of inert carrier gas, and by isotopic ex~hange.5~6 The ther-modynamic principles of determining gases in metals by the vacuum fusionmethod have been examined, and equations derived to find the optimumconditions for applying this techniq~e.5~6 Lemm has described a fa& methodfor the determination of nitrogen in steel by carrier-gas extraction,s67 and avacuum melting instrument for the rapid and accurate determination ofoxygen, hydrogen, and nitrogen in metals without separation of the gaseshas been constructed.56* The Zaidel isotopic balancing spectroscopicmethod has been applied to the determination of hydrogen in uranium metal.The relative error was 3-7% for hydrogen contents between 0.5 and 5p . ~ . m . 5 ~ ~ Carbon in sodium in the range 3-12 p.p.m. has been determinedby removing the sodium by distillation at 600°, converting the carbon in theresidue into carbon dioxide by combustion in an excess of oxygen, andmeasuring the carbon dioxide manornetri~ally.~7~650 J. Roburn, Analyst, 1965, 90, 467.560 S. A. Katz, Analyt. Chem., 1964, 36, 2500.s 6 1 J. S. Kahn, AnaEyt. Biochem., 1964, 9, 389.562 D. H. Evans, Analyt. Chem., 1965, 37, 1520.5133 U. H. Narayanan, G. Dorairaj, and Y. M. Iyer, J . Electroandyt. Chem., 1964,564 A. M. Vasserman and Z. M. Turovtseva, Zhur. analit. Khim., 1964, 19, 1377.565Yu. A. Karpov and G. G. Glavin, Zavodskaya Lab., 1965, 81, 139.s66 L. L. Kunin, Zhur. analit. Khim., 1965, 20, 822.567 H. Lemm, 2. analyt. Chem., 1965, 209, 114.s68T. Kraus, 2. analyt. Chern., 1965, 209, 206.560 H. Kawaguchi, Japan Analyst, 1965, 14, 138.570 J. A. J. Walker and E. D. France, Analyst, 1965, 90, 228.8, 472

ISSN:0365-6217    

DOI:10.1039/AR9656200511

出版商:RSC    

年代:1965

数据来源: RSC

摘要:

CRYSTALLOGRAPHYBy H. 1. Powell, C. E. Rout, and 8. C. Wallwork(H. &I. P. & C. K. P.: Chemical Crystallography Laboratory,South Park8 Road, Oxford:and S . C. W.: Chemistry Department, The Umiversity, Nottingham)1. INTRODUCTIONTHE number of new crystal structures appearing each year rises very rapidly.Papers scrutinised for this report were well over 50% more than those for thclast. This section is therefore severely limited. General articles or reviewshave appeared on X-ray ana.lysis of proteins,l natural productsYand com-plicated molecules.3 A new stage reached in the application of X-raydiffraction t o chemical problems must be mentioned. It is the first deter-mination of the structures of a crystalline enzyme, ly~ozyme.~ Closelyrelated work on lysozyme inhibitor complexes 5 shows how crystallographicstudies lead to conclusions concerning the way in which competitiveinhibitors of lysozyme may act, and thus reveal which part of the complexlysozyme molecule may be responsible for its enzymatic activity.Extensivedevelopments are to be expected.2. INOBUANIC AND OBGCANOMETALLIC COMPOUNDSBinary and Ternary Compounds,--SimpZe and mixed oxides and oxy-acidsalts. A neutron and X-ray diffraction analysis of single crystals of yttria,sY,Oa, confirms the earlier analysis based on X-ray powder data. Withinthe yttrium co-ordination polyhedron Y-0 distances of 2.260, 2.278, and2.354. A were observed. The crystal structure of the tetragonal p-berylliais related to rutile with the same configuration of metal atoms about oxygenbut with the beryllium atoms in a tetrahedral environment of oxygen atoms.Thescandium atoms are of two types; both are a t the centres of distortedoctahedra of oxygen atoms, d(Sc-0) = 2.04-2.22 A. The calcium ionshave distorted square antiprism eight-co-ordination.It is surprising that alarge number of barium mixed oxide^,^ Ba,MO, (M = Ti, V, Cr, Mn, Fe,Co, Ge, and Si), Ba2LaM05 (M = Fey Co, Al, and Ga), and mixed strontiumoxides Sr,LnAlO, and Sr,LaGaO,, are reported to be isostructural withCs,CoCl,. Ca&un aluminate,1° CsAlO,, like the rubidium salt but unlikethe sodium and potassium salts, has an arrangement of NO, tetrahedra,Calcium scandium oxideYs CaSc,O,, is an isotype of CaFe204.L. Bragg, R e p d s Progr. Phys., 1966, 28, 1.J.M. Robertson, Pure Appl. Chm., 1964, 9, 179.3D. C. Hodgkin, Angew. Chem., 1966, 77, 954.C. C. F. Blake, D. F. Koenig, G. A. Mair, A. C. T. North, D. C. Phillips, and V. R.L. M. Johnson and D. C. Phillips, Nature, 1965, 208, 761.M. G. Paton and E. N. Mash, Acia Cqst., 1966, 19, 307.D. K. Smith and C. F. Cline, A& Cqst., 1965, 18, 393.Sarma, Nature, 1965, 206, 757.* H. Muller-Buschbaum and H. G. Sobering, 2. anorg. Ohm., 1966, 888, 295.DM. M a n s m , 2. anorg. Chern., 1965, 339, 52.lo G. Langlet, Compt. rend., 1964, 259, 3769848 CRYSTALLOGRAPHYsimilar to that found in crystobalite, and resembles barium cadmate,BaCdO,. Zinc aluminate,ll in contrast, has a well ordered ‘’ normal ” spinelstructure. The zinc atoms occupy tetrahedral holes, d(Zn-0) = 1-88 A,and aluminium atoms octahedral holes, d(A1-0) = 1-96 A, in a close packedoxygen array.Lithium gallate, LiGaO ,,I2 forms a Wurtzite-like structureand is an isotype of NaFeO,. Cadmium germanate13 has an olivine-likestructure. A large number of silicide and germanide chalcogenides ofzirconium and hafnium are PbFC1 is0types.1~ This includes ZrSiO( S,Se),HfSiO(S,Se), ZrGeO(S,Se), and HfGeO(S,Se). A recent redeterminationhas confirmed the 1959 analysis of the structure of baddeleyiteI5 (mono-clinic ZrO,). Ulvospinel,16 TiFe,O,, has been studied by neutron andX-ray techniques. The titanium Ti4+ ions tend to occupy the octahedralB sites rather than the tetrahedral A sites. The ordering is not complete;the degree of inversion is 0.92.Zinc orthotitanate,l7 Zn(ZnTi)O,, is aninverse spinel. VLiCu04 18 is also a spinel with vanadium in tetrahedral,and lithium and copper in octahedral sites. In lithium vanadium bronze,lgLiV,O,, each vanadium atom is surrounded by five oxygen atoms at thecorners of a trigonal bipyramid. The trigonal bipyramids, associated inpairs by sharing a common edge, form chains. Lithium atoms in octahedralsites effect cohesion between the chains. Isolated VO, tetrahedra are foundin Th,(V0,)4,20 which is an isotype of the lanthanide vanadates LVO, butwith ordered vacancies among the metal ion sites.The [-Nb20, phase21 is reported as having hexagonal close packedoxygen atoms with two-fifths of the octahedral holes filled with niobiumatoms in a regular array, d(Nb-0) = 1-81-2.12 8.Other phases of boththe simple and mixed oxide type with stoicheiometry approaching that ofNb205 have structures built up from Re0,-type structural blocks. A high-temperature form of Nb,O, z2 has endless Re0,-type blocks, three NbO,octahedra wide by five octahedra deep, cemented together by a second kindof endless block, three NbO, octahedra wide and four deep, sharing edgesand leaving symmetrical tetrahedral holes which are partly, but symmetri-cally, filled by niobium atoms. This is the n = 9 homologue of a series ofthe general form Nb3n+108n-2. The n = 8 homologue, Nb2506223 orNbO,.,,, is isostructural with Nb,4Ti0,,.24 The latter has endless Re0,-type blocks, three octahedra wide by four deep, joined together in pairs,and the double blocks packed together by sharing an additional edge. Thel1 H.Saalfeld, 2. Krist., 1964, 120, 476.l2 35. Marezio, Acta Cryst., 1966, 18, 481.13P. Tarte, J . Inorg. Nuclear Chem., 1965, 27, 1933.14 H. Onken, K. Vierheilig, and H. Hahn, 2. anorg. Clienz., 1964, 333, 267.l5 D. K. Smith and H. W. Newkirk, Acta Cryst., 1965, 18, 983.l6 R. H. Forster and E. 0. Hall, Acta Cryst., 1965, 18, 857.1’ Y. Billiet, I. Morgenstern-Badarau, P. Poix, and A. Michel, Compt. rend., 1965,1* J. Galy and A. Hardy, Acta Cry.&, 1965, 19, 432.ao G. Le Flem, A. Hardy, and P. Hagenmuller, Compt. rend., 1965, 260, 1663.2 1 F. Laves, W. Petter, and H. Wulf, Natunoiss., 1964, 51, 633.*2B. M. Gatehouse and A.D. Wadsley, Acta Cryst., 1964, 17, 1545.23 R. Norin, Naturwiss., 1965, 52, 300.24 R. 8. Roth and ,4. D. Wadsley, Acta Cryst., 1965, 18, 724.280, 4780.J. C. Joubert, J.-C. Grenier, and A. Durif, Compt. rend., 1965, 2472H . M . POWELL, C . K . PROUT, S . C . WALLWORK 540titaniuni atoms are in tetrahedral holes at the junctions. W,Nb160,, 25has endless Re0,-type blocks, four octahedra by five deep, with some of thetungsten atoms in tetrahedral holes between every four blocks. The struc-tures of W3Nb,,40,4 and WsNbl,0,9 26 are similar but the blocks are four byfour octahedra and five by five octahedra, respectively. Niobium andtungsten occupy octahedral sites a t random. WN b1,03, has similar ReO,-type blocks, three octahedra by four, wifi all the tungsten atoms on tetra-hedral sites a t the junctions of every four blocks.The “ block principle ’’is discussed with reference to these and other c0mpounds.~7 Endless ReO,-type blocks are also found in PNbgOBB28 and Nb307F.29 In the former theblocks are three octahedra wide and three deep. The blocks are joined tosimilar blocks a t different levels by sharing octahedral edges. The tetrahedralpositions at the junctions are occupied in part by phosphorus atoms whichmay or may not be ordered. In Nb307E’ the blocks are in fact sheets infinitein two directions and limited to three octahedra in the third. Nb,O,Cl 30 isnot isostructural. It has a distorted three-dimensional lattice of NbO ,Cloctahedra, d(Nb-0) = 1.79-2.16 8, d(Nb-C1) = 2.60 A, and Nb06 octa-hedra, d(Nb-0) = 1.75-2-28 8.Each chlorine has two niobium neighbours.In NaNb1@3331 the Nb06 octahedra have edges and corners in common,d(Nb-0) = 1.71-2.40, d(0-0) = 2-62 8, and the sodium ions are a t thecentre of a square plane of oxygen atoms a t 2.60 8. This configuration israrely found in sodium chemistry but has been observed in sodium titaniumdioxide bronze. The homologous series NaM,, is discussed. Thebronze Ba6Ti,Nb,03, 32 has niobium and titanium atoms distribueed sta-tistically throughout the structure and surrounded by octahedra of oxygenatoms. The metal-oxygen octahedra are joined together by corners to forma framework containing four- and five-sided tunnels which run through thestructure. Barium atoms fully occupy all available sites in the tunnels.Thegallium and niobium atoms in GaNbO, 33 occupy distorted octahedral sitessimilar to those found in aluminium and titanium niobates. The structureof B-Tct205 34 is said to have tantalum atoms a t the corners of a hexagonalunit with oxygen in the centres. The tantalum oxygen separations varybetween 1.95 and 2-05 A.Isolated CrO, tetrahedra are found in PbCr0,.35 The lead atoms arefound t o be 7-co-ordinated, d(Pb-0) = 2-53-344; d(Cr-O),, = 1.65 a.Ca,0H(Cr04)3,36 an apatite, also has Cr04 tetrahedra. Cr50123’ has acubic close packed array of oxygen atoms with metal atoms a t the inter-stices. Of these metal atoms, three-fifths, located in tetrahedral holes,25 R. S. Roth and A. D. Wadsley, Acta Cryst., 1965, 19, 32.26 R.S. Roth and A. D. Wadsley, Acta Cryst., 1965, 19, 38.27 R. S. Rotli and A. D. Wadsley, Acta Cryst., 1965, 19, 42.z* R. S. Roth, A. D. Wadsley, and S. Anderson, Acta Cryst., 1965, 18, 643.30 H. G. Schnering and W. Mertin, Naturwiss., 1964, 51, 522.31 S. Andersson, Acta Chern. Scand., 1965, 19, 557.3a N. C. Stephenson, Acta Cryst., 1965, 18, 496.33 B. Morosin and A. Rosenzweig, Acta Cryst., 1965, 18, 874.34 K. Lehovec, J . Less-Conamon Metab, 1964, 7 , 397.35 S. Quareni and R. De Pieri, Acta Cryst., 1965, 19, 287.36 K.-A. Wilhelmi and 0. Jonsson, Acta Chem. Scand., 1965, 19, 177.37 K.-A. Wilhelmi, Acta Chern. Scand., 1965, 19, 165.S. Andersson, Acta Chem. Scand., 1964, 18, 2339550 CRYSTALLOGRAPHYd(Cr-0) = 1.64-1.67, are sexiualent, and two-fifths in octahedral holes,d(Cr-0) = 1-94-1.99 8, are tervalent. The red potassium molybdenumbronze,38 K0.,,M003, has distorted MOO, octahedra grouped by edge sharinginto units of six.These units share corners to form layers with potassiumions in irregular eight-co-ordinate interlayer positions. The unit is similarto those found in hepta- and octa-molybdates and in CoMoO,. In CoMoO, 39both cations are 6-co-ordinated to oxygens in an arrangement of distortedoctahedra based on a rock-salt type structure, in which not all octahedraare occupied. Cations occur only in edge-sharing octahedra so as to formS n i t e chains parallel to the crystallographic c-axis. Each chain of filledoctahedra is surrounded by chains of unfilled octahedra. There are twocrystallographically independent COO, groups, d(Co-0) = 2.30-2-17 and2.01-2.16 8, and two independent MOO, group, d(Mo-0) = 1.73-2.31and 1-72-2-33 A with the molybdenum atom displaced 0.49 8 from thecentre of the octahedron.In MOOPO,,~~ MOO, octahedra are linked inchains by sharing corners and coupled by PO, tetrahedra so that eachMOO, octahedron is sharing corners with four PO4 groups. The PO, groupsare regular but the MOO, groups are distorted so that they might be betterdescribed as MO htragonal pyramids. Lead molybdenum oxide, PbMoO,,41has been shown by a, neutron-diffraction investigation to be a scheeliteisotype. The molybdenum-oxygen distance in each MOO, tetrahedral unitis 1-77 8. Each lead atom is surrounded by eight oxygen atoms of eightMOO, groups, four at 2.610 A and four at 2.630 8.Scandium manganese@@ oxide 42 is an isotype of LuMnO,, Mn,O, is anisotype of Cd&h308,43 and cadmium rhenium oxide, Cd,Re,0,,44 is a mixedoxide of the pyrochlore type.The rhenium-containing mixed oxides offormula A1l,Re&nO,, 45 are layer structures based on close packing of AO,layers. The rhenium and metal (M) are in octahedral sites so that facesharing of Wed M(Re)O, octahedra is avoided by a symmetric arrangementof empty octahedral holes. When A is Ba and M is Mg, Ca, Co, Zn, or Cd,and when A is Sr and M is Mg, Co, Ni, or Zn, the repeat unit is a twelve-layerstack, and for Ba6Re2OI2, Sr,Re,012, Sr,Re,CaO,,, and Sr3Ca&e,01,,that is when M is large, a twenty-four layer repeat unit is found.The oxide CuFeO, 46 is structurally very similar t o NaFeO, and AgFeO,.Gadolinium and yttrium orthoferrates, YFeO, and GaFe0,,47 are perow-skites in which the FeO, octahedron is hardly affected by the perowskitedistortions, It is suggested that the Fe3+-02--Fe3+ angles in relatedperowskites might be predicted from known unit-cell dimensions, assumingthat they also have undistorted FeO, octahedra.The FeO, octahedra are38 N. C. Stephenson and A. D. Wadsley, Ada Cryst., 1965, 19, 241.39 Q. W. Smith and J. A. Ibers, Acta Cryst., 1965, 19, 269.40 P. Kierkegaard and M. Westerlund, Acta Chem. Scand., 1964, 18, 2217.41 J. Leciejewicz, 2. K e t . , 1965, 121, 158.If H. R. Oswald, W. Feitknecht, and M. J. Wampetich, Nature, 1965, 20'7, 72.O * P .C. Donohue, J. M. Longo, R, D. Rosenstein, and L. Katz, Inorg. Chem.,I5 J. M. Longo, L. Katz, and R. Wmd, Inorg. Chem., 1965, 4, 238.R. Norrestam, Acta Chem. Scand., 1965, 19, 1009.1965, 4, 1152.J.-H. Emons and E. Beger, 2. anorg. Chem., 1964, 333, 108.P. Coppens and M. Eibschutz, Acta Cryst., 1965, 19, 524H . M . POWELL, C . R. PROUT, S . C . WALLWOEK 551irregular in the piezoelectric ferromagnetic gallium iron oxides Ga,- ,Fe,03(0.7 < z < 1*4).4* A detailed investigation of the compound with z = 0.97has yielded the absolute configuration and the magnetic spin structure as wellas detailed atomic co-ordinates. The oxygen atoms are pseudo-hexagonalclose packed with double h.c.c. repeat. One gallium atom is a t a regulartetrehedral site, d(Ga-0) = 1.846 8, and a second a t an irregular octahedralsite, d(Ga-O),, = 2.026 A.Gallium atoms of the second type are partlyreplaced by iron. Two iron atoms occupy irregular octahedral sites,d(Fe-0), = 2.030 A and may be replaced by gallium. Barium rutheniumoxide,49 BaRuO,, has close packed BaO, layers in a nine-layer stack. Itsruthenium atoms are at the centres of octahedra which form strings of three,sharing faces. Within theruthenium cluster in the trio of octahedra the Ru-Ru distances is only2.55 A. Manganese w i l l replace ruthenium isomorphously. OsmiumtetroxideY5* OsO,, in the crystal is in the form of isolated OsO, molecules,d(0s-0) = 1.74 A. The shortest intermolecular contact is one from oxygento oxygen of 2.98 A and is consistent with the low melting point and highvapour pressure.The oxide CaIrO,51 has IrO, octahedra sharing edgesand corners to form sheets linked by nine-co-ordinated calcium ions,d(1r-0) = 1-94-2.07 8.The X-ray structure analysis of red lead, Pb304,62 has been confirmedby neutron diffraction methods. Some interatomic distances have beenmeasured. For the lead atoms in octahedral sites d(Pb-0) is 2-14 and 2.13,and for lead atoms in tetragonal pyramidal sites d(Pb-0) on the basal planeis 2.18 and 2.13 and d(Pb-OaPIca1) = 3.01 8. (Pb0,)co chains of Pb06octahedra sharing edges have been found in SrzPb04.53 The strontiumatoms are seven-co-ordinated. The structure is comparable with that ofNumerous basic bismuth salts have been examined.54 Bi,O( OH),S04has [Bi,O(OH)I3+ aggregates forming chains.Bi(OH)SO,H,O andBi( OH)SeO,H ,O have [ Bi,( OH) ,I4+ aggregates similar to those found inBiOHCrO,. Bi(OH)CrO, 55 has square [Bi,0H),I4+ aggregates; oxygenbridges, d(Bi-0) = 2.30 A result in a puckered two-dimensional net ofbismuth atoms in condensed hexagons with Bi-Bi distances of 3.68-4-06 A.There are two crystallographically different forms of essentially the samestructure. Bismuth oxyfluorides6 is niade up of Bi,022+ units and FZ2-groups. Bi( OH)Se04,H20 has bismuth atoms surrounded by nine oxygenatoms, eight in a square antiprism and one outside a square face. A rede-termination of the crystal structure of tellurite (rhombic TeO,) 57 has shownThe strings are linked by corner sharing.N~@3.il?4.S.C. Abrahams, J. M. Reddy, and J. L. Bernstein, J . Chem. Phys., 1965, 42,3957.49 P. C. Donohue, L. Katz, and R. Ward, Inorg. Chem., 1965, 4, 306.50 T. Ueki, A. Zalkin, and D. H. Templeton, Actu Cryst., 1965, 19, 157.61 F. Rodi and D. Babel, 2. anorg. Chem., 1965, 336, 17.63 M. K. Fapk and J. Leciejewicz, 2. anorg. Chem., 1965, 336, 104.63 31. Tromel, Nuturwiss., 1965, 52, 492.64 B. Aurivillius, Acta Chem. Scand., 1964, 18, 2375.56 B. Aurivillius and A. Lowenhielm, Actu Chem. Scand., 1964, 18, 1937.66 B. Aurivillius, Acta Chm. Scand., 1964, 18, 1823.67 H. Beyer, K. Sahl, and 5. Zemann, Nuturwiss., 1965, 52, 155552 CRYSTALLOGRAPHYit to be of the pseudo-brookite form. The uranium atoms in BaU,O, 58 areat the centres of octahedral UO, groups, and within the UO, groups UO,groups are present.These do not take part in the edge-sharing which givesendless chains. The barium atoms are in cubic holes between the chains.The structure analysis of crystals of oxy-acid salts continues actively.Isolated B(OH),- tetrahedra have been observed in LiB(OH),59 and inSb[B(OH),J2.00 The lithium and strontium ions have four and nine oxygenneighbours, respectively. Strontium diborate, SrB,07,61 has a three-dimen-sional network of BO, tetrahedra in which some oxygens are bonded to asmany as three boron atoms. The strontium co-ordination is highly irregular,In contrast, barium tetraborate, BaB,07,62 has a three-dimensional networkformed by the linkage of six-membered single rings (of two BO, tetrahedraand one trigonal planar BO, group) with double rings (of two B0, tetrahedra,one common to each ring, and three BO, planar groups).Each single ringis directly linked only to double rings and each double ring only to singlerings. The Ba2+ ions fit into channels in this network. The borate anion insilver tetraborate, Ag,B80,,,63 consists of two separate identical interpene-trating three-dimensional networks. Each of these is composed of the unitspreviously found in potassium pentaborate and lithium diborate.A new refinement of calcite 64 at 130" K gives a C-0 distance of 1.283with an e.s.d. of 0.002 8. Sodium hydrogen carbonate 65 has also been re-examined. The carbon-oxygen bond lengths of the oxygens not bound tohydrogen are 1.249 and 1.275 A The longer of these is rather more thanthree e.s.d.'s shorter than the C-OH bond of 1.345 A; d(0-H) = 1.07 andd(O.-H) = 1.56, giving a hydrogen bond of length 2.63 A.One form of phyllosilicic acid, H,Si20,,66 is isostructural with Li,Si,O,.Short 0-H-0 hydrogen bonds, 2.65 8, are found and are in accordancewith the low acidity. A new type of silicate sheet containing four-, six- andeight-membered rings of Si04 tetrahedra has been found in dalyite,Kl.7~a,.,,ZrSi,0,,.67 The sheets are joined by Zr06 octahedra and(K,Na)O, polyhedra.There are twelve crystallographically distinct Si-0bonds of lengths 1.54-1.67 A; d(Zr-O),, = 2-06 andd(K,Na-0) = 3.02 A.Threefold endless chains of Si04 tetrahedra linked in pairs by edge sharingand the pairs linked by corner sharing form the (Si,0J4f anion in Ba,Si,08.68Barysilite, MnPb8,3Si,0,,69 and its germanium isomorph contain the iso-lated Si20,6- anion which has a bent Si-0-Si bridge, ,/(Si-0-Si) = 135",in contrast with the linear bridge found in the anion in thortveitite,Sc ,Si 20,.J.G. Allpress, J . Inorg. Nuclear Chem., 1965, 27, 1521.6BE. Hohne, 2. Chem., 1964, 4, 431.eo L. Kutscharsky, 8. Chem., 1965, 5, 110.61 J. Krogh-Moe, Acta Chem. Scand., 1964, 18, 2055.g 2 S. Block and A. Perloff, Acta Cryst., 1965, 19, 297.63 J. Krogh-Moe. Acta Cyst., 1965, 18, 77.6 4 H. Chessin, W. C. Hamilton, and B. Post, Acta Cryst., 1966, 18, 689.6 5 B. D. Shttrmrt, Acta Cyst., 1965, 18, 818.6 a H. Katscher and F.Liebau, Na,turwiss., 1965, 52, 51'7.6s J. Lajerowicz, Compt. rend., 1964, 259, 4248.F. Liebau, 2. Krist., 1964, 120, 427.S. G. Fleet, 2. Krist., 1965, 121, 349H . 31. POWELL, C . K . PROUT, S . C . WALLWORK 553A very careful study of turquoise CuA1,(PO,),(OH),4H2O has beenmade.70 The resulting structure is very complex. The structural unitsare condensed PO, tetrahedra, d(P-0) = 1.521-1*550, A10, ictahedra,d(A1-0) = 1431-2.01, and CuO, octahedra, d(Cu-0) = 1-92, 2.12, and2.42 A. /l-Mg,P207 71 and j3-Zn2P207 72 are isomorphous and are formedfrom isolated P,O,4- ions and metal ions which are octahedrally co-ordinatedwith respect to oxygen.Ring anions P30D3- are found in Na3P30, and Na3P30,H20.73 The twophases have the same structure with respect to oxygen and phosphorusatoms.The ring anions are in the chair form, d(P-O)(bridging) = 1.615,(terminal) = 1.484 8, L(O-P-0) = 101*lo, Thereare two crystallographically distinct sodium ions both five-co-ordinated,one with square pyramidal, the other with a distorted trigonal bipyra-midal arrangement of oxygen neighbours. The amidotriphosphateK4P,O9NH2,4H2O 7* contains P30gNH4- chain anions formed by the join-ing of three tetrahedra by corners, d( P-0) = 1.59-1 -64 for bridging oxygenand 1.44-1.54 ,& for terminal oxygen; d(P-N) = 1-70 8. Three of thepotassium atoms are irregularly surrounded by seven oxygen atoms, and thefourth by six oxygen atoms and a nitrogen. The structure consists of layersof triphosphate ions and potassium ions alternating with layers of watermolecules.Rings formed from six PO4 tetrahedra sharing corners are theanions in Na,(P,0,,)6H,0,75 d(P-0) = 1.60-1.62 (bridging) and 1.48-1-50 ,& (terminal). Cpb(PO,),], 7, contains a new type of chain anion withfour PO4 tetrahedra per period of the chain. The author discusses the formand dimensions of known polyphosphate chains. The structure of hydroxya-patite 7' has been redetermined by neutron diffraction methods.A number of sulphates including celestite, SrS04,78 and anulite,I<A1,(S0,)2(OH),,79 have been examined, and large errors have been foundin the oxygen parameters deduced in earlier works. The structure ofLi,SO,,H,O has been refined. The sulphur-oxygen bond lengths givenin good determinations for a number of sulphates have been corrected forthermal motion.For the ion in Li2S04,H20 the average S-0 distanceis 1.480 A; the individual values are 1.473, 1.473, 1.487, and 1.486 A.Other average values are 1.479 in MgS04,4H,0, 1.486 in PeSO,,'i~,O,1.486 in MgS0,,7R20, and 1.486 8 in Mg(NH4),(S0,),(S0,),,6H20. Adetailed analysis of sodium hydrogen sulphate 81 (cf. NaHCO,) has shownthe SO4 tetrahedron to be distorted, d(S-O),, = 1.45 and d(S-OH) = 1.61 A.The trigonal pyramidal SOS2- ion in (NH4),S0,H,0 82 has a sulphur-,/(P-O-P) == 126.9".' O H . Cid-Dresd-Ner, 2. Krht., 1965, 121, 87.71 C. Calvo, Canad. J . Chem., 1965, 43, 1139.7 2 C. Calvo, Canad. J . Chem., 1965, 43, 1147.53 H. M. Ondik, Acta Cryst., 1965, 18, 226.74 W.Hilmer, Acta Cryst., 1965, 19, 362.75 K. H. Jost, Acta Cryst., 1965, 19, 555.76 K. H. Jost, Acta Cryst., 1964, 17, 1539.7 7 M. I. Kay, R. A. Young, and A. S. Posner, Nature, 1964, 204, 1050.D. G-arske and D. R. Peacor, 2. Krkt., 1965, 121, 204.Rong Wmg, W. F. Bradley, and H. Steinfink, Acta Cryst., 1965, 18, 249.A. C. Larson, Acta Cryst., 1965, 18, 717.SlG. E. Pringle and T . A. Broadbent, Acta Cryst., 1965, 19, 426.L. F. Battelle and K. PIT. Trueblood, Acta Cryst., 1965, 19, 531554 CRYSTALLOGRAPHYoxygen distance of 1.53 8. This provides an example of the increasingbond distance with decreasing oxidation number in oxyanions of the third-row elements, as previously observed for oxyanions of chlorine.A new potassium tellurate, K2Te02(OH),,P3 has chains of TeO, octa-hedra sharing corners and linked by potassium ions.KTeO,(OH) 84 issimilar. Here chains of distorted TeO, octahedra are formed by edgesharing, d(Te-0) = 1.84, 1.96, and 2.0 A.Two (HO)O,I octahedra share an edge to form the dimeric H21,01,4-anion in tetrapotassium dihydrogen decaoxodi-iodate( m) octahydrate,~Z(1-0)~~ = 1.996 bridging and 1.807 A terminal.85Carbides, silicides, phosphides, sulphides, sebnides, and tellurides. Thecrystals of ScB,C, 86 contain a new type of quasi-aromatic network of boronand carbon in five- and seven-membered rings. The scandium atoms liebetween the seven-membered rings of adjacent layers. Each scandium issurrounded by five others at a separation equal to the shortest in scandiummetal.Lithium carbide, Li2C2,*’ is an isotype of Rb,O, and Ct3,02, V,Cand Ta,C 88 are cadmium iodide anti-types, and Fe,C3 89 is an isotype ofMh7C3. (Fe,.,Mn,.,)C has been the subject of a good three-dimensionalsingle-crystd analysis. A pleated layer hexagonal arrangement of metalatoms similar to that in &-iron and the &-carbide was found.A new silicon carbide 91 polytype 24R has been found to have the packingsequence ABCACBACBCABACBACABCBACB. In Zhdanov’s nomen-clature it is a I ‘ 5 sequence.” The ternary silicides, ThM2Si, g2 (M = Cr,Mn, Fe, Co, Ni, and Cu), have structures resembling the binary aluminidese.g., BaAl,, of the alkaline earth metals.Several metal phosphides have been examined. TiP0.63 93 is an isotypeof Mn,Si,. In Mo4P3 94 a complex packing of triangular prism of rnolyb-denum atoms encloses phosphorus atoms.There are no phosphorus-phosphorus distances less than 3.1; d(Mo-P) = 2*35-%69 A. Each molyb-denum has eight or nine other metal atoms a t 2.84-3.28 8. Mo3P 95 is ofthe general a-V,S type, d(Mo-P) = 2.48, d(Mo-Mo), = 3.01 8, but thereis one short Mo-Mo contact of 2-56 8. AgP, and CUP,^^ have similarstructures, The phosphorus is in corrugated layers formed from ten-mem-bered phosphorus rings sharing edges, d(P-P), = 2.20 A. The layers areheld together by copper-phosphorus bonds, d(Cu-P) = 2-37 A. The copperatoms occupy pairs of octahedral holes, d(Cu-Cu) == 2.48 A.Lammers and J. Zemann, 2. anorg. Chem., 1965, 334, 225.84 P. Larmners, Natumks., 1964, 51, 652.85 A.Ferrari, A. Braibanti, and A. Tiripicchio, Acta Cryst., 1965, 19, 629.86 G. S . Smith, G. Johnson, and P. C. Nordine, Acta Cryst., 1965, 19, 668.81 R. Juza and V. Wehle, Natumuias., 1965, 52, 537.88 A. L. Bowman, T. C. Wallace, J. L. Yarnell, R. G. Wenzel, and E. K. Storms,89 R. Fruchart, J.-P. Senateur, J.-P. Bouchaud, and A. Michel, Compt. rend., 1965,9 o E . J. Fasiska and G. A. Jeffrey, Acta Cryst., 1965, 19, 463.91 A. H. Games de Mesquita, Acta Cryst., 1965, 18, 128.* a Z . Ban and M. Sirkirica, Acta Cryst., 1965, 18, 694.93 R. Barnighausen, M. Knausenberger, and G. Brauer, Acta Cryst., 1965, 19, 1.9 4 S. Rundquist, Actu Chem. Scand., 1965, 19, 393.96B. Sellberg and S. Rundqvist, A& Chem. Stand., 1965, 19, 760.96 0. Olofsson, Acta Chem.Scand., 1965, 19, 229.Acta Cryst., 1965, 19, 6.280, 913H . M . POWELL, C . K . PROUT, S . C . WALLWORK 555Rare-earth sulphides, selenides, and tellurides, L,X, and L3X4,97 andthe mixed alkaline earth lathanide sulphides and selenides, ML2X4, havebeen investigated. The structures are very complex but there is a generalrelationship to the Th,P4 phase. The selenides, L2Se3, where L = Yb, Tm,Ho, and Y, and the tellurides, L,Te,, where L = Tm, Ho, Dy, and Y, havethe Sc2C3 structure which appears to be stable over a very narrow cation-anion ratio centred about 0.414.98The alkali metal thioferrates, RbFeS, and C S F ~ S , , ~ ~ have tetrahedrallyco-ordinated iron atoms and eight-co-ordinate casium and rubidium in asulphur matrix. A sodium chloride type AB structure found in GeSe loo isdistorted such that the longest Ge-Ge distances are approximately equal tothe shortest Ge-Se distances. Zirconium selenide,lOl ZrSe,, an isotype ofNbSe,, HfSe,, and TaSe,, has ZrSe distances of 2.73-2.75 ,& but no shortmetal-to-metal contacts. A short vanadium-to-vanadium contact of 2.83 8is found in patronite,l*2 V(S,),. Nb,Se, and Nb,Te, lo3 are isostructuraland related to Nb,Se,.Niobium-niobium contacts of 2.80 were found.NbSe,l04 has a three-layer form related to MoS,, two two-layer forms asfound in NbS,, and two new four-layer forms with stacking sequencesAABBAACC. and AABABBAB..., respectively. The trigonal prism islonger in the base and of less height than for MoS,. A structure related toCd( OH) ,, with stacking sequences ABCABC and the close packing distorted,was observed for ReSe,.l05 The metal atoms are clustered, &Re-Re) = 2-83,2-64, and 2.92 A.NiTe, PdTe, PtS,, PtSe , and PtTe, lo6 all have Cd(OH),structures. The x parameters have been investigated and range between0.227 and 0.254.The hydrated salt-like sulphides and selenides of sodium have beeninvestigated in detail. Na2S,9H,O and Na,Se,SH,O lo7 are isostructural.Each sodium ion is surrounded by an octahedron of water molecules. TheseNa(H,O), octahedra are of two types, one type sharing corners to give[Na(H20),]o, chains and the other sharing edges t o give [Na(H,O),],chains. The chains are joined together by O-H-O and 0-H.43 or O-H.-Sehydrogen bonds.In the sulphide d(Na-0) = 2.40, d(0-H-0) = 2-81, andd(0-H-S) = 3-24, and in the selenide d(Na-0) = 2.48, d(O-H.-*O) = 2.75,and d(O-H-.Se) = 3.31 8. The hydrated chalcogenides Na,S,SH,O,Na,Se,5Hz0, and Na2Te,5H,0 lo8 are also isostructural. One sodium atomis octahedrally co-ordinated to six water molecules, d(Na-0) = 2.38-2.41 A, and a second is at the centre of a square of water molecules with asulphur (or selenium or tellurium) atom at the apex completing a squareActa Cryst., 1965, 19, 14.97 J. Flahaut, M. Guittard, M. Patrie, M. P. Pardo, S. M. Golabi, and L. Domange,st? J. P. Dismukes and J. G. White, Inorg. Chem., 1965, 4, 970.nn W. Bronger, NatumuiSs., 1965, 52, 158.loo S. N. Dutta and G. A. Jeffrey, Inorg. Chem., 1965, 4, 1363.lol W.Kronert and W. Plieth, 2. anorg. Chem., 1965, 336, 207.lo* W. Klemn and H. G. Schnering, Natzcrwiss., 1965, 52, 12.loS K. Selte and A. Kjekshus, Acta Cryst., 1964, 17, 1568.lo4 B. E. Brown and D. J. Beerntsen, Acta Cryst., 1965, 18, 31.los N. W. Alcock and A. Kjekshus, Acta Chena. Scand., 1965, 19, 79.lo6 S. Furuseth, K. Selte, and A. Kjekshus, Acta Chem. Scand., 1965, 19, 257.D. Bedlivy and A. Preisinger, 2. K&t., 1965, 121, 114.lo* D. Bedliw and A. Preisinger, 2. Krist., 1965, 121, 131556 CRYSTALLOGRAPHYpyramid, d(Na-S) = 2.87, d(Na-Se) = 3-01 and d(Na-Te) = 3.23 8. TheNa(H,O), groups form chains which are connected into layers by the squarepyramidal groups. The layers are joined by O-H.-S (O-H...Se or O-H...Te)hydrogen bonds, d(O-H.-S) = 3.301, d(OH-43e) = 3-37 and 3-41, andd(O-H--Te) = 3-57-3.61 8.Halides.Hexagonal sodium neodymium fluoride, NaNdFp,lOg has thesame structure as the mineral gagarinite. The fluoride ion packing providesnine-co-ordinated sites for the neodymium, irregular octahedral sites for thesodium, and some vacant octahedral sites. Isolated ZnF4- tetrahedralgroups are found in the scheelites SrZnF4,llo d(Zn-F) = 1.80 8, and CaZnF,,d(Zn-F) = 1.93 A. The fluorothallates NaTlF, and LiT1F4111 have CaF,-type superlattices. The sodium and thallium ions are randomly distributed inthe former but the lithium and thallium are ordered. K,SnF,,KHF, 112 andNa,TiF,,NaHF, have structures containing MF6,- anions, HF,- anions,and alkali metal cations. No further details are given.The Zr,F135- anion(1) is found in Na,Zr,F13;114 &(Zr-F) = 2-10 for bridging F and 2.07, 2.10,and 2.00 for non-bridging F. Catena-di-p-fluoro-diaquohafnium(1v)monohydrate, HfF43H,0,ll5 is not an isotype of ZrF4,3H,0. The hafniumcompound contains hafnium ions at the centre of a slightly distorted squareantiprism formed by two water molecules, four fluoride ions, bridging to twoother hafnium ions, and two non-bridging fluoride ions. The bridgingfluoride ions join the co-ordination polyhedra together to form chains.The co-ordination polyhedron of ZrF4,3H,0 is very similar but containsthree water molecules, and two polyhedra only are joined to form dimers.Essentially trigonal dodecahedra1 ZrFs4- groups, but with some con-siderable deviation from the theoretical shape, occur in Li,BeF4,ZrFs,116d(Zr-F) = 2-05 and 2-16 8.The BeF,, groups are regular tetrahedra,d(Be-F) = 1-57 A.Gallium trichloride,ll7 GaCl,, is in the form of dimers arranged so that thechlorine atoms form close packed sheets with one-quarter of the sites vacantand the gallium atoms occupy one-half of the intervening tetrahedral sites.Movement of the Ga3+ and C1- ions to vacancies is considered a possibleexplanation of the enhanced electrical conductivity of this salt. Thechlorides of iridium(n1) and ruthenium(rr1) are isotypes of A!1c13,d(1r-Cl) = 2.30-2.39 8. The ferroelectric low-temperature form ofCsGeC1311g is a deformed perowskite. In each GeCl, group three Ge-C1distances are 2.31 8 and three 2.87 8.In the high-temperature form all sixare 2.74 A. Slightly distorted isolated FeC1,- tetrahedra, d(Fe-C1) = 2-1s-2-22 8, L(C1-Fe-Cl) = 104-9-1 12.7 *, are found in NaFeC14.120 A potassium100 J. H. Burns, Ilzorg. Chem., 1965, 4, 881.1 1 O H. G. Schnering and P. Bleckmann, Naturzuiss., 1965, 52, 538.111R. Hoppe and C. Hebecker, 2. anorg. Chem., 1965, 335, 85.112 R. Weiss, B. Chewier, and J. Fischer, Compt. rend., 1965, 260, 3664.118 R. Weiss, J. Fischer, and B. Chewier, Cumpt. rend., 1965, 260, 3401.114 R. M. Herak, S. S. Malcic, and L. M. Manojlovic, Acta Cryst., 1965, 18, 520.116 D. Hall, C. E. F. Rickard, and T. N. Waters, Nature, 1965, 20'9, 405.116 D. R. Sears and J. H. Burns, J . Chent. Phys., 1964, 41, 3478.117 S. C. Wallwork and I.J. Worrall, J . Chena. SOC., 1965, 1816.118 K. Brodersen, F. Moers, and H. G. Schnering, Naturwiss., 1965, 52, 205.lZo R. R. Richards and N. W. Gregory, J . Phys. Chein., 1965, 89, 239.-4. N. Christensen and S. E. Rasmussen, Acta Chem. Scand., 1965, 19, 421H . 51. POWELL, C . K . PROUT, S. C . WALLWORK 557chloroplatinate type structure is slightly distorted in K2TeBr,,121 to givebetter packing, d(Te-Br) = 2-71 8.A number of additional examples of metal atom clusters in transitionmetal halides have been observed. The Ta6I1Z+ group is found in TaJ,, 122an isotype of Nb6Cl14, d(Ta-Ta) = 2.79-3.07 A, and d(Ta-I) = 2.70-2.83 8. K2Re,C1,,2H20 123 contains the Re,Cl, group ( 2 ) . The rheniuF - / F \ FFF- / ! \ F' 1 '\ li F-' F ' I/ <,F- FIatoms are drawn towards the centre of the group out of the chlorine planessuch that the metal-to-metal distance is only %24A but the chlorine-to-chlorine contact distance is 3-32 8.Twocrystalline forms of the pyridinium salt (pyH)HRe*IBr, contain the dimericanion [Br4RsReBr4]4- or [HBr4R~ReBr4H]2-.124 Th eeight bromine atomsform a tetragonal prism within which are two rhenium atoms on thetetragonal axis. In the tetragonal crystalline form the prism has height3.516 8 and the Re-Re distance is 2.207 8, so the metal atoms are dis-placed noticeably out of the square end-planes toward the centreof the prism, d(R>e-Br) = 2-48 A. The dimensions of the complexion are not greatly different in the orthorhombic form. The Tc,CI,group in (NH4),Tc2C1,,2H20 125 is isostructural with the Re,Cl, group,d(Tc-C1) = 2-34-2-36, d(Tc-Tc) = 2.13 8.The metal-to-metal bond issaid to be quadruple formed from one a-bond, two sz-bonds and a &bond. Incontrast, the TcCl, 126 structure is made of TcCI, octahedra linked by edgesinto endless chains. The distance Tc-C1 is 2.36 8 but the shortest metal-to-metal contact is 3-59 8. The Re,BrIl2- ion in Cs,Re,Br,, 12' has the sameconfiguration as the Re,ClIl2- ion, d(Re-Re) = 2.48 A. The quinoliniumsalt (qnH)2Re4Br,, 12, contains ReBr, octahedral groups and Re,Br,groups, d(Re-Re) = 2.465. The black-red crystals of platinum(I1) chlorideare composed of discrete Pt6Cl1, groups.129 The platinum atoms are at thecorners of an octahedron, edge length = 3-32-3040 A, and bridging chlorineatoms along each of the twelve edges of the octahedron have d(Pt-C1) = 2-34-2.39 A.The distance Re41 is 2-29 8.lZ1 I.D. Brown, Caizad. J . Chena., 1964, 42, 2758.lZ2 D. Bauer, H. G. Schnering, and H. Schafer, J. Less-Common Metak, 1965, 8,388.lZ3 F. A. Cotton and C. B. Harris, Inorg. Chenz., 1965, 4, 330.lZ4 P. A. Koz'min, V. G. Kuznetsov, and Z. V. Popova, Zhur. Stmkt. Khim., 1965,lZb F. A. Cotton and W. K. Bratton, J . Anaer. Chew Soc., 1965, 87, 921.lzsM. Elder and B. R. Penfold, Chem. Conzm., 1965, 308.12' M. Elder and B. R. Penfold, Nature, 1965, 205, 276.lZ8 F. A. Cotton and S. J. Lippard, Iaorg. Chem., 1965, 4, 59.lz9 K. Rrodermn, G. Thiele, and H. G. Schnering, 2. atzorg. Chem., 1965, 337, 120.6, 651858 CRY STALL0 GRAPHYStereochemistry of Compounds of Some Elements of Groups III, IV, V,a d VI.--W.N. Lipscomb and his co-workers have continued their studiesof the boranes and derivatives. A single-crystal X-ray diffraction study ofp-diborane 130 has produced boron-hydrogen distances, 1.10 for terminalhydrogen atoms and 1-23 and 1-25 8 for bridging hydrogen atoms, that arenotably shorter than the corresponding values (1.196 and 1.339) obtainedfrom vapour-phase electron-diffraction work. An icosahedral cap is formedin B,H,C2H2 and B4H,C2(CH3),131 from a B3C2 five-membered ring withadjacent carbon atoms and two BHB bridges, and an apex boron atom (3),d(C-C) = 1.42, d(GCH,) = 1.51 A. There are strong resemblances toB,HlO in geometry and valence structure.A complete Bloc2 icosahedronwith adjacent carbon atoms occurs in BloHlo(CCH2Br)2.132 The carbon-to-carbon bond length, 1.64 A, is not abnormally short and disproves the sugges-tion that the B, ,C2 unit should be regarded as an ethylene decarborane system.A similar but distorted icosahedral unit, also with bonded adjacent carbonatoms a t 1-67 8 separation, occurs in the 12-dicarbaclovododecaboranederivative B,oC18H2C,H,.133 The chlorine atoms substitute on all boronatoms except. the two most positive, that is, the two bound directly to thecarbon atoms. The long carbon-to-carbon bond distances are predicted bythe authors from the distribution of thirteen electron pairs along the thirtyicosahedral edges. Lipscomb 134 has worked out a general geometricaltheory of the boron hydrides, and has shown that only a limited numberof new compounds of this type can now be expected.Tetramethyl-ammonium hexahydrohexaborate I35 has a fluorite-type structure formedfrom B,H62- octahedra and tetramethylammonium ions. Thioboric acid 136is said t o be isostructural with (BSBr),. Examination of the borazoleB3(C2H5)3N3(C2H5)3 137 has confirmed the presence of the expected planarhexagonal B3N, ring, C~(B-N)~~ = 1423 8. The ethyl groups point alter-nately above and below the ring. Two new types of electron-deficient boronhydride derivative have been found. The &st, a polyborane hydridoman-ganese carbonyl, HMn,(CO)lo(BH,), (4),138 has both metal-hydrogen-metalH- H(3)/\H-H-130 H.W. Smith and W. N. Lipscomb, J . Chem. Phys., 1965, 43, 1060.131 F. P. Boer, W. E. Streib, and W. N. Lipscomb, Inorg. Chem., 1964, 3, 1666.132 D. Voet and W. N. Lipscomb, Inorg. O h . , 1964, 3, 1679.133 J. A. Potenza and W. N. Lipscomb, I w g . C h . , 1964, 3, 1673.134 W. N. Lipscomb, Inorg. Chem., 1964, 3, 1683.lS5R. Schaeffer, Q. Johnson, and G. S. Smith, Inorg. Chem., 1965, 4, 917.136 D. Thomas and C. Tridot, Compt. rend., 1964, 259, 3559.13' M. A. Viswamitra and S. N. Vaidya, 2. Krist., 1965, 121, 472.138 H. D. Kaesz, W. Fellmann, G. R. Wilkes, and L. F. Dahl, J . Amer. Chem. SOC.,1965, 87, 2753H . M . POWELL, C . K . PROUT, S . C . WALLWORK 559bridges, d(Mh--fi) = 2.845 A, and metal-hydrogen-boron bridges,d(Mn-B) = 2.30 8, d(B-B) = 1.76 8.These three-centre bridges enablethe electron configuration to obey the inert-gas rule. The manganese-to-manganese hydrogen bridge has a metal- to-metal contact notably shorterthan that of 2.923 A found for the metal-to-metal bond in Mn,(CO),,. Inthe second compound, C5H5FeBgC,Hll (5),139 the C 2 B g set of atoms formeleven corners of an icosahedral group with the iron atom a t the twelfthcorner such that iron has two carbon neighbours, d(Fe-4) = 2.04, and threeboron neighbours, d(Fe-B) = 2.09 8. The cyclopentadienyl group is onthe other side of the iron atom.Aluminium hydride-iVNiV‘N’-tetramethylethylenediamine crystals con-tain endless chains of AlH, units and diamine units.140 The aluminiumatom has trigonal bipyramidal co-ordination with equatorial hydrogenatoms, d(A1-H) = 1.50-1.60, and the bidentate bridging amine,(5)(Reproduced, by permission, from A.Zalkin, D. H. Templeton, andT. E. Hopkins, J . AWT. Chem. Soc., 1965, 87, 3989.)d(A1-N) = 2-19 and 2.24 8, is in the trans configuration. In the 1 : 1 adductof aluminium borohydride and trimethylamine (6),141 both the alu-minium and nitrogen have a. tetrahedral co-ordination, d(C-N) = 1.58,d(A1-B) = 2-19, and d(A1-N) = 2.01 8.The tricyanomethide ion, C(CN),-, has attracted some attention. Inthe copper(n) tricyanomethide, CU[C(CN),],,~~~ it is reported as planar. Thecopper atoms are octahedrally co-ordinated to six cyano groups, four inone plane with d(Cu-N) = 1.98 8, and two apical, with d(Cu-N) = 2.49 A.These cyano groups belong to six different tricyanomethide ions.In theammonium salt,143 a more favourable case for accurate structure analysis,the [C(CN),]- ion departs slightly from planarity, and the charge is said t obe on the central carbon atom, d(G-C) = 1.40, d(C-N) = 1.15 8, withe.s.d.’s of 0.01 8. The cyanamide ion is linear in strontium cyanamide,14413sA. Zalkin, D. H. Templeton, and T. E. Hopkins, J . Amer. Ohem. Soc., 1965,87, 3988.14* G. J. Palenik, Acta Cry&, 1964, 17, 1573.141 N. A. Bailey, P. H. Bird, and M. G. H. Wallbridge, Chem. Comm., 1965, 438.142 C. Biondi, M. Bonamico, L. Torelli, and A. Vaciago, Chem. Comm., 1965, 191.143 R. Desiderato and R. L. Sass, Acta Cryst., 1965, 18, 1.144 K.-G. Strid and N.-G. Vannerberg, Naturwhs., 1965, 52, 258560 CRYSTALLOGRAPHYd(C-N) = 1.22 A.Thiocarbonic acid 143 contains a planar CS, group withL(S-C-S) = 120" and d(C-S) = 1.68-1-78 8. Distorted SiN,O tetra-hedra are linked together in a three-dimensional network in Si2N 20,1*6d(Si-0) = 1.62 and d(Si-N) = 1.72 8.A comparison of the molecular structures of ammonia and [2H3]-ammonia147 has been made from electron diffraction data; d(N-H) =1-019and d(N-D) = 1.020 A are not significantly different. The e.s.d.'sfor the angles are each 1.0" and it is highly probable that the difference,L(H-N-H) = 109.1", L(D-N-D) = 106-1 O is real. In crystals of hydrazinemonohydrate148 each water molecule is linked by six hydrogen bonds(2.79, 2.79, 3.11, 3.11, 3-15, and 3.15 8) to hydrazine molecules, but thehydrazine molecules are not bound to each other.The authors discuss thehydrogen atom arrangement.The 1935 analysis of the crystal structure of black phosphorus149 hasbeen confirmed and a refinement carried out. The phosphorus atom islinked in a pyramid to three others at distances 2.224 (two) and 2-244 A.The pyramidal angles at the apex are 96.54" (two) and 102.1". Non-planarphosphorus rings are found in (PC6H,), 150 and (PC,H,),.15f In (PC,H,),the five-membered ring is an equilateral pentagon of symmetry m withd(P-P), = 2.217, d(P-C) = 1.843 8, and L(P-P-P),, = 100.01". Thesix-membered phosphorus ring in (PC,H5)e is in the chair form, the phenylgroups are substituted in the equatorial positions, and the planes of phenylgroups are perpendicular to the ring system.Phosphorus oxides 152 ofcomposition between P,O, and P,O, are a series of mixed crystals of thetwo molecules P40, and P409. These molecules are formed from a trigonalpyramid of phosphorus atoms linked by six oxygen atoms along the pyramidedges. The remaining two (or three) oxygen atoms are terminal with respectto phosphorus, d(P-0) (bridging) = 1.59-1.66, d(P-0) (terminal) = 1.44 A.The phosphorus bonds in methyl ethylene phosphate (7) 15, are distortedso that L(O-P-0) in the ring is only 99". The oxygens bound t o carbonare 1.57 A from the phosphorus, and the fourth oxygen atom is at 1.44 Afrom the phosphorus. A two-dimensional analysis of diphenylphosphinicacid,154 (C,H,),PO(OH), shows that the molecdes link to form endlesshelices by hydrogen-bonding, d(O-H...O) = 2.74 8.The distances d(P-0)and d(P-C) are given as 1-49 and 1.81 8. A trigonal bipyramidal PO,group has been observed in a pentaoxyphosphorane.155 The two crystallo-graphically distinct anions in Ca(C,oH7HP04)2,3H20, calcium l-naphthylphosphate trihydrate,15, each have four P-0 bonds. Each calcium ion has146 B. Krebs and G. Gattow, Natuwk., 1964, 51, 544.14* I. Idrestedt and C. Brosset, Acta Chem. Scad., 1964, 18, 1879.147 0. Bastiansen and B. Beagley, Acta Chem. Scud., 1964, 18, 2077.148R. Liminga and I. Olovsson, Acta Cryst., 1964, 17, 1523.160 J. J. Daly, J . Chem. SOC., 1964, 6147.161 J. J. Daly, J . Chem. SOC., 1965, 4789.lL2 K.-H. Jost, Acta Cryst., 1964, 17, 1593.163 T.A. Steitz and W. N. Lipscomb, J . Amer. Chem. SOC., 1965, 87, 2488.164 Lyan Dun-Chai and T'Yan Go-Dzen, Acta C h h . Sinica, 1965, 31, 155.1 6 5 W. C. Hamilton, S. J. LaPlaca, and F. Ramirez, J . Arner. Chem. SOC., 1965,156 Chi-Tang Li and C. x'. Caughlan, Acta Crpt., 1965, 19, 637.A. Brown and S. Rundquist, Acta Cryst., 1965, 19, 684.87, 127H . M . POWELL, C . K. PROUT, S. C . WALLWORK 5619 PHseven oxygen neighbours, four PO, groups and three from water molecules.More (PN), ring systems have been investigated. A three-dimensionaldifference synthesis calculated in the late stages of the refinement of thestructure of sodium trimetaphosphimate tetrahydrate,Na,(NHP0,),,4H20,157 clearly shows maxima corresponding to hydrogenatoms linked to the nitrogen atoms in the ring anion (8) found in the crystal,d(P-N) = 1-68, d(P-0) = 1.49 A, L(P-N-P) = 123", andL(N-P-N) = 104.5".Hydrogen atoms were not observed on differencesyntheses of the tetrametaphosphinic acid dihydrate, (NH)4P,0,H4,2H20,at any stage. However, a comparison of bond lengths and angles with thosefound in Na(NHP0,),,4H20 suggests that it contains the similar anion (9).The crystals are formed from sheets in which the acid is probably in theform (H,O),+[ (NH),P,O,H J2-. Neighbouring anions are linked by shorthydrogen bonds, d(O.-H.-O) = 2-46 A. The sheets are connected byN-H-0 hydrogen bonds, d(N-H*-.O) = 2-79 and 2.81, d(P-N) = 1-66,d(P-0) = 1.52 and 1-48 A. In 2,4,6-trimethoxy-l,3,5-trimethyl-2,4,6-oxocyclotriphosphazane,~~~ N,Me,P,O,( OMe),, the ring has the form of atwisted boat.The angles within the ring at the phosphorus are 108, 109,and 106", and at the nitrogen 120, 120, and 123", d(P-N) = 1.66-1.72,d(P-0) = 1.42-1-46, d(P-OMe) = 1-63-1.64, and d(N-Me) = 1.46-1.51 A. The P-N distances in the previous three ring systems are inter-mediate between the single bond distance and those found in the cyclophos-phazenes such as N,(PCl,),P(C,H,), ( 10).159 The ring in this compoundI \ (9) 0 0c', ,N,CI--Y p c i'P'N N/ \Ph Phdeparts slightly from planarity in a chair form, with d(P-N) = 1.555 (two),1.578 (two), and 1.615 13, (two). The longest of these distances are thoseinvolving the phosphorus atom bound to phenyl groups. A new ring P2S,has been found in diphosphorus hexathiodibromide, P,S,Br, (1 l).lS0 Thering has a skew boat configuration with d(P-S) = 2.10 and d(S-S) = 2.03 8.lS7 R.Olthof, T. Migchelsen, and A. Vos, Acta Cryst., 1965, 19, 596.16* G. B. Ansell and G. J. Bullen, Chem. Comm., 1965, 493.lS9N. V. Mani, F. R. Ahmed, and W. H. Bonnes, Acta Cryst., 1965, 19, 693.160 F. W. B. Einstein, B. R. Penfold, and Q. T. Tapsell, Inorg. Ghem., 1965, 4,186562 CRYSTALLOGRAPHYThe terminal atoms are disordered. The sulphur-deficient phase, P4S6. 5,161has the same molecular dimension as the P4S7 phase except that the uniqueP-P bond has the more usual length of 2-26 8. A crystallographic Z-axispasses through the molecule. There is direct crystallographic evidence forthe sulphur deficiency at the terminal positions.Cacodylic acid (12) 162 occurs in the crystal as centrosymmetric hydrogenbonded dimers d(0-H-0) = 2.57 8.The tetrahedral angles are 106-115",and the arsenic-oxygen and arsenic-carbon bonds are not unusual,d(C-As) = 1-91 d(As-0) = 1.62 8. The bulk structure of hutchinson-site,l63 (Tl,Pb),As,S,, consists of two types of slab running parallel to(010). In one kind of slab As& chains running along c are joined laterallyby ASS, pyramids to give a complex layer. In the other kind, isolatedAs,S, groups together with thallium and lead atoms form layer with someresemblance to a, distorted PbS structure. Laulite, CUASS,~~ is a sphderitederivative structure in which all atoms have tetrahedral environments,copper as CuS3As groups, arsenic as AsAs,CuS, and sulphur as SCu,As.Thearsenic atoms form extended planar zig-zag chains through the structure.Arsenic tri-iodide 16, has an approximately hexagonal close packed arrayof iodine atoms with arsenic displaced from the centres of octahedralholes, so the structure may also be considered as built up from AsI, mole-cules, d(As-I) = 2-56, d(As-I) = 3.50 8. The structure does not resembleA neutron-Wraction study of hydrogen peroxidel66 has confirmed theX-ray structure. The oxygen-hydrogen distance is 0.988 & 0.005 beforeand 1.008 0405 A after correction for thermal motion, d(0-0) = 1.453Jr 0.007 and d(O-H-.O) = 2.799 -J= 0.008 A.Monoclinic sulphur cryshls 1 6 7 are formed from a disordered arrayof eight-membered crown rings, &(S-S) = 2-06 8.The structure ofthe ring compound S7NH 168 has been refined, &(S-S) = 2-05, 2.07, 2.02,d(N-S) = 1-73 8. The cyclic planar cation S4Ns+ (13) is found in thiotri-thiazyl nitrate,l69 S,N&O,. The sulphur-to-sulphur bond is single,d(S-S) = 2.06, &(S-N) = 1.52-1.56 A, L(N-S-N) = 155.4, 149-1, and135", L(N-S-N) = 116.7 and 119.2," L(S-S-N) = 113.1 and 110.9". TheNO,- ion makes no abnormally short contacts with the S4N3- ion. TheD. T. Dixon, F. W. B. Einstein, and B. R. Penfold, Acta Cryst., 1965, 18, 221.lea J. Trotter and T. Zobel, J . Chem. SOC., 1965, 4466.163 Y. Takeuchi, S. Ghose, and W. Nowacki, 2. K ~ b t . , 1965, 121, 321.D. C. Craig and N. C. Stephenson, Acta Cryst., 1965, 19, 543.166 J.Potter, 2. Krist., 1965, 121, 81.lB6 W. R. Busing and H. A. Levy, J . Chern. Phys., 1966, 42, 3054.lS7D. E. Sands, J . Amer. Chem. Soc., 1966, 87, 1395.lB8 J. Wehs and H.-8. Neubert, A& Cr2/8t., 1965, 18, 815.16* J. Weiss, 2. a m g . Chem., 1904, 833, 314; A. W. Cordes, F. R. Kruh, and E. I(.BiI3.Gordon, Inwg. Chern., 1965, 4, 681H. &I. POWELL, C. K . PROUT, S . C . WALLWORK 563structure has been confirmed by an independent determination. TheSeCN- ion in KSeCN has been shown t o be linear,l7* d ( S 4 ) = 1-83,Organoxnetallic Compounds.-The so-called '' alkali carbonyl " sodiumacetylenediolate, NaOCECONa, has a crystal structure made up of rod-likeNaOC=CONa groups,171 d(C=C) = 1.19, d(C=O) = 1-37, d(Na-0) = 2-20 and2-47 A, packed in chains, d(Na-Na) = 3.57 A.Sodium meth~xide,~'~NaOCH,, is isostructural with LiOCH,. Each sodium is surrounded by atetrahedron of oxygen atoms at 2.32 A, and each oxygen by a tetrahedronof sodium atoms, d(C-0) = 1.41 A. The etherate of sodium hydridodi-ethylber~llate,l7~ [NaO( C2H 5 ) ,],(C2H5) J3e2H,, has ( C2H &,Be,H, units,d(Be-C) = 1.80, d(Be-H) = 1.4 8, associated with pairs of sodium etheratemolecules to form chains. The shortest sodium-hydrogen distance is 2.4 8,the same as that found in sodium hydride. Diethylmagnesium, Mg(C2H5)2,174forms endless chains (14), d(Mg-Mg) = 2.67, similar to those found inMg(CH,),, where d(Mg-Mg) = 2.72 A. The magnesium-to-carbon bondlength is 2.26 A. In the solid state the Grignard reagent ethylmagnesiumbromide dietherate is a monomer.175 The magnesium atom is surrounded bya bromine atom a t 2.48 A, a carbon of the ethyl group a t 2.16 A, and twooxygens of different ether molecules a t 2.03 and 2.06 8.It differs from thephenylmagnesium bromide dietherate 176 in that the magnesium is only0.2 A above the carbon-oxygen plane of the tetrahedron. The phenyld(C-N) = 1.12 A.ff ,CH3H3C -Sn i 'CH3OH1 I ,CH3HJC - S,n ,1 CH3OHIII~ -~170 D. D. Swank and R. D. Willett, Imwg. Oh., 1965, 4, 499.17aE. We&, 2. anorg. Oh., 1964, 832, 197.17* G. W. Adamson and H. M. M. Sheazer, Cbm. Cmm., 1965, 240.I 7 4 E. Webs, J. OrganmtaUdo Chm,, 1965, 4, 101.E. Weiss and W. Buchner, Chm. Ber., 1966, 98, 126.L. J. Guggenberger and R.E. Rundle, J. Amer. Chm. Soo., 1964, S& 6344.G. Stucky and R. E. Rundle, J . AM. Chern. Soc., 1964, 86, 4826564 CRYSTALLOGRAPHYderivative yields the less accurate results. In neither compound is there anyevidence for intermolecular interactions. The compound of formulaMg,Br,0,4C,H1,,0 177 is formed in small amounts when oxygen contaminatesa, Grignard reagent. The oxygen atom is surrounded by four magnesiumatoms a t 1.95 A at the corners of a tetrahedron. The six bromine atoms arealong the edges of this tetrahedron, d(Mg-Br) = 2.61, and the ether mole-cules are attached to each magnesium at 2.1 1 A. Each magnesium atom hasan irregular five-co-ordination. A two-dimensional analysis of trimethyltinhydroxide gives the structure ( 15).178/=\ CH CH(CO),Fe -(16b)(Reproduced, by permission, from P.Piret, J. Meunier-Piret,and M. Van Meerssche, Acta Cryst., 1965, 19, 82.)There are two isomers of Fe2(CO),(C,H,), produced in reactions betweeniron carbonyls and acetylenes. The first of these, an orange-red form, hasthe structure (16a and 16b).179 The metal-to-metal bond length is 2.527177 G. Stucky and R. E. Rundle, J. Amer. Chem. SOC., 1964, 88, 4821.1 7 8 N, Kasai, K. Yasuda, and R. Okawara, J. Organonzetallic Chem., 1965, 3, 172.1 7 9 P. Piret, J. Meunier-Piret, and M. Van Meerssche, Acta Cryst., 1965, 19, 78, 85H . M. POWELL, C . K . PROUT, S . C . WALLWORB 565and the bonds from metal to carbonyl carbon atoms have lengths in therange 1.610-1*838 8; d(Fe-CH,) = 1.96 and 2.02; d(Fe-CH) = 2.10, 2-262.07, and 2.26 A.The structure provides an inert gas E.A.N. for iron. Inthe second, dark red, isomer the acetylene molecules combine to form amethene cyclopentadienyl system rather than the 3-methylene 14-penta:diene of the first isomer. The compound (17) is the remarkable product.In it, d(Fe-Fe) = 2.679, d(Fe-CO) = 1.761-1.809, d(Fe-CH) = 2-123 8.The reaction of Fe,(CO) with diphenylacetylene produces a less stableviolet and a more stable black isomer Fe,(CO)a(C,H5C,C,H5)2.180 Theseisomers form a new type of three-centre complex. In the violet isomer thediphenylacetylene molecules remain separate (1 8), and in the black isomerthey unite to form a ferracyclopentadiene (19). Three-centre arrangementof metal atoms differs in the two isomers.In the black form there are twometal-to-metal bonds, d(Fe-Fe) = 2.428, 2-435, and in the violet form there(Reproduced, by permission, from P. Piret, J. Meunier-Piret,and M. Van Meerssche, Acta Cryst., 1965, 19, 88.)are three, d(Fe-Fe) = 2.469, 2.457, and 2.592 A. Platinum in dipentene-platinum( 11) chloride has square-planar co-ordination to the two cis chlorineatoms and two ethylenic groups (20).lS1 One of these ethylenic groups isperpendicular to the platinum chlorine plane but the second makes an angleof 62" to the plane, d(Pt-Cl) = 2-32-2.34, d(Pt-11) = 2-14-2.13 A, Crys-tals of catena-p- chloro- (cyclo- octatetraene) copper(1) 82 contain continuouschains of (Cu-CI) with one olefinic bond completing a distorted trigonalplanar co-ordination sphere and approximately coplanar with the copperCCIEo R'. P.Dodge and V. Schomaker, J . OrganometaZlic Chem., 1965, 3, 274.N. C. Baenziger, R. C. Medrud, and J. R. Doyle, Acta Cryst., 1965, 18, 237.182 N. C. Baenziger, H. L. Haight, and J. R. Doyle, Inorg. Chenz., 1964, 3, 1529(Reproduced, by permission, from R. P. Dodge and V. Schomaker,J . Orgaiiometallic Chem., 1965, 3, 279 and 280.H. M . PO\\-ELL, C . K . PEOUT, S . C . WALLWORK 567cchlorine system (21), d(Cu-j!) = 2.07, d(Cu-CI) = 2.29 A. A detailed re-Cfinenlent of the norbornadienepalladium chloride has failed to confirm thelong C=C system.183 The C=C distance is now given as 1-366 8, and theformer value is said to be in error.When diphenylacetylene reacts with palladium dichloride and butadiene-palIadium dichloride, two different compounds having empirical formulaC,,Hz50PdC1 are formed.l84 In each of these isomers the dimeric unit[ (CSH5)4C40C2H5]zPdC12 has a symmetrical planar Pd2C1, fragment bondedto the allylic part of a non-planar cyclobutenyl ring.The two forms aregeometrical isomers, one endo- (22) and one exo-form (23). They are relatedby interchange of phenyl and ethoxy groups attached to the saturatedcarbon atom of the cyclobutene ring. An X-ray structure analysis has shownthat the product of the reaction of eyclopentadienylsodium with methyl-cyclobutadienenickel &chloride is also a cyclobutene compound ( 24).la5Two compounds have been found to have ally1 groups directly bound toCH2\/CE-IZC\/ CH= Y CH CH,I I t CH CHC!-I 7 CH\lE3 N.C. Baenziger, G. F. Richards, and J. R. Doyle, Acta Cryst., 1965, 18, 924.L. F. Dahl and W. E. Oberhansli, IT'rZorg. Chem., 1965, 4, 629.W. Oberhansli and L. F. Dahl, Inorg. Chem,., 1965, 4, 150568 CRYSTALLOGRAPHY(23)(Reproduced, by permission, from L. F. Dahl and W. E. Oberhansl,Inorg. Chem., 1965, 4, 634 and 635.)palladium. Allylpalladium chloride, (C,H,PdCl)2,186 has been the subjectof an excellent analysis at -140". The crystals are composed of discretemolecules (25). The planes of allyl groups in the dimer are inclined at 111.5"to the Pdz2Cl, plane. The central allyl carbon atom is 0.53 A above this plane,and the peripheral atoms 0.101 and 0.053 A below it.These peripheralcarbon atoms subtend an angle of 119" at the central carbon atom. ThelS6 A. E. Smith, Acta Cryst., 1965, 18, 331H . M. POWELL, C . E. PROOT, S. C . WALLWORK 569C*-C--C n- bond system is delocalised. The second allyl compound studiedis allylpalladium acetate (26).187 The allyl groups make dihedral angles of125" and 110" with the 0-Pd-0 planes. The palladium atoms are 2-94 Afrom each other, d(C-C)(allyl == 1.34, 1.37, 1.42, and 1-33 8.An accurate x-ray analysis of Fe(CO),(C,H,C,C,H,), has shown it tocontain a square-planar cyclobutadiene ring, d(C-C) = 1.46, d(Fe-C) = 2.054-2.091 8. The phenyl groups are bent 10" out of the plane of the C, ring.The metal co-ordination sphere is completed by the three carbonyl groups,d(FeC0) = 1.742-1.762 A, which are on the opposite side of the iron atomto the C, ring.188 Dibutadienerhodium(1) chloride is said to have thestructure (27),1*9 d(Rh-C1) = 2.45, d(Rh-C) = 2-20 8.Tricarbonylbicyclo-[3,2,l]octadienyliron (28) I90 tetrafluoroborate is claimed to be unique inthat the five carbon atoms of the co-ordinating unit, d(Fe-C,,,,,,,,,) = 2.24,2.26, 2.21, 2.17, and 2.09 8, are not consecutive in a chain. The co-ordina-tion of the iron atom is described as octahedral. Troponeiron tricarbonyl191is a complex (29) in which the iron atom is bound to three carbonyl groups,d(Fe-CO) = 1.75-1.77, and four carbon atoms of the seven-membered6 40I/ ~ O, c =\ /,cF e,/ ;I\,0ring, d(Fe-C)( bonding) = 2.04-2.15, d(Fe-C)(non-bonding) = 2-99-3.44 .&Examination of the structure of 1.1 -tetramethyethyleneferrocene (30)shows that the rings are almost e~lipsed.1~~ The molecule is obviouslystrained; the dihedral angle between the rings is 23", and the exocycliocarbon-to-carbon bonds are bent 11 O from the ring planes.In contrast, therings are staggered in a-keto-1,l'-trimethyleneferrocene (31).lg3 The struc-ture is less strained and the dihedral angle only 8".The molecule of formula, CO,C,,IE,, 194 has two similar sandwich frag-ments joined through a bridging five-membered ring. The sandwich frag-ment differs from the ferrocene type. The outer ring, not joined to the bridge,is flat; the inner ring is not; four of its atoms are coplanar and the fifth is0.46 5 0.04 A out of the plane away from the cobalt.This carbon atomforms an ordinary bond to the bridging ring. Each cobalt atom has Co-Cla' M. R. Churchill and R. Mason, Nature, 1964, 204, 777.la9 L. Porri, A. Lionatti, G. Allegra, and A. Immirzi, Chem. Conzm., 1965, 336.lDo T. N. Margulis, L. Schiff, and M. Rosenblum, J. Amer. Chem. SOC., 1965, 87,lQ1 R. P. Dodge, J . Amer. Chern. Soc., 1964, 836, 5429.lQoM. Burke Laing and K. N. Trueblood, Acta Cryst., 1965, 19, 373.lg3 N. D. Jones, R. E. Marsh, and J. H. Richards, Acta Cryst., 1965, 19, 330.lD4 0. V. Starovskii and Yu. T. Struchkov, Zhur. strukt. Khim., 1965, 6, 248.R. P. Dodge and V. Schomaker, Acta Cryst., 1966, 18, 614.3269.570 CRY STALL0 GXAPHYFe I I coCIdistances, 2.06 (five, in the outer ring), 2.58 (one, the carbon which links tothe bridge), 2-03 (two, to carbons next to the bridge-linked carbon, 1.94 A(two, to carbons furthest from the bridge-linked carbon).Terferrocenyl,l95Fe,C,,H,,, is centrosymmetric. The central Fe sandwich has an antipris-rnatic form, and the two to either side of it have prismatic forms. In thecrystal of diethylbiferro~enyl,~~~ the molecule occupies a symmetry centre,i.e., the configuration is trans relative to the C,-CI' bond joining the ferro-cenyls. This bond has length 1.38 8. The sandwich is practically prismaticwith a relative rotation of the ring of only 4", in contrast to the antiprismaticforms found in ferrocene and derivatives, and different from that in biferro-cenyl (relative rotation 16").A centrosymmetric molecule is found forbis( chloroferrocenyl) .197 The ferrocene groups are nearly prismatic (5 O out)and there is a small angle between the mean planes of the two halves of eachsandwich. The chlorine atom is in position 2, i.e., ortho to the line joiningthe two ferrocenyls. The C-C distance (1.46 A) is significantly greater thanthat in ferrocene and biferrocenyl; d(Fe-C) = 2.07 A. The structure ofthe n-cyclopentadienyl( 1 -benzoylcyclopentadiene)cobalt (32), has been ex-amined, and the bonding in this type of compound has been discussed in somedetail.19* Tris-mcyclopentadienyluranium chloride ls9 is claimed to havethe form (33). The co-ordination about the uranium is that of a distortedtetrahedron. The lengths of the uranium-carbon (2.74 b) and the uranium-chlorine (2.56 8) bonds suggests that they are ionic.The electron densityin the region of the cyclopentsdiene molecules is very diffuse. The structureanalysis 200 of [(C5H5)@02H(PMe2)(CO),] gives evidence for a symmetricalbent three-centre metal-hydrogen-metal bond. Two indistinguishableC,H,Mo(CO) fragments are linked to the two molybdenum atoms by asymmetrical bridging P(CH,) group. The symmetrical localised metalenvironments are said to imply equal association of both molybdenum atomswith the hydrogen. The probable location of the hydrogen atom is a t aregular co-ordination site 1.8 A from each metal atom; this is deduced fromthe close resemblance to the geometry of the [C,H,Mo(CO),], molecule.195 Z. L.Kaluski and Yu. T. Struchkov, Z h w . s h k t . Khim., 1965, 6, 316.lS8 Z. L. Kaluski and Yu. T. Struchkov, Zhur. stmlct. Khim., 1968, 6, 104.197 Z, L. Kaluski and Yu. T. Struchkov, Zhur. strukt. Khim., 1965, 6, 745.19* M. R. Churchill, J . Organom&allic Chem., 1965, 4, 258.l S O Chi-Hsia Wong, Tung-Mou Yen, and Tseng-Yuh Lee, Acta Cryst., 1965, 18,200 R. J. Doedens and L. F. Dahl, J. Amp. Chem. SOC., 1965, 87, 2576.340H. M. POWELL, C. K. PROUT, S . C. WALLWORK 57 1The bent three-centre Mo-H-Mo system with two electrons from the metalatoms and one from the hydrogen accounts for the diamagnetism withoutinvolving a Mo-Mo bond.Further support for the delocalisation in dibenzenechromium is derivedfrom a demonstration 201 that there is no significant distortion from the freebenzene structure in benzenechromium tricarbonyl and that the distortedbenzene structure in hexmethylbenzenechromium tricarbonyl ,02 has a2, not a 3, symmetry axis.The lengths of the carbon-to-carbon bondsaround the ring are, in sequence, 1.37, 1-45, 1.46, 1.38, 1.42, and 1.43 A. Athreefold orientational disorder in crystals of thiophenchromium tricar-bony1 203 precluded accurate structure determination.TTAs-copper-manganese pentacarbonyl (TTAs is a tritertiary arsine),triphenylgermanium-manganese pentacarbonyl, and triphenylphosphine-gold-cobalt tetracarbonyl give bond distances between dissimilar metalatoms of 2.56 & 0.01 (Cu-Mn), 2.54 and 2.53 -& 0.02 (Ge-Mh), and2.50 & 0.02 8 (AU-CO).'~~A surprisingly short Rh-C bond (2.06 8) is observed between the rhodiumatom and a pentafluoroethyl group in iodocarbonyl-n-cyclopentadienyl-pentafluoroethylrhodium, n-C,H,Rh(CO)C,F,I. The rhodium is describedas octahedrally co-ordinated and the cyclopentadenyl group terdentate.The distance rhodium to the carbonyl carbon atom is 1-96 A but d(Rh-I) isnot given.The possible double-bond character of the Rh-C2F5 system isdisc~ssed.~O~ The hydrogen atom was not found in a determination of thestructure of manganese pentacarbonyl hydride, Mn(C0) 5H,2°6 but it isinferred that it occupies the sixth octahedral position, d(M.n-CO), = 1.836 A,L(GMn-C) = 92-96.1". The Bh(CO), equatorial group is not planar.The shortest &-Mn contact is 5-167 8. Ditechnetium decacarbonyl,Tc2(CO),,, is isostructural 207 with Mn,(CO),,, d(Tc-Tc) = 3.04, d(Tc-C),= 1.83 8.The equatorial Tc-C bonds are 0.1 A longer than the apicalbonds. The deca( methyl-isocyano)dicobalt(n) ' 0 8 ion is an isostere of&manganese decacarbonyl. The total symmetry is D4d, and the (MeNC),Cosquare pyramids are staggered. The metal-to-metal bond has length 2.74 8.The tricyclic[SFe(C0)J2 has the form (34).209 The iron stereochemistry is that of adistorted tetragonal pyramid, d(Fe-CO) = 1-75-1.80, d(Fe-S) = 2.22-2.24,d(S-S) = 2-01, and d(Fe-Fe) = 2-55 8. The iron-iron bond is described asbent, in that the only possible pair of overlapping iron orbitals meet a t anangle of 130". This molecule occurs also in crystals resulting from theinteraction of HFe(CO), with sulphite ion.210 These crystals contain a1 : 1 mixture of S,Fe,(CO), and S,Fe,(CO), molecules.The crystal andSome iron carbonyl sulphides are of special interest.201 M. F. Bailey and L. F. Dahl, Inorg. Chem., 1965, 4, 1314.eo2M. F. Bailey and L. F. Dahl, Inorg. Chem., 1965, 4, 1298.aoaM. F. Bailey and L. F. Dahl, Inorg. Chem., 1965, 4, 1306.206M. R. Churchill, Chem. Comm., 1965, 86.20* S. J. La Plactt, W. C. Hamilton, and J. A. Ibers, Inmg. Chern., 1964, 3, 1491.207 M. F. Bailey and L. F. Dahl, Inmg. Chern., 1965, 4, 1140.208F. A. Cotton, T. G. Dunne, and J. S. Wood, Inorg. Chem., 1964, 3, 1495.Chin Hsuan Wei and L. F. Dahl, Inorg. Chem., 1965, 4, 1.310 C. Wei and L. F. Dahl, Inorg. Chem., 1965, 4, 493.B.T. Kilbourn, T. L. Blundell, and H. M. Powell, Chem. Comm., 1965, 444572 CRYSTALLOGRAPHYmolecular structure of cis-(diethy1enetriamine)molybdenum tricarbonyl211has been determined, d(Mo-N) = 2.311, 2.310, and 2.348, d(Mo-C) = 1.933,1.953, and 1.942 8. The dependence of 310-C bond length on bond order isdiscussed.9 Oc d '\ /In ,u -ethylenediaminebis( trimethylacetylacetonato)platinum( IV) (35) ,212the ethylenediamine is at a centre of symmetry. The amine nitrogen atomsare bound to two different platinum atoms, d(PtN) = 2.31 8. Eachplatinum atom is octahedrally co-ordinated to three cis-methyl groups,d(Pt-Me) = 2-03-2.17, one chelating acetylacetone residue, d(Pt-0) = 2.10and 2.18 8, and the amine nitrogen. A number of related compounds havebeen reported in previous years.Co-ordination Compounds.-More structures than ever before have beenreported in this field. The work has been in general of excellent quality.Again the main emphasis has been on metals of the first transition seriesbut there has been a small but significant increase in interest outside thisseries.In sodium complexes NaC1,5l/,NK3 and NaBr,51/,NH3 213 halide ionsand ammonia molecules are cubic close packed in such a way that thesodium ions can occupy octahedrally co-ordinated sites with only ammoniamolecules as near neighbours.The Na(NH3), octahedra share corners andthe octahedra are distorted so that the co-ordination is effectively five-foldwith one ammonia molecule a t a greater distance. The ethylenediaminete-fra-acetic acid (AH,) complexes of lanthanum, La( OH 2),,AH,3H,0 (36) 214and KLa(OH2),,A,5H20 (37),215 have lanthanum ions ten- and nine-co-ordinate, respectively.Both co-ordination polyhedra are related to theeight-co-ordinated system of Mo(CN),~-. In the ten-co-ordinated complex thesix HA ligand atoms occupy five dodecahedral sites, a water moleculeoccupies a sixth, and the remaining three waker molecules share the remain-ing two dodecahedral sites, d(La-O)=* = 2.537, d(La-N) = 2.865, andd(La-OH,) = 2.609 A. The La3+ ion is off-centre above the plane of theHA4 oxygen atoms. The nine-co-ordinate complex is similarly based on the211 F. A. Cotton and R. M. Wing, Inorg. Chem., 1965, 4, 314.212 A. Robson and M. R. Truter, J . Chem. SOC., 1965, 630.213 I.Ulovsson, Acta Cry&, 1965, 18, 879.214 M. D. Lind, B. Lee, and J. L. Hoard, J . Amer. Chem. SOC., 1965, 87, 1611.215 J. L. Hoard, B. Lee, and M. D. Lind, J . Amer. Chem. SOC., 1965, 87, 1612H . 3f. POWELL, C . K . PROUT, S. C . WALLWORK 573(Reproduced, by permission, from J. L. Hoard, Byungkook Lee, andM. D. Lind, J . Arner. Chem. Soc., 1965, 87, 1611 and 1613.)dodecahedron with two water molecules.at one vertex. The La3+ ion isoff-centre 0.6 A out of the plane of the HA oxygen atoms.The calcium ion in weddellite, CaC20,,(2 + x)H20, is eight-co-ordinatedat the centre of a distorted cubic anti-prism of oxygen atoms.216 Thebisnitrilotriacetatozirconate( rv) ion is also eight-co-ordinated but based ona dodecahedron, d(Zr-0) = 2.251, 2.156, and 2.130, d(Zr-N) = 2-439In vanadyl sulphate, VOS0,,218 VO, octahedra are linked together bysharing opposite corners.The oxygen atoms of the equatorial plane arefrom sulphate groups, d ( V - 0 ) = 2.00-2-06 8, and these sulphate groupscouple the chains to each other. The vanadyl oxygens joining the VO,216 C. Sterling, Ada Cryst., 1965, 18, 917.217 J. L. Hoard, E. Willstadter, and J. V. Silverton, J . Anwr. Chem. SOC., 1965,P. Kierkegaard, J. M. Longo, and B.-0. Marinder, Acta Chern. Scand., 1965,87, 1610.19, 763574 CRYSTALLOGRAPHYoctahedra within a chain form an unsymmetrical bridge, d(V-O)(bridging) =1.59 and 2-28 8. The co-ordination polyhedron of the vanadium atom inthe cis-form of bis-( l-phenylbutane-1,3-dionato)vanadyl 219 is a tetragonalpyramid with the vanadyl oxygen at the apex, d(V-0) = 1.612.The vana-dium atom is above the basal plane of four oxygen atoms, d(V-0) = 1.940-1-986 A.Trisacetylacetonatochromium(II1) 220 has the expected octahedral chelatestructure, d( Cr-0) = 1.942-1.959 A. Di-p-diphenylphosphinato-bisacetyl-acetonatodichromium( 111) (38) 221 is a centrosymmetric molecule with sym-metrical PO, bridges, d(Cr-0) = 1.97 and 1.95, d(P-0) = 1.49 and 162 8.The basic chromium acetate, Cr3( CH3COO),0C1,5H,0, has an oxygen atomHC -- CMe' \ MeC/\/ p \0 O \0 0''P'a t the centre of an equilateral triangle of chromium atoms (39). Pairs ofacetate ions bridge pairs of chromium atoms, and each chromium co-ordina-tion octahedron is completed by a water molecule.222 The iron(m) complexis isostructural.Three more chromium peroxo-complexes, potassiumdiperoxotricy anochromate,K,[Cr( 0,) 2( CN) 3],223 oxodiperoxo-1 ,lO-phenan-throlinechromium( m), and diperoxoaquoethylenediaminechromium( vr) hy-are reported to have trigonal bipyramidal co-ordination of chro-mium. In all cases the oxygen-to-oxygen bond of the peroxo group has alength between 1.42 and 1.455 8. The Cr-O,,, bond is reported to be oflength 1.58 8.A compound previously reported as a molybdenum(v) oxalate has beenshown to have one additional oxygen and is K,[MoO~(C~O,)H~O],O.~~~The centrosymmetric complex anion has two molybdenum atoms withoctahedral co-ordination and a linear Mo-O-No bridge. The Mo-0 bondsvary considerably in length, d(Mo=O) = 1.68 and 1.70, d(Mo-O)(bridging) =1.876, d(Mo-O)(oxalate) = 2.087 and 2.186, d(M-OH,) = 2.33 8.Theseand the angular variations correlate well with simple considerations of inter-atomic repulsion and Mo-0 bond orders. Molybdenum(n) acetate ,,, is anisotype of copper acetate. The distance Mo-Mo, 2.11, is 0.8 8 less than thesum of the single bond radii (cf. copper acetate and allylpallsldium acetate).In Cs2MnC1,,2H,0 and Rb2MnC1,,2H,0,227 each manganese is co-ordi-219 P.-K. Hon, R. L. Belford, and C. E. Pfluger, J. Chem. Phys., 1965, 43, 1323.aao B. Morosin, Acta Cryst., 1965, 19, 131.221 C. E. Wilkes and R. A. Jacobson, Inorg. Chem., 1965, 4, 99.2z8 R. Stomberg, Nature, 1965, 205, 71.224 R. Stomberg, Nature, 1965, 207, 76.zZ* D.Lawton and R. Mason, J. Amer. Chem. SOC., 1965, 87, 921.927 S. J. Jensen, Acta Chem. Scand., 1964, 18, 2085.B. N. Figgis and G. B. Robertson, Nature, 1965, 205, 694.F. A. Cotton, 8. M. Morehouse, and J. S. Wood, Inorg. Chem., 1964, 3, 1603H. M. POWELL, C. K . PROUT, S. C . WALLWORKcH3L CH,F e575s/ \0 0 (41)nated to two water molecules, d(Mn-0) = 2.13 8, and four chloride ions,d(&h-Cl) = 2.54 8. Iron(@ chloride dihydrate 228 has chains of FeC1,,2H20octahedra, sharing edges of their equatorial planes of four chloride ions,d(Fe-C1) = 2.49, d(Fe-0) = 2.07 8. The chains are linked by hydrogenbonds of the water molecules, Manganese@) chloride dihydrate has asimilar structure. The iron atoms in a-chlorohaxnh 229 and methoxyiron(m)mesoporphyrin-IX dimethyl ester 230 have tetragonal pyramidal co-ordi-nation with the iron atoms 0.475 and 0.49 8, respectively, above the basalplane of the pyramid.It is suggested that the substantial displacement ofthe iron atom above the nitrogen plane is a normal structural feature of aniron porphyrin. Iron cupferron, Fe(O,N,C,H,), (40),231 is an octahedralchelate complex. The distance Fe-O,2*00 8, is rather long, and it is said thatthese bonds are ionic. Dichlorotris( triphenylphosphine)ruthenium( n) 232 isa five-co-ordinated d6-complexwith a distorted tetragonal pyramidal co-ordin-ation. The basal plane contains two triphenylphosphine molecules (trans),d(Ru-P) = 2.230 and 2.374, and two chlorine atoms, d(Ru-61) = 2-387 and2.388 A.The apical phosphorus is a t 2.412 8. The atom nearest to thesite which would complete a distorted octahedron is a hydrogen of a phenylgroup 2.59 distant. Tristriphenylphosphinerhodium carbonyl hydride 233also has a five-co-ordinated metal atom, but in this case the configurationis trigonal bipyramidal. The phosphorus atoms are in the equatorial plane,d(Rh-P) = 2.315-2.336, and the hydrogen, and the carbonyl a t theapices, d(Rh-H) = 1.60 &- 0.12, d(Rh-C) = 1.829 A. The rhodium atomis displaced 0-36 A from the equatorial plane towards the carbonylcarbon atom. The ruthenium sulphur dioxide co-ordination compound,[RU~~(NH~),(SO~)C~]C~,~~~ contains the octahedral complex cation (41),d(Ru-N) = 2-13, d(Ru-S) = 2.072, and d(S-0) = 1.46 and 1.39 A.Aninteresting neutron-diffraction study 235 of disodium tetranitritonitroso-2zaB. Morosin and E. J. Graeber, J . Chem. Phys., 1965, 42, 898.22g D. F. Koenig, Acta Cryst., 1965, 18, 671.280 J. L. Hoard, M. J. Hamor, T. A. Hamor, and W. S. Caughey, 3. Arner. Chem.2s1 D. Van Der Helm, L. L. Merritt, jun., and R. Degeilh, Ada Cryst., 1965, 18,zsa S. J. La Placa and J. A. Ibers, Inorg. Chem., 1965, 4, 779.S. J. La Placa and J. A. Ibers, Acta Cryst., 1965, 18, 611.284 L. H. Vogt, jun., J. T. Kate, and S. E. Wiberley, Iwrg. Chem., 1965, 4, 1157.m6 S. H. Simonsen and M. H. Mueller, J . Inorg. Nuclear Chem., 1965, 27, 309.Soc., 1965, 87, 2312.355576 CRYSTALLOGRAPHYhydroxyruthenate(111) dihydrate shows that the crystals contain the octa-hedral anion Ru(NO,),(NO)OH.The nitrito groups form a square,d(Ru-N) = 2.08, d(N-0) = 1-21 8. The hydroxpyl, d(Ru-0) = 1.95, andthe nitrosyl group, d(Ru-NO) = 1.75 8, are in trans positions. TheRu-N-0 system is linear, d(N-0) = 1.13 8.The six-co-ordinated iridium in (NH4)5[Ir(S03)2C14] has the pyramidalsulphite groups in the trans positions. In (NH,)4[Ir(S03)2C13],4H,0 theiridium is also six-co-ordinated with one unidentate and one bidentate SO,in a monomer complex.236Two independent investigations 237 show that the black form of nitro-sylpenta-amminecobalt dichloride contains monomeric [Co(NH,),N0]2+cations. Four ammonia molecules form the equatorial plane of an octahe-dron, d(Co-N),, = 1.95, 1.93 8. The fZth ammonia a t an apex is at arather greater distance, cZ(Co-N)(apex) = 2.30, 2.28.For the nitroxylgroup at the other apex, d(Co-N) = 2-03, 1.99 A. In each case the values ofDale and Hodgkin are given first. These workers observed a much longerN-0 bond in the nitrosyl group, d(N-0) = 1-41 than did the other group,d(N-0) = 1.26 8. The crystals were found to be complex orthorhombictwins, and this may introduce some uncertainty concerning these unusualinteratomic distances. The cations in carbonatopenta-amminecobalt(m)bromide 238 and acetopenta-amminecobalt( 111) chloride perchlorate 239 thecarbonate and acetate ligands are unidentate. In the former the five am-monia nitrogen atoms are reported to be 1.93-1-94 A from the cobalt, andin the latter at an average distance of 2.00 8.The Co-0-C angle is 137"for the carbonato-complex. A second carbonato oxygen is hydrogen-bonded to an ammonia group in the same complex. In deca-ammina-p-peroxodicobalt tetrathiocyanate 240 the Co-N distance is 1-95-1.98 8.The [ (NH,),Co-02-Co-(NH,),14f cation differs from[(NH,),CO-O,-CO(NH,),]~+ in that the 0-0 bond is inclined a t an angle tothe Co-Co vector, ~(Co-O-O)=112". The distance Co-0, 1.83 8, is rathershort, and d ( 0 - 0 ) , 1.65 A, is abnormally long. The spin-free cobalt com-plex, Co( Ph2MeAsO),, has tetragonal pyramidal five-co-ordination of thecobalt(=) n t ~ m . ~ ~ ~ One of the perchlorate ions is a t the apex. In thebasal plane of the pyramid cobalt is joined to a second perchlorate ion andthe Ph,BleAsO molecules.Perchlorate ligands have also been observed inbis 2,5-dithiahexanecobaIt(11) per~hlorate.~~~ The sulphur-containing ligandsform the equatorial plane of an octahedron, d(Co-S) = 2.29, and the per-chlorate ions are a t the apices, d(Co-0) = 2-34 A. Shorter Co-S distances2.159 and 2.163 8, are observed in the square planar low-spin complexanion of di( tetra-n- buty1ammonium)cobalt (11) bis( maleonitriledithiolate) .243236 M. -4. Porai-Koshits, S. P. Ionov, and Z. M. Novozhenyuk, Zhur. strukt. Khim.,1965, 6, 173.237 D. Dale and D. C. Hodgkin, J . Chem. Soc., 1965, 1364; D. Hall and A. A. Taggart,ibid., p. 1359.238 H. C. Freeman and G. Robinson, J . Chern. SOC., 1965, 3194.239 E. B. Fleischer and R. Frost, J . Amer. Chem. SOC., 1965, 87, 3998.5 * * N.-G.Vannerberg, Acta Cryst., 1965, 18, 449.2 1 1 P. Pauling, G. B. Robertson, and G. A. Rodley, Nature, 1965, 207, 73.242 F, A. Cotton and D. L. Weaver, J. Amer. Chern. SOC., 1965, 87, 4189.243 J. D. Forrester, A. Zalkin, and D. H. Templeton, Inorg. Chem., 1964, 3, 1500H . M . POWELL, C . K . PROUT, S. C . WALLWORK 577In this crystal the shortest cobalt-cobalt distance is 9-81 8. Cobalt(1) hastrigonal bipyramidal co-ordination in pentakis(methylisonitrile)cobalt(I)perchlorate, with carbom atoms a t an average distance of 1.87 from thecobalt. This corresponds to a Co-C bond of order 1*5.244Isolated square planar Ni(CN)42- ions, d(Ni-C) = 1.84 and 1-92 8, arereported in the salt K,Ni(CN)4.245 The nickel cyanide system is not quitelinear, L(Ni-C-N) = 175".The quadridentate ligand in dichloro-1,4,8,11-tet'ra-azocyclotetradecanenickel( 11) 246 forms a square plane about the nickelatom, d(Ni-N) = 2-07 and 2.05 8. The chlorine atoms lie at octahedralsites 2.49 A from the nickel atom. The C-C and C-N bond distances in theligand are normal. There are no additional neighbours at short distances inthe square planar complex nickel(@ 2,4-diacetyldeuteroporphy~in-IXdimethyl e~ter,~47 d(Ni-N) = 1-95 and 1.96 A. The n-bond system of theporphyrin ligand appears to be delocalised. Tribenzo[b,f,j]l,6,9 Jtriaza-cycloduodecinenickel(I1) nitrate 248 the self condensation product of o-nmino-benzaldehyde in the presence of nickel ions contains six-co-ordinate octa-hedral nickel atoms with the terdentate ligand (42) occupying three cis sites.The ligand n-system appears not to be delocalised.The nitrate ion behavesas a bidentate ligand in dinitrito- (NNN' N'-tetramethylethy1enediamine)-nickel(11),~49 chelating through oxygen, d(Ni-0) = 2.06-2.12 A. Theauthors of this work suggest that in Hg(NO,),(NO,), the HgN, tetrahedronobserved in the Hg(NO,), group should not be regarded as significant andthat the nitrite ion here also chelates through oxygen. The supposedlinear nitrite ion reported as occurring in [ Ni(ethylenediamine),( NO 2)2]BF4has been shown 250 to be an error arising from misinterpretation of a disordereffect. Bis( acetylacetonato)nickel(II) 251 is trimeric, and bis(acety1acetonato)cobalt(I1) 252 tetrameric. In both compounds the metal atoms are octahe-drally co-ordinated and the acetylacetonate ligands behave similarly.In244 F. A. Cotton, T. G. Dunne, and J. S. Wood, Inorg. Chem., 1965, 4, 318.245 N.-0. Vannerberg, Acta Chem. Scand., 1964, 18, 2385.246 B. Bosnich, R. Mason, P. J. Pauling, G. B. Robertson, and M. L. Tobe, Chem.T. A. Hamor, W. S. Caughey, and J. L. Hoard, J . Amer. Chem. SOC., 1965,Comm., 1965, 97.87, 2305.248 E. B. Fleischer and E. Klem, Inorq. Chem., 1965, 4, 637.24s M. G. B. Drew and D. Rogers, Chem. Comm., 1965, 476.2 5 0 M. G. B. Drew, D. M. L. Goodgame, 39. A. Hitchman. and D. Rogers. Chenb..251 G. J. Rullen, R. Mason, and P. Pauling, Inorg. Chem., 1965, 4, 456.2 5 2 F. A. Cotton and R. C. Elder, Inorg. Chem., 1963, 4, 1145.Gonam..1965, 477578 C R Y S TALL0 GRAPH Ythe square planar complex, bis( trimethylenedinitroamine)nickelate(n) tetra-hydrate,25s only the amino nitrogen atoms co-ordinate with the nickel atom.Potassium nickel(1v) hexaoxidoiodate( VII),~~* KNiIO,, is isomorphous withPbSb,06. The oxygen atoms are hexagonally close packed. Every secondlayer of octahedral holes has nickel and iodine atom occupants leaving one-third empty and regularly distributed. In the intervening layers potassiumions occupy the octahedral holes between pairs of empty holes in the layersabove and below, d(K-0) = 2.57, d(Ni-0) = 2.00 and d(1-0) = 2-00 A.Two teams have each examined a group of complexes formed by a particu-lar ligand and three different metal atoms. The first group are the histidinecomplexes of nickel( n), cobalt(=), and cadmium( 11) .255 The nickel complex ofL-histidine and cobalt complex of DL-histidine have octahedral co-ordinationof the metal atom (43).Each histidine is terdentate through two nitrogenatoms and an oxygen atom. The cadmium compound with L-histidine isvery similar to the zinc complex. The metal-ligand distances (cadmiumD. M. Liebig and J. H. Robertson, J . Chem. Soc., 1965, 5801.K. A. Fraser, H. A. Long, R. Candlin, and M. M. Karding, Chem. Comm., 1965,254 N.-G. Vannerberg and I. Bloclrhammar, Acta Chem. Scand., 1965, 19, 875.344H . M . POWELL, C . K . PROUT, S . C . WALLWORK 579complex first and zinc complex second) are d(M-N) = 2-26,2.04, d(M-N,) =2.25, 2.05, d(M-0) = 2.49, 2.79 8.The second group are the diethyldi-thiocarbamates of nickel, copper, and ~inc.256 The nickel complex (44) issquare planar, d(Ni-S),, = 2-20 A, and the ligand is planar apart from theterminal methyl groups. Crystals of the copper and zinc complexes havevery nearly the same cell dimensions, and the same space-group but are notisostructural. In the copper eomplex a pair of centrosymmetrically relatedcopper atoms share a ligand sulphur atom to form a dimeric unit in whichthe copper atom has a distorted tetragonal bipyramidal co-ordination,d(Cu-S)(basal) = 2.297-2.339, (apical) = 2.861 A. The general form ofthe dimer recalls that of the copper dimethylglyoxime system. The zinccomplex also contains a dimeric unit but the zinc co-ordination is betterdescribed as distorted tetrahedral, d(Zn-S) = 2-331-2.443, with a fifth longcontact of 2.81 A.The long contact in the zinc complex is to a sulphuratom that is not shared by two zinc atoms. The bridging sulphur atom formstwo equivalent bonds.has a, squareplanar PtAs, unit, d(Pf-As) = 2.37 and 2.38 8, with two chlorine ionscushioned on four methyl groups. They are at 4-16 A from the platinumatom in directions approximately a t right angles to the square planar group.Potassium dioxalatoplatinate(I1) 258 contains isolated [Pt(C,O,) 2]2- ions,d( Pt-0) = 2.00 8. Hydridochlorobis( diphenylethy1phosphine)platinum isalso a square planar complex, d(Pt-P) = 2.27, d(Pt-C1) = 2.42 8 . 2 5 9 Thehydrogen atom was not located. The platinum-chlorine distance is con-sistent with the high lability of the hydrogen atom.There has been much activity concerning the crystal chemistry of coppercompounds.Crystals of CU(I)CN,NH, 260 are built up from polymericsheets [Cu(CN)Ja with ammonia bonded to the copper and protruding fromboth sides of the sheet. The orientation of the cyanide in the sheet is ambi-guous in respect of carbon and nitrogen sites. Short copper to coppercontacts of 2-42 A are found within the sheets. The copper(1) Sandmeyerreaction intermediate, C6H5N2Cu2Br3,261 has a structure of isolated benzene-diazonium ions and ( C U ~ B ~ ~ - - ) ~ , with anions of a crinkled ribbon form whichmay be simplified asDic hlor o - o - p hen y lene bis (dime t h y larsine) pla t inum (11) 25B r\ / cuI \\ / cu/ \B rB rBr Br\ / cu/ \B r Br\ / cu/ \Br Br856 M.Bonamico, G. Dessy, C. Mariani, A. Vaciago, and L. Zambonelli, Acta Cryst.,237 N. C. Stephenson, Acta Cryst., 1964, 17, 1517.25* R. Mattes and K. Krogmann, 2. anorg. Chem., 1964, 332, 247.2 5 * R. Eisenberg and J. A. Ibers, Inmg. Chem., 1965, 4, 773.260 D. T. Cromer, A. C. Larson, and R. €3. Roof, jun., Acta Cryst., 1965, 19, 192.261 C. Romming and K. Wmrstad, Chem. Cmm., 1965, 299.1965, 19, 619580 CRYSTALLOGRAPHYThe co-ordination around the copper atoms and central row of bromineatoms is tetrahedral, d(Cu-Br) = 2.45, on the edges of the ribbon, andd(Cu-Br) = 2.57 A for the central bromine atoms. There are no metal-to-metal bonds.Copper@) is found as the [CU(H,O),]~I- ion, distorted octahedral, incopper ammonium sulphate hexahydrate, d(Cu-0) = 2.19, 2.06, 2.04 A.262I n copper sulphate t r i h ~ d r a t e , ~ , ~ one oxygen of a sulphate group and threeof water molecules form a square planar CuO, group, d(Cu-O),, = 1-96 8.A distorted octahedron is completed by two sulphate ion oxygen atoms at2.39 and 2.45 8.The copper co-ordination polyhedra are joined by hydrogen-bonding. The anion in the fluoride N ~ , C U P , ~ , ~ is an endless chain ofCuF, edge-sharing octahedra, d(Cu-F) = 1.91, 1.90, and 2.36 8. There isan angular distortion of the octahedron similar to the distortion of the CrF,octahedra in chromous fluoride. In contrast, (N€€,),CuCl, z65 is describedas being formed from discrete planar CUCI,~- ions, d(Cu-C1) = 2-30, 2.33 A,wit,h longer copper-chlorine contacts of 2.79 A to neighbowing groups.Inthe anhydrous copper nitrate 266 a distorted CuO, octahedron is formed bycopper co-ordinating with six oxygen atoms of five nitrate ions; four dis-tances (Cu-0) lie between 1-92 and 2.02 and the two others are 2.43 and2.68 A. Each nitrate ion forms a bridge between two copper atoms, and inaddition one nitrate ion forms the weaker longer linkages. Copper and zincc r ~ c o n a t e e , ~ ~ ~ C,O,M(H,O),, are chain polymers. Each croconate grouphas three ligand oxygen atoms two of which chelate with one copper atomand the third is bound to a second copper so that the whole molecule is thebridging group. The three croconate oxygen atoms bound to any onecopper atom together with an oxygen of a water molecule form a squareplane, and a distorted octahedron is compieted by the remaining two watermolecules.The zinc compound is isostructural. The crystals of copperformate dihydrate 268 also contain polymers. These consist of three-dimen-sional chains of copper atoms joined by formate groups with an anti-symand anti-anti bridging arrangement. There are two crystallographicallydistinct copper atoms, both with distorted octahedral co-ordination,d{Cu(l)-0] = 2-02 (four) and 2.28 (two), d[Cu(2)-0] = 2.35 (two), 2-02(two) and 1.97 A (two). Discrete square planar groups are found in cop-per@) ethyl acetoacetate, d(Cu-0) = 1.91 and 1-94 A.269 Square planarcopper(=) also occurs in a bis-salicylaldehydatocopper(11) complex.270 Theligands are considerably distorted from planarity and weak polaris it t' ionbonding is postulated between the metal atom and the chelate ring.Twocopper atoms with different environments are found in acetylacetone-mono-(0-hydroxyanil) copper(I1) (45).271 The co-ordination of one copper atom in262M. W. Webb, H. F. Kay, and N. W. Grimes, Acta Cryst., 1965, 18, 740.263 R. Zahrobsky and W. H. Baur, Naturwiss., 1965, 52, 389.264 D. Babel, 2. anorg. Chern., 1965, 336, 200.265 R. D. Willett, J . Chem. Phys., 1964, 41, 2243.266 S. C. Wallwork and W. E. Addison, J . Chenz. SOC., 1965, 2925.267 M. D. Glick, G. L. Downs, and L. F. Dahl, Inorg. Chenz., 1964, 3, 1712.268 M. Bukowska-Strzyewska, Acta Cvyst., 1965, 19, 357.26s G.-4. Barclay and A. Cooper, J . Chem. SOC., 1965, 3746.z70D. Hall, A. J. McKinnon, and T. N. Waters, J . Chem. SOC., 1965, 425.2 7 1 G. A. Barclay and B. F. Hoskins, J . Chenz. SOC., 1965, 1979H . &I. POWELL, C . R. PROUT, S . C . WALLRORK 581(45) is square planar but that of the second is square pyramidal owing toco-ordination with an oxygen atom of a second dimeric molecule to forma tetramer ; d(Cu-0) (apical) = 2.64, d(Cu-O)(in plane) = 1-89 - 2.00,d(Cu-Cu) = 2.99 8. Square pyramidal copper(I1) is found in the pyridineadduct of bis- (N-phenylsalicylaldiminata)copper(11).~7~ The pyridine is a tthe apex, d(Cu-N) = 2.31 and the chelate molecules form the basal plane,d(Cu-N) = 2.01, 1.99, d(Cu-0) = 1.91 and 1.87 8.The apical Cu-N bondappears unusually short for such a bond. In the distorted octahedral coppersemicarbazide 273 complex, Cu[OC(NH,)NH*NH,],Cl,, the planar semi-carbazide molecules lie in the equatorial plane of the octahedron by co-ordi-nation through oxygen and hydrazine nitrogen atoms, d(Cu-X) = 1.99,d(Cu-0) = 1-97, and the octahedron is completed by two chloride ions,d(Cu-C1) = 2-84 A, The zinc compound is very similar, d(Zn-N) = 2.07,d(Zn-0) = 2-06, d(Zn-C1) = 2.59 8. The relatively longer apical bondlength in the copper compound arises from the Jahn-Teller effect in Cu2+.Freeman has continued his work on the metal peptide complexes. Indisodium glycylglycylglycylglycinocuprate( 11) 274 there are discrete metal0O- C - CHI-\ Me MeC - N 0 O=CNH- C-CH~- NH- C - c H ~ - N H ~ i\L/peptide anions.Each copper atom has square planar environment' of fournitrogen atoms of one peptide molecule, d(Cu-N) = 1.912, 1,923, 1.944, and3.028 8. There is an extremely involved hydrogen bonding system. Sodiumglycylglycylglycinocuprate( II) monohydrate (46) 275 is a dimer. Each copperatom is five-co-ordinated (square pyramidally). The basal plane of thepyramid is formed from three nitrogen atoms of one peptide molecule,d(Cu-N) = 2.039, 1497, and 1-891, and one oxygen terminal of the secondpeptide, d(Cu-0) = 1.933 A. The nitrogen nearest the terminal oxygenatoms of this second peptide molecule is the apical atom of the pyramid,d(Cu-N) = 2-568 8.The copper( nr) complex anion in tetra-n-butylammoniumcopper( ILT)bis( maleonitriledithiolate) 276 is square planar, d(Cu-S) = 2.158-2.177.Copper atonis are at 4.026 and 4.431 A from copper atoms in adjacentmolecules.In silver cyanate 277 each silver is linearly co-ordinated to nitrogen2 7 2 D.Hall, S. V. Sheat, and T. N. Waters, Chem. and Ind., 1965, 1428.273 M. Nardelli, G. F. Gasparri, P. Boldrini, and G. G. Battistini, Acta Cryst., 1965,2 7 4 H. C. Freeman and M. R. Taylor, Acta Cryst., 1965, 18, 939.275 H. C. Freeman, J. C. Schoone, and J. G. S h e , Acta Cry&., 1966, 18, 381.276 J. D. Forrester, A. Zalkin, and D. H. Templeton, Itaorg. Chem., 1964, 3, 1507.277 D. Britton and J. D. Dunitz, Acta Cryst., 1965, 18, 424.The shortest copper-copper contact is 3.077 A.19, 491582 ORYSTALLOGRAPHYatoms.In the endless -Ag-N-Ag-N-chains so formed, d(Ag-N) = 2.12, 8LAg-N-Ag = 97.7". Silver fulminate m8 on the other hand has an-Ag-C-Ag-C- system. There are two isomers; in the orthorhombic formthe silver carbon chains are infinite, d(Ag-C) = 2-23 8, L(C-Ag-C) = 180°,L(Ag-C-Ag) = 82", d(Ag.-Ag) = 2-93 A; in the rhombohedra1 form, thesilver-carbon chains are in the form of cyclic hexamers, d(Ag-C) = 2.16 A,,/(GAg-C) = 168", L(Ag-C-Ag) = 81", and d(Ag.-Ag) = 2.82 8. Halfthe silver atoms in AgCNAgNO, 279 form -Ag-C-N-Ag-C-N- linear chainswith no other neighbours closer than 3 8, and the remaining silver atomsand nitrate ions lie between these chains. Each of this second type of silveratom has seven nitrate oxygens and a cyanide group a t less than 3 8.There is no evidence for Ag,CN complex ions.Two kinds of distortedtetrahedral co-ordination of silver atoms are found in a helical chain polymerin monochloromonothiosemicarbazidesilver(r).280 The co-ordination poly-hedra AgC1,S2 and AgS3C1 are linked by sulphur and chlorine bridges,d(Ag-S) = 2.50, 2.48, 2.51, and 2.50, d(Ag-C1) = 2.66, 2-65, and 2-76 A.The fifth silver-sulphur contact, one of three made by that sulphur atom, isvery long d(Ag-S) = 2.7 8.The N-methylsalcylaldimine complexes of cobslt(n), manganese( n), andzinc@) are said to be isomorphous.2s1 The zinc complex (47) is an oxygen-bridged dimer containing zinc atoms in trigonal bipyramidal five- co- ordina-tion. The equatorial plane of the bipyramid has two nitrogen atoms and abridging oxygen atom, d(Zn-0) = 2.02, d(Zn-N) = 2.01 and 2-05 A.Thetwo apical oxygen atoms are bridging and are at distances 2.11 and 1.95 Afrom the zinc atom. The bonds are not significantly Werent in length fromthe equatorial bond. In (47) the dots represent the salicylaldimine residues.Bis(hydrazine)zinc isothiocyanate and bis( hydrazine)zinc acetate 2s2 arevery similar to the chlorides,2s3 d(Zn-N) for isothiocyanate is 2.17 and foracetate 2-18-2.21, d(Zn-0) = 2.15 A. A structure essentially similar tothat of basic beryllium acetate is claimed for Zn,[S,P( 0C3H,)],.284Cadmium tetrahedrally co-ordinated to sulphur has been found 285 incadmium n-butyl xanthate, d(Cd-S) = 2.62 and 2.56 8. Each sulphurbelongs to a different xanthic residue.278 D.Britton and J. D. Dunitz, Acta Cryst., 1965, 19, 662.%'9 D. Britton and J. D. Dunitz, Acta Cryst., 1965, 19, 815.280 M. Nardelli, G. F. Gasparri, G. G. Battisthi, and M. Musatti, Chem. Comm.,281 P. L. Orioli, M. Di Vaira, and L. Sacconi, Chem. Comm., 1965, 103.A. Ferrari, A. Braibanti, G. Bigliardi, and A. M. Lanferdi, Acta Cryst., 1965,283 Ann. Reports, 1963, 60, 693.284 A. J. Burn and G. W. Smith, Chem. Comm., 1965, 394.285 H. M. Rietveld and E. N. Maslen, Acta Cryst., 1965, 18, 429.1965, 187.18, 367H . &I. POWELL, C . K . PROUT, S . C . WALLWORK 5831,6-Dithiacyclodeca-cis-3,cis-8-diene forms an adduct with two moleculesof mercuric chloride to give a chain polymer (48).286 One mercury atom hasa tetrahedral environment of sulphur atoms, d(Hg-S) = 2.53 8.The othermercury forms part of an only slightly distorted HgCl, molecule. Dichloro-bisphenoxathiim-mercury is also a chain polymer (49).2a7 There have beentwo neutron-diffraction studies of uraiiyl complexes. Rubidium uranylnitrate 2s88 contains the anion (5.0). The uranyl oxygen is 1.75 A from the0N,c 9 I,A\'0 - u0 0\ 9.o' N - 00'N' (50)0O'N--0 7 OH,'OJ"/-O \H,O' 0 1'0-N,Ometal atom and the nitrate oxygen 2.48 8. The neutral molecule (51) foundin uranyl nitrate hexahydrate is very similar,2s9 d(U-0) = 1.77, 1-75, d(U-0)(nitrate) = 2.50,2-55, d(U-OH,) = 2.40 8. An X-ray structure analysis 290agrees with these results. Hexa-aquomagnesium hexanitratothorate dihy-drate crystals contain Mg(OH,), octahedral groups, d(15g-0) = 2.12 A,and Th(NO,), groups, in which the thorium is co-ordinated to twelve oxygenatoms at the corners of an irregular isosahedron, d(Th-O),, = 2-63 8.Single water molecules join the co-ordination polyhedra together by weakhydrogen b0nds.~~13. ORGANIC STRUCTURESCmboxylic Acids.-The asymmetry of the a carbon atom in a-monodeuterio-glycollate arises from the difference of the two isotopes H and D.Theabsolute configuration has been determined by the use of the anomalousscattering of lithium for neutrons and by the different neutron-scatteringamplitudes of H and D.292 This confirms that sterically-equivalent hydrogen286 K. K. Cheung and G. A. Sim, J. Chem. SOC., 1965, 5988.287 K. K.Cheung, R. S. McEwen, and G. A. Sim, Nature, 1965, 205, 383.289 J. C. Taylor and M. H. Mueller, Acta Cyst., 1965, 19, 536.290 D. Hall, A. D. Rae, and T. N, Waters, Acta Cryst., 1965, 19, 389.2 9 1 S. Scavnicar and B. Prodic, Acta Cryst., 1965, 18, 698.2 9 2 C. K. Johnson, E. J. Gab, M. R. Taylor, and I. A. Rose, J . Amer. Chmn. SOC.,G. A. Barclay, T. M. Sabine, and J. C. Taylor, Acta Cryst., 1965, 19, 205.1965, 87, 1802584 CRYSTALLOGRAPRYatoms of L-lactate and glycollate are removed by the muscle enzyme lacticdehydrogenase. An X-ray study 293 of lithium glycollate monohydrateshows the lithium and glycollate ions to be lying in a mirror plane with thewater molecules symmetrically disposed on either side of the plane. Thesebind the structural sheets together by hydrogen-bonding to the carboxyloxygen atoms in one layer, while completing the lithium co-ordination in thelayer above.Each lithium ion is surrounded in the mirror plane by OH andtwo 0- of separate C0,- groups and also by water molecules above andbelow the plane, completing a distorted trigonal bipyramid. Rubidiumhydrogen bisglycollate is a member of the series of strongly hydrogen-bonded acid salts. The glycollate anion and the glycollic acid molecule aredistinguishable 294 as separate species joined by a short (2.53 A), though notsymmetrical, hydrogen bond. This is in accordance with the infraredspectrum. The bisglycollate units are further linked by weaker hydrogenbonds into a three-dimensional array. K, Rb, and Cs hydrogen bistrifluoro-acetates have been studied 295 as further members of this acid salt series.The Rb and K salts are isomorphous, with two equivalent trifluoroacetateresidues joined by a short (2.435 8) hydrogen bond across a centre of inver-sion. This is one of the shortest accurately measured hydrogen bondsbetween carboxylic oxygen atoms.The Cs salt has a different structurewith a quasi-symmetrical hydrogen bond of length 2-38 &- 0.03 8.The crystal structure of potassium oxalate monohydrate has beenredetermined in X-ray 296 and neutron-diffraction ,97 studies, The centralC-C bond length is thus independently estimated as 1.585 & 0.015 and1.555 3: 0.012 8, but the agreement in the reported hydrogen-bond lengths(2.746 and 2.744 8) is good.The co-ordination of the water molecule isunusual in that two hydrogen atoms and two potassium ions lie almost in aplane around it. The oxalate ions are planar and are linked through thewater molecules by hydrogen bonds. Ammonium oxalate monohydrate has,similarly, been subjected to both an X-ray 298 and a neutron-diffraction 299study but, this time, the two estimates of d(C-C), 1-569 and 1.58 A, arevirtually in agreement. Both determinations find the oxalate ion to benon-planar; one half is twisted through 27" relative to the other, causing theion to become enantiomorphic.sOO This twisting is attributed to the hydrogenbonding in which the water molecules and ammonium ions form parallelhydrogen bonds linking the oxalate ions into chains, and the ammoniumions form further hydrogen bonds cross-linking the chains.Tetragonalcalcium 301 and strontium 302 oxalates are isomorphous and both containpart of their water of crystallisation in a zeolitic form. Within experimentalerror, the oxalate ions in these structures have mmm symmetry. A long293 R. H. Colton and D. E. Henn, Acta Cryst., 1965, 18, 820.Z94L. Golic and J. C. Speakman, J . Chern. SOC., 1965, 2521.2s6 L. Golic and J. C. Speakman, J . Chem. SOC., 1965, 2530.206 B. F. Pedersen, Acta Chem. Scad., 1964, 18, 1635.29' R. Chidamberam, A. Sequeira, and S. K. Sikka, J . Chem. Phys., 1964, 41, 3616.298 J. H. Robertson, Acta Cryst., 1965, 18, 410.290 V. M. Padmansbhan, S. Srikantha, and S. M. Ali, Acta C q s t . , 1965, 18, 567.300 J.H. Robertson, Acta Cryst., 1965, 18, 417.301 C. Sterling, Acta Cryst., 1966, 18, 917.302 C. Sterling, Nature, 1965, 205, 558H . M . POWELL, C . K . PROUT, S . C . WALLWORK 585C-C bond (1.55 A) is again found in the more accurately determined calciumsalt, and this long central bond seems to be a common feature of oxalate ionstructures, whether they are twisted or planar. I n a-hydroxycarboxylicacids there is a tendency for the -C(OH)CO,H group to be planar. The struc-ture of tartronic acid (a-hydroxymalonic acid) has been determined 303 to seewhether this tendency is able to compet'e with the steric hindrance which, inmalonic acid, causes one carboxyl group to be approximately perpendicularto the other. It is found that the carboxyl groups are rotated 15" and 18-5",respectively, from the position of coplanarity with the central C-0 bond,each in the same sense, so that the compromise is reached not far fromcoplanarity.The usual dimerisation of carboxyl groups through hydrogenbonds takes place at each end of the molecule, thereby forming infinitechains. It is questionable whether the central OH group is involved inbydrogen-bonding a t all, though there is a contact of 3.02 8 with the C=Ogroup of an adjacent molecule. An attempt to distinguish between trulyand statistically centred short hydrogen bonds has been made,304 in theneutron-diffrac tion study of potassium hydrogen chloromaleate, by ensuringthat the two hydrogen- bonded oxygen atoms are chemically non-equivalent.The nearly planar anion has a ring structure with an intramolecular O-.-H.*.Ohydrogen bond of length 2.40 8.The hydrogen atom is equidistant fromthe two oxygen atoms within experimental error, and the amplitude ofvibration predicted spectroscopically is not much less than the observedblurring of the hydrogen position. It is possible to reject the view that theremight be two hydrogen positions with an energy barrier between themhigher than the zero-point energy. The hydrogen maleate ion, thoughstrained, remains planar by forming the intramolecular hydrogen bond. Bycontrast, the ethylenetetracarboxylate ion ( -0,C)(H0,C)C=C(C0,H)(C02--)relieves its strain by twisting of the carboxylic groups about the C-C b~nds.~O~It therefore forms inter- rather than intra-molecular hydrogen bonds,In the isomorphous structures of rubidium and potassium mesotartratedihydrate, the mesotartrate ion is found 306 to have an asymmetric conforma-tion, so the optical inactivity is not due to internal molecular compensationbut to the presence cf both enantiomorphs in the structure.The twoC(C0,-) groups are in planes a t about 57" to each other, giving an ethaneconformation about the central C-C bond. It is likely that enantiomorphicconformations of the molecule occur even in solution, because they are foundin all modifications of the solid free acid. A study 307 of the isomorphouslithium and sodium dihydrogen citrates shows that it is the central carboxylgroup that has ionised, since it has two equivalent CO distances (1.253 and1.252 A).The C-C bond length, 1.566 8, of this central carboxyl groupresembles the corresponding distances in oxalate ions. The central OHgroup forms an intramolecular hydrogen bond to one carboxylic OH, andd(OH***O) = 2.51 & 0.01 A.303 B. P. van Eijck, J. A. Kanters, and J. Kroon, Acta Cryst., 1965, 19, 435.304 R. D. Ellison and H. A. Levy, Acta Cryst., 1965, 19, 260.305 S. K. Kumra and S. F. Darlow, Acta Cryd., 1965, 18, 98.306 J. Kroon, A. F. Peedeman, and J. M. Bijvoet, Acta Cryst., 1965, 19, 293.307 J. P. Glusker, D. van der Helm, W. E. Love, M. L. Dornberg, J. A. Minkin,C. K. Johnson, and A. L. Patterson, Actu Cryst., 1965, 19, 561586 CRY STALL0 CfRAPHYboth carboxylic OH groups form intermolecular hydrogen bonds to 0- onadjacent citrate ions.Each citrate ion forms two bidentate chelate rings bymaking four polar links to a pair of centrosymmetrically related metal ions.In magnesium citrate decahydrate, each citrate chelates in a terdentate polarmanner to one magnesium ion using the central OH and carboxylate groupand one of the terminal carboxylate oxygen atoms.308 The backbone carbonatoms are nearly coplanar, and the central carboxylate group and itsa-hydroxyl oxygen atom form another plane at 86.4" to the backbone plane.One-third of the magnesium ions are octahedrally co-ordinated with watermolecules, and the whole structure is best represented by the formula[Mg(H20) 61"gC6H 20) 1 2 ~ ~ ~ 2 0 .The crystal structures of adipic 309 and suberic 31* acids(HO,CfCH,];CO,H; n = 4 and 6, respectively) have been redetermined inorder to locate the hydrogen atoms.The molecules are linked in the usualway, at each end, with pairs of hydrogen-bonds between carboxyl groups ofcentrosymmetrically related molecules. In both structures the carboxylgroups linked in this way are approximately coplanar but the hydrogen atomsforming the hydrogen bonds are situated about 0-15 L% out of the plane.The OH.-O angle is 162" in adipic acid and 166" in suberic acid, and thehydrogen-bond lengths are 2.64 and 2.65 L%, respectively. The OH distancesof 1-15 and 1-19 8, respectively, are both a little long. The hydrocarbonchains in form B of potassium palmitate, (CH3*[CH2],,C0,-K+) are allparallel and packed according to a somewhat distorted version of the usualtriclinic ~ub-cell.~ll The angle of tilt of the chain axes is 52".The carboxylgroup is rotated about 16" round the first C-C bond, and, since similarrotations are found in related molecules, it is suggested that this may be ageneral feature of such molecules rather than that it is due to packing effects.A re-interpretation 312 of previous work 313 on the structure of ethyl stearateshows that the two unusual features, the COC and OCC angles, and thetrans disposition of the a carbon atom of the alcohol group relative to theC=O group, can be avoided by a different assignment of atoms to Fourierprojection peaks involving a change of space group from Aa to Ia.A three-dimensional refhement of the structure of salicylic acid showsdistortions of the benzene ring from hexagonal symmetry, and bond lengthswhich suggest that the quinonoid structure (52) is the major contribution tothe resonance form of the molecule.314 The carboxyl groups are inclined a t1.1" to the benzene planes, and pairs of hydrogen-bonded carboxyl groupsin adjacent molecules are in parallel planes 0.15 A apart.A similar feature isretained in the structure 315 of aspirin (acetylsalicylic acid) where the twocarboxyl planes are 0.119 A apart. In this structure the carboxyl group istwisted about 2" from the plane of the ring, and the acetyl group is notcoplanar with the salicylic acid residue. There is no obvious explanation308 C. K. Johnson, Actu Cryst., 1965, 18, 1004.30s J.Housty and M. Hospital, Acta Cryst., 1965, 18, 693.810 J. Housty and M. Hospital, Acta Cryst., 1965, 18, 753.3 l 1 J. H. Durnbleton and T. R. Lomer, Acta Cryat., 1965, 19, 301.318A. McL. Mathieson and H. K. Welsh, Acta Cryst., 1965, 18, 953.313 S. Aleby, Acta Cryst., 1962, 15, 1248.314 M. Sundaralingham and L. H. Jensen, Acta Cryst., 1965, 18, 1053.315P. J. Wheatley, J . Chem. Soc., 1964, 6036H . M . POWELL, C . K . PROUT, S. C . WALLWORK 587for the angular distortions observed, especially, in the acetyl group. Potas-sium hydrogen phthalate, C,H,(C02H)C02-K+, is another acid salt inwhich distinguishable carboxyl and carboxylate groups are joined by a shortintermolecular hydrogen bond (length 2.546 8) .316 Steric hindrance causesthe two carboxyl groups to tilt slightly out of the plane in opposite directionsand to twist away from each other through angles of 31.7" for the un-ionisedgroup and 75.4" for the ionised group compared with 33" for each of the twoequivalent carboxyl groups in phthalic acid itself.Distortion also occurs inthe exocyclic angles a t the point of attachment of the C0,- group. Theseare 123" in the direction of the other carboxyl group and 118" on the oppositeside.Two structures of peroxycarboxylic acids are reported. Although theextra flesibility of the additional oxygen atom might permit the formationof intramolecular hydrogen bonds, none is formed in either peroxypelar-gonic acid, (Me-[CH,1,.C0,H),317 or o-nitroperoxybenzoic acid.318 Thehydrogen- bonding in these two structures is intermolecular and takes theform of infinite spirals and infinite chains, respectively. It is likely, however,that on melting, conversion into intramolecular hydrogen-bonding takesplace.In both structures the molecules are non-planar ; in peroxypelargonicacid there is a twist towards the end of the aliphatic chain which causes theCOO group to be a t 34" to the main plane of the carbon chain; in o-nitro-peroxybenzoic acid the COO plane makes an angle of 58" with the plane ofthe ring and the nitro group is also twisted 28" out of the ring plane. How-ever, the conformation of the peroxycarboxyl group seems to depend uponthe hydrogen-bonding requirements. The crystal structures of the m- andp-bromoderivatives of methyl cinnamate (53) have been determined 319 inorder to correlate them with the solid-state photochemical reactions whichthey undergo.In both structures, the C=O group is found to be cis withrespect to the C=C bond. This allows the C*CO&e group to be almostcoplanar with the rest of the molecule; this conformation would be hindered,with consequent loss of conjugation, by a trans arrangement. The maindiEerence between the two structures is in the manner of packing of C=Cgroups relative to each other in adjacent molecules, and this gives rise todifferent solid-state photochemical reactions. The hydrogen-bonding of thenitrogen atoms is the main interest in the structure of picolinic acid hydro-The planar molecules are linked into zig-zag chains by NH...Cland OH-..Cl hydrogen bonds of lengths 3.105 and 3.005 A, respectively.The316 T. Okaya, Acta Cryst., 1965, 19, 879.s17 D. Belit,skus and G. A. Jeffrey, Acta Cryst., 1965, 18, 458.a18 M. Sax, P. Beurskens, and S. Chu, A d a Cryst., 1965, 18, 252.319 L. Leiserowitz and G. M. J. Schmidt, Acta Cryst., 1965, 18, 1058.320 A. Lament, Acta Cry8t., 1965, 18, 799588 CRYSTALLOGRAPHYlength of the NH-Cl hydrogen bond is consistent with the fact that eachN+ is forming one hydrogen bond and each C1- is acting as an acceptor fortwo hydrogen bonds. Other short contacts in this structure are mentionedin a later section. In the structure of nicotinic acid hydrochloride,HO ,C*C,H,*NH+C1-,321 the NH+ group forms a bifurcated hydrogen bondto both the oxygen atom of an adjacent nicotinic acid molecule and a chlorideion, which in turn is hydrogen-bonded by the OH of the adjacent molecule.This hydrogen-bonding links the molecules into infinite chains.Acyclic Compounds.-The crystal structures of sodium methoxide andsodium acetylenediolate, NaOC=CONa, have both been determined frompowder photographs.In the sodium methoxide structure,322 the sodiumatoms lie in a plane and are surrounded by methoxide groups above andbelow the plane such that four oxygen atoms are co-ordinated to each sodiuinand vice versa; d(Me-0) = 1-41 -+ 0.04, d(Na-0) = 2.32 -I= 0.015 8,LMeONa = 110.6". The sodium acetylenediolate structure is found 323 tobe isotypic with that of the K+, Rb+, and Cs+ acetylenediolates previouslyinvestigated, and contains linear -0-CrC-O- ions withd(C-C) = 1-19 & 0.3 8, d(C-0) = 1.37 & 0.3 8.Further details have beenreported for two carbanion structures. In ammonium tri~yanomethide,~~~d(C-C) = 1-40 -J= 0.01 and d ( e N ) = 1.15 & 0.01 A. Each CCN group islinear and 3" from the plane perpendicular to the molecular three-fold axis.The C-C bonds are somewhat shorter than the expected 1-44 A for sp-sp2bonding. There is a similar configuration in pyridinium dicyanomethy-lide,325 where each CCN group is about 3" out of the plane of the C-pyri-dinium plane. The lengths of the bonds from the central carbon atom ared(C-C) = 1-41, d(C-N) = 1.42 A. The CCN groups are again linear withd ( C 3 ) = 1.13 A. Disorder in two carbonium ion structures preventedcomplete refinement.In the tri-p-methoxyphenylmethyl salts the novelanions HC1,- or HBr,- were disordered with water molecules in crystals ofthe tetrahydrate.s26 However, it could be established that the central C-Cbonds must be coplanar, or very nearly so, and that the phenyl groups aretwisted approximately 30" out of this plane. More accurate atomic positionswere obtained in the structure determination 327 of triphenylmethyl per-chlorate. Again the central C-C bonds are coplanar, d(C-C) = 1.45 8, andthe phenyl groups are twisted 32" out of the plane and show a slight tendencytowards a- quinonoid form. The ions are arranged in such a way that thecentral part of the carbanium ion is sandwiched between two equidistantdisordered perchlorate ions whereas the peripheral parts are near to acrystallographically different set of ordered perchlorate ions.The structureof guanidinium chloride 328 contains planar guanidinium ions, C(NH,),+,with C,, symmetry and d(C-N) = 1-323 & 0.004 8. NH-Cl hydrogen321 Chung Hoe Koo and Hoon Sup Kim, J . Korean Chenz. SOC., 1963, 7, 257.329 E. Weiss, 2. anorg. Chem., 1964, 332, 197.323 E. Weiss and W. Buchner, Chem. Ber., 1965, 98, 126.324 R. Desiderato and R. L. Sass, Acta Cryst., 1965, 18, 1.325 C. Bugg and R. L. Sass, Acta Cryst., 1965, 18, 591.326 P. Andersen and €3. Klewe, Acta Chem. Scad., 1965, 19, 791.327 A. H. Gomes de Mesquits, C. H. MacGillavry, and K. Eriks, Acta Cryst., 1965,32* D. J. Haas, D. R. Harris, and H.H. Mills, A4cta Cryst., 1965, 19, 676.18, 437H . M . POWELL, C . K . PROUT, S . C . WALLWORK 589bonds of length of 3.30 A link the ions in such a way that each C1- is co-ordi-nated by six nitrogen atoms belonging to 3 guanidinium ions. Two of theseguanidinium ions are coplanar, with C1- 0.54 A out of the plane, and theother guanidinium ion is approximately perpendicular to this plane. Apossible explanation of the strongly acid nature of tris( sulphony1)methanesis that resonance stabilisation of a planar carbanion facilitates the loss of thecentral hydrogen atom. The anion has been found previously to be planarin t'he ammonium salt, and the molecule is now found 329 to be tetrahedralwith LSCS = 110.8 0-4". The C-S bonds are formally single withd(C-S) = 1-83 & 0.01 8 compared with 1.70 8 in the ammonium salt.Refinement of the structure of triphenylmethyl bromide 330 confirms that,of the three molecules in the asymmetric unit, one has its phenyl groupstwisted in the opposite direction from those of the other two molecules, butit fails to establish the nature of the C-Br bonds because of inaccuracies dueto the diffraction and adsorption effects of the bromine atoms.In ethylene-diamine dihydrochloride,wl the NCCN skeleton is planar and trans withd(C-C) = 1-54, d(C-N) = 1.48 8, LCCN = 109". The three NH.421 hydro-gen bonds formed by each NH,+ group link the ions into a three-dimensionalnetwork.A refinement of the structure of formamidoxime has been carried out 332in order to locate the hydrogen atoms and resolve the ambiguity whichexisted between the alternative structures NH2*CH :N*OH andNH :CH*NH*OH.The molecule has the expected amidoxime configurationbut a substantial contribution to the resonance form from the hydroxyami-dine structure must be assumed to explain the observed bond lengths. Thesmall LCNO, 109.7', is consistent with other oxime structures and may bedue to repulsions involving lone-pair electrons. In the crystal structure 333of the metastable orthorhombic form of acetamide, the two separate mole-cules in each asymmetric unit are dimerised by a pair of NH.--O hydrogenbonds of length 3.014 and 2.971 A. These dimers are further linked byNH.-O hydrogen bonds into columns but the columns are not hydrogen-bonded together. By contrast, the stable, trigonal form has a three-dimen-sional network of hydrogen bonds.The structure of dithio-oxamide,33*though well refined using three-dimensional data, shows significant differ-ences in the C=S and C-N bond lengths in the two non-equivalent moleculesin the asymmetric unit. There is no obvious explanation for this. The meand(C=S), 1.649 8, is shorter than in related molecules, and the central C-Cbond of length 1.537 suggests little conjugation between the two halves ofthe molecule. Intermolecular NH-..S distances of 3.432 and 3.456 A mayindicate hydrogen bonds. The higher-melting form of iY-benzyl-N-methyl-thioformamide has been shown 335 to have the sulphur atom and the benzyl328 J. V. Silverton, D.T. Gibson, and S. C. Abrahams, Acta Cryst., 1965, 19, 651.330 C. Stora and N. Poyer, Compt. rend., 1965, 260, 1660.331 Chung Hoe Koo, Moon I1 Kim, and Chung So0 Yoo, J . Korean Chem. SOC.332 D. Hall, Acta Cryst., 1965, 18, 955.333 W. C. Hamilton, Acta Cryst., 1965, IS, 866.3 3 p P. J. Wheatley, J . Chem. Soc., 1965, 396.335 A. M. Piazzesi, R. Bardi, M. Mammi, and W. Walter, Ricerca Sci. Rend., 1964,1963, 7, 293.6, A , 173590 CRYSTALLOGRAPHYgroup in a trans configuration about the amide C-N bond, and, although thebond lengths are only approximate, since they are obtained from threeprojections, they are consistent with about 50% double bond character inthe C-N bond.The structure of allylthiourea has been determined 336 by the symbolicaddition procedure.The thiourea group is planar, with d(C=S) = 1.66 8,somewhat smaller than the corresponding distance in thiourea and some ofits derivatives. NH43 hydrogen bonds of length 3.36 8 link the moleculesinto continuous chains. The CSe bond length of 1.82 & 0.01 A found337in N-phenyl-N'-benzoylselenourea suggests resonance between the normalstructure and that involving Se--C=N+. The main deviation from planarityof the molecule is a 30" twist of the phenyl group of the benzoyl substituentout of the plane of the (C0)NC group. The NH.-.O hydrogen bonds oflength 2.59 A are unusually short, consistent with a positive formal chargeon NH. NH.-Se hydrogen bonds of length 3.83 A are also formed, probablyowing to the partial negative charge on Se.The S-C(pheny1) intramolecularcontact of 3-32 A may suggest some Se-S-H interaction, or may be merelytolerated by the molecule. In triuret, H,N*CO*NH*CO*NH-CO*NH,, thereseems to be more double-bond character in the C-NH, bonds of length1.322 A than in the C-NH bonds.33* Lack of conjugation with the centralCO group is also shown by its C=O length of 1.220 8. The molecule hasthree planar parts, with the two outer parts twisted in opposite directionsthrough 7.5" and 16", respectively, relative to the central N-CO-N plane.Intermolecular NH-.O hydrogen bonds of length 2.77 and 2.79 8 link themolecules into layers which are only held together by van der Wads forces.The absolute configuration established for the sulphoxide mustard oil (54)indicates that the (R)-configuration can be assigned to all naturally derivedmustard oils as well as to the glucosides from which they are derived.Theorganic ion is found to be non-planar in the structure 340 of semicarbazidehydrochloride, the N-N bond being 18.3" out of the plane of the rest of theHO W ~[cH,I,.NH.cs.NH~~~( 5 4)Me M eH - t H HH2N, ,N,+ - H2N* N,, .t3 H2N, N:+0 0- 6- NH3 $/ NH3 C' NH342% (5 5 ) 43% 15 %molecule. It is the out-of-plane terminal nitrogen atom which is the protonacceptor, and the bond lengths correspond to the resonance forms (55).The NH3+ group forms hydrogen bonds of lengths 3.111 and 3-052 A to two336 K. S. Dragonette and I. L. Karle, Acta Cryst., 1965, 19, 978.337 H. Hope, Acta Cryst., 1965, 18, 259.338 D.Carlstrom and H. Ringertz, Acta CTyst., 1965, 18, 307.339K. K. Cheung, A. Kjaer, and G. A. Sim, Chem. Comrn., 1965, 100.340 M. Nardelli, G. Farn, and G. Giraldi, Acta Cryst., 1965, 19, 1038H . M . POWELL, C. I(. PROUT, S. C. WALLWORK 591separate chloride ions and the N€€ group probably also forms an intermole-cular NH*-O bond.In the monoclinic form of phenylhydrazine hydrochloride, the N-N bondis about 67" out of the plane of the ring.341 The NH3+ group forms threehydrogen bonds, two to C1- and one to the nitrogen atom attached to thering of an adjacent molecule. The hydrogen atom belonging to this nitrogenatom may also form a weak hydrogen bond to C1-. The organic anion inpotassium syn-methyldiazotate, CH3N20-K+, is found to be planar and inthe cis Structures involving N-0 must contribute appreciably to theresonance form of the molecule because d(N-0) = 1.306 & 0-007 A.Thepharmacological action of the methonium bromides(CH,) ,N+[CH,],N+( CH,) ,,2Br-, is interesting in that maximum ganglionicblockage occurs a t n = 6 and maximum neuromuscular blockage a t n = 10.The crystal structures of their dihydrafes 343 show that both molecules arecentrosymmetric with fully extended chains but the arrangement of mole-cules in the crystal structures is different. A study of the intermoleculardistances and a comparison with those of pentamethonium iodide indicatethat the pharmacological action is not dependent upon the distance betweenthe nitrogen atoms of the molecules but upon the number of possible van derWaals contacts in comparison with the chain length.There is an interestingcontrast between the conformations of the chains in spermidine trihydro-chloride, H,N+[CH J ,N+H ,[CH,],N+H3,3C1- 344 and sL)ermine tetrahidro-chloride, H3N*[CH 2]3N+H ,[CH , JaN+H ,[CH 2]3N+H ,,4C1-.395 The formerhas the expected planar zig-zag conformation but in the latter there is aguuche conformation about each of the C-N bonds nearest to the centre ofthe molecule. This difference can possibly be ascribed to the NH-SClhydrogen bonding which occurs in both structures. However, in sperminephosphate hexahydrate, the normal extended zig-zag configuration again0ccurs34~ and the chain is almost planar except for the terminal nitrogenatoms which lie 0.19 A on either side of the plane.A crystal structure determination 347 of bromomalonic dialdehyde showsthat the molecule is in the enolic form, but the accuracy is not high enoughto distinguish between the enolic and the aldehydic ends of the molecule.Two further long-chain glyceride structures have been determined 31% 349and the general features of such structures have been reviewed.350~ 351Triglycerides occur as '' tuning fork '' molecules in double-chain layers.The p'-form is the more stable for lower odd triglycerides whereas the p-formis the more stable in the other members of the series studied.Diglycerideshave molecules orientated in opposite directions with respect to the glycerol341 Chung Hos Koo, Bull. Chem. SOC.Japan, 1965, 38, 286.342 R. Huber, R. Langer, and W. Hoppe, Acta Cryst., 1965, 18, 467.343 K. LonsdaIe, H. J. Milledge, and L. M. Pant, Acta Cryst., 1965, 19, 827.344 A. Damiani, E. Giglio, R. Puliti, and A. Ripamonti, J . Mol. Biol., 1965, 11, 441.a45 A. Damiani, A. M. Liquori, R. Puliti, and A. Ripamonti, J. Moll. Biol., 1965,346 Y . Iitaka and Y . Huse, Ada Cryst., 1965, 18, 110.347 G. Lundgren and B. Aurivillius, Acta Cham. Scand., 1964, 18, 1642.348 K. Larsson, Arkiv. Kemi, 1965, 23, 1.349 K. Larsson, Arkiv Kemi, 1965, 23, 23.360 K. Larsson, Arkiv Kemi, 1965, 23, 29.361 K. Larsson, ArJciv Kemi, 1965, 23, 35.11, 438592 C R Y S TALL 0 GRAPH Yresidue, and only one hydroxyl groups and one C=O oxygen atom participatein hydrogen bonding.Four optically active forms and five racemic formsof 1 -monoglycerides have been found. Separation into antipode crystalsoccurs when racemic mixtures crystallise rapidly. A mesomorphous phasewith a highly ordered molecular arrangement exists in 2-monoglycerides.Hydrogen bonds in monoglycerides are found only between OH groups. Itis suggested that the alteration in physical properties between even and oddmembers of long-chain compounds can be explained on the basis of thenature of the methyl end-group planes. The possible ways of packing infi-nitely long hydrocarbon chains having the extended trans configurationhave been enumerated352 in terms of the symmetries of their sub-cells.Considering only sub-cells that extend over no more than two rows ofchains, it is found that ten different sub-cells are generated when all thechain axes are parallel, and thirty-one when they are not parallel.The eightmodes of packing so far reported are all included amongst these, in six ofwhich the chain axes are parallel. Of these six, three have higher symmetrythan was previously assumed.Aromatic and Other Homocyclic Molecules.-The crystal structure ofcyclopentadiene has been determined353 from four sets of zero level datataken a t -150" c. The carbon ring is planar and the bond distances,although approximate, are in agreement with those previously determinedby electron diffraction. The molecules are arranged in centrosymmetricallyrelated pairs, and these pairs are then related by a screw axis.The moleculardimensions in the structure 354 of methyl phenyl sulphone show no evidenceof conjugation between the SO, group and the phenyl ring, the S-ringdistance being 1.82 A. This is in agreement with spectroscopic evidence andwith chemical behaviour. The sulphur atom lies 0.22 A out of the plane ofthe benzene ring and also causes a 0.14 A displacement of the carbon atomt o which it is attached. The crystal structure 355 of p-thiocyanatoanilineis not yet sufficiently accurately determined to elucidate the effects of thestrong electron acceptor (SCN) and donor (NH,) groups on the dimensionsof the phenyl ring, but at the present stage it is possible to say that the carbonatom of the thiocyanato group is linked by double bonds to both sulphurand nitrogen atoms, implying a partial negative charge on the nitrogen atomand a corresponding positive charge on the sulphur atom.This is in agree-ment with spectroscopic evidence. The structure of metanilic acid is un-usual 356 in that the benzene ring lies in a mirror plane and the SO,- andNH,+ groups are arranged symmetrically across the plane. Strong NH+--.O-hydrogen bonds of lengths 2.85, 2.84, 2.84 A in roughly tetrahedral orienta-tions from the C-N bond are consistent with the zwitterion form of thestructure. Reports on the crystal structures of all three crystalline forms ofsulphanilamide have appeared during the year.357-359 In each case, theSb2 E. Sergeman, Acta Cryst., 1965, 19, 789.353 G. Liebling and R. E. Marsh, Acta Cryst., 1965, 19, 202.L.G. Vorontsova, K~stalZograJiya, 1965, 10, 187..355 I. V. Isakov and Z . V. Zvonkova, Kristallogrufcya. 1965, 10, 194.356 S. R. Hall and E. N. Maslen, Acta Cryst., 1965, 18, 301.357 B. H. O'Connor and E. N. Maslen, Acta Cryst., 1965, 18, 363.358 M. Alleaurne and J. Decap, Acta Cryst., 1965, 18, 731.369 M. Alleaurne and 5. Decap, Acta Crpt., 1965, 19, 934H . M . POWELL, C . E. PROUT, S. C. WALLWORK 593amide NH, group forms two relatively strong hydrogen bonds to oxygenatoms on adjacent molecules, and the amine group forms either one or twoweaker hydrogen bonds. In the high-temperature y-form, one plane ofsymmetry of the tetrahedron formed by the sulphur atom is a t right anglesto the plane of the ring and the nitrogen and sulphur atoms attached to it.This symmetry is not found in the other two forms.Otherwise, the struc-tures differ mainly in the details of the hydrogen bonding. The increase insteric hindrance in N-p-bromophenylbenzenesulphonamides, on substi-tuting the ortho positions adjacent to the NH group, has been investigatedby determining the cry st al structures of N -p - br omophen yl -p - chlorobenzene -sulphonamide 360 and N - (1 -bromo-3,5-dimethylphenyl)benzenesulphona-mide.361 The angle between the p-bromophenyl group and the CNS planeis increased from 45" to 80" on methyl substitution. In both molecules,conjugation with this phenyl group is inhibited. Steric hindrance duet>o ortho-substitution also occurs in ~alicylamide.~~2 In this case, however, itis counteracted by intramolecular hydrogen-bond formation between theortho-hydroxy group and the oxygen atom of the amide group, so that theamide plane is only about 3" from the plane of the ring.In addition to thisintramolecular hydrogen bond, the molecules are dimerised by intermole-cular NH-.O hydrogen bonds of length 2.94 and the dimers are furtherconnected into infinite chains by similar links of length 3.05 between theNK, groups and the OH groups of adjacent molecules.Preliminary work on the crystals of 1 -chloro-3-nitrobenzene 363 andp-nitrobenzoic acid 364 has established that the former molecule is planarbut that, in the latter, the nitro group is twisted about 13.5" from the planeof the ring. Dimerisation of the p-nitrobenzoic acid molecules takes placein the usual way by hydrogen-bonding between the carboxyl groups.Thecc- and p-modifications of p-nitrophenol behave differently on irradiation.The a-modification gives an irreversible colour change, yellow to red,whereas the B-form is light-stable. The molecular dimensions in the two formsare very similar,365 and in both cases the nitro group is twisted slightly outo€ the plane of the ring. In both structures, hydrogen bonds from the OHto the nitro groups link the molecules into infinite chains but the crystallineforms differ in their other intermolecular contacts. It is interesting that the@-modification, although it is more light-stable, is less thermodynamicallystable than the a-form, in which the molecules make a smaller number ofcontacts with adjacent molecules.One additional CH-.-O interaction, inparticular, in the cc-form is thought to be responsible for the light-sensitivereaction. Molecules of 2-chloro-4-nitroanilins are overcrowded,366 and thestrain is relieved by the chlorine and amino substituents moving apart360 B. R6rat, G. Dauphin, H.-P. Gervais, A. Kergomard, and C. RBrat, Compt. rend.,1964, 259, 4251.361 B. RBrat, G. Dauphin, A. Kergomard, and C. RBrat, Compt. rend., 1965, 261,139.363 Y. Sasada, T. Takano, and M. Kakudo, Mem. Inst. Protein Res., Osaka Univ.,1965, 7 , 6.E. M. Gopalakrishna, 2. Krist., 1965, 121, 378.364 T. D. Sakore and L. M. Pant, Indian J . Pure Appl. Phys., 1965, 3, 143.36s P. Coppens and G. &;I. J. Schmidt, Acta Cryst., 1965, 18, 62, 654.866 A.T. McPhail and G. A. Sim, J . Chem. SOC., 1965, 227594 CRYSTALLOGRAPHYslightly in the plane of the ring so that the angle between the bonds con-necting them to the ring is increased to 62'30'. The nitro group is alsotwisted through 4'20' out of the plane of the ring. There are three unusualfeatures in the structure 367 of 1,3,5-triamino-2,4,6-trinitrobenzene. Theaverage aromatic C-C distance is 1.444 b, the average d(C-NH,) = 1.319 8,and there are six bifurcated NH-0 hydrogen bonds since each NH2 protonforms one intramolecular and one intermolecular link. Quinonoid resonancestructures involving C=NH must contribute significantly to the structure.In addition, there is evidence of disordered proton positions such that somemolecules have the protons attached to the NOz groups.The unusual thermalproperties (it sublimes with decomposition above 300' c) and general insolu-bility of this substance probably arise from the very complete intermolecularhydrogen-bonding. A related structure showing significant contributionsof ionic quinonoid structures to the resonance form of the molecule 368 is thatof NN-dimethyl-p-nitroaniline. This is shown by d(N-Cring) = 1.40 forthe nitro group, and 1-36 b for the dimethylamino group. This tendencytowards quinonoid structure is to be expected in view of the strong electron-donating and -accepting properties of the two substituents. Nevertheless,the molecule as a whole is not planar, the nitro group being twisted 2.8" andthe dimethylamino group 7.3' from the plane of the benzene ring.A similartendency toward quinonoid form might be expected in p-nitrophenyl azidebut this is not found,369 the benzene ring being almost a regular hexagonwith average d(C-C) = 1.382 8. Theoretical predictions that there shouldbe a bend at the first nitrogen atom and then a straight nitrogen chain areconfirmed except that there is an angle of 173.4" a t the central nitrogenatom. The CNN angle is 115.0" and the azide chain is twisted about 5.3"from the plane of the benzene ring.Another example of the tendency towards a quinonoid form by thecontribution of polar resonance structures is found in p-iodobenzonitrile.~70The interesting CN-*I interaction is discussed in a later section.An accuratestructure determination 371 of 7,7,8,8-tetracyanoquinodimethane (56) showsthat the molecule has essentially mmm symmetry and that bond distancesare in good accord with the predictions of simple molecular orbital theory.There are small deviations from planarity, however, and the CCN groups arenot quite linear. A preliminary account 372 of the structure of 8,8-dicyano-heptafulvene, shows it to consist of planar molecules arranged parallel toeach other with an interplanar spacing of 3.4 8.Hydrogen-bonding by the phenolic OH groups in the isomorphousstructures of 4-bromo- and 4-methyl-2,6-di-t-butyIphenol is prevented byabric hindrance of the two t-butyl Apart from the hydrogenatoms, the molecules have mrn symmetry. Molecules of phloroglucinol867 H.H. Cady and A. C. Larson, Acta Cryst., 1965, 18, 485.8 6 8 T. C. W. Mak and J. Trotter, Acta Cryst., 1965, 18, 68.s6n A. Mugnoli, C. Mariani, and M. Simonetta, Acta Cqpt., 1965, 19, 367.870E. 0. Schlemper and D. Britton, Acta Cryst., 1965, 18, 419.STIR. E. Long, R. A. Sparks, and K. N. Trueblood, Acta Cryst., 1965, 18, 932,8'8 H. Shimanouchi, T. Ashida, Y. Sasada, M. Kakudo, I. Murata, and Y . Kitahara.Bull. Chem. Soc. Japan, 1965, 38, 1230.878M. Maze and C. Rhrat, Compt. rend., 1964, 259, 4612H . M . POWELL, C . I(. PROUT, S . 0. WALLWORK 695(1,3,5-trihydroxybenzene) are n~n-planar.~'* The three oxygen atoms are alldisplaced slightly in the same direction, from the plane of the benzene ring,0 5 0X OH(56) (57)towards the oxygen atoms on adjacent molecules to which they are hydrogen-bonded in forming infinite spirals of molecules.Only chloranilic acid(57; X = Cl) out of three hydroxy-quinone derivatives studied 376 appearsto be in the quinonoid form. Nitranilic acid (57; X = NO,) has a structureresembling that of the &-negative chloranilate ion as found in the ammoniumsalt, with equal C-0 distances, four C-C distances of about 1-42 A and twoof about 1.56 A in the ring. This acid probably exists as nitranilate ionsand oxonium ions in the solid state. Tetrahydroxy-p-benzoquinone (57;X = OH) molecules have the expected quinonoid structure in crystals ofthe dihydrate 376 with d(C=O) = 1.229 A and d(C=C) = 1.342 8. The mole-cules are linked into infinite chains by centrosymmetrically related pairs ofhydrogen bonds with d(OH-O=C) = 2.744 A.The hydroxyl groups notinvolved in this hydrogen-bonding form further links to hydrogen-bondedchains of water molecules. The glistening black colour of the crystals isthought to be due to charge-transfer self-complexing involving interactions,between the CO groups, which are discussed in a later section.A redetermination 377 of the structure of hexa(bromoethy1)benzene showsthat the benzene nucleus is not quite planar and the CH,Br groups are notexactly in the planes of symmetry perpendicular to the ring. 4-hydroxy-and 4,4'-dihydroxy-thiobenzophenone both form red crystals whereas mostthiobenzophenone derivatives range in colour from blue to green. However,the suggestion that the red colour is due t o strong hydrogen-bond formationbetween the phenolic OH and the sulphur atom of a neighbouring moleculeis not supported by the crystal structure determination 378 of 4,4'-dihydroxy-thiobenzophenone monohydrate.No phenolic OH***S hydrogen bond isformed ; instead, the hydrogen-bonding is through water molecules, thesulphur atom forming a weak HOH-S hydrogen bond of length 3.37 A.The two benzene rings are rotated by about 47" and 30°, respectively, fromthe plane of the central group. In the crystal structure of benzil, the mole-cules are formed into three-fold helices but are held only by van der Waalsforces.379 Each benzene ring makes an angle of 7" with its adjacent C(C0)Cplane and 76" with the other benzene ring; the two C(C0)C planes are at68" to each other.The two phenyl groups at the opposite ends of the buta-diene chain in cis,cis-l,2,3,4-tetraphenylbutadiene are conjugated with the374 K. Maartmann-Moe, Acta Cryst., 1965, 19, 155.37sE. K. Andersen, A d a Chem. Scand., 1964, 18, 2012.876 H. P. Klug, Acta Cryst., 1965, 19, 983.378 C. J. Brown and R. SadeLnaga, Acta Cryst., 1965, 18, 158.M. P. Marsall, Acta Cryst., 1965, 18, 851.Li. M. Manojlovic and J. G. Edmunds, Acta Cryst., 1965, 81, 543596 CRYSTALLOGRAPHYchain but are twisted through 34" out of its plane.380 The other two phenylgroups which are not conjugated with the chain are twisted out of the planethrough an angle of 75" in such a way that the dihedral angle between thefwo types of phenyl ring is 69".The bond distances within the butadienechain show the usual effects of conjugation.Although the structure determination 381 of 1,5-dimethylnaphthdeneindicates a slightly distorted molecule, owing to steric effects, the result,sshould be accepted only with reservations because they were determinedfrom two projections. Location of the hydrogen atoms as peaks in a differ-ence Fourier map suggests that the methyl groups are not rotating. Themolecular overcrowding in 3-bromo- 1 $-dimethylnaphthalene is relivedmainly by displacement of the methyl groups within the mean plane of thenaphthalene skeleton,382 the exocyclic angles at the points of attachment ofthe two methyl groups being enlarged to 124" and 123", respectively, in thedirections facing each other.In addition, there are some in-plane distortionsof the naphthalene nucleus and some small but definite departures fromplanarity. A similar overcrowding occurs 383 in the structure of 1,Ei-dibromo-4,8-dichloronaphthalene and it is relieved in a similar way. On the average,the exocyclic angles to the chlorine atoms are increased more (to 126") thanthose to the bromine atoms (124)". Statistical disorder which takes theform of a fraction 0.7 of one molecular orientation and 0.3 of its lateralinversion, prevents the accurate determination of the conformation of themolecules. The metastable modification of @-naphthol is isomorphous withna~hthalene,3~~ implying that the crystal structure is disordered with astatistical centre of symmetry.Phase transformation to the stable formmust involve a 180" rotation of about half the molecules in the cell.The crystal structures of naphthaquinone 385 and a number of its 2- and2,3-derivatives have been reported, the interest in these compounds arisingfrom the fact that some of them exhibit either vitamin K or anti-vitamin Kproperties. In a-naphthaquinone itself the C(2)-(3) bond length of 1.31 Asuggests a localised double bond ; the corresponding bond on the oppositeside of the quinonoid ring is of length 1.39 A because it also forms part of theconjugation system of the benzenoid ring. Similar distances (1.32 A and1-40 A), respectively) are found 386 in 2-bromo-l,4-naphthaquinone. Thereis some evidence of non-equivalent carboxyl groups and a close approach ofone of them to a bromine atom of an adjacent molecule, but in the absence ofestimated errors the validity of this cannot be assessed.The bond lengths inthe 2 - chloro-3 - hydroxy-387 and the 2 - c hloro- 3 -amino -derivat ives 38 suggestthat tautomerism occurs involving a transfer of the proton, from the OHgroup or the NH, group, to one of the quinonoid oxygen atoms, thus causingthe C(Z)-C(3) bond to become formally single. It is suggested that both380 I. L. Karle and K. S. Dragonette, Actu Cryst., 1965, 19, 500.381 J. Beintema, Acta Cryst., 1965, 18, 647.382 M. B. Jameson and B. R. Penfold, J . Cliem. SOC., 1965, 528.383 M. A. Davydova and Yu. T. Struchkov, Zhur. strukt. Khim., 1965, 6, 113.384 P.Coppens and I. Heairfield, Israel J. Chent., 1965, 3, 25.385 J. Gaultier and C. Hauw, Actu Cryst., 1965, 18, 179.386 J. Gaultier and C. Hauw, Actu Cryst., 1965, 18, 604.387 3. Gaultier and C. Hauw, Actu Cryst., 1965, 19, 580.388 J. Gaultier and C. Hauw, &4ctu Cryst., 1965, 19, 585H . M . POWELL, C . K. PROUT, S. C. WALLWORK 597tautomers occur, randomly distributed, in these crystals. In both structures,an intramolecular hydrogen bond is formed from the OH or NH, group to theadjacent quinonoid oxygen atom, and in each case the same proton is alsoinvolved in an intermolecular hydrogen bond. In 2-methyl-3-hydroxy- 1,4-naphthaquinone (phthiocol), there is no evidence of tautomerism within thecrystal; the C=O and GOH bonds have the normal values 1.21 and 1.36 A,respectiveIy.389 There are also differences in the hydrogen-bond system andin the stacking of the molecules by comparison with the Z-chloro- compound,and it is presumed that the similarity of molecular structure combined withslight dBerences in intermolecular bonding capabilities cause phthiocol tobe a vitamin K and the chloro-compound to be an anti-vitamin K.Structuredeterminationa9* of the leaf pigment, cordeauxiaquinone, has established thepositions of the substituents in the naphthazarin skeleton. The most likelytautomeric form is that with hydroxyl groups in the 4,8-positions.Attempts to refine the disordered structure of azulene, excluding someof the assumptions previously made, have led to an unsatisfactory struc-ture 391 in which there is still strong interaction between the positionalco-ordinates of the disordered pairs.The final R value of 6.9% (6.5%omitting non-observed reflections) is about the same as before. The studyis not encouraging in that it casts doubt on the results of any investigationshaving disorder. The structure of pyrene has been redetermined,392 usingnew three-dimensional data, in order to compare bond distances with thosepredicted by the valence-bond and molecular-orbital calculations, and thegeneral variation of dimensions is satisfactory. In detail, however, theagreement is not very good. In particular, the shortest bonds in the mole-cule have d(C-C) = 1.32 A, and this is less than the value calculated byeitpher method.The molecule is slightly non-planar, probably as a result ofcrysta,l-packing forces. The peripheral carbon atoms in 2,7-diacetoxy-15,16-diliydro-trans- 15J6-dimethylpyrene (58) constitute a novel aromatic systemof 14 n-electrons surrounding the two C-methyl groups. The structure wasdetermined393 from two sets of data refined independently, one at roomtemperature with a scintillation counter and the other at -130" c withWeissenberg photographs. In general, there is good agreement between thedimension a t the two temperatures but, surprisingly, the central C( 15)-C( 16)bond appears to be shorter at the higher temperature. The peripheral bondsystem of the pyrene nucleus is approximately planar with d(C-C) = 1.395 8.389 J. Gaultier and C.Hauw, Acta Cryst., 1965, 19, 919.390 M. Fehlmann and A. Niggli, Helv. Chim. Acta, 1965, 48, 305.301 G. S. Pawley, Actu Cryst., 1965, 18, 560.392 A. Camerman and J. Trotter, Actu Cryat., 1965, 18, 636.303 A. W. Hanson, Actu Cryst., 1965, 18, 599598 CRYSTALLOGRAPHYThe carbon atoms C(l5) and C( 16) are each 0.358 8 out of this plane and theacetoxy groups are approximately at right angles to the plane. 2,7-Dimethyl-perhydropyrene has a nucleus with the all-chair conformation and with themethyl groups in equatorial positions.394 The crystal structure determina-tion s95 of cyclo-octatetraenecarboxylic acid shows the molecule to have thetub form with DZd symmetrywith alternatingc-C bond lengths 1.322 and1.470 A and with a mean valency angle in the ring of 126.4".The bondjoining the carboxyl group to the ring is bent away from the plane containingthe C=C adjacent to it so as to be more nearly parallel to the molecule as awhole. The molecules are hydrogen-bonded into dimers in the usual way.Octaphenylcyclo-octatetraene shows a similar bond alternation 396 withaverage lengths of 1.493 and 1.343 8. The difficulty of accommodatingeight benzene rings results in small but siflcant angular distortions atthe points of attachment. By contrast, the molecules of C18lannulene aresituated at crystallographic centres of ~ymmetry,~~7 so the structure withalternate long and short C-C bonds is ruled out. Instead, there are two typesof bond arranged according to 3 symmetry; twelve inner bonds of meanlength 1.382 8 and six outer bonds of length 1.419 8. Repulsions betweenneighbouring internal CH groups cause displacements of atoms from themean plane by up to 0.085 8.Molecules of 2,2-dichloro-3-phenylcyclobut-3-enone are found 398 to bealmost planar apart from the two chlorine atoms, and the 'bond distancessuggest a considerable degree of conjugation between the benzene ring andthe cyclobutenone group.This probably accounts for the stability of this andsimilar compounds. Strain is to be expected in the benzene ring of benzo-(1,2: 4,5)dicyclobutene, due to its fusion with two cyclobutene rings. Thisis found 399 in the distortion of the angles in the ring to 126" at the points ofattachment of the cyclobutene rings. In addition, the bond in each four-membered ring remote from the points of fusion is elongated to 1.58 8,and this probably accounts for its thermal lability.In spite of this strain,the molecule retains planarity. The crystal structures of octachlorocyclo-butane and the centrosymmetric isomer of 1,2,3,4-tetraphenylcyclobutanehave both been refined further 400 because of the importance of the bondlengths in these cases where the cyclobutane ring is not part of a condensedpolycyclic system, nor is there endo- or exo-cyclic unsaturation associatedwith the ring. I n the octachloro-ccmpound, the bond lengths are now3-57 & 0.03 and 1.58 & 0.03 8, and in the tetraphenyl compound the twolengths are 1.573 & 0.015 and 1-566 & 0.015 8. In both cases the cyclo-butane ring is square, within experimental error, and the bonds are still longcompared with the normal single C-C distance.An interesting variation of894 A. Immirzi, Adti Accad. naz. Lincei, Rend. Classe Sci. $8. mat. not., 1964, 37,178.89s D. P. Shoemaker, H. Kindler, ITT. G. Sly, and R. C. Srivastava, J . Amy. Chem.SOG., 1965, 8'7, 482.S a S P . J. Wheatley, J . Chem. SOC., 1965, 3136.897 J. Bregman, F. L. Hirachfield, D. Rabinovich, and a. M. J. Schmidt, Ada Cryst.,398 I. L. Karle and K. Britks, 2. Krist., 1965, 121, 190.399 S. G. G. MacDondd, J. Lawrence, and M. P. Cava, Chem. and Iud., 1965, 86.400 T. N. Margulis, Acta Cryst., 1965, 19, 857.1965, 19, 227H. M . POWELL, C . K . PROUT, S. C . WALLWORK 5 99the bond lengthening in the cyclobutane ring occurs *01 in the photodimer ofcyclopent-2-enone.(59). The two bridge bonds are enlarged to 1.59 A butthose which are common with the five-membered rings have the normallength of 1.54 8. The five-membered rings are not planar; the two atomsacross the ring from the CO groups being above and below the plane formedby the other three ring atoms and the oxygen atom.The molecule of bicy clohexylidene consists of two cyclohexane rings inthe chair conformation with a centre of symmetry at the midpoint of thedouble bond of length 1.332 8 linking There is a non-crystallo-0(55)00graphic mirror plane perpendicular to the plane of the six( 60)central carbonatoms and passing through the centre of each of the cyclohexane rings. Thereis some evidence of strain in the molecule by flattening of the chair confor-mations relative to their ideal configuration.The 3-bromo- and 7-bromo-derivatives of 2-methoxytropone differ remarkably in their dipole momentsand chemical behaviour. Crystal structure determinations 403 of bothisomers shorn that they differ mainly in the conformation of the methoxygroup. In the 3-bromo-isomer, it is between the position where it would beperpendicular to the ring and where it would be cis to the C=O group. Inthe 7-bromo-isomer, it is between the perpendicular and the trans positions.The configuration (60) with a planar central ring has been established 404for 1,4 : 5,$-dimethyleneperhydroanthraquinone. The minor distortions in[3,3]paracyclophane, C18HB0, suggest that there is comparatively littlestrain in this ~nolecule.~~~ The aromatic rings are bent about 6' at each endinto a shallow symmetrical boat form, and the 01 carbon atoms are bentfurther by an average of nearly 4".The two rings do not lie directly aboveone mother but are displaced by about 0.5 A from this position. The bondangles in the side-chain are slightly larger than normal, and so are the di-hedral angles, compared with those in normal butane. The shortest intra-molecular contacts are only slightly less than the van der Waals distances.The full account has appeared 406 of 1 -p-bromobenzenesulphonyloxy-methyl-Ei-rnethylbicyclo[3,3,l]nonan-9-ol, and the conformations and valencyangles of this and similar compounds containing five- and six-memberedrings have been discussed 407 from a geometrical point of view.It is shownthat in bicyclic systems where two five-membered rings share three corners,as in bicyclo[2,2,l]heptane compounds, approximately tetrahedral angles401 T. N. Margulis, Acta Cryst., 1965, 18, 742.403 K. SasvBri and 1\11. Lbw, Acta Cmjst., 1965, 19, 840.404 H. G. Norment, Acto Cryst., 1965, 18, 627.406P. K. Gantzel and K. N. Trueblood, Actu Cqst., 1965, 18, 968.406 W. A. C. Brown, J. Martin, and G. A. Sim, J . Chern, SOC., 1965, 1844.&07 G. A. Sim, J . Chern. SOC., 1965, 5974.K. Furukawa, Y. Sasada, A. Shimada, and T. Watanabe, Bull. Chern. SOC. Japan,1964, 37, 1871600 CRYSTALLOGRAPHYbetween the terminal bonds of the two two-atom bridges cause the valencyangles in the five-membered rings to be about 100" (as has been observedexperimentally). The flattening of the chair conformation in bicyclo[3,3,1]-nonane systems is also discussed in relationship to the valency angles.Valency angles less than the tetrahedral value are also observed 408 in thenorbornane nuclei of anti- 8- tricyclo[3,2,1 02,4]octylp- bromobenzenesulphonate(61 ; R = p-BrC,H4S02) and anti-7-norbornenyl p-bromobenzoate.Theangle a t the bridgehead, which was previously thought to be related to thesolvolytic activity of such compounds, is about 96" in both derivatives,though they show low and high activity, respectively. The molecular formulaand configuration of the saturated dimer, c8FI2, formed by thermal poly-merisation of hexafluorobutadiene, has been established 409 as (62) in whichthere is a puckered four-membered central ring with fused five-memberedrings on either side.The mean LCCC in the four-membered ring is 81.5"a,nd d(C-F) = 1-367 and 1.327 A for CF and CP, groups, respectively. Ada-mantane (tricyc10[3,3,1,1~~~]decane) undergoes a phase transition to atetragonal structure at -65" c but an X-ray study 410 a t - 110"c shows thatthe arrangement of the molecules in the structure is unchanged apart froma 9' tilt about the c-axis. The room-temperature form appears t o be dis-ordered in space group Fm3m rather than ordered in space groups F43m, aspreviously assumed. Congressane (63) crystallises in a cubic unit cell andhas a remarkably symmetrical structure 411 with the three-fold axis which isthe body diagonal of the molecule coinciding with the body diagonal of thecubic unit cell.All the C-C distances are near 1.5 A, and all the valencyangles are near to the tetrahedral value.Heterocyclic Compounds.-The crystal structure has been determined 412of 2- trichloromethy1-N- hydroxymethylethylenimine, C2H,NCH( CCl,)OH, anactive chemical mutagen. The three-membered aziridine ring approximatesto an equilateral triangle of side 1.49 and the exocyclic C-N bond is oflength 1.46 8. The molecules are held together in the structure by OH-..hThydrogen bonds of length 2.75 A. The aziridine ring in 7-(p-iodobenzene-sulphonyl)-7-azabicyclo[4,1 ,O]heptane is fused cis to the cyclohexane ring 413with fusion angles 122".The chair conformation of the cyclohexane ring isappreciably flattened a.nd the C-C distances in this ring are shortened to anaverage value of 1.49 A. The p-iodobenzenesulphonyl group is at an angleof 98.3" to the bicyclic system.408 A. C. MacDonald and J. Trotter, Acta Cryst., 1965, 18, 243; 1965, 19, 456.409 I. L. Karle and J. Karle, Acta Cryst., 1965, 18, 345.410 C. E. Nordman and D. L. Schmitkons, Acta Cryst., 1965, 18, 764.411 I. L. Karle and J. Karle, J . Amer. Chem. Soc., 1965, 87, 918.412 R. P. Shibaeva and L. 0. Atovmyan, Doklady Akad. Nauk S.S.S.R., 1968, 160,413 L. M. Trefonas and R. Majeste, J. Heterocyclic Chem., 1965, 2, 80.334H . 111. POWELL, C . K . PROUT, S . C . WALLWQRH 601The isomorphism of succinic anhydride with maleic anhydride has beenconfirmed 414 in spite of the different configuration arising from the lack of adouble bond.The main difference between the two structures is the non-planarity of the ring in succinic anhydride. A structure determination415of anemonin (64) by the symbolic addition procedure establishes that thetwo lactone rings are in the trans configuration and that the cyclobutanering has a bent configuration with a, dihedral angle of 152". Two poly-morphic forms of DL-homocysteine thiolactone hydrochloride have beenexamined 416 and found to have very similar structures with insignificantWerences in bond lengths and angles. The five-membered thiolactone ringis in the envelope conformation with the ,8 carbon atom displaced about0.7 from the plane of the other four ring atoms.A third crystalline formproved to be a mixture of the other two. Although the proton has not beenfound directly in the structure 4l7 of pyridine hydrogen nitrate, the mole-cular dimensions suggest that it is in the form PyH+*-ONO,-. The pyridinering is nearly a regular hexagon. The molecule of a-pyridoin (1,2-&-3-pyridylethane-l,2-diol) is found 418 to possess a centre of symmetry and tohave a planar tram configuration around the central C=C. The positions ofthe hydrogen atoms in the intramolecular hydrogen bonds between nitrogenand oxygen show that the molecule is in the enediol form. Preliminaryresults 419 of the structure determination of N-( a-glutarimido)-4-bromo-phthalimide enable the main structural features of the thalidomide moleculeto be inferred and compared 420 with those of nucleosides.The phthalimidtpart of the molecule is essentially planar and the glutarimide ring is non-planar with C(2') about 0.5 A out of the plane of the other ring atoms. Thecentral C-N bond lies nearly in the plane of the phthalimide residue and formsapproximately tetrahedral angles with adjacent bonds in the glutarimidepart. The two parts of the molecule are nearly perpendicular to each other.The stereochemistry shows a general resemblance to that of the nucleosidesand this may account for its biological effects. A determination,"l fromprojection data, of the crystal structure of 2,6-dimethyl-y-pyrone hydro-bromide monohydrate suggests that the proton has been added to the car-bony1 oxygen atom. It then forms a hydrogen bond of length 2.53 to thewater molecule which, in turn, is hydrogen-bonded to two bromide ions.411 M.Ehrenberg, Acta Cryst., 1965, 19, 698.016 R. M. Moriarty, C. R. Romain, I. L. Karle, and J. Karle, J . Amer. Chem. SOC.,416 S . T. Freer and J. Kkaut, Acta Cryst., 1965, 19, 992.417 A. J. Serewicz, B. K. Robertson, and E. A. Meyers, J . Phys. Chem., 1965, 69,'18 T. Ashida, S. Hirokawa, and Y. Okaya, Acta Cryst., 1965, 18, 122.410 N. Furberg and C. S. Peterson, Ada Chern. Scand., 1965, 19, 283.O Z 0 S . Furberg, Acta Chent. Scand., 1966, 19, 1266.4Z1 H. Hope, Acta Chern. Scan#d., 1965, 19, 217.1965, 87, 3251.1915.602 CRYSTALLOGRAPHY3-bromo-4-hydroxycoumarin is another anti-vitamin K.The crystal struc-ture 422 of its monohydrate shows planar molecules with probably a randomdistribution of both tautomers (65), in the lattice. The structure is fullyhydrogen-bonded and the molecules are stacked on top of each other withinterplanar spacings of 3-42 A in two crystallographically independentcolumns. The molecular interactions in this structure are mentioned in alater section. The higher-melting isomer 2- chloro-9 - (CL) -dime thylamino-propylidene) thioxanthen is physiologically highly active. Contrary to pre-vious suggestions, it is found 423 to have the side-chain in the cis configura-tion relative to the chlorine atom. The adduct formed by reaction of tetra-cyanoethylene with N-ethoxycarbonylazepine is shown by crystal structuredetermination 424 of its methoxybromide to be (66).Structure determination 425 of the hydrobromide of 3-methoxycarbonyl-trans-3,5-dimethyl-A l-pyrazoline reveals the interesting resonance structure(67) in which conversion from a Al- to a A2-pyrazoline has occurred on form-ing the hydrobromide.The molecule is unusual in lacking a formal doublebond in the ring and in being non-planar. In DL-allantoin,(C,H2N,0,)NH*CO*NH,, the plane of the hydantoin residue makes an angleof about 80" with the plane of the side-chain 426 and the terminal NH, groupis arranged trans to the ring round the peptide-like bond. NH-.O hydrogenbonds of length 2.920 link like molecules (all D or all L) into infinite spirals,and further NH...O hydrogen bonds of length 2.827 A join unlike moleculestogether in pairs across centres of symmetry.2,2'-pPhenylenebis-( 5-phenyloxazole) is a strong organic scintillator. In its crystal structure,427the central phenyl ring occupies a centre of symmetry and the two adjacentoxazole rings are twisted relative to it through 3.75" m opposite directions.Each terminal phenyl group is twisted through a further 6.45" in the samesense as its adjacent oxazole ring, resulting in a propeller-shaped molecule.Me MeNH t iThe bond lengths indicate mainly localised C=C and C=N bonds in the five-membered rings but also indicate appreciable conjugation between the rings.422 J. Gaultier and C. Hauw, Acta Cryst., 1965, 19, 927.423 J. D.Dunitz, H. Eser, and P. Strickler, Helv. Chim. Acta, 1964. 47, 1897.424 J. H. van den Hende and A. S. Kende, Chem. Conam., 1965, 384.425 H. Luth and J. Trotter, Acta Cryst., 1965, 19, 614.426 D. Mootz, Acta Cryst., 1965, 19, 726.427 I. Ambato and R. E. Marsh, Acta Cryst., 1965, 19, 942H . M. POWELL, C. K . PROUT, S. C. WALLWORK 603Two structures have been investigated in which the ring-closure whichsometimes occurs in nitroso- and nitroxy-compounds does not take place.The molecule of 1- (4-chlorobenzyl)-2- (4,5-dihydro-Z-imidazolyl) - 1 -nitroso-hydrazine is found 428 in the normal N-nitroso form with d(N-0) = 1.250 A,in crystals of its monohydrate. However, the nitroso oxygen atom appearsto form an intermolecular CR-0 hydrogen bond with d(H-0) = 2.270 A.The nitroxy group in 2-0-( p-bromobenzenesulphonyl)-1,4 : 3,6-disnhydro-D-glucitol 5-nitrate (68) forms a rather close intramolecular contact 429 of2.9 with the oxygen atom in the adjacent ring.Since this conformationis adopted, from a number of possibilities, it suggests that there is an attrac-tive force between the relatively negative nitro oxygen and the relativelypositive ring oxygen.The structures of two tetrachlorophenazines have been examined.43uThe 2,3,7,8-compound is planar, within experimental error, with normalintermolecular contacts, but the 1,4,9,9-compound has the chlorine atomsslightly out of the plane of the molecule and these also show intermolecularcontacts slightly below the expected van der Waals distances.A refine-ment 431 of the structure of asym:@-naphthazine shows that the moleculeis planar, and confirms the expectation that the valence angle of the hetero-cyclic nitrogen atom is less than 120" ( LCNC = 116'). The molecule oftetracya8no-ly4-dithiin (69) is folded about a line through the two sulphuratoms 432 and there is a dihedral angle of 124" between the two planar halves.The S-C distance of 1.755 A suggests that there is some resonance involvingthe sulphur atoms. The molecules are arranged in such a way that one edgeof each molecule fits into the fold of an adjacent molecule, making a numberof close N..-C contacts, whereas the other edge is adjacent to the convexsides of two neighbouring molecules and forms no contacts less than 3-4 8.The molecule of trans-2,3-dichloro- 1 ,.l-dithian has a conformation 438 similarto the corresponding dioxan compound wlth the ring in the chair form andthe chlorine atoms in axial positions.The chair conformation occurs 434 inthe rings of the 3,6-dicarboxylic acids of 1,2-dithian and 1,2-diselenan. Inboth structures, the carboxyl groups are in equatorial positions but therotation relative to the adjacent part of the ring is different in the twocompounds owing to the increased steric effect of the selenium atoms.The S-S distance is 2.07 & 0.02 A and the Se-Se distance is 2-32 & 0.02 A.The molecules are hydrogen-bonded through their carboxylic groups infoinfinite chains of alternate right- and left-handed molecules but the relativepositions of right- and kft-handed molecules in adjacent chains are differentin the two compounds.The modi-fications of the normal benzene ringdimensions observed 435 in the structure of 2$-diphenylthiadiazole areconsistent with the thiadiazole ring acting as an electron a,cceptor, though428 G. J. Palenik, Acta Cryst., 1965, 19, 47.42B A. Cameman, N. Camerman, and J. Trotter, Acta Cryst., 1965, 19, 449.430 V. Riganti, S. Locchi, R. Curti, and B. Bovio, J. Hete.rocyclic Ckem., 1965, 2,481 B. Bovio and 8. Locchi, 2. Krist., 1965, 121, 306.432 W. A. Dollase, J. Anaer. Chem. SOC., 1965, 87, 979.433 H. T. KaH and C. Romers, Acta Cryst., 1965, 18, 164.434 0. FOSEI, K. Johnsen, and T. Reistad, Acta Chem. Scand., 1964, IS, 2345.436 Z. V. Zvonkova and A.N. Khvatkina, KristaEEograjZya, 1965, 10, 734.87, 176604 CRYSTALLOGRAPHYnot as powerfully as a nitro group. The crystal structure determina-tion 436 of 3,4-dibenzyl-2-p-methoxyphenyl-l,3,4-thiadiazolidine-5-thione(70; R = benzyl, R' = p-methoxyphenyl) confirms that the reaction ofNN'-dialkylhydrazines with aromatic aldehydes and an unsaturated com-pound (in this case, CS,) takes place by a 1,3-&polar cycloaddition. Thethiadiazolidine ring is not planar and is rather asymmetric since the lengthsof the two C-N bonds are quite different, as are also the two C-S bonds. Thisinequality is thought to arise by delocalisation of the electrons from theC=S group into the adjacent bonds. Structure determination*37 of thebis-p-bromoanilide of carbon dioxide biotin shows that the CO, is attachedto the biotin a t the nitrogen atom furthest from the valeric acid side-chain.The molecule has the unexpected, fdly-extended form, stabilised by inter-molecular NH-0 hydrogen bonds.Two possible models for triethylenedia-mine (71) are indistinguishable crystallographically 43* on the basis of agree-ment between observed and calculated structure factors. One model is centor-symmetric and implies spacegroup P63/m, and the other has one NCCH,],group twisted about 10" relative to the other, implying space-group P63.The vibrational infrared spectrum has been assigned, however, on the basisof the centrosymmetric model. An X-ray study 439 of 3,6-bis-spirocyclo-heptane-1,2,4,5-tetraoxacyclohexane (dimeric cycloheptanone peroxide)shows it to be similar to the previously studied "dimeric cyclohexanoneperoxide " with the central ring in the chair-form.A re-investigation,440 with three-dimensional data, of the crystal struc-ture of dialuric acid monhydrate confirms that the molecule is in the 5,6-dihydroxy form (72).As in the case of other oxypyrimidine and barbituricacid derivatives, the conventional formula is only an approximate descrip-tion of the molecule. In particular, the bond lengths show that C(6)-0(6)must have considerable double-bond character, and it can be assumed thatthe proton attached to this oxygen is the acidic one, especially since loss ofthis proton gives rise to a symmetrical ion. Isodialuric acid, to which theH Hp96 I.L. Karle and J. Karle, Acta Cyst., 1965, 19, 92.437 C. Bonamere, J. A. Hamilton, L. K. Shinrauf, and 5. Knappe, Biochemistry,G. S . Weiss, A. S. Parkes, E. R. Nixon, and R. E. Hughes, J. Chern. Phys.,1965, 4, 240.1964, 41, 3759.499 P. Groth, Acta Chem. Scand., 1964, 18, 1SOl.'40 W. Bolton, Acta Cryst., 1965, 19, 1051H . M . POWELL, C . K. PROUT, S. C . WALLWORK 606structure (72) has previously been ascribed, is more likely fo be in the2,4,5-triketo-6-hydroxy-form. Alloxan monohydrate (sometimes knownsimply as anoxan) is found 441 to be in the 2,4,6-triketo-5,5-dihydroxy form(73). The bond lengths and angles are those expected, apart from C(4)-C(5)and C(5)-C(6) which have a mean length 1639 8, significantly larger thannormal pyrimidine C-C distances. The molecule is non-planar with C(5)about 0.23 A out of the mean plane. Alloxantin dihydrate is found 442 to bein the triketopinacol configuration (74) with two molecules of water ofcrystallisation.Each half of the molecule shows a close resemblance toalloxan monohydrate, with long C-C bonds and the C(5) atoms out of theplane. The central C(S)-C(S') bond of length 1.55 A is longer than thatusually found between two benzene rings but is similar to the central bondin 2,2'-bipyridyl. A crystal structure determination 443 of the condensationproduct of alloxan monohydrate with the bromo-derivative of o-amino-diethylaniline shows it to have the unexpected form 5-(6-bromo-3-ethyl-2-methylbenzimidazo1ium)barbiturate. Both the benzimidazole and the barbi-turate nuclei are very nearly planar, and the dihedral angle between them is66.7 O in one molecule and 69.8" in another crystallographically independentmolecule in the unit cell.The substance generally known as alloxan tetra-hydrate has been found 444 to be 5,5-dihydroxybarbituric acid trihydrate.The C(5) atom carrying the two hydroxyl groups is 0.214 A out of the planeof the rest of the ring, and the carbonyl oxygen atoms are displaced slightlyfrom this plane in the opposite direction. In the potassium salt (75) of5,5-diethylbarbituric acid (veronal) the aromatic ring and the double ethy-lenic chain are each nearly planar 445 with an angle of 88" between the twoplanes. The molecular dimensions are consistent with the expected reso-nance forms of the molecule, mainly in the ketonic form.The pyrimidinering in 5-iodo-Zf-deoxyuridine is in the keto form,O*a and the atoms attachedto this ring show small deviations from planarity. The deoxyribose ring ispuckered with C(2') displaced 0.59 A from the mean plane of the other fouratoms. The angle between the mean planes of the two rings is 81" and theconformation is ccnti about the glycosidic C-N bond. Molecular interactionsin this structure which may be related to the antiviral activity of the mole-cule are discussed in a later section. The full account has been published 447of the crystal structure of isocytosine. Besides giving further detail of thehydrogen-bonding, which resembles the base-pairing of DNA, it reportsH Me441 C.Singh, Acta Cryst., 1966, 19, 759.44a C. Singh, Acta Cryst., 1965, 19, 767.443 B. W. Matthews, Ada Cryst., 1965, 18, 151.u4 D. Mootz and G. A. Jeffrey, Acta Cry&., 1965, 19, 717.*lli J. Berbhou, B. RBrat, and C. Rbmt, Acta Cryst., 1965, 18, 768.4p6 N. Csmerman and J. Trotter, Acta Cryst., 1965, 18, 203.447 B. D. Sharma and J. F. McCormell, Acta Cryst., 1965, 19, 797606 CRY STALLOQRAPHYnon-planarity of the non-ring atom in both tautomerio forms of the mole-cule in the crystal. The reaction product of an attempted synthesis of apyrimidine analogue of 1,5-benzodiazepines has been found,u* by crystalstructure determination, to be the amino-pyrimidine (76). The pyrimidinering and the side-chain lie in two separate planes, and the dimensions of theside-chain correspond to a mixture of ketonic and enolic forms due to eitherresonance or disorder.Two completely independent crystal structuredeterminations of purine, published together,a9 show Herences from eachother less than their standard deviations, apart from systematic differencesin the temperature factors. A proton is attached to N(7) of the five-mem-bered ring rather than to N(9). The molecules are planar and are joined byrelatively short N(7)H-N(9) hydrogen bonds of length 2.85 8. Protonationat the N(7) position has been established 450 in the crystal structure deter-mination of guanine hydrochloride dihydrate by location of the hydrogenatoms on Fourier difference maps. The molecules are linked into centro-symmetric dimers by NH-oN hydrogen-bonds from the amino group,attached to C(2), to N(3).The dimer is W e d by further hydrogen bonds tofour water molecules which are, in turn, hyhogen-bonded t o two chlorideions.The tautomeric form of 1,2,4-triazole which seems more probable from thehydrogen-bond arrangement in the crystal structure 451 is (77) with the pro-ton attached to N(2) rather than to N(4), though a disordered structurecontaining both tautomers cannot be ruled out. In s-triphenyltriazine (78),the three phenyl groups are twisted through angles 7.6", 10.9", and 6.9" withrespect to the plane of the triazine ring,4S2 the last-mentioned being a twistin the opposite sense from that of the other two. The bonds connecting thephenyl groups to the central ring are slightly out of the triazine plane and44* J.Silverman and N. F. YannOni, Acta Cryst., 1965, 18, 756.449 D. G. Watson, R. M. Sweet, and R. E. Marsh, Acta Cryst., 1965, 19, 573.450 J. Iball and H. R. Wilson, PTOC. Roy. SOC., 1965, A , 288, 418.451 H. Deuschl, Ber. Bunsmgmellschaft phys. Chem., 1966, 69, 550.452 A. Damjani, E. Giglio, and A. Ripamonti, Acta Cqst., 1965, 19, 161H . M . POWELL, C . K . PROUT, S . C. WALLWORK 607their average length of 1.475 b, together with the non-planarity of the wholemolecule, indicates incomplete conjugation between the triazine and thephenyl rings, due to steric hindrance. The structure of the reaction productof acrolein with ammonia has been established, by an X-ray study 453 of itstrihydrochloride hemihydrate, as dodecahydro-1,4,7,9b-tetra-azaphenalene(79) which has three-fold symmetry.In the crystal, each peripheral nitrogenatom is hydrogen-bonded to two neighbouring chloride ions. The structureof the self-condensation product of o-aminobenzaldehyde in the presence ofnickel ions has been determined:% by an X-ray structural study of its dini-trate dihydrate, to be the slightly propeller-shaped tribenzor 1,5,9]triaza-cycloduodecineniclcel( 11) ion (80). Either disorder or rapid interconversionof N-H tautomers is indicated by the bond parameters and the appearance ofhalf a hydrogen atom for each nitrogen atom in the crystal structure 455 ofporphine (81). Separate single and double bonds can be distinguished inthe peripheral bonds of the pyrrole rings, but bonds of intermediate lengthform a continuous inner ring which includes all the nitrogen atoms and thebridge bonds.These, therefore, constitute the main resonance system ofthe molecule containing 18 n-electrons. The structures of the dimethylesters of nickel@) 2,4-diacetyldeuteroporphyrin-IX 456 and methoxyiron(rn)mesoporphyrin-IX 457 have been determined. In discussing these structures,it is pointed out that there is likely to be angular strain in the o-bond patternof a strictly planar porphine skeleton but that the tendency to non-planaritywill be counteracted by the z-bonding. These conflicting effects result in askeleton which may be planar but which should be quite easily deformablein a direction normal to its mean plane.In the nickel(n) compound, theporphine skeleton is almost, but not exactly, planar, and in the methoxy-iron(m) compound, it is slightly domed. In the latter structure, the ironatom lies 0.49 d above the porphine skeleton, and the methoxy groupoccupies a, fifth co-ordination position. D and L-Isomers occur in a disor-dered way in the lattice. The difference between porphyrin and analogousphthalocyanine structures are attributable mainly to the difference in bondangle at the methine carbon atom (ca.125") compared with that at the cor-responding nitrogen atom (ca.117") in phthalocyanine. The porphyrin ringin a-chlorohsmin is slightly puckered 4 s and the two vinyl groups appear infour positions in the Fourier electron-density syntheses, owing either todisorder or to a lack of the assumed centre of symmetry in the structure.The iron atom is about 0.5 A above the plane of the four nitrogen atoms towhich it is bonded, in the direction of the chlorine atom which occupies theMth co-ordination position.The C ( 2 ) 4 ( 3 ) distances in each pyrrole residuecorrespond to a bond order of about 2.Natural Products and Related Compoands.-The conformations of thefuranose ring in nucleic acids and other carbohydrate derivatives have been453 A. E. Smith, ActaG Cryst., 1965, 19, 248.45433. B. Fleischer and E. Klem, Inorg. Chem., 1966, 4, 637.466 L. E. Webb and E. B. Fleischer, J . Amer. Chem. Soc., 1966, 87, 667.466 T. A. Hamor, W. S. Caughey, and J. L. Hoard, J . Anter. Cham. SOC., 1965, 87,d67 J.L. Hoard, M. J. Hamor, T. A. Hamor, and W. S. Caughey, J . Amer. Chm.460 D. F. Koenig, Acta Cryst., 1966, 18, 663.2305.SOC., 1965, 87, 2312608 CRYSTALLOGRAPHYreviewed 459 and typical dimensions deduced. A relationship is notedbetween the C-OH bond length and the CC(0H) bond angle. An accuratedetermination 460 of the crystal structure of a-D-glucose by neutron dlffrac-tion shows that the individual C-C, C-H, and 0-H bond lengths deviateonly slightly from their mean values 1-523, 1.098, and 0.968 8, respectively.However, the C(1)-0(1) bond length, 1.398 8, is significantly shorter thanthe other C-0 bonds which average to 1.420 8. The valence angle of thering oxygen atom is 113.8". A two-dimensional determination 461 of thestructure of p-D-glucose p - bromophenylhydrazone shows that the sugarcomponent has a pyranose chair conformation, so the compound is actuallya hydrazide.All the substituents in the sugar ring are in equatorial positionsand the azimuthal angle in the hydrazine group is about 100". The a-con-figuration at C(1) has been confirmed 4G2 in dipotassiuin glucose-l-phosphatedihydrate, and the dimensions of the esterified phosphate group agree withthose found in other sugar phosphates. The structure 463 of calcium 5-oxo-D-gluconate exhibits a lactol arrangement of the organic anion with an eight-fold co-ordination of Ca2+ by oxygen atoms a t the vertices of a regulartriakistetrahedron. Ring-closure between C(2) and C(5) has resulted in anon-planar furanoid ring with a new asymmetric centre at C(5) and a C(4),-C( 5) cis-diol configuration. A redeterminati~n!~~ from the original experi-mental data, of the crystal structures of a-D-glucosamine hydrochloride a,ndhydrobromide shows that the pyranose ring of the sugar has the expectednormal Sachse trans configuration with the conformation la2e3e4e5e.It isinteresting that the hydrogen-bonding is dominated by the NH,+ groups,and only one OH*.*O hydrogen bond is formed directly between sugar ions.Molecules of a-methyl D-galactoside 6-bromohydrin have the expected chairconformation 465 with the configuration lu2e3eh but, in contrast withmonosaccharides investigated hitherto, the C( 1)-O( 1) bond is not shortened.This is probably due to the replacement of the hydrogen atom of 0 ( 1 ) by amethyl group.Methoxymercuration of D-galactal could take place by eitherc k or trans addition to the double bond. Partial structure determination 4G6of the reaction product indicates that the ClHg and Me0 groups both occupyaxial positions in the six-membered ring, showing that the compound ismethyl 2-chloromercuri-2-deoxy-a-~-talopyranos~de and that it must haveresulted from trans-addition. Hydroformylation of tri- O-acetyl-D-glucalyields two isomeric products which can be deacetylated to give the parentpolyols. Structure determination 46 ' 9 46* of the p-bromobenzenesulphonylderivative of the isomer related to the lower-melting polyol shows it to be4,5,7 , - tri- O-acetyl-2,6- anhydro- 1 - 0- ( p - bromobenzenesulphony1) -3-deoxy- D -460 M.Sundaralingam, J . Anaer. Chena. Soc., 1965, 87, 599.4 6 o G . M. Brown and H. A. Levy, Science, 1965, 147, 1038.4rlT. Dukefos and A. Mostad, Acta Chern. Scand., 1965, 19, 685.482 C. A. Beevers and G. H. Maconochie, Acta Cryst., 1965, 18, 232.463 A. A. Balchin and C. H. Carlisle, Actu Cryst., 1965, 19, 103.464 S. S. C. Chu and G. A. Jeffrey, Proc. Roy. SOC., 1965, A , 285, 470.466 J. H. Robertson and B. Shedrick, Actu Cryst., 1965, 19, 820.46@ J. Bain and M. M. Karding, J . Chem. SOC., 1965, 4025.467 A. Cameman, H. J. Koch, A. Rosenthsl, and J. Trotter, C a d . J . Chm.,46* A. Cameman and J. Trotter, Acta Cryet., 1965, 18, 197.1964, 42, 2630H . N. POWELL, C . K . PROUT, S . C . W-4LLWORK 608gluco-heptitol, so the higher-melting isomer must be the correspondingmanno-heptitol.The sugar ring has the chair conformation with all thesubstituents in equatorial positions.A preliminary report 469 on the structure of L( +)-cysteine hydrochloridemonohydrate indicates that the carboxyl group is not ionised but possess anOH group. However, the tetrahedral arrangement 470 of hydrogen bondsround the nitrogen atom in the crystal structure of /?-alanine suggests thatthis molecule is in the zwitterion form. The carboxylate group is in a planeat 84" to the rest of the molecule. The organic ion in L-phenylalanine hydro-chloride 471 also consists of two planar parts, the phenyl group and theadjacent ethylene group forming one plane and the (un-ionised) carboxylgroup and its adjacent carbon atom forming the other.PJH+.--Cl- andOH-Cl- hydrogen bonds join the molecules into layers and these are con-nected to form double layers by means of bifurcated hydrogen bonds fromNH+ to C1- and 0. L-Arginine hydrochloride and hydrobromide are iso-morphous in form I but not in form 11. The crystal structure 472 of form Icontains two non-equivalent molecules and these agree well in their dimen-sions, which appear normal. The hormone serotonin is unstable, so it isusually isolated as a complex with creatinine sulphate, crystallising as amonohydrate. The structure of the complex determined 473 by the symbolicaddition procedure shows that, although the complex is tightly bound by anintricate network of hydrogen bonds, only one of these links the serotoninand creatinine components directly.The creatinine molecule is nearlyplanar and so is the indole portion of serotonin, but the atoms of its side-chain are progressively further out of the indole plane. Both organic com-ponents are protonated, resulting in a NH,+ group on serotonin and a=NH + roup on creatinine.An important advance in our understanding of enzymes and their modeof action has been achieved by the determination of the structure of henegg-white Iysozyme 474 a t 2 A resolution and of some of its inhibitor com-plexes 475 a t 6 A resolution. In the 2 A structure the main polypeptidechain can be recognised as a continuous ribbon of high density with charac-teristic features at regular intervals.In some regions, this clearly shows thea-helical conformation. Some of the side-chains can be recognised and, as nresult, most of the difficulties of the primary structure have now beenresolved. In the complexes, molecules which are competitive inhibitors ofIysozyme bind specifically to the same site in the enzyme whereas there is nospecific site for the non-inhibitors. The inhibitor molecules lie well embeddedin the enzyme molecule in a crevice in its surface, and the amino-acid residuesin this region of the lysozyme molecule can be identified. They include threetryptophans but not the single histidine residue in the molecule. The.g469 R. R. Ayyar and R. Srinivasan, Current Sci., 1965, 34, 449.470 P. Jose and L. $1. Pant, Acta Cryst., 1965, 18, 806.471 G.V. Gurskaya, Kristallografiya, 1964, 9, 839.472 S. K. Mazurndar and R. Srinivasan, Current Sci., 1964, 33, 573.473 I. L. Karle, K. S. Dragonette, and S. A. Brenner, Acta Cryst., 1965, 19, 713.474 C. C. F. Blake, D. F. Koenig, G. A. Mair, A. C. T. North, D. C. Phillips, and V. R.l i 6 L. N. Johnson and D. C. Phillips, Nature, 1966, 206, 761.Sarma, Nature, 1965, 206, 757610 C R Y S ‘I! ALL 0 C RL4PH Yfungal metabolite ferrichrome-A is a cyclic hexapeptide. An X-ray investi-gation *v6 has confirmed the amino-acid sequence and revealed a trans con-formation a t each peptide linkage. The absolute configuration of the threehydroxamate rings a t the iron atom is that of a left-handed propeller.of the crystal structure of cytidine shows that the cyto-sine part of the molecule is planar with dimensions similar to those found incytosine monohydrate.The C(4)-C(5) bond seems to be almost a puredouble bond and this may explain some of the reactions of cytosine and otherpyrimidines of the nucleic acids. The relative orientations of the pyrimidineand ribose rings correspond to an anti conformation. A similar relativearrangement of a, purine and a sugar ring is found478 in deoxyadenosinemonohydrate. The adenine group is planar but the carbon atom of theglycosidic bond is displaced by 0.22 A from this plane. The ribofuranosering is puckered with C(3) displaced 0.55 A from the plane of the other fourring atoms. All available groups participate in the hydrogen-bonding, themost interesting features of which are the infinite NH.-.N chains, and thedistorted trigonal arrangement of the OH.-O bonds formed by the watermolecule. Bivalent metal ions play a significant part in the combination andstructural relationships of proteins and nucleic acids.In the structure 479of D-( +)-barium uridine-5’-phosphate the two independent Bas+ ions eachhave ten oxygen-atom neighbours. The nucleotides pack together efficiently,with base planes nearly parallel but only partially overlapping. The con-formation about the C(5’)4(4’) bond in ribose derivatives and relatedcompounds is discussed, and it is noted that the C(5)-O(5’) bond is normallygauche to both C(4‘)-O( 1’) and C(4’)-C(3’). This, combined with the fact that,in B-ribo- and /?-deoxyribo-nucleotides, the glycosidic bond is on the sameside of the furanose ring as the C(4’)-C(5‘) bond, causes steric hindrancewhich favours the anti conformation of the two rings.An X-ray study 480of the A form of deoxyribonucleic acid largely eliminates the possibilitythat DNA molecules might have a left-handed configuration. The correct-ness of the Watson-Crick scheme for base-pairing is again confirmed; analternative proposal does not appear to be compatible with the X-ray data.Hunterburnine has been sh0~n,4~1 by the X-ray analysis of its /3-methi-odide, to be the f i s t example of a new class of indole alkaloid, having thenovel structure (82) for the methiodide. The conclusions reached in chemicalstudies have been confirmed,4*2 that mitragynine is an alkaloid containingthe indolo[2,3-a Jquinolizine ring system substituted with methoxyl, ethyl,and methyl /?-methoxyacrylyl groups, and also shows that the methoxy-carbonyl and the methoxyl groups have a trans corQuration about thedouble bond in the acrylyl moiety.In the quinolizine ring system, the ringfused to the indole position has a half-chair form while the other ring is in aA refinement476 A. Zalkin, J. D. Forrester, and D. H. Templeton, Science, 1964, 146, 261.477 S. Furberg, C. S. Petersen, and C. R~lmming, Acta Cryst., 1965, 18, 313.478 D. G. Watson, D. J. Sutor, and P. Tollin, Acta Cryst., 1965, 19, 111.480 W. Fuller, M. H. F. Wilkins, H. R. Wilson, and L. D. Hadton, J. Mol. Biol.,*81 J. D. M. Asher, J. M.Robertson, and G. A. Sim, J. Chm. Sm., 1965, 6355.488 D. E. Sacharias, R. D. Rosenstein, and G. A. Jeffrey, Acta Cryst., 1965, 18,E. Shefter and K. N. Trueblood, Acta Cqjst., 1965, 18, 1067.1965, 12, 60, 76.1039H . M . POWELL, (1. K. PROUT, S. C . WALLWORK 611nearly normal chair configuration. The molecular stereochemistry and theabsolute configuration have been determined 483 for the methiodide hydrate ofleurocristine, an alkaloid with anti-tumour activity, which is also known asvinicristine. Caracurine-I1 has been studied as its dimethiodide and shown 484to have the structure and relative stereochemistry (83). The cyclohexaxlerings E and E' have considerably flattened chair conformations and the piper-idine rings D and D' have the boat form.The five-membered rings are allnon-planar and the planes of the indoline ring systems are inclined to eachother a t an angle of 58". Chimonanthine has been S ~ O W I ~ ~ by X-rayanalysis of its dihydrobromide, to have the structure (a), in which ringsc and a' adopt the envelope conformation with an average internal angle of104". Rings B and B' are planar with average internal angles of 108". Themolecule is not centrosymmetric ; the two halves are rotated about the centralbond in such. a way that both benzene rings are on the same side of themolecule. Transannular cyclisation of the iminium salt of dihydrocleava-mine yields a compound with an Aspidosperm skeleton. The structure ofthe N-acetyl derivative has been e~tablished,~sB by X-ray analysis of themefhiodide, as N(a)-acetyl-7-ethyl-5-desethylaspidospermidine (85) in whichthe six-membered ring containing the nitrogen atom has a boat conformation.The absolute configuration was established by the anomalous-dispersionmethod.Further details of the structure of securinine hydrobromide dihy-drate have been The piperidine ring has a skewed-boat form and483 J. W. Moncreif and M. N. Lipscomb, J. Amer. C h . SOC., 1965, 87, 4863.4s4 A. T. McPhail and G. A. Sim, J . Chem. SOC., 1965, 1663.486 I. J. Grant, T. A. Hamor, J. M. Robertson, and G. A. Sim, J . Chem. SOC., 1965,486 A. Camerman, N. Camerman, and J. Trotter, Acta Cryst., 1966, 19, 314.487 S. Imado, M. Shiro, and Z . Rorii, Chem. and Pharm. Bull (Japan), 1965, 13,5678.643612 CR Y S TAL LO G R AP €I Ythe diene part is not planar but composed of two planes with an angle of 10"between them. The stereochemistry of phyllochrysine has been confirmed,488by an X-ray study of its methiodide, and the piperidine ring has been foundto have the boat form.Two independent crystal structure analyses 4i39 of thehydrobromide monohydrate of lunarine have established its constitution andrelative stereochemistry as (86). Much chemical and crystallographic evi-dence on the structures of tetrodotoxin and its derivatives has been reviewed,490and it is deduced that both tetrodotoxin and anhydrotetrodotoxin havezwitterionic hemilactal structures. The full account 491 has appeared of thestructure of heteratisine hydrobromide monohydrate which was describedbriefly last year.The structure of a-bromoisotutinone is found 492 to be in agreement withthat of the corresponding alcohol, a-bromoisotutin, reported last year.Itdiffers from that deduced chemically in having one lactone group and twoepoxide groups instead of being a dilactone. This underlines the need forcaution in interpreting infrared spectra of oxygen functional groups becausethe diagnostic features for epoxide groups are not well defined. The consti-tution and absolute stereochemistry (87) has been determined 493 for thesesquiterpenoid antibiotic verrucarin by an X-ray study of its p-iodoben-zenesulphonate. The stereochemistry (88) deduced for acorone, from thestructure determination of its p-brom~phenylhydrazone,~~~ differs from thatproposed earlier on chemical grounds. The unexpected axial conformationof the methyl group may not be retained in solution.The stereochemistry ofcc-santonin has been established 495 by X-ray analysis of its 2-bromo-deriva-tive as (89), in which the cyclohexadienone ring is flat but the cyclohexanering has the expected chair conformation. The 5-membered lactone ringhas an average valence angle of 105". The absolute configuration shown hasbeen derived chemically. In 2-bromodihydroisophoto-~-santonic lactoneacetate (90) the cyeloheptane ring adopts a somewhat flattened chair con-formation 496 and the other two rings are non-planar, though there is plan-arity over most of the lactone ring because of resonance with the ionicstructure -+O=C-0-.A redetermination 497 of the crystal structure oflongifolene confirms the structure derived from previous X-ray and chemicalstudies. It is an elaboration of that of bornyl chloride in that the thirdisoprene unit completes a seven-membered ring. Ophiobolin is the firstexample of a C,, terpenoid. Its structure and absolute configuration havebeen determined 498 ns (91) by X-ray analysis of its bromomethoxy-deriva-488 C. Pascard-Billy, Compt. rend., 1965, 260, 555.u9 C. Tamura, G. A. Sim, J. A. D. Jeffreys, P. Bladon, and G. Ferguson, Chem.490 K. Tsuda, S. Ikuma, M. Kawamura, R. Tachikawa, K. Sakai, C. Tamura, and4g1 M. Przybylska, Acta Cryst., 1965, 18, 536.492 M. F. Mackey and A. McL. Mathieson, Acta C:ryst., 1965, 19, 417.4esA.T. McPhail and G. A. Sim, Chem. Comm., 1965, 350.lg4C. E. McEachan, A. T. McPhail, and G. A. Sim, Chem. Comm., 1965, 276.496 J. D. M. Asher and G. A. Sim, J . Chennz. SOC., 1966, 6041.4g6 J. D. M. Asher and G. A. Sim, J . Chem. SOC., 1965, 1584.497 A. F. Cesur and D. F. Grant, Acta Cryat., 1965, 18, 55.c98 S. Nozoe, M. Morisaki, K. Tsuda, Y. Iitaka, N. Takahashi, S. Tamura, K. Ishibashi,Comm., 1965, 485.0. Amakasu, Chem. and Pharm. Bull (Japan), 1964, 12, 1357.and M. Shirasaka, J . Amer. Chem. SOC., 1965, 87, 4968H . M. POWELL, C. K . PROUT, S. C. WBLLWORK 613O W H t 6 0, )--AO W ( 9 ' )0Utive. Biogenetically, it is probably constructed from five isoprene unitslinearly linked head-to-tail. Structure determination 499 of methyl mela-leucate iodoacetate (92) confirms the constitution of melaleucic acid as3 p- hydroxy-up-20 ( 29 ) - ene -27,28 -dioic acid.Some abnormally high C-Cbond lengths are attributed partly to steric hindrance and partly to thefact that such bonds seem to be weakened when they are adjacent to anumber of sp3-sp3 bonds. The structure of the triperpene arborinol has beenestablished 500 by an X-ray study of 2a-bromoarborinone, and the chemi-cally derived structure of eupteleogenin has been confirmed by an X-raystudy 501 of its iodoacetate. Substance B from the timber Cedrela othratu isfound502 to have the structure (93) which is identical with that of mexi-canolide from Cedrela mexicanu. The position of the double bond in ring c isestablished by the planarity of this region of the molecule.Structure determination 503 of 4-bromo-9/?,10a-pregna-4,6-diene-3,20-499 S.R. Hall and E. N. M a s h , Acta Cryst., 1965, 18, 265.0. Kennsrd, L. R. di Sanseverino, H. Vorbruggen, and C . Djerassi, TetrahedronM. Nishikawa, I<. Kamiya, T. Muratct, Y. Tomiie, and I. Nitta, TetrahedronLetters, 1965, 3433.Letters, 1965, 3223.1965, 84, 885.602S. A. Adeoye and D. A. Bekoe, Chem. Comm., 1965, 301.603 C. Romers, E. van Heykoop, B. Hesper, and H. J. V. H. Geise, Rec. Trav. chirn.614 CRYSTALLO GRAPH Ydione establishes that the methyl groups at positions 18 and 19 lie above andbelow the ring-system of the molecule, respectively, in agreement with thefact that it belongs to the 9/3,10a-series. Ring c has the chair conformation,and this, together with the 9p,lOa configuration, results in a bent shape forthe molecule, in contrast with the planar ring-systems of “ normal ” chole-stane derivatives.Structure analysis 5~ of ecdysone, using the automated‘‘ collapsed-molecule ” method, shows it to be 2#?,3/3,14a,22/3F,25-penta-hydroxy-5#?-cholest-7-en-6-one. The angles in the five-membered ring areagain less than tetrahedral. The most interesting feature, in the structure 505of suprasteryl I1 4-iodo-5-nitrobenzoate, is the three-membered ring whichis cis-fused to the five-membered ring and joins the six-membered ring c at aspiro-junction. Only small movements of the atoms in the calciferol struc-ture are required to produce this structure. Ring c has the chair conforma-tion and the fusion of rings c and D is trans.The side-chain appears in thesame configuration as that found in calciferol and lumisterol.Atrovenetin, a metabolite of Penicillium atrovenetum, is found,806 byX-ray analysis of atrovenetin orange trimethyl ether ferrichloride, to havethe constitution (94). A preliminary report 507 of the structure of erythro-mycin A confirms the structure and stereochemistry already proposed onchemical grounds. In the structure of 6- (N-benzylformamido)penicillanicacid,508 the amide group is planar, as in previous X-ray structures of peni-cillins and cephalosporin. It differs from penicillin mainly in that its amideoxygen atom is on the opposite side of the molecule from the other C=Ogroups, whereas all three C=O groups, and the nitrogen atom of the thiazoli-dine ring, are on the same side of the molecule in penicillin.This may accountfor the loss of activity in penicillanic acid. A refinement of the structureof terramycin hydrochloride confirms that this structure is similar to aureo-mycin, including an abnormal amide group which appears to have thehydrogen atom of an intramolecular hydrogen bond attached to its oxygenatom. The main differences from the aureomycin structure are in ring IV,probably owing to the absence of the chlorine atom. Tetracycloxides are anew class of tetracyclines, and the structure determination 510 of two iso-morphous halogen derivatives confirms the presence of the hemiketal linkC(4)-0-C(6). Both the ring containing this link and ring R have the chair504R.Huber and W. Hoppe, Chem. Be?., 1965, 98, 2403.C. P. Saunderson, Acta Cryst., 1965, 19, 187.soGI. C. Paul and G. A. Sim, J . Chm. Soc., 1965, 1097.607 D. R. Harris, S. G. McGeschin, and H. H. Mills, Tetrahedron Letters, 1965, 679.D. J. Hunt and D. Rogers, Biochem. J., 1964, 93, 35c.5O9 H. Cid-Dresdner, 2. Krist., 1965, 121, 170.61* J. H. van den Rende, J. Amer. Chem. SOC., 1965, 87, 929H . M. POWELL, C . K . PROUT, S. C. WALLWORK 616conformation. The enolisation of ring A seems to be different in the twoderivatives. The structures include solvent of crystallisation, dimethyl-formamide, which partakes in the hydrogen-bonding. The structure ofisoquinocycline A, determined by X-ray analysis 611 of the isomorphoushydrochloride and hydrobromide, consists of five fused rings joined to apyrrolopyrrole nucleus, through a spiro atom, and also to a sugar-like moiety,through a glycosidic link.The pyrrolopyrrole nucleus is planar and has itsnitrogen atoms directed away from the aromatic nucleus, and the wholefuran-pyrrolopyrrole system is arranged trans to the sugar. Dioxan mole-cules of solvation occupy large cavities between the antibiotic moleculesand are hydrogen-bonded to the two secondary OH groups of the sugar.The mould product sporidesmin is the causative agent of facial eczema insheep. X-Ray analysis 512 of its methylene dibromide adduct has establishedits structure as (95), in which the disulphide bridge forces ring A into a boatform.One of the keto oxygen atoms of this ring is linked by an intramole-cular hydrogen bond to the hydroxyl group attached to ring B. The struc-ture and absolute configuration of duclauxin have been established in anX-ray study 513 of monobromoduclauxin.A survey51a of theresults of recent neutron and X-ray diffraction studies of crystalline hy-drates shows that linear hydrogen bonds are not as common in these com-pounds as has been hitherto assumed. Bent and bifurcated hydrogen bonds,as well as hydrogen atoms in positions which do not form hydrogen bonds,have been found to occur even in cases where arrangements with morelinear hydrogen bonds would have been geometrically possible. It seems thatthe orientation of the water molecules, and hence the geometry of the hydro-gen bonds, is determined by the electrostatic interactions between the watermolecules and the surrounding atoms.The crystal structure of 3,5-dibromo-4-aminobenzoic acid is interesting because of its hydrogen-bond scheme.515Two sets of crystallographically independent molecules form dimers byhydrogen-bonding of their carboxyl groups and the two amino groups, atthe outer ends of a dimer of one type, each form two NH-0 hydrogen bondsto two dimerised carboxylic groups of the other set of molecules. Eachhydrogen bond of a dimer is across a mirror plane, for one set of molecules,or across a two-fold axis for the other set, so that both types must be eithersymmetrical or statistically symmetrical. Since d( OH-..O) = 2.56 A, sta-tistical symmetry is more likely.This hydrogen-bonding links the moleculesinto an infinite pattern of squares which form layers with only van der Waalsforces between them. Some reports of CH.4-O hydrogen bonds have alreadybeen mentioned in earlier sections. Other examples are found in picolinicwhere a distance of 3-05 A occurs between C(3)H and O=C of a car-boxyl group of a neighbouring molecule, and in cytidine,477 where an intra-molecular contact of 3.233 and an intermolecular contact of 3.351 Amight both be weak CH-..O hydrogen bonds. Another example is found inMolecular Complexes and Molecular Interactions.511 A. Tulinksy, J . Amer. Ghem. SOC., 1964, 86, 5368.612 J. Fridrichsons amd A. McL. Mathieson, Acta Cryst., 1965, 18, 1043.613 Y.Ogihara, Y. Iitaka, and S. Shibata, Tetrahedron Letters, 1966, 1289.614 W. H. Baur, Acta CTyst., 1965, 10, 909.m A. K. Pant, Ada Cryst., 1965, 19, 440616 CRYSTALLOGRAPEYD-( +)-barium uridine-5’-phosphate where it further stabilises the anticonfiguration about the C(4)-C( 5’) bond in the side-chain. Hydrogen-bonding between OH groups and benzene rings has previously been inferredfrom infrared spectra, and it is now confirmed crystallographically in thecrystal structure determination5I6 of a cyclic peptide. There is an intra-molecular arrangement in which a benzyl group approaches an OH group ofthe same molecule as closely as possible. The perpendicular distance fromthe ring to the oxygen atom is 3.07 A and the angle between the normal tothe benzene plane and the C-0 bond is 106”, suggesting that the OH protonprobably lies on the normal to the ring.A peak representing this proton wasfound in the expected region in a difference Fourier synthesis. The O-Hbond is not directly over the centre of the ring but 0.84 A away from thisposition, presumably because of the geometrical requirements of the molecule.Although lithium and sodium oxalates crystallise from water as snhy-drous salts (contrary to the behaviour of oxalates of other alkali metals) theycrystallise from H,O, with one molecule of crystallisation. In the struc-ture,517 endless chains of alternate oxalate ions and H,O, molecules arelinked together by hydrogen bonds of length 2.588 & 0.006 A. The oxalateions are planar with d(C-C) = 1-570 & 0.011 A, and the H,02 moleculesare in the unexpected trans conformation with d ( 0 - 0 ) = 1.466 -+ 0.009 8.A distorted octahedral co-ordination of sodium ions by oxygen atoms linksthe chains together.In the crystal structure of the 2 : 1 complex of mesi-tsldehyde, C,H,(CH,),CNO, with perchloric acid, there are layers 518 inwhich hydrogen-bonded mesitaldehyde dimers and perchlorate ions occurin a 1 : 1 ratio. The layers are stacked in such a way that mesitaldehydemolecules overlap in different ways in two separate types of irregular column.In one type, the rings overlap with a perpendicular separation of 3.46 A, andin the other type an o-methyl substituent of one layer overlaps a ring in anadjacent layer. Association of the proton from the perchloric acid with thecarbonyl groups of two mesitaldehyde molecules is indicated by a peak on adifference Fourier map and also by the hydrogen-bond distance of2.46 & 0.01 between the pair of oxygen atoms.In these hydrogen bonds,the proton is more likely to be disordered than centrally placed. Threeof the four nitrogen atoms of hexamethylenetetramine in the complexCaBr,,1oH20,2(CH2),N,, are linked by N-.HO hydrogen bonds to watermolecules which form part of the octahedral hydrate co-ordination spheresof three difirent calcium ions.51g This results in hydrogen-bonded layerswhich are linked together partly by the calcium ion co-ordination and partlyby a further hydrogen bond to the fourth nitrogen atom of hexamethylene-tetramine. 2,6-Lutidine may be separated from coal-tar fractions by theformation of urea complexes.An X-ray study 520 of the 1 : 1 complexshows that lutidine molecules are attached to bands of hydrogen-bonded61sA. T. McPhail and G. A. Sim, Chern. Comn., 1965, 124.617 B. F. Pedersen and B. Pedersen, Actu Chem. Scund., 1964, 18, 1454.618C. D. Fisher, L. H. Jensen, and W. M. Schubert, J. Anzer. Chem. SOC., 1965,519 P. De Santis, A. L. Kovam, A. M. Liquori, and L. Mazzarella, J. Amer. C h m .620 J. D. Lee and S . C. Wallwork, Acta Cryst., 1965, 19, 311.87, 33.SOC., 1965, 87, 4965H. M. POWELL, C . K . PROUT, S . C . WALLWORK 61 7urea molecules by NH.-N hydrogen bonds of length 3.24 A, the planes of thelutidine and urea molecules being a t right angles to each other.The inter-leaving of lutidine molecules attached to adjacent bands also contributes tothe stability of the structure, but it is not clear why only this base in thecoal-tar fraction forms such complexes. As a contribution to the study ofurea a,s a protein denaturant, the structure has been determined521 of the1 : 1 complex that L-cysteine ethyl ester hydrochloride forms with urea.The structure can be described as alternating layers of chloride ions andhydrogen-bonded urea-cysteine ethyl ester complexes. It is interesting that,besides urea-urea hydrogen-bonding, each urea molecule is linked by a pairof hydrogen bonds to a cysteine ethyl ester molecule, from NH, of urea to0s of the cysteine ring and from the protonated NH,+ of cysteine to 0 s ofurea.9-Ethyladenine and l-methyl-bromouracil form a 1 : 1 complex inwhich the two molecules occur as a nearly-planar hydrogen- bonded pair 522connected by an NH-N hydrogen bond from N(3) of uracil to the adenineimidazole N(7) and by an NH...O hydrogen bond from NH, of adenine to0(2)=C(2) of uracil. Additional hydrogen bonds from the amino group toO(4) of ura