ISSN:0069-3022    

DOI:10.1039/GR97269FX001

出版商:RSC    

年代:1972

数据来源: RSC

ISSN:0069-3022    

DOI:10.1039/GR97269BX003

出版商:RSC    

年代:1972

数据来源: RSC

摘要:

2 Reactions of Atoms and Small Molecules By R. J. DONOVAN Department of Chemistry University of Edinburgh West Mains Road Edinburgh EH9 3JJ and D. HUSAIN and L. J. KIRSCH Department of Physical Chemistry University of Cambridge Lensfield Road, Cambridge CB2 7EP 1 Introduction Since the publication of the last Annual Report on this topic,’ which reviewed the kinetic study of atoms and small molecules by spectroscopic methods for the period 1966-1971 there has been a relatively large output of literature in this field. Also a number of very useful review articles on elementary processes, particularly relevant to the present Report have appeared. This Report will deal with the literature for 1971-1972 with the main emphasis on work em-ploying direct spectroscopic methods for monitoring kinetic species of interest.Of the recent review articles that of Troe and Wagner’ deals with a wide area of chemical kinetics and includes detailed coverage of dissociation and recom-bination reactions molecular beam studies (including ion-molecule collisions), unimolecular reactions and the thermal study of bimolecular reactions. Aspects of theory relevant to these areas are included in the article. An impressive set of review articles concerned with most modern aspects of chemical kinetics has been prepared under the editorship of P ~ l a n y i . ~ This book contains ten chapters and includes the consideration of atomic and bimolecular reactions chemi-luminescent reactions molecular beam reactions ion-molecule reactions and energy-transfer processes.A detailed review on the use of electron paramagnetic resonance for the quantitative determination of atomic and radical concentrations has been given by We~tenberg,~ and includes a bibliography of kinetic studies employing this technique. An article which is particularly useful for a consideration of processes involving metastable noble-gas atoms (not dealt with in the present Report) is that of R. J. Donovan and D. Husain Ann. Reports ( A ) 1971 68 124. ’ J . Troe and H. Gg. Wagner Ann. Rev. Phys. Chem. 1972 23 3 1 1. ‘MTP. International Review of Science Physical Chemistry Series 1 ’ Vol. 9 ‘Chemical Kinetics’ ed. J. C. Polanyi Butterworths London 1972. A. A. Westenberg Progr. Reaction Kinetics 1972 7 23. 1 20 R. J . Donovan D. Husain and L. J.Kirsch Rundel and Stebbings.’ The study of energy transfer from states pumped by laser transitions has been reviewed in a wide-ranging article on ‘Lasers in Chemistry’ by Moore.6 A detailed and critical review of the addition reactions of atoms and radicals with alkenes alkynes and aromatic molecules has been given by Kerr and Parsonage.’ This contains extensive tables of ‘preferred values’ of rate constants. Rate data for many of the reactions involving sulphur-containing radicals and molecules (including atomic sulphur) have been reviewed by Cullis and Mulcahy.8 A collection of papers highly representative of much present work on the reactions of atoms and molecules in excited states is that resulting from the recent Faraday Discussion on this ~ubject.~ Many of the investigations reported were concerned with direct spectroscopic methods for monitoring transient species in kinetic processes.A number of extensive compilations of kinetic data for elementary processes have also been published recently. The first volume in a series ‘Evaluated Kinetic Data for High Temperature Reactions’ based on the Leeds University reports on ‘High Temperature Reaction Rate Data’ and dealing with reactions in H2-0 systems has appeared.” The material from the original reports has been revised and updated. A compilation concerned with reviews of kinetic data, that have already been published and also those in preparation has also appeared recently.’ A survey of the kinetics of bimolecular and termolecular reactions up to the end of 1969 has been given by Kondratiev.” A bibliography on chemical kinetics in C-0-S and H-N-0-S systems listing published papers and reports on the gas-phase reactions of species containing C-0-S and H-N-O-S and complete up to June 1971 has also appeared.13 2 Monatomic Species Hydrogen.-The highly sensitive method of monitoring hydrogen atoms by means of the Lyman a transition (H22P1,,,3,2-12S1,2 ; 1 = 121.6 nm) either by absorp-tion attenuation or resonance fluorescence following the production of ground-state hydrogen atoms continues to be employed.Ahumada Michael and R. D. Rundel and R. F. Stebbings in ‘Case Studies in Atomic Collision Physics’ ed. E. W. McDaniel and M. R. C. McDowell North Holland Amsterdam 1972 v01.2. C. B. Moore Ann. Rev. Phys. Chem. 1971 22 387.’ J. A. Kerr and M. J. Parsonage ‘Evaluated Kinetic Data and Gas Phase Addition Reactions. Reactions of Atoms and Radicals with Alkenes Alkynes and Aromatic Compounds’ Butterworth London 1972. C. F. Cullis and M. F. R. Mulcahy Combustibn and Flame 1972 18 225. Papers in Faraday Discuss. Chem. Soc. 1972 no. 53. l o ‘Evaluated Kinetic Data for High Temperature Reactions’ Vol. 1 ‘Homogeneous Gas Phase Reactions of the H,-02 System’ by D. L. Baulch D. D. Drysdale D. G. Horne, and A. C. Lloyd Butterworth London 1972. CODATA Bulletin No. 3 ICSU CODATA Central Office 6 FrankfurtiMain Germany, 1971. V. N. Kondratiev ‘Rate Constants of Gas Phase Reactions Reference Book’ (trans-lated from the Russian) ed. R. M. Friston National Technical Information Service, Springfield Va.22151 U.S.A. (COM-72-10014). 1972. l 3 Nat. Bur. Stand. Special Publication 362 ‘Chemical Kinetics in the C-0-S and H-N-0-S Systems’ by F. Westley U.S. Government Printing Office Washington D.C., 20402 U.S.A. 1972. Reactions of Atoms and Small Molecules 21 O ~ b o r n e ' ~ have made an extensive study of the recombination of hydrogen atoms with 0 ,NO and CO. The atoms were generated by the transient mercury-photosensitized decomposition of molecular hydrogen and monitored in absorption by means of the Lyman a transition. These authors report the rate data shown in Table 1. Where a comparison can be made the data for re-Table 1 Rate constants (k) for hydrogen-atom-molecule recombination studied by absorption of Lyman a-radiation (room temperature) H + O + M - + H 0 2 + M M 1032k/~m6 molecule-' s-l H2 Kr He Ar Ne 1.2 * 0.1 1.1 & 0.1 0.75 f 0.33 0.60 & 0.04 0.15 & 0.03 H + N O + M + H N O + M M 1032k/~m6 molecule-2 s - l H2 Kr He Ar Ne 6.3 f 0.3 5.4 f 0.3 4.3 * 0.1 3.9 f 0.1 2.1 * 0.1 H + C O + M -+ HCO+M M 1032k/~m6 s - l H2 Kr Ar He Ne 0.8 & 0.04 0.69 f 0.03 0.62 0.07 0.60 +_ 0.07 0.48 f 0.05 combination with 0 and NO differ from those of Dorfmann and Bishop,' who employed pulsed radiolysis by about a factor of three.The data of Ahumada et a1.14 are however one to two orders of magnitude greater for recombination with CO. These authors14 suggest that energy transfer and intermediate complex mechanisms may be operative for H + NO and H + O2 with heavy monatomic third bodies.Kurylo' has employed Lyman ct resonance fluorescence following flash photolysis in order to investigate the temperature dependence of the reaction rate of H + O2 + M and has found that in the temperature range 2 0 3 4 0 4 K, 1.99 & 0.38 kJ mol-RT k, = 6.66( + 1.2 - 1) x exp ( l 4 J . J. Ahumada J . V. Michael and D. T. Osborne J . Chem. Phys. 1972 57. 3726. I s W. P. Bishop and L. Dorfmann J . Chem. Phys. 1970,52 3210. M. J . Kurylo J . Phys. Chem. 1972. 76 3518. 1 22 R. J. Donovan D. Husain and L. J. Kirsch Relative efficiencies for the deactivation of the upper state (22P1/2,3/2) are also reported namely, CH N He Ar = 15.7 3.4 1.0 1.0 at 298 K, N He = 4.5 1.0 at 226 K. The same technique has been employed by Welge et al.' ' to study the reaction of H + CH,O for which the rate constant k(297 K) = 5.4 _+ 0.5 x cm3 molecule- ' s- is found.The cross-section for Lyman a emission on the collision of H+ and H in the 1-25 keV energy range with CO and CO, and CH and NH, are reported by Birely and McNeal.18 These authors report qualitative results for the production efficiencies of H(2,P) and H(2,S) from H+ and H as a function of kinetic energy. Westenberg and de Haas" have also studied H atoms directly and also OH and 0 by e.p.r. in a flow system following which they report relative rate con-stants for the reactions of H and HO : H + HO -% H + 0 (2) H + H O * O H + O H (3) H + HO 5 H 2 0 + 0 H + 0 + M -% HO + M(M = Heor Ar) (4) k k k = 0.62 0.27 0.1 1.The rate of the reaction (1) is also measured yielding k = 1.9 cm' molecule-2 s- ' in good agreement with the recent work of Kurylo'' and the early work of Clyne and Thrush" (2.2 x Wagner and his co-workers have also employed e.p.r. spectroscopy for the measurement of hydrogen-atom concentrations as well as using mass spectro-metric and gas chromatographic analysis for product measurement. This work has recently resulted in the characterization of a number of rate processes for the hydrogen atom namely, 0.3 x cm6 molecule-' s-'). H ,C-C=CH,* kY H + H3C-C-CH kb H,C-CH=CH2* -8.4 f 0.8 kJ mol-' RT k = 1.1 0.02 x lo-l'exp ( ) cm3 molecule- 1 s- 1,'' *' B. A. Ridley J. A. Davenport L. J. Stief and K. H. Welge J . Chem. Phys. 1972 57, l 6 J.H. Birley and R. J. McNeal J . Chem. Phys. 1972,56 2189. l 9 A. A. Westenberg and N. de Haas J . Phys. Chem. 1972,76 1586. 2 o M. A. A. Clyne and B. A. Thrush Proc. Roy. SOC. 1963 A275 559. 2 1 H. Gg. Wagner and R. Zellner Ber. Bunsengesellschaft phys. Chem. 1972,76 518. 520 Reactions of Atoms and Small Molecules 23 H3C-C=CH2* (7) k9 k h 4 H + H,C=C=CH, cm3 molecule- s- ',, [ -8.4 f ";("T" mol-' k = 1.4 f 0.3 x lo-" exp cm3 molecule- ' s- 1,22 1 - 11.3 rf 1.7 kJ mol- ' k = 7 rf 3 x 10-12exp iso-C,H * (9) kP H + H3C-CH=CH2 k b n-C3H,* (10) k = 9.0 1.0 x 10-12exp cm3 molecule- s- 1,23 ( - 5.2 rf yTkJ mol-cm3 molecule- ' s- 1,23 1 - 11.5 rf 0.4 kJ mol- k = 7.3 rf 1.0 x 10- l 2 exp H + N2H3 2NH2 (12) cm3 molecule- s- 1,24 ( - 10.4~Tmo1- ' k = 2.2 x lO-"exp and k, = 2.7 x lo-" (3111 molecule-' s-1.24 Various methods of mass spectrometric analysis in some cases coupled with other analytical techniques have been employed to determine rate data for hydrogen-atom reactions.Teng and J ~ n e s ~ ' ~ ~ ~ have characterized rate constants for the reactions of H atoms with ethylene vinyl fluoride 1,l-difluoroethylene 2 2 H. Gg. Wagner and R. Zellner Ber. Bunsengesellschaff phys. Chem. 1972 76 667. 23 H. Gg. Wagner and R. Zellner Ber. Bunsengesellschaft phys. Chem. 1972,76,440. 2 4 M . Gehring K. Hoyermann H. Gg. Wagner and J. Woifrum Ber. Bunsengesellschafr " L. Teng and W. E. Jones J.C.S. Faraday I 1972,68 1267. '' L. Teng and W. E. Jones J.C.S. Faraday I 1972,68 189. phys. Chem. 1971,75 1287 24 R. J . Donovan D.Husain and L. J . Kirsch and various resulting intermediates. Rommel and Schiff2 have measured the reaction rates of H atoms in a flow system with H,S and COS and report kHzS = 3.8 x and k,, = 2.2 x 10-14cm3 molecule-'s-'. A fast flow system has been employed by Phillips et to investigate the process H + ICN -% HCN + I (13) These authors report k 1 3 = 3.2 k 1.0 x cm3 molecule-'s-' (296 K). has employed mass spectrometric analysis to measure the relative rates of isotopic exchange arising from the reactions of H with DCI. Studies of translationally energized H atoms by product analysis include the measurements on deuterium-atom abstraction from various ethanes and silanes by Hong and Mains,30 who found reaction with the silicon compounds more rapid than with the carbon analogues.A classical photochemical study of H atom abstraction from silanes by normal D atoms following the photolysis of C2D4 at 2 = 202.2 nm has been reported by Gunning et ~ l . ~ who measured absolute rate data. The reaction of 'hot' H atoms generated by flash photolysis of HI with COS has been reported by Oldershaw and Porter,32 who found that the probability of S atom abstraction was reduced by moderating collisions. Fink and Nicholas33 have measured the energy threshold (36 rf 3 kJ mol- l) for the reaction of translationally energized D atoms with cyclohexane. Some relative rates of the reaction of 'hot' H atoms with CO and N,O following the flash photolysis of HI are described by Tomalesky and S t ~ r m . ~ ~ Other kinetic investigations of hydrogen atoms include a cross-beam study of D + H by Krause et who report k(1400 K) = 1.2 & 0.6 x lo-'' cm3 molecule-'s-'.Gann and D ~ b r i n ~ ~ have computed the average value for the reaction cross-section of H + HBr .+ H + Br over the collision-energy range 0.35-1.7 eV from previous atom-recoil data37 and find Q = 1.6 & 0.3 A*. S ~ h o f i e l d ~ ~ has estimated the rate constant for the reaction H + O,(a'A,) -!% OH + 0 (14) from the analysis of atmospheric observations of O,(a'A,) current atmospheric models and established experimental rate constants and reports k < 3 x 10- cm3 molecule- s- '. This must be considered a crude estimate as k14 5 6.5 x 10- cm3 molecule- s- 1.39 Finally we mention the investigations 2 7 H. Rommel and H. I .Schiff Internat. J . Chem. Kinetics 1972 4 547. G . P. Horgan M. R. Dunn C. G. Freeman and L. F. Phillips J . Phys. Chem. 1972, 76 1392. 2 9 G. 0. Wood J . Chem. Phys. 1972 56 1723. 30 Kong-yi Hong and G. J. Mains J . Phys. Chem. 1972 76 3337. 3 1 3 2 G. A. Oldershaw and G. Porter J.C.S. Faraday I 1972,68,709. 3 3 R. D. Fink and J. E. Nicholas J.C.S. Faraday I 1972 68 1706. 3 4 R. E. Tomalesky and J. E. Sturm J.C.S. Faraduy IZ 1972 68 1241. 3 5 J. Geddes H. F. Krause and W. L. Fite J . Chem. Phys. 1972 56 3298. 36 R. G. Gann and J. Dubrin J . Phys. Chem. 1972,76 1321. 3 7 3 8 39 R. L. Brown J . Geophys. Res. 1970 75 3935. K . Obi H. S. Sandhu H. E. Gunning and 0. P. Strausz J . Phys. Chem. 1972 76,391 1. R. G. Gann W. M. Ollison and J. Dubrin J . Chem.Phys. 1971 54 2304. K. Schofield Internat. J . Chem. Kinetics 1972 4 255 Reactions of Atoms and Small Molecules 25 by Falconer and S ~ n d e r ~ ' ~ ' on the effect of deuterium substitution on the reaction of H(D) atoms with propene. These authors report the effects on relative rates of atom abstraction addition and disproportionation-recombina-tion ratios for deuteriated propyl radicals. Sodium and Potassium.-The emphasis of kinetic investigations on Group I atoms over the past year has been concerned with the excited state of sodium, (3,PJ). Krause Fricke and White4 have carried out a set of particularly detailed experiments on the observation of sodium D-line emission (3,PJ -+ 3,S1,,) following excitation of sodium atoms by internally excited H, D, or N in crossed molecular beams.As a result they report excitation cross-sections for N as a function of the vibrational level u and Av the most probable transition (Table 2). The alternative values presented in Table 2 arise from the use of a Table 2 Cross-sections (a) for the excitation of Na(3,Sl,,) -+ Na(32PJ) by vibrutionally excited molecular nitrogen Most probable transitions Av q>,,./A2 11-3 10-3 8-2 6- 1 4-0 271 190 3001640 751290 2011 70 13/78 particular chosen form for the kinetic energy dependence of the excitation cross-~ection.~~ Krause et compare their results with the ionic curve-crossing theory of Bauer et for the quenching of Na(3,PJ) by N, by invoking the principle of detailed balancing. The excitation of sodium by vibrationally excited N in a flow system has been studied by Sadowski Schiff and who found CT = 100 A' for the transition in closest resonance (1 1-3).This may be compared with the result of Krause et uL4 (Table 2) for this process. The collisional quenching of Na(3,P) by N and H,O over the temperature range 1500-2500 K has been studied by Linse and E l ~ e n a a r ~ ~ who employed atomic resonance fluorescence of the sodium d i n e s in a flame. The quenching cross-sections (0) for both gases were found to be independent of temperature over this range and given by 4 0 W. E. Falconer and W. A. Sunder Internat. J . Chem. Kinetics 1972 4 307. 4 ' W. E. Falconer and W. A. Sunder Internat. J . Chem. Kinetics 1972 4 315. 4 2 H. F. Krause J. Fricke and W. L. Fite J . Chem.Phys. 1972 56 4593. 4 3 E. Bauer E. R. Fisher and F. R. Gilmore J . Chem. Phys. 1969 51,4173. 4 4 C. M. Sadowski H. I . Schiff and G. K. Chow J . Photochem. 1972 1 23. P. L. Lime and R. J. Elsenaar J . Quant. Spectroscopy Radiative Transfer 1972 12, 1115. 4 26 R. J . Donovan D. Husain and L. J. Kirsch However the cross-section for N was also found to be ca. one half that at 400 K, derived from bulb experiments. This was attributed to either a strong dependence of the cross-section on velocity a t low velocity or differing cross-sections for different vibrational levels (see Table 2). Earl et have investigated the collisional quenching cross-section for Na(3,P) by various gases at different distributions of laboratory speeds for the sodium atom. This was achieved by the photodissociation of NaI in the wavelength range 190-250 nm with analysis of the d i n e emission in the presence of the added gases.Over the range 1.0-2.5 km s-’ the quenching cross-section (a) was found to vary as g-,’” where g = the relative collisional velocity and s is in the range 4-6. For a fixed value of g cr was found to vary as I > SO > C6H > CH3CN > CF3C1 > C2H4 > By reference to the experiments of Linse and EIsenaar,4’ Linse4’ has obtained an improved correlation between experiment for the quenching of Na(3,P’) by N and theory involving an ionic curve-crossing mode1.43,48,49 This was achieved by the inclusion of an attractive part in the interaction potential on collision. On the basis of this model Fisher and Smith49 conclude that cr is insensitive to the vibrational level in N and that the effect of N2(v) cannot account for the variation in the quenching cross-sections of alkali-metal atoms at low and high temperature.There would therefore appear to be some invariance between this conclusion49 and the results of Krause et aL4 (Table 2). Fontijn et al.” describe preliminary data for the reaction of Na + 0 + M, studied by atomic line absorption in a flow reactor at 1200K and report k x loh3 cm6 molecule-2 s - ’ for this three-body process. Bernstein and c o - w o r k e r ~ ~ ~ * ’ ~ have carried out a crossed molecular-beam study of K + CH31 over a range of collision energy. It was found that the total cross-section is ca. 50 A2 peaking at a collision energy of 0.18 eV. Ross et ~ 1 .’ ~ have reported on the effect of internal and translational energy on the nature of the collision of potas-sium atoms with SF, Ccl, and SnC1 in a crossed molecular-beam study. Calcium Strontium Barium and Thallium.-By contrast with previous years, there have been a number of kinetic investigations on Group 11 atoms especially barium. Particularly impressive are the beam experiments of Zare and his co-worker~.’~~’’ Zare et aLS4 have studied the electronic chemiluminescence from metal oxides in crossed molecular-beam studies of Ba Sr or Ca with N,O or NO in an attempt to ‘marry the techniques of molecular beams and molecular ~pectroscopy’.~~ These workers report metal oxide excitation cross-sections for CO,. 46 B. L. Earl R. R. Herm S.-M. Lin and C. A. Munns J .Chem. Phys. 1972,56 867. 4 7 P. L. Linse Chem. Phys. Letters 1973 18 73. 4 8 E. R. Fisher and G. K. Smith Appl. Optics 1971 10 1803. 4q E. R. Fisher and G. K. Smith Chem. Phys. Letters 1972 13 448. A. Fontijn S. C. Kurzius J. J. Houghton and J. A. Emerson Rev. Sci. Instr. 1972, 43 726. ’’ M. E. Gersch and R. B. Bernstein J . Chem. Phys. 1972,56 6131. 5 2 A. M. Rubis and R. B. Bernstein J . Chem. Phys. 1972,57 5497. 5 3 T. M. Ross S. Y. Young and J. Ross J . Chem. Phys. 1972,57 2745. 5 4 C. D. Jonah R. N. Zare and Ch. Ottinger J . Chem. Phys. 1972 56 263 Reactions of Atoms and Small Molecules Table 3 Metal oxide electronic excitation cross-sections (a) for collisions of Group II atoms 27 Collision OrdeP CIA2 aca,cIA2 Ba + N,O 1 27 Ba + NO 1 165 150 Sr + N,O 1 < 27 Ca + N,O 1 16 Ca + NO 2 93 70 Kinetic order in added gas pressure (first order in metal atom concentration).Calculated cross-sections employing an ‘electron jump’ model. Sr + NO 2 127 100 the atomic collision processes (Table 3). Schultz Cruse and %ress were also the first workers to employ laser-induced fluorescence for the observation of product u,J levels in a molecular-beam experiment. This method was applied to the study of the reaction Ba + 0 -+ BaO + 0. The fluorescence from BaO was excited by means of a tunable dye laser. The initial vibrational distribution in BaO was found to be Boltzmann in type and corresponded to a vibrational temperature of cu. 2500K. The results suggest the formation of a collision complex.” Lin et ul.s69s7 have reported beam studies of the reaction dynamics of Ca Sr or Ba with HI and Mg Ca Sr or Ba with Cl or Br,.Obenauf Hsu and Palmer5* have studied the reaction of Ba + 0 by observa-tion of the BaO emission from a diffusion flame. They propose a mechanism for electronic excitation of BaO via a BaO complex. These workers have further studied the process Ba(g) + N,O or NO -% BaO(A ‘C or X ‘C) + N or NO by measurement of the A ‘C-X ‘C emi~sion.~’ The photon yield for N,O was found to be 0.0039 and that for NO was 0.00033. This latter value for NO is consistent with previous data of Ottinger and which leads to the con-clusion that the major route on reaction is to the ground state of BaO. Using Zare’s data,60 Palmer et a1.” were able to place limits on the cross-sections for reaction (ure) to the BaO(A ‘C) state namely for N20,ure < 6-7A2 and for Naumann and Miche16’ have measured relaxation times for electronic excita-tion of barium and thallium atoms behind reflected shocks using atomic line absorption spectroscopy.From this they have obtained quenching cross-sections which were not found to be noticeably dependent on temperature (15) NO,,a, < 2-381,. 5 5 A. Schultz H. W. Cruse and R. N . Zare J . Chem. Phys. 1972,57 1354. ” C. A. Munns S.-M. Lin and R. R. Herm J . Chem. Phys. 1972,57 3099. 5 7 S.-M. Lin C. A. Munns and R. R. Herm J . Chem. Phys. 1972,58 327. 5 8 R. H. Obenauf C. J. Hsu and H. B. Palmer Chem. Phys. Letters 1972 17 455. 5 9 R. H. Obenauf C. J. Hsu and H. B. Palmer J . Chem. Phys. 1972 57 5607; 1973, 58 2674.‘O Ch. Ottinger and R. N. Zare Chem. Phys. Letters 1970,5 243. 6 ’ F. Naumann and K. W. Michel 2. Physik 1972,255 3480 28 R. J. Donovan D. Husain and L. J. Kirsch Table 4 Quenching cross-sections (G) for barium and thallium atoms Collision IS/@ Ba(6ID2) + Ar 0.12 T1(62P3,2) + Ar 4 10-3 Ba(63D,) + Ar 0.09 5 (Table 4). Using a Landau-Zener approach these authors concluded that the pseudo-crossing for the Ba-Ar collision takes place within 0.25 eV of the D levels of barium; further that spin-orbit coupling is not rate-controlling in the quenching of BzI(~~D,) to Ba(6'So). For Ba(6'D2) the collision deactivation constants for Ar and He were found to be in the ratio of ca. 3 and it was therefore suggested that polarizability may be important in the quenching process.The self-quenching of Tl(62P3,2) by Tl(62P1,,) was found to be characterized by a collision cross-section of 5 A2.61 Linse et a1.62 have studied the collisional quenching of electronically excited strontium atoms Sr(5'P1) in a flame using resonance fluorescence (51P,-51s0, ;1 = 460.7 nm). They present deactivation cross-sections which constitute the first reported kinetic data for this state (Table 5). Table 5 Collision quenching cross-sections (a) for Sr(5'P1) Collision partner I S p 21 * 2 67 6 22 * 5 400 80 Mercury Cadmium and Iron.-Extensive work continues to be carried out on the 63P state of the mercury atom especially the 3P0 and 3P1 levels. Particularly interesting is the experimental development of kinetic studies of H S ( ~ ~ P ~ ) , characterized by an emission lifetime of ca.lo3 greater than that of Hg(63Pl) + Hg(6'So) at 253.7 nm.63 The basis of the method is a crossed molecular-beam technique in which Hg(63P2) generated by electron bombardment undergoes spin-orbit quenching to the 63P state, Hg(63P2) + M -% Hg(63P1) + M (16) followed by measurement of the strong emission at 253.7 nm. This method was first described by Martin et who reported a number of relative quenching cross-sections for various gases. These authors have recently extended this work in considerable detail65 and report the relative cross-sections given in Table 6. " T. J. Hollander P. L. Linse L. P. L. Franken B. J. Jansen and P. J. Th. Zeegers J . b 3 P. Baltayan and J. Pebay-Peyroula Compt. rend.1965 260 6569. 64 L. J. Doemeny F. J. Van Itallie and R. M. Martin Chem. Phys. Letters 1969 4 302. 6 5 F. J. Van Itallie L. J. Doemeny and R. M. Martin J . Chem. Phys. 1972 56 3689. Quant. Spectroscopy Radiative Transfer 1972 12 1067 Reactions of Atoms and Small Molecules 29 Table 6 Relative collisional deactivation cross-sections (a) for intramultiplet quenching of Hg(63P2) -+ Hg(63P,) C*H, C2D6 C2H4 cis-2-C4H, n-C4H 10 n-C4D 10 C6H6 CyClO-C6H1, CYCIO-C,D~~ ‘ZLF6 He Xe HD H2 D2 C,,l 1.00 0.72 0.65 0.045 0.23 0.21 < 0.006 0.065 0.020 0.79 0.63 0.26 (0.22) (0.18) (0.08) 0.052 0.24 0.31 0.021 0.23 0.23 0.014 < 0.005 < 0.003 0.504 0.268 0.143 These data are compared with existing data for total and intramultiplet quenching of Hg(63P1).The results for the process Hg(63P2 + indicate (a) internal degrees of freedom are required when the quenching molecule lacks excited states below Hg(63P2); (b) energy resonance is not a major factor ; and (c) the large differences in cross-sections observed with some molecules can be accounted for in terms of competitive processes such as the observation of small intramultiplet quenching by chemically reactive species. Similar experiments were later reported by Krause et who employed velocity selection and whose results are compared with those of Martin et ~ l . ~ ~ where the relative cross-sections are normalized to unity for nitrogen (Table 7). These authors66 observed some indication of struc-ture in the curves for the velocity dependence of o for H and N .Quantum yield data for intramultiplet quenching Hg(63P -.o) is presented in a detailed kinetic spectroscopic investigation by Callear and McGurk6’ on all levels of Hg(63P0,,,,). By employing a quantum yield of unity for N2,68 these 6 6 H. F. Krause S. Datz and S. G. Johnson J . Chem. Phys. 1973 58 367. 67 A. B. Callear and J. C. McGurk J.C.S. Furuduy ZZ 1973 69 97. 68 A. B. Callear and R. E. M. Hedges Trans. Furuduy Soc. 1970 66 605 30 R. J . Donovan D. Husain and L. J. Kirsch Table 7 Comparison of velocity-selected and velocity-averaged relative collisional cross-sections (a) for Hg(63 Pz ~ 1) intramultiplet quenching a(0.050 eV velocity CT (velocity Quenching gas selected)66 ~veraged)~’ N2 1.00 1 .oo NO 0.92 0.90 CH4 0.78 0.87 D2 0.18 0.20 H2 0.58 0.70 authors report quantum yields for the process 63P -ro relative to the total relaxa-tion of Hg(63P,).These results are in good agreement with those of LeRoy et a1.,69 who employed a method based on product analysis of the mercury-photo-sensitized decomposition of ethylene which is enhanced by the long-lived state Hg(63P0) (Table 8). Total cross-sections for the quenching of Hg(63P,) by isotopic Table 8 Quantum yields (0) for intramultiplet quenching Hg(63P +,) relative to total quenching for Hg(63P1) 0 (Callear and Quenching gas McGurk6’) 0 (LeRoy et ~ 1 . ~ ~ ) NO < 0.10 co 0.90 0.88 & 0.07 < 0.03 --H2 0 2 co2 N2O NH3 ND3 H2O D2O CH4 0.10 - - 0.02 < 0.0 1 < 0.10 -0.64 1.05 0.05 - 1.00 f 0.08 0.76 f 0.18 0.50 - 1.06 & 0.26 0.11 -C2H6 0.67 0.64 f 0.16 0.21 0.14 & 0.01 - 0.47 f 0.10 - 0.51 f 0.07 - 0.05 & 0.01 iso-C4H CYC~O-C~H - 0.56 f 0.10 - 0.58 f 0.02 C3H6 C3D6 2,2-C3H6D2 n-C4H 10 0 .1 1 ~ ~ 0.11 f 0.01 -C(CH3)4 C2H4 <0.10 (H and D) aromatic molecules containing a single benzene ring have been reported by Mains and Tra~htrnan,~’ who employed a modified Stern-Volmer type of experiment. The resulting cross-sections all lay in the range 48-74A ’. 69 A. Vikis G. Torrie and D. L. LeRoy Canad. J . Chem. 1972 50 176. ‘ O G. J. Mains and M. Trachtman J . Phys. Chem. 1972,76 2665 Reactions of Atoms and Small Molecules Cross-sections for the production of Hg(63P) following energy transfer from metastable diatomic molecules have been reported.Van Itallie and Martin7' have studied the velocity dependence of the process 31 C0(a3ll) + Hg(6'So) A CO(X 'C+) + Hg(63P1) (17) by time-of-flight sensitized fluorescence in a molecular beam. CO(a311) was generated by electron bombardment and the time-of-flight distribution of CO and the Hg 253.7 nm emission were measured. It was found that c1 depended on velocity (u) in the form 017 K u - ~ * * * ~ . ' over the range u = 300-700 m s-'. Thrush and Wild72 have measured the rate constant for the excitation of Hg(6,PO) in active nitrogen from the process N,(A ,C,+) + Hg(6'So) J-% N,(X 'C,') + Hg(6,Po) (18) and report k18 = 3.4 _+ 1.0 x lo-'' cm3 molecule-'s-'. This is in good agreement with the kinetic spectroscopic measurement of this rate process reported by Callear and Wood7 of k = 2.9 & 0.15 x lo-'' cm3 molecule-' S-'.Callear and his c o - ~ o r k e r s ~ ~ ~ have further reported measurements on the lifetimes and stabilities of complexes following the attachment of NH molecules to Hg(6,PO). This was carried out by photoelectric measurement of the lumines-cence from such complexes in the range ca. 260-500nm following pulsed, monochromatic excitation (A = 253.7 nm) of Hg-NH mixtures up to pressures of 10atm.75 They report complexes of formula Hg(NH3),* [from Hg(6,PO) + NH,] where n = 1 4 . 7 5 These authors also report emission lifetimes for Hg(NH3)* and Hg(ND,)* of ca. 1.8 ps,75 in excellent agreement with previous results from the luminescence phase-lag measurements of Phillips et ~ 1 .~ ~ 9 ' Callear et ~ 1 . ~ ~ have further characterized (Table 9) the dissociation constants, K, for the reaction Hg(NH3),* 5 Hg(NH,):- + NH, Table 9 Dissociation constants K for Hg(NH3)n* (n -+ n - 1) Species KJmoIecule cm -Hg(NH3)2* Hg(NH,),* 5.05 0.70 x l O I 9 Hg"H3)4* 9.1 1.8 x 10'' 6.2 & 0.60 x 10" Hg(NH3)5* z 2 . 2 x lozo 7 ' F. J. Itallie and R. M. Martin Chem. Phys. Letters 1972 17 447. '' B. A. Thrush and A. M. Wild J.C.S. Faraday I I 1972 68 2023. '' A. B. Callear and P. M. Wood Trans. Faraday SOC. 1971 67. 272. '' J. Koskikallio A. B. Callear and J. H. Connor Chem. Phys. Letters 1971 8,467. 'Is A. B. Callear and J. H. Connor Chem. Phys. Letters 1972 13 245. C. G. Freeman M. J. McEwan R. F. C.Claridge and L. F. Phillips Chem. Phys. Letters 1970 5 5 5 5 . 7 7 R. H. Newman C. G. Freeman M. J. McEwan R. F. C. Claridge and L. F. Phillips, Trans. Faraday SOC. 1970,66 2827. 7 32 R. J . Donovan D. Husain and L. J . Kirsch Direct measurements on HgH(D) following abstraction from a hydrogen-containing molecule by Hg(63P1) have been continued. Callear and Hedges7' originally employed microwave pulsed excitation to generate the electronically excited mercury atoms. Callear and M ~ G u r k ~ ~ have now used monochromatic resonance flash excitation at 1 = 253.7 nm coupled with spectrographic detection of the electronic absorption spectrum of HgH(D) to measure the yield of this molecule. The results are given in Table 10. These yields are seen to be in sensible Table 10 Absolute yields of HgH(D) from the reaction of Hg(63Pl,o) with H, D, or HD Light's Yield' theorys0,* 0.67 5 0.04 0.76 0.05 0.13 k 0.02 0.70 & 0.19 1.00 k 0.08 0.88 0.08 0.175 _+ 0.02 0.82 f 0.08 0.52 0.60 0.17 0.43 0.62 0.75 0.17 0.47 To yield HgH.To yield HgD. agreement with Light's theory,80*81 in which it is assumed that a strongly coupled complex is formed initially which fragments distributing the energy statistically amongst the products. Callear and Wood' have photoelectrically monitored the molecule HNO following the mercury flash-sensitized decomposition of H,-NO and H,-NO-C,H mixtures. They report that for the pair of reactions Hg(6'S0) + 2H HgH + H (20) k20/(k,9 + k20) = 0.67 0.04 and that this ratio is 0.76 i- 0.05 for D,.Further, the quantum yield for the decomposition of H by Hg(63P,) is found to be 0.93 0.10. Vikis and LeRoyB3 have monitored the HgH-sensitized emission following the mercury-photosensitized decomposition of hydrogen-containing molecules. '' A. B. Callear and R. E. M. Hedges Trans. Faraday SOC. 1970,66 615. 7 9 A. B. Callear and J. C. McGurk J.C.S. Faraday II 1972 68 289. ' O J . C. Light J . Chem. Phys. 1964,40 3221. '' P. Pechukas and J. C. Light J . Chem. Phys. 1965 42 3281. '' A. B. Callear and P. M . Wood J.C.S. Faraday I I 1972 68 302. 8 3 A. C. Vikis and D. J. LeRoy Canad. J . Chem. 1972,50 595 Reactions of Atoms and Small Molecules 33 Phillips et dS4 have observed emission in the region 380-500 nm during the cadmium-photosensitized irradiation of Cd-NH mixtures.The emission was studied by a phase-shift method from which these authors report that for the process cd(53P0) + NH products (21) k = 1.7 f 0.3 x 10- l 2 cm3 molecule- ' s- ' (560 K). They further report the mean lifetime of the Cd(NH3)* complex as 4.9 f 0.2 x lO-'s. Two studies of the reaction of iron atoms with oxygen may be mentioned. Fontijn et a1.50,85 have described a fast-flow tubular reactor for use at high temperatures (up to 2000 K) and have employed this to study the reaction of Fe + 0 by atomic line absorption spectroscopy. They report that for the reaction Fe + 0 FeO + 0 (22) k = 3.6 & 1.4 x cm3 molecule-'s-' (1600 K). The same reaction has been studied by FeO emission spectroscopy in the region 10.4-16.3pm from shocked mixtures of Fe(C0,)-0 by Van Rosenberg and Wray.86 These latter authors report k 2 5 x lo-' cm3 molecule-' s-' (2400 K).Carbon and Lead.-A limited number of kinetic investigations have been reported for the Group IV atoms carbon and lead. Groth et ~ 1 . ~ ~ have extended to flow systems the use of atomic resonance absorption spectroscopy in the vacuum ultraviolet for the quantitative study of C(23PJ) reported hitherto for time-resolved static systems by Husain and K i r s ~ h . ~ ~ * ~ ~ Carbon atoms were generated in the flow by the reaction of active nitrogen with organic gases and it was demon-strated that the reaction of C + 0 provided a titration technique for carbon atoms. Hence these workers calibrated the line absorption of C(23P,) at 1 = 165.7 and 156.0 nm.It was found that the Beer-Lambert law was obeyed for up to 50% absorption for these transitions. Gosse et have monitored the C, Swann bands from a CO afterglow and shown that C,O is an intermediate in the formation of C,(A 3FIn). They report a rate constant for the reaction C + CO + M -% C,O + M (23) which is in sensible agreement with the previous result of Husain and Rose9' has described a study of 'hot' carbon atoms with H usinga recoil-product-analysis technique and concludes that the reaction between these species yields 8 4 P. D. Morten C. G. Freeman M. J. McEwan R. F. C. Claridge and L. F. Phillips, 8 5 A. Fontijn and S. C. Kurzius Chem. Phys. Letters 1972 13 507. 86 C. W. Von Rosenberg and K. L. Wray J. Quant. Spectroscopy Radiative Transfer, 1972 12 531.'' D. Kley N. Washida K. H. Becker and W. Groth Chem. Phys. Letters 1972 15 45. '' D. Husain and L. J. Kirsch Chem. Phys. Letters 1971 8 543. 89 D. Husain and L. J. Kirsch Trans. Faraday SOC. 1971,9 412. 90 F. Gosse N. Sadegi and J. C. Pebay-Peyroula Chem. Phys. Letters 1972 13 557. 9' Chem. Phys. Letters 1972 16 148. T. L. Rose J . Phys. Chem. 1972,76 1389 34 R. J. Donovan D . Husain and L. J. Kirsch 3CH2 almost entirely. Tschuikov-Roux et ~ 1 . ~ ~ have carried out a mechanistic study of the photolysis of C,02 at 1 = 147 nm in the presence of CH4 and Ar by chromatographic analysis of products. These workers describe evidence for the quenching of C(21D2) by Ar CO or CH,. In particular they argue that the data of Braun et al.93 for the interaction of C(2'D2) with CH4imply somewhat surprisingly that a high proportion (12/13) of the collisions are inelastic.The greater overall removal rate observed by Husain and approaching unit collisional efficiency would not lead to this conclusion. Rebbert and A u ~ l o o s ~ ~ have carried out analyses on the products of the photolysis of methane at I = 104.8 106.7 and 123.6 nm and report quantum yield data for the formation of CH and C(2'D2). The principal recent contribution to the detailed kinetic study of Group IV atoms in defined electronic states arises from the measurements of Husain and Littlerg6-" on the optically metastable electronically excited states Pb(61D2) and Pb(6'So) respectively 2.66 and 3.65 eV above the 63P0 ground state ofatomic lead.'" These atomic states were generated by the pulsed irradiation of tetra-ethyl-lead at very low pressures in the presence of added gases and monitored photoelectrically in absorption by time-resolved attenuation of atomic resonance Table 11 Second-order rate constants (k/cm3 molecule- s - ' 300 K) for the collisional remo*ial of Pb(6'So) and Pb(6lD2) by various gases (M) M He Xe H2 0 2 N2 co NO co2 N2O CH4 C2H2 CF4 C2H4 SF, PbEt, Pb( 6 ' S o ) -<2 x 10-15 < 10-14 1.2 k 0.3 x 10-lo 1.6 f 1.6 x 6.3 f 0.4 x lo-'' 2.1 * 0.2 x 10-'O 3.5 f 0.5 x 10-15 4.2 & 0.3 x 2.3 0.3 x lo-'' 2.3 f 0.3 x -= 10-14 < 5 x 10-l6 1.7 k 0.2 x 10-15 3.7 f 0.4 x lo-" Ref: 98 98 98 99 99 99 99 99 99 99 99 99 99 98 Pb(6 4) < 2 x lo-', <10-15 < 10- 14 < 10- 15 < 10- 1 4 1.1 k 0.3 x lo-'' 9.3 f 0.2 x 10-l2 9.2 & 0.8 x lo-" 4.5 k 0.8 x 10-l2 2.6 & 0.4 x lo-" 2.0 f 0.6 x lo-" < 10- l 4 < 10- 1 4 < 10- 1 5 5.6 f 1.2 x lo-" Ref: 96 96 96 96 97 97 97 97 97 97 97 97 97 97 96 92 E.Tschuikov-Roux Y. Ind. S. Kodama and A. W. Kirk J . Chem. Phys. 1972 56, 9 3 W. Braun A. M. Bass D. D. Davis and J. D. Simmons Proc. Roy. Soc. 1969 A312, 94 D. Husain and L. J. Kirsch Trans. Furuduy. Soc. 1971 67 3166. 9 5 R. E. Rebbert and P. Ausloos J. Photochem. 1972 1 171. 9 6 D. Husain and J. G. F. Littler Chem. Phys. Letters 1972 16 145. 9 7 D. Husain and J. G. F. Littler J.C.S. Furuduy 11 1972 68 2110.9 9 D. Husain and J. G. F. Littler J.C.S. Furuduy 11 1973,69 842. 3238. 417. D. Husain and J. G. F. Littler J . Photochem. 1973,1 327. l o o C. E. Moore Nat. Bur. Stand. Circular 467 'Atomic Energy Levels' Vols. 1-111 U.S. Government Printing Office Washington D.C. 1958 Reactions of Atoms and Small Molecules 35 radiationatA = 374.0 nm ( P ~ [ ~ s ( ~ P ; ) + 6p2('D2)]) and 500.5 nm (Pb[7s('P:)+ 6p2('So)]). This has led to a large amount of data for the collisional quenching of these two atomic states by various gases and these are summarized in Table 11. The main conclusion of this work is that the large spin-orbit coupling in the lead atom prevents the use of spin and orbital correlations for defined states of reactants and products normally employed for light atoms,"' and which were found to be successful in accounting for the collisionalprocesses that C(23PJ 2'D2, and 2lSO) undergo with molecules.94 Nitrogen and Phosphorus.-A number of reactions of nitrogen atoms with molecules have been studied by molecular emission.Golde and Thrush'02 have reported kinetic data on electronically excited nitrogen atoms N(22PJ) produced by the reaction N(24S,,2) + N2(A 3C,f) + N(22PJ) + N2(X 'Cg+) (24) in a flowing nitrogen afterglow by monitoring the atomic emission N(22PJ)--) N(24S3,2) at 346.6 nm the first positive emission of N2(B 311,-A 3Cu') and the NO 6 emission (C 2C+-X 211). By employing the absolute rate data for the col-lisional quenching of N(22PJ) by N 2 0 and O2 of Husain Kirsch and Wiesen-feld,lo3 Golde and Thrushlo2 describe absolute data for the quenching of this state by 0(23PJ) and N(24S3/2) namely k = 7 x 10- l1 and k = 1 x 10- l1 cm3 molecule- s- '.It was further found that k, < 5 x 10- ' cm3 molecule- ' s- '. Campbell and Nea11°4 report the rate constant for the removal of NO(B 211) by N24S3/2) of k - 2.5 x lo-'' cm3 molecule-' s-' by monitoring the NO /3 chemiluminescence (B 211-X 211) in a discharge flow system. Provencher and McKenney'" have described measurements on the emission from CN in a discharge flow system which yield for the process N + CN + M NCN* (electronically excited) (25) k 2 5 = 3 x cm6 molecule-2 s-'. Felder and Younglo6 have also studied the chemiluminescence of NO in a flow system and discuss the factors governing the relative yields of O(2lD2) and N2(u) from the reaction of N + NO.Groth et allo7 have described a detailed investigation of nitrogen-atom recombination in a slow-decaying Lewis-Rayleigh afterglow in a static system. Radiative recombination via the transitions N2(B 311g u' = 13 J'-+ A 3Cu+, u" J") and N2(a 'I& u' = 6 J' = 13 -+ X 'Cg+ u" J") was found to be charac-terizedbyabsoluterateconstantsof1.6 x 10- lgand 1.8 x cm3 molecule-' s-' respectively. A rate constant of 2.4 x cm6 molecule-2 s-' was found l o ' l o * R. J. Donovan and D. Husain Chem. Rev. 1970 70,489. M. F. Golde and B. A. Thrush Faraday Discuss. Chem. SOC 1972 no. 5 3 p. 233. D. Husain L. J. Kirsch and J. R. Wiesenfeld Faraday Discuss. Chem. SOC. 1972, no. 53 p. 201. I o 4 I. M. Campbell and S.B. Neal Faraday Discuss. Chem. SOC. 1972 no. 53 p. 72. I o s G. M. Provencher and D. J. McKenney Canad. J . Chem. 1972 50 2527. I o 6 W. Felder and R. A. Young J . Chem. Phys. 1972 57 572. O 7 K. H. Becker E. M. Fink W. Groth W. Jud and D. Kley Faraday Discuss. Chem. SOC., 1972 no. 53 p. 35 36 R. J . Donovan D. Husain and L. J. Kirsch for the three-body recombination (M = N2) into the levels v' = 9-12 of N2(B ,TIg). Total chemiluminescence from the B ,IIg state formed from col-lisional recombination was found to be characterized by a rate constant of k - 1 x cm6 molecule-2 s- '. Mandlemann Carrington and Younglo8 have employed the radiation of an N + 0 afterglow as a specific light source to photodissociate NO. From this they report a rate coefficient for the radiative recombination N + 0 NO(C 213 V' = 0) + NO(X 211 U" = 0) + h v (26) k y e = 2.9 x 10- l 8 cm3 molecule-' s-' (300 K).Further summed over all v", k26 = 1.5 Jacob and Winkler"' have employed the NO titration technique in a flow discharge for N atom determination coupled with cold trapping of products to measure the rate of the process 0.4 x 10- l 7 cm3 molecule-' s-'. N + SO -% so2 + . . a (27) where k was found to be the order of 5 x cm3 molecule-' s-' (300 K). Hand and Obenauf"' have also used the NO titration method together with time-of-flight mass spectrometry to measure the rate of the reaction N + C4N2 NC,N2* (28) for which it is reported that k 2 8 = 5.3 f 4.3 x lo-'' cm3 molecule-' s-'. An extensive body of data on the collisional removal of electronically excited phosphorus atoms P(32D,) and P(32PJ) respectively 1.40 and 2.32 eV above the P(34S3,2) ground state,'00 has been reported by Husain et al.'11-113 The electronically excited atoms were generated by the pulsed irradiation of PC1, at low pressures and monitored photoelectrically in absorption by attenuation of atomic resonance radiation at the wavelengths shown in Table 12a.The resulting Table 12a L/nm Transit ion 213.55 42P3j2 + 32D0 2 13.62 42P312 +- 32D$: 253.40 4=P312 +- 32PYi2 253.57 42P3j2 * 32P:12 rate data are presented in Table 12b. In general the J levels of the 2D state were not optically resolved during kinetic experiments ; one investigation' did result in the separation of J = 1/2 and 3/2 of P(32PJ) and this demonstrated equal M.Mandelmann T. Carrington and R. A. Young J. Chem. Phys. 1973,58 8 5 . A. Jacob and C. A. Winkler J.C.S. Faraday I 1972 68 2077. A. U. Acuna D. Husain and J. R. Wiesenfeld J . Chem. Phys. 1973 58 494. A. U. Acuna D. Husain and J. R. Wiesenfeld J. Chem. Phys. 1973 in the press. A. U. Acuna and D. Husain J.C.S. Furuduy 11 1973,69 5 8 5 . ' l o C . W. Hand and R. H. Obenauf jun. J . Phys. Chem. 1972.76 2643. 'I Reactions of Atoms and Small Molecules 37 Table 12b Rate constants (k/cm3 molecule- s- ' 300 K) for the removal of P(3'DJ) and P(32PJ) on collision with various atoms and molecules Collision partner He Ar Kr Xe H2 N2 0 2 co NO HCl C'2 co2 N2O PC1, p(32DJ) <5 x 10-l6 <5 x 10-l6 1.7 f 0.3 x lo-" 4.0 f 0.7 x 1.4 k 0.2 x lo-" 1.5 f 0.4 x lo-" 5.5 f 0.6 x lo-" 2.4 f 0.2 x lo-" 1.8 0.2 x 10- l 1 2.6 f 1.1 10-15 <5 x 10-l6 3.3 f 1.0 x 10-l2 1.2 f 0.2 x lo-" 9.7 f 0.9 x lo-" 1.1 * 0.1 x lo-" 7.3 5 0.8 x 10-15 3.9 5 0.7 x 10-13 1.5 f 0.1 x lo-'' CH4 C2H4 CF4 CF,H CF,CI SF 1.5 f 0.3 x C2H6 1.5 f 0.1 x lo-" 6.0 k 0.7 x lo-" 1.3 f 0.1 x lo-'' 8.7 f 0.7 x lo-" CH3-CH=CH2 C2H2 Ref: 112 112 112 112 111 112 111 112 112 113 113 112 112 111 112 112 113 113 113 113 113 113 113 p(32pJ) <5 x 10-l6 <5 x 10-l6 <5 x 10-l6 2.0 f 0.3 x 3.1 f 0.8 x <5 x 10-l6 2.6 & 0.2 x lo-" 7 +_ 6 x 3.0 f 0.5 x lo-" 6.0 f 0.3 x 2.9 f 0.4 x lo-" 7.3 5 1.9 x 3.1 f 0.6 x 1.1 f 0.1 x 10-l0 (2pJ) 1.1 5 0.2 x lo-'' ( J = 1/2) 1.1 0.3 x lo-'' ( J = 3/2) 2.8 f 0.5 x 4.2 f 1.2 x lo-" 1.9 f 0.2 x 2.0 f 0.3 x 2.4 f 0.5 x 2.7 f 0.5 x lo-" 5 x 10-15 1.4 f 0.2 x lo-'' 3.6 f 0.4 x lo-" Ref: 112 112 112 112 111 112 111 112 112 113 113 112 112 111 112 112 112 112 113 113 113 113 113 113 113 rates for the removal of the two J levels which appears to indicate that these close-lying levels are maintained in a Boltzmann distribution throughout reaction.'' For diatomic molecules and the linear triatomic molecules N,O and CO, it was found that the removal rates for the 2D and ,P states were in accord with the correlation of the spin and orbital symmetry of reactants and products assuming weak spin-orbit coupling and a collision complex of C , symmetry.For polyatomic molecules,' l 3 the removal rate constants for both P(3*DJ) and P(3,PJ) exhibited a good correlation with the ionization potential of the quenching gas over a wide range of potentials (9-19eV). The principal gap at present in our knowledge of rate data for the low-lying levels arising from the configuration P(3p3) is that of the 4S ground state. Oxygen Sulphur and Tellurium.-The large body of investigations on atomic kinetics in Group VI has been concerned primarily with oxygen atoms in the three low-lying states of the 2p4 configuration O(23PJ) 0(2'D,) and 0(2'5,), as expected for this aeronomically important species. There have also bee 38 R. J . Donovan D. Husain and L.J. Kirsch developments in methods of studying sulphur atoms both by resonance fluores-cence and spectroscopic marker methods which indicate a future development in detailed studies on S atoms in defined states for a wide range of fundamental processes. 0(2'S0). The forbidden emission at A = 557.7 nm from 0(2'S0)-+ O(2'0,) + hv continues to constitute the basis of kinetic methods for monitoring this optically metastable excited state. The temperature dependence of collisional quenching by simple molecules is the main advance that has taken place for this state. Welge and co-workers' ' 4*1 have employed the pulsed photolysis of CO,, followed by time-resolved atomic emission from 0(2'S0) whereas Slanger and co-workers'16 have used N,O as the parent molecule.The results from these investigations for quenching by molecular oxygen show very good agreement (Table 13). Further Welge and Atkinson" found enhancement of the emission by N and Ar to be independent of temperature. These authors report k, < 5 x lo-'' and k, < 5 x cm3 molecule-' s-'. Table 13 Rate constants (k) for the temperature dependence of the collisional quenching of 0(2lSO) Quenching gas k/cm3 molecule- ' s- ' Re.$ 114,115 1 - 11.0 0.8 kJ mol-' co2 3.3 x l o - ' ' exp 0 2 1 -7.1 0.8 kJ mol-' 4.9 x exp -7.2 1.2 kJ mol-' 4.0 x 10-"exp 115 116 Felder and Young' l 7 have employed the emission at 557.7 nm to study the quenching of 0(2'S0) generated from the pulsed photolysis of N,O at 147 nm in a flow system by ground-state oxygen atoms.Using the N + NO titration method as the source of O(Z3PJ) these authors report koJP = 7.5 x lo-' cm3 molecule-'s-' which is ca. 50% greater than the previously reported value.' 18,119 Felder and Young also conclude that kNeS < lo-' cm3 mole-cule- ' s- '.' l 7 They argue that the above rates for quenching by 0(23PJ) imply that the processes 0 + 0 + 0 -+ 0 + 0(2'S0) N + 0 + 0 + NO + 0(21S0) (29) (30) and N + N + 0 -+ N + 0(2'S0) (31) K. H. Welge A. Zin E. Vietzke and S. V. Filseth Chem. Phys. Letters 1971 10 13. 'Is P. Atkinson and K. H. Welge J . Chem. Phys. 1972 57 3689. 'I6 T. G. Slanger B. J. Wood and G. Black Chem. Phys. Letters 1972 17,401. W. Felder and R. A. Young J . Chem. Phys. 1972 56 6028 Reactions of Atoms and Small Molecules 39 are characterized by rate constants of 4.8 x (29) 2.56 x (30) and 1.3 x (31) respectively.Welge et al.'" have reported corrected values for quenching by CO and NO namely k, = 1.0 x and k = 8.0 x lo-'' cm3 molecule-' s-'. Lawrence12' reports the quantum yields (Q) for the production of 0(2'S,) from the photolysis of C02 as a function of wavelength and finds a( - 110 nm) = 1.0 (D(90 nm) = 0.3 and Q(121.6 nm) = 0.15. 0(2'D2). The principal development for the direct kinetic investigation of 0(2'D2) has been the design of a method by Heidner Husain and Wiesenfeld'22 for monitoring this state in absorption by time-resolved attenuation of atomic resonance radiation at A = 115.2 nm [0(3'D! + 2'D2)]. O(2'0,) was generated by the repetitively pulsed irradiation of ozone at low pressure and monitored by signal-averaging of the photoelectric pulses resulting from line absorption.This technique is a factor of ca. lo2-lo3 more sensitive than the previous main method for studying this state directly and which employed the highly forbidden emission, 0(2'D2)-+ O(23P2) a t A = 630nm.'23 Heidner et ~ 1 . ' ~ ~ ~ ' ~ ~ ' ~ ~ have obtained absolute quenching data for the removal of this state with a range of collision partners (Table 14). Where a comparison can be made with the absolute data of Table 14 Rate data for the collisional quenching of O(2'0,) by various gases studied by attenuation of atomic resonance radiation at A = 115.2 nm [0(3'D:) + 0(2'D,)] and at 300 K k/cm3 molecule- ' s- ' 7.0 k 0.5 x lo-'' 6.9 0.6 x lo-" 7.3 _+ 0.7 x lo-'' 3.0 & 0.3 x lo-'' 2.7 f 0.2 x lo-'' 2.7 0.3 x lo-'' 1.8 & 0.2 x lo-'' 9.4 k 0.8 x lo-" 2.3 0.2 x lo-'' 3.1 & 0.4 x lo-'' 4.0 0.4 x lo-'' G 1.5 x 10-15 2.1 * 0.2 x lo-'' 2.2 & 0.2 x lo-'' Ref.122 124,125 124,125 124,125 124,125 124,125 122,124,125 126 126 1 26 126 126 126 126 R. A. Young and G . Black Planet. Space Sci. 1966 14 113. ' I 9 R. A. Young and G. Black J . Chem. Phys. 1966 44 3741. "O S. V. Filseth F. Stuhl and K. H. Welge J . Chem. Phys. 1972 57 4064. I * ' G . M. Lawrence J . Chem. Phys. 1972 57 5616. R. F. Heidner tert. D. Husain and J. R. Wiesenfeld Chem. Phys. Letters 1972 16, 530. J. Noxon Canad. J . Chem. 1969,47 1873; J . Chem. Phys. 1970 52 1852. R. F. Heidner tert. and D.R. Husain Nature 1972 241 10. R. F. Heidner tert. D. Husain and J . R. Wiesenfeld J.C.S. Faraday IZ 1973 in the press. I z 6 R. F. Heidner tert. and D. Husain Internat. J . Ckem. Kinetics 1973 in the press 40 R. J . Donovan D . Husain and L. J. Kirsch N ~ x o n ' ~ ~ (O, N, CO and CO,) there is reasonable agreement with the exception of the rate for CO,. Noxon' 2 3 originally obtained an anomalously low value for CO (k,, = 3.0 x 10- l 2 cm3 molecule- s- ') which unfortunately, was the basis of later extensive discussion of an intermediate CO in the atmos-pheric chemistry of Mars and Venus. More recently Clark and Noxon12' have modified their experimental method for monitoring O(2l0,) in emission and their resulting relative-rate data now confirm the rapid quenching by CO .Thus they have found k, k, kC0 = 0.55 0.45 1.00 (O'D emission) and k, k, kcOz k, = 0.55 0.4 1.00 0.2 [from O,(b 'Cg+) emission]. Steady-state photolysis coupled with final-product analysis also continues to be widely employed for the determination of relative-rate data for the collisional removal of O(2'0,). Greenberg and Heicklen'28 have quantified the relative extents to which the different pathways contribute to the overall process O(2l0,) + CH products (32) following the photochemical production of O(2l0,) from N,O (A = 231.9 nm). They have further found that for the processes O(2l0,) + N,O 5 N + 0, O(2l0,) + N,O A 2N0, (33) and (34) k,,/(k33 + k3,) = 2.28 f 0.20 and that this ratio is reduced to the value of 1.35 0.3 on the removal of excess translational energy by collisions with helium.Heicklen et ~ 1 . ' ~ ~ further report k,,/k, = 0.69 0.05 which is in-creased to 0.86 & 0.06 on moderation with helium. This latter value is in better agreement with that of Scott et ~ 1 . ' ~ ' (k3,/k3 = 1.01). The molecular dynamics of reactions (33) and (34) are discussed by Simons et who measured the distribution of vibrational energy in NO following the flash photolysis of N,O. Simonaitis and Heicklen13 have also studied the steady photolysis of N,O in the presence of H,O CO and He to investigate the relative rates of the reactions 0(2102) + H,O -% 2 0 H (35) 1 2 ' I. D. Clark and J. F. Noxon J . Chem. Phys. 1972 57 1033. 1 2 9 R. Simonaitis R. I . Greenberg and J . Heicklen Internat.J . Chem. Kinetics 1972 4, 130 P. M. Scott K. F. Preston R. J . Anderson and L. M. Quicla Canad. J . Chem. 1971, '" C . Boxall J. P. Simons and P. W. Tasker Faraday Discuss. Chem. Sac. 1972 no. 5 3 , ' 3 2 R. Simonaitis and J . Heicklen Internat. J . Chem. Kinetics 1972 4 529. R. I . Greenberg and J. Heicklen Internat. J . Chem. Kinetics 1972 4 417. 497. 49 1808. p. 182 Reactions of Atoms and Small Molecules and 41 o(210,) + co o(2313,) + c o , for which they report ( - 5.0 kRJTmol- ' k3&6 = 2.6exp This ratio at 300 K (0.35) may be compared with that derived from the absolute data of Heidner et al.124*125 (Table 14) for the overall quenching by these two molecules where k,,o/kco = 4.1 and where rapid overall removal by H,O is clearly established.The results of the two investigations may indicate a contribu-tion to the collisional relaxation of O(2'0,) to the ground state by H,O. Schumacher and c o - w ~ r k e r s ' ~ ~ ~ ~ ~ have employed ozone as the photo-chemical source of O(2'0,) and report relative rates for removal of the excited atom of 0 0 N Xe Ar He = 1.0 0.23 0.19 0.18 0.043 0.012 and 1.0 0.23 0.20 0.17 0.039 0.01 for steady photolysis at 313 and 253.7 nm respectively. The rate for helium is clearly high by ca. three orders of magnitude when compared with the direct absolute data of Heidner et al. (Table 14).12, Loucks and Cvetanovic' 35 have studied the photolysis of C0,-N,O mixtures at A = 163.3 nm. This work yielded kCO2/kNzO = 0.80 for the removal of 0(2l0,), in agreement with both previous work and the absolute data of Heidner et a1.(Table 14),' ,4-' 26 and indicates that O(2'0,) undergoes physical quenching with CO and chemical reaction with N,O. These authors'36 have investigated the photolysis of CO at 163.3 nm in detail especially with regard to a material balance. This work is a very useful basis for considering various inconsistencies in the earlier literature. Cvetanovic and co-workers' 3 7 further report kN,,/ kneopentane = 0.145 0.010 following the photolysis of N,O and have shown that O(2 '0,) undergoes reaction with these two molecules. Michaud and Cvetano-vic13* have quantified the main reaction pathways that 0(2'D,) generated in this system undergoes with cyclopropane. Lissi and Heicklen' 39 have presented a detailed investigation of the steady photolysis of 0 in the region 228.8-285.0 nm and have concluded that O(2'0,) is not generated in the chain step.Giachardi and Wayne'40 have studied reactions of O(2'0,) from the photolysis of ozone (A = 253.7 nm) by monitoring O(23PJ) using atomic resonance fluores-cence. The system was sampled after both 0(2'D2) and 0 2 ( b lEg+) had reacted. Details of quantum yield measurements are given. Pathways for chemical ' 3 3 E. Castellano and H. J. Schumacher Z . ph-vs. Chem. (Frankfurt) 1972 76 258. 1 3 4 G. Von Ellerieder E. Castellano and H . J . Schumacher Z . phys. Chem. (Frankfitrr), 1 3 ' 1 3 6 '" G. Paraskevopoulos V. B. Symonds and R. J. Cvetanovic Canad. J . Chem. 1972,50, 1 3 ' P. Michaud and R. J. Cvetanovic J . Phys. Chem.1972 76 1375. 1 3 9 E. Lissi and J. Heicklen J . Photochem. 1972 I 39. I4O b. J. Giachardi and R. P. Wayne Proc. Roy. SOC. 1972 A330 131. 1972 76 240. L. F. Loucks and R. J . Cvetanovic J . Chem. Phys. 1972 56 1682. L. F. Loucks and R. J. Cvetanovic J . Chem. Phys. 1972 56 321. 1838 42 reaction of O(2l0,) + 0 are described and it is concluded that the process R. J. Donovan D. Husain and L. J. Kirsch O(2l0,) + 0 -+ O(23P') + O,(b lZg+) (37) takes place on 50-60% of the quenching collisions. In general Wayne's141 article in the Faraday Discussion provides a useful review of the reactions of excited species in the photolysis of ozone. McCullough and McGrath14 have measured the vibrational distribution in O,(X ?Zg-) following the ultraviolet flash photolysis of ozone and conclude that the levels Y" = 13-15 are formed in the deactivation of O(2l0,) with 0 with an efficiency (a) of 0.3 < a < 0.5.A detailed measurement on the vibrational distribution of 0 in this same system has been given by Webster and Blair,'43 following the reaction of O(2lD2) + 0 , who discuss the results in terms of a model for the statistical break-up of an 0, complex. Fisher and B a ~ e r ' ~ ~ have published an excellent theoretical paper on the quenching of O(2l0,) by N . The model involves curve-crossing of covalent states and can also be applied to the vibrational relaxation of N by O(2,PJ) and to the unimolecular decomposition of N20. The principal result for O(2l0,) is that less than 5 % of the electronic energy should appear as vibration in N, but that the molecule is likely to be rotationally excited.This paper'44 is of especial use in the consideration of a number of aspects of atmospheric chemistry. 24 Finally Lin and co-workers have developed a number of pulsed lasers arising from the reactions of 0(2'0,) generated from the flash photolysis of ozone with various molecules. HCl and HF lasers have been constructed from the reactions of O(2l0,) with ha loge no me thane^.'^^-'^^ It is envisaged that the vibrationally energized diatomic molecule is eliminated from the highly vibrationally excited halogenomethanol initially formed on insertion of O(2'0,). Similarly Brus and Lin'48 have observed CO laser emission from the reaction of O(2l0,) + C302 and also from O(2'0,) + XCN (X = C1 Br I or CN).14' O(2,PJ).Resonance fluorescence at 3 = 130 nm [0(3jS1) + O(23P,)] especially in the time-resolved mode following flash photolysis has continued to be employed as a powerful tool for direct kinetic investigations of O(23PJ). Davis et a1.''' have used this technique to study the recombination reaction 0 + 0 + M -L 0 + M (38) over the temperature range 20@-346 K and obtained the result 4.24 & 0.19 kJ mol-' k$; = 6.57 5 0.59 x 10-35exp ( RT ) cm6 molecule-2 s-1 l 4 I 1 4 2 D. W. McCullough and W. D. McGrath Chem. Phys. Letters 1971 12 98; J . Phoro-1 4 3 H. Webster tert. and E. J. Blair J . Chem. Phys. 1972,57 3802. 144 E. R. Fisher and E. Bauer J . Chem. Phys. 1972,57 1966. 1 4 5 L. E. Brus and M. C. Lin J . Phys. Chem. 1971 75 2546. 146 M. C. Lin J .Phys. Chem. 1972,76 811. 14' M. C. Lin J . Phys. Chem. 1972,76 1425. 14* M. C. Lin and L. E. Brus J . Chem. Phys. 1971 54 5423. 149 L. E. Brus and M. C. Lin J . Phys. Chem. 1972,76 1429. R. P. Wayne Faraday Discuss. Chem. SOC. 1972 no. 53 p. 172. chem. 1973,1 241. 5 0 R. E. Huie J. T. Herron and D. D. Davis J . Phys. Chem. 1972,76,2653 Reactions of Atoms and Small Molecules 43 They have further found the relative rates for process (38) with M = He Ar or N of 0.92 1.0 1.6 at 298 K and for Ar and N, of 1.0 1.7 at 218 K. Slanger and co-~orkers''~ have employed this method for a careful re-examination of the recombination reaction O + C O + M L C O + M (39) This slow process is particularly prone to effects of impurities. Slanger et al.' report cm6 molecule-2s-' ( - 18.1 & i;kJ mol-k$ = 6.5 x 10-33exp Rate constants at T = 296 K of 2.3 x are also given for M = N and CO, respectively.'51 These slow rates should in the opinion of the authors be considered as the most definitive yet obtained.Davis et ~ 1 . ' ' ~ and Kury10"~ have studied the addition of O(23PJ) to ethylene by resonance fluorescence and have compared the results experimentally with those derived from mass spectrometry and NO + 0 chemiluminescence. The value of the resulting rate constant to emerge from these techniques is given by and 6.2 x cm3 molecule- ' s- -4.72 f 0.13 kJmol-' k = 5.42 & 0.3 x exp Davis et al.' 54 have also employed resonance fluorescence to quantify the rate of addition of O(23PJ) to but-1-ene in the temperature range 190491 K and have found that the data could not be satisfied by a linear Arrhenius plot.Concurrent abstraction and addition by the atom was assumed following which they report 1 ( - 0.2 & yTkJ mol- ' kadd = 3.7 & 1.8 x 10-12exp and cm3 molecule- s- ',' 54 1 [ -8.24 & y kJ mol- ' kabs = 1.6 & 0.9 x lO-"exp Clyne and Cruse"' have also employed resonance fluorescence on O(23PJ) in a discharge flow system and report that k, = 6.1 & 0.6 x 10- l 2 cm3 molecule-' s- (298 K) for the reaction O+NO,*O,+NO (40) in good agreement with previous data. Very recently Davis et ~ 1 . ' ~ ~ have investigated the kinetics of reaction (40) using atomic resonance fluorescence 1 5 * D. D. Davis R. E. Huie J. T. Herron M. J. Kurylo and W. Braun J . Chem.Phys., l S 3 M. J. Kurylo Chem. Phys. Letters 1972 14 117. T. G. Slanger B. J. Wood and G. Black J . Chem. Phys. 1972,57 233. 1972,56,4868. R. E. Huie J. T. Herron and D. D. Davis J . Phys. Chem. 1972 76 331 1. M. A. A. Clyne and H. W. Cruse J.C.S. Faraday 11 1972,68 1281. l S 6 D. D. Davis J. T. Herron and R. E. Huie J . Chem. Phys. 1973 58 530. 5 44 R. J . Donovan D . Husain and L. J. Kirsch following flash photolysis and obtained k, = 9.12 f 0.44 x cm3 mole-cule-' s-' which was found to be independent of temperature in the range 23&339 K. The result is in sensible agreement with that of Clyne et al.'" Chemiluminescence from 0 + NO has also been employed recently to obtain kinetic data for O(23P,). Stuhl and Niki'57,'58 have obtained rate constants for a number of second- and third-order reactions using this chemiluminescence as well as that from 0 + COY in the time-resolved mode following pulsed vacuum-U.V.photolysis. Their results are presented in Table 15. These ~ o r k e r s ' ' ~ have Table 15 Rate data for Op3 P,) derived from time-resolved chemiluminescence at 300 K from 0 + NO and 0 + CO following vacuum-ultraviolet pulsed photolysis Third-order reactions' 5 7 Reactants k/cm6 molecules-2 s-' O + N O + N O 1.5 x 10-3l k 10% O + N O + H e 6.65 x 10-32 f 10% 0 + 0 + 0 6.4 x 10-34 f 25% 0 + 0 + N 5.4 10-34 _+ 25% 0 + 0 + co 6.7 10-34 25% O + C O + N 2.2 x 10-36 f 25% 0 + CO + co 0 + N + N, 0 + co + co 3.2 x f 25% 0 + CO + He 1.7 x k 25% 9 x 10-36 5 x 10-38 Second-order reactions' 5 8 Reactants k/cm3 molecule- s- ' 0 + C,H, 0 + C,D, 0 + C2H4 1.31 x 10-13 + 5 -10% 1.31 x 10-13 + 5 -10% 6.3 x 10-13 + 5 -10% 0 + C3H6 3.6 x + 5 -10% also re-investigated the rates for the addition of O(z3PJ) + C2H or C2D4 using the same technique and have found kC2H4 = 6.25 f 0.63 x 10- '' and kCZD4 = 5.6 f 0.56 x cm3 molecule-' s-'.This confirmed {heir earlier measure-ments for thesequantities(Tab1e 15) which are slightly smaller than those reported by Davis et a1.ls3 Atkinson and Cvetanovic'60 have employed phase-shift measurements of the NO2 afterglow following modulated generation of O(23PJ) in a flow system by the mercury-photosensitized decomposition of N20. They report Arrhenius parameters (Table 16) for the addition of oxygen atoms to olefins.The value for 0 + C,H4 at 300 K (5.1 x cm' molecule-' s- ') is in sensible agreement with that of Stuhl and Niki'59 at this temperature. Atkinson and Cvetanovic'60 have also obtained a rate constant for the recombination of Is' F. Stuhl and H. Niki J . Chem. Phys. 1971,55 3943. l s 8 F. Stuhl and H. Niki J . Chem. Phys. 1972 55 3954. l S 9 F. Stuhl and H. Niki J . Chem. Phys. 1972 57 5403. I6O R. Atkinson and R. J. Cvetanovic J . Chem. Phys. 1972 56 432 Reactions of Atoms and Small Molecules 45 Arrhenius parameters for the addition of O(23PJ) to olejns from phase- Table 16 sh@ measurements of the NO, OleJn 10' ' ~ / c r n ~ molecule- ' s - ' E/kJ mol-' Ethylene Propene But- 1 -ene Isobutene 1.3 1.1 1.0 1.0, 8.1 k 0.4 4.3 k 0.4 3.4 & 0.4 0.0 & 1.7 0 + NO + M of cm6 molecule- s- ' (6.7 f 0.; mol- ' k = 7.2 x 10-33exp McCrumb and Kaufman' 61 have studied the reaction of 0 + O3 in the tempera-ture range 2 6 9 4 0 9 K from the thermal decomposition of O3 in a flow system using the NO afterglow.They report a rate constant of k = 1.05 & 0.18 x lo-'' exp - 17.9 f 0.42 kJ mol- ' cm3 molecule- s-for reaction. This value is in good agreement with recent data of Heicklen et al. - 18.0 kJ mol- ' k = 1.2 x lo-" exp ( RT ) cm3molecule-1 s-1 A number of kinetic processes that O(23P,) undergoes have been studied by employing the e.p.r. atomic spectral intensity often coupled with other analytical methods such as mass spectrometry. Bonanno et have investigated the reaction of O(23P,) with benzene in the temperature range 255-305 K using a fast-flow system and report a rate constant of cm3 molecule- ' s- ' ( - 18.4 1- i k k J mol- ' k = 3.8 1- 1.5 x 10-13exp They found no significant kinetic isotope effect with C,D,.Timmons et have investigated the kinetics of the processes 0 + (CH3),0 -% OH + CH20CH3 (41) and 0 + CH30H -% OH + CH,OH and report [ - 11.9 & :LkJ mol- ' k, = 5.0 & 1.0 x lo-' exp ''I J. J. McCrumb and F. Kaufman J . Chem. Phys. 1972,57 1270. 1 6 ' D. C. Krezenski R. Simonaitis and J . Heicklen Inrernat. J . Chem. Kinetics 1972 3, 467. 1 6 3 R. A. Bonanno P. Kim J.-H. Lee and R. B. Timmons J . Chem. Phys. 1972,57 1377. H. F. Lefevre J. E. Meagner and R. B. Timmons Znternar. J . Chem. Kinetics 1972, 4 103 46 R. J. Donovan D.Husain and L. J. Kirsch and cm3 molecule- ' s- ' ( -9.5 &:; kJ mo1-l k42 = 1.70 & 0.66 x 10- l 2 exp Mack and Thrush' have employed e.p.r. spectroscopy chemiluminescence, and product analysis for a study of the reaction of 0 + CH,O in a flow system. Atomic abstraction, 0 + CH,O 5 HCO + OH (43) is found to proceed with a rate characterized by k, = 1.5 0.15 x molecule-' s-'. Relative rates for the subsequent reactions of HCO, cm3 0 + HCO -+ OH + CO (4) 0 + HCO -+ H + CO, (45) and H + HCO -+ H + CO, were found to be given by k, k, k, = 0.54 0.46 0.40. Herbrechtsmeir and Wagner'66 have characterized the rate of the 0 + allene reaction in the tem-perature range 275-375 K and have found (46) cm3 molecule- ' s- ' ( - 6.7 :Tmol- ' k z 7.8 x lo-' exp Davis and c o - ~ o r k e r s ' ~ ~ report rate constants for the addition of oxygen atoms generated in a flow discharge to halogenoethylenes.Mass spectrometry was employed for analysis and the results are given in Table 17. Hand and Table 17 Rate constants for the addition O ~ O ( ~ ~ P ) to halogenoethylenes at 307 K Halogenoeth ylene k/cm3 molecule- * s-' C2H3F 3.95 _+ 0.63 x C2H3CI 8.68 _+ 0.40 x C,H,Br 8.15 f 0.57 x 1,l -C,H,F 3.64 _+ 0.30 x l,%-C,H,F 4.48 +_ 0.57 x Obenauf' have employed a similar method involving time-of-fligh t mass spectrometry to study the reaction of 0 + dicyanoacetylene and report a rate constant of k = 1.1 & 0.3 x 10- l 5 cm3 molecule-' s-' for this process. Jacob ' 6 5 G. P. R. Mack and B. A. Thrush J.C.S.Faraday I 1973 69 208. P. Herbrechtsmeir and H. Gg. Wagner Ber. Bunsengesellschaft phys. Chem. 1972, 76 5 17. R. E. Huie J. T. Herron and D. D. Davis Infernat. J. Chem. Kinetics 1972 4 521. "' 1 6 ' C. W. Hand and R. H. Obenauf jun. J . Phys. Chem. 1972 76 269 Reactions of Atoms and Small Molecules 47 and Wink1e1-l~~ have investigated the reaction of 0 + SO3 in a flow discharge. Oxygen atoms were generated by the N + NO titration and products were analysed following trapping at low temperatures. The results may be sum-marized by the rate constant for reaction of cm3 molecule- ' s- ' ( -4.2 yTmol-' k = 3 x 10-'5exp in the temperature range 300-500 K. McNeal et ~ 1 . ' ~ ' have employed the photoionization of molecular nitrogen to investigate the quenching process for which they report k47 = 3.5 & 1.4 x lo-'' cm3 molecule-' s-' which may be considered within the context of Fisher and B a u e r ' ~ ' ~ ~ theoretical calculations.Bevan and Johnson' 71 have investigated the kinetics of ozone formation following the pulsed radiolysis of molecular oxygen using the 0 absorption intensity for analysis. They postulate the involvement of two states of O, the first formed from the recombination of 0 + 0 + 0 which then relaxes to the second form on collision. Deactivation rates for this process are reported. The details of the vibrational product distribution in CO following the reaction of 0 + CS have been further investigated by Smith and c o - w o r k e r ~ ' ~ ~ and this has been extended to the reaction of 0 + CSe.'73 0 Atoms were generated in a flow discharge and vibrationally excited CO was monitored in emission in the infrared.With CS levels up to u" = 15 were populated reaction into u" = 13 being most probable;17 with CSe CO(u" < 20) was produced the relative rate into u" = 18 being greatest. Smith et ~ 2 1 . ' ~ ~ also report a rate coefficient for the reaction o + C S ~ SeO + C S ~ (48) of k4* 2 2 x lo-' cm3 molecule-' s- ' from flash photolysis experiments. The vibrational product distribution in CO from 0 + CS has also been investigated by F o ~ t e r ' ' ~ using a CW laser and he has found that the level 0'' = 12 f 1 was most highly produced in clear agreement with Smith et ~ 1 . l ~ ~ Felder Morrow and Young' 75 have obtained quantitative kinetic data for the quenching of CO(a 311) by O(23PJ).The oxygen atoms were generated by the 0 + NO titration and CO(a 313) by a Tesla discharge the (0,O) and (1,O) transitions of the forbidden Cameron system [CO(a 311-X 'Z')] being monitored in emission. These experiments yielded quenching constants of k,.= = 1.9 x 10- l o and k,,= = 2.1 x cm3 molecule- ' s- '. Shackleford et ~ 1 . ' ~ ~ have A. Jacob and C. A. Winkler J.C.S. Faraday Z 1972,68,2077. 1 7 0 R. J. McNeal M. E. Whitson jun. and G. R. Cook Chem. Phys. Letters 1972,16,507. 1 7 ' P. L. T. Bevan and G. R. A. Johnson J.C.S. Furaday I 1973,69 216. G. Hancock B. A. Ridley and I. W. M. Smith J.C.S. Faraday II 1972 68 2117. 1 7 3 C. Morely B. A. Ridley and I. W. M. Smith J.C.S. Faraday II 1972 68 2127. 1 7 ' K. D. Foster J .Chem. Phys. 1972 57 2451. '" W. Felder W. Morrow and R. A. Young Chem. Phys. Letters 1972 15 100. W. L. Shackleford F. N. Mastrup and W. C. Krege J . Chem. Phys. 1972 57 3933 48 R. J. Donovan D. Husain and L. J. Kirsch monitored the vacuum-u.v. chemiluminescence emission of CO(A ' rI-X 'C+) from the reaction of 0 + C,O in a flow system. C,O was generated by the flash photolysis of C302 in this environment. An overall rate for the process 0 + c 2 0 ~ 2 c 0 (49) of k, = 9.5:;: x 10- '' cm3 molecule-' s-' was found and that for 0 + C,O CO(A 'rI) + co (50) estimated as 10- "-10- cm3 molecule- s- '. These authors also report collisional quenching rates for CO(A Ill). Matsuda et a1.177-'79 have investi-gated the oxidation of carbon monoxide by oxygen atoms behind shock waves in the presence of metal carbonyls.CO was monitored by i.r. emission and metal oxides by mass spectrometry. It was found that the 0 + CO recombination was catalysed by the metal atoms. Simonaitis and Heicklen'80 have also studied the 0 + CO recombination following the mercury-photosensitized decomposi-tion of N,O. The recombination was studied by competition with 2-trifluoro-methylpropene in the temperature range 2 9 8 4 7 2 K. Kinetics intermediate between second and third order were found and the results interpreted in terms of surface crossing of the initially formed COJ3B,) with CO,('B,). Similar kinetics for this reaction have been found by DeMore,18' who has studied this process in competition with the recombination of 0 + 0 + M light absorption by 0 being measured.The third-order recombination rate constant for 0 + CO (kM=C02 = 5.0 x cm6 molecule-2 s-') was found to be in sensible agreement with the data of Slanger Wood and B1a~k.l~' DeMore'8','82 has employed a similar method to determine relative rates for 0 atom addition to olefins and reports kCzHs kC3H8 kbut-l-ene = 1 20 20. S and Te. Davis et al. 183*184 have employed time-resolved resonance fluorescence in the vacuum-u.v. to monitor S(33PJ) generated from the flash photolysis of COS-CO mixtures. The rate of the reaction with 0 was investigated in the temperature range 2 5 2 4 2 3 K yielding cm3 molecule- s - ( -0.0 & yTkJ mol- ' k = 2.24 & 0.27 x 10- l 2 exp This study also included the monitoring of product O(23PJ) by resonance fluorescence.The same method'84 was applied to the reaction of S(33P,) with 17' T. P. J. Izod G. B. Kistiakowsky and S. Matsuda J . Chem. Phys. 1972 56 1083. 1 7 8 S. Matsuda J . Chem. Phys. 1972 57 807. 17' S. Matsuda J . Phys. Chem. 1972 76 2833. R. Simonaitis and J . Heicklen J . Chem. Phys. 1972,56 2004. W. B. DeMore J . Phys. Chem. 1972 76 3527. W. B. DeMore Chem. Phys. Letters 1972 16 608. 1 8 3 D. D. Davis R. B. Klemm and M. J. Pilling Internat. J . Chem. Kinetics 1972,4 367. l S 4 D . D. Davis R. B. Klemm W. Braun and M. J. Pilling Internat. J . Chem. Kinetics, 1972 4 383 Reactions of Atoms and Small Molecules ethylene in the temperature range 2 1 8 4 2 K yielding 49 -6.6 & 0.3 kJ mol- k = 7.13 & 0.74 x lo-' exp ( RT ) cm3 molecule-1s-1. Donovan and Little185 have also studied the reaction S + 0 by time-resolved atomic absorption of resonance radiation following flash photolysis.This work yields k = 1.7 & 0.3 x lo-' (295 K)cm3 molecule-' s-l in good agreement with the results of Davis et aI.'84 Donovan et a1.ls6 have applied the NS spectroscopic marker method de-veloped by Donovan and Bre~kenridge,'~~ to measure relative quenching rates of S(31D2) with a range of collision partners. The method is very sensitive on account of the intense C + X transition of NS at 230 nm,'87 and the resulting kinetic plots obtained following the flash photolysis of COS-N,O-added-gas mixtures demonstrate the reliability of the method. The rate data resulting from this investigation are presented in Table 18. Table 18 collision partners derived from the NS spectroscopic marker technique Relative rate data for the collisional removal of S(3'D2) by various Collision partner (M) c H4 C2H6 CH4 co2 N2 H2 NO co Ar Kr Xe I 0.17 0.076 0.24 0.68 0.19 0.062 0.22 0.0097 0.028 0.16 Donovan and co-workers'88 have observed Te(SID,) in absorption by plate photometry at 175.8 nm following the flash photolysis of TeD .Further, Donovan and Little189 have carried out a detailed kinetic investigation of the spin-orbit states Te(53P,) and Te(s3Po) respectively 4751 and 4707 cm- above the S3p2 ground state.'" The tellurium atoms were generated by the flash photolysis of H,Te and monitored in absorption by time-resolved attenuation of resonance radiation at the wavelengths 238.40 nm [5~~6s(~S:) + 5p4(3P0)] and R.J. Donovan and D. J. Little Chem. Phys. Letters 1972 13 488. no. 53 p. 21 1. R. J. Donovan and W. H. Breckenridge Chem. Phys. Letters 1971,11 520. R. J. Donovan D. J. Little and J. Konstantatos J. Photochem. 1972 1 86. l a 6 D. J. Little A. Dalgeish and R. J. Donovan Faraday Discuss. Chem. Society 1972, l S 9 R. J. Donovan and D. J. Little J.C.S. Furaduy 11 1973 in the press 50 R. J. Donouan D. Husain and L. J. Kirsch 238.65 nm [5~~6s(~S:) t- 5p4(3Pl)J in order to monitor the J = 0 and J = 1 levels. The experiments indicate that these levels which are only separated by 44 cm- I are maintained in an equilibrium distribution throughout reaction. The resulting rate data are presented in Table 19. The quenching cross-sections Table 19 Rate constants (k) and collisional quenching cross-sections (0) for Te(s3P1) and Te(53p0) Quenching gas k/cm3 molecule- s- O/A2 H2 1.03 & 0.15 x lo-" 0.58 D2 8.8 _+ 6.5 x lo-'' 6.9 x 10-4 0 2 1.28 & 0.55 x 2.6 x 10-3 He 3.0 x lo-'' ~ 2 .4 x 10-4 Ar 1.38 f 0.28 x lo-'' 3.0 x 10-4 Xe 62.7 x 10-15 G8.6 x refer to the sum for these quantities for both spin-orbit states on collision with a particular gas. Particularly striking is the large isotope effect for H and D,, which is accounted for in terms of an energetically more favourable electronic-to-vibration energy-transfer process for H (u" = 1) compared with D (u" = 1). Fluorine Chlorine Bromine and Iodine.-A limited amount of kinetic data has been described for fluorine atoms.Kolb and Kaufman'" have employed a flow discharge system with molecular beam-mass spectrometric analysis of intermediates including the fluorine atom. They report a rate constant of k = 4.0 x 10- l 6 cm3 molecule- s- ' for the reaction of this atom with CCl,. Kompa and Wanner' have analysed the shape of the time-resolved laser pulse in the i.r. from HF following the reaction of fluorine atoms with hydrogen-containing molecules. F Atoms were generated from the flash photolysis of WF . These authors report the rate constants for the systems F + H,, F + HCl, k = 6.3 x lo-" cm3 molecule-'^-^ k = 2.5 x lo-" cm3 molecule-' s-' and F + CH, k = 2.5 x lo-'' cm3 molecule-'^-^ Czarnowski and Schumacher ' 92 have investigated the thermal decomposition of F,O in a static system and have obtained a rate constant of cm3 molecule- ' s- ' ( - 57.3 & i;kJ mol- ' k = 8.6 x 10-'4exp for the reaction F + F,O -% F + FO (51) C.E. Kolb and M. Kaufman J . Phys. Chem. 1972,76,947. K. L. Kompa and J. Wanner Chem. Phys. Letters 1972 12 560. 1 9 ' l g 2 J. Czarnowski and H. J. Schumacher Chem. Phys. Letters 1972 17 235 Reactions of Atoms and Small Molecules 51 Clyne et a1.1g3 have observed the states B 311 (0') in emission formed from the recombination of F(22P3/2) with iodine and bromine atoms in the presence of 0 2 ( a 'Ag) and O,(b 'Xgf) in a flow system. A three-body recombination mechan-ism followed by energy transfer on collision is discussed. The major recent contribution to the kinetics of chlorine and bromine atoms is the work of Clyne and Cruse'94 on the study of C1 and Br atoms in a flow discharge system using atomic resonance fluorescence in the vacuum-u.v.This work is highly detailed from both the spectroscopic and kinetic points of view. The resulting kinetic data are given in Table 20. Bernard and Clyne"' have also Table 20 Rate data for chlorine and bromine atoms derived from atomic resonance Jluorescence spectroscopy in the vacuum ultraviolet at 298 K Reaction C1 + ClNO -+ NO + C1, Br + ClNO -+ NO + BrCl C1 + BrCl -* C1 + Br C1 + Br -P BrCl + Br Br + ICl -* BrCl + I Br + IBr -* Br + I c1+ ICl -* c1 + I k/cm3 molecule-' s-' 3.0 If 1.5 x lo-" 1.0 & 0.2 x lo-" 1.45 f 0.20 x lo-'' 1.20 0.15 x lo-'' 8.0 1.0 x lo-', 3.0 & 0.8 x 3.5 & 0.6 x lo-" studied the emission from Br(5s4PS12) and Br(5s4P3,,) following the selective vacuum-u.v.photolysis of Br in a flow system using atomic emission photolytic sources. The quenching of the emission was investigated and collisional quench-ing cross-sections for the 4P5/2 state are reported (Table 21) and compared with Table 21 Rate data for the collisional deactivation of Br(5s4PSi2) Collision partner (M) Ar He *2 H2 Br* SF6 co k&m3 molecule- ' s- Qd8.' <2 10-13 c4.0 10-4 <2 x 10-13 < i s 10-4 5.0 x lo-'' 2.7 10-3 1.0 x lo-" 1.8 x 1.6 x lo-" 5.1 x lo-'' 1.46 1.0 x 10-'O 0.284 2.9 x lo-' Q JQ, 4 0 - 3 <5 x 10-4 6.7 x 10-3 3.6 x lo-, 5.8 x lo-, 2.5 0.38 the hard-sphere collision cross-sections (cc).The rate of quenching with in-dividual gases is somewhat more rapid than that observed hitherto by Donovan and H ~ s a i n " ~ for the lower spin-orbit state Br(42P1/2) but the trend with collision partners is similar. 1 9 3 M. A. A. Clyne J. A. Coxon and L. W. Townsend J.C.S. Faraday II 1972,68 2134. ' 9 4 M. A. A. Clyne and H. W. Cruse J.C.S. Faraday II 1972 68 1377. 19' P. P. Bernard and M. A. A. Clyne J.C.S. Faraday II 1972. 68 1758. R. J. Donovan and D. Husain Trans. Faraday SOC. 1966 62 2987 52 R. J. Donovan D. Husain and L. J. Kirsch Clyne and his c o - w ~ r k e r s ' ~ ~ have also studied the recombination of bromine atoms in a discharge flow system using optical absorption by Br, titration with CINO and measurement of the A 3n(l,) -+ X 'C,' emission intensity following the recombination kY* Br + Br + M * Br,[A 3n(l,)] + M (52) These authors have characterized recombination rate constants for formation of the A state with different third bodies (M) of k:r,2 = 8.7 4.4 x 10-34cm6 molecule-' s- ' kFy/k$ = 22 and kyz/k$; = 1.1.Activation energies of -9.6 & 3.0 and -7.9 f 3.0 kJ mol-' are reported for k:? and k$i respec-tively. Burns et a1,198*199 have carried out trajectory calculations on bromine-atom recombination which include the effects of radical complex formation, energy transfer and rigid-rotor relaxation. Ferguson and Whittle200 have described a competitive study of bromine-atom abstraction from fluoroalkyl bromides by photochemically generated bromine atoms. Chromatographic analysis of products was employed and relative-rate data are reported."' Deakin and Husain201,202 have extended their kinetic studies on 1(5'P,,,), involving time-resolved attenuation of atomic resonance radiation following flash photolysis to a detailed investigation of the effects of temperature on both physical relaxation and chemical reaction.The physical processes of spin-orbit relaxation to I (52P3,2) on collision were studied by these authors over a wide range of temperature (180-410 K) and the resulting Arrhenius rate data are presented in Table 22. Especially striking are the small negative temperature coefficients Table 22 collisional deactivation of 1(52 Pl12) by various molecules Arrhenius parameters and the mean transition probability (P) for the Quenching gas CH4 C2H6 C3H8 n-C4H 10 CH2=CH2 CH3-CH=CH2 CHECH D2 H2 N' 0, 12 log ,4/crn3 molecule- s -- 13.40 f 0.17 - 13.43 & 0.11 - 13.24 f 0.14 - 12.73 f 0.11 - 13.09 0.1 - 12.42 f 0.1 - 13.45 f 0.12 -15.56 f 0.01 - 11.65 f 0.14 -15.19 f 0.29 -10.45 & 0.18 - 13.41 f 0.67 E/kJ mol-' -2.1 f 0.8 -2.1 0.4 -2.9 f 0.4 - 1.3 f 0.4 -2.5 f 0.4 -0.4 f 0.4 -5.0 f 2.5 0.0 & 0.4 7.1 0.8 6.3 f 0.4 0.8 f 0.8 -13.8 f 4.6 P = AfZyibK 1.2 x 10-4 1.3 x 1 0 - ~ 2.0 x 10-4 7.2 x 10-4 2.9 x 10-4 1.3 10-3 1.2 x 10-4 2.3 x 10-3 1.3 x 10-7 2.2 x 10-4 5.2 x 1.2 x lo-' observed for a number of gases.These could equally be due to a temperature dependence of ca. T - in the pre-exponential factor.The relatively large 'negative 19' M. A. A. Clyne J. A. Coxon and A. R. Woon-Fat Faraday Discuss. Chem. SOC., 1972 No. 53 p. 82. 19* A. Gelb R. Kapral and G. Burns J . Chem. Phys. 1972 56,4631. A. G. Clark and G. Burns J . Chem. Phys. 1972,56,4636. * O 0 K. C. Ferguson and E. Whittle J.C.S. Faraday I 1972 68 64. J. J. Deakin and D. Husain J.C.S. Faraday II 1972 68 1603. '02 J. J. Deakin and D. Husain J . Photochem. 1973,1 353 Reactions of Atoms and Small Molecules 53 activation energy' for I (- 3.3 kcal mol- ') is in accord with the stability of I formed from ground-state atoms.203 The quenching data for N and CO cm3 molecule- s- 1 ,01 ( -3.3 yTkJ mol- ' p = 4.7 x 10-16 exp the latter having been determined by time-resolved emission in the i.r. 1(5P1/,) + I(5'P3,,) + hv(1.315 pm) are in quantitative accord with the theory of Andreev and Nikitin,,04 who postulate the production of d' = 3 following quenching by both these molecules.Arrhenius data for some chemical reactions of I(52P1/2), obtained by Deakin and Husain202 using this attenuation method are presented in Table 23. Table 23 Arrhenius parameters for chemical reactions of I(5 PI,,) with various molecules log, A/cm3 React ion molecule-'s-' E/kJ mol-' AHlkJ P= A/ZydbK 1(52P1,2) + c1 * IcI + c1 - 11.6 0.2 6.7 k 1.3 -59.8 1.0 x lo-' I(5'P1,,) + Br * IBr + Br - 10.4 k 0.2 1.7 & 1.3 -75.2 0.3 I(52p1,2) + IcI --+ 1 + c1 -10.8 0.1 0 -32.2 0.1 1(5'P1,,) + IBr -+ I + Br -10.7 & 0.3 0 -64.4 0.1 I(52p1,2) + NOCl -* ICI + NO -10.6 k 0.2 2.5 1.3 -141.3 0.2 Two groups of experiments on iodine-atom recombination may be mentioned, both involving photoelectric monitoring of the reappearance of I following flash photolysis.Ip and Burns205 have made an extensive study of the recombina-tion over a wide temperature range 300-1173 K for a number of third bodies. The recombination rate constants which have been determined with considerable accuracy are presented in an empirical form as a function of temperature. This work essentially supplements previous measurements by Blake and Burns.206 Troe et aL207 have employed conventional and giant-pulse laser photolysis to study the recombination of iodine atomsat total pressures of up to ca. 10o0 atm. They conclude that this method yields a separation of the contributions of the intermediate-complex and energy-transfer recombination mechanisms and that, in the limiting low-pressure range the energy-transfer mechanism accounts for ca.one-third of the overall recombination rate. The authors present limiting second-order rate constants at high pressure for recombination by each of these mechanisms namely, kgT = 3.3 & 1.7 x lO-l4cm3 molecule-' s-l and k;! = 3.3 & 0.3 x lo-" cm3 molecule-'s-' 20' N . Davidson in 'Fundamental data obtained from shock tube measurements' ed. A. '04 E. A. Andreev and E. E. Nikitin Theor. Chim. Acta 1970 17 171. ' O S J. K. K. Ip and G. Burns J . Chem. Phys. 1972,56 3155. ' 0 6 J. A. Blake and G. Burns J . Chem. Phys. 1971 54 1480. * 0 7 H. Hippler K. Luther and J. Troe Chem. Phys. Letters 1972 16 174.Ferri Agardograph KO. 41 Pergamon Press Oxford 1961 p. 138 54 Further the radical complex equilibrium R. J . Donovan D. Husain and L. J. Kirsch I + Ar 5 IAr (53) is found to be characterized by an equilibrium constant of K z 3 x 102cm3 mol-'. Broadbent and Callear"' have stu'died the quantum yields for the collisional dissociation process 12(B3110+,) + M -+ I(S2Pl,,) + I(5'P3,,) + M (54) (M = He or Ar) by means of steady-photolysis measurements. The results are discussed in relation to fluorescence-quenching measurements and non-equili-brium effects in the recombination of atoms. 3 Diatomic Species H2(a3 Eg+).-The collision-free lifetime of H2(a3 CB+ u' = 0) has been deter-mined as 26 f 2ns following observation of the U.V. continuum emission produced by high-energy electron impact on H2.'09 The cross-section for energy transfer to a state (tentatively identified as the log2pn'rI state) at resonance with the a 3Xg+ state was found to be (6 f 2) x 10- l4 cm' being -20 times larger than the gas kinetic collision cross-section.209 It was further shown that quenching of these coupled states to the ground state by molecular hydrogen has a cross-section of 4.8 x 10-'6cm2.This is in agreement with the measurement by Center (Center's value'" is based on an earlier measurement of the lifetime; however the value based on the above lifetime still gives reasonable agreement), although no account was taken of an intermediary state in this work.210 He2(3p311g).-Rotational relaxation of He2(3p3n,) has been monitored following optical pumping of the (2s3C,') state (formed in a flowing helium afterglow), with a tunable dye laser.'" Relaxation by ground-state He atoms via the AJ = 1 channel was found to have a large rate coefficient -2 x lo-" cm3 molecule-'^-^ contrary to expectations from first-order theory.The AJ = 1 channel accounts for about half of the total relaxation rate for the 3 = 8 state of He2(3p3ng u' = 0). Ar,(4~'*~ Xu+) and Kr,(5~'*~ Xu+).-Energy transfer from these excited states to ground-state Xe and from Ar2(4s'93Zu+) to ground-state Kr has been in-vestigated.' '' The well-known vacuum-u.v. emission continua which arise from these states were monitored (radiative lifetimes for the upper states - s); however it was not possible to distinguish between the 'singlet' and 'triplet' state decay rates.The total cross-sections for relaxation of both states were found to be large (- 10- l 4 cm') and a theory involving long-range dipole-dipole 'On T. W. Broadbent and A. B. Callear J.C.S. Faraday II 1972,68 1367. ' 0 9 R. T. Thompson and R. G. Fowler J . Quant. Spectroscopy Radiative Transfer 1972, 12 117. ' I o R. E. Center J . Chem. Phys. 1971,54 3499. 2 1 1 C. B. Collins and B. W. Johnson J . Chem. Phys. 1972,57 5317. ' 1 2 A. Gedanken J. Jortner B. Razard and A. Szoke J . Chem. Phys. 1972 57 3456 Reactions of Atoms and Small Molecules 55 coupling was proposed to account for the The results were also compared with similar data on the relaxation of excited noble-gas atoms and it was shown that while the excited atoms undergo near-resonant transfer the excited molecules tend to populate the lowest excited states of the quenching atom provided these lie in the same energy range as the molecular continuum e.g.CH(A*A).-Rotational relaxation of CH(A2A) produced by the pulse radiolysis of CH and C2H has been monitored via the emission CH(A2A+ X 211).213 Fluorescence from the A2A and B2C states of CH (and from excited states of CH, and the H atom) has been observed following vacuum-u.v. photolysis (55.5-124.2 nm) of CH4.214 Absolute cross-sections for a number of photodissociation channels were determined.2 CN.-Further work on the reactions of CN(X2C) produced via the pulse radiolysis of cyanogen in the presence of argon has been reported.,' The rate constant for reaction with 0 was given as 1.1 x lo-'' cm' molecule-' s-' in agreement with previous On the basis of studies at two temperatures (300 and 377 K) it was tentatively suggested that reaction with 0 had a small negative activation energy.However it was also shown that the total rate for removal of CN in the presence of 0 increases with vibrational energy content of CN (the rates for v" = 0 2 and 4 were presented and showed a systematic increase in rate with increasing vibrational energy) contrary to previous work.2' The formation of the product NCO was also monitored and the rate shown to be faster than the decay of CN(X ,X v" = 0) strongly suggesting that vibrationally excited CN radicals contribute to the formation of NCO. Thus the reaction appears to have a positive activation energy with respect to vibrational This was rationalized in terms of a 'collision complex' NC-0-0 with vibra-tional energy assisting the fracture of the 0-0 bond as the complex forms products.Quite how this can be reconciled with an overall negative activation energy is not clear. The reaction of CN with C,N2 was also studied; however the rate data presented2" (log k = - 12.03 - [13.l(kJ mol-')/2.3 RT]) are only in moderate agreement with previous work.,' Curvature in kinetic plots (attributed partly to vibrational relaxation of CN) and changes in reaction order with concentration of CN were observed and thus further work will be required to characterize fully the reactions involved.21 Work on the reactions of CN with alkanes has been extended' l 7 and Arrhenius parameters have been presented for reaction with methane and ethane {log kCHs = - 10.67 - [8& & 0.8 (kJ mol- ')/2.3 RT] ; log kCZH6 = - 10.61 E x 0).The activation energy for reaction with methane therefore lies between those for ' 1 3 M. Clerc and M. Schmidt Faraday Discuss. Chern. SOC. 1972 no. 53 p. 217. 'I4 A. R. Welch and D. L. Judge J . Chem. Phys. 1972,57,286. 'I5 G. E. Bullock and R. Cooper J.C.S. Faraday I 1972,68 2175. 'I6 J. C. Boden and B. A. Thrush Proc. Roy. SOC. 1968 A305 107. '" G. E. Bullock and R. Cooper J.C.S. Faraday I 1972,68 2185 56 R. J . Donovan D. Husain and L. J. Kirsch chlorine- and fluorine-atom reactions. It should be pointed out however that these Arrhenius parameters" ' conflict with previous relative rate data and with the work of Boden and Thrush.216 The rate constants for reaction of CN with propane and CD, a t 300K were also determined [kCJHs = (5.3 & 0.8) x lo-'' cm3 molecule- ' s- ' ; kCD4 = (4.0 f 0.6) x lo-' cm3 molecule-' s-'; this latter value refers to reaction for u'' = 01.The rate constant for CD is thus approximately half of that observed for CH at 300K and demonstrates the importance of a relatively large tunnelling effect. The removal of vibrationally excited CN(v" = 4) by CD was found to be significantly faster than CN(u" = 0) [k = (5.8 0.3) x lo-' cm3 molecule- ' s-'I. This supports the data for CH,, where a similar but less significant effect was observed. It should be emphasized, however that the increased rate of removal for vibrationally excited CN was attributed to physical relaxation effects,'17 and not increased reactivity as observed for 0 .' The reaction of CN with NH has also been reinvestigated,"' CN + NH -% HCN + NH (56) The decay of CN and the formation of NH were monitored photoelectrically, the rates being in agreement within the experimental error. The rate constant k was determined as 2.1 x lo-" cm3 molecule-' s - l at 300 K and as 1.8 x 10- '' cm3 molecule- ' s- ' at 375 K indicating a small negative activation energy.218 The results are shown to be in agreement with previous flow-tube work.,' Faster removal of CN(u" = 4) relative to CN(d' = 0) was attributed to vibrational relaxation by NH, and a small negative temperature dependence for relaxation similar to that observed for quenching of vibrationally excited NO and CO was reported."' Rotational relaxation of CN(B 'Z +) formed by dissociative energy transfer from metastable argon atoms to CNBr has been studied and it was shown that relaxation by ground-state argon involved multiquantum transitions.Cook and have measured the lifetimes of CN(A 'll uf = lo) z A = 137 & 45 ns, and CN(B ,C u' = 0) zB = 39.4 9.3 ns from an analysis of the zero electric field limit linewidth of the level anticrossing spectrum. The lifetime of the B state was found to be in reasonable agreement with the most recent phase-shift measure-ments and that for the A state was in essential agreement with a value previously determined by microwave intensity measurements on the perturbed u' = 10 level. The lifetime of CN(A 211 u' = 10) is therefore almost two orders of magni-tude shorter than for the u' = 1-3 states.'" Further work on the excitation of the CN(B 'Z+ --* X 'Z+) violet emission in active nitrogen supports the earlier proposal that the B state is formed by energy transfer from vibrationally excited Nz molecules.1 0 5 7 2 2 En ergy transfer from N2(A ,CU+) to radiative levels of CN was shown to be of minor imp~rtance."~ 2 1 8 G. E. Bullock R. Cooper S. Gordon and W. A. Mulac J . Phys. Chem. 1972 76, 2 1 9 W. H. Duewer J. A. Coxon and D. W. Setser J . Chem. Phys. 1972,56 4355. 2 2 0 T. J. Cook and D. H. Levy J. Chem. Phys. 1972 57 5059. 2 2 1 G. M. Provencher and D. J. McKenney Chem. Phys. Letters 1971 10 365. 1931 Reactions of Atoms and Small Molecules 57 Quenching of the CN(B ,Cf + X ,C+) fluorescence (produced by vacuum-U.V.photolysis of ICN) has been studied for the collision partners CH, H, Kr, Ar and ICN.,, The variation in cross-section for quenching by ICN was studied as a function of relative collision velocity and found to be constant. C0.-The observation of stimulated emission (181-197nm) on Q- and R-branch lines of the CO fourth positive system ( A 'lT+ X 'C) should generate considerable interest in the A state.223 Optical excitation of CO(A 'lT) leading to resonance fluorescence has been used to obtain rate data for quenching of the u' = 0 and u' = 1 levels by He Ne Ar Kr H, D, and N,.224 Large cross-sections with values approaching gas-kinetic were observed. Further data are given by Shackleford et al. l 7 The rotational dependence of the lifetime of CO(a31T) has been investigated using a time-of-flight technique., The results were compared with those predicted by theory226,227 and show that rotational-level lifetimes vary from 3 ms to several hundred ms.The rotationally averaged lifetime (for a Boltzmann distribution at 4500 K) has been given228 as (70 & 4.0) x CO(a311) is formed by dissociative recombination of CO,+ and has been studied in a flowing He afterglow.228 The forbidden emission via the Cameron bands CO(a31T + X ' 2 ) has been employed to measure quenching rates by CO, N NO and He (Table 24). Emission from the A and B states of NO was s. Table 24 Quenching data for CO(a311) Quenching species 10' 'k/cm3 molecule- s- ' co2 N2 NO He < 10- l4 4.8 k 2.4 (u' = 0 4 ) 3.8 k 1.8 (u' = 0) 7.3 k 3.6 (u' = 1 4 ) 32 f 16 (u' = 0 4 ) observed following quenching of CO(a 311) and emission yields were estimated as ( A x 8 %; B x 2 %).228 Transfer to N,(A '2) is possible from CO(a311 u' = 1) but not from the u' = 0 level and accounts for the increased rate of relaxation for the levels u' = 1 - 4 .The CO(d3A) and (d3C) states are also populated228 by dissociative recombination of CO +. CO(a31T) is also formed by vacuum-u.v. photolysis of CO (109-85 nm).229 The emission yield from CO(a311 + X 'C) rises smoothly from a zero value at 109 nm to -60 % at 90 nm and indicates that the surface crossings leading to CO(a311) lie outside the Franck-Condon region for the initial excitation.229 2 2 2 W. M. Jackson and J.L. Faris J . Chem. Phys. 1972,56,95. 2 2 3 R. T. Hodgson J . Chem. Phys. 1972 55 5378. 2 2 4 F. J. Comes and E. H. Fink Chem. Phys. Letters 1972 14 433. 2 2 5 C. E. Johnson and R. S. Van Dyck J . Chem. Phys. 1972,56 1506. 2 2 6 T. C. James J . Chem. Phys. 1971 55 4118. 2 2 7 T. C. James personal communication in ref. 225. 2 2 8 T. S. Wauchop and H. P. Broida J . Chem. Phys. 1972 56 330. 2 2 9 G. M. Lawrence J . Chem. Phys. 1972 56 3435 58 R. J. Donovan D. Husain and L. J. Kirsch C§.-The radiative lifetime of CS(a3 n) formed by the dissociative excitation reaction between Ar(43P,)and CS has been measured using flow-tube techniques (z x 3 x s).,~' Quenching of CS(a311) by CS and Ar were also studied. A more detailed spectroscopic investigation of the emission a311+ X IC+, analogous to the CO Cameron bands has been reported.231 Fluorescence from CS(A 'IJ -+ X 'C) has been observed following the vacuum-U.V.photolysis of CS .232 The spin-forbidden nature of the overall process cs2 5 CS(A 'n) + s(33P2) (57) was accounted for in terms of predissociation from the initially populated Rydberg states of CS . CSe.-The formation of CSe following the flash photolysis of CSe with light restricted to A > 320nm (for which direct photodissociation is energetically impossible) has been attributed to the reactions173 and 2 CSe,* -+ 2 CSe + Se, (59) which is similar to the mechanism previously proposed to explain analogous results with CS,. The formation of Se simultaneously with CSe appears to rule out an alternative mechanism involving absorption of a second photon by CSe,*.The reaction of oxygen atoms produced by photolysis of NO, with CSe, was also shown ' to produce CSe via o + CS~ * SeO + CSe (60) By monitoring the growth of CSe a lower limit for k60 of > 2 x cm3 molecule- s- ' was estimated. The SeO radical was not observed ; however, SeO formed via SeO + NO -+ SeO + NO (61) was observed and an approximate value for k6 given as k6 x 1.5 x 10- cm3 molecule- ' s- I estimated from the rate of growth of SeO .' 7 3 The NO + CSe, system is thus similar to the NO + CS system. Furthermore laser action resulting from the reaction 0 + CSe + Cot + Se (where Cot represents vibrationally excited CO molecules) has been observed.23 (62) 230 L. G. Piper W. C. Richardson G.W. Taylor and D. W. Setser Faraday Discuss. 2 3 1 G. W. Taylor D. W. Setser and J. A. Coxon J . Mol. Spectroscopy 1972 44 108. 232 H. Okabe J . Chem. Phys. 1972,56,4381. 233 1. W. M. Smith and C. Wittig Appl. Phys. Letters 1972 21 536. Chem. SOC. 1972 no. 53 p. 100 Reactions of Atoms and Small Molecules 59 NH.-Previous work on the reactions of NH(X3C) produced in the pulse radiolysis of NH and monitored via the A ,lI + X 3C transition (336.0 nm),234 has been extended to include reaction with NO(kN,+No = 3.8 x lo-" cm3 molecule- ' s- 1).235 N,.-Energy transfer from N,(A C,') to mercury atoms to yield Hg(6,P,) has been studied in a flow system:72 The value determined for k63 [(3.4 f 1.0) x lo-'' cm3 molecule-' s- '3 is in agreement with the value given by Callear and and strongly suggests that earlier work in which the mercury concentration was not monitored gave values which were too low.Rate data for quenching of N,(A ,Z,,+) by NH, SO,, C,N, CH,CN CH,OH CO (0'' = 0 and u" = l) N,O O H, CO, CH,, and NO have been given and are compared with previous data.236 Most of the data are in agreement where overlap occurs. N,(A3Z,+) has also been ob-served' Freund has presented a model calculation on the intrasystem cascading between the a'n, a' 'Xu- and wlAu states of N, and has resolved a number of apparently conflicting reports on the lifetime of the a'n state.238 Energy transfer from N,(a'll,) to CO to yield CO(A 'll) has been investigated in detail and the vibrational dependence of this process e s t a b l i ~ h e d .~ ~ ~ ~ ~ ' Quench-ing of N,(B313,) to N2(u'rIg) by ground-state nitrogen atoms has been ob-served;241 emission from N,(B' ,Xu-) has also been observed and the B 31-Ig state identified as the precursor.242 The mechanism for the recombination of N atoms into excited states of N continues to be a controversial problem. 107,243*244 Rate coefficients for the relaxation of vibrationally excited N (0'' = 1) by O(z3PJ) [k = (3.5 & 1.4) x loei5 cm3 molecule- ' s-'I CO [k = (2 & 1) x lo-' cm3 molecule-' s-'1 and N,O [ k = (9 f 4) x 1O-l4cm3 molecule-' s- '3 have been measured using a photoionization techniq~e.'~',~~' Relaxation by CO and N,O proceeds by near-resonant vibrational exchange."' Nikitin has presented a theoretical treatment for the vibrational relaxation of N by oxygen atoms together with a number of other interesting atom + diatom systems.The theory shows agreement with the experimental results within an order of magnitude.246 The theoretical treatment by Fisher and B a ~ e r ' ~ ~ is also relevant to these data. 23* G. M. Meaburn and S. Gordon J . Phys. Chem. 1968,72 1592. 235 S. Gordon W. Mulac and P. Nangia J . Phys. Chem. 1971,75 2087. 236 J. A. Meyer D. W. Setser and W. G. Clark J . Phys. Chem. 1972 76 1. "' 238 R. S. Freund J . Chem. Phys. 1972 56 4344. 2 3 9 ' * O 2 4 1 2 4 2 2 4 3 M. F. Golde and B. A. Thrush Faraday Discuss. Chem. SOC. 1972 no. 5 3 p. 52. '** See also the general discussion following refs. 107 and 243. 2 4 s R. J. McNeal M. E. Whitson and G. R. Cook J . Chem. Phys.1972,57,4752. 246 E. E. Nikitin and S. Ya. Umanski Faraday Discuss. Chem. SOC. 1972 no. 53 p. 7. N,(A 3Cu+) + Hg(6'So) -% N,(X 'Cg+) + Hg(63P1) (63) directly ; however kinetic studies have not been made. Personal communication in ref. 236. M. F. Golde and B. A. Thrush Proc. Roy. SOC. 1972 A330,97. M. F. Golde and B. A. Thrush Proc. Roy. SOC. 1972 A330 109. M. F. Golde and B. A. Thrush Proc. Roy. SOC. 1972 A330.79. M. F. Golde and B. A. Thrush Proc. Roy. SOC. 1972 A330 121 60 R. J. Donovan D. Husain and L. J. Kirsch N,+.-The direct observation of N2’(X2 Zgf u” = 0) using kinetic absorption spectroscopy with pulse radiolysis has been reported.2474 The decay of N2+ was observed to be third order up to pressures of 160Torr although slight curvature in a plot of the second-order rate coefficients against pressure of N, could be observed from the data presented and suggests that the reaction to yield N,+ is in the fall-off region.The reactions of N,’ with Xe O, CO NO, H, H,O NH, CH, C,H, buta-1,3-diene and cyclopropane (charge transfer being dominant in many cases) were also and demonstrate that this is a useful technique for obtaining total cross-sections for ion-molecule reactions. NO.-Vibrational relaxation of NO(X2 n 0’’ = 2 and v” = 1) has been in-vestigated using a sensitive ‘split beam’ kinetic spectroph~tometer.~~~~ The vibrationally excited nitric oxide was formed via the reaction between O(2’0,) and N,O the yield of vibrational energy being -20% of the total available energy. Vibrational relaxation by N,O CH, and Ar was investigated and it was shown that the rate for vibrational exchange with N,O decreased with vibrational quantum number owing to the increasing energy discrepancy.The quenching and enhancement of NO /3-emission by N(2,S)and 0(23PJ) has been discussed.247c OH.-An excellent review of gas-phase reactions involving the hydroxyl radical has been given by Drysdale and Lloyd.248 A second more recent review has been given by Wilson,249 with emphasis on reactions involving CO H CH,, and self-disproportionat ion. Resonance fluorescence (A ,C+ u’ = O-+ X ,lI D” = 0) has been used to monitor the reactions of OH(X ’n) with H, D, and C0.250 The OH radicals were produced by vacuum-u.v. photolysis of H,O and concentrations as low as 10” molecules cmb3 could be detected thus reducing the possibility of radical-radical side-reactions.Rate data at 298 K were determined as (overall uncertainty OH + co a CO + H (k64 = 1.35 x 10-13 cm3 molecule-’ s-1) (64) It 15 %), OH + H H,O + H (k65 = 7.1 x 10-15 cm3 molecule-’ s-1) (65) OH + D -% HDO + D (k66 = 2.05 X lo-’’ cm3 molecule-’ S - l ) (66) A brief review of previous work on these reactions was given together with an extensive table of previous data. The resonance fluorescence technique gives values for the above rate constants which are in very close agreement with the results of Greiner (reviewed last year) and with most of the other direct deter-minations.* 5 0 2 4 7 ( a ) J. W. Dreyer and D. Perner Chem. Phys. Letters 1971,12,299; (b) C. R. Boxall and J. P. Simons Proc.Roy. SOC. 1972 A328 515; (c) I. M. Campbell and S. B. Neal, Faraday Discuss. Chem. SOC. 1972 no. 53 p. 72. 14’ D. D. Drysdale and A. C. Lloyd Oxidation and Combustion Rev. 1970 4 157. 249 W. E. Wilson J . Phys. and Chem. Ref. Data 1972 1,535. 1 5 0 F. Stuhl and H. Niki J. Chem. Phys. 1972 57 3671 Reactions of Atoms and Small Molecules 61 Reactions of OH with the oxides of nitrogen have received considerable atten-tion and their importance in atmospheric reactions has been empha~ized.~’ 1-254 The reaction OH +NO + M -% HONO + M (67) has been studied by a number of techniques including resonance fluores-cence,251*252 resonance absorption,253 and e.s.r. ;”‘ rate data for this reaction are collected in Table 25. Morley and Smith253 studied reaction (67) using flash Table 25 Rate data for the reaction OH + NO + M + HNO + M k/cm6 molecule-2 s-(4.1 & 0.6) x (1.9 & 0.3) x 3.3 x 10-3’ 5.6 10-31 T/K 300 416 273 298 397 297 300 300 M He He Torr) Ar (8 Torr) He (30 Torr) He (5 Torr) Comments Re$ 253 He was added to gas mixtures to yield a total pressure of 30 Torr Studied over the pressure range 1 254 0.5-5 Torr Preliminary 1 252 values Rate constants taken from graph in ref.251 at 30Torr 251 Data are pre-sented for the range 5-82 Torr and a high-pressure limiting value of k = (2 k 1) x 10-l2 cm3 molecule-s-’ was given H was shown to be 2.3 k 0.9 times more efficient than He as third body. photolysis and resonance absorption techniques. Hydroxyl radicals were produced by flash-photolysing NO + H mixtures : NO NO + 0(210,) (68) (69) 0 ( 2 ’ D ) + H + OH + H H + NO _* OH + NO 2 5 2 5 2 F.Kaufman and J. C. Anderson Chem. Phys. Letters 1972 16 375. 2 5 3 C. MorleyandI. W. M. Smith J.C.S. Furaduy ZI 1972,68 1016. 2 5 4 A. A. Westenberg and N. De H a s J . Chem. Phys. 1972,57 5375. F. Stuhl and H. Niki J . Chem. Phys. 1972 57 3677 62 R. J. Donovan D. Husain and L. J. Kirsch The technique proved to be very sensitive and concentrations of OH of less than lo1 molecules cm- were used. Reaction (67) was assumed to be in its third-order region (total pressure 30Torr) by comparison with data on reaction (71) and k67 given as (4.1 f 0.6) x cm6 molecule-2 s-’ (300 K).253 The smaller value for k, observed at 416 K demonstrates that the reaction has a ‘negative activation energy’ as expected [ x - 6.7 (& 2.0) kJ mol- The data of Westen-berg and De H ~ s s ~ ~ obtained using a fast-flow reactor and e.s.r.detection of OH (OH produced via H + NO,* OH + NO) show a similar temperature dependence (Table 25)’ but differ by a factor of two from the data of Morley and Smith indicating that reaction (67) is not in its third-order region at 30Torr (He) as assumed. This point is confirmed by the work of Stuhl and Niki,251 who employed the resonance fluorescence technique to follow the reaction over the pressure range 5-82Torr. The data of Morley et al.253 and Westenberg et al.254 are thus seen to be in agreement within experimental error. The e.s.r. data254 also show Ar to be less efficient than He as third body and thus indicate that the preliminary results of Kaufinan and Anderson252 are in agreement with the other rate data for reaction (67).The only anomalous feature in these kinetic studies appears to be the observation with the e.s.r. technique that reaction (67) becomes pressure-independent above 3 T ~ r r . ~ ~ The reaction OH +NO + M HNO + M (71) has also been studied by resonance absorption, 53 resonance fl~orescence,~ 5 2 and e.~.r.,’~ techniques. The data are collected in Table 26. Morley and Smith253 Table 26 Rate data for the reaction OH + NO + M -+ HNO + M k/cm6 molecule-2 s- T / K M Comments Ref } 252 (1.0 0.3) x 10-30 297 Ar (3 Torr) Data given for (2.0 0.5) 10-30 297 N (8 Torr) the range 0.5-10 Torr 2.0 x 10-30 273 He Studied over 1.6 x 10-30 298 He the range } 254 5.8 10-31 395 He 0.5-5 Torr (I Data are presented253 over the pressure range 20-300 Torr and for temperatures of 300 and 416 K.studied the reaction over the pressure range 20-300 Torr and at temperatures of 300 and 416 K. In this pressure range the reaction was clearly observed to be in the transition region between second- and third-order kinetics. Unfortunately, the high-pressure limit was not accessible; however the variation of the rate with total pressure was compared with the behaviour predicted by RRKM theory.253 The e . ~ . r . ~ ~ data show that Ar is a factor of two less efficient than He as a third body in reaction (71) and are thus in agreement (for p < 3 Torr) with the data of Kaufman and Anderson.252 The rate constant for reaction (71) also shows a negative temperature coefficient as expected.Reactions of Atoms and Small Molecules The reactions 63 OH + HN03 -& H,O + NO3 0 + HNO -% OH + NO, (72) (73) were also investigated and k72 was determined as (1.3 & 0.5) x lo-' cm3 mole-cule-' s- at 300 K. The rate constant k, was found to be < 1.3 x cm3 molecule- ' s-' at this temperat~re.'~~ Hydroxyl radicals have also been observed in absorption following the reaction of hot hydrogen atoms with CO 2 5 5 H + CO -+ OH + CO AH = 102kJmol-' (74) It was shown that only a small proportion (- 10 %) of the hot atoms lead to OH formation the major process being loss of kinetic energy on collision with CO . Overtone emission from the U" = 9 level of OH(X ,lI) produced via the reaction of H atoms with O, has been utilized to monitor the reactions of this vibrationally excited state with 0,.256 The mean radiative lifetime for U" = 9 [r = (6.4 & 1.4) x lo- s] and the rates for vibrational relaxation by the quenching gases 0, N, NO N,O CH, CO, SO, H2S or H,O have been given.2579258 The rates for reaction of levels U" = 2-9 with ozone have also been examined.," Chemiluminescence resulting from the reaction of 0 with a number of small olefins and with acetaldehyde has been shown to arise (in part) from the forma-tion of vibrationally excited OH radicals.,,' SH.-The formation and decay of SH radicals following the flash photo-dissociation of H,S has been re-inve~tigated.~~~ It was proposed that the reaction S + SH + S + H AH = -8lkJmol-' (75) is rapid and that the rate-determining step for removal of SH under the conditions used was either H + SH -% H + S AH = -92kJmol-' (76) or SH + SH -% H,S + S AH = -43kJmol-' (77) where k, = 1 x lo-'' or k, = 3 x lo-'' cm3 molecule-'s-'.H,S has been monitored in time-resolved experiments.261 2 5 6 A. E. Potter R. N. Calthorp and S. D. Worley J . Chem. Phys. 1971,54 992. 2 s 7 A. E. Potter R. N. Calthorp and S. D. Worley J . Chem. Phys. 1971,55 2608. 2 s 8 A. E. Potter R. N. Calthorp and S. D. Worley J . Phys. Chem. 1972,76 151 1. 2 5 9 A. E. Potter R. N. Calthorp and S. D. Worley Appl. Optics 1971 10 1786. 2 6 0 B. J. Finlayson J. N. Pitts and H. Akimoto Chem. Phys. Letters 1972 12 495. 2 6 1 Fluorescence from SH(A 2Z+ U' = 0) formed in the vacuum-u.v.photolysis of Values for the 5 5 R. B. Langford and G. A. Oldershaw J.C.S. Furuduy 11 1972,68 1550. K. H. Becker and D. Haaks J . Photochem. 1972.1 177 64 R. J. Donovan D. Husain and L. J . Kirsch radiative lifetime [ z ~ ~ = (0.55 & 0.14) x lop6 s ; T~, = (0.37 & 0.07) x s] and cross-sections for electronic quenching by H,S D,S H N He Ar or Ne, are reported. Cross-sections for quenching of SH by H,S and SD by D,S (-200 x 10- l6 cm2) indicate that long-range resonant transfer is involved ; cross-sections for the other gases are very much smaller (0.1 x 10- l 6 cm2).261 The oscillator strength for the transition SH(A ,C+ u' = 0- X ,II u" = 0) was calculated as foo = (1.45 k 0.4) x lo- [foo(SD) = (2.2 k 0.4) x 10-3].261 HSe and me.-Vacuum-u.v.spectra of these transient species have been observed following the isothermal flash photolysis of H,Se and H,Te.262 A number of new Rydberg transitions were reported and values for the ionization potentials given as I.P.(HSe) = 9.8 eV and I.P.(HTe) = 9.1 eV. The kinetics for the formation and decay of HSe and HTe were not investigated. However it was noted that electronically excited HTe ( X ,111,,) was formed ;262 spin-orbit relaxation of this state to the ground-state HTe(X ,II3/2) should be of interest as HTe is isoelectronic with the iodine atom. However unlike the iodine atom, it is now possible for the electronic energy to be partitioned between vibration and rotation states during collisions with monatomic quenching partners.0 2 ( X 3 C,-).-The vibrational relaxation of 0 formed by flash photolysis of 0, in levels u" = 9-14 has been monitored uia the Schumann-Runge ~ y s t e r n . ' ~ ~ ~ ~ ~ Relaxation by OQ3P,) was shown to be efficient and the results strongly suggest that multiquantum transitions are important.' 43*263 O,(db,).-A large number of new absorption bands arising from 02(u'Ag) have been observed in the vacuum ultraviolet following the flash photolysis of 0 in the presence of He.264 Over twenty new electronic states (Rydberg) of 0 have thus been located and Rydberg series leading to the first ionization potential identified. This new spectrum was further used to examine quenching of O,(u'Ag) by the gases He Ar Kr Xe N, H, and CO (Table 27).264-274 The rate constant for reaction with 0 was also determined264 as (4.4 f.1.3) x 10- ' cm3 molecule- s- ' (300 K). The Arrhenius parameters for reaction with O3 have been reported by several workers and there is now general agreement over their v a l ~ e s . ~ ~ ~ ~ ~ ~ Us ing labelled oxygen Jones and B a y e ~ ~ ~ have shown that '" R. J. Donovan D . J. Little and J. Konstantatos J.C.S. Faraday 11 1972 68 1812. 263 H. Webster and E. J. Bair J . Chem. Phys. 1972,56 6104. 264 R. J. Collins D . Husain and R. J. Donovan J.C.S. Faraduy 11 1973 69 145. 2 6 5 K. H. Becker W. Groth and U. Schurath Chem. Phys. Letters 1971 8 259. 2 6 6 F. D. Findlay and D. R. Snelling J . Chem. Phys. 1971 55 545. 2 6 7 R. P. Wayne d d v . Photochem. 1969,7 31 1 . 2 6 8 I. D. Clark and R.P. Wayne Chem. Phys. Letters 1969 3 405. 269 I. D. Clark and R. P. Wayne Proc. Roy. SOC. 1969 A314 1 1 1 . 2 7 0 K. H. Becker W. Groth and U. Schurath Chem. Phys. Letters 1972 14 489. 2 7 1 "' I. D. Clark I. T. N. Jones and R. P. Wayne Proc. Roy. SOC. 1970 A317 407. 2 7 2 7 4 W. H. Breckenridge and T. A. Miller J . Chem. Phys. 1972 56 465. 2 7 5 W. Groth and R. P. Wayne Faraday Discuss. Chem. SOC. 1972 no. 53 p. 232. 276 I. T. N. Jones and K. D. Baynes J . Chem. Phys. 1972,57 1003. F. D. Findlay and D . R. Snelling J . Chem. Phys. 1971 54 2750. F. D. Findlay C. J. Fortin and D. R. Snelling Chem. Phys. Letters 1969 3 204 Reactions of Atoms and Small Molecules Table 27 Rate constant (k,)for the collisional quenching of02(a1A,) at 300 K 65 Quenching gas He Ar Kr Xe 0 3 N2 H2 co k,/cm3 molecule- s - ' < 10-20 8.0 f 2.6 x < 8 x lop2' 9.0 f 1.2 x < 8 x < 7.9 * 5.4 x 3.4 f 0.9 x < 2 10-19 4.4 1.3 x 10-15 4.4 10-15 3.8 x 10-15 3.5 1.0 10-15 ~ 1 .1 x 10-19 < 10-20 1.4 k 0.2 x < 3 x 5.3 _+ 0.9 x lo-'* 4.53 k 0.19 x lo-" 3.7 f 0.3 x lo-'* <3.3 x 10-l6 <7 x 10-17 Method" v. u. v. a.e. i.r.a.e. i.r.a.e. i. r.a. e. a.e. i.r.a.e. k.p.i. V.U.V. V.U.V. V.U.V. V.U.V. a. e. i.r.a.e.b k.p.i.' k.p.i. a.e. i.r.a.e. i. r. a.e. i.r.a.e. a.c. i.r.a.e. e.p.r. V.U. v. V.U.V. V.U.V. Ref: 264 26 5 266 264 266 265 264 264 264 270 27 1 267,272 264 268,269 26 5 273 264 266 265 264 274 267-269 v.u.v.kinetic spectroscopy in the vacuum ultraviolet; a.e. atmospheric band emission following energy pooling ; i.r.a.e. infrared atmospheric band emission ; k.p.i. kinetic photoionization. Rate constant determined as a function of temperature. resonant energy transfer from 02(a'A,) to another oxygen molecule is extremely efficient. An important paper by Merkel and K e a r n ~ ~ ~ ~ on the quenching of 02(a1Ag) has recently appeared and although the experimental results were obtained from studies in solution they will certainly be relevant to gas-phase studies and the theoretical treatment given should be of fundamental importance. The efficiencies for quenching by the various solvents studied showed marked differences (H20 was - 300 times more efficient than CCl,).Furthermore marked differences between deuteriated and non-deuteriated solvents were observed H,O being ten times more efficient than D,0.277 According to the theory developed by Merkel and K e a r n ~ ~ ~ the electronic energy is coupled to the vibrational degrees of freedom in the quenching molecule and thus the quenching efficiency is related to the intensities of infrared overtone and combination bands of the quenching molecule in the energy regions appropriate for the transitions O,(a'A,)-+ O,(X 3Cg- u" = n) (with n = 0 being dominant in most cases). The theory was also extended to include quenching of 0 2 ( b 1 Z + ) and gave results in quantitative agreement277 with gas-phase experimental data. However, 2 7 7 P. B. Merkel and D. R. Kearns J .Amer. Chem. SOC. 1972,94 7244 66 R. J. Donovan D. Husain and L. J. Kirsch quenching of O,(a'A,) by amines and species with low ionization potentials may occur via a mechanism involving charge transfer and is thus not expected to follow the predictions made by the above theory. The rate data for quenching of O,(a'A,) by aliphatic amines have recently been revised in view of the realization that even very low concentrations of atomic oxygen in a flow system may lead to erroneous rate data278 (0 atoms were reduced to very low concentration levels by titration with NO,). Similarly the rate constant for quenching by tetra-methylethylene has been revised.," An increase in the rate coefficient at low pressures for quenching of O2(a1A,) by TME has been attributed to redissocia-tion of the initially formed addition adduct.280 It would appear that the presence of oxygen atoms might also account for these results (the data of Ogryzlo et ~ 1 .~ " show a decrease in rate coefficient with decreasing pressure; however if 0 atoms are not rigorously excluded the system is expected to be complex). Efficient relaxation of O,(a'A,) by the triplet states of quinoxaline and naph-thalene has also been reported.281 Direct excitation of the ' A state via the forbidden (a'A + X 'Z,-) transition has been achieved using the output from a Nd-YAG laser;282 however pressures of 130atm were required to obtain sufficient light absorption. The excitation of I by singlet oxygen has received further detailed study and a number of rate constants for energy transfer between these species and iodine atoms have been e s t a b l i ~ h e d .~ ~ ~ ~ ~ ~ Th e strong chemiluminescence observed from this system has been shown to arise from the stepwise excitation I,(X 1zg+) + o,(m,+) -+ I,[A 3n(i,)l + o,(x 3 ~ - ) (78) with the first process also producing atomic iodine. This work also demonstrates that resonant energy-transfer processes may be several orders of magnitude faster than analogous but non-resonant spin-allowed processes. Thus the process (80) 02(a1Ag) + I(5,P3,,) -+ I(52P1,2) + O,(X 'Xg-) 02(a'Ag) + I(52P,p) -+ 1(s2P3/,) + O,(X 3Zg-) is more than 5 x 10 times faster than the non-resonant (81) Similarly the energy transfer reaction I,[B 3n(0,+)] + O,(X 'X,-) -+ I,(X 'Cg+) + 0 2 ( ' A g 'C,+?) (82) has been shown to be highly inefficient (experiments carried out in hydrocarbon 278 K.Furukawa and E. A. Ogryzlo J . Photochem. 1972 1 163. 2 7 9 K. Furukawa and E. A. Ogryzlo Chem. Phys. Letters 1971 12 370. 2 8 0 R. A. Ackerman J. N. Pitts and R. P. Steer Chem. Phys. Letters 1972 12 526. 2 8 1 C. K. Duncan and D. R. Kearns Chem. Phys. Letters 1971 12 306. 2 8 2 I. B. C. Matheson and J. Lee Chem. Phys. Letters 1972 14 350; ibid. 1970 7 475. 283 R. G. Derwent and B. A. Thrush J.C.S. Faraday I I 1972,68 720. 284 R. G. Derwent and B. A. Thrush Faraday Discuss. Chem. SOC. 1972 no. 53 p. 162. 2 8 5 J. Olmsted and G . Koral J . Amer. Chem. SOC. 1972 94 3305 Reactions of Atoms and Small Molecules 67 solution). The absorption of U.V. radiation leading to the simultaneous excitation of O,(a'A,) and the lowest triplet state of several aromatic hydrocarbons has been observed286 (solutions containing the aromatic hydrocarbon and oxygen under pressure were used).The reaction of hydrogen atoms with O,(a'A,), H(l2S1,,) + O,(ulAg) -+ OH(X 'll) + O(23PJ) (83) has been shown to be anomalously k83 < 3 x 10- l 3 cm3 molecule- s- ' (see also earlier section on H atoms p. 24). Both reactants and products correlate adiabatically via surfaces of ,A' and ,A'' symmetry the surface of ,A' symmetry being attractive according to recent 'non-empirical LCAO-MO-SCF and CI SO.-Fluoresence from SO[(A311) and B(3 C)] has been observed288 following the vacuum-u.v. photolysis (Kr lines 116.5 and 123.6 nm) of SOCl, and has been used to determine the heat of formation of ground-state SO; 5.4 > AGo(SO) > 3.3 kJ mol- '.and should therefore provide an efficient path for fast reaction. The rate constant for the energy-transfer process O,(a'A,) + SO(X 3C-) .-) SO(a'A) + O,(X 3C,-) (84) has been determined as 3.5 x 10- l 3 cm3 molecule-' s-l using e.p.r. with flow-tube techniques.' 74 Br2.-The radiative lifetimes for the vibrational levels u' = 1 to u' = 31 of Br2[311(OU+)] have been determined using a tunable dye laser.289 The observed variations in the lifetimes (0.15-1.2 ps) were attributed to spontaneous pre-dissociation. Despite the use of a laser excitation to a wide range of rotational levels must certainly have been involved (the width of the exciting pulse was 0.1-0.8 nm) and thus the reported lifetimes will not necessarily be the same as those determined using other 'broad band' excitation sources ; considerably higher resolution will be required before the lifetimes of individual vibration-rotation states can be determined (see 1 below).Cross-sections for self-quenching of these vibrational levels were also reported.289 BrF and IF.-Emission from the B311(O+) states of BrF and I F [B311(O+) --* X 'C+] following combination of the atoms in the presence of O,(a'A,) has been reported.lg3 Numerous new band systems have been observed and vibra-tional constants for the ground states of these unstable interhalogens have been given. The role of energy transfer from O,(u'A,) to the states of these inter-halogens populated by the atomic combination processes is discussed.193 12.-Steinfeld290 has recently given a useful review of the various processes important in the non-radiative depopulation of the [B 311(Ou')] state of I,, 2 8 6 D. F. Evans and J. M. Tucker J.C.S. Faraday IZ 1972,68 174. 2 8 7 J. L. Cole and E. F. Hayes J . Chem. Phys. 1972 57 360. 2 8 9 G. Capelle K. Sakurai and H. P. Broida J . Chem. Phys. 1971,54 1728. 2 9 0 J. I. Steinfeld Faraday Discuss. Chem. SOC. 1972 no. 53 155. H. Okabe J . Chem. Phys. 1972 56 3378 68 R. J. Donouan D. Husain and L. J. Kirsch including spontaneous magnetically-induced and collision-induced predissocia-tion. However several points made in that review require some modification in view of the more recent work discussed below. Work on the lifetime of 12[B 3n(0,')] has been reviewed in detail by Telling-h u i ~ e n ~ ~ l (including the recent work by Shotton and Chapman292).The location of the 'lI(1,) state deduced from data on the continuous absorption spectrum, was shown to be consistent with the data on spontaneous predissociation and explains the main features in the variation in the lifetime for the B state vibrational levels. Discrepancies in some of reported data for specified u' levels are attributed to a J(J + 1) rotational dependence of the predissociation (different lifetimes resulting from different J distributions formed in the 'broad band' excitation process). 'Narrow band' excitation of the u' = 11 J = 128 and u' = 6 J = 32 using a modulated He-Ne laser has allowed a very precise determination of the lifetimes of these states.292 A previous proposal293 that quenching of 12[B31T(0,+) v' = 431 proceeds in part uia collision-induced predissociation yielding two I(52P3,2) atoms (in addition to quenching to the ground electronic state and vibrational relaxation), has been re-interpreted208 as due to 'collisional release' to yield I(52P,,2) + I(52P3,,).Thus collisional release is observed from levels 3 kT below the dis-sociation limit with an efficiency of 0.5; the efficiency rises to approximately unity within 2 kT of the dissociation limit.208 These surprisingly high efficiencies clearly have important implications in several areas of photochemistry and chemical kinetics and particularly for theories of atomic recombination. The observation that He and Xe have closely similar efficiencies for collisional release at all energies is another surprising feature208 and cannot apparently be reconciled with available theoretical models ; it also rules out the stabilized atom-molecule-complex mechanism at least for the noble gases.A shortening of the fluorescence lifetime of 12[B 311(0,')] in the presence of a strong magnetic field has been and attributed to mixing of the B state with the repulsive 0,- state induced by the field. The lifetime was ob-served to decrease by up to a factor of two for fields of - 15 kG for some vibra-tional levels. A consideration of the variation in lifetime has allowed the approxi-mate position at which the 0,- state crosses the B state to be located.294 The vibrational relaxation of 12[B 311(0,')] has been discussed in terms of an optical and the influence of open reactive channels (collision-induced predissociation in this case) considered.Vibrational transition probabilities are only affected when the predissociation probability is larger than 0.3. The total cross-section for quenching of 12[B 31T(0,') u' = 61 by I has been determined297 2 9 1 J. B. Tellinghuisen J . Chem. Phys. 1972 57 2397. 2 9 2 K. C. Shotten and G. D. Chapman J . Chem. Phys. 1972,56 1012. 293 R. B. Kurzel and J. I. Steinfeld J . Chem. Phys. 1970 53 3293. 294 G. D. Chapman and P. R. Bunker J . Chem. Phys. 1972,57 2951. 2 9 5 H. P. Broida and G. A. Capelle J . Chem. Phys. 1972,57 5027. 2 9 6 L. L. Poulsen J. Ross and J. I. Steinfeld J . Chem. Phys. 1972 57 1592. 2 9 7 R. B. Kurzel E.0. Degenkolb and J. I. Steinfeld J . Chem. Phys. 1972 56 1784 Reactions of Atoms and Small Molecules 69 as 53 x 10- l 6 cm’ in agreement with the value of Shotten et ~ 1 . ~ ’ ~ [(64 f 3) x 10- l 6 cm2]. Vibrationally inelastic collisions with Ne for Av = f 1 have a c r o ~ ~ - ~ e c t i o n ~ ~ ~ of 1.3 x cm’. Collisional depolarimtion of I,[B 3n(0,’)] has been in~estigated,~” and it was shown that reorientation of angular momentum is only important when accom-panying rotational or vibrational energy changes takes place. Depolarization cross-sections for H He and Ne are reported (typically of the order 10- ’ cm2). Ba0.-Probably one of the most important recent developments in molecular-beam scattering is the reported use of laser-induced fluoresence for observing the vibrational-rotational distribution of reaction products.The product molecules (BaO) resulting from the reaction of a beam of Ba atoms with O,, were excited with a tunable dye laser and the resonance fluorescence spectrum was recorded.55 From a knowledge of the Franck-Condon factors for the transitions involved the relative populations of the Id’ J ” ) states could be deduced from the relative fluorescence intensities. Further developments in the technique will be required to obtain ‘unrelaxed’ rotational distributions ; however the preliminary resultss5 clearly indicate that reliable vibrational distributions may be obtained. The production of electronically excited BaO via the reactions Ba + N,O -+ BaO(A ‘Z) + N, Ba + NO -+ BaO(A ‘Z) + NO (85) (86) has also been rep~rted.~’ Emission from the A ‘C state was observed and it was shown that -0.4% of the reactive events lead to this state for reaction (85).59 Reaction (86) gives a significantly lower yield (-0.03 %) of BaO(A ‘Z) in agree-ment with previous molecular-beam work.Chemiluminescence has also been observed’ using semi-molecular-beam techniques following the reaction of Ba Sr and Ca with NO and N,O. The total cross-sections for beam attenuation with NO lie in the range (90-170) x 10l6 cm2 (see Table 3 for more details) indicating that an electron-jump mechanism is involved and (15-30) x 10- l6 cm2 for N,O. The chemilumines-cence was found to be weakly polarizeds4 in some cases and a model involving the partitioning of angular momentum between rotation and recoil angular momentum of the products was proposed to account for this.HgH.-Vacuum-u.v. absorption spectra of HgH and HgD formed by reaction of Hg(63P0,1) with H and D have been recently reported,’ but no electronic assignments were made. Emission from HgH(’lI + X ,Z’) at 350 nm following reaction between Hg(63P0) and H D, CH, C,H6 C3H8 or n-C,H has been observed. ’ 4 Triatomic Species NH2.-The reactions of NH produced in the pulse radiolysis of NH have been studied by monitoring the ,A p-+ X 2 B transition (597.6 nm) in ab~orption.~’’ 2 9 8 R. B. Kurzel and J. I. Steinfeld J . Chem. Phys. 1972 56 5188 299 S. Gordon W. Muiac and P. Nangia J . Phys. Chem. 1971,75 2087 70 R. J. Donovan D. Husain and L. J. Kirsch The rate constants for reaction with NO (k = 2.7 x 10- '' cm3 molecule- ' s- '), recombination with hydrogen atoms [k"H2+H+M) = 6.1 x cm6 molecule-2 s- ' ; high-pressure limiting rate for M = NH,] and reaction with a second NH, radical [k(M12+NH2) = 1.03 x lo-'' cm3 molecule-' s-'1 were reported.,'' Fluorescence from NH,(A2A ') produced by vacuum-u.v.photolysis of NH , has been employed3" to measure the total cross-sections for removal by He, Ne Ar Kr Xe H, N, NH, and CH (the cross-sections are all close to the gas-kinetic values but with He being least efficient). NO2 .-The fluorescence lifetime of NO continues to receive much attention, and has led to a number of reports which apparently conflict. The present status of this work has been reviewed in considerable detail by Sackett and Yardle~,~" who also present results obtained by narrow band (- 0.08 nm) excitation with a tunable dye laser.Excitation in the region 451.5-460.5nm gave rise to non-exponential decays and 'lifetimes' following excitation in different wavelength regions were found to vary between 62 and 75 p . Anomalies in some previous lifetime measurements were shown to arise from restrictive observation geo-metries (i.e. owing to diffusion of the longer-lived states out of the observation zone). The observation of a short-lived fluore~cence~'~ demonstrates that the states responsible for the relatively high oscillator strength of NO in the visible and ultraviolet can contribute to the fluorescence although it is rather weak. The long-lived fluorescence (z > 80 p s ) was attributed to states associated with the quasi-continuous ab~orption.~' ' It was concluded that transitions to both the ,B1 and ' B electronic states occur over a large portion of the visible spectrum, with the ,B transition being the stronger (both states are also perturbed).," In view of the stimulus provided to theoretical treatments it is to be hoped that further work in this area using even narrower excitation sources will be forth-coming in the near future.The relative fluorescence efficiency for NO, excited in the wavelength range 380-520 nm (with 0.01-0.1 nm resolution) has been examined and shown to be constant in the region 415-520nm.303 Below 415nm the fluorescence efficiency declines rapidly but indicates that thermal rotational energy of NO, can be used to reach the threshold for predissociation even for electronic excita-tion just below threshold (Thrush304 has pointed out that this argues against predissociation by rotation being important).Results on the quantum yield for photodissociation in the threshold r e g i ~ n ~ " . ~ ' ~ support the fluorescence data, and the relevance of these results to the two-body radiative recombination of 0 + NO has been disc~ssed.~'~ 3 0 0 M. Lenzi J. R. McNesby A. Mele and C. N. Xuan J . Chem. Phys. 1972,57 319. 301 P. B. Sackett and J. T. Yardley J. Chem. Phys. 1972,57 152. 302 P. B. Sackett and J. T. Yardley Chem. Phys. Letters 1971 9 612. 3 0 3 E. R. C. Lee and W. Uselman Faraday Discuss. Chem. SOC. 1972 no. 5 3 p. 125. 304 B. A. Thrush Faraday Discuss. Chem. SOC. 1972 no. 53 p. 142.3 0 5 J. Troe I. T. N. Jones and K. D. Bayes Faraday Discuss. Chem. SOC. 1972 no. 53 3 0 6 H. Gaedtke H. Hippler and J. Troe Chem. Phys. Letters 1972 16 177. 307 D. Kley Faraday Discuss. Chem. SOC. 1972 no. 53 p. 150. p. 148 Reactions of Atoms and Small Molecules 71 The 'photofragment spectrum' of NO resulting from excitation at 347.1 nm, indicates that 60 % of the available energy appears as translational motion of the recoiling fragments.,08 However the possibility that large numbers of slowly recoiling fragments are formed and which would be undetected by the apparatus employed could not be ruled out. Energy transfer from NO, excited by visible light to 0 uiu NO2(,Bl?) + O,(X 'Xg-) -+ N0,(w2A1) + O,(a'Ag) has been observed.309 The efficiency for transfer is low varying with the wave-length for NO excitation from 3 % at 400 nm to 0.5 % at 600 nm.However this would be sufficient to provide a significant source of 02(u1Ag) in some polluted atmospheres. ,09 NF .-The absorption bands of NF centred at 260 nm have been employed to monitor the kinetics of this radical produced by thermal dissociation of N,F4 in a low-pressure flow ~ystem.~ ' Recombination in the presence of He Ar 0 , NO or SF was investigated : (87) NF + NF + M A N2F4 + M (88) Values of k were given as k, = (1.26 f 0.15) x k, = (0.76 f 0.15) x 0.18) x cm6 molecule-2 s - ' at 293 K. The equilibrium constant was also measured for M = Ar by observing the concentration of NF in equilibrium with N2F4 following reaction in both directions (i.e. recombination of NF and dissociation of N2F4 at 'infinite' reaction time).A comparison of the forward and back reactions (shock-tube studies) with the equilibrium constant shows agree-ment within the combined uncertainties (i.e. within a factor of two).310 Further comparison with shock-tube data indicates that the temperature coefficients for recombination by the third bodies studied are significantly different. The reactions of NF with C1(3,P3,,) Br(4,P3/,) N(24S,i2) and O(2,PJ) were also studied and it was shown that removal of C1 and Br proceeds via the sequence lo-,, kSFa = (2.9 f 0.3,) X kNo % 0.6 X and ko = (0.98 & X + NF + M NF,X + M NF,X + X 5 NF + X, with kk = (2.7 & 0.4) x lo-,' and (1.0 f 0.2) x cm6 molecule-2 s - l for C1 and Br respecti~ely.~'' Removal of NF by N atoms produces fluorine atoms and the stoicheiometry for the reaction suggests that either or N + NF2 --* N2 + F2 N + NF -+ 2NF 2NF -+ N + F, are involved.lo 3 0 8 G. E. Busch and K. R. Wilson J . Chem. Phys. 1972,56 3626 3638. 3 0 9 I. T. N. Jones and K. D. Bayes Chem. Phys. Letters 1971 11 163. 310 M. A. A. Clyne and J. Connor J.C.S. Faraday II 1972,68 1220 72 R. J. Donovan D. Husain and L. J. Kirsch HO .-The molecular modulation technique has been employed to study the infrared and ultraviolet absorption spectra of the HO radical (absorption cross-sections are given as 4.5 x 10- '* cm2 at 210 nm and 5 x lo-,' cm2 at 1395 cm- 1).3 ' ' HO was produced from a number of sources including the photolysis of H,O (253.7nm) photolysis of 0 (253.7nm) in the presence of H,O, and photolysis of C1 (350 nm) also in the presence of hydrogen peroxide.The structure of the radical was deduced from infrared data (H-0-0 angle = 108" ; 0-0 distance 0.13 nm ; 0-H distance 0.096 nm).31 ' The rate constant for the disproportionation reaction HO + HO -% H,O + 0 (94) was found3 ' ' to be k, = (3.6 f 0.5) x 10- ' cm3 molecule- ' s- in agreement with the value given previously312 by Foner and Hudson (3 x 10- l 2 cm3 mole-cule- ' s- ') but differing significantly from the recent value3 l3 by Hochanadel et al. r(9.5 & 0.9) x cm3 molecule-' s-'1. The latter authors produced HO by the flash photolysis of water vapour in the presence of 0 (plus a 100-fold excess of inert gas) and report an extinction coefficient for HO2 at 210 nm which is - 32 % lower than that given by Paukert and John~ton.~ '' The rate constant for the reaction HO + OH -+ H,O + 0 (95) has been determined313 as (2.0 & 0.3) x lo-'' cm3 molecule-' s-'.SO .-The fluorescence of SQ from the and d states has been studied using single-photon counting technique^.^ l4 A decrease in the lifetime and fluorescence quantum yield was observed for 2 < 220.6 nm resulting from the opening of the dissociative channel leading to SO + 0 which becomes accessible at this energy (in agreement with Okabe3 "). For excitation above the dissocia-tion limit the lifetime was observed to decrease relatively slowly3 l4 (see Table 28), Table 28 Fluorescence data for SO, 229.75 227.7 1 226.09 225.8 224.3 222.41 220.63 218.78 216.93 215.24 z/ns 31.82 32.77 35.28 33.39 3 8.70 41.27 45.41 28.11 9.63 7.81 @,/(no rmaltzed) 0.907 1.0 0.98 0.956 0.919 0.745 0.664 0.151 0.0714 0.0244 3 1 1 T.T. Paukert and H. S. Johnston J . Chern. Phys. 1972,56,2824. 3 1 2 S . N. Foner and R. L. Hudson Adv. Chern. Ser. 1962 no. 36 p. 42. 3 1 3 C. J. Hochanadel J. A. Ghormley and P. J. Ogren J . Chern. Phys. 1972,56,4426. 'I4 Man-Him Hui and S. A. Rice Chern. Phys. Letters 1972 17,474. 3 1 5 H. Okabe J . Arner. Chem. SOC. 1971,93 7095 Reactions of Atoms and Small Molecules 73 indicating that the internal redistribution of energy is inefficient in small molecules, in agreement with theoretical predictions. Coupling between the c and d states and states belonging to other electronic manifolds was shown to be weak in contrast to the SO,('B,) state.314 The role of excited states of SO in the photo-chemical reaction with CO yielding CO has been disc~ssed.~' Collision-induced intersystem crossing from the singlet- to triplet-state manifold occurs with an efficiency of 3-9 % withN cyclo-C6H ,, or so as collision partner^.^^ CO ' ( A 'ill and B2 C,+).-Rate data for quenching of C02+[B2 Xu+ (O,O,O)] and CO,+[A ,nu (3,0,0)] have been reported.318 These states were formed by photolysis of CO with the He(1) line at 58.4 nm ; however emission from the C state which should also be populated at this wavelength (photoelectron data), could not be detected suggesting that spontaneous predissociation is significantly faster than radiative processes for this state.Stern-Volmer plots of the A -P X and B -P X emission following the addition of various quenching gases yielded relative rate data which were converted into absolute data using independently determined values for the radiative lifetimes of these states (zA = 1.5 x s; zB = 1.4 x s). Quenching by the molecules CO, H, N, O, CO N,O, C& Ar Ne or He was inve~tigated.~'~ Charge transfer to the quenching species is possible for all but He and Ne which are observed to be least efficient. The high quenching efficiencies observed for the other molecules (typically 3 0 - 4 times the gas kinetic collision rates) strongly suggest that charge transfer is an important channel although this could not be checked directly.318 quenching of CO,+[A 2nu(0,0,0)] was reported together with data for quenching of N,+(B ,Xu+) and N,O+(A 'Xu+). The quenching gases studied were NO C2H6 O, N,O CO, CO H, N,, Ar and He. A comparison of the results given for the different ions suggests that effects due to 'chemical interactions' are superimposed on the basic charge-transfer mechanism. In later work by Phillips et 5 Tetra-atomic Species CH .-The combination reaction between methyl radicals and molecular oxygen has been re-examined in detail using flash spectroscopy to monitor the CH,(P *- x) transition.320 The order of the reaction was found to lie between 2 and 3 for pressures of 25-380 Torr (at 295 K) and the results were shown to be consistent with the simple reaction sequence a CH + 0 'T; CH302* CH302* + M --* CH302 + M (97) 3 1 6 F. Wampler A. Horowitz and J. G. Calvert J . Amer. Chem. Soc. 1972,94 5523. 317 A. Horowitz and J. G. Calvert Znrernar. J . Chem. Kinetics 1972 4 191. C. A. Winkler J. B. Tellinghuisen and L. F. Philips J.C.S. Faraday ZI 1972 68 121. 3 1 9 J. B. Tellinghuisen C. A. Winkler C. G. Freeman M. J. McEwan and L. F. Phillips, J.C.S. Faraday ZZ 1972 68 833. 320 N. Basco F. C. James and D. G. L. James Znrernar. J . Chcm. Kinetics 1972 4 129 74 R. J. Donovan D. Husain and L. J. Kirsch The limiting value for the second-order rate coefficient at high pressure was given320 as (5.2 0.5) x 10- '' cm3 molecule-' s- ' which is a factor of three lower than the value determined by Callear et a1.321 using the same technique. However the limiting values given for the third-order rate coefficients at low pressures320 [(1.0 0.1) x lo-,' cm6 molecule-2 s-' for M = neopentane; (2.6 & 0.1) x cm6 molecule-2 s-' for M = N2] appear to be con-sistant with the data of Callear et ~ 1 . ~ ~ ~ (-6.1 x lo-,' cm6 molecule-2 s-' for M = propane). It was also shown that the rate constant for the reaction CH + 02+ CH20 + OH (98) has a low value (-3 x cm3 molecule-'^-^) and that this channel was therefore unimportant under the conditions used.320 A brief review of the pre-vious work on these reactions was given and the data were presented in con-venient graphical form ;320 this emphasizes the widely divergent results which have been presented for this ~ y s t e r n . ~ * ' ~ ~ ~ 32' A. B. Callear and H. E. van den Bergh Trans. Furuduy SOC. 1971,67,2107. 322 G. R. MacMillan and J. G. Calvert Oxidation and Combustion Rev. 1965 1 83

ISSN:0069-3022    

DOI:10.1039/GR9726900019

出版商:RSC    

年代:1972

数据来源: RSC

摘要:

3 Mixtures of Simple Liquids By I. R. McDONALD Department of Chemistry Royal Hollowa y College Englefield Green Surrey 1 Introduction Some very remarkable advances have been made in the theory of simple liquid mixtures in the comparatively short period since the topic was last reviewed in the pages of Annual Reports.’-3 Much of this progress may be ascribed to three factors first a variety of theoretical approaches which had previously been applied successfully to the problem of pure fluids including in particular, theories of the perturbation type have now been extended to include the case of mixtures ; secondly the n-fluid theories which grew out of the important concept of the random mixture have been replaced by improved models based in part on the ideas of van der Waals ; and thirdly the results of large-scale Monte Carlo computations for mixtures of Lennard-Jones molecules have become available.The subject matter of the present review is limited to a discussion of the calculation of excess thermodynamic properties of binary mixtures of molecules which interact via spherically symmetric pair-wise additive potentials and for which quantum effects are negligible. Specific reference is made to two potential models. The first of these is the hard-sphere potential defined by the relations 1 q,j(r) = coy Y < d, = 0 Y 2 dij where dij is the hard-sphere diameter for species i andj. Quite cleslrly this poten-tial does not adequately represent the interaction between real molecules. In particular because there is no attractive region to the potential the hard-sphere fluid can have no true liquid phase and the only phase transition is that between solid and fluid.A second more realistic model is the Lennard-Jones 12-6 potential : where cij is the depth of the potential well and oij is the collision diameter i.e. qi,(oij) = 0. A mixture of 12-6 fluids provides an example of a conformal mixture, ‘ N. G. Parsonage Ann. Reports ( A ) 1967,64 57. N. G. Parsonage Ann. Reports ( A ) 1968 65 33. I. R. McDonald and K. Singer Ann. Reports ( A ) 1970 67 45. 7 76 I. R. McDonald i.e. one in which all pair potentials have the form q ( r ) = ~F(r/a) where E and a are parameters and the function F is the same for all interactions. The goal of a theory of mixtures is not so much the calculation of the properties of the mixture itself but the properties of mixing.In the case of liquid mixtures the properties of greatest interest are the excess thermodynamic functions for mixing at constant pressure the excess Gibbs free energy GE excess enthalpy HE and excess volume VE. It is with the calculation of these quantities that the theories reviewed here are largely concerned. Recent experimental results are discussed in Section 2 and theoretical work is described in Sections 2-5 ; com-parison between theory and experiment is largely reserved for Section 6. The material is similar to that in a recent Specialist Periodical Report4 but more emphasis is placed on the latest developments. Other accounts of the theory of mixtures may be found in two recent publications uiz.the second edition of the monograph by Rowlinson’ and an authoritative review article by Henderson and Leonard. 2 Experimental Results It is convenient to use the word experimental to refer both to measurements made on real liquid mixtures and to computer ‘experiments’ on model systems7 In practice it is found that computer simulation provides the more useful data against which to test theories. The reason for this is that the machine calculations are free of any uncertainty about the form of the various pair potentials in the mixture. The simulation work is of course the only source of experimental data on systems of hard spheres. Extensive studies in which computer experiments have played an important role,* have shown that the Lennard-Jones 1 2 4 potential is a satisfactory eflectiue pair potential for simple liquids.The latter group includes not only the heavier noble-gas liquids (Ar Kr and Xe) but also liquids composed either of small diatomic molecules e.g. N2 0, and CO or of quasi-spherical molecules such as CH and CF,. On the other hand it is now known that the true pair potential in such systems is certainly not of the 12-6 form. In the case of Ar for example, the pair potential between isolated atoms has a deeper and narrower bowl and a weaker tail than the 12-6 potential which best reproduces the bulk properties of the liquid.9-” This apparent anomaly may be resolved by including the effects of weak and predominantly repulsive three-body forces. However it is also fair to say that the thermodynamic properties of the liquid are not very I.R. McDonald in ‘Statistical Mechanics’ ed. K. Singer (Specialist Periodical Reports), The Chemical Society London 1973 vol. 1 . J. S. Rowlinson ‘Liquids and Liquid Mixtures’ Butterworth London 2nd edn. 1969. D. Henderson and P. J. Leonard in ‘Physical Chemistry An Advanced Treatise’ ed. H. Eyring D. Henderson and W. Jost Academic Press New York 1971 vol. VIII, ch. 7. ’ I. R. McDonald and K. Singer Quart. Rev. 1970 24 38. * I. R. McDonald and K. Singer Mol. Phys. 1972 23 29. J. A. Barker and A. Pompe Austral. J . Chem. 1968 21 1683. l o M. V. Bobetic and J. A. Barker Phys. Rev. (B) 1970 2 4169. * J. A. Barker R. A. Fisher and R. 0. Watts Mol. Phys. 1971 21 657 Mixtures of Simple Liquids 77 sensitive to the precise form of the pair potential and that a number of different potentials may be made to fit the experimental data by choosing suitable values for the interaction parameters.Despite its known inadequacies the 12-6 potential is a common choice in theoretical work on liquids primarily because of its simple analytical form. In applying the 12-6 potential to mixtures the interaction parameters for species 1 and 2 are most frequently determined from the well-known combining rules : = ( E ~ ~ E ) * (Berthelot rule) (3) cr12 = +(oll + G,,) (Lorentzrule) (4) Such a system is called a Lorentz-Berthelot mixture. The parameter c12 may, in principle be determined directly from measurements of either the cross second virial coefficientI2 or the composition dependence of the critical temperature.l 3 The measurements which exist are not very precise but the general trend suggests strongly that E ' is very nearly always some one to two per cent less than that given by the geometric mean of E~~ and E,,. For this reason a number of other combining rules have been proposed,14*15 but it is often more useful to retain the general form of equation (3) and write The quantity k is a pure number of the order of unity which may be treated as an adjustable parameter and varied so as to force agreement between theory and experiment for one selected property of the mixture. In the past less doubt has been cast on the validity of the arithmetic-mean rule for cr1 equation (4) which is exact in the case of hard spheres. Recently it has been suggested by Good and Hope'67 l 7 that better results on cross virial coeffi-cients may be obtained if a geometric-mean rule is used.The experimental data which they use to support their argument all refer to mixtures of relatively complex molecules. It is possible of course to treat both E and o12 as variable quantities and thereby to obtain agreement between theory and experiment for a wider range of properties but is questionable whether any great significance can be attached to the results of such manipulations. Henderson and Leonard6 have given an excellent summary of the experimental measurements of excess thermodynamic properties of mixtures of real simple liquids which covers the period up to 1969. To this should be added the measure-ments made some years ago on N2 + CH4.'8i'9 Systems of interest for which I ' M.A. Byrne M. R. Jones and L. A. K. Staveley Trans. Faraday SOC. 1968,64 1747. '' 1. W. Jones and J. S. Rowlinson Trans. Faraday SOC. 1963,59 1702. l 4 G. H. Hudson and J. C. McCoubrey Trans. Faraday SOC. 1960 56 761. I s B. E. F. Fender and G. D. Halsey J . Chem. Phys. 1962,36 1881. '' R. J. Good and C. J. Hope J . Chem. Phys 1970,53,540. " R. J. Good and C. J. Hope J . Chem. Phys. 1971,55 1 1 1. l 9 S. Fuks and A. Bellemans Bull. Soc. chim. belges 1967 76 290. F. B. Sprow and J. M. Prausnitz Amer. Ins?. Chem. Engineers J. 1966 12 780 78 I. R. McDonald data have since been reported include Kr + Xe,20*2' Ar + Kr,21 Kr + CH4,22 and Ar + CH4.23 The situation at present is that data are available on GE HE, and VE (not necessarily all at the same temperature) for Ar + Kr Ar + N2, Ar + CH, O2 + Ar O2 + N2 CO + CH4 and Kr + CH4 and on GE and VE alone for Kr + Xe Ar + CO N2 + CO N2 + CH, and CH4 + CF,.The values reported by different authors are often in poor agreement with each other, particularly when account is taken of measurements made over a range of temperature and it is clear that some of the published results are significantly in error. Added to the inaccuracies in the measurement of excess properties are the inevitable uncertainties about the detailed form of the pair potentials. This combination of factors means that it is rarely possible to make unambiguous comparisons between experimental data on real systems and the predictions of different theoretical approaches.In particular it is known that small departures from the Lorentz-Berthelot rules may result in large changes in the magnitude, and even a change in sign of the excess properties. Much greater reliance may be placed on data obtained from computer experiments based either on the method of molecular dynamics or on the Monte Carlo method. Machine calculations of this type provide what is essentially exact information on the consequences of a given intermolecular force law. Their success arises primarily from the fact that a model containing a relatively small number of particles (usually several hundred with suitable boundary conditions) is in general found to be sufficient to simulate the behaviour of a macroscopic system. As the model may be chosen to correspond to any set of parameter values for a given potential it is possible to study systematically the relation between interaction parameters and the thermodynamic properties of the mixture and thereby to determine the range of applicability of different theories.In the method of molecular dynamics the classical equations of motion of a system of interacting particles are solved numerically and equilibrium properties are determined from time averages taken over a sufficiently long time interval (- 10- s). The Monte Carlo procedure involves the generation of a series of configurations of the particles of the model in a way which ensures that the configurations are distributed in phase space according to some prescribed probability density. The mean value of any configurational property determined from a sufficiently large number (- lo6) of configurations provides an estimate of the ensemble-average value of that quantity.The character of this ensemble average depends upon the chosen probability density. Most applications of the Monte Carlo method to the study of fluids have been based on the usual Gibbs petit-canonical constant volume or NVT-ensemble but work has also been carried out based on the isothermal-isobaric or NpT-ensemble. The NpT-ensemble is a natural choice for the study of liquid mixtures particularly of the J. C. G. Calado and L. A. K. Staveley Trans. Faraday SOC. 1971,67 289. 2 1 C. Chui and F. B. Canfield Trans. Faraday SOC. 1971 67 2933. 2 2 J. C. G. Calado and L. A. K. Staveley Trans. Faraday SOC. 1971 67 1261 23 J.C. G. Calado and L. A. K. Staveley J . Chem. Phys. 1972 56,4718 Mixtures of Simple Liquids 79 excess properties because the results required are almost invariably the changes which occur on mixing at constant (usually near-zero) pressure. Data obtained by the NVT-method may be processed in such a way as to provide information on changes in thermodynamic properties in the constant-pressure mixing process but this requires additional rather tedious calculations. The NpT-method has its own disadvantages but it does have the merit of yielding the required results in an attractively direct manner. In practice however the two methods are found to yield data of approximately equal statistical reliability for a given expenditure on computing time and the choice of which to use is largely a matter of taste.Results for mixtures of hard spheres were obtained some years ago both by molecular dynamics24 and by the Monte Carlo meth~d.~’-~’ The major advan-tage of molecular dynamics is that it allows the study of time-dependent pheno-mena. For the calculation of equilibrium properties the Monte Carlo method is generally more suitable and published results on excess properties for the 12-6 potential model have all been obtained in this Two lengthy series of Monte Carlo computations have recently been made for binary mixtures of 12-6 liquids one in the NpT-en~emble~~* 31 and the other based on the NVT-meth~d.~’ In most of the calculations the parameters gl and nl2 (given by the Lorentz-Berthelot rules) were held constant and the ratios E ~ J E and 611/422 were systematically varied.Further reference to these results will be made in Section 6 where the reliability of different theories is discussed. Results have also been obtained for some model systems simulating real mixtures and these are shown in Table 1. The agreement between the NpT- and NVT-calculations is good. Agreement between computation and experiment on the other hand is generally rather poor. Some improvement may be achieved by varying the quantity k,, and the values of k which are listed in Table 2 are those required to bring the calculated values of GE into agreement with experiment. Though some dis-crepancies remain the results for HE and VE based on the modified values of k12 are overall in substantially better agreement with experiment.It can be seen from Table 2 that the adjusted value of k, is less than unity for all mixtures except Ar + N2 and the small positive deviation found for this system is in-significant in comparison with the combined errors in the experiments and the computations. Thus the conclusion to be drawn both from liquid-state measure-ments and from the analysis of gas-phase data is that it is the rule rather than the exception for to be less than that given by the geometric-mean relation, equation (3). 2 4 B. J. Alder J . Chem. Phys. 1964 2724. ’’ 2 6 E. B. Smith and K. R. Lea Trans. Furaday SOC. 1963,59 1535. 2 7 A. Rotenberg J . Chem. Phys. 1965,43,4377. ” I. R. McDonald Chem. Phys. Letters 1969 3 241. 2 9 1. R. McDonald Mol. Phys.1972 23 41. 3 0 J. V. L. Singer and K. Singer Mol. Phys. 1972,24 357. 3 1 E. B. Smith and K. R. Lea Nature 1960 186 714. I. R. McDonald Mol. Phys. 1972 24 391 00 0 Table 1 Comparison4 between experimental excess thermodynamic properties of equimolar mixtures and the predictions of various theories p = 0 k, = 1 System T/K experiment (a) GE/J mol-MC-NpT" MC-NVT~ RM' APMd vdW 1 vdW2f PYP Pert.h Var.' (b) HE/J mol-experiment MC- Np T MC-NVT RM APM vdWl vdW2 PY Pert. Var. Ar + Kr 116 + 84 +46+7 + 45 + 203 + 139 + 46 + 61 +41 + 39 + 47 Ar + N Ar + 0, 84 84 + 34 + 37 +35+5 - + 35 0 + 98 + 57 + 39 + 27 + 32 + 42 ----- ---- +51 + 60 -29+17 +16*9 -- 18 +40 0 + 254 + 142 -+ 162 + 78 - 30 + 43 + 18 + 28 - 30 - 28 + 35 - 31 + 42 ---- ---Ar + CO 84 + 57 +26+5 + 27 + 99 + 55 + 29 + 20 + 25 + 28 --+37? 15 + 34 + 149 + 80 + 35 + 22 + 30 + 37 -Ar + CH, 91 + 74 -14&6 - 10 + 227 + 159 - 17 +9 - 12 - 12 -Xe + Kr N +O CO +CH CH,+CF, 161 84 91 111 +.115 + 39 +115 + 360 +381t5 +77&7 - + 28 + 38 + 76 - 28 - + 143 + 137 -- + 80 +111 - + 43 + 83 + 29 + 84 + 36 + 69 -- -- -- - - -- -- + 76 - -- + 103 -60$12 -- 35 - 52 +406 - + 223 -- 55 -11 -- 30 - 34 -- ---+ 42 +39& 15 + 48 + 220 +118 + 52 + 33 + 42 -+ 105 -+15+12 - + 13 + 59 + 96 + 26 + 52 - - *+ + 24 + 30 - + 115 --- 4 - 2 -0 3 (c) VE/cm3 rnol-' experiment MC-NpT MC-N VT RM APM vdWl vdW2 PY Pert.Var. -0.52 - 0 69 j- 0.06 - u.60 + 0.42 + 0.09 - 0.68 - 0.47 - 0.62 - 0.73 --0.18 +0.14 -0.25k0.05 -- 0.23 0.00 +0.11 -- 0.02 --0.25 -- 0.20 - 0.23 - 0.26 -- ---+ 0.10 +0.17 -- 0.1 7 & 0.05 - 0.22 & 0.04 --0.17 -0.13 - 0.62 + 0.23 + 1.34 - + 0.05 + 0.6 1 --0.19 - 0.23 --0.16 -C.17 --0.17 -0.12 --0.17 -0.14 -- - -;i g F 2 % ki - 5 tcl 6' E - & -0.31 - 0.32 + 0.88 - 0.28 & 0.06 - 0.76 & 0.06 -+0.35 -0.32 -+ 0.38 - 0.30 - 0.28 -0.71 -- 0.24 -0.50 -- 0.25 - 0.63 - 0.25 - 0.68 -0.10 $ - --- -0.75 -Monte Carlo-NpT method. * Monte Carlc -NVT method. Random-mixing approximation. ' Average Potential Model. One-fluid van der Waals model.Two-fluid van der Waals model. Percus-Yevick theory. ' Perturbation method. Variational method Table 2 Comparison between experimental excess thermodynamic properties of equimolar mixtures and the results of Monte Carlo calculations,p = 0 k # 1 System Ar + Kr Ar + N Ar + 0, T/K 116 84 84 (a) k , MC-NpT 0.989 1.001 -MC-NVT 0.989 1 .Ooo 0.988 (b) HE/J mol-* experiment - +51 + 60 MC-NpT +29 + 34 -MC-NVT +36 + 40 + 52 (c) vE/cm3 mol-' experiment -0.52 -0.18 +0.14 MC-N V T - 0.5 3 - 0.23 + 0.06 - MC-NpT - 0.60 - 0.25 Values of k are adjusted to fit experimental data on GE. Ar + CO 84 0.989 0.989 - + 79 + 79 +0.10 -0.10 -0.11 Ar + CH Xe + Kr 91 161 0.975 -0.976 0.98 1 - + 103 + 57 +83 --+0.17 - 0.70 -0.11 -- 0.01 - 0.47 N2 + 0, 84 0.999 1 .Ooo - + 42 + 42 -0.31 - 0.28 - 0.25 CO + CH CH + CF, 91 111 0.988 -0.988 0.900 + 105 -- + 70 - + 67 - 0.32 - 0.88 - 0.68 --0.61 + 0.8 Mixtures of Simple Liquids 83 3 Distribution Function Theories If the intermolecular potentials are spherically symmetric a knowledge of the pair distribution functions gijr) is sufficient to determine the equation of state of the mixture.However the calculation of the functions gijr) is a formidable task. In the case of pure liquids the most widely used theory of this type is that due to Percus and Y e ~ i c k . ~ ~ The extension of their approach to the problem of mixtures is straightforward and has been considered by a number of author^.^^-^^ It is convenient first to define the total correlation function hijr) as hiAr) = gijr) - 1 (6) The total correlation function is related to the direct correlation function ci,{r) through a generalization of the well-known Ornstein-Zernike relation : where p = N / V is the number density and the sum is taken over all components (labelled k) in the mixture.The Percus-Yevick approximation is given by ci,{r> = gijr)(1 - ex~[qi,{r)/kTI) (8) Substitution of (8) into (7) yields a set of coupled non-linear integral equations for the functions g&). When these are solved the thermodynamic properties of the mixture may be calculated uia one of several different routes the well-known statistical mechanical expressions for the pressure (the virial theorem) the com-pressibility and the configurational energy may all be used.These expressions all have the form of integrals with respect to r of functions involving g&) and if the g&) were exact they would yield identical results. In practice slightly different results are obtained because the approximation described by equation (8) has been introduced. L e b ~ w i t z ~ ~ and B a ~ t e r ~ ~ have solved the Percus-Yevick equations exactly for hard-sphere mixtures with additive diameters i.e. systems for which dl2 = 241 + d22) (9) and have succeeded in obtaining the equation of state in closed form. Comparison with the simulation results of various workers shows that p” (the solution of the compressibility equation) and p’ (the solution of the virial or pressure equation) bound the true pressure at all densities in the fluid range.35 An excellent fit to the machine calculations is obtained36 by taking a linear combination of the 32 J.K. Percus and G. J. Yevick Phys. Rev. 1958 110 1. 3 3 J. L. Lebowitz. Phys. Rev. 1964 133 A895. 3 4 R. J. Baxter J. Chem. Phys. 1970 52 4559. 3 5 J. L. Lebowitz and J. S . Rowlinson J. Chem. Phys. 1964,41 133. 36 G. A. Mansoori N. F. Carnahan K. E. Starling and T. W. Leland J. Chem. Phys., 197 1,54 1523 84 I. R. McDonald solutions : p = $pc -k $pv This represents a generalization to the case of mixtures of a similar proposal made for the one-component hard-sphere fluid by Carnahan and Starling.37 Mansoori et al.36 have used equation (10) to evaluate the excess thermodynamic properties of a binary mixture in which x1 = x2 = 3 and dl1/dzz = 3 for comparison with the molecular dynamics data of Alder.24 Agreement is found to be good even at this large value of the diameter ratio and the authors conclude that equation (10) represents the best available analytical equation of state for hard-sphere mixtures.The results themselves are of interest for the light they may throw on the behaviour of real systems. There is a pressure drop on mixing at constant volume which increases rapidly with increasing density. Mixing at constant pressure leads to a contraction in volume at all ratios of molecular diameters and all densities in the fluid range. It follows that GE is also invariably negative and consequently there is no phase separation of the components. The absolute value of GE is small which suggests that in real mixtures large values of GE must be associated with differences in the attractive forces.Equation (10) could also be used in calculations for real systems by incorporating it into a generalized equation of state of the van der Waals type. 38-42 The Percus-Yevick equations cannot be solved analytically for the 1 2 4 potential and numerical methods must be used. The pair distribution functions and excess thermodynamic properties of a number of 12-6 mixtures at low den-sities and high temperatures were calculated some years ago by Throop and Bearman.43* 44 The systems were chosen to represent binary mixtures formed from Ne Ar and Kr but qualitatively the results were the same in all cases. For mixing at constant pressure GE VE and the excess internal energy are all positive at low densities increase to a maximum with increasing density and then decrease ; both GE and V E become negative at high densities.The excess functions for mixing at constant volume are much smaller than for the constant-pressure process. Only recently have Percus-Yevick calculations been attempted in the liquid range. Grundke Henderson and Murphy45* 46 have obtained results for a system representing an equimolar mixture of Ar and Kr at the triple-point temperature of Kr (116 K). The thermodynamic functions were obtained by integrating the equation for the configurational energy. This is known to be the most accurate route to the thermodynamic properties in the case of pure and thus presumably for mixtures also.3 7 N. F. Carnahan and K. E. Starling J . Chem. Phys. 1969 51 635. 3 8 M. Rigby Quart. Rev. 1970 24 416. 39 H. C. Longuet-Higgins and B. Widom Mol. Phys. 1964 8 549. 40 M. L. McGlashan Trans. Faraday SOC. 1970,66 18. 4 1 K. N. Marsh M. L. McGlashan and C. Warr Trans. Faraday SOC. 1970,66,2453. 4 2 N. S. Snider and T. M. Herrington i. Chem. Phys. 1967 47 2248. 4 3 G. J. Throop and R. J. Bearman J . Chem. Phys. 1966,44 1423. 44 G. J. Throop and R. J. Bearman J . Chem. Phys. 1967 47 3036. 4 5 E. W. Grundke D. Henderson and R. D. Murphy Canad. J . Phys. 1971,49 1593. 4 6 E. W. Grundke D. Henderson and R. D. Murphy Canad. J . Phys. in the press. 4 7 J. A. Barker D. Henderson and R. 0. Watts Phys. Letters ( A ) 1970 31 48 Mixtures of Simple Liquids 85 49 has been extended by Gibbons5’* 5 1 to include mixtures of hard convex particles of arbitrary shape.Scaled-particle theory is an example of a distribution function theory because the quantity evaluated which determines the equation of state is the value of the pair distribution function at contact. The procedure used is to write down an expression for the reversible work needed to create a cavity within the fluid and relate this to the average density of particles at the boundary of the cavity. The equation of state which is derived in this way involves the volume the surface area, and the mean radius averaged over all orientations of particles of each species in the mixture. When the values appropriate to hard spheres are substituted the result reduces to that obtained from the Percus-Yevick theory via the com-pressibility equation.Results have been obtained for mixtures of hard spheres, cylinders cubes tetrahedra and ellipsoids. It is found that VE is always negative and so therefore is GE. The effect of shape on VE is much less than that of size ratio. The apparent lack of any simple relationship between the shape and VE at a fixed temperature and pressure suggests that there is no equivalent sphere whch can reproduce the mixing properties of a non-spherical particle. Little effort has yet been made to interpret the properties of mixtures of real molecules in the light of these results. The scaled-particle theory of hard-sphere 4 n-Fluid Theories Until comparatively recently most statistical thermodynamic treatments of liquid mixtures were based on what have become known as n-Juid models.In theories of this type the properties of a binary mixture are taken to be those of either a single imaginary pure fluid (a one-fluid model) or of an ideal mixture of two imaginary components (a two-fluid model); a three-fluid model has also been proposed but has not been widely used for liquid mixture^.^^^'^ The inter-molecular potentials which characterize the hypothetical substances are formed by taking some suitable composition-dependent average of the potentials in the various components of the real system and theories of t h s class differ from each other in the way in which the average potentials are computed. Practical calculations are simplified if the pair potentials in the mixture and the average potentials are conformal with each other because the thermodynamic properties of mixing may then be obtained from those ofa single reference system by applica-tion of the law of corresponding states.For this reason most calculations for real systems have been based on the 1 2 4 potential model. The various n-fluid models which have been proposed have been put forward on the basis of a variety of arguments. Henderson and Leonard6. 5 3 have been 4 8 H. L. Frisch Adv. Chem. Phys. 1964 6 229. 4 9 D. Henderson and S. G. Davison in ‘Physical Chemistry An Advanced Treatise’ ed. H. Eyring D. Henderson and W. Jost Academic Press New York 1967 vol. 11, chap. 7. R. M. Gibbons Mof. Phys. 1970 18 809. ’’ R. M. Gibbons Mof. Phys. 1969 17 81. 5 1 5 2 D.Henderson and P. J. Leonard Proc. Nu,. Acad. Sci. U.S.A. 1970,67 1818. 5 3 D. Henderson and P. J . Leonard Proc. Nut. Acad. Sci. U.S.A. 1971,68 632 86 I. R. McDonald able to show however that the essential features of all the widely used models can be expressed very simply in terms of molecular distribution functions. For example the assumption expressed by equation (1 I ) generates the (one-fluid) random-mixing approximation of Prigogine and others.5L62 The quantity gx(r) is interpreted as the pair distribution function in a hypothetical pure fluid called the equivalent substance which is characterized by a composition-dependent pair potential cp,(r) = &,F(r/aX) given by i j The rather more plausible assumption, leads to the two-fluid Average Potential Model of which a detailed account has been given by Bellemans Mathot and Simon.63 The quantity gll(r) is now interpreted not as the pair distribution function for species i in the mixture but as that in a pure fluid having a pair potential The two fluids in the model are those characterized by the pair potentials q J r ) (i = 1 or 2) with parameters The random-mixing rule equation (12) may also be deduced by assuming that all permutations of molecules amongst positions in a given configuration are equally probable.This is a poor approximation when the molecules differ in size because it ignores the size-ordering effect which is the most important factor determining the structure of such systems. The inadequacy of the model is particularly obvious in the case of hard-sphere mixtures because in general the interchange of a large sphere with a small one leads to molecular overlaps and hence to states of infinite potential energy.Even when the potential does not have a hard core the effect of the approximation is a large and spurious contribu-tion to the free energy in mixtures of different size. In fact M a n ~ o o r i ~ ~ and others60i65 have been able to show that for conformal mixtures the random-and axi. 5 4 I. Prigogine A. Bellemans and A. Englert-Chowles J . Chem. Phys. 1956 24 518. 5 5 I. Prigogine 'The Molecular Theory of Solutions' North-Holland Amsterdam 1957. " W. Byers Brown Phil. Trans. Roy. SOC. 1957 A250 175. '' W. Byers Brown Phil. Trans. Roy. SOC. 1957 A250 221. s g W. Byers Brown Proc. Roy. SOC. 1957 A240 561.5 9 Z. W. Salsburg and J. G. Kirkwood J . Chem. Phys. 1952 20 1538. '' R. L. Scott J . Chem. Phys. 1956 25 193. '' Z. W. Salsburg P. J. Wojtowicz and J. G. Kirkwood J . Chem. Phys. 1957 26 1533. '' P. J. Wojtowicz Z . W. Salsburg and J. G . Kirkwood J . Chem. Phys. 1957 27 505. " A. Bellemans V. Mathot and M. Simon Adv. Chem. Phys. 1967,11 117. 6 4 G. A. Mansoori J . Chem. Phys. 1972 57 198. ' 5 R. M. Mazo J . Chem. Phys. 1964,40 1454 Mixtures of Simple Liquids 87 mixing approximation provides an upper bound on the free energy of the real system. The defects inherent in the assumption of random mixing are only partially overcome by the introduction of the approximation (13) and use of the Average Potential Model also results in an unrealistically large positive contribu-tion to the free energy of mixing except in cases when the molecules are nearly equal in size.Neither the random-mixing approximation nor the Average Poten-tial Model can be usefully applied to hard-sphere mixtures. A more accurate description of mixtures is obtained by supposing that the g&) are functions which are related to each other on a corresponding-states basis. Specifically it is assumed that (1 5 ) sll(r/%) = S12(1/612) = g22(dc22) = g,(r/g,) say It is clear that this approximation takes into account the ordering effects of size differences. In the case of conformal mixtures equation (15) can be shown to lead to a prescription for &,a in a one-fluid theory. In order to define the equi-valent substance uniquely a further expression is required.By applying equation (15) to the case of hard spheres at contact an expression may be derived for d,, the diameter of the hard spheres in the equivalent hard-sphere system in terms of the d i j . It is then assumed that the same functional relationship holds between a and aij. This approximation is called the one-fluid van der Waals model because the mixing rules for E and ox are a modem version of van der Waals’ pro-posal for the calculation of the parameters in his equation of state for mix-tures.66-68 A two-fluid van der Waals follows if it is assumed by analogy with equation (13) that g12(r/012) = 3[Sll(Y/alJ + gz2(r/a22)1 (16) The whole question of one-fluid theories has recently been discussed by Srnith6’v7’ from the point of view of the conformal solution theory of Longuet-Higgins and Byers B r ~ w n .~ ” ~ ~ The basis of conformal solution theory is the expansion of the Helmholtz free energy of the mixture about that of a pure reference fluid which is taken to be conformal with the components of the mix-ture in powers of some suitably chosen expansion variable. Let the pair potentials in the mixture and in the reference fluid be characterized respectively by para-meters qj aij and E’ no. In order to maintain maximum generality Smith69 6 6 T. W. Leland P. S. Chappelear and B. W. Gamson Amer. Inst. Chem. Engineers J . , 6 7 6 a T. W. Leland J. S. Rowlinson and G. A. Sather Trans. Faraday SOC. 1968,64 1477. 69 W. R. Smith Canad. J . Chem. Eng. 1972 50 271. ’O W. R. Smith Mol. Phys. 1971 22 105.’’ H. C. Longuet-Higgins Mol. Phys. 1958 1 83. 72 W. Byers Brown and H. C. Longuet-Higgins Proc. Roy. SOC. 1951 A200,416. 1962 8 482. R. C. Reid and T. W. Leland Amer. Inst. Chem. Engineers J. 1965 11 228 88 I. R. McDonald chooses to make the expansion in powers of a = ~ ’ d and b = ~ ‘ c . 9 and finds that A = A + NkTCxiInxi 1 + RL2) c xixJaij - a,) + R r ) c xix,(bij - b,) + higher-order terms i j i j where A is the free energy of the reference fluid. The coeficients Ri2) and Ri2) involve integrals over the pair distribution function of the reference system ; the higher-order terms become rapidly more complex and even the second-order terms involve integrals over the three- and four-body distribution functions. In order to make use of this result it is necessary to choose both a reference fluid and a set of values for p q r and s.The first-order term in equation (17) was originally derived by L~nguet-Higgins~’ who chosep = 1 s = 3 q = r = 0. This choice makes it possible to express the coefficients Ri2) and R f ) in terms of thermodynamic functions of the reference system which Longuet-Higgins took as being one of the pure components. The same choice of the reference fluid but with p = s = 1 4 = r = 0 has been made more recently by Tan and L ~ k s . ~ ~ These authors succeeded in evaluating the second-order terms in equation (17) by re-writing the most complicated coefficients in terms of the density and tem-perature derivatives of the pair distribution function. However the use of one pure component as the reference system or of any reference system which is independent of concentration means that the perturbation cannot be small at all composition^.^^ A better choice of reference system is one which annuls the first-order terms in equation (17).This requires that E and 0 be chosen such that Conformal solution theory therefore leads naturally to a one-fluid theory of the corresponding-states type. In first order the properties of the mixture (apart from the ideal free energy of mixing) are those of an equivalent pure substance with a pair potential characterized by the parameters .c0 and 0,. Different choices for p 4 r and s correspond to different mixing rules. For example, p = r = 1 q = 6 s = 12 is the random-mixing approximation for 12-6 potentials and p = 1 r = 0 4 = s = 3 is the van der Waals model.The higher-order terms in equation (17) are corrections to the particular one-fluid theory which is adopted. 7 3 P. Y. Tan and K. D. Luks J . Chem. Phys. 1970 52 3091. 7 4 D. Henderson and P. J. Leonard Proc. Nut. Acad. Sci. U S A . 1971,68 2354 Mixtures of Simple Liquids 89 5 Perturbation and Variational Theories A notable feature of recent theoretical work on liquids has been the development of a number of very successful perturbation methods for the calculation of equili-brium properties. Two of these due to Barker and Henderson and to Mansoori and Canfield have also been used to calculate the excess thermodynamic pro-perties of mixtures again with considerable success. 76 the Helmholtz free energy is expanded about that of a system of hard spheres.There are two principal reasons for choosing hard spheres as the reference system in a perturba-tion treatment. First it is known that the structure of real simple liquid is similar to that of a hard-sphere fluid because the structure is largely determined by the repulsive part of the pair potential. Secondly the equation of state and pair distribution function for the hard-sphere system are available either from machine calculations or from approximate analytical theories. The extension of the theory to the problem of mixtures77y78 may be made in two ways correspond-ing to two different choices for the reference system. Either a single-component hard-sphere fluid or a mixture of hard spheres may be used. The former is required for the treatment of hard-sphere mixtures and yields results in good agreement with computer experiment^^^ but proves unsatisfactory when used for mixtures of 12-6 molecules; only the latter choice will be discussed here.Let cpiJr) be the true pair potentials in the mixture. The starting point of the Barker-Henderson method is the introduction of a set of modified potential functions t,biJr) which are related to the functions cpiJr) in the following way : exp [ - t,biJr)/kT] = 1 - H(d + xij - Rij) exp [ - q i l d i j + xij)/kT] In the Barker-Henderson theory of one-component + H(d, + xij - Rij) + H(r - dij) ( ~ X P [-yijqij(r)/kTI - 11 (19) where xij = (Y - dij)/aij d is the hard-sphere diameter clij varies the steepness of the potential in the repulsive region yij varies the depth of the potential in the attractive region and H ( x ) is the Heaviside step function defined by H(x) = 0 x < 0 = 1 x > o In the case of 12-6 potentials it is convenient to set Rij = aij though this choice is not essential.When aij = yij = 0 the potential t,bijr) becomes the potential for hard spheres of diameter d i j ; when ctij = y i j = 1 $ij(r) is identical to cpiJr). 7 5 J. A. Barker and D. Henderson J. Chem. Phys. 1967,47 2856. 7 6 J. A. Barker and D. Henderson J. Chem. Phys. 1967,47 4714. 7 7 D. Henderson and J. A. Barker J. Chem. Phys. 1968 49 3377. P. J. Leonard D. Henderson and J. A. Barker Trans. Faraday SOC. 1970 66 2439 90 I. R. McDonald The Helmholtz free energy of the mixture of interest may now be expanded in powers of aij and yij.The first-order result is ( A - A,)/NkT = 271p C xixi[ - aij - d$gijo(dij){dij - 6,) i j where the subscript zero is used to denote properties of the reference system and 6 = { 1 - exp [ - qijz)/kT]) dz j:" As the parameters d and d, are arbitrary it is convenient to choose them in such a way as to annul the terms in a and a, on the right-hand side of equation (21) i.e. d = a, d, = a,. Setting aij = y i j = 1 for all i andj the final result becomes ( A - A,)/NkT = -4np c xix,d;gijo(dij)[dij - 6,] i > j + 271(P/k~) 1 xix,Sm qijr)gijo(r)r dr (23) i j R i l In applications to binary mixtures of this version of the theory the Percus-Yevick results for gij,(r) have been used to evaluate A from equation (23). As these results were obtained under the usual assumption of additivity of diameters it follows that d, cannot be chosen to annul the a,,-term.A method which is probably more accurate is to use a non-additive hard-sphere mixture [i.e. a system for which d # $ ( d + d,,)] as a reference fluid. Unfortunately there are no Percus-Yevick or simulation results available for such mixtures so this approach cannot be exploited at present. In the first published series of calculations for mixtures of 12-6 liquids Leonard, Henderson and Barker78 used for A an expression obtained by adding the excess properties calculated by the Percus-Yevick theory to the properties of an ideal mixture of hard spheres. The properties of the two components in the ideal mixture were obtained from the Pad6 approximant to the hard-sphere equation of state which has been proposed by Ree and Hoover.79 However it is now known that use of this procedure gives rise to appreciable errors in the calculated excess properties and more accurate results are obtained" when A, is derived from the equation of state of Mansoori et u I .~ ~ equation (10) of this review. The variational theory of Manssori and Leland". 82 is an extension to mixtures of the work on pure fluids by Mansoori and G~nfield.~~ The starting point is 7 9 F. H. Ree and W. G. Hoover J . Chem. Phys. 1964,40,939. E. W. Grundke D. Henderson J. A. Barker and P. J. Leonard Mol. Phys. in the press. G. A. Mansoori and T. W. Leland J . Chem. Phys. 1970,53 1931. G. A. Mansoori J . Chem. Phys. 1972,56 5335.83 G. A. Mansoori and F. B. Canfield J . Chem. Phys. 1969,51,4958 Mixtures of Simple Liquids 91 an inequality which relates the Helmholtz free energy of a system of interest, which may be referred to as the real system to that of a reference system. This inequality has the form The subscript zero is again used to denote properties of the reference system and the subscripted angular brackets denote an expectation value for states of the reference system. In the case when the real system is a binary mixture the reference system is taken as a mixture having the same composition. If the reference system is characterized by pair potentials qijo(r) and the mixture of interest by pair potentials qi,(r) the inequality (24) may be written in terms of gijo(r) the pair distribution functions in the reference system in the form A < A + 2nNp 1 xixj (25) i j where In all applications of the variational method to mixtures of 12-6 liquids which have been reported up till now the reference system has been taken to be a mixture of additive hard spheres with diameters d and d, .An approximation to the free energy of the real system is then obtained by minimizing the right-hand side of (25) with respect to simultaneous variations in d and d, . This minimization is most conveniently achieved by reformulating the inequality in terms of the Laplace transforms of the hard-sphere pair distribution functions for which analytical relations have been derived33 from the solution of the Percus-Yevick equation. For a specified set of conditions (temperature density intermolecular potential parameters and mole fractions) in the ranges so far studied only one relative minimum is found for the right-hand side of (25).The optimum values of d and d, for a given mixture vary only very slowly with composition. The Helmholtz free energy of the reference system is again most reliably determined from the semi-empirical equation of state equation (10). 6 Comparison Between Theory and Experiment Values of the excess properties of a number of real mixtures which are predicted by the various theories discussed in this review are shown in Table 1. Comparison with the Monte Carlo results which are also listed in Table 1 reveals the in-adequacy of both the random-mixing approximation and the Average Potential Model.On the other hand there is a high correlation between the signs of the excess properties of the real systems and the predictions of these two theories. This fortuitous agreement emphasizes the fact that comparison between theory and laboratory experiments on real mixtures is at best of limited value and may indeed be misleading. In the present case for example a measure of agreement is obtained because errors arising from a spurious positive contribution to th 92 I. R. McDonald free energy of mixing of molecules of differing sizes are partially offset by the neglect of departures from the geometric-mean (Berthelot) rule. The other theories are very much more satisfactory. They are all in agreement with the Monte Carlo results in predicting that VE is invariably negative but that GE and HE may have either sign.From the results given in Table 1 it is difficult, however to draw any firm conclusions regarding the relative accuracy of the different theories and more interest is attached to a systematic study over a range of intermolecular parameter ratios. The results of such a survey are displayed in Figures 1-9. Examination of these graphs leaves no doubt that perturbation theory and variational theory are both reEarkably successful in accounting for the excess properties of mixtures of simple liquids. Not surprisingly bearing in mind their basic similarity the two approaches yield results in broad agreement with each other; variational theory appears to yield slightly more accurate values for GE and HE but perturbation theory is more successful in the prediction of VE.However it is also true that the good results for the excess properties are to some extent the consequence of a canceIlation of large errors Figures 10 and 11 show that neither theory is able to predict accurately the total properties of either the pure components or the mixture. Figures 1-9 show also that the van der Waals one-fluid model is clearly superior to the more sophisticated two-fluid version. The one-fluid theory works well over a moderately wide range of parameter ratios but under extreme conditions large errors occur; this is particularly noticeable in the case of VE. The parameter range for which the theory gives good results is sufficiently wide to include all the real systems listed in Table 1 with the exception of CH + CF,.200 0 I I I I 0 9 1 0 1 1 a1 1 012 -Figure 1 GE as a function of 01,/o12 for an equimolar mixture of 12-6 liquids ur 97 K and zero pressure (EIZ/k = 133.5 K t s 1 2 = 3.596 A k = 1.0).'* The points show the results of Monte Carlo calculations and the curvesgive the predictions of various theories: Barker-Henderson perturbation theory (solid curve) variational theory (broken curve), and the van der Waals one-Jluid model (dot-dash curve) The curves are labelled with the appropriate value of E~ 1 / ~ Mixtures of Simple Liquids 300 I w t 200 100 0 93 0 -200 I I I I I I 0.9 1.0 1.1 ‘1 1 QI 2 -Figure 2a as a function of crl ]/a for an equimolar mixture of 12-6 liquids at 97 K and zero pressure.For other details see caption to Figure 1. (The variational results are omitted for the sake of clarity) 0.9 10 1.1 a1 1 -‘17 Figure 2b See caption to Figure 2 94 I. R. McDonald I I I 0.9 1 .o 1.1 Figure 3 V E as a function of a1 l/a12 for an equimolar mixture of and zero pressure. For other details see caption to Figure 1 400 300 w u 100 0 I I I I 0.92 0.96 1.0 1.01 1.08 1 2-6 liquids at 97 K Figure 4 GE as a function of c1 ,/al for an equimolar mixture of 12-6 liquids at 115.8 K and zero pressure (El2/k = 141.4K a12 = 3.59& k, = 1.0).*' The points and the curves have the same meaning as in Figure 1. The curves are labelled with the appropriate value of E ,/ Mixtures of Simple Liquids 95 1=115.8 K -100 0 92 0 96 10 1.04 1.08 Figure 5 HE as a function of c1 Jc12 for an equimolar mixture of 12-6 liquidr at 115.8 K and zero pressure.For other details see caption to Figure 4 O t 1.00 I m - 3 -I 0.92 0.96 10 1 OL 1.08 01 I 612 -Figure 6 VE as a f i c t i o n of o1 Jal2 for an equimolar mixture of 12-6 liquids at 1 15.8 K and zero pressure. For other details see caption to Figure 96 I . R. McDonald 300 200 W u 0 -100 0 9 10 1 011 012 -Figure 7 GE as a function of 0 ,lo for an equimolar mixture of 12-6 liquids at 1 11 K and zero pressure (E12!k = 133.5 K c12 = 3.596 A k, = LO).*' The double dot-dash curve shows the predictions of the van der Waals two$uid model and the points and other curves have the same meaning as in Figure 1. The curves are labdled with the appropriate value of 1 / ~ 1 2 4 00 200 .W a 0 -200 0 9 1 0 1.1 011 012 -Figure8a as a function of ( ~ ~ ~ / u ~ ~ for an equimolar mixture of 12-6 liquids at 117 K and zero pressure. For other details see caption to Figure Mixtures of Simple Liquids 200 1 Figure 8b See caption I r=117 'I -100 O 1. / I /' I I 1 I 0.9 1.0 1.1 u11 012 -to Figure 8a 0 - 1 I - 0 E - 3 97 -L I I I I I I 0.9 1.0 1.1 011 a12 -Figure 9 VE as a function of c1 JcI2 for an equimolar mixture of 12-6 liquids at 117 K and zero pressure. For other details see caption to Figure 7 A number of problems and possibilities remain. It would be desirable for example to place the van der Waals one-fluid model on a more satisfactory theoretical basis and to understand the reasons for its superiority to the two-fluid version. This should make it possible to improve the model in a natural way. Unfortunately there are limits to the applicability of any one-fluid theory 98 I. R. McDonald a2 0.L a6 0.8 1.0 1, Figure 10 Enthalpy as a function of composition.for the system Ar + Kr ut 116 K zero press~re.~' The triangles show the results of Monte Carlo calculations and curves give the predictions of the Barker-Henderson perturbation theory (pert) the variational theory (oar) and the and 361 33t A A A Mixtures of Simple Liquids 99 The reason for this may be understood by considering the equivalent substance in such a model as the reference system in a conformal solution theory. At some stage when the potential parameters for the pure components are sufficiently different it becomes necessary to include second-order terms in the free-energy expansion. Even if it is possible to evaluate these terms the theory has at this point lost the simplicity which is its most attractive feature. The incorporation of higher-order terms in a perturbation or variational treatment may prove to be a more profitable line of advance because the application of these methods is not limited to conformal mixtures

ISSN:0069-3022    

DOI:10.1039/GR9726900075

出版商:RSC    

年代:1972

数据来源: RSC

摘要:

4 The Magnetic Properties of Transition-metal Ions By R. C. SLADE Chemistry Department Queen Elizabeth College, Campden Hill Road London W8 7AH 1 Introduction The previous Report' discussed at some length the application of parameterized theoretical models to the magnetic behaviour of transition-metal complexes. The extraction of numerical values for the various parameters and the subsequent interpretation and correlation of these values with structure and bonding was seen to be the primary concern of most magnetochemical investigations. This concern remains the dominant theme of work published during the year covered by this Report. As before the Report is divided into three sections the first section covers the broad area of magnetically dilute compounds in which the magnetic properties are essentially determined by structural aspects and ligand types ; the second section is concerned with spin-spin exchange interactions and their influence on magnetic behaviour; and a third section is devoted to 'cross-over' situations.Among several reviews published during the year two will attract the attention of many magnetochemists. A timely review of the techniques used for measuring single-crystal magnetic anisotropies together with a survey of anisotropy measure-ments has been written by Mitra2 and the late J. s. Griffith discussed3 the general theory of the magnetic susceptibilities of polynuclear complexes as applied to two and three interacting spin systems. 2 Theoretical Models and Magnetic Behaviour The theoretical magnetic behaviour of complexes with a cubic field 2T2 ground term has been discussed in two papers.An explicit expression has been derived4 for the susceptibility of octahedral d' ions allowing for the spin-orbit mixing of the excited ' E term wi?h the ground term and also for the reduction in orbital angular momentum. The model is similar to that used previously' to discuss the behaviour of d9 ions in distorted tetrahedral complexes. It has been shown6 ' ' S. Mitra Transition Metal Chem. 1972 7 183. R. C. Slade Ann. Reports (A) 1971 68 61. J. S. Griffith Structure and Bonding 1972 10 87. A. D. Westland Canad. J. Chem. 1972 50 1468. M. Gerloch J. Chem. SOC. ( A ) 1968 2023. 0. Kahn and S. F. A. Kettle Theor. Chim. Acta 1972 27 187. 10 102 R. C. Slade that the influence of vibronic coupling on the temperature dependence of the susceptibilities of cubic complexes with T2 ground terms is similar to that of covalency.The magnetic properties of the 2q term are considered within a four-parameter model incorporating the spin-orbit coupling coefficient A the covalency parameter k the vibronic coupling coefficient x and h q the frequency of the doubly degenerate modes of vibration. The coupling of these vibrations with the electronic parts of the wavefunctions is treated by the Born-Oppenheimer approximation. The results of this model indicate that increasing values of x lead to less-marked temperature dependence of the magnetic moments and that increasing covalency (decreasing k ) has the same effect. However the reduction in the orbital contribution to the magnetic moment owing to vibronic coupling is dependent on temperature whereas the reduction due to covalency is not so that the effects although similar are not the same.The principal and mean magnetic moments of V(urea),I have been measured' over the temperature range 300-80 K and the data interpreted in terms of the Figgis model8 for the 3T1g ground term of the d2 ion. Values of the three para-meters corresponding to 'best fit' of experimental and calculated moments were 2 = 45 cm-' A = 450cm-' and k = 0.5. The possible affect of including the excited spin triplet terms in the model was discussed and it was suggested that there would be no drastic changes in the parameter values on going to the more complex model presumably because of the high value of A,, in this complex.An X-ray analysis shows the trigonal distortion to be slightly temperature dependent since the small trigonal angular compression which exists at room temperature becomes a small angular extension at 90 K. The magnetic properties of some dithiocarbamate complexes of chromium(rir), manganese(irr) and iron(1ir) have been measured from 300 K to below 4.2 K9 The chromium complex has a moment that is substantially independent of temperature falling from a value of 3.80 pB at room temperature to 3.61 pB at ca. 4 K ; similarly the manganese complex has a temperature-independent moment consistent with that expected for an octahedral d4 ion. On the other hand an iron complex has magnetic properties that cannot be accounted for on the basis of a zero-field-splitting of the ,A, ground state.Previous Mossbauer spectral'* and far-infrared Zeeman-effect' studies have suggested a value of D, the z.f.s. parameter of -3.08 K although this value is not consistent with the magnetic moments at low temperatures. Furthermore positive values of D give no better agreement and neither does the reported crystal-structure determination suggest a pathway for magnetic exchange.' The substituted ligand (Et,dtc), however forms a tris complex with iron(1n) which is low-spin with moments of 2.10 and 1.85 pB at 83 and 4.2 K respectively and which are interpreted in terms of a low-symmetry splitting of the 2T2g ground term of 350 cm-'. ' B. N. Figgis and L. G. B. Wadley J.C.S. Dalton 1972 2182. B. N.Figgis J. Lewis F. E. Mabbs and G. A. Webb J. Chem. SOC. ( A ) 1966 1411. B. N. Figgis and G. E. Toogood J.C.S. Dalton 1972 2177. G. C. Brackett P. L. Richards and W. S. Caughey J. Chem. Phys. 1971,54,4383. l o R. Rickards C. E. Johnson and H. A. 0. Hill J. Chem. Phys. 1968,48 5231. l 2 P. C. Healy and A. H. White J.C.S. Dalton 1972 1163 The Magnetic Properties of Transition-metal Ions 103 Single-crystal anisotropies and powder susceptibilities have been reported for dichlorotetrakis( thiourea)-iron(1r) and -manganese(u) over the temperature range 300-80 K together with powder susceptibilities down to liquid-helium tempera-ture13 and single-crystal polarized spectra for the iron complex. The results were interpreted within the D crystal-field model parameterized by Dq Dt Ds, and A previously used for the corresponding nickel(@ and cobalt(r~)complexes.' 4 9 l5 The parameter values obtained for the iron complex were ambiguous although the sign and magnitude of the anisotropy fixed the relationship that Ds and Dt have the same sign and that Ds - 1.8Dt approximate values being given by lDtl < ca.85 cm- '. The data for the manganese complex were interpreted using the 6S 4G and 4P free-ion states perturbed by a D crystal field and spin-orbit coupling. It was shown that the sign of the z.f.s. parameter is determined by the sign of Dt and that the sign of the magnetic anisotropy reflects the sign of D. Thus pI > plr if D > 0 implying that Dq(equatoria1 ligand) > Dq(axia1 ligand), and vice versa. The very small anisotropies associated with the d5 configuration precludes any accurate determination of the parameter values but for Mn(tu),Cl, it was found that p > pIl and hence Dq(thiourea) > Dq(ch1oride).Long-standing discrepancies in the sign of the molecular magnetic anisotropy of ferrous ammonium sulphate hexahydrate have been resolved by a study16 of the principal crystal anisotropies over the range 300-90 K. The relationships between the molecular and crystal properties allows a determination of the angle between the symmetry axes of the two magnetically inequivalent molecules in the unit cell and the (010) crystal plane. It was found that K > KII gives a closer fit to the X-ray crystallographic angle than the alternative sign of the anisotropy and calculated values of the principal moments agree with the experimental ones.Values of the orbital reduction parameter k can apparently exceed 1.0 in low-spin iron(Ir1) complexes' ' by virtue of the mixing-in of excited t i e configurations into the tl ground configuration. Following Thornley18 and Griffith,lg the mixing is considered to arise by electrostatic interactions and results in an increase in the effective orbital angular momentum of the ground term. The electronic properties of trans-[FeX(NO)(das),J+ and trans-[FeX,(das),J+ where X = C1 or Br and das = o-phenylenebis(dimethy1arsine) have been measured.20 The complexes have a single unpaired electron with moments of 2.31-1.81 pB at room tempera-ture. For trans-[FeBr,(das),] + the room-temperature moment of 2.24 pUB falls to 1.8 p at 4 K whereas for the chloro-complex the moment is 2.31 pB at the higher temperature and 2.12 pB at 77 K.These results are consistent with a spin-paired tgg electronic configuration for the iron(m) complexes and so the experimental M. Gerloch J. Lewis and W. R. Smail J.C.S. Dalton 1972 1559. l 4 M. Gerloch J. Lewis and W. R. Smail J. Chem. SOC. ( A ) 1971 2434. I s M. Gerloch P. N. Quested and R. C. Slade J . Chem. SOC. ( A ) 1971 3741. l 6 A. K. Gregson and S. Mitra Chem. Phys. Letters 1972 13 313. l 7 S. A. Cotton Inorg. Nuclear Chem. Letters 1972 8 371. l 8 J. H. M. Thornley J. Phys. (C) 1968 1 1024. l 9 J. S. Griffith Mof. Phys. 1971 21 135. 'O R. D. Feltham W. Silverthorn H. Wickman and W. Wesolowski Inorg. Chem. 1972, 11 676 104 R. C. Slade data were fitted to the Figgis model for the 2T2 term.21 The low-symmetry splitting for the bromo- and chloro-complexes is 750 and lo00 cm- ' respectively, and I is reduced by 5-10 %.The nitrosyl complexes have moments which cannot be fitted to this model and it was suggested that these complexes have rhombic rather than axial symmetry. The phase transition that occurs in (Et4N)2CoC14 has been studied by low-temperature 20-1.5 K magnetic measurements.22 The room-temperature crystal structure has two magnetically equivalent molecules in the unit cell with the unique molecular axes of the distorted COCI,~- ions lying along the crystal-lographic c axis. The low-temperature studies indicate that below the transition temperature the unique axes lie in or near to the (001) plane and that the tetragonal symmetry of the crystal is maintained.The principal and mean magnetic moments of Cs,CoX and (Et,N),CoX, X = C1 or Br have been measured,23 3&80 K and the results interpreted within the 4F-4P free-ion basis set per-turbed by a D, crystal-field and spin-orbit coupling. The crystal-field energy levels and z.f.s. of the 4A2 ground term are found to be insensitive to the value of Cp the second-order crystal-field radial parameter particularly for 8 < O,, . The best fits of the experimental data to this theoretical model give 8 values of 52-54', compared with the X-ray crystallographic angle of 106.0" for the Cl-Co-C1 angle (equal to 28) in Cs,CoCl,. The data for the tetraethylammonium complexes were independently fitted above and below the transition temperature assuming that the molecules remain axially distorted and slight changes in the effective distortion angle were found.However although 'perfect fits' to values may be found it is not possible to obtain even approximate values for Cp in thesemolecules because of the marked insensitivity of the eigenvalues and eigenfunctions of the 4F-4P manifold to this parameter. Room-temperature moments have been calculatedt4 for several low-spin cobalt(I1) complexes as functions of the energy separations between the ground term usually 2 A lg and various excited terms. Values for these energy separations taken from spectral data together with the spin-orbit coupling coefficient and a constant value of k2 equal to 0.8 allows the experimental moments to be repro-duced.The formation of paramagnetic cobalt(rr1) complexes is reported in two recent papers. An extensive in~estigation~~ of the complexes formed by metal ions and tricyclic quadridentate Schiff-base ligands derived from o-aminobenzaldehyde and various diamines has produced paramagnetic cobalt(rI1) complexes of the type [Co(L)X] where L is a nitrogen-donor ligand and X is C1- Br- or I - . Moments of 2.8-2.7 ,uB were reported and the complexes tentatively assigned a five-co-ordinate square-pyramidal structure. The paramagnetism was rational-ized in terms of a strong tetragonal distortion giving energetically similar dZ2 and 2 1 B. N. Figgis Trans. Faraday Soc. 1961 57 190. 2 2 J. N . McClearney G . E. Shankle R. W. Schwartz and R. L.Carlin J . Chem. Phys., 1972,56 3755. 2 3 M. Gerloch J. Lewis and R. Rickards J.C.S. Dalton 1972 980. 2 4 Y. Nushida and S. Kida Bull. Chem. SOC. Japan 1972 45 461. 2 5 B. M. Higson and E. D. McKenzie J.C.S. Dalton 1972 269 The Magnetic Properties of Transition-metal Ions 105 d, orbitals and hence an electronic configuration (xz)z(yz)2(xy)'(zz)'. A planar cobalt(rr1) complex 3-n-propylbiuretatocobaltate(111) has been reported26 as being paramagnetic with a room-temperature moment of 3.51 pB. It was also found that addition of donor amines to this complex gives octahedral diamagnetic compounds. An interesting paper2' on the magnetic and thermal properties 12&530 K, of bis-N-(3-methoxysalicylidene)isopropylaminenickel(11) has shown that four separate crystalline forms may be isolated.Complexes of the general type bis-(N-R-X-salicylidene)nickel(II) have been extensively studied" and the structures and magnetic properties have been correlated with the nature of the groups R and X. In the present study the two Crystalline forms previously isolated,29 called I11 and IV were found together with two new forms I and I1 ; supercooled liquid and glassy states were also obtained by quenching the molten complex. Phase 111 is obtained as brown crystals by recrystallizing the crude product material from methanol. It is paramagnetic with the nickel ions in tetrahedral environments. The susceptibility of this form decreases smoothly as the tempera-ture is raised until at ca. 440 K a discontinuity is observed as phase I is produced, which is also brown in colour and paramagnetic.On the other hand recrystal-lization from diethyl ether gives a green crystalline solid phase IV which is diamagnetic and with a square-planar structure. Heating this phase to ca. 350 K gives the paramagnetic form phase I. The crystalline phase I1 is obtained by holding the supercooled liquid at ca. 350 K for thirty minutes whereupon green crystals are formed. These are diamagnetic and like phase I crystals they may be obtained stable at room temperature by supercooling. The molten state itself has interesting magnetic properties in that a paramagnetic-to-diamagnetic transition occurs as the melt cools ; at the glass-transition temperature the transi-tion process is stopped and the glassy state corresponds to 26 % paramagnetism.Clearly in this very complex situation the factors determining the structural stabilities are very finely balanced. Magnetic susceptibility measurements have also been applied3' to a study of the paramagnetic-diamagnetic equilibrium in solution. The Quincke method for susceptibility measurements in solution was modified for use in magnetic titrations in which C-substituted ethylenediamines were added to nickel(@ solutions. It was found that increasing C-substitution results in an increase in the tendency to form diamagnetic bis-complexes rather than the paramagnetic tris-complexes formed with ethylenediamine and 1,2-propanediamine. This behaviour was attributed mainly to steric interactions between the more bulky substituents. Single-crystal polarized spectra electron spin resonance spectra and magnetic anisotropies have been measured3 for the eight-co-ordinate complex tetra-(6-aminohexanoic acid)copper(II) diperchlorate.A crystal-field model was used 2 6 J. J . Bour P. T. Beurskens and J. J. Steggarda J.C.S. Chem. Comm. 1972,221. 2 7 N. Arai M. Sorai and S. Seki Bull. Chem. SOC. Japan 1972,45 2398. '* R. H. Holm G. W. Everett jun. and A. Chakarvorty Progr. Znorg. Chem. 1966,7,83. 2 9 A. Takeuchi and S. Yama Bull. Chem. SOC. Japan 1969,42 3046. 30 G. R. Graybill J. W. Wrathall and J. L. Ihrig Znorg. Chem. 1972 11 722. 3 1 C. D. Garner P. Lambert F. E. Mabbs and J. K. Porter J.C.S. Dalton 1972 320 106 R. C. Slade to describe the electronic properties and the experimental data interpreted to establish values of Cp and Dq and the sequence of the one-electron orbital energies.The latter was found to be x y > x 2 - y2 > z2 > x z yz the same as previously r e ~ o r t e d ~ ~ . ~ ~ for CaCu(CH,CO,) ,6H,O and furthermore the crystal-field parameters are of similar magnitudes in the two complexes. It was concluded that the crystal-field model provides a good description of the behaviour of the energy levels in these copper(r1) complexes and that a reported angular overlap does not appear to account for the spectra of both complexes. The magnetic properties of some copper(I1) complexes of benzoxazole have been reported.35 The room-temperature moments are ca. 1.9 pB and the susceptibilities obey the Curie-Weiss law with small Weiss constants. The moment of dichloro-bis(benzoxazole)copper(II) was given as 1.97 pB in contrast to the previously reported value of 1.57 l(B.36 The scarcity of magnetic studies devoted to the 4d or 5d transition elements continues and only two studies are reported.The magnetic properties of some molybdenum(1v) complexes of the type Mo(chelate),X have been measured,37 where (chelate) = acetylacetone 8-hydroxyquinoline or N-substituted salicyl-aldimines and X = halide. The room-temperature moments are ca. 2.7-2.6 pB, similar to those found for other molybdenum(1v) and the tempera-ture-dependence studies on Mo(sa1-N-Et),Cl and Mo(sal-N-C6H4Me-p),C12 were discussed in terms of the 'TIg ground term perturbed by an axial crystal field and spin-orbit coupling. Comparable magnetic behaviour has been reported39 for two tungsten(1v) complexes WCl,(PEtPh,) and WC14(PBun2Ph) which have room-temperature moments of 2.06 and 2.02 pB respectively.Rather more information is available for the 4fand 5fions. The principal and mean moments of the twelve-co-ordinate D, complex Ce,Mg,(NO,) ,24H20 have been measured4' at 300-80 K. Twelve- and six-co-ordinate crystal-field models incorporating the orbital reduction parameter were applied in calcula-tions of the moments and the g-values and the parametric variations of ,u 11 pl gll , and g were examined. Best fits were used to obtain values of the crystal-field parameters p 2 p4 and p6 of ca. 450 100 and 50-100 cm- respectively for k values of 0.96-4.93. The reduction in k was suggested to be most probably due to covalent mixing of the 4forbitals with ligand a-orbitals although the possibility of metalf-p orbital mixing was not discounted.In a continuing series on the magnetic properties of the lanthanide elements the principal and mean moments 32 F. E. Mabbs and W. R. Smail J . Chem. SOC. ( A ) 1970 1716. 3 4 D. W. Smith J . Chem. SOC. ( A ) 1971 1209. 35 3 6 E. J. Duff and M. N. Hughes J . Chem. SOC. ( A ) 1968 2144. 37 A. van den Bergen K. S. Murray and B. 0. West Austral. J . Chem. 1972 25 705. 3 8 B. N. Figgis and J. I ewis Progr. Znorg. Chem. 1964 6 123. 39 A. V. Butcher J. Chatt G. J. Leigh and P. L. Richards J.C.S. Dalton 1972 1046. 40 C. D. Garner P. Lambert and F. E. Mabbs J.C.S. Dalton 1972 91. G . Gliemann and P. Morys Z . phys. Chem. (teipzig) 1970 243 28 1. G.J. Hamilton and E. Kokot Austral. J . Chem. 1972 25 2235 The Magnetic Properties of Transition-metal Ions 107 of several hexakis(antipyrine)metal(III) tri-iodide complexes were reported for the metals praseodymium:' europium,42 dyspro~ium:~ holmium,44 and thulium45 (antipyrine is 2,3-dimethy-1-phenyl-A3-pyrazolin-5-one). In all cases a crystal field of DJd symmetry parameterized by the integrals p2 p4 and p6 and the effective distortion angle 8 was applied to the relevant free-ion states corrected for the effects of intermediate coupling. The ground state together with the lowest-lying excited states are shown to provide a satisfactory restricted basis set for the calculation of magnetic properties and these models were thus used to interpret the experimental data.Values of the crystal-field parameters were obtained from fitting procedures although in some cases only approximate ranges of some parameters were found. The magnetic properties of several compounds of uranium(1u) have been r e p ~ r t e d . ~ ~ ~ ' The room-temperature moments of ca. 3.3-3.0 pB decrease to ca. 2.8-2.6 pB a t liquid-nitrogen temperatures. Adducts of uranium tetra-chloride and tetrabromide with various amines have been prepared and character-ized by spectral and magnetic measurement^.^^ Room-temperature moments of 2.8-2.6 pB were reported together with variable-temperature data for (Et4N)4[U(NCS)8] and K,[U(NCS),]. The non-linear variation of the suscepti-bility with temperature for the tetraethylammonium complex was interpreted as evidence of a strong second-order Zeeman effect the moment being close to the spin-only value and not varying much with temperature.In contrast the potas-sium salt has a lower moment at room temperature and the variation with temperature is greater. These differences were attributed to changes in the second-order paramagnetism arising from small changes in the structure of the anion. The relationships between magnetic properties and structure are nicely illustrated by the prediction of possible site symmetries from magnetic data for some uranium(1v) and neptunium-(111) and -(Iv) complexes with the cyclopenta-diene ion.49 The magnetic susceptibilities 100-2.5 K were correlated with the properties of the crystal-field energy levels in fields of various symmetries. For example the complex U(Cp) has a moment of 2.76 pB up to 25 K whereas above 60 K the susceptibility becomes independent of temperature.This behaviour is consistent with a magnetic ground state lying some 3 0 c m - ' below an excited singlet state and hence with a crystal field of symmetry less than tetrahedral but with a three-fold axis i.e. C, or C . 4 1 M. Gerloch and D. J. Mackey J.C.S. Dalton 1972 410. 4 2 M. Gerloch and D. J. Mackey J.C.S. Dalton 1972 42. 4 3 M. Gerloch and D. J. Mackey J.C.S. Dalton 1972,415. 44 M. Gerloch and D. J. Mackey J.C.S. Dalton 1972 1555. 4 5 M. Gerloch and D. J. Mackey J.C.S. Dalton 1972 37. 46 R. Barnard J. I . Bullock and L. F. Larkworthy J.C.S. Dalton 1972 964. 4 7 R. Barnard J. I. Bullock B. J. Gellatly and L. F. Larkworthy J.C.S.Dalton 1972, 4 8 4 9 1932. P. Gans and J. Marriage J.C.S. Dalton 1972 1738. D. G. Karraker and J. A. Stone Inorg. Chem. 1972 11 1742 108 R. C. Slade 3 Spin-Spm Interactions A great deal of interest continues to be shown in polynuclear metal complexes exhibiting spin-spin exchange interactions. The theoretical models used to in-vestigate these systems lead to values of J the exchange integral and many workers hate attempted empirical correlations between the sign and magnitude of J and molecular structure nature of bridging ligands metal-metal separations, etc. These studies although rationalizing the magnetic behaviour of individual complexes do not suggest general methods of tackling exchange problems in a wide variety of complexes. For general problems the review by Griffith3 is of interest as well as a paper concerned with the interaction of four metal ions with orbitally non-degenerate ground states.” The magnetic properties of complexes containing the Ti2Clg3- anion have been interpreted” using the dipolar coupling model.In addition to the exchange interaction the result of distortion and spin-orbit coupling was considered for the individual 2qf ground terms. The separate effects were parameterized by: J, the exchange interaction between orbitals Q and b of the two atoms; 6 the crystal-field axial distortion of the ground terms; and [ the one-electron spin-orbit coupling coefficient. Numerical values of these parameters were varied and the eigenfunctions and eigenvalues of the 2T2-2& interaction plus Zeeman effect were calculated.The experimental momentss2 of (Et2NH,)Ti2C1 were found to be reproduced by values of [ = !50cm-’ 6 = 500cm-’ and J = - 300 cm- ’. The exchange integral in this case corresponds to the interaction when each electron occupies a tzr orbital of the trigonally quantized d-orbital set. Oxovanadium(1v) carboxylate complexes have susceptibilities which are low in comparison with many other oxovanadium(1v) compounds and which rise to maxima at 250-200 KS3 The Ising anisotropic exchange model was found to give a good description of this behaviour with J values of CQ. - 170 cm-’ and g = 2.1-1.9. These data together with some spectroscopic results were inter-preted in terms of a V=O-*.V=O interaction with additional interaction via bridging carboxylate groups.The oxovanadium(1v) ion has been showns4 to form polynuclear complexes with N-(2-hydroxyphenyl)-2-hydroxynaphthalidene-imines. Several of these complexes are antiferromagnetic with moments less than 1.73 pB and the interaction was suggested to arise by direct a-type overlap of the metal d, orbitals assuming that the configuration about each vanadium atom is a distorted square pyramid. Pure samples of p-0x0-bis[pentammine chromium(rrr)] halides have been prepared by a low-temperature procedure and the magnetic properties ~tudied.’~ 5 0 J. S. Griffith Mol. Phys. 1972 4 8 3 3 . C. G. Barraclough and A. K. Gregson J.C.S. Faraday 11 1972 68 177. 5 2 P. C. Couch G. W. A. Fowles and R. A. Walton J . Chem. SOC. ( A ) 1969,972. 5 3 A. T. Casey B.S. Morris E. Sinn and J. R. Thackeray Austra!. J . Chem. 1972 25, 1195. 5 4 G. 0. Carlisle and D. A. Crutchfield Znorg. Nuclear Chem. Letters 1972 8 443. 5 5 E. Pederson Acra Chem. Scand. 1972 26 3 3 3 The Magnetic Properties of Transition-metal Ions 109 The failure of previous investigator^^^-^* to obtain consistent results for studies of the magnetic properties of basic rhodo-salts of chromium(Ir1) has been attri-buted to preparative difficulties and the probable contamination with basic erythro-salts. For the pure complexes the magnetic behaviour 300-50 K is reproduced by the dipolar coupling model for two interacting high-spin chrom-ium(m) ions to give J values of ca. -450 a-' whereas pure erythro-complexes have J values of -23 cm-' when fitted to the same model.The possibility of explaining the magnetism in terms of the coupling of low-spin chrornium(II1) ions (strong tetragonal distortion acting on the octahedral t, orbitalss9) was investigated but although the room-temperature moments could be reproduced the temperature dependence could not. An ,,X-ray investigation has shown hydroxo-bridges in the complex di-p-hydroxo-tetraglycinatodichromium(II1) and the magnetic susceptibility was measured from 100 to 4.2 K 6 0 The data were described by the Van Vleck expression for exchange coupled high-spin chromium-(111) ions and best fits gave 2J = - 8.4 cm-' with g = 1.95. The complex di-p-oxo-tetrakis-(2,2'-bipyridine)dimanganese(111,~~ perchlorate trihydrate contains manganese in different oxidation states61 bridged by two oxygen atoms.The moment of 1 . 7 9 ~ ~ per manganese at room temperature decreases to 1.33 pB at 80 K and the susceptibility varies with temperahre in a way consistent with a superexchange coupling between the d3 and high-spin d4 ions. Magnetic exchange interactions. between pairs of similar and dissimilar metals have been studied6 in the dinuclear complexes Cu(TSB)MCl where M = manganese(II) iron(m) or COP~~X~II) TSB is a Lridentatezchiff base and n = 2 or 3. The Cu-Mn and Cu-Fe complexes have temperature-dependent moments and J values of - 24 and - 55 cm-' respectively and were obtained by fitting the data to the dipolar coupling model. The Cu-Cu complexes also exhibit pairwise antiferromagnetic interactions and the susceptibilities are described by the Bleaney-Bowers equation with J values of ca.-200 to - 100 cm-'. The magnetic properties of p-0x0-bis[protoporphyrin IX dimethyl ester iron(~~r)] 293-1.5 & were i n t e r ~ r e t e d ~ ~ in terms of a dimeric model with strong antiferromagnetic exchange between the high-spin iron(n1) ions. Using the dipolar coupling model a J value of 380 K was obtained and a comparison with the J values obtained for related compounds suggested an Fe.-O.Fe linear 5 6 H. Kobayashi T. Haseda E. Kanda and M. J. Mori J. Phys. SOC. Japas 1960 15, 1 646. A. Earnshaw and J. Lewis J. Chem. SOC. 1961 396. International Conference on Co-ordination Chemistry' Uppsala 1962 p. 50. 1962 p. 102. P. M. Plaksin R. C. Stoufer M. Mathew and G. J. Palenik J. A m v . Chem. SOC. 19?2, 94 2121.* B. Jezowska-Trzebiatowska and W. Wojciechowski in 'Proceedings of the VIIth 5 9 C. J. Ballhausen 'Introduction to Ligand Field Theory' McGraw-Hill New York, 6 o D. J. Hodgson J. T. Veal and W. E. Hatfield J. Coordination Chem. 1972 2 1 . 6 1 6 2 S. Kokot C. M. Harris and E. Sinn Austral. J. Chem. 1972 25 45. 6 3 T. H. Moss H. R. Eillienthal C. Moleski G. A. Smythe '2. C. McDaniel and W. S. Caughey J.C.S. Chem. Comm. 1972,263 110 R. C. Slade bridging unit in this complex. Halogeno(quinolin-8-olato)iron(111) complexes have moments below the spin-only value at room temperature and which decrease markedly with temperat~re.~~ The susceptibilities were fitted to the dipolar coupling model for two interacting iron(rr1) ions to give negative J values. The interpretation of these data was substantiated by Mossbauer studies and it was suggested that the metal ions were bridged by halogen or oxygen atoms.Magnetic and spectroscopic properties of the 0x0-bridged iron(II1) dimers in complexes of the type (enH,) [(FeHedta),0],6H20 have been rep~rted.~' The susceptibilities were fitted to the isotropic Heisenberg exchange model and, although it was not possible to distinguish between coupled 3 spins or coupled 3 spins with J values of ca. -95 cm-' it was clearly shown that the spectral data were consistent only with the former alternative. The spin-spin coupling model for this system was suggested to be more appropriate for describing the magnetic properties than the alternative three-centre delocalized molecular-orbital model of Dunitz and Orge1.66 Tetrahedral dinuclear cobalt(I1) complexes Co,LX where L = phthalazine or pyrazine ligands were reported67 and characterized by spectral and magnetic measurements.The magnetic behaviours were described by a model based on the antiferromagnetic coupling of the two high-spin cobalt@) ions6* and allowing also for the modification of the d-orbitals by covalency by use of a delocalization coefficient kZ. The experimental data were fitted to this model to give J values of ca. - 1.0 to -5.0 cm-' and k2 values of ca. 1.05 to 0.5. The values of these parameters were correlated with the electronegativities and nephelauxetic effects of the ligands X where X = Cl Br I or NCS. Preliminary results of magnetic susceptibility measurements have been reported6' for a series of di- and tri-nuclear complexes of cobalt(Ir) nickel@) and copper(@ with the ligand 1,7-diphenylheptane-1,3,5,7-tetraone.The cobalt complex was found to be trimeric with antiferromagnetic exchange the nickel complex was also a trimer but with strong ferromagnetic exchange and the copper complex exhibited inter- and intra-molecular exchange interactions. An investigation7' of some M(pyrazine),X complexes were M = cobalt(I1) or nickel@) and X = C1 Br, or I using vibrational spectroscopy and susceptibility measurements showed that the complexes have a sheet structure with bridging pyrazine groups between the metal ions and with trans terminal halogen ligands; previo~sly,~' they had been considered to have bridging halide atoms. The magnetic data of the nickel complexes together with those of Ni(pyridine),Cl and Ni(pyridine),Br were interpreted using the dipolar coupling model for a linear system and the pyridine 64 D.Cunningham M. J. Frazer A. H. Qureshi F. B. Taylor and B. W. Dale J.C.S. 6 5 H. J. Schugar G. R. Rossman C. G. Barraclough and H. B. Gray J. Amer. Chem. 6 6 J. D. Dunitz and L. E. Orgel J . Chem. SOC. 1953 2594. 13* A. Earnshaw and J. Lewis J. Chem. Soc. 1961 396. 6 9 B. Andrelczyk and R. L. Lintvedt J . Amer. Chem. SOC. 1972 94 8634. ' O M. Goldstein F. B. Taylor and W. D. Unsworth J.C.S. Dalton 1972 418. A. B. P. Lever J. Lewis and R. S. Nyholm J . Chem. Soc. 1964 4761. Dalton 1972 1090. SOC. 1972 94 2683. A. B. P. Lever L. K. Thompson and W. M. Reiff Inorg. Chem. 1972 11 104 The Magnetic Properties of Transition-metal Ions 111 complexes gave J values of + 6.6 and + 4.7 cm- respectively in agreement with the expected7 ferromagnetic interactions in systems with halogen-bridge bond angles of close to 90".However the pyrazine complexes were found to be virtually magnetically dilute and the very small J values were independent of the halogen atom. These data were claimed to support a linear Ni-pyrazine-Ni system and an antiferromagnetic exchange was predicted. The failure to observe any such exchange was attributed to some ferromagnetism arising from pyrazine n-orbital overlap with metal eg orbitals or by some unspecified metal-metal interaction. The magnetic susceptibilities of some dimeric nickel(@ ethylenediamine complexes [Ni,(en),X,]Y, where X,Y = C1,Br or X = NCS Y = I have been measured over the temperature range 3-1.5 K and also as a function of magnetic field strength.73 The moments are in the range for octahedrally co-ordinated nickel(@ ions at room temperature but on lowering the temperature the moments rise to ca.3.4 pB in the range 15-25 K and further cooling causes a rapid decrease in their values. This behaviour was interpreted in terms of a ferromagnetic intracluster interaction with exchange integrals of ca. 5-10 cm-together with a much weaker antiferromagnetic interaction between the dimers and/or a zero-field splitting of the ground terms of the individual nickel@) ions. The complex [Ni,(en),(NCS),]I represents the first example of a ferromagnetic-ally coupled nickel(I1) cluster involving polynuclear bridges ; also the magnitudes of the exchange integrals in these complexes are very similar despite large differ-ences in the Ni-Ni separations emphasizing that distance is no barrier to exchange provided that an efficient pathway is available.On the basis of magnetic and spectral data it was suggested74 that solid-state complexes of nickel(I1) with Schiff bases derived from 5-chloro-2-hydroxybenzophenone and ethylene-diamine contain both octahedral and square-planar nickel(1r) in the ratio 1 2, and a trimeric unit was used to account for the magnetic properties. Polynuclear Schiff base complexes have been formed75 by reaction of copper(@ or nickel@) nitrate with monomeric copper(I1) or nickel(I1) Schiff-base complexes. The copper series is dinuclear and shows moderately strong antiferromagnetic interactions with J values of ca.- 200 cm- obtained from the Bleaney-Bowers equation. The trinuclear nickel complexes however are essentially magnetically dilute although there is some slight indication of a weak ferromagneticinteraction. Polynuclear complexes of the copper(n) ion continue to be a rich source for magnetochemical studies and more papers have been devoted to this topic than to any other. Because of this relatively large number of publications some work is given only a cursory mention although readers are warned that longevity and significance are related only in the mind of the author. The sensitivity of exchange interactions to small changes in the geometry of 7 2 J. Kanarnori J.Phys. and Chem. Solids 1959 10 87. 7 3 A. P. Ginsberg R. L. Martin R. W. Brookes and R. C. Sherwood fnorg. Chem. 1972, 7 4 G . M. Mockler G. W. Chaffey E. Sinn and H. Wong Inorg. Chem. 1972 11 1308. '' J . 0. Miners. E. Sinn. R. B. Coles and C. M. Harris J.C.S. Dalton 1972 1149. 11 2884 112 R. C. Slade the bridging units has been shown76 for several antifcrromagnetic dinuclear copper complexes although an extensive e~amination~~ of a large number of copper carboxylate complexes using the singlet-triplet-singlet model suggests that variations in J (singlet-triplet separation) and A (singlet-singlet separation) are rationalized by the nephelauxetic effects of the terminal ligands rather than by tetragonality changes. The singlet-triplet-singlet model has also been applied78 to a series of dinuclear copper complexes with bridging aromatic N-oxide groups.For an extensive series of 1 1 complexes values of J of ca. - loo0 cm-' and A values of infinity were interpreted on the basis of a contribu-tion to J from a mainly superexchange mechanism rather than from an interaction between the d,2-y2 orbitals the b-bond together with little or no a-overlap of the metal d, orbitals. Pathways for the superexchange were discussed in terms of Cu-0 a-bonding with copper d, orbitals overlapping with oxygen a-orbitals in the assumed idealized C, distorted-square dimeric unit. A simple MO model has been applied7' to the exchange interactions in the dinuclear complex with the Schiff base derived from pyrrole-2-carbaldehyde and 3-aminopropanol and other oxygen-bridged dimers.Assuming D, symmetry for tlie four-membered-ring system Cu Cu the MOs transform as a, bzg, 2b,, and 2b3,. The first two are non-bonding and the latter two are mixed in the bonding and antibonding MOs. The energy separation between the antibonding b, and b3g orbitah was related to the exchange integral J and it was shown how the energies of these orbitals and hence the value of J was influenced by the 0-Cu-0 angle via overlap considerations and also by the bonding in the rest of the molecule. The first observation of a spin-triplet ground state for a metal amino-acid complex was reported for tetrakis-(L-tyrosinato)dicopper(Ir).*' The magnetic properties 93-2.5 K were fitted to a modified Langevin equation for interacting dimers and the triplet-singlet separation was found to be 19.1 cm-'.A mechan-ism involving out-of-plane a-orbital overlap was suggested to be compatible with the ferrornagnetism. Small variations in the Cu-0-Cu bond angles were suggested" as being responsible for the differences in the magnetic properties of di-ph ydroxo-bis-2 -(2-ethylaminoethyl)pyrid-nedicopper(11) perchlorate and simi-lar complexes. Two studies of the susceptibilities of [Cu(amine)(OH)],X have been reported for amine = 2,2'-bipyridylE2 and amine = 2,2'-bipyridyl or 1,lO-phenanthr~line.~~ The hydroxy-bridged dimers are weakly ferromagnetic for 0 / \ \ / 0 7 6 E. Sinn and W. T. Robinson J.C.S. Chem. Comm. 1972 359. 7 7 R. W. Jotham S. F. A. Kettle and J. A. Marks J.C.S. Dalton 1972 428. 78 R.W. Jotham S. F. A. Kettle and J. A. Marks J.C.S. Dalton 1972 1133. 7 9 J. A. Bertrand and C. E. Kirkwood Inorg. Chim. Acta 1972 6 248. J. F. Villa and W. E. Hatfield Inorg. Chem. 1972 1 1 1330. D. Y. Jeter D. L. Lewis J. C. Hempel D. J. Hodgson and W. E. Hatfield Inorg. Chcm., 1972 11 1958. J. A. Barnes D. J. Hodgson and W. E. Hatfield Inorg. Chem. 1972 11 144. 83 A. T. Casey Austral. J . Chem. 1972 25 231 1 The Magnetic Properties of Transition-metal Ions 113 X = $SO4 or I whereas for other anions zero or small negative J values were obtained. The exchange interactions in dimeric copper(I1) ad-dichloropropionate and its dioxan adduct have been studied ;84 room-temperature moments of 1.50 and 1.44 pB decrease with decreasing temperature and the susceptibilities obey the Bleaney-Bowers equation with 2J values of ca.- 250 cm-'. Bridging rn-phenyl-ene groups have been to give a very weak exchange interaction 2J = ca. - 1 .O cm - ' in di-~-NN'-m-phenylenetetrakis(salicylideneiminato)dicopper(II), where the copper ions are separated by 8.5A. Nitrogen atoms provide the bridging links in bis-(6-hydroxypurinato)copper(11) and bis-(6-aminopurinato)-copper(I1) complexes.86 These complexes resemble copper(@ acetate mono-hydrate in general stuctural properties and the susceptibilities may be fitted to the Bleaney-Bowers equation to give J values of ca. - 208 to - 156 cm- these values being only slightly lower than that for the acetate despite the appreciably longer copper-copper distance in the purine complexes. The interaction was considered to occur through a superexchange mechanism via the pn orbitals of the heterocyclic bridging ligands.The susceptibilities of four trinuclear copper(1r) complexes have been reported8' at 3 M . 2 K. The moments were compared with those calculated from a model based on a triangular array of copper ions with the central ion interacting with its neighbours on each side but with no interaction between these latter ions. The model is that previously ~ s e d ~ ~ * ~ ~ to interprete the liquid-nitrogen-temperature data for these complexes. This earlier work was confirmed and similar J were reported. A study of the susceptibilities 3 G 1 . 5 K of a group of tetrameric complexes cu4ox&4 where X = C1 L = (C,H,),PO and X = Br L = (C,H,),PO or C,H,N has been rep~rted.~' All complexes have moments of ca.1 . 9 2 ~ ~ at room temperature which rise to 2.3-2.1 pB at 40-65 K and then rapidly de-crease at lower temperatures. In these complexes the copper ions are arranged in a tetrahedron about the central oxygen atom and each copper ion has a trigonal-bipyramidal structure. It is argued that the 'normal' order of the d-orbital energy levels in trigonal-bipyramidal complexes found in say CuC1 -, may be altered significantly by the phosphine oxide or pyridine ligands so that an orbital doublet term becomes the ground state. The magnetic behaviour of four such ions coupled in a tetrameric unit was examined as functions of two exchange interactions the interaction between each pair of copper ions bridged by the central oxygen atom (parameterized by J 2 ) and the interaction through the bridging halogen atoms (parameterized by J1).The measured data were 8 4 8 5 D. Y . Jeter and W. E. Hatfield Znorg. Chim. Acfa 1972 6 440. 8 6 T. Asakawa M. Inoue K. Hara and M. Kubo Bull. Chem. Soc. Japan 1972,453,1054. " B. N. Figgis and D. J. Martin J.C.S. Dalton 1972 21 74. " S. J. Gruber C. M. Harris and E. Sinn J . Znorg. Nuclear Chem. 1968 30 1805. 8 9 S. J. Gruber C. M. Harris and E. Sinn J . Chem. Phys. 1968 49 2183. 90 M. E. Lines A. P. Ginsberg R. L. Martin and R. C. Sherwood J . Chem. Phys. 1972, M. Melnik Acta Chem. Scand. 1972 26 697. 57 I 114 R. C. Slade interpreted within this model to give values of J of ca. 28-45 K indicating a ferromagnetic exchange from bridging halides with near 90" bridge-bond angles and J values of ca.- 40 to - 67 K arising from an antiferromagnetic interaction via the .n-orbitals of the bridging oxygen. The crystal and molecular structure and susceptibility 3&90 K of tetrakis-[(aquo)(N-2-pyridylsalicylaldiminato)copper(11)] tetranitrate have been reported?' Although the molecule forms a tetrameric cluster with copper ions in an almost square arrangement the magnetic data are consistent with the Bleaney-Bowers equation for coupled dimers so that the cluster may be viewed as two independent dinuclear units. Some copper complexes with terdentate Schiff bases derived from substituted salicylaldehydes and S-methyl dithiocarbazate have been prepared.' The 5-nitrosal complex exhibits ferromagnetism with a moment of 2.03 pB at 293 K rising to 2.43 pg at 83 K.This behaviour was considered to be consistent with a cluster of tetrahedrally arrayed copper ions and a J value of +38cm-'. The antiferromagnetic exchange shown by Cu(NH,),CO has been inter-~ r e t e d ' ~ in terms of a direct interaction between the copper ions of neighbouring chains rather than by a superexchange through bridging carbonate groups and a modified Van Vleck equation94 gave a better description of the magnetic behaviour than the anisotropic Ising model for infinite chains the former giving a J value of -4.5cm-'. The failure to observe any appreciable spin-spin interaction in a-bis-(8-hydroxyquinolinato)copper(11) having a chain structure and the corresponding p form with a dimeric structure has been interpreted9' in terms of out-of-plane copper-oxygen distances of greater than 2.8A pre-cluding the transmission of the exchange.The susceptibilities of 2-(2-aminoethyl)-pyridine complexes of copper(I1) chloride or bromide have been measured, 296-2.8 K.96 Both CuLCl and CuLBr exhibit antiferromagnetism whereas the CuL,Br complex is paramagnetic. This behaviour is accounted for by the structures of the 1 1 and 2 1 complexes in that the latter has a five-co-ordinate structure of the [CuL,Br]+ ion with Cu-Cu separations of 11.858 along the chains and 7.41 A between the chains whereas the 1 1 complexes have dimeric structures with Cu-Cu separations of 3.9 A. For these complexes the Van Vleck equation for coupled dimers gives 25 values of - 5.7 and - 3.6 cm-' for the chloro- and bromo-complexes respectively.The complex polybis-[p-(2-picoline N-oxide)-chlorocopper(~~)-di-p-chloroldi-aquocopper(r1) dihydrate Cu,Cl,(C6H,NO) ,2H,O contains alternating linear chains of diamagnetic Cu,C1,(C6H,N0) units and paramagnetic CuCl ,2H,O groups linked by long copper-oxygen Measurements of the suscepti-9 1 9 2 9 3 D. Y. Jeter D . J. Hodgson and W. E. Hatfield Inorg. Chem. 1972 11 185. 94 9 5 G. W. Inman jun. W. E. Hatfield and R. F. Drake Inorg. Chem. 1972 11 2425. 96 D. Y. Jeter W. E. Hatfield and D. J. Hodgson J . Phys. Chem. 1972 76 2707. 97 H. Miyoshi H. Ohya-Nishiguchi and Y. Deguchi Bull. Chem. SOC. Japan 1972 45, J. Drummond and J . S. Wood J.C.S. Dalton 1972 365. M. Akbar Ali S. E. Livingstone and D. J. Phillips J.C.S.Chem. Comm. 1972,909. M. Inoue M. Kishita and M. Kubo Inorg. Chem. 1967 6 900. 682 The Magnetic Properties of' Transition-metal Ions 115 bility of this complex 300-1.6 K have shown that in the diamagnetic units the copper(1I)ions are so strongly coupled that the singlet state is almost totally populated whereas the CuCl ,2H,O units are magnetically dilute and the susceptibility obeys the Curie-Weiss law. This interpretation was supported by electron spin resonance spectral measurements showing a typical anistropic spectrum for the paramagnetic ion and a weak half-field resonance from the dimeric units. The antiferr~magnetism~~ observed by susceptibility measurements, 292-4.2 K for hexamminecobalt(uI) tribromodichlorocuprate(I1) has been suggested as arising from intermolecular exchange via the axial ligands of the trigonal-bipyramidal units.Out-of-plane copper-ligand interactions have been studied99 in dibromobis-(2-methylpyridine)copper(11) and its chloro-analogue. X-Ray structural data show that the molecules consist of weakly bound dimers with the individual copper ions bonded by trans bromines and nitrogen atoms in a basal plane with the bridging bromine atoms in the axial position of the square-pyramidal structure. The susceptibilities of both complexes were fitted to the Van Vleck equation for coupled dimers to give singlet-triplet separations of 5 and 7.4 cm- ' for the bromo- and chloro-complexes respectively. The Ising model for infinite linear chains was found"' to provide an acceptable inter-pretation of the antiferromagnetism of dichloro-(2,3-dimethylquinoxalinato)-copper(I1) and dichloro-(2-methylquinoxalinato)copper(11) with J values of - 45 and - 19 cm-'.Previous that the 2-methyl complex has chloride bridges compared with the quinoxaline bridges in the 2,3-methyl complex were supported by the relative magnitudes of these exchange integrals. Far-infrared spectral and magnetic susceptibility studies were found to be consistent with strongly interacting polymeric chains in complexes of pyrazine with copper(I1) halide~.''~ Both the Ising model for linear chains and the Bleaney-Bowers equation for coupled dimers gave acceptable fits to the measured data, although the infrared spectra were consistent with a polymeric structure. Mag-netic properties have been reported for dichloro(pyridazine)copper(II) and related compounds at 3 0 M .2 K ' O4 and for Cu(pyridine),Cl and Cu(pyridine),-Br at 297-8 K,'05 and the observed antiferromagnetism was discussed using the Ising and Heisenberg models. Finally some copper complexes of N-hydroxy-alkylsalicylideneimines were found to form paramagnetic or antiferromagnetic types106 of general formula Cu(sa1-N-ROH) or alternatively mainly ferro-magnetic complexes of the type Cu(sa1-N-RO). 9 8 D. Y. Jeter and W. E. Hatfield J . Coordination Chem. 1972 2 39. q 9 P. Singh D. Y . Jeter W. E. Hatfield and D. J. Hodgson Inorg. Chem. 1972,11 1656. D. E. Billing A. E. Underhill D. M. Adams and D. M. Morris J. Chem. SOC. ( A ) 1966, 902. l o * M. J. M. Campbell R. Grzeskowiak and F. B.Taylor J . Chem. SOC. ( A ) 1970 19. G. W. Inman jun. and W. E. Hatfield Inorg. Chem. 1972 11 3085. ' 0 4 S. Emori M. Inoue and M. Kubo Bull. Chem. SOC. Japan 1972,45 2259. D. Y . Jeter and W. E. Hatfield J . Inorg. Nuclear Chem. 1972 34 3055. T. Tokii Y . Muto M. Kato K. Imai and H. B. Jonassen J. Inorg. Nuclear Chem., 1972,34 3377. l o o G. W. Inman jun. J. A. Barnes and W. E. Hatfield Inorg. Chem. 1972 11 764 116 R. C. Slade 4 High-spin-Low-spin Equilibrium As a result of the close proximity of alternative ground-state energy levels, differing in spin multiplicity large variations in magnetic behaviour may be observed for small changes in structure or ligand type. Such variations in behaviour usually arise from the thermal equilibria between the ground states and they are often described as resulting from 'crossover' situations.In strongly distorted octahedral iron@) complexes it is possible that a 3 A , ground state is pr~duced.'~' Such a situation has been shown to exist in the complex [Fe(phen),(ox)],5H20 where phen = 1,lO-phenanthroline and ox = oxalate by magnetic susceptibility measurements down to 1.2 K and Mossbauer spectra at 4.2 K.'08 The complex has a room-temperature moment of 4.00 p B and its susceptibility obeys the Curie-Weiss law down to 77 K ; the moment is effectively constant down to 15 K when it then decreases rapidly to a value of 2.68 pB at 1.2 K. This behaviour is interpreted on the basis of a 3 A ground term with a zero-field splitting of 4.6 cm-' with the M = 0 level lowest. Magnetic properties associated with the TZg-'Alg crossover in iron@) have been reported for several complexes.The syntheses and magnetic properties of a series of complexes Fe(N-N-N),X where N-N-N = acr'a"-tri-imine-2,6-(dibenzothiazol-2-yl)pyridine have been described."' For X = C1 Br I or NCS the room-temperature moments are ca. 5.3 pB and they are independent of temperature as illustrated by the iodo-complex. These complexes thus contain high-spin iron(I1). However the perchlorate complex has a room-temperature moment of 4.40 pB falling to 2.23 pB at 83 K and so this complex exhibits 'crossover' behaviour. It is shown that the ligand-field strength of (N-N-N) is less than that of 2,2',2"-terpyridyl since [Fe(terpy),]Br,,H,O is diamagnetic at room temperature. Similar magnetic behaviour has been reported' lo for FeL,X,,nH,O complexes where L is a ring-substituted analogue of 1,lO-phen-anthroline or 2,2'-bipyridyl and X = NCS or NCSe.The magnetic properties of these complexes arise from three effects viz. a phase change leading to a change in susceptibilities over a narrow temperature range a thermal equilibrium between high- and low-spin states and a low-symmetry splitting of the octahedral energy levels leading to moments of intermediate value4 and independent of temperature. A simple thermal equilibrium between the nearly equi-energetic ST, and lAl states accounts for the magnetic behaviour of some iron@) com-plexes of potentially terdentate chelating ligands,' ' ' and the ligand-field strengths of these chelates were found from the spectra of the analogous nickel(1r) complexes to be in the region normally associated with the 'crossover' point.The apparently moderate changes in ligand characteristics required to give spin-paired iron(I1) complexes close to the 'crossover' region are shown1l2 by the preparation of l o ' E. Konig and R. Schnakig to be published. lo' E. Konig and B. Kanellakopulos Chem. Phys. Letters 1972 12 485. Io9 S. E. Livingstone and J. D. Nolan J.C.S. Dalton 1972 218. ' l o A. J. Cunningham J. E. Fergusson H. K. J. Powell E. Sinn and H. Wong J.C.S. ' I 1 H. A. Goodwin and D. W. Mather Austral. J . Chem. 1972 25 715. I l 2 C. M. Harris S. Kokot H. R. H. Patil E. Sinn and H. Wong Austral. J . Chem. 1972, Dalton 1972 2155. 25 1631 The Magnetic Properties of Transition-metal Ions 117 low-spin Fe(bipy) + and high-spin Fe(pq) + complexes where pq is 2-(2'-pyridy1)quinoline.In iron(1rr) complexes the spin crossover occurs with the 6Alg and the ,T2, states and the factors influencing this crossover in iron(rI1) dithiocarbamates have been examined.' The room-temperature moments measured in solution to avoid complicating solid-state interactions were correlated with the pK, values of the secondary amines in a series of complexes of the type Fe(S,CNR,) . The formation of the high-spin state is favoured by a high pK value for HNR, since under these circumstances a carbon-nitrogen double-bond is favoured as in (2). On the other hand when form (2) is sterically disfavoured by a suitable choice of R then form (1) is preferred.These sterically hindered amines give rise to low-spin complexes so that (1) involves a stronger ligand field than (2). How-ever it appears that the steric effect is only secondary since the primary function S /-y /R Fe :C-N \ -7 \ S R (1) S / \ /R Fe C=N \ / \ (2) S R of the substituents R in determining magnetic behaviour is to act as an electron-releasing group. This interpretation contrasts with an earlier one.'I4 The anticipated contraction in the iron-sulphur distances in going from high- to low-spin complexes has been demonstrated' ' by X-ray crystal-structural determin-ations of Fe(CS,N(CH,),) moment = 5.90 pB and Fe(CS,NMePh) mo-ment = 3 . 0 ~ ~ . The thermal equilibrium between the 6A,g and 2T2g states in four tris(monothi0-P-diketonato)iron(m) complexes has been studied' by variable-temperature Mossbauer spectra and susceptibility measurements.In some cases both high- and low-spin forms coexist in varying proportions and give intermediate values for the moments and distinct Mossbauer spectra. A linear relationship between the Mossbauer isomer shifts and the magnetic moments of iron(II1) dithiocarbamates has been claimed to show the increasing importance of back-donation of the d electrons into empty ligand n-orbitals as the low-spin state is approached.' Cobalt(r1) complexes of the type Co(sa1en)B and related molecules where B is an aromatic amine have been prepared'" and their magnetic properties meas-ured in methylene chloride solution at 293-193 K and in the solid state. The room-temperature moments 3.5-1.9 pB and their temperature dependence were interpreted in terms of a thermal equilibrium between the 4A" and 'A' states of the assumed five-co-ordinate square-pyramidal molecules. R. R. Eley R. R. Myers and N. V. Duffy Znorg. Chem. 1972 11 1128. A. H. Ewald R. L. Martin E. Sinn and A. H. White Znorg. Chem. 1969 8 1837. 'I6 M. Cox J. Darken B. W. Fitzsimmons A. W. Smith L. F. Larkworthy and K. A. Rogers J.C.S. Dalton 1972 1192. R. R. Eley N. V. Duffy and D . L. Uhrich J. Inorg. Nuclear Chem. 1972 34 3681. L. G. Marzilli and P. A. Marzilli Znorg. Chem. 1972 11,457. '' P. C. Healy and A. H. White J.C.S. Dalton 1972 1163

ISSN:0069-3022    

DOI:10.1039/GR9726900101

出版商:RSC    

年代:1972

数据来源: RSC

摘要:

5 The Ionization of Carbon Acids By J. R . JONES Department of Chemistry University of Surrey Guildford Surrey This topic is a subject of much interest not only because of the central position occupied by carbon acids in chemistry and the increasing synthetic use being made of carbanions but also because the process of ionization has so many distinguishing features not least being its inherent simplicity. Such a reaction seems therefore to be a good starting point for the study of reaction kinetics in solution. Systematic study would involve not only the determination of acidities but also the effect of different bases and of temperature on the rates of both forward and reverse reactions. This information may be supplemented by the results of isotopic substitution as many unknown or poorly known factors cancel in the ratio of the rates.The following account describes work published during the past twelve months which is relevant to the above considerations. Large numbers of kineticists will always be grateful to Guggenheim' and Swinbourne2 for their methods of analysing kinetic data for first-order reactions where the initial and infinity readings are not available. The disadvantages of both methods have been overcome3 by the development of a non-linear least squares procedure which enables the rate constant for a first-order process to be determined when data are recorded at irregular time intervals and when readings are taken for any length of time (although obviously the longer a reaction can be followed the more accurate the results).1 Rates of Ionization Methods.-With the development of techniques that enable very fast reaction rates to be measured it is now possible to study not only a wider range of reac-tions but also a particular reaction under more diverse conditions. Several modifications or improvements to existing and well-established methods have been reported. Thus to take full advantage of the potential of stopped-flow methods it is highly desirable to automate the sample handling and mixing operations as well as the data acquisition and evaluation steps. This has been done by Beckwith and C r ~ u c h . ~ A stopped-flow instrument in which the initial com-position of the reactant solution can be varied by mixing different volumes of ' E. A. Guggenheim Phil. Mag. 1926,2 538.E. S. Swinbourne J . Chem. SOC. 1960 2371. P. Moore J.C.S. Faraday I 1972,68 1890. P. M. Beckwith and S. R. Crouch Analyt. Chem. 1972,44221. 11 120 J . R. Jones two reactants at any of thirteen volume ratios has been described;' so also has a fully automatic instrument with the ability to prepare and mix samples to acquire kinetic data on the mixed solutions to process the results and to report them in one or more formats.6 In this way the manipulative operations are significantly reduced and extension of the method to more complex chemical reactions is facilitated. A vacuum-type stopped-flow instrument7 suitable for studying reac-tions of highly reactive anionic species has been developed and used to study the reaction between n-butyl-lithium and fluorene in tetrahydrofuran.For those with less money to spend a simple and inexpensive modification of a somewhat dated spectrophotometer is possible making it equally useful for monitoring enzymic reactions and chromatographic separations? Attention has been drawng to a potential source of error in measurements carried out at other than ambient temperatures using a commercially available stopped-flow instrument. The development of a rapid-mixing cell and stopped-flow nuclear magnetic resonance spectrometer has been reported" and the instrument has been used to study the reaction : Ni(NH,)(H,O):+ + H30+ --+ Ni(H,O)g+ + NH; A laser temperature-jump apparatus capable of measuring relaxation times in the 10-8-10-7 s range has been introduced.' ' This makes use of the simulated Raman effect in liquid nitrogen to shift the wavelength of the neodymium-glass laser radiation from 1.06 pm where the absorbance is very small to 1.41 pm, where water absorbs very strongly.A microwave temperature-jump method l 2 suitable for following reactions between neutral reagents in non-conducting solvents has been used to study the rate of formation of the donor-acceptor complex between tetracyanoethylene and hexamethylbenzene. The pressure-jump method13 has been used to study nickel malate complex formation. For investigating much slower reactions two methods one involving the use of selective ion electrode^,'^ and the other using the differential approach l5 seem destined to become more widely used. The high precision of the latter method is ideally suited for studying solvent isotope effectsI6 in media of varying deuterium composition.For measurements of hydrogendeuterium exchange a R. A. Harvey and W. 0. Barcherdt Analyt. Chem. 1972 44 1926. ' D. Sanderson J. A. Bittikofer and H. L. Pardue Analyt. Chem. 1972 44 1934. ' A. G. Evans N. H. Rees and A. Walker J.C.S. Perkin II 1972 1723. H. M. Rasmussen and J . R. Nielsen Analyr. Biochem. 1972 50 648. P. K. Chattopadhyay and J. F. Coetzee Analyt. Chem. 1972,44,2117. l o J . Grimaldi J. Baldo C. McMurray and B. D. Sykes J . Amer. Chem. SOC. 1972 94, 7641. ' I D. H. Turner G. W. Flynn N. Sutin and J. V. Beitz J . Amer. Chem. SOC. 1972 94, 1554. E. F. Caldin J. E. Crooks D. O'Donnell D. Smith and S. Toner J.C.S. Faraday I, 1972 68 849. l 3 S.Harada K. Amidaiji and T. Yasunaga Ber. Bunsengesellschaft phys. Chem. 1972, 76 1752. l 4 G. A. Rechnitz Analyt. Chem. 1972 44 300. l 5 W. J. Albery and A. N. Campbell-Crawford J.C.S. Perkin I I 1972 2190. l 6 W. J. Albery J. R. Bridgeland and J. S. Curran J.C.S. Perkin I I 1972 2203 The Ionization of Carbon Acids 121 facile and direct method” for isotopic analysis of hydrogen or deuterium content of water based on ultrasonic velocity measurements has been reported. The change in sound velocity in going from pure D20 to pure H 2 0 is 97.7 m s- (or some 7 % of the value for pure D20) and varies linearly with concentration. Results.-When carbon acids undergo ionization numerous modes of carbanion stabilization are known to be important. l 8 In the base-catalysed isotope exchange of a series ofpolyfluorinated hydrocarbons (2-hydro-2-phenylhexafluoropropanes) none is more important than the polarizability and induction contributions.l9 Fluorine hyperconjugation seems to be unimportant but a +R carbanion-destabilizing mechanism is important for nearly all substituents and especially fluoro and methoxy. For a series of 2-substituted 1,1,1,3,3,3-hexafluoropropanes, l,l,l-trifluoroethanes and some haloforms in the same solvent (50 50 dimethyl sulphoxide-methanol) with triethylamine as base the two main factors that determine fluorocarbanion and halogenocarbanion stabilities appear to be induction and destabilization by a +R mechanism.20 The effect of adjacent unshared electron pairs on ease of carbanion formation has also been studied.2i The generally accepted mechanism of racemization isotopic hydrogen ex-change and halogenation of carbonyl compounds is rate-determining enoliza-tion followed by fast reaction of the enol or enolate ion.Rappe’s finding22 that bromination of butan-2-one can result in a ratio of monohalides quite different from that predicted on the basis of relative exchange rates under similar con-ditions led to the suggestion that another mechanism involving direct reaction of bromine with unenolized ketone is important. Thorpe and Warkentin23 failed to observe such a term and a product analysis shows that there is no need for different rate-determining steps for alkaline halogenation and deuterium exchange. The relative rates of acetate-catalysed enolization of CH,COCH CH,-COCH,Br and CH,COCHBr are 1 2.2 x lo4 1.5 x lo5 so that the polar effect of the inserted bromine atoms outweighs the opposing steric effect.25 The effect of the two bromines is less than twice as much as one in enhancing the rate, but it can be correlated with the ionization constants of the corresponding a-bromo-acids.26 Tritium exchange from the C-8 position of several purines in nucleosides and in deoxyribonucleic acid27 involves hydroxide ion attack on the 7-protonated form of the purines to give an ylide intermediate which is then reprotonated at ” J.G. Mathieson and B. E. Conway Analyt. Chem. 1972,44 1517. D. J. Cram ‘Fundamentals of Carbanion Chemistry’ Academic Press New York, 1965 Ch. 2. l 9 K. J. Klabunde and D. J. Burton J . Amer.Chem. SOC. 1972,94,820. 2 o K. J. Klabunde and D. J. Burton J . Amer. Chem. SOC. 1972,94 5985. 2 2 C. Rappe Acta Chem. Scand. 1968,22,219; 1967,21 1823. 2 3 J. W. Thorpe and J. Warkentin Canad. J . Chem. 1972 50 3229. 2 4 C. G . Swain and R. P. Dunlap J . Amer. Chem. SOC. 1972,94 5540. 2 5 R. A. Cox and J. Warkentin Canad. J . Chem. 1972,50 3233. 2 6 R. A. Cox and J. Warkentin Canad. J . Chem. 1972,50 3242. 2 7 M. Tomasz J. Olson and C. M. Mercado Biochemistry 1972 11 1235, J . Hine J . Amer. Chem. SOC. 1972 94 6998 122 J. R. Jones C-8 by the medium. For the hydrogen isotope exchange of uridine 5'-phosphate at position 5 cysteine is reported to be a very efficient catalyst.28 The pH-rate profile for the exchange of l-methyl[5-2H]tetrazole in aqueous solution2' has been used as a control experiment to demonstrate that o-complex formation of a heteroaromatic substrate with a transition-metal cation (e.g.Cu2+ Zn2+) can have a major rate-enhancing effect on processes in which substrate ring sub-stituents are eliminated to produce formal sp2 carbanion intermediates. Hydrogen-deuterium exchange of the methyl protons of 1,4,5- and 1,3,5-tri-methyltetrazolium iodides in D20 solution has also been rep~rted,~' as has exchange in several 5-substituted pyrimidine N-~xides.~ Exchange at the 7-methyl group in 6,7,8-trimethyl-l~mazine~~ (l) which serves as a model com-pound for the naturally occurring 8-substituted 6,7-dimethyl-lumazines and for Me flavin nucleotides is both general-acid- and general-base-catalysed (a = 0.46, p = 0.45).of the kinetics of ionization of bromomalon-nitrile (pK = 7.81) shows that this acid behaves like other cyano-substituted carbon acids (p - 0.9-1.0) e.g. malononitrile whereas the behaviour of the much weaker p-nitrobenzyl cyanide (p = 0.61) is considerably different. It is suggested that withp-nitrobenzyl as the activating group several bond changes areassociated with the process of ionization and considerable activation energy is required, whereas with the cyano-group this process contributes negligibly to the activation energy with the result that the potential energy curves are very different. A of the water-catalysed detritiation of malononitrile and its t-butyl derivative in mixed solvents of water with dioxan ethanol and dimethyl sulph-oxide shows the rate to pass thiough a maximum but in the largely non-aqueous solutions the rate is reduced below its value in water.The results are interpreted in terms of medium effects on the activity of the ion-pair transition state and also on the effects these solvents have on the structure of water. A temperature-jump '' Y. Wataya H. Hayatsu and Y. Kawazoe J. Amer. Chem. SOC. 1972,94 8927. 2 9 H. Kohn S. J. Benkovic and R. A. Olofson J. Amer. Chem. SOC. 1972 94 5759. 30 T. Isida S. Fujimori K. Nabika K. Sisido and S. Kozima Ber. Bunsengesellschaft phys. Chem. 1972,76 1246. 3 1 S. A. Krueger and W. W. Pandler J . Org. Chem. 1972,37,4188. 32 R. Stewart and J. M. McAndless J.C.S. Perkin I I 1972 376. 3 3 F. Hibbert and F. A. Long J . Amer. Chem. SOC. 1972,94,2647.3 4 F. Hibbert and F. A. Long J. Amer. Chem. SOC. 1972,94,7637 The Ionization of Carbon Acids 123 Aromatic nitro-compounds react with bases in a variety of ways (see p. 129 for Meisenheimer complex formation). For the reaction between 2,4,6-tri-nitrotoluene and ethoxide ion3’ the rate-determining step is the transfer of a proton from the methyl group to the ethoxide ion. A second species probably a a-complex between TNT and base is also formed. Similarly hydrogen-deuterium exchange in 1,3-dinitrobenzene in sodium metho~ide-methanol~~ occurs by simple proton removal in an internal-return type mechanism ; the radical anion is also formed under these condition^.^' For the ethoxide- and isopropoxide-catalysed deprotonation of di-(4-nitropheny1)methane the activation parameters are nearly the same (10.2,10.4 kcal mol- I) but those for t-butoxide show a lower enthalpy of activation (7.1 kcal mol-I) which is compensated by a much more negative entropy of a c t i ~ a t i o n .~ ~ 2 Acidities of Carbon Acids The pK values of both keto and enol forms of a series of meta- and para-sub-stituted benzoylacetones have been measured by a spectrophotometric method3’ and correlated with the appropriate Hammett substituent constants. The acidities of some 1,1,1-trifluoromethyl-P-diketones in 46 % aqueous acetone have been reported:’ as well as those for a series of meta- and para-substituted 1-arylnitroethanes and arylnitromethanes in water.41 Continuing their extensive studies on the acidities of aromatic hydrocarbons, Streitwieser and co-workers have determined pK values of 19.8 and 18.2 in methanol for 1,3-diphenylindene and fluoradene (2) re~pectively.~~ The high acidity of the latter is usually ascribed to the high resonance stabilization of the anion compared with that of the parent hydrocarbon and relief of strain in (3) 3 5 E.Buncel A. R. Norris K. E. Russell and R. Tucker J. Amer. Chem. SOC. 1972 94, 1646. 36 I. R. Bellobono and G. Sala J.C.S. Perkin 11 1972 169. 3 7 I. R. Bellobono A. Gamba G. Sala and M. Tampieri J. Amer. Chem. SOC. 1972 94, 578 1. 3 8 A. Jacrzewski and K. T. Leffek Canad. J. Chem. 1972,50,24. 39 M. Bergon and J. P. Calmon Bull. SOC. chim. France 1972 1020. 40 K. Bowden G. M. Tanner and D. G. Tuck Canad. J. Chem. 1972,50,2622. 4 1 F. G. Bordwell and W. J.Boyle jun. J. Amer. Chem. SOC. 1972,94 3907. 4 2 A. Streitwieser jun. C. J. Chang and A. T. Young J. Amer. Chem. SOC. 1972 94, 4888 1 24 J . R. Jones changing from sp3 to sp2 hydridization. However the debenzo-analogues of fluoradene 2aH-cyclopent[cd]indene (3) and 9bH-cyclopenta~k]fluorene (4) are not as acidic as the parent compound presumably liecause the strain is not relieved to as great an extent as a n t i ~ i p a t e d . ~ ~ Dibenz[bgJoxocin (5) has been found to be a slightly stronger acid44 (pK - 27) in tetrahydrofuran than xan-thene (pK - 29). Taken in conjunction with the rates of detritiation of penta-fluorobenzene 1,2,3,4-tetrafluorobenzene and o-difluorobenzene the recently measured acidities of these compounds (pK 25.8 31.5 and 35 respectively) allow an estimate of 43 for the pK of benzene.45 Whilst the visible absorption spectra of fluorenylcaesium indenylcaesium and triphenylmethylcaesium in cyclohexylamine or cyclohexylamine-diethylamine change but little with temperature the spectra of fluorenyl-lithium and indenyl-lithium in cyclo hexylaminediethylamine are temperature-dependent and indicate an equilibrium between contact and solvent-separated ion pairs.46 At room temperature the proportion of solvent-separated ion pairs is 95 and 65%, respectively.The small differences between acidities of contact ion pairs and solvent-separated ibIi pairs for several hydrocarbons can be accounted for by a simple electrostatic treatment. The acidities of a number of relatively acidic hydrocarbons (pK - 13-18) have been determined47 in several solvent systems and the small differences that exist interpreted in terms of electrostatic interac-tions between cations and carbanions.These interactions are sensitive to the size of the cations the charge distribution of the carbanions and the polarity of the solvent. The pK values of several 9-alkylfluorenes have been measured4* using both caesium and lithium cyclohexylaniides. 9-Methylfluorene is more acidic than fluorene as is the case in other media; an explanation based on a-bond-strength changes on ionization is favoured. With the development of ion-cyclotron and flowing afterglow techniques, considerable interest is being expressed in gas-phase acidities and the following order has been determined4 at 300 K n-C,H,SH > CH3N02 > CSH6 2 OH i-C3H,0H > C2H,0H > CH30H > C3H4 C,H,CH(CH,) > C6H,-Likewise the basicities of amines which in solution have presented difficulties in CHCl3 > CH3COCH3 > CH3CN > CHZCl, CH3SOCH3 2 C2H2 t-C,H,-CH3 > C3H6 > H2O > C6H6 > H2 > NH3 > C2H4 C6H12 (CH2)3 CH4.J3 B. L. McDowell and H. Rapoport J. Urg. Chem. 1972,37 3261. 44 H. S. Kasmai and H. W. Whitlock jun. J. Org. Chem. 1972 37 2161. 4 5 A. Streitwieser jun. P. J. Scannon and 11. M. Niemeyer J. Amrr. Chc~tri 3To(, 1972, 94 7936. 46 A. Streitwieser jun. C. J. Chang W. B. Hollyhead and J . R. Murdoch. .I. Artwr. Chem. SOC. 1972,944. 5 2 8 8 . 4 7 H. Streitwieser. jun. C . .I. Chiing. and W B. Holljhead J . Amw. Chwz. SOC~. 1972, 94 5292. 4 8 A. Streitwieser jun.C. J . Chang and D. M. E. Reuben J. Amer. Chrnr. Soc. 1972, 94 5730. 49 D. K. Bohme E. Lee-Ruff and L. B. Young J. Amer. Chrm. Soc. 1972 94 5153 The Ionization of Carbon Acids 125 interpretation have been measured in the gas p h a ~ e . ~ O - ~ ~ The basicity order of simple aliphatic amines in aqueous solution (NH < primary < secondary > tertiary) stems from slight differences in the rate of change of the thermodynamic properties in response to progressive alkyl ~ubstitution.~~ The gas-phase basici-ties of the amines increase with increasing methyl substitution and can be inter-preted in terms of effects on the ionization potential of the amine and the hydrogen affinity of the amine radical anion.52 In the gas phase aniline and pyridine are stronger bases than ammonia whereas the reverse is true in aqueous solution.54 3 Aspects of Catalysis The Importance of the Solvent .-The most extensively studied and possibly least understood of solvents water continues to attract interest.Its structure has been further discussed55 and values of K up to 350°C have been rep~rted,'~ as well as in water-methanol mixture^.'^ Methanol appears to be a stronger acid than water over the entire range of solvent compositions the difference becoming larger as the methanol content of the solvent increases. Further com-parison of the relative acidities of water and methanol in the gas phase and in water shows that the hydroxide ions in water are more strongly solvated than methoxide ions.58 The dependence of the acidity and basicity of water on the extent of its hydrogen-bonded structure has been investigated by observing the 'H chemical shifts G(CHC1,) and G(DMS0) in water-solvent-R,NBr mixtures.The available evidence points strongly to enhanced water basicity as a con-sequence of enhanced water structure but the effect if any on water acidity is not clear.59 A calorimetric study of the enthalpies of reaction between water and dimethyl sulphoxide in dilute dioxan solution fails to confirm the existence of a 2H20,DMS0 adduct.60 The free energies of transfer of ionic solutes from H,O to D20 are usually small and despite their importance in the interpretation of kinetic salt effects and the study of aqueous electrolyte solutions relatively few values are available. Lowe and Smith61 report the first use of a cation-sensitive glass electrode for this purpose ; subsequently lanthanum fluoride single-crystal and sodium-responsive glass electrodes were used to obtain the free energies of transfer of 5" M.Taagepera W. G. Henderson R. T. C. Brownlee J. L. Beauchamp D. Holtz and R. W. Taft J . Amer. Chem. SOC. 1972 94 1369. 5 1 E. M. Arnett F. M. Jones M. Taagepera W. G. Henderson J. L. Beauchamp D. Holtz, and R. W. Taft J. Amer. Chem. Soc. 1972 94 4724. 5 2 D. H. Aue H. M. Webb and M. T. Bowers J. Amer. Chem. SOC. 1972,94,4728. 5 3 W. G. Henderson M. Taagepera D. Holtz R. T. McIver jun. J. L. Beauchamp and R. W. Taft J. Amer. Chem. Soc. 1972 94 4728. 5 4 J. P. Briggs R. Yamdagni and P. Kebarle J. Amer. Chem. Sac. 1972 94 5128. 5 5 A. T. Hagler H.A. Scheraga and G. Nemethy J. Phys. Chem. 1972 76 3229. 56 J. R. Fisher and H. L. Barnes J. Phys. Chem. 1972 76,90. 5 7 C. H. Rochester J.C.S. Dalton 1972 5 . 5 8 G. H. Parsons and C. H. Rochester J.C.S. Faraday I 1972 68 523. 5 9 J. E. Gordon J. Amer. Chem. Soc. 1972 94 650. 6 o F. Rallo and F. Rodante Ann. Chim. (Irafy) 1972 62 221. 6 1 B. M. Lowe and D. G. Smith J.C.S. Chem. Comm. 1972,989 126 J. R. Jones sodium fluoride from H 2 0 to H202-H20 mixtures.62 The free energy of transfer of various solutes in H,O-D20 mixtures as determined from solubility measure-ments varies linearly with the deuterium concentration of the solvent.63 In evaluating single-ion solvent activity coefficients O r > + and for transfer of cations A' or of anions B- from a reference solvent (superscript 0) to another solvent (superscript s) experience shows that different groups of extra-thermodynamic assumptions give much the same values as for example in the transfer of silver cation from acetonitrile to 14 other solvents at 25 "C.Parker and c o - ~ o r k e r s ~ ~ strongly recommend that the simplest of these namely the assumption of negligible liquid-junction potential between Ag I AgClO (0.01 moll- l ) half-cells in different solvents when linked by a salt bridge of tetra-ethylammonium picrate (0.01 moll- ') be adopted as the standard procedure. hem me^^^ has speculated on the possibility of there being strong cation-cation interactions in water the lifetime of these cation pairs being comparable with that of the more usual ion-pairs.In solvents of lower polarity salts contain-ing a carbanion e.g. fluorensylsodium or a radical anion e.g. coronenesodium, can exist as contact or solvent-separated ion pairs. In the proton-transfer reaction between triphenylmethane and polystyryl anion in ethereal solvents the free ions are much more reactive than the ion pairs.66 Advantage may be taken of the fact that macrocyclic polyethers are able to form complexes with alkali-metal salts. In this way the solubilities of the salts may be increased as well as the dissociation of the ion pairs leading to the formation of highly reactive unsolvated anions ; in a more subtle way contact ion-pairs may be converted into solvent-separated ion-pairs. This interesting work has been reviewed both by P e d e r ~ e n ~ ~ and Smid.68 N.m.r.studies of the influence of the solvent on ion association have also been reported.69 Linear Free-energy Relationships.-The Hammond postulate 70 that extremely exothermic reactions with small activation energies will have transition states that closely resemble the reactants whereas the transition states of strongly endothermic reactions with large activation energies will bear a close relationship to the products has been put on a more quantitative basis.71 The derived equa-tions are identical with those originally developed by Marcus72 for electron-transfer reactions and the results show that the Bronsted exponent is not always a reliable guide for predicting the position of the transition state along the reac-6 2 A. K. Covington K.E. Newman and M. Wood J.C.S. Chem. Comm. 1972 1234. 6 3 H. Selander and J. L. G. Nilsson Acta Chem. Scand. 1972 26 2433. 6 4 R. Alexander A. J. Parker J. H. Sharp and W. E. Waghorne J. Amer. Chem. SOC., 6 5 P. Hemmes J . Amer. Chem. SOC. 1972 94 75. 6 6 L. L. Chan and J. Smid J. Phys. Chem. 1972,76 695. 6 7 C. J. Pedersen and H. F. Krensdorff Angew. Chem. Internat. Edn. 1972 11 16. 6 8 J. Smid Angew. Chem. Internat. Edn. 1972 11 112. 6 9 Y . Y . Lim and R. S. Drago J. Amer. Chem. SOC. 1972,94 84. ' O G. S. Hammond J. Amer. Chem. SOC. 1955 77 334. 7 1 J. R. Murdoch J. Amer. Chem. SOC. 1972,94,4410. 7 2 R. A. Marcus J. Phys. Chem. 1968,72 891. 1972 94 1148 The Ionization of Carbon Acids 127 tion co-ordinate a point forcefully made by Bordwell and Boyle4’ in their studies on aliphatic nitro-compounds.The non-linear Bronsted plots observed for general acid-base catalysis of several acyl aminolysis reactions with nitrogen or oxygen leaving-groups have been interpreted as evidence of a change in mechanism.73 The deviation of the point for HF in the acid-catalysed hydrolysis of vinyl ethers is due to the fact that all of the negative charge remains localized on the fluorine atom whereas part of the charge formed on proton removal from carboxylic acids is dispersed on to the more distant oxygen.74 A semi-empirical approach to the problem of calculating the potential energy surface and hence of predicting the configuration and energies of transition states has been developed.75 The model is tested by comparing predicted and observed structure-reactivity relations ; for carbonyl hydration reactions it is suggested that nucleophilic attack occurs synchronously with a single proton transfer.Jencks7 has examined various aspects of complex general acid-base-catalysed reactions in which one or more proton transfers accompany another more difficult process using the three-dimensional reaction co-ordinate contour diagrams used by More O’Ferral17 for studying carbon elimination reactions. It is suggested that such reactions can only occur in aqueous solution (a) when the change in pK converts an unfavourable proton transfer into a favourable one and (b) at sites that undergo a large change in pK during the course of the reaction. The driving force of the reaction is the free energy of the proton-transfer process itself rather than stabilization of the transition state by hydrogen-bonding to the The Bronsted p exponent gives a positive correlation with the magnitude of the a effect so that a study of proton transfer from t-butylmalononitrile (p - 0.9) is a good choice for investigating its importance in the ionization of carbon acids.Detritiation studies in a-effective (methoxylamine hydrazine) and non-a-effective buffers however lead to no significant deviations from the Bronsted r e l a t i ~ n s h i p . ~ ~ The past year has witnessed an increasing number of studies in highly basic media and correlations with the appropriate acidity functions. The simple but nevertheless very important reaction between molecular hydrogen (or deuterium) and hydroxide ion in aqueous solution leading to ortho-para conversion (or isotopic exchange) has been studied” in dimethyl sulphoxide-water mixtures.The rates of exchange increase by a factor of lo4 as the medium composition is changed from 0 to 99.5 % dimethyl sulphoxide the plot of log k versus H - having 7 3 J. P. Fox M. I. Page A. Satterthwait and W. P. Jencks J . Amer. Chem. SOC. 1972, 7 4 A. J. Kresge and Y. Chiang J . Amer. Chem. SOC. 1972,94,2815. ” J. E. Critchlow J.C.S. Furuduy I 1972 68 1774. ” W. P. Jencks Chem. Rev. 1972 72 705. ” R. A. More O’Ferrall J . Chem. SOC. (B) 1970 274. 7 8 W. P. Jencks J . Amer. Chem. SOC. 1972 94 4731. 7 9 R. F. Pratt and T. C. Bruice J . Org. Chem. 1972 37 3563. *’ E. A. Symons and E. Buncel J . Amer. Chem. SOC. 1972,94 3641.94 4729 128 J. R. Jones an initial slope of 0.23 which increases to 0.36 in the more basic solutions. The corresponding plot (although over a much narrower H - range) for the detritiation of chloroform" has a slope of unity compared with 0.7 for 1,6dicyanobutene. This result explains why general-base catalysis was only observed for the latter and is consistent with the primary isotope effects observed (kJkD)OH- = 3.5 for the cyanocarbon and 1.4 for chloroform. Bowden and Cookg2 have correlated the rates of hydroxide-catalysed iso-merization of a series of 3- and 4-substituted allylbenzenes as well as 1,3,3-triphenylprop-1-yne in aqueous dimethyl sulphoxide solutions with the H -values. The results of substituent effects kinetic hydrogen isotope effects and the slopes of the log k versus H - plots are all consistent with the proposed mechan-ism involving rate-determining proton abstraction.Several reactions in concen-trated sodium methoxide-methanol solutions however provide no example of a direct correlation between reaction rate and either the H - function orstoicheio-metric base con~entration.~~ In fact the best relationship is between log k and H - - pKMeoH - log (CMeO-/CMeOH) the slopes being related to the transition-state structure for the particular reaction. Large increases in the rates of hydrolysis and methanolysis of cyclic sulphate and sulphonate esters in highly basic media have been reported.84 Such findings have usually been ascribed to either the desolvation of the hydroxide ion or to the superior ability of the dipolar aprotic solvent to solvate the transition state.As the rate enhancements are generally accompanied by large decreases in the enthalpy of activation in the dipolar aprotic solvent relative to the polar protic solvent the two explanations can be subjected to an experimental test.85 The difference in the enthalpies of the reactants in the two kinds of solvents (6 AH;) can be determined calorimetrically and if the first explanation is correct this should then be equal to the difference in the enthalpies of activation (AH*) in the two solvents. In a particular example it turns out that the enthalpy of transfer of the reactants from the dipolar solvent to the protic solvent is three times as great as the differences in the AH* values in the two kinds of solvent.The H - values for sodium glycoxide-thylene glycol solutions using t-butyl-phenols as indicators are lower than when nitroanilines and diphenylamines are used,86 and an attempt has been made to explain the different activity-coefficient behaviour of the indicators. The effect of adding some protic and dipolar aprotic solvents to this system is to increase the H - values the order of effectiveness being DMSO > Me,CHO > Bu'OH > Me,CO > MeCN > MeOH.87 An H-scale for methanolic sodium methoxide solutions (up to 3 moll- ') has been con-structed from the ionization of 1,3-di~henylindene~~ and a J acidity function '' Z . Margolin and F. A. Long J . Amer. Chem. SOC. 1972 94 5108. 8 2 83 84 J . H. Smith T. Inone and E. T. Kaiser J .Amer. Chem. SOC. 1972,94 3098. 8 5 P. Haberfield J. Friedman and M. F. Pinkston J . Amer. Chem. SOC. 1972 94 71. 8 6 L. Aiyar A. N. Datta and K. K. Kundu J . C . S . Perkin ZZ 1972 1046. '' K. K. Kundu and L. Aiyar J . C . S . Perkin ZI 1972 715. K. Bowden and R. S. Cook J . C . S . Perkin / I 1972 1407. R. A. More O'Ferrall J . C . S . Perkin IZ 1972 976 The Ionization of Carbon Acids 129 for methanol4imethyl sulphoxide mixtures containing NaOMe (0.1 moll- ) in respect of methoxide addition to substituted anisoles.88 Meisenheimer Complex Formation.-In the reaction of aromatic nitro-compounds with bases proton abstraction is the least well-characterized process. The formation of covalently bonded adducts (Meisenheimer or o-complexes) is far more common and several papers bearing on both the kinetic and equilibrium aspects have been published.The stopped-flow method has been used to study the interaction of 4-methoxy-3,5-dinitr~pyridine'~ and 2-chloro-4,6-dinitro-anisole" with methoxide ions in methanol-dimethyl sulphoxide solutions. The equilibrium constant between 1,3,5-trinitrobenzene and hydroxide ions has been studied as a function of medium composition for the dimethylformamide-water system and found to vary from 3 1 mol- ' in purely aqueous solution to greater than lo5 1 mol- in 50 mol % dimethylformamide mainly because of the increasing desolvation of the hydroxide ion.' ' Equilibrium constants between several substituted anisoles and methoxide ion have also been determined,92 and in the case of 3,5-dinitropyridineg3 the Meisenheimer complex is more stable than that formed between trinitrobenzene and methoxide ion.Further aspects of the stabilities of these complexes have also been discussed9L96 and in one case97 the heat of formation has been determined. The first case of Meisenheimer complex formation involving an aromatic rather than an aliphatic amine has also been rep~rted.'~ Miscellaneous.-In the hydration of chloral in methan01:~ the order with respect to the solvent is three similar to that previously estimated for addition of water to various carbonyl compounds. Thermodynamic and activation parameters have been reported loo for the reversible hydration of 1,3-dichloroacetone in dioxan and in the corresponding reaction of a series of ring-substituted tri-fluoroacetophenones in dimethyl sulphoxide-water and sulpholane-water mix-tures"' the latter have a dehydrating effect relative to water.In mixtures of water and dimethyl sulphoxide down to 15 mol % water they are more hydrating with respect to the carbonyl group than is pure water. The rate of the uncatalysed hydration of 4-methoxytrifluoroacetophenone in aqueous sulpholane drops drastically as the water content of the medium decreases. 8 8 M. R. Crampton M. A. E. Ghariani and H . A. Khan J.C.S. Perkin ZZ 1972 1178. 8 9 F. Terrier A. P. Chatrousse and R. Schaal J . Org. Chem. 1972 37 3010. 90 F. Terrier F. Millot and R. Schaal J.C.S. Perkin ZZ 1972 1192. 9 L E. A. Symons and E. Buncel Canad. J . Chem. 1972,50 1729. 9 2 M. R. Crampton and H. A. Khan J.C.S. Perkin ZZ 1972 1173.9 3 A. P. Chatrousse and F. Terrier Bull. SOC. chim. France 1972 4549. 9 4 M. P. Simonin M. L. Lecourt F. Terrier and C. A. Dearing Canad. J . Chem. 1972, 9 5 9 6 M. R. Crampton and H. A. Khan J.C.S. Perkin ZZ 1972 2286. 9 7 J. W. Larsen K. Amin S. Ewing and L. L. Magid J . Org. Chem. 1972,37 3857. 99 R. P. Bell and D. G. Horne J.C.S. Perkin IZ 1972 1371. l o o R. P. Bell and P. E. Sorensen J.C.S. Perkin 11 1972 1740. l o ' R. Stewart and J. D. Van Dyke Canad. J . Chern. 1972,50 1992. 50 3558. M. R. Crampton and H. A. Khan J.C.S. Perkin ZZ 1972 733. E. Buncel and J. G. K. Webb Canad. J . Chem. 1972,50 129 130 J . R. Jones When the iodination of o-carboxyacetophenone is carried out in self-buffered solutions the rate can be attributed solely to intramolecular proton transfer from the acetyl group to the carboxylate group.'02 In the mutarotation of 2,3,4,6-tetramethyl a-D-glucose in benzene and cyclohexane micellar catalysis leads to a considerable rate enhan~ernent,"~ as has been found in other ' 0 5 4 Kinetic Isotope Effects The theoretical interpretation of isotope effects in such diverse fields as vibrational spectroscopy gas-phase equilibrium constants and reaction kinetics has been reviewed.'06 An increasing use is being made of models in calculating isotope effects e.g. in SN2 displacement reactions :lo' Y + REH,X -+ Ty . ? a REH .? XI' -+ R?H,Y + X, The carbon isotope effect goes through a maximum as a function of n the bond order of the Y - . . C bond supporting the qualitative suggestion made previously by Fry'08 that a reaction of this type can be viewed as an 'RCH,' group transfer from X to Y with mechanistic implications similar to those of hydrogen-transfer reactions.The chlorine isotope effect on the other hand increases continuously as one goes from a reactant-like to a product-like transition state. Model calculations log indicate that for reactions exhibiting reasonable primary hydrogen isotope effects the effective lower limit to the pre-exponential ratio A d A is -0.7-0.5 thereby lending support to the common procedure of inter-preting experimental values lower than this to the operation of tunnelling effects. Calculations of primary hydrogen isotope effects in the racemization of 2-methyl-3-phenylpropionitrile show that very low values may be obtained for highly unsymmetrical transition states in line with the experimental results and the product-like transition state.' lo The kinetic hydrogen isotope effect for the hydroxide-catalysed ionization of (d)-phenylmethylacetophenone has been studied' ' ' as a function of changing medium basicity by increasing the proportion of dimethyl sulphoxide in the solvent; kJkT passes through a clearly defined maximum at an H - of 16.5, corresponding to ApK = 0.The Bronsted exponent /? is 0.49 for both isotopes and the activation energy difference E - E reaches a maximum value at an * l o ' R. P. Bell B. G. Cox and J. B. Henshall J.C.S. Perkin IZ 1972 1232. J. H. Fendler E. J. Fendler R. T. Medary and V. A. Woods J. Amer. Chem. SOC., 1972,94 7288. J.H. Fendler and R. R. Liechti J.C.S. Perkin IZ 1972 1041. C. A. Bunton and S. K. Huang J. Org. Chem. 1972,37 1790. I o 6 M. Wolfsberg Accounts Chem. Res. 1972 5 225. l o ' L. B. Sims A. Fry L. T. Netherton J. C. Wilson K. D. Reppond and S. W. Crook, J. Amer. Chem. SOC. 1972,94 1364. ''* A. Fry Pure. Appl. Chem. 1964 8 409. M. E. Schneider and M. J. Stern J . Amer. Chem. SOC. 1972 94 1517. ' l o N A. Bergman W. H. Saunders jun. and L. Melander Actu Chem. Scund. 1972, 26 1130. "' D. W. Earls J. R. Jones and T. G. Rumney J.C.S. Furuduy I 1972 68 925 The Ionization of Carbon Acids 131 H - of 16.8. The pre-exponential ratios AH/AT reflect the importance of solvent-reorganization contributions. A quantitative model ' I 2 that was developed in order to investigate the importance of such factors in proton-transfer processes predicts that reactions in which the activated complex has a non-equilibrated environment should be rare and that when they do occur the deviation of solvent configuration from its equilibrium state is expected to be toward that configuration which is appropriate for an internal structure in which the proton is half transferred.Although tunnelling seems to be unimportant in the hydroxide-catalysed ionization of both 2,4-dimethylpentan-3-one and 3,5-dimethylheptan-4one,' l3 the rate of hydrogen-atom abstraction from solid acetonitrile at 77-47 K pro-ceeds almost totally via quantum-mechanical tunnelling.' l4 From a mass spectral study of the dedeuteriation of [2H6]acetone it is claimed'15 that the primary hydrogen isotope effect is considerably lower than a previously determined value.Isotope effects have been measured in the pyrolysis of esters,l16 in the acid-catalysed exchange of several indoles ' '* ' and in the protonation of olefinic substrates.' Schowen'20 has considered at length the mechanistic deductions that may be made from a study of solvent isotope effects. Similarly Albery and Davies12' have discussed what mechanistic conclusions may be drawn from the curvature of solvent isotope effects as obtained from studies in H20-D20 mixtures. Their findings should facilitate the interpretation of the curvature and may be parti-cularly useful in distinguishing single parallel and consecutive transition states. The observed hydroxide ion isotope effect kgho/kD,&o = 0.72 for the detritia-tion of 1,4-dicyanobut-2-ene1 22 has been separated into a secondary kinetic isotope effect kEfP_/kg&o = 0.57 and a secondary solvent isotope effect kg&o/ gho = 1.27.The effect of changing the solvent from H 2 0 to D20 on the rates of ionization of 2-nitropropane as well as the change in K have been quanti-tatively explained'23 on the basis of the formula OH;(H,OH,) for the aqueous hydroxide ion in which b and c denote non-equivalent positions and where it is assumed that different fractionation factors apply to the three hydrogen sites (4a z 1.2-1.5 +, N 0.654.7 4c z 1). ' l 2 J. L. Kurz and L. C. Kurz J . Amer. Chem. SOC. 1972 94 4451. l ' ' R. A. Lynch S. P. Vincent Y . T. Lin L. D. Smucker and S. C. Subba Rao J. Amer.Chem. SOC. 1972,94,8351. R. J. Le Roy E. D. Sprague and F. Williams J. Phys. Chem. 1972 76 546. 'I5 J. Hine J. C. Kaufmann and M. S. Cholod J . Amer. Chem. SOC. 1972,94,4590. R. Taylor J. C.S. Perkin ZI 1972 165. B. C. Challis and E. M. Millar J.C.S. Perkin IZ 1972 11 16. B. C. Challis and E. M. Millar J.C.S. Perkin 11 1972 1618. Phys. Chem. 1972,76,295 1. * ' W. J. Albery and M. H. Davies J.C.S. Furuduy I 1972 68 167. E. A. Walters and F. A. Long J . Phys. Chem. 1972,76 362. V. Gold and S. Grist J.C.S. Perkin 11 1972 89. ' I 9 M. M. Kreevoy R. Eliason R. A. Landholm T. S. Straub and J. L. Melquist J. ' 2 o R. L. Schowen. Progr. Phys. Org. Chem. 1972 9 275 132 J. R. Jones 5 Labelled Carbon Acids With the increasing use being made of labelled compounds any improvements in existing methods of preparation or the discovery of new ones are to be greatly welcomed.It is frequently the case that conventional homogeneous and hetero-geneous catalysts require elevated temperatures and reaction times of hours before equilibrium is reached. However it has been reported'24 that a new range of highly active catalysts - metal halides of the type MoCl WCl AlCl,, and SbCl - readily catalyse the exchange between two aromatic molecules such as C,D and toluene. The reaction is characterized by the apparent absence of steric effects and complicating side-reactions. The discovery that organo-aluminium dihalides such as ethylaluminium dichloride catalyse very rapid exchange of hydrogen atoms between aromatic nuclei is an attractive alternative method of deuteriation. 2 5 The same organoaluminium dihalide catalysts with tritiated water as the isotope source and catalyst promoter may be used for instantaneous tritium labelling.' 26 12' J. L. Garnett M. A. Long R. F. W. Vining and T. Mole J.C.S. Chem. Cornm. 1972, 1172. J. L. Garnett M. A. Long R. F. W. Vining and T. Mole J . Amer. Chem. Sac. 1972, 94 5913. M. A. Long J. L. Garnett R. F. W. Vining and T. Mole J . Amer. Chem. SOC. 1972, 94 8632

ISSN:0069-3022    

DOI:10.1039/GR9726900119

出版商:RSC    

年代:1972

数据来源: RSC

摘要:

6 Kinetics and Mechanism of Addition Po I ymer iza t io n By P. HYDE and A. LEDWITH Donnan laboratories University of Liverpool Liverpool 169 3BX 1 Free-radical Polymerization Of particular interest in free-radical polymerization is the direct evaluation of the rate constant for chain propagation (k,). Bresler and co-workers' have developed an e.s.r. technique which permits quantitative measurement of the stationary concentrations of growing chains. For styrene polymerization at 25 "C they give k = 66.5 1 mol-' s- ' and E = 9.0 kcal mol- ' values which are within the (wide) range determined earlier by various workers. The pre-exponen-tial factor (A,) may be determined from the equation ekT h A = - exp (AS*/R) AS* values have been estimated using a method of group contributions2 and give values reliable to 1-1.5 kcal mol-' for vinyl acetate (VA) styrene (STY), methyl acrylate (MA) and methyl methacrylate (MMA) polymerization.Sub-sequent calculations of A are generally within a factor three of values determined experimentally. A comprehensive study of the polymerization of vinyl acetate both in bulk and in glacial acetic acid has been made and the effect of temperature on k,/(k,)f and transfer constants eval~ated.~ Although reasonable rates of polymerization can be achieved in glacial acetic acid under the conditions used polymer molecular weights were lower than in the bulk system. Studies of branching in vinyl acetate polymers have established that transfer to polymer backbone at 60°C is 2.4 times more frequent than it is to the pendant acetoxy-group and 4.8 times more frequent at 0 "C.Data on transfer to monomer show that this occurs exclusively uia the acetoxy-gro~p.~-' ' S. E. Breslcr F. N . ' K i ~ b e k ~ ~ . V. N . Fomichev. andV. N . Shadrin Makrornol. Chem., 1972 157 167. ' M. Guaita Makromol. Chem. 1972 154 191. S. P. Potnis and A. M. Deshpande Makromol. Chem. 1972 153 139. ' S. Nozakura Y. Morishirna and S. Murahashi. J . Polymer Sci. Part A - I Polymer Chem. 1972.10 2767. ' S. Nozakura Y. Morishima and S. Murahashi J . Polymer Sci. Part A-I Polymer Chem. 1972 10 2781. S. Nozakura Y . Morishima and S. Murahashi J . Polymer Sci. Part A-I Polymer Chern. 1972 10,2853. S . Nozakura Y . Morishima and S. Murahashi J . Polymer. Sci. Part A - I Polymer Chem. 1972,10,2867.13 134 P. Hyde and A . Ledwith It is a long-held assumption in free-radical kinetics that reaction rates are in general little affected by the medium. An investigation of the AIBN-initiated polymerization of MMA at 60 "C in a variety of solvents shows that (i) Ri varies little over the range of solvents employed (q = 2.54-27.88 mP) (ii) k decreases markedly with increased viscosity and (iii) k reaches a maximum in diethyl malonate solution (q = 6.61 mP). (i) and (ii) are not surprising and the change in k seems to be a solvent effect rather than a viscosity effect but no explanation is offered.8 Solvent and temperature effects have been investigated for MMA polymerization.' Both solvent and temperature as well as initial monomer concentration affect the stereochemistry of the resulting polymers.The effect of bromotrichloromethane on the polymerization of MMA has been studied by radiotracer and g.p.c. methods." Transfer constants for the first seven radical intermediates increase up to the fourth by which time the value is equal to that for a normal macroradical. The polymerization of MMA in the presence of isotactic poly(MMA)" and finely divided silica12 has been studied. Of interest is the polymerization of n-butyl methacrylate on the surface of the synthetic zeolite Faujasite,' initiated by adsorbed benzoyl peroxide. Polymerization of several acrylates and methacrylates in dimethylformamide has been de~cribed.'~ Differences in reactivity are discussed in terms of the nature of the substituent 01 to the double bond.The preparation and polymer-ization of highly chlorinated ethyl acrylates and methacrylates has been reported.' These may find use as cross-linking agents for polymers containing t-amine groups. Telechelic polymers (polymers with reactive end-groups for use as pre-poly-mers) are increasing in importance. Free-radical telechelic polymers may be prepared by using appropriately substituted initiators. The polymerizations of butadiene with 4,4-azobis-(4-cyano-n-pentanol) and 4,4'-azobis-(4-~yanovaleric acid)' and of isoprene with di-(4-hydroxybutyl)-2,2'-azobis-isobutyrate'' have been described and give pre-polymers with highiy reproducible properties. Because of their possible use in the drug industry polymers which contain heterocyclic nuclei are receiving more attention.Emphasis at the moment is on the synthesis of large numbers of new monomers and evaluation of their polymer-ization and copolymerization characteristics. Studies on vinylated oxazoles (l), thiazoles (2) isoxazoles (3) and oxadiazoles (4)18 have been performed. The M. M. Zafar Makromol. Chem. 1972 157 219. P. Goldi and H.-G. Elias Makromol. Chem. 1972,153 81. R. Buter Y. Y. Tan and G. Challa J . Polymer Sci. Part A - I Polymer Chem. 1972, 10 1031. J. Rychly and M. LazAr European Polymer J. 1972 8. 7 1 1. H. Hrabhk and H. PivcovA ( a ) Coll. Czech. Chem. Comm. 1972,37,3279; (b) J . Polymer Sci. Part A-1 Polymer Chem. 1972 10 3 125. l o C. A. Barson A. R. Luxton and J. C. Robb J.C.S. Faraday f 1972,68 1666. " l 2 T. R. Manley and B. Murray European Polymer J.1972 8 1145. l 4 J. Safko and E. Turksa Makromol. Chem. 1972 156 297. l 6 S. F. Reed jun. J . Polymer Sci. Part A - I Polymer Chem. 1972 10 649. l 7 S. F. Reed jun. J . Polymer Sci. Part A- I Polymer Chem. 1972 10 2493. Y. Iwakura F. Toda H. Suzuki N. Kusakawa and K. Yagi J . Polymer Sci. Part A - I , Polymer Chem. 1972 10 1133 Kinetics and Mechanism of Addition Polymerization 135 C=CH, C=CH2 synthesis of various monomers containing the N-phenothiazinyl group (5) is of interest because of the electron-donating properties and redox susceptibility of this group. Of the various monomers prepared (substituted acrylates meth-acrylates and acrylamides) all were susceptible to free-radical polymerization. P-(N-Phenothiaziny1)thyl vinyl ether (5 ; R = -CH,-CH,-0-CH=CH2) was also prepared and found to be polymerizable by cationic initiators.I R Methods have been described for the preparation of a range ofpoly(acry1amides) and poly(methacrylamides)20 and of polymers containing cholesteryl groups either adjacent to the main chain21 or separated from it by a chain of eight or more atoms2, Thermal initiation of vinyl polymerization is generally accomplished using either peroxides or azo-compounds. The use of a series of acra'a'-tetra-substituted bibenzyls (6) has been de~cribed.,~ As with similar systems these employ higher temperatures (60-1 10 "C) than the common initiators owing to the greater strength of the central carbon-carbon bond. Ester derivatives of act'-dicyano-bibenzyls (6; R' = CN R2 = C0,Alk) were found to be good initiators (f x 0.3-0.6) whereas corresponding phenyl derivatives (6 ; R' = CN R2 = Ph) were inefficient.l 9 H. Kamogawa J . Polymer Sci. Part A-1 Polymer Chem. 1972 10 95. 'O P. Ferruti A. Bettelli and A. Ferk Polymer 1972 13 462. Y. Tanaka S. Kabaya Y . Shimura A. Okada Y. Kurihara and Y . Sakakibara, J . Polymer Sci. Part B Polymer Letters 1972 10 261. 2 2 H. Kamogawa J . Polymer Sci. Part B Polymer Letters 1972 10 7. 23 H. A. P. de Jongh C. R. H. I. de Jongh W. G . B. Huysmans H. J. M. Sinnige W. J. De Klein W. J. Mijs and H. Jaspers Makromol. Chem. 1972 157 279 136 P . Hyde and A . Ledwith In contrast to earlier work claiming that difuroyl peroxide was inefficient in initiation of vinyl polymerization M01nar~~ has estimated that it is comparable to dibenzoyl peroxide in efficiency ofinitiation of styrene polymerization (f x 0.9), and to dilauroyl peroxide in the polymerization of vinyl acetate ( f x 0.7).Kinetic analysis indicates that chain transfer to difuroyl peroxide is important. Interaction of dibenzoyl peroxide (BPO) with amines to produce initiating species is well known. Applications of this reaction to the curing of epoxy-resins25 and the preparation of a polymeric emulsifier capable of initiating polymerization,2 have been made. A charge-transfer interaction of BPO with N-vinylcarbazole (NVC) is suggested as being the reason for anomalous kinetics in the BPO-initiated polymerization of NVC.” Whereas AIBN gives conven-tional kinetics of the form R = K[M] BPO-initiated systems have R = K[MI2[I].Species (7) is assumed to be the active initiator. Because of their lack of susceptibility to induced decomposition reactions, azo-compounds are the most convenient to use at the high initiator concentrations employed for studies of primary radical termination. 2,2’-Azobis-(2,4-dimethyl-valeronitrile) has been used in STY28u and VAZ8’ polymerizations. In the latter case determinations of the initiator efficiency (f = 0.5) and the primary radical termination rate constant (1.4 x lo9 1 mol-’s-’) were made. 4,4-Azobis-(4cyanopentanoic acid) is a water-soluble initiator used in the polymerization of a~rylamide.~’ Data indicate an initiator efficiency of 0.65 at 25°C. At low monomer concentrations R is proportional to explained in terms of 2 4 S. Molnar J .Polymer Sci. Part A - I Polymer Chem. 1972 10 2245. 2 s S. S. Labana Y. F. Chang J . Polymer Sci. Part A - I Polymer Chem. 1972 10 1861. 2 6 S. N. Trubitsyna Kh. K. Ruzmetova and M. A. Askarov Polymer Sci. (U.S.S.R.), 1971 13 1950. 2 7 R. G. Jones E. Catterall R. T. Bilson and R. G. Booth J.C.S. Chem. Comm. 1972,22. 2 8 K. Ito ( a ) J . Polymer Sci. Part A - I Polymer Chem. 1972 10 931; ( b ) ibid. p. 1491. 2 9 M. Baer J. A. Caskey and A. L. Fricke Makromol. Chem. 1972 158 27 Kinetics and Mechanism of Addition Polymerization 137 cage effects. The polymerizations of MMA initiated by 9-diazafl~orene~~ and 4,4'-diazidoa~obenzene~ have also been investigated. AIBN decomposition has been shown to be accelerated in the presence of bis-( - )-ephedrine-copper(I1) chelate ;3 the mechanism of this unusual behaviour is by no means clear but is suggested as involving reductive decyanation of the AIBN when co-ordinated to the chelate.Substituted tetrazenes (8) have been shown to be efficient initiators of vinyl polymerization either alone,33 in the presence of CCl and water,34 or in the presence of nucleic acid bases.35 R2 R3 \ / N-NyN-N / \ R' R4 Initiation of vinyl polymerization has been shown (Scheme 1) to be feasible with the systems dimethylaniline N-oxide-tosyl chloride [via radicals (9) and ( lO)I3 or organic acids-tetraphenylborate salt (uia phenyl radi~al).~ Me I I Me Ph-N-0 + Ts'C1- -+ Me I Me 1 Me I 'CH, (10) (9) monomer I -H+ I monomer Polymer - Ph-N +- Ph-Nf + -0Ts + Polymer Ts =Me Scheme 1 3 0 T.Nakaya M. Tanaka and M. Imoto Makromol. Chem. 1972 155 169. 3 1 T. Doiuchi T. Nakaya and M. Imoto Makromol. Chem. 1972 161 231. 3 2 V. Horanska J. Bartofi and Z. Mafiasek J . Polymer Sci. Part A-I Polymer Chem., 1972 10 2701. 3 3 K. Sugiyama T. Nakaya and M. Imoto Makromol Chem. 1972 161 219. 3 4 K. Sugiyama H. Watanabe T. Nakaya and M. Imoto Makromol. Chem. 1972 162, 3 5 K. Sugiyama T. Nakaya and M. Imoto Makromol. Chem. 1972 161 207. 36 T. Sato M. Yoshioka and T. Otsu Makromol. Chem. 1972 153 47. 3 7 T. Sato E. Kashino N. Fukumura and T. Otsu Makromol Chem. 1972,162 9. 291 138 P. Hyde and A . Ledwith Photo-initiation is of great importance since polymerizations can then be carried out at much lower temperatures than generally necessary for thermal initiation.The use of aromatic carbonyl compounds is well known and has recently been reviewed.38 Normal sensitization uses wavelengths up to approx-imately 40Onm but it has been shown that combinations of various dyes and ascorbic acid are effective up to 54611m.~~ Amines are reported to have an accelerating effect on the photopolymerization of MMA.,' This is thought to be due to the formation of a complex between excited monomer (M) and amine (A) which then generates a radical capable of initiating polymerization : M* + A (MA)* --+ Radical Polymer The reaction is similar in principle to that for the photoreduction of aromatic ketones with aliphatic amine~.~' Tetramethyltetrazene (8; R' = R2 = R3 = R4 = Me) is an efficient photo-sensitizer for polymerization of MMA and STY.42 The initiating dimethylamino-radical is electrophilic and reactivities of this radical towards various monomers correlate well with the e (polar) parameters of the vinyl monomers tested.Photopolymerizations using SS'-diphenyl dithi~carbonate,~~ which involve both initiation and termination by the phenylthiyl radical (PhS-) and the cyclic azo-compound 3-acetoxy-3,5,5,-trimethylpyrazoline (1 l), have been described. Me Mixtures of ferrocene and carbon tetrachloride are effective photoinitiators of MMA polymerization by the mechanism shown in Scheme 2.,' (C,H,),Fe + CCl tea+ ***Cl-Ca-CI I I monomer Polymer C-- CCl + (C,HS)2Fe+ + C1-(12) Scheme 2 38 H. G. Heine H. J. Rosenkranz and H. Rudolph Angew. Chem. Internat. Edn.1972, 3 9 T. Nagabhushanam and M. Santappa J . Polymer Sci. Part A - I Polymer Chem., 11 974. 1972 10 151 1 Kinetics and Mechanism of Addition Polymerization 139 Styrene is not polymerized by this system probably owing to a termination reaction with the ferricinium cation (12). Styrene is however polymerized radically in a titanocene dichloride [(Cp),TiCl,] sensitized system.46 This is unusual in that this sensitizer normally polymerizes via a cationic mechanism (e.g. vinyl ethers) but also produces copolymers of 2-chloroethyl vinyl ether and styrene by an apparent radical mechanism. Metal carbonyls and acetylaceto-nates can also act as photo initiator^,^^^^ the mechanism usually involving an abstraction reaction by the photoexcited metal derivative. Initiation of styrene polymerization by high electric fields5' has been shown to involve a cation-radical species.G.p.c. and inhibition data indicate that cationic and free-radical polymerization occur independently and it is proposed that the cation-radical transfers its cationic activity to styrene monomer enabling the resulting growing radical and styrene cation to propagate separately. Tetramethylthiuram disulphide (1 3) is commonly used both as an initiator and Me. Me \ / N-C-S-S-C-N I1 \ S Me / II Me S as an inhibitor of free-radical p~lymerization.~ Incorporation of the sulphur-containing groups in polymers is shown by elemental analysis or even by U.V. spectro~copy.~~ The associated thermal instability of these groups leads to a possible use of these polymers as macromolecular initiators.Sulphur-containing compounds are generally good inhibitors of free-radical polymerization ; thiols have been used as molecular-weight regulator^,^ and in suitable cases dye partition techniques can be used to establish transfer constant^.'^ 'O K. Yokota H. Tomioka T. Ono and F. Kuno J. Polymer Sci. Part A - I Polymer 4 1 4 2 K. Sugiyama T. Nakaya and M. Imoto J. Polymer Sci. Part A - I Polymer Chem., 4 3 K. Tsuda and K. Kosegaki Makromol. Chem. 1972 161 267. 44 T. Nakaya H. Ikeda and M. Imoto Makromol. Chem. 1972 161 241. 4 5 K. Tsubakiyama and S. Fujisaki J. Polymer Sci. Part B Polymer Letters 1972 10, 46 K. Kaeriyama and Y. Shimura J. Polymer Sci. Part A-1 Polymer Chem. 1972 10, 4 7 C. H. Bamford and M. U. Mahmud J.C.S.Chem. Comm. 1972 762. 4 8 C. H. Bamford and A. N . Ferrar J.C.S.Furaday I 1972 68 1243. 49 C. H. Bamford and J. Paprotny Polymer 1972,13 208. '" M. Lambla R. Koenig and A. Banderet European Polymer J. 1972 8 1. " J. Beniska Polymer Sci. (U.S.S.R.) 1971 13 2009. '' J. Beniska E. Staudner and E. Spirk Makromol. Chem. 1972 161 113. 5 3 A. V. Ryabov L. A. Smirnova U. M. Soldatov and L. M. Orlova Polymer Sci. " K. K. Roy D. Pramanick and S. R. Palit Makromol. Chem. 1972 153 71. Chem. 1972,10 1335. S . G. Cohen and H. M. Chao J. Amer. Chem. SOC. 1968,90 165. 1972 10 205. 341. 2833. (U.S.S.R.) 1971 13 165 140 P. Hyde and A . Ledwith A method has been described for calculating transfer constants of very reactive transfer agents (thiols aldehydes) by the use of an integrated Mayo equation, which allows for depletion of transfer agent during rea~tion.’~ Values of the transfer constants for a number of reactive transfer agents in the polymerization of ethylene are given.Nitrobenzenes have been shown to be good inhibitors of the polymerization of vinyl a ~ e t a t e . ~ ~ ’ ~ Reactivities correlate with inductive parameters for -CH,R and -SO,R substituents p-substituents being slightly more reactive than rn-substituents. For groups which show a mesomeric effect (halides keto-groups amines) the p-effect is approximately four times greater than the rn-effect. Nitroso-compounds (ArNO) are also efficient inhibitors of free-radical polymer-i ~ a t i o n ~ * but detailed analysis of the systems may be complicated by side reactions.2,2,6,6-Tetramethyl-4-oxopiperidine 1-oxyl (14) is a stable free radical reported to be a good inhibitor for STY and MMA polymerization. Scavenging of both initiator radicals (Me,CCN) and short polymer chains seems to be very efficient.59 :$7 N I Estimates of AIBN efficiency in these systems were in good agreement with those of other workers (STY f = 0.6; MMA f % 0.5). Ferric nitrate normally an inhibitor has been shown to be an initiator of MMA polymerization when used at low concentration ;60a at high concentrations the ferric salt terminates polymeriza-tion as does ferric chloride in the polymerization of vinyl chloride.60b Model compounds are often used to assess the degree of transfer to polymer in systems which may be taken to high conversion.Vinyl acetate copolymers with fumarate esters are important commercial oil additives ; studies on model compounds (succinate esters and ethyl acetate) indicate that transfer to polymer via the fumarate units is the probable cause of branching in high-conversion 5 5 G. A. Mortimer J . Polymer Sci. Part A-I Polymer Chem. 1972 10 163. 5 6 T. Foldes-Berezhnykh S . Szakacs and F. Tudos European Polymer J . 1972 8 1237. 5 7 T. Foldes-Berezhnykh F. Tudos and S. Szakacs European Polymer J. 1972,8 1247. 5 8 I. Kende L. Sumegi and F. Tudos European Polymer J . 1972,8,1281. 5 9 Y. Miura S. Masuda and M. Kinoshita Makromol. Chem. 1972 160 243. ‘O ( a ) H. Narita Y. Sakamoto and S. Machida Makromol. Chem. 1972 152 143; ( 6 ) W. I . Bengough and N. M. Chawdry J.C.S. Faraday I 1972,68 1807.J . C. Bevington M. Johnson and J . P. Sheen European Polymer J . 1972 8 209 Kinetics and Mechanism of Addition Polymerization 141 Copolymerization.-The analysis of normal low-conversion binary copolymers is well understood and needs no further elaboration. The copolymerization equation has however been extended to account for systems which include acetylenic monomers where differences between radicals (15) and (16) need to be taken into account.62a A modified equation62b enables reactivity ratios in binary -CH=C-CH=C I R I R and ternary copolymerizations to be estimated from residual monomer concen-trations. Solvent effects in copolymerizations may be quite pronounced. The addition of water or glacial acetic acid to the copolymerization of MMA and acrylamide in dimethyl sulphoxide or chloroform changes the reactivity ratios.63 The copolymerization behaviour of MMA and STY is also affected by changes in solvent type.64 Such solvent dependence generally infers some form of complex-ing behaviour in the system either monomer-monomer or monomer-solvent.The effect of the contribution of the charge-transfer complex in the styrene-maleic anhydride system has been e ~ a l u a t e d . ~ ~ In strong donor solvents (acetone THF) there is a lot of solvent-maleic anhydride interaction and the monomer-monomer complex plays little part in the copolymerization. In benzene or CCl, styrene-maleic anhydride interactions are strong and it is suggested that the copolymer-ization is controlled by this complex. The effect of temperature on copolymer composition and microstructure is not easily studied since activation energy differences between the various reactions tend to be small and temperature changes have little effect.Such effects are best studied at low temperatures and only recently have suitable initiators become available. The copolymerization of STY and MMA between + 60 and - 60 "C has been studied using AIBN at +6O"C and the system CoH(N,)(PPh,),-dichloroethane at - 30 and - 60 0C.66 The reactivity ratios are found to fall slightly with decreasing temperature (r = 0.51-4.44; r = 0.46-4.29) leading to a greater degree of alternation and the low-temperature polymers also have a larger degree of syndiotacticity. Maleic anhydride is commonly used to form alternating copolymers with vinyl monomers.It has also been shown to produce high-molecular-weight copolymers with phenyla~etylene~~ and heptafluoroisopropyl methylallyl ether,6 both of 6 2 ( a ) B. A. Zaitsev A. G. Zak R. G. Luchko and G. A. Shtraikhman European Polymer J. 1972 8 1121 ; (6) V. Jaacks Makromol. Chem. 1972 161 161. 6 3 M. Jacob G. Smets and F. de Schryver J . Polymer Sci. Part A - I Polymer Chem., 1972 10 669. 64 G. G. Cameron and G. F. Esslemont Polymer 1972,13,435. 6 5 E. Tsuchida T. Tomono and H. Sano Makromol. Chem. 1972 151 245. 6 6 A. D. Jenkins and M. G. Rayner European Polymer J . 1972,8 221. 6' 6 8 W. L. Wasley and A. G. Pittman J . Polymer Sci. Part B Polymer Letters 1972 10, H. Block M. A. Cowd and S. M. Walker Polymer 1972 13 549. 279 1 42 P.Hyde and A . Ledwith which are difficult to homopolymerize to high molecular weight. Terpolymer-izations involving maleic anhydride STY and MMA or MA do not conform to the normal terpolymerization expression^,^^ and it is assumed that complex formation between STY and maleic anhydride is responsible for the anomalous behaviour. Terpolymerization of maleic anhydride with ethyl vinyl sulphide and ethyl vinyl ether has also been described;70" both monomers complex with maleic anhydride to a small extent and it was found that the reactivity of free vinyl sulphide to PMAn- was 4-6 times greater than that of free ethyl vinyl ether. Vinyl sulphides are also reported as compolymerizing thermally with weakly electron-accepting monomers such as MMA diethyl maleate and ethyl acryl-ate.70b Alternating copolymers may also be prepared by the copolymerization of an electron-rich olefin with an electron-deficient olefin in the presence of a Lewis acid.By this method alternating copolymers of STY and 1-substituted bicyclo-butanes [e.g. (17)] have been ~repared.~' The mechanism is thought to involve the interaction of a complexed growing radical with both monomer types which are then incorporated into the chain (Scheme 3). OMe C=O,ZnCl + CH,=CH 0 j)-3\~=o,ZnC12 U ' OMe (17) OMe OMe I Scheme 3 Addition of zi'nc bromide to the STY-diethyl fumarate system gives rise to 1 1 alternating copolymers for both ele~troinitiated~ and ph~toinitiated~~ systems. Similarly zinc chloride induces a 1 1 copolymerization of acrylonitrile and b~tadiene,~* although here the reaction is complicated by the formation of significant amounts of the cyclo-adduct of the two monomers 4-cyanocyclo-hexene.6 9 J. C. Bevington and C. Nicora Polymer 1972 13 249. 70 H. Inoue and T. Otsu ( a ) Makromol. Chem. 1972,153,37; (6) ibid. p. 21. H. K. Hall jun. and J. W. Rhoades J . Polymer Sci. Part A - I Polymer Chem. 1972, 10 1953. 72 D. C. Phillips D. H. Davies and J. D. Smith Makromol. Chem. 1972 154 317. 73 D. C. Phillips D . H. Davies and J. D. Smith Makromol. Chem. 1972 154 321. 7 4 W. Kuran S. Pasynkiewicz and 2. Floriahczyk Makromol. Chem. 1972 162 53 Kinetics and Mechanism of Addition Polymerization 143 Copolymerizations of vinyl monomers with sulphur dioxide give 1 1 alternat-ing copolymers (polysulphones) and can be initiated by conventional free-radical techniques.Polymerization of SO and but-1-ene in the gas phase can be initiated by electron radiation to give poly(but-1-ene sulphone) which has the repeat unit (18).” In the gas phase the ceiling 0 II I II Et 0 -CH2 -CH-S-(18) temperature (temperature at which propagation and depropagation reactions have equal rates and no polymer-ization occurs) is about 60 “C lower than it is in the liquid phase. The copolymer-ization of norbornene (19) and SO has been thought to be ~pontaneous,~~ initiation supposedly occurring via a biradical (20) which similar species to propagate a biradical chain (Scheme 4). then combines with Recent experiments combination n l 1 18 Scheme 4 using highly purified norbornene suggest that although the polymerization is extremely rapid even in the presence of very small amounts of added initiator, initiation in the ‘spontaneous’ reaction occurs via peroxidic i m p u r i t i e ~ .~ ~ The exact nature of the regulating mechanism for alternation in these systems is not known ; studies on styrene7 and chloroprene” copolymerization and various 7 5 J . R. Brown and J. H. O’Donnel J . Polymer Sci. Part A-1 Polymer Chem. 1972, 10 1997. 7 6 N. L. Zutty C. W. Wilson G. H. Potter D. C. Priest and C. J. Whitworth J . Polymer Sci. Part A General Papers 1965 3 278 1. 7 7 G. Sartori and R. D. Lundberg J . Polymer Sci. Part B Polymer Letters 1972,10 583. 7 8 M. Matsuda M. Iino T. Hirayama and T. Miyashita Macromolecules 1972 5 240.7 9 M. Matsuda and Y . Hara J . Polymer Sci. Part A-I Polymer Chem. 1972 10 837 144 P . Hyde and A . Ledwith terpolymerizationss0~8 have shown that although certain monomers do form complexes with SO, such complexes are unlikely to be involved in the propaga-tion steps. The copolymerizations of styrene and various a-substituted ~ t y r e n e ~ ~ ~ . ~ have been shown to be normal although retardation of rate and chain transfer occur in some systems. Of particular interest is the styrene-a-methylstyrene system where the reaction scheme needs to be modified to account for the rever-sible addition of P(a-MeSTY). to its own monomer at the temperatures used (Scheme 5). At higher temperatures (1 50 "C) reaction (2) becomes reversible, Me Me Me Me I I I I I Ph I Ph H Me H Me I I I I I Ph Ph Ph -CH,-C* + CH -C -CH,-C-CH,-C* (1) I Ph ,- I Ph -CH,-C.+ CH -C -CH,-C-CH,-C* (2) I Ph I ,- I Scheme 5 the equilibrium constant being approximately 1/30th that for a-methylstyrene homopolymerization i.e. the equilibrium lies well to the left. a-Methylstyrene-MMA copolymerization between ceiling temperatures has also been investi-gated.84b Styrene-divinylbenzene copolymers form the basis for many commercial ion-exchange resins. It has been shown that at very low conversion with only small quantities of divinylbenzene large numbers of rings are formed by intramolecular capture of pendant vinyl groups (Scheme 6).85 Intermolecular cross-linking will Scheme 6 M. Iino K. Seki and M. Matsuda J . Polymer Sci.Part A - I Polymer Chem. 1972, 10 2993. M. Matsuda M. Iino and S.-I. Numata J . Polymer Sci. Part A-I Polymer Chem., 1972 10 829. 8 2 J. P. Fischer Makromol. Chem. 1972 155 211. 8 3 J. P. Fischer Makromol. Chem. 1972 155 227. 8 4 (a) J. P. Fischer and W. Luders Makromol. Chem. 1972 155 239; (6) M. Izu K. F. O'Driscoll R. J. Hill M. J. Quinn and H. J. Harwood Macromolecules 1972 5 90. 8 5 B. Soper R. N . Haward and E. F. T. White J . Polymer Sci. Part A-I Polymer Chem., 1972 10 2545 Kinetics and Mechanism of Addition Polymerization 145 occur when the polymer concentration becomes sufficiently large. Di-isopro-penyl benzene is similar to divinylbenzene and forms cross-linked copolymers with STY in the same fashion.86 Acrylonitrile (AN) is an important monomer for the production of artificial fibres and copolymerization of AN with monomers containing functional groups is useful in improving d ~ e a b i l i t y .~ ~ Reactivity ratios of several acrylates towards AN have been determined88 and lie in the order a-Br-methyl acrylate > a-C1-methyl acrylate > MMA > MA. Copolymerization of acrylamide with a number of cis and trans 3-substituted acrylic acids8’ has shown that the relative reactivity of the cis-isomer is larger than the trans- when the substituent on the acid is electron-donating but that the order is reversed when the substituent is electron-withdrawing. In this system steric effects on reactivity are unimportant, and it is suggested that in the general case of 1,2-distributed ethylenes the order of reactivity of cis- and trans-isomers can be predicted from the difference in inductive parameters for the substituents.In copolymerizations of acrylic acid salts with acrylamide the nature of the metal cation has been shown to have a significant effect upon the monomer reactivity ratios and overall copolymerization rates.” This is ascribed to inter-actions between the growing radical and the fully dissociated acrylate anion, which are modified by the bonding of the metal cations (Ba2+ Sr2+ Ca2+) to acrylate segments in the polymer. Diallyl compounds are known to be unreactive in copolymerizations with styrene ;91 determinations of chain-transfer constants92 show that hydrogen abstraction by polystyryl radical to produce the stable ally1 radical (21) is an important process in these systems.PSTY- + H2C=CH-CH2R -+ PSTY-H + H2C=CH-eHR (3) (21) N-Vinyl compounds are very reactive in free-radical polymerization. Molecu-lar orbital calculations have shown that the various N-vinyl monomers should have similar Q and e parameters i.e. the H,C=CH-N < structure is the major contributor to the reactivity of these corn pound^.^^ As a test of this hypothesis, it is shown that copolymerization curves of STY-NVC and STY-N-vinyl-pyrrolidone are superimposable. Formation of a polyester by free-radical copolymerization of cyclohexene and formic acid in the presence of iodine and hydroperoxides is the first reaction of this type reported to yield high-molecular-weight The repeat unit 8 6 H. S. Kolesnikov A.-S. Tevlina L.Ye. Frumin and A. I. Kirilin Polymer Sci. ( U . S . S . R . ) 1971 13 625. *’ U. Bahr H. Wieden H.-A. Rinkler and G. Nischk Makromol. Chem. 1972 161 1 . * * J . Szaflco and E. Turska Makromol. Chem. 1972 156 311. 8 9 K. Matsuo and S. Machida J . Polymer Sci. Part A-I Polymer Chem. 1972 10 187. 90 K. Plochocka and T. J. Wojnarowski European Polymer J. 1972 8 921. 9 1 For example see A. Matsumoto and M. Oiwa Kogyo Kagaku Zusshi 1970,73 228. 9 2 A. Matsumoto and M. Oiwa J . Polymer Sci. Part A-I Polymer Chem. 1972,10 103. 9 3 I . Negulescu D. Feldman and Cr. Simionescu Polymer 1972 13 149. 94 C. G. Gebelein J . Polymer Sci. Part A-I Polymer Chem. 1972 10 1763 146 P. Hyde and A . tedwith in the polymer seems to be (22) retaining the original unsaturation of the cyclo-hexene.The exact mechanism of the polymerization is not yet known but is suggested as involving interaction of a cyclohexene-iodine complex with C 0 2 H radicals. Ph~toinitiation~’ of chloroprene polymerization by the system manganese carbonyl-poly(viny1 trichloroacetate) can be used to prepare cross-linked net-works of known constitution. Telechelic copolymers of chloroprene isoprene, and butadiene with p-chlorostyrene may be prepared by use of appropriately substituted azo-initiators ; chain extension via the functional end-groups is then possible and it is suggested that these materials may be of use as encapsulation resins.96 The copolymerization of styrene or maleic anhydride with a monomer (23) bearing an inhibitor function is surprising but may lead to polymers with improved oxidation re~istance.~’ Olefin (23) is only of low reactivity in copoly-CMe, H2C=CH-O-CH2-CH2-O-C -QOH (23) CMe, merization with STY (monomer 2) r l = 0.0; r 2 = 30.In the copolymerization of (23) with MMA,98 it was found that initiation by AIBN gave a normal copoly-merization but initiation by cumene hydroperoxide gave very little polymeriza-tion owing to the preference for the ketyl radical (24) to abstract the phenolic hydrogen of the monomer (Scheme 7). Me Me I Me (24) Ph-C-0. I + R 4 ; H + Ph-C-OH+ I R I Me CMe.3 CMe, R = H2C=CH-O-CHzCH2-02C-Scheme 7 9 5 J. Ashworth C. H. Bamford and E. G. Smith Polymer 1972 13 57. 9 6 S. F. Reed jun. J . Polymer Sci. Part A-1 Polymer Chem. 1972 10 2025. 9’ 9 8 M. Kato and Y.Nankano J . Polymer Sci. Part B Polymer Letters 1972,10 157. M. Kato and Y. Takemoto J . Polymer Sci. Part B Po[ymer Letters 1972 10 489 Kinetics and Mechanism of Addition Polymerization 147 Ethylenes are best polymerized with co-ordination catalysts but the free-radical copolymerization of ethylene and tetrafluoroethylene has been shown to give a 1 1 alternating copolymer of high chemical and thermal stability.99 The alternating tendency in this system is extremely high ; (r1r2 is 0.O001 at - 30 "C and 0.006 at + 65 "C) and polymers tend to be fairly crystalline (50-60 %). 2 Anionic Polymerization Initiation of anionic polymerization is normally via simple unifunctional low-molecular-weight organometallics (e.g. n-butyl-lithium) or bifunctional species such as a-methylstyrene tetramer (dianion).Significant differences in rates of initiation and propagation cause deviations from the ideal Poisson distribution for the molecular weight of the resulting polymer. Hacker''' has shown that, when a bifunctional initiator is used the dispersity (M,,,/M,) of the polymer should not exceed 1.4 even when k,/ki is as large as lo6. The sodium adduct of pyridine N-oxide has been shown to be capable of initiating the anionic polymerization of STY MMA and acrylonitrile."' From a study of the reaction products of sodium and pyridine N-oxide it was concluded that the active species in initiation are pyridyl 2,2'-bipyridyl and 4,4'-bipyridyl anion-radicals. Lithium di-n-butyl cuprate' O 2 polymerizes MMA to a polymer of tacticity similar to that produced via conventional organolithium initiators.Attempted MMA copolymerization with STY gave polymers containing no STY a result again consistent with conventional anionic initiation.'03 The cuprate salt is exceptional in that it will polymerize NVC copolymerizations with MMA and vinyl acetate show that a radical mechanism is not operative and it is suggested that the NVC anion is co-ordinated by the copper enabling a nucleophilic addition to a co-ordinated monomer molecule to take place ; see (25). - -9 9 100 1 0 1 1 0 2 103 R I I - - * ' - * - . - I p!., -cH,-CH ,,=-' .'- HC=CH, M. Modena C. Garbuglio and M. Ragazzini J . Polymer Sci. Part B Polymer Letters, 1972 10 153. H. Hocker Makromol. Chem. 1972 157 187. K. Yamaguchi T.Yoshida and Y. Minoura J . Polymer Sci. Part A - I Polymer Chem., 1972 10 2501. M. E. Londrigan and J. E. Mulvaney J . Polymer Sci. Part A - I Polymer Chem., 1972 10 2487. W. Fowells C. Schuerch F. A. Bovey and F. P. Hood J . Amer. Chem. SOC. 1967, 89. 1396 148 P. Hyde and A . Ledwith The first photo-initiated anionic polymerization has been reportedlo4 and involves the polymerization of nitroethylene in THF. From a study of the wavelengths of light which activate the polymerization it is concluded that initiation occurs via a photoexcited THF-nitroethylene charge-transfer complex. Reports of initiation by phosphorous ylides,'05 metal xanthates,lo6 and potas-sium-graphite inclusion comp~unds'~ have also appeared. Because of the variety of propagating species (ion pairs contact ion pairs, solvent-separated ion pairs free ions) which may occur in a given system rates of polymerization for a given monomer-initiator system are found to be extremely solvent dependent.For the polymerization of STY in tetrahydropyran it has been confirmed that the large differences in rate observed between this system and other STY-ether systems are attributable to shifts in the equilibrium between contact ion pairs solvent-separated ion pairs and free ions rather than to any solvent effect on the individual rate constants for each ionic species."* The type of ionic species present in a system can be determined from studies of conductivity which may be supported by U.V. spectral data."'. '' using a variety of initiators with THF and 2-methyl-THF as solvents show that the free-ion rate constants for derivatives (0- rn- p-methyl- and p-isopropyl-STY) are generally smaller than for STY and also that these rate constants are reduced by changing from THF to 2-methyl-THF.Hammett plots for the propagation rate constants were dependent on the system for all but the free-ion rate constants. It was concluded that in the case of sodium salts of living polymers the value of k is a reflection of the dissociation state of the polymer ion whereas for the caesium salts the major influence on k is the reactivity of the free ion. Oligomers of or-methylstyrene may be used as initiators for anionic polymeriza-tion. Ageing of these compounds has been shown to result from either hydride transfer to the counter ion or hydrogen transfer from solvent (Scheme 8).'12 Olefins (26) and (27) may then react with further oligomers uia hydrogen transfer.The rate of polymerization of MMA initiated by the disodium salt of a-methyl-styrene tetramer is found to depend largely on the method of initiation.' When the monomer is added in one step the polymerization proceeds mainly via Kinetic studies on the polymerization of styrenes,' l o 4 M. hie S. Tomimoto and K. Hayashi J . Polymer Sci. Part B Polymer Letters 1972, 10 699. H. Klippert and H. Ringsdorf Makromol. Chem. 1972 153 289. 1972 10 63. 10 1267. L. L. Bohm and G. V. Schulz Makromol. Chem. 1972,153 5 . l o 6 K. Yamaguchi 0. Sonoda and Y . Minoura J . Polymer Sci. Part A- I Polymer Chem., l o ' I. M. Panayotov and I.B. Rashkov J . Polymer Sci. Part A-1 Polymer Chem. 1972, l o g H. Hirohara M. Nakayama R. Kawabata and N . Ise J.C.S.Faraday I 1972 68 51. D. K. Polyakov N . I. Baranova A. R. Gantmakher and S. S. Medvedev Makromol. Chem. 1972 152 1 . B. J. Schmitt Makromol. Chem. 1972 156 243. P. E. M. Allen R. P. Chaplin and D. 0. Jordan European Polymer J . 1972.8 271. l o H. Hirohara M. Nakayama and N . Ise J.C.S. Faraday I 1972,68 5 8 Kinetics and Mechanism of Addition Polymerization Me Me I / I I \ -c-c=c + /" Ph H Ph NaH (26) M e H Me I l l I l l I l l Ph H Ph \ Ph H Ph -C-C-C-Na+ + -C-C-C=CH + NaH \" M e H Me n I l l H Ph H Ph 149 Scheme 8 solvent-separated ion pairs (k > 25 1 mol-' s-' at 200 K) whereas initiation via the two-step technique (addition of a trace of monomer followed shortly after by the bulk) results in propagation via contact ion pairs ( k = 1.2 x 10- ' 1 mol- ' s-' at 283 K).The discrepancy between the two types of initiation is not observed at higher temperatures where presumably relaxation of solvent-separated ion pairs to contact ion pairs occurs more rapidly. MMA homopolymerization' l4 and copolymerization with STY '' initiated by suspensions of alkaline-earth metals has been shown to involve parallel radical and anionic mechanisms. However initiation of diene copolymerization by these metals seems to occur via a purely anionic route.' l 6 Branching in MMA polymerization occurs by reaction at an ester group on monomer or polymer. A viscometer study has shown that n-butyl-lithium-initiated polymerization results in such branching the frequency of which is independent of conversion up to very high conversion and increases with in-creasing temperature.' ' Polymerizations initiated by lithium t-butoxide give linear polymers ascribed to co-ordination of alkoxide at the growing centre preventing reaction with ester groups.Polymerization by t-butoxide ion is inhibited by p-benzoquinone' at initiator inhibitor ratios < unity suggesting some form of addition reaction of t-butoxide and benzoquinone. When excess initiator is used polymerization proceeds but the rate increases and the polymer stereochemistry changes under the influence of this adduct. In general anionic polymerization of methacrylic esters gives highly syndiotactic polymers,' ' the 'I4 C.Mathis and B. Francois Makromol. Chem. 1972 156 7. 'Is C. Mathis and B. FranGois Makromol. Chem. 1972 156 17. 'I6 P. Maleki and B. Francois Makromol. Chc~nr 1972 156 31. I " J. Trekoval and P. Kratochvil J . Polymer Sci. Part A-1 Polymer Chem. 1972 10, 1391. P. VlEek and J. Trekoval Coll. Czech. Chem. Comm. 1972 37 1918. J. Junquera N. Cardona and J. E. Figueruelo Makromol. Chem. 1972 160 159 150 P . Hyde and A . Ledwith degree of syndiotacticity increasing with the gegen-ion in the order Li+ > Na+ > K+ and also to a small extent with the ester group (methyl x ethyl < n-butyl). Acrylonitrile (AN) is polymerized by triphenylphosphine in DMF at 30 O C . 1 2 0 The initiation mechanism involves zwitterion formation from PPh and AN, followed by hydrogen abstraction from monomer (Scheme 9) ; the resulting anion (28) is the effective initiator.Ph,P + H,C=CHCN -+ Ph,;-CH,-CHCN Polymer C- H,C=eCN + Ph,h-CH,CH,CN Scheme 9 H,C=CHCN monomer (28) Dienes are quite conveniently polymerized by anionic means. l,l'-Bis(tri-fluoromethyl)buta-l,3-diene can be polymerized by butyl-lithium to give a living polymer.121 Although this will not add butadiene to give a block copoly-mer propagating butadiene will add the fluorinated monomer. 1 -Ferrocenylbuta-1,3-diene is also polymerized by butyl-lithium.122" Polydispersion in this system is high and increases with molecular weight suggesting some form of activity transfer to the ferrocenyl nucleus (29) which cannot then propagate the chain. The preparation polymerization and copolymerization of 1-cyanobutadiene have also been reported.' 22b H H I I -C-CH=CH-CH,Li+ --* -C-CH=CH,-CH, Fe Living ends of polymers are found to be associated in hydrocarbon solvents and this may cause complications in the interpretation of kinetic orders of propagation reactions.Light-scattering and viscometric studies have shown that l Z o V. Jaacks C. D. Eisenbach and W. Kern Makromol. Chem. 1972 161 139. l Z 1 M. H. Kaufman J . Polymer Sci. Part A - I Polymer Chem. 1972 10 455. l z 2 ( a ) D. C . Van Landuyt J . Polymer Sci. Part B Polymer Letters 1972 10 125; (6) R. Worley and R. N. Young European Polymer J . 1972 8 1355 Kinetics and Mechanism of Addition Polymerization 151 polystyryl-lithium has an association number 2 in cyclohexane but for the corresponding polybutadienyl and polyisoprenyl salts the value is 4.'23 Pre-viously reported discrepancies in the values for the latter salts are explained by the formation of dimers at low concentration.Use of polar modifiers' 244 in butadiene polymerization affect the polymer microstructure ; suitable choice of modifier concentration and polymerization temperature allows the preparation of polybutadienes with any desired 1,2 microstructure. A similar study has been carried out with 2-~henylbutadiene,'~~' where polar modifiers induce high percentages of pendant vinyl groups in the polymers. Polymer microstructure is also affected by the nature of the interaction between the growing anion and the gegen-ion and has been studied for a number of butadienes.l2' The effect of solvent and gegen-ion in isoprene polymerization is also to influence the rate of polymerization and polymer microstructure.126 Free ions give a polymer of structure 1,4- 25 % 1,2- 33 % 3,4- 42 % independent of the cation.When the solvent favours propagation via contact ion pairs the cation is of extreme importance. Changing from Li+ to Cs' markedly influences the relative amounts of 1,4- (highest for Cs') and 3,4- (highest for Li') structures. This is interpreted (Scheme 10) in terms of different co-ordination of the diene with the small Li' (30) and large Cs+ (31) ions. _+ P Li+ -+ P (30) 3,4-addition cs+ . (31) 1,4-addition Scheme 10 Initiation of isoprene polymerization with l,l'-diphenyl-n-hexyl-lithium127 gives polymers of high 1,4 content predominantly in the cis-form.Determination of the activation energy of propagation gave a value of 19 kcal mol- and the 1 2 3 124 1 2 5 1 2 6 1 2 7 D. J. Worsfold and S. Bywater Macromolecules 1972 5 393. ( a ) T. A. Antkowiak A. E. Oberster A. F. Halasa and D. P. Tate J . Polymer Sci., Part A- I Polymer Chem. 1972 10 1319. (b) R. J. Ambrose and W. L. Hergenrother, Macromolecules 1972 5 275. M. Morton L. A. Falvo and L. J. Fetters J . Polymer Sci. Part A-I Polymer Chem., 1972 10 561. A. Essel and Q. T. Pham J . Polymer Sci. Part A-1 Polymer Chem. 1972 10 2793. J. M . Alvariiio A. Bello and G. M. Guzman European Polymer J . 1972 8 53 152 P . Hyde and A . Ledwith polymerization is first order in monomer but only of order 0.25 with respect to total polyisoprenyl-lithium indicative of the association of the living anions.Terminally functional polybutadienes have been prepared by the reaction of living polybutadiene and toluene di-isocyanate (TDI),' 28 giving isocyanate-terminated polymers capable of chain extension with caprolactam to give butadiene-nylon 6 block copolymers or with excess TDI and diamines to give butadiene-urea block copolymers. Polybutadienes with hydroxyl end-groups may be made by end-capping with ethylene oxide and subsequent acidic hydro-l y s i ~ . ' ~ ~ Because of its use in nylon manufacture caprolactam polymerization is of basic interest. Metal cations'30 play an important role in the polymerization, owing to complex formation and can strongly retard or even inhibit polymeriza-tion.Viscometric parameters have been given for molecular-weight determina-tions in cresol and H2S0,;'31 comparison with osmometric data indicates that branching is not uncommon. Methods for determining the number of keto-groups in polymers'32 and the content of catalytically active bases'33 have also been given. The sodium alcoholate-initiated polymerization of E-caprolactone' 34 and its ABA-type copolymerization with ethylene oxide' 35 have been reported. Pyrrolidone is similar to caprolactam and may be polymerized using a variety of initiators. '36 Copolymerization with caprolactam has been described ;' the effect of increasing the temperature (70-200 "C) is to decrease the pyrrolidone content of the polymers. Amongst the many other polymerizations reported are those of l-vinyl-pyrene,' 38 isopropenyl-substituted pyridine oxazole and thiazole,' 39 maleic anhydride initiated by pyridine bases or phosphines,' 40 and acryloyl- and methacryloyl-verdazyls (32 ; R = acryloyl or metha~ryloyl).'~' This last case is of great interest since it incorporates a stable free radical into the polymer with consequent antioxidant and/or semiconductor properties.2-Vinylpyridine is polymerizable anionically and conductometric and spectrophotometric studies have shown secondary ionic species (trienyl carb-anions or nitranions) to be significant by-products of the initiation re-12' W. L. Hergenrother and R. J. Ambrose J . Polymer Sci. Part B Polymer Letters, 1972 10 679. S. F. Reed jun. J . Polymer Sci.Part A- I Polymer Chem. 1972 10 1187. 1 3 0 R. Puffr and J. Sebenda European Polymer J . 1972 8 1037. 1 3 ' C. V. Goebel P. Cefelin J. StehliEek and J. Sebenda J . Polymer Sci. Part A - I , Polymer Chem. 1972 10 1411. J. StehliEek P. Cefelin and J. Sebenda Coll. Czech. Chem. Comm. 1972 37 1926. 1 3 3 J. Sebenda and V. Koufil European Polymer J . 1972,8,437. 1 3 4 R. Perret and A. Skoulios Makromol. Chem. 1972 152 291. 1 3 5 R. Perret and A. Skoulios Makromol. Chem. 1972 156 143. 1 3 6 G. Schirawski Makromol. Chem. 1972 161 57. 1 3 ' G. Schirawski Makromol. Chem. 1972 161 69. 1 3 ' J. J. O'Malley J. F. Yanus and J. M. Pearson Macromolecules 1972 5 158. 1 3 9 K. Yagi T. Miyazaki H. Okitsu F. Toda and Y. Iwakura J . Polymer Sci. Par1 A - I , Polymer Chem. 1972 10 1149.H. Zweifel J. Loliger and T. Volker Makromol. Chem. 1972 153 125. Y . Miura M. Kinoshita and M. Imoto Makromol. Chem. 1972 157 51. 14 Kinetics and Mechanism of Addition Polymerization 153 Ph / \ Ph 143 Copolymerization of 2-vinylpyridine with propylene sulphide has been r e p ~ r t e d ; ' ~ ~ ~ ' ~ ~ here initiation by biphenylsodium results in the formation of pyridyl ion-radicals which dimerize ; subsequent polymerization gives 4,4'-bipyridyl units in the polymer chain (cf. ref. 101). The polymerization of vinyl methacrylate and vinyl acrylate initiated by n-butyl-lithium proceeds via the acrylate double bond only to give linear poly-mers of the type fCH2-C(R)(C0,CH=CH2)+,,.'46 Calibration of i.r. pro-cedures with these polymers enables estimates to be made of the extent of cycliza-tion during the free-radical polymerization.Unsaturated aldehydes have been polymerized by the use of anion-radicals of aromatic carbonyl corn pound^.'^^^'^^ The suggested initiation mechanism is one of electron transfer to monomer but analyses for regenerated ketone are low (generally < 50 %) owing to combination of monomer and ketone to give (33) (Scheme 11). 2Ph2c-0- + Me-CH=CH-CHO + Ph2C0 + Me CH 0 \ / \ * * . ; 2 - ' CH ,e'-'.,CH' '**--' I / c-0 / I OH Me /CH2 / CH CH Ph Ph I I /c- 0 Ph I Ph (33) Scheme 11 14' M. Tardi and P. Sigwalt European Polymer J . 1972 8 137. 1 4 3 M. Tardi and P. Sigwalt European Polymer J. 1972 8 151. A. Gourdenne Makromol. Chem. 1972 158 261. 1 4 5 A. Gourdenne Makromol.Chem. 1972 158 271. 146 W. Fukuda M. Nakao K. Okumura and H. Kakiuchi J . Polymer Sci. Part A-1, 14' I. M. Panayotov and I. B. Rashkov Makromol. Chem. 1972 154 129. 1 4 * I . B. Rashkov and I. M. Panayotov Makromol. Chem. 1972 151 275. Polymer Chem. 1372 10 237 154 P. Hyde and A . Ledwith The polymerization of succinonitrile gives polymers whose structure depends on the initiator. 149 Either semiconducting (sodium methanolate) or dielectric (potassium t-butylate) polymers may be obtained. Metal complexes of nitriles or ketones are found to initiate the polymerization of cyclic s ~ l p h i d e s . ' ~ ~ Initi-ation by aromatic nitrile dianions proceeds via electron transfer but initiation by the corresponding anion-radical varies with the monomer ; styrene sulphide (34) undergoes an electron-transfer reaction but ethylene sulphide (35) adds.ArCN- + Ph-CH -CH -+ ArCN + Ph-bH-CH,-S-\S/ (34) - CH -+ ArC=N-CH,-CH,-S-H2C\ / Arc" + S (35) Olefin oxides are polymerizable anionically and recent studies on propylene' and 1,2-butylene oxides'" have shown that in DMSO the order of reaction with respect to initiator is high (1.7-1.8) owing to propagation via both free ions and ion-pairs whereas in THF-DMSO mixtures only ion pairs are involved and the order of reaction for initiator is unity. The effects of substituents'53 on ethylene oxide polymerization and its copolymerization with propylene oxide' 54 have been described. Copolymerization.-Although anionic formation of block copolymers is well known and still extensively studied comparatively little effort is expended in the study of copolymerization systems which result in the distribution of the mono-mers along the whole length of the chain.Copolymerization of acrolein with aldehydes' gives unsaturated polyacetals since the acrolein is incorporated via its carbonyl double bond i.e. R- + CH,=CH-CH=O + R-CH(CH=CH,)-O- -P polymer These polymers have greater stability to photochemical and oxidative cross-linking than acrolein homopolymer. Anionic copolymerizatior of various alkyl dibromides (RX,) with STY or a-methylstyrene gives regular copolymers of structure +monomer-monomer-R j-, 149 D. Wohrle Makromol. Chem. 1972 160 83. l S o I. M. Panayotov and I . V. Berlinova Makromol. Chem. 1972 154 139. 1 5 1 L.P. Blanchard V. Hornof J. Moinard and F. Tahiani J . Polymer Sci. Part A-1, Polymer Chem. 1972 10 3089. L. P. Blanchard K. T. Dinh J. Moinard and F. Tahiani J . Polymer Sci. Part A - I , Polymer Chem. 1972 10 1353. 1 5 3 V. A. Ponomarenko A. M. Khomutov S. I. Il'chenko and A. V. Ignatenko Polymer Sci. (U.S.S.R.) 1971 13 1735. 1 5 4 G. A. Gladkovskii and Ye. V. Ryzhenkova Polymer Sci. (U.S.S.R.) 1971 13 723. I s 5 J. L. Mateo and R. Sastre Makromol. Chem. 1972 157 141 Kinetics and Mechanism of Addition Polymerization 155 when the feed has 2 1 monomer dibromide molar stoicheiometry,' 56 which become less regular and richer in monomer as the proportion of dihalide de-creases. Because of the reactivity of styrene in anionic polymerization its copolymerization is complicated by formation of homopolymer after consump-tion of the dihalide component when this is present only in small amounts.Similar studies have been reported for butadiene and isoprene.' The copolymerization of cyclic sulphides and aryl or alkyl isothiocyanates (36) is reported to yield a regular alternating copolymer (Scheme l2).ls8 Isothio-NR' S NR' R2 II / \ II I -C-S- + H2C-CH --* -C-S-CH2-CH-S-I (36) R2 R2 R2 NR ' I I II -CH2-CH-S- + R'-N=C=S --* -CH,-CH-S-C-S-(37) Scheme 12 cyanates do not homopolymerize anionically but appear to be reactive enough to scavenge the ring-opened sulphide (37) before it can add a second sulphide monomer unit. 3 Cationic Polymerization The cationic polymerization of monomers initiated by Friedel-Crafts halides has been supposed always to require the presence of small amounts of a co-catalyst (water HCl alkyl halides).Kennedy'"" has recently made a critical evaluation of much of the literature pertinent to this concept and has concluded that there are in fact many systems which will polymerize in a wholly reproducible fashion in the absence of co-catalyst. It was proposed that the self-initiation reaction shown in Scheme 13 occurs. Key factors in this mechanism are basicity I l l I l l I I I I C=C-CH + MX C=C-C+MX,H-Scheme 13 of the Lewis acid MX, facilitating the hydride-abstraction reaction and the stability of the resulting allylic cation. Initiation is therefore not possible when the monomer does not have an allylic hydrogen and in support it is found that a-methylstyrene is polymerized by AlEt,Cl whereas STY is not.A. V. Cunliffe W. J. Hubbert and D. H. Richards Makromol.Chem. 1972 157 23. 15' A. V. Cunliffe W. J. Hubbert and D. H. Richards Makromol. Chem. 1972 157 39. G. Belonovskaya Zh. Tchernova and B. Dolgoplosk European Polymer J. 1972, 8 35. ( a ) J. P. Kennedy J . Macromol. Sci. Chem. 1972 A6 329; (6) N. A. Ghanem and M. Marek European Polymer J . 1972 8 999 156 P. Hyde and A . Ledwith Further experimental support rejecting the necessity for co-catalytic activity comes from a study of the polymerization of isobutene initiated by AlBr or BF under anhydrous conditions;' 5 9 b TiCl, however was found to require the addition of water. The use of tritiated water indicates that no incorporation of protons occurs during the initiation process and it is proposed that the function of any water present is to solvate (and so stabilize ion-pair formatioil ~ .g . "2: TiCI . Studies of the effect of water on the polymerization of styrene in various solvents indicate that the primary effect is to influence the equilibria between contact ion pairs solvated ion pairs and free ions for the initiator.160,'61 Overall rates of polymerization show maxima as solvent polarity and water concentration are changed. n-Alkyl and benzyl halides have been used as co-catalysts in the aluminium iodide-initiated polymerization of isobutene ; 16* their function is not simply co-catalytic however and it appears that a halide-exchange reaction occurs between the n-alkyl halides and aluminium iodide to give catalytically active products.Cationic polymerization may be electro-initiated using various metal salts as electrolytes in polar solutions. The electro-initiated polymerization of NVC using zinc bromide in acetone is found to produce low-molecular-weight polymer having narrow di~tribution.'~~ Changing the rate of initiation and electrolyte concentration has little effect on either molecular weight or distribution. Electro-initiation of styrene polymerization yields a polymer suggested as having 'living' character with molecular weight governed by transfer to monomer.'64 Values of k depend on the type of initiation continuous electrolysis gives k z 4.2 1 mol- ' min- whereas polymerization after the current has stopped has k x 1.6 1 mol-' min-'.Electro-initiation of n-butyl vinyl ether'65 and ethyl and isobutyl vinyl ether'66 polymerization results in similar behaviour. Transfer to monomer and solvent govern the molecular weight although here th, systems are not thought to be 'living'. Vinyl ethers are readily polymerizable by cationic mechanisms ; polymerization of alkyl vinyl ethers can be induced by the presence of acceptor molecules whose function is to complex with the ether electron transfer then giving an anion-radical and an initiating cation-radi~a1.I~~ The order of reactivity of a number of alkyl vinyl ethers was found to be t-butyl > isopropyl > ethyl % n-butyl x isobutyl which corresponds to the order of inductive effects of the alkyl groups. Pure tetracyanoethylene (TCNE) a strong acceptor molecule did not induce polymerization preferring instead to add to the vinyl ethers to form cyclobutanes.Samples of TCNE contaminated with tricyanoethanol however were sufficiently acidic to initiate polymerization. 160 M. KuEera J. Svabik and K. Majerova Coll. Czech. Chem. Comm. 1972 37 2004. 1 6 1 M. KuEera J. Svabik and K. Majerova Calf. Czech. Chem. Cornm. 1972,37,2708. 1 6 2 P. Lopour J. Pecka and M. Marek Makrornof. Chern. 1972 151 139. 1 6 3 D. C. Phillips D . H. Davies and J. D. B. Smith Macromolecules 1972,5 674. 164 G . Meqgoli and G . Vidotto European Polymer J . 1972 8 661. G. Mengoli and G. Vidotto European Polymer J. 1972 8 671. 1 6 6 G. Mengoli and G. Vidotto Makromof. Chem. 1972 153 57. 1 6 ' R. F. Tarvin S. Aoki and J. K. Stille Macromolecufes 1972 5 663 Kinetics and Mechanism of Addition Polymerization 157 Anilinium hexafluoroantimonate (PhNH,+ SbF,-) is reported to be a good initiator for the polymerization of ethyl vinyl ether.',* In common with hexa-chloroantimonate salts the anion is large chemically stable and has no reaction with growing cations.Catalysis is very efficient concentrations as low as lo-, mol % producing nearly quantitative yields of polymer. Stereoregular polymers may be prepared from butenyl ethers (EtCHZCHOR) at low temperature.' 69 Crystalline polymers were obtained from the methyl and ethyl ethers the same stereochemistry being obtained using either the cis- or trans-monomer. Positive assignment of the stereochemistry has yet to be made, and a similar situation occurs for poly(methy1 propenyl ether).' 7 0 The polymer-ization of a number of vinyl ethers of oxy-acenaphthenes (38; R' = R2 = OCH=CH,; R' = H R2 = OCH=CH,; R' = OH R2 = OCH=CH,) has been reported.' " These monomers are cationically polymerizable by BF, etherate and are also susceptible to radical polymerization.Episulphides and epoxides although structurally similar show important differences in mode of reaction in ring-opening polymerization.' 72 cis and trans-but-2-ene serve as examples. Whereas the cis-sulphide gives crystalline polymer and the cis-oxide gives amorphous polymer the trans-oxide gives a crystalline polymer and the trans-sulphide does not. The difference in behaviour of the trans-compounds is ascribed to the extra length of the C-S bond which lowers steric hindrance so reducing isomer selection.The difference in the cis-compounds is suggested as resulting from co-ordination of the gegen-ion with the sulphur atom in the last-added unit. Polymerization of propene sulphide initiated by AlEt,-H,O gives amorphous polymer but addition of alcohols to the initiator system induces partial crystallinity.' 7 3 Olefin oxides may also be polymerized with dialkylzinc-tertiary alcohols' 74 or diethylzinc-nitromethane. 75 The latter system requires heat treatment at 100 "C for activation but is consequently 1 6 8 1 6 9 I 7 0 1 7 1 1 7 2 1 7 3 1 7 4 1 7 5 J. J. Harris and S. C. Temin J . Polymer Sci. Part A-1 Polymer Chem. 1972 10 1165. T. Higashimura and M. Hoshino J . Polymer Sci. Part A-1 Polymer Chem.1972, 10 673. T. Higashimura and M. Hoshino J . Polymer Sci. Part B Polymer Letters 1972 10, 269. A. I. Levchenko T. N. Pliev N. I . Shishkina and S. V. Timoshenko Polymer Sci. ( U . S . S . R . ) 1971 13 2560. E. J. Vandenberg J . Polymer Sci Part A-1 Polymer Chem. 1972 10 329. P. Dumas N . Spassky and P. Sigwalt Makromol. Chem. 1972 156 65. M. Nakaniwa I . Kameoka R. Hirai and J. Furukawa Makromol. Chem. 1972, 155 197. M. Nakaniwa I. Kameoka K. Ozaki N. Kawabata and J. Furukawa Makromof. Chem. 1972 155 185 158 P. Hyde and A . Ledwith stable and shows high catalytic activity. The nature of the catalyst is not known precisely but it is not the product of reaction of diethylzinc and nitromethane (zinc methazonate) which is inactive in polymerization.Two independent studies' 76,1 7 7 of the ring-opening polymerization of the bicyclic ether 2-methyl-7-oxabicyclo[2,2,l]heptane (39) have concluded that propagation proceeds oiu nucleophilic monomer attack at C-4 of the derived oxonium ion for both endo- and exo-isomers resulting in single (but different) stereochemistry for the polymer from each isomer (Scheme 14). The polymer H Me = 03 H + + 5 0 exo (41) Scheme 14 from the endo-isomer is thought to exist in the equatorial conformation (40), whereas the polymer from the exo-isomer has an equilibrium between the equatorial (41) and axial (42) conformations. Kinetic studies on these system^'^^,'^^ indicate that k for the endo-isomer is always larger than k for the exo-isomer. Arrhenius plots show that this difference arises chiefly from the value of the A-factor:exo AE,* 15 kcal mol-' A,* 41 x lo9 1 mol- ' s-' ; endo, AE,* 14 kcal mol-' A,* 7 x lo9 1 mol- s- '.Ring-opening polymerization studies have also been performed for oxepan (AEp * 18 kcal mol- ' A * 1.9 x lo9 1 mol- ' s- 2-methyl-2-0xazoline,'~~ and a series of gern-dichloro-bicyclo-[n,l,O]alkane~,'~~ where opening of the ring bridge is accompanied by a simul-1 7 6 J. Kops and H. Spanggard Makromol. Chem. 1972 151 21. 17' T. Saegusa M. Motoi S. Matsumoto and H. Fujii Macromolecules 1972 5 233. 1 7 8 T. Saegusa S. Matsumoto M. Motoi and H. Fujii Mucromolecules 1972 5 236. T. Saegusa M. Motoi S. Matsumoto and H. Fujii Macromolecules 1972 5 815. T. Saegusa T. Shiota S. Matsumoto and H. Fujii Macromolecules 1972 5 34.T. Saegusa H. Ikeda and H. Fujii Mucromolecules 1972 5 359. l s 2 Chr. P. Pinazzi A. Pleurdeau J. C. Brosse and J. Brossas Mukromol. Chem. 1972, 156 173 Kinetics and Mechanism of Addition Polymerization 159 taneous dehydrochlorination. Ring-opening polymerization of 3,3-dimethyl-selenetan (43) proceeds to give polymers with selenium in the main chain but only of low molecular weight due to transfer reactions to p01ymer.l~~ Anionic polymerization however gives high-molecular-weight material. The polymerization of indene (44) by methyl ethyl ketone peroxide in liquid SO has some of the characteristics of a cationic polymerization,' 84 suggested as arising from a charge-transfer interaction between an indene-SO complex and MEK peroxide but the mechanism needs further clarification.The polymer-ization of styrene initiated by metal halides and chlorosilanes is suggested as being initiated by a siliconium cation arising from charge-transfer interaction with the metal halide^.'^ Cationic polymerization of fluoral yields polymers which are thermally unstable;' 86 end-capping with a variety of reagents improves the thermal stability and allows calculations of wn by i.r. estimation of end groups. Copolymerization.-The effect of diols and triols as co-catalysts in the copolymer-ization of THF and propene oxide has been extensively studied.' 87-1 89 Although the SbC15-propane-l,2-diol system cannot initiate homopolymerization of THF, it will initiate ethylene oxide homopolymerization and copolymerization with THF.The copolymer reactivity ratios are r l (propene oxide) 1.15 and r (THF) 0.7 suggesting that THF reacts to some extent with its own active centre. Chain transfer is extensive in this system and keeps molecular weights very low. Varia-tion of diol type and concentration affects the rate of monomer consumption, explained in terms of the solvation properties of the alcohols. A study of the cationic copolymerization of anethole [ l-methyl-2-(4-methoxy-phenyl)ethylene]'90 has shown that in additions to growing cations with little 1 8 3 184 1 8 5 1 8 6 1 8 7 I 8 8 189 190 E. J. Goethals E. Schacht and D. Tack J . Polymer Sci. Part A - I Polymer Chem., 1972 10 533. A. De Souza Gomes 0. Do Conto Filho J . Polymer Sci. Part B Polymer Letters, 1972 10 725.Y . Minoura and H. Toshima J . Polymer Sci. Part A-1 Polymer Chem. 1972 10, 1109. W. K. Busfield and I. J. McEwen European Polymer J. 1972 8 789. L. P. Blanchard S. Kondo J. Moinard J. F. Pierson and F. Tahiani J . Polymer Sci., Part A - I Polymer Chem. 1972 10 399. E. J. Alvarez V. Hornof and L. P. Blanchard J . Polymer Sci. Part A- I Polymer Chem., 1972 10 1895. E. J. Alvarez V. Hornof and L. P. Blanchard J . Polymer Sci. Part A-1 Polymer Chem., 1972 10,2237. T. Higashimura K. Kawamura and T. Masuda J . Polymer Sci. Part A-1 Polymer Chem. 1972,10,85 160 P. Hyde and A . Ledwith steric hindrance [P(STY)+ P(p-OMe-STY)'] the trans-isomer is the more reactive whereas in the mutual copolymerization of cis- and trans-anethole, where the attacking cation is always the same i.e.a P-methyl-p-methoxystyryl cation the steric effect of the methyl group makes the cis-isomer more reactive. This behaviour is in contrast to vinyl ethers where the cis-isomer is always the more reactive. The copolymerization of 1,3-dioxolan with diketen is found to procede 70-80 % by addition of the dioxolan cation to the C=C bond of the diketen,'" and polymers have random arrangements of the monomer units. The copolymer-izations of dioxolan with t e t r ~ x a n ' ~ ~ (which is complicated by the high reactivity and consequent early consumption of tetroxan) and with t r i ~ x a n ' ~ ~ have also been described. Cyclopolymerization is most commonly observed in free-radical or conden-sation systems.' 94 Of interest therefore is the cationic copolymerization of benzaldehyde and divinyl ether to yield polymers with large numbers of the ring structures (45) and (46).'95 \ O-CH-I Ph 4 Polymerization by Co-ordination Catalysts Because of difficulties concerning the nature and number of active sites studies of Ziegler-Natta and related polymerizations place the emphasis on the type of catalyst used and its effect on the stereochemistry of the resulting polymer, rather than on the kinetics of the polymerization process.However a general kinetic scheme has been suggested for Ziegler-Natta polymerization occurring between adsorbed monomer and an active centre formed by reaction of a metal alkyl and a transition-metal halide,lg6 and has been shown to be valid for the system 4-methylpent-l-ene-VCl,-A1R3 .lg7 AEG is found to vary between 16.6 kcal mol- ' (benzene) and 13.7 kcal mol- ' (heptane; a poorer solvent than benzene).Determination of the number of active centres using tritiated quenchers ''I M. Okada Y. Yokoyama and H. Sumitomo Makromol. Chem. 1972 162 31. 19' Y. Yamashita T. Inoue G. Hattori and K. Ito Makromol. Chem. 1972 151 91. 1 9 3 D. Fleischer R. C. Schulz and B. Turcsanyi Makromol. Chem. 1972 152 305. For a recent review see G. C. Corfield Chem. SOC. Rev. 1972 1 523. ''' C. Aso and S. Tagami J. Polymer Sci. Part A - I Polymer Chem. 1972 10 1851. l g 6 D. R. Burfield I. D. McKenzie and P. J. T. Tait Polymer 1972 13 302. l g 7 I. D. McKenzie P. J. T. Tait and D. R. Burfield Polymer 1972 13 307 Kinetics and Mechanism of Addition Polymerization 161 gives a value of 2.3-6.1 x mol per mol VC1 chain-transfer constants for a number of aluminium alkylslg9 and monomers2oo have been estimated.Catalyst systems based on TiC1 are the most commonly studied and reports have been published concerning the polymerizations of heptenes and 0ct-2-ene,~” butadiene and ethylene,202 pr~pene,~’ and butene and substituted ethylenes.’04 The effect of hydrogen on the polymerization of 4-methylpent-1-ene catalysed by y-TiCl,-AlEt,Cl is to increase the rate of polymerization and decrease the rate of deactivation of the cataly~t.~” It is suggested that hydrogen prevents the occurrence of catalyst deactivation from monomer-polymer complexing by reacting to give (47) (Scheme 15). In the hydrogen-containing system the catalyst (47) catalytically active 0 = vacancy Scheme 15 is deactivated slowly possibly owing to the radical-forming reaction shown.The copolymerization behaviour of 4-methylpent-1-ene with STY raises certain problems.206 Copolymer analysis gives rlr2 x 4 indicating a tendency for blocking but i.r. spectra indicate a more random arrangement of monomer units since r1r2 determined by this method is approximately unity. The discrepancy is tentatively suggested as arising from the sites on the catalyst [TiCl,-Al(Bu’),] having different reactivities towards the monomers implying that overall copolymer composition is but an average of the various processes occurring. Soluble titanium catalysts of the type (n-C,H5)2Ti(R1)Cl-AlR2C12 are found to produce low-dispersion p~lyethylene.~” One polymer molecule is formed per 1 9 * D.R. Burfield and P. J. T. Tait Polymer 1972 13 315. 199 D. R. Burfield P. J. T. Tait and I. D. McKenzie Polymer 1972 13 321. 2 o o I. D. McKenzie and P. J. T. Tait Polymer 1972 13 510. 2 0 1 T. Otsu H. Nagahama and E. Endo J . Polymer Sci. Part B Polymer Letters 1972, 10 601. 2 0 2 V. A. Khodzhemirov V. Ye. Ostrovskii Ye. V. Zabolotskaya A. Ya. Gantmakher, and S. S. Medvedev Polymer Sci. (U.S.S.R.) 1971 13 2079. ’03 J. Mejzlik S . Petfik and B. Kokta Coll. Czech. Chem. Comm. 1972 37 2920. 2 0 4 K. A. Jung and H. Schnecko Makromol. Chem. 1972 154 227. 20s E. M. J. Pijpers and B. C. Roest European Polymer J . 1972 8 1 15 1 . * 0 6 Yu. V. Kissin Yu. Ya. Goldfarb B. A. Krentsel and H. Uyliem European Polymer J ., ’07 J. A. Waters and G. A. Mortimer J . Polymer Sci. Part A-I Polymer Chem. 1972, 1972 8 487. 10 895 162 P . Hyde and A . Ledwith titanium atom and the system is free of transfer reactions. When R’ is methyl or phenyl first insertion of ethylene is difficult but subsequent polymerization is similar to the case of R’ = ethyl or higher alkyl.’’* More complex titanium catalysts are used in the ring-opening polymerization of methylenecyclobutane~09 and ring-opening studies on cyclo-olefins have also been carried out using n-allylic transition-metal catalysts’ ’ ’ and more conventional Ziegler cata-lysts.” l a b ~ c Soluble vanadium catalysts”’ are able to polymerize ethylene in homogeneous solution at 120 “C. Addition of halogenated promoters reactivates catalytic sites giving polymer-chain vanadium-atom ratios greater than 250 and the system produces low-dispersion polymer (MJM, - 2).A study of the copolymerization of ethylene and propene catalysed by vanadium compounds has confirmed that the propene inserts into the metal-carbon bond via a ‘secondary’ insertion i.e. with the methyl-substituted carbon bonding to the metal (Scheme 16).’13 Me Me Me I I AH=CH2 M-CH -CH2 -CH -CH2- ___* Me Me Me I I I M-CH-CH2-CH-CH2 -CH-CH2-Scheme 16 Soluble catalyst systems based on VOCl are efficient in ethylene-propene copolymerization yielding more than one polymer chain per active site.214 The polymerization of polar monomers with this system shows quite complex behaviour ; polymerization of vinyl chloride in the presence of complexing agents” seems to occur via a co-ordination mechanism whereas MMA polymer-ization and copolymerization with STY proceeds via a radical mechanism.’ l 6 Dienes are readily polymerized by a variety of co-ordination catalysts.Buta-diene is polymerized by a ternary nickel system,2’7-219 by nickel perfluoro-2 0 8 J. A. Waters and G . A. Mortimer J . Polymer Sci. Part A-I Polymer Chem. 1972, 209 R. Rossi P. Diversi and L. Porri Macromolecules 1972 5 247. 10 1827. l o V. A. Kormer I. A. Poletayeva and T. L. Yufa J . Polymer Sci. Part A- I Polymer Chem. 1972 10 251. 2 1 1 ( a ) G . Dall’asta G . Motroni and L. Motta J . Polymer Sci. Part A - I Polymer Chem., 1972 10 1601; (6) G. Dall’asta Makromol. Chem. 1972 154 1; ( c ) E. A. Ofstead and N.Calderon Makromol. Chem. 1972 154 21. A. Zambelli C. Tosi and C. Sacchi Macromolecules 1972,5 649. l 4 G . I. Keim D. L. Christman L. R. Kangas and S. K. Keahey Macromolecules 1972, 5 217. A. Akimoto and T. Yoshida J . Polymer Sci. Part A - I Polymer Chem. 1972 10 993. ’12 D. L. Christman J . Polymer Sci. Part A - I Polymer Chem. 1972 10,471. 2 1 6 A. Akimoto J . Polymer Sci. Part A - I Polymer Chem. 1972 10 31 13. 2 1 7 A. TkaE and A. StaSko CON. Czech. Chem. Comm. 1972,37 573. 2 1 8 A. TkaE and A. StaSko Coll. Czech. Chem. Comm. 1972,37 1006. ’19 R. Pfikryl A. TkaE and A. StaSko Coll. Czech. Chem. Comm. 1972 37 1295 Kinetics and Mechanism of Addition Polymerization 163 carboxylates,220a and other complex nickel systems220b to give high cis-1,4-polymers by cobalt complexes,22' and by rhodium trichloride in emulsion or rhodium complexes in solution.222 In this latter case propagation is envisaged as occurring through a n-ally1 intermediate.Butadiene polymerization catalysed by various n-allylnickel complexes gives principally cis- 1,4-polymers although certain combinations of allylic substituents and solvents increase the trans-l,4 content.223 Studies of the polymerization of butadiene by n-crotylnickel iodide ~ a t a l y s i s ~ ~ ~ * ~ ~ ~ show that the monomer order is unity at low concentrations but decreases to 0.5 or lower at high concentrations. It is thought that (48) is the effective initiator species (Scheme 17). Me Me Me I CH I I CH I CH y.- \ / ~ *'/ CH2 I CH2 / I A,- / \ -\,\ 2C,H A' HC ( Ni Ni CH HC Ni.(48) Scheme 17 /CH2-cH2 I CH CH 'CH I Binodal molecular-weight distributions observed in this system are explained in terms of the three polymer types which may occur (i) growing chains which have not transferred (ii) dead chains and (iii) reactivated chains. This is analogous to the behaviour of free-radical polymerization before the equilibrium molecular weight is reached (less than 0.1 s) but occurs over a much larger time scale. Rhodium catalysts for the polymerization of ~ e n t a - l 3 - d i e n e ~ ~ ~ and propa-diene227 have been described. New catalysts based on Cr(OBu') are found to 2 2 0 2 2 1 2 2 2 2 2 3 2 2 4 2 2 5 2 2 6 2 2 7 ( a ) F. Dawans J. P. Durand and P. Teyssie J . Polymer Sci. Part B Polymer Letters, 1972 10 493; (b) C.Dixon E. W. Duck and D. K. Jenkins European Polymer J . , 1972 8 13. S. S. Medvedev L. A. Volkov V. S. Byrikhin and G. V. Timofeyeva Polymer Sci. (U.S.S.R.) 1971 13 1561. J. Zachoval F. Mikeg J. Kfepelka 0. Prouzova and 0. Pfadova European Polymer J., 1972 8 397. P. Bourdauducq and F. Dawans J . Polymer Sci. Part A-I Polymer Chem. 1972 10, 2527. J. F. Harrod and L. R. Wallace Macromolecules 1972,5,682. J. F. Harrod and L. R. Wallace Macromolecules 1972 5 685. J. Zachoval J. Kfepelka and M. Klimova CON. Czech. Chem. Comm. 1972,37 3271. J. P. Scholten and H. J. van der Ploeg J . Polymer Sci. Part A - I Polymer Chem., 1972 10 3067 164 P . Hyde and A . Ledwith give highly alternating copolymers of isoprene and butadiene with acrylonitrile?28 Systems producing alternating butadiene-propene 29*2 30 and butadiene-ethylene copolymers23 ' have also been reported.Various initiator systems are able to induce the copolymerization of CO with ethylene and vinyl monomers.232 The use of diethylzinc-water for the copolymer-ization of CO and propene oxide results in the formation of the polycarbonates (49) (Scheme 18). **-ZnOR + CO - .*.ZnOCO,R Me Me ZnOC0,R + CH-CH2 --+ Zn-0-CH-CH,-CO,R I I '0' (49) Scheme 18 AlEt,-CuC1,-CCl will polymerize vinyl chloride (VC) to a polymer containing nearly equal amounts of isotactic and syndiotactic Copolymerization of vinyl chloride and CO with this system gives a polymer richer in CO than that produced by conventional radical catalysts [rl(VC) 0.4; r 0.011 and a co-ordinated radical mechanism is suggested (Scheme 19).c=o Scheme 19 The activity of bis(triphenylsily1) chromate in ethylene polymerization is markedly increased by deposition on a silica-alumina support.23 Addition of aluminium alkyls further increases the activity. The active site is thought to be a chromium alkyl bound to the support polymerization occurring by insertion into the chromium-carbon bond. Chromocene is similarly activated by 2 2 8 Y. Koma K. Iimura and M. Takeda. J. Polymer Sci. Part A-1 Polymer Chem., 2 2 9 J. Furukawa and R. Hirai J. Polymer Sci. Part A-I Polymer Chem. 1972 10 2139. 230 J. Furukawa H. Amano and R. Hirai J. Polymer Sci. Part A-1 Polymer Chem., 2 3 1 J. Furukawa and R. Hirai J. Polymer Sci. Part A - I Polymer Chem.1972,10 3027. 232 H. Hoyer and H.-G. Fltzky Makromol. Chem. 1972 161 49. 233 S. Inoue M. Kobayashi H. Koinuma and T. Tsuruta Makromol. Chem 1972 155, 234 W. Kawai and T. Ichihashi J. Polymer Sci. Part A-1 Polymer Chem. 1972 10 1709. 235 W. L. Carrick R. J. Turbett F. J. Karol G. L. Karapinka A. S. Fox and R. N. 23b F. J. Karol G. L. Karapinka C. Wu A. W. Dow R. N. Johnson and W. L. Carrick, 1972 10 2983. 1972 10 68 1. 61. Johnson J. Polymer Sci. Part A - I Polymer Chem. 1972 10 2609. J. Polymer Sci. Part A-I Polymer Chem. 1972 10 2621 Kinetics and Mechanism of Addition Polymerization 165 and produces low-dispersion polyethylene. Copolymerizations using this catalyst system gives a high value of 72 for the ethylene propene reactivity ratio. Many transition-metal catalysts are available for stereoselective polymeriza-tion i.e.the preferential polymerization of one of the enantiomers in a racemic monomer. The extent to which stereoselection proceeds depends on both catalyst and monomer. A zinc-based catalyst system is able to produce monomers of up to 90% optical purity from racemic propene s ~ l p h i d e . ~ ~ ’ TiCl systems have been used in the polymerization of racemic 2-olefins. but neither these nor catalysts based on bis-[(S)-2-methylbutyl]zinc gave a degree of stereoselectivi t y greater than 5 Radiation-induced Polymerization A kinetic scheme has been proposed which takes into account the contributions from free-radical cation-radical and cationic species in 11-ray-induced polymer-i ~ a t i o n . ~ ~ ~ Application of this scheme to STY p~lymerization~~’ meets with success in explaining both the variation in rates and the molecular-weight distribu-tion observed to be dependent on the purity (wetness) of the monomer.Polymeri-zation of styrene in the solid phase proceeds to give a polymer with (basically) a binodal molecular-weight distribution whose exact form depends on the degree of post-polymerization allowed.241 From a comparison with the solution behaviour of STY parallel radical and cationic mechanisms are suggested. E.s.r. n.m.r. and thermal analysis techniques have been applied to the solid-state polymerization of acrylamideZ4’ and acrylic The activation energies of propagation are found to be 19 & 1 and 18.6 & 2 kcal mo1- ’ respec-tively and other parameters (local radical concentration radical decay with tem-perature annealing) are very similar for the two monomers.Post-polymerization of crystalline methacrylic acid gives a narrow molecular-weight distribution atactic polymer suggesting that chain-transfer reactions are unimportant.244 y-Radiation-initiated emulsion polymerization is more efficient for n-butyl acrylate than MMA.245 Polymerization of the former proceeds with an overall activation energy near zero whereas MMA has AE& z-5 kcal mol- ; results are in agreement with those from conventionally initiated systems. The polymerization of ethyl methacrylate has been studied by a calorimetric method.246 Scavenging 2 3 7 M. Sepulchre N. Spassky and P. Sigwalt Macromolecules 1972 5 92. 238 C. Carlini H.Bano and E. Chiellini J . Polymer Sci. Part A - I Polymer Chem. 1972, 239 J . F. Westlake and R. Y. Huang J . Polymer Sci. Part A - I Polymer Chem. 1972, 240 J . F. Westlake and R. Y. Huang J . Polymer Sci. Part A - I Polymer Chem. 1972, 24’ J. F. Westlake and R. Y. Huang J. Polymer Sci. Part A - I Polymer Chem. 1972, 242 C . Chachaty and A. Forchioni J . Polymer Sci. Part A - I Polymer Chem. 1972, 243 A. Forchioni and C. Chachaty J. Polymer Sci. Part A - I Polymer Chem. 1972, 2 4 4 J. B. Lando and J. Semen J. Polymer Sci. Part A-1 Polymer Chem. 1972 10 3003. 2 4 5 T. O’Neill and J. Hoigne J. Polymer Sci. Part A - I Polymer Chem. 1972 10 581. 246 L. Busulini S. Lora G. Palma and G. Lunardon European Polymer J. 1972 8 465. 10 2803. 10 1429. 10 1443. 10 2149.10 1905. 10 1923 I66 P . Hyde and A . Ledwith experiments with DPPH lead to a value of 3.2 x 1* mol* s% for k#:) and propagation rate constants are similar to those for MMA. Polymerization of barium methacrylate proceeds efficiently only if the monohydrate form is used ;247 e.s.r. spectra indicate that at least 75% of the initiating radicals are formed by addition of a hydrogen atom from the water of crystallization to the C=C bond. Analysis of kinetic curves for the polymerization of ethylene in various volumes of t-butyl alcohol-water shows that the rate is proportional to the first power of the fugacity of the monomer indicating that propagation occurs via addition of monomeric ethylene to the growing chain and not excited dimer as previously s~ggested.’~~ Termination is principally a first-order process second-order termination by radical combination only occurring at high volumes of butanol.Activation volumes of the elementary reactions occurring in this system have been obtained from pressure studies249 and give the high value of - 75 ml mol- ’ for the second-order termination reaction. If ethanol is used instead of t-butyl alcohol, chain transfer is found to occur and the first-order termination rate constant increases.’ O Radiation-induced copolymerization of tetrafluoroethylene (TFE) with vinyl ethers yields alternating copolymers over a wide range of feed comp~sition.~~’ Reactivity ratios determined for the TFE (monomer 1)-n-butyl vinyl ether system are r l 0.005 r 2 0.0015 indicative of the high degree of alternation.Solid maleimide produces crystalline polymers with U.V. irradiation but only amorphous polymers result from y-irradiation 2 5 2 copolymerizations with succinimide and maleic anhydride are also described. Copolymerization of trioxan and dioxolan can be initiated by conventional cationic mechanisms ;lg3 solid-state y-ray-initiated cationic copolymerization of these monomers gives polymers of high thermal stability.253 N.m.r. g.l.c. and thermal studies on this system show that the dioxolan is rapidly consumed resulting in a heterogeneous distribution of ethylene oxide units in the chains.254 6 Grafting Reactions Grafting of branches on to polymers which are chemically inactive is easily accomplished by y-irradiation techniques. The grafting of styrene on to poly-2 4 7 M.J. Bowden J. H. O’Donnell and R. D. Sothman Macromolecules 1972 5 269. 2 4 8 T. Wada T. Watanabe and M. Takehisa J . Polymer Sci. Part A-1 Polymer Chem., 1972 10 1655. 249 T. Wada T. Watanabe and M. Takehisa J . Polymer Sci. Part A-1 Polymer Chem., 1972 10 2639. 2 5 0 T. Wada T. Watanabe and M. Takehisa J . Polymer Sci. Part A-1 Polymer Chem., 1972 10 3039. 2 5 1 T. Hikita Y . Tabata K. Oshima and K. Ishiguri J . Polymer Sci. Part A- 1 Polymer Chem. 1972 10 2941. 2 5 2 K. Hayakawa H. Yamakita and K. Kawase J . Polymer Sci. Part A-1 Polymer Chem. 1972 10 1363. 253 I. Ishigaki A. Ito and K. Hayashi J . Polymer Sci. Part A-1 Polymer Chem. 1972, 10 751. 2 5 4 I. Ishigaki A. Ito T. Iwai and K. Hayashi J . Polymer Sci. Part A-1 Polymer Chem., 1972 10 1883 Kinetics and Mechanism of Addition Polymerization 167 ethylene255.256 and cellulose derivative^,"^ acrylonitrile on to p~lyethylene,'~~ and acrylic acid on to radiation-peroxidized propylenezS9 and on to nyl0n-6~~' serve as examples.Chemical methods of grafting are also used for suitable polymers. Several mechanisms are available according to the nature of the polymer and monomer(s) to be added. Anionic grafting of STY and butadiene on to ethylene-propene copolymers,261 cationic grafting of butadiene or isobutene on to PVC,262 and various free-radical grafting h ave been reported. Graft co-polymers with cellulose are of particular interest with respect to the modification of fibre properties. Grafting of methacrylonitrile is very efficient266 and is thought to be aided by monomer-cellulose complex formation.Branches formed of alternating STY-acrylonitrile units can be grafted on to cellulose without the necessity for a metal halide to be present to induce alternati~n,'~~ a factor again attributable to cellulose-monomer interactions. Grafting of short, alternating STY-maleic anhydride chains on to the existing branch points of polyethylene has been described.268 "' I. Kamel S. Machi and J. Silverman J. Polymer Sci. Part A-1 Polymer Chem., 2 5 6 T. Yasukawa T. Takahashi K. Murakami K. Araki T. Sasaga and H. Ohmichi, 2 5 7 J. T. Guthrie M. B. Huglin and G. 0. Phillips European Polymer J. 1972 8 747. 1972 10 1019. J . Polymer Sci. Part A-1 Polymer Chem. 1972 10 259. A. Chapiro A.-M. Jendrychowska-Bonamour and J. P. Leca European Polymer J., 1972 8 1301. 2 5 9 T. O'Neill J . Polymer Sci. Part A-1 Polymer Chem. 1972 10 569. 2 6 0 M. B. Huglin and B. L. Johnson European Polymer J. 1972 8 911. '" A. J. Amass E. W. Duck J. R. Hawkins and J. M. Locke European Polymer J. 1972, 2 6 2 N. G. Thame R. D. Lungberg and J. P. Kennedy J. Polymer Sci. Part A-1 Polymer 263 H. Jabloner and R. H. Mumma J. Polymer Sci. Part A-1 Polymer Chem. 1972 10, 2 6 4 R. N. Mukherjea and S . Sanyal J. Polymer Sci. Part B Polymer Letters 1972 10, 2 6 5 Y. Ogiwara K. Igeta and H. Kubota J. Polymer Sci. Part A-I Polymer Chem., 8 781. Chem. 1972 10 2507. 763. 1553. 1972 10 645. 2 6 6 N. G. Gaylord and L. C. Anand J. Polymer Sci. Part B Polymer Letters 1972 10, 2 6 7 N. G. Gaylord and L. C. Anand J. Polymer Sci. Part B Polymer Letters 1972 10, 285. 305. '" N. G. Gaylord A. Takahashi S. Kikuchi and R. A. Guzzi J. Polymer Sci. Part B, Polymer Letters 1972 10 95

ISSN:0069-3022    

DOI:10.1039/GR9726900133

出版商:RSC    

年代:1972

数据来源: RSC

摘要:

PART ll INORGANIC CHEMISTR 7 Introduction By D. W. A. SHARP Department of Chemistry University of Glasgow Glasgow G 12 800 The general form of the 1972 Annual Reports (Vol. 69) on Inorganic Chemistry is essentially the same as that of Volume 68. With the still increasing literature on inorganic chemistry reviewers have had to be rather more selective in their coverage of the subject this year but it is hoped that most of the major develop-ments have been recorded ; reviews take account of the Specialist Periodical Reports which should provide comprehensive cover of particular aspects. Amongst the mass of significant developments most interesting are the charac-terization of germanium and tin carbonyls (p. 225 ref. 71) by matrix techniques and of Pd(CO) and Pt(CO) (p.327 ref. 89). The preparation of hexamethyl-tungsten (p. 344 ref. 205) and the full characterization of species CrR (p. 343, refs. 197 198 201) completely support the view that transition metal-carbon bonds are normal. Probably the most interesting and useful new journal to inorganic chemists which has appeared recently is Synthesis in Inorganic and Metal-Organic Chemistry to which several references will be found in subsequent pages. The new volume of Inorganic Syntheses contains many recipes for the preparation of transition-metal (many Werner type) complexes main-group element compounds and low oxidation-state transition-metal complexes of e.g. phosphines. New volumes of Gmelin include coverage of carbon (system number 14) tin (46) lead (47) niobium (49) iron (59) silver (61) and the transuranium elements (71).The new pattern of Chemical Society review publications involves Chemical Society Reviews and significant reviews published in this journal are referred to below. The M.T.P. International Review of Science-Inorganic Chemistry-Series 1-provides a comprehensive background to many areas of inorganic chemistry. Amongst the new general reviews and articles on inorganic chemistry published during the year should be mentioned the following considerations of more theoretical aspects of the subject ; the Tilden Lecture on valence in transition-metal complexes ;2 discussions of electron-counting in cluster species ;3 the geometry of AH species ; and the persistence of atomic orbitals in compound^.^ ' F. A. Cotton (Editor) Inorg.Synth. 1972 XIII. ' K. Wade Inorg. Nuclear Chem. Letters 1972 8 559 563 823. R. Mason Chem. SOC. Rev. 1972 1 431. W. A. Lathan W. J. Hehre L. A. Curtiss and J. A. Pople J. Arner. Chem. SOC. 1971, 93 6377. C. J. Jrargensen Accounts Chem. Res. 1971,4 307. 17 172 D. W. A . Sharp On the thermodynamic side the thermochemistry of the chemical bond6 and the critical constants of inorganic substances7 have been considered. Physical techniques reviewed include metal isotope effects on vibrational spectra,* the vibrational spectra of intra- inter- and semi-metal bondsg and of solids." Aspects of ligand-field spectroscopy leading to information on the weak interac-tions between polyhedra in crystals have also been covered. The general theory of the magnetic susceptibilities and exchange coupling of cluster compounds12, and chemical applications of photoelectron spectroscopy l 3 ESCA l 4 and X-ray spectroscopy,' magnetic resonance techniques for the study of solid-state compounds,'6 and the electronic states of transition-metal complexes have been surveyed as have the use of conductivity measurements for characterisation of co-ordination compounds," co-ordination numbers of metal ions in solution ' and the kinetics of water exchange between solvent and co-ordination sphere in aquated transition-metal ions.20 Specific reviews have appeared on discharge techniques,2 photochemical reactions of solid-state transition-metal compounds,23 catalysis by metallo-enzyme~,~~ the relation between the 16- and 18-electron rules and catalytic behaviour and organometallic compound f o r m a t i ~ n ~ ~ the gauche effect,26 isomerism in metal P-diketonate~,~' thio-/3-diketonates,28 complexes of quadridentate Schiff's bases,29 paper chromatography of metal halide and thio-cyanate complexes,3o transition-metal hydride~,~ the crystal chemistry of decomposition of organometallics in a mass spectrometer,2 V.Gutmann and U. Mayer Structure and Bonding 1972,10 127. K. Nakamoto Angew Chem. Internat. Edn. 1972 11 666. E. Maslowsky jun. Chem. Rev. 1971,71 507. ' J. F. Mathews Chem. Rev. 1972,72 71. l o H. J. Becher Angew. Chem. Internat. Edn. 1972 11 26. l 1 D. Reinen Angew. Chem. Internat. Edn 1971 10 901. l 2 J. S. Griffith Structure and Bonding 1972 10 87; A. P. Ginsburg Inorg. Chim. Acta, l 3 A.D . Baber C. R. Brundle and M. Thompson Chem. SOC. Rev. 1972,1 355. l 4 C. Nordling Angew. Chem. Internat. Edn. 1972 11 83. l 5 A. Faessler Angew. Chem. Internat. Edn. 1972 11 34. l 6 A. Weiss Angew. Chem. Internat. Edn. 1972 11 607. '' D. R. Eaton and K. Zaw Co-ordination Chem. Rev. 1971 7 197. W. J. Geary Co-ordination Chem. Rev. 1971 7 81. l9 S. F. Lincoln Co-ordinarion Chem. Rev. 1971 6 309; J. F. Hinton and E. S. Amis, Chem. Rev. 1971 71,627. 2 o J. P. Hunt Co-ordination Chem. Rev. 1971 7 1. 2 1 J. E. Drake and N. P. C. Westwood Synth. in Inorg. and Metal-Org. Chem. 1972 2, 2 2 J. Muller Angew. Chem. Internat. Edn. 1972 11 653. 2 3 E. L. Simmons and W. W. Wendlandt Co-ordination Chem. Rev. 1971,7 11. 2 4 R. J. P. Williams Inorg. Chim. Acta Rev.1971.5 137. 2 5 C. A. Tolman Chem. SOC. Rev. 1972,1 337. 2-b S. Wolfe Accounts. Chem. Res. 1972 5 102. 2 7 J. J. Fortman Co-ordination Chem. Rev. 1971 6 331. 2 8 2 9 30 S. Przeszlakowski Chromatog. Rev. 1971 15 29. 3 1 Rev. 1971 5 45. 157. M. Cox and J. Darken Co-ordination Chem. Rev. 1971 7 29. M. Calligaris G. Nardin and L. Randaccio Co-ordination Chem. Rev. 1972,7 385. H. D . Kaesz and R. B. Saillant Chem. Rev. 1972,72 231 Introduction 173 complex carbides,32 complexes of poly(tertiary-ph~sphines),~ double a l k ~ x i d e s ~ ~ metal cluster^,^' triatomic pseudo halide^,^^ A1"-BV phase diagrams and melts,37 nitrogen fixation,38 the effect of metal complexes in cancer therapy,39 and inorganic fibres.40 Also published this year are proceedings of the 13th Co-ordination Chemistry4' and the 5th Organometallic Chemistry meetings.42 Definitive rules are now available on the nomenclature of inorganic ~hemistry:~ and the nomenclature of inorganic boron comp0unds,4~ and a suggested sym-bolism for chiral and achiral complexes has been described.45 The 1971 table of atomic weights is now available.46 Hydrogen is now recorded as 1.0079 and other changes now give potassium and zinc atomic weights of 39.098 and 65.38 respectively.32 H. Nowotny Angew. Chem. internat. Edn. 1972 11 906. 3 3 R. B. King Accounts. Chem. Res. 1972 5 177. 3 4 R. C. Mehrotra and A. Mehrotra Inorg. Chim. Acta Rev. 1971,5 127. 35 R. B. King Progr. Inorg. Chem. 1972 15 287; T. W. Thomas and A. E. Underhill, 3 6 Z. Iqbal Structure and Bonding 1972 10 25. 3' L. I. Marina Russ. Chem. Rev. 1971 608. J. Chatt and G. J. Leigh Chem. SOC. Rev. 1972 1 121. 3 9 D. R. Williams Chem. Rev. 1972 72 203. 40 G. Winter Angew. Chem. Internat. Edn. 1972 11 751. 4 1 Pure Appl. Chem. 1971,27 1 . 4 2 Pure Appl. Chem. 1972,30 335. 4 3 Pure Appl. Chem. 1971,28 1 . 44 Pure Appl. Chem. 1972,30 683. 4 s U. Thewalt K. A. Jensen and C. E. Schaffer Inorg. Chem. 1972 11 2129. 46 Pure Appl. Chem. 1972,30 639. Chem. SOC. Rev. 1972 1 99

ISSN:0069-3022    

DOI:10.1039/GR9726900169

出版商:RSC    

年代:1972

数据来源: RSC

摘要:

The Typical Elements By D. W. A. SHARP Department of Chemistry University of Gfasgow G12 800 M. G. H. WALLBRIDGE Department of Molecular Sciences University of Warwick Coventry CV4 7AL and J. H. HOLLOWAY Department of Chemistry University of Leicester Leicester LEI 7RH PART I Groups 1-111 1 Group1 Reduction of mixtures of metal oxides or fluorides (e.g. Li,O) and noble metals with very pure hydrogen gives intermetallic compounds which on heating in a high vacuum give the pure metal. By using noble metals as ‘catalysts’ Li Ca Sr, Ba Am and Cf may be obtained by hydrogen reduction.’ Two intermetallic structures of stoicheiometry A,B are now known Na,T1 has a complex arrange-ment of atoms comprising icosahedra and pentagonal prisms; there are no TI-TI contacts2 Lithium atoms produced at 1100-1300 K react with chloro-carbons to give polylithioalkanes e.g.CLi ;3a although monolithium derivatives of nitriles e.g. LiCH,CN are not formally electron-deficient compounds they are associated presumably by co-ordination from the nitrile Lithium halides associate with polymeric lithium alkyls in ethers and species such as Li,Me3Br are f~rmed.~‘ Nonafluorobicyclo[2,2,l]hept-2-en- 1-yl-lithium ( 1) and the Grignard derivative are relatively stable in diethyl ether and do not readily undergo /?-fluorine e l i m i n a t i ~ n . ~ ~ $,; F2 F (1) U. Berndt B. Erdmann and C. Keller Angew. Chem. Internut. Edn. 1972 11 515. S. Samson and D. A. Hansen A m Cryst. 1972 B28 930. ( a ) C. Chung and R. J. Lagow J.C.S. Chem. Comm. 1972 1078; ( b ) R.Das and C. A. Wilkie J . Amer. Chem. Soc. 1972 94 4555; (c) D. P. Novak and T. L. Brown ibid., p. 3793; (4 S. F. Campbell R. Stephens J. C. Tatlow and W. T. Westwood J . Fluorine Chem. 197112 1 439. 17 176 D. W. A . Sharp M . G. H . Wallbridge and J. H . Holloway Co-deposition of lithium atoms and nitrogen molecules produces species LIN, and N,Li,N,.4 A reinvestigation of the structure of lithium amide shows the crystal to have a distorted cubic close-packed arrangement of nitrogen atoms with lithium ions in the tetrahedral holes.'" Lithium dimethylamide LiNMe,, is best prepared from dimethylamine and butyl-lithium;5b it is a good reagent for introduction of the dimethylamino-group. The addition compound Li1,-3-ethylenediamine has the lithium in distorted octahedral co-ordination." A study of the effects of lithium halides on a-proton lineshapes of pyridine solutions has been interpreted in terms of such geometric models as linear Li+Cl-(py), linear Li+(H,O)(py) and tetrahedral Li+Cl-(~y)~ .5d The mechanisms of alkali-metal ion complex formation in solution have been reviewed ;6a amongst the methods used for studying alkali-metal complex formation are i.r.and n.m.r. spectroscopy (including 23Na spectroscopy)6b and the effect of alkali-metal ions on the N-C torsional barrier in amides.6' Pure lithium nitrite is prepared by interaction of lithium amide and ammonium nitrite in liquid ammonia. Amongst interesting structures of alkali-metal salts of oxyacids described recently may be mentioned KH(O,CCF,) which has a very short and apparently symmetrical hydrogen bond,8" and tetrameric trimethyl-phosphine oxide adducts of alkali-metal trimethylsilanoates which appear to have a cubane-type structure e.g.(2).8b Several apparently simple sodium salts R3Si ,0-PR, R~PO d 0 - K 4 K-0 I actually have the composition Na3M04(NaOH),-,~,5,12H,0 (M = P V or As) and contain sheets of composition Na(OH,) which have strong hydrogen bonds to the anionic groups present in the lattice.8c The 1,6dioxan (L) complexes NaC10,,3L NaBF4,3L and NaI,3L have the same structure as AgC104,3L with R. C. Spiker jun. L. Andrews and C. Trindle J. Amer. Chern. SOC. 1972 94 2401. ( a ) H. Jacobs and R. Juza Z . anorg. Chem. 1972,391 271 ; (b) S . Chan S. DiStefano, F. Fong H. Goldwhite P. Gysegen and E.Mazzola Synth. Inorg. Metal-org. Chem., 1972 2 13; (c) H. Gillier-Pandraud and S. Jamet-Delcroix Acta Cryst. 1971 B27, 2476; (d) D. W. Larsen J . Phys. Chem. 1972,76 53. ( a ) R. Winkler Structure and Bonding 1972 10 I ; (b) C. Lassigne and P. Baine J. Phys. Chem. 1971,75,3188; A. L. Van Geet J. Amer. Chem. SOC. 1972,94,5583; M. Herlem and A. I. Popov ibid. p. 1431; (c) W. Egan T. E. Bull and S. Forsen J.C.S. Chem. Comm. 1972 1099. ' P. Zecchini and C. Devin Compr. rend. 1972 274 C 524. * (a) A. L. MacDonald J. C. Speakman and D. HadZi J.C.S. Perkin 11 1972 825; (b) H. Schmidbaur and J. Adlkofer Chem. Ber. 1972 105 1956; (c) E. Tillmanns and W. H. Baur Acra Crysr. 1971 B27 2124 The Typical Elements 177 each metal ion octahedrally co-ordinated by oxygen ; the heavier alkali metals are too large to fit in this structure.' The chemistry of macrocyclic polyethers continues to be widely reported and has been reviewed,"" and a novel macro-tricyclic ligand (3) has been synthesized.lob The 2 1 complex between KNCS and 2,3 ;14,15-dibenzo-1,4,7,10,13,16,19,22-octaoxacyc1otetracosa-2,14-diene has the geometry (4) with close approach of an aromatic group to a potassium ion U Q and N-bridging thiocyanate groups.' OC The ligand dicyclohexyl- 18-crown-6 is in the cis-syn-cis-conformation in the isolated barium thiocyanate complex ; the J .C. Barnes and C. S. Duncan J.C.S. Dalton 1972 1732. l o ( a ) C. J. Pedersen and H. K. Frensdorf Angew. Chem. Internat. Edn. 1972,11 16; (6) J. Cheney J. M. Lehn J. P. Sauvage and M. E. Stubbs J.C.S.Chem. Comm. 1972, 1100; ( c ) D. E. Fenton M. Mercer N. S. Poonia and M. R. Truter ibid. p. 66; (4 N. K. Dalley D. E. Smith R. M. Izatt and J. J. Christensen ibid. p. 90; (e) R. M. Izatt, B. L. Haymore and J. J. Christensen ibid. p. 1308 ; (f) J. Cheney and J. M. Lehn ibid., p. 487; ( g ) D. J. Sam and H. E. Simmons J. Amer. Chem. SOC. 1972 94 4024; (h) F. Wudl J.C.S. Chem. Comm. 1972 1229 178 D. W. A . Sharp M . G. H . Wallbridge and J. H. Holloway nitrogen of the anions and a water molecule of hydration are co-ordinated to barium together with the six oxygens of the polyether.'Od The oxonium ion, H30+ may be complexed within a macrocyclic polyether,"' but if protons are located inside the molecular cavity they are very inactive and deprotonation is slow even in strong base.'OS It has been shown that potassium permanganate can be solubilized in benzene by use of a macrocyclic polyether thus providing a convenient and efficient oxidant.' Og A chiral ligand exhibits cation-dependent 0.r.d.curves which may be used to detect sodium in the presence of lithium or potassium. ' O h The alkali-metal methanethiolates MeSM have layer lattices the alkali-metal ions being four- (Li Na) or five- (K) co-ordinate." 2 Group11 Beryllium.-Although the structure of solid Be(BH,) is now known,"" the molecule is still of interest and there are apparently two isomers present in the vapour phase.'2b The complexes (RBeH),,L (R = Et Bus But or n-C,H ; L = NNN'N'-tetramethylethylenediamine) are all monomeric with a chelating ligand ;' 3a organoberyllium and organoberylliumhydride complexes have been reviewed.'3b At 173 K Cp,Be has one ring symmetrically n-bonded to the metal whilst the other ring is o-bonded in a 'slip' ~andwich;'~" both MeBeCp and CpBeCl appear from electron-diffraction studies to have symmetrically bonded Diarylberylliums can be formed in high yield by exchange between BeEt and triarylboranes; they form adducts with amines and ethers :' BeEt, reacts with NMe,SCN to form NMe,[(Et,Be),SCN] which is sulphur-bonded.'" Polymeric butoxyberyllium derivatives e.g. (ClBeOBu',L) (L = Et,O) and Me,Be,(OBu'), are formed from Be(OBu') and BeX ; SBu' and Me,N groups may also be substituted ;' 6a alkoxides derived from other tertiary alcohols are also polymeric.'6b The Be(NH,) - ion in KBe(NH,) is approximately planar with a relatively short Be-N bond which is consistent with some pn-pn bond-ing.' The structures of fluoroberyllates are now being determined.Salts MLiBeF (M = K NH, or Cs) have discrete BeF,'- tetrahedra"" whereas pentafluoroberyllates MBe,F (M = K NH, Rb T1 or Cs) have sheet anions, while one form of CsBe,F contains a complex arrangement of ten-membered rings of linked BeF tetrahedra.' 8b E. Weiss and U . Joergens Chem. Ber 1972 105 481. ( a ) D. W. A. Sharp M. G. H. Wallbridge and J. H. Holloway Ann. Reports 1971,68, A 256; ( 6 ) J . W. Nibier J . Amer. Chem. SOC. 1972 94 3349. l 3 ( a ) U. Blindheim G. E. Coates and R. C. Srivastava J.C.S. Dalton 1972 2302; ( 6 ) F. Bertin and G. Thomas Bull. SOC. chim. France 1971 3951.l 4 ( a ) C.-H. Wong T.-Y. Lee K.-J. Chao and S. Lee Acta Cryst. 1972 B28 1662; ( b ) D. A. Drew and A. Haaland J.C.S. Chem. Comm. 1971 1551. l 5 ( a ) G . E. Coates and R. C. Srivastava J.C.S. Dalton 1972 1541; (6) N. Atam H. Miiller and K. Dehnicke J . Organometallic Chem. 1972 37 15. ( a ) R. A. Andersen N . A. Bell and G. E. Coates J.C.S. Dalton 1972 577; ( 6 ) R . A. Andersen and G. E. Coates ibid. p. 2153. L. Guemas-Brisseau M. G . B. Drew and J. E. Goulter J.C.S. Chem. Comm. 1972, 916. ( a ) J . Le Roy and S. Aleonard Acfa Cryst. 1972 B28 1383; ( 6 ) Y . Le Fur ibid. p. 1 159; Y . Le Fur and S. Aleonard ibid. p. 21 15 The Typical Elements 1 79 Magnesium Calcium Strontium and Barium.-Both X-ray photoelectron and X-ray emission spectroscopy' may be used to determine co-ordination numbers in magnesium and aluminium compounds.Some properties of atomic magne-sium and calcium have been described Ground-state magnesium ('S) reacts with alkyl halides to give unsolvated Grignard reagents on warming; at 77K a black matrix in whch the magnesium appears to be weakly bonded to the halogen of the RX is obtained and these compounds have novel properties.20" Calcium atoms defluorinate unsaturated fluorocarbons e.g. CF3CF=CFCF, yields CF3CECCF,.20b A very active form of magnesium may be prepared by reducing the anhydrous halides with an alkali metal in an ethereal solvent.20c The existence of BaB has now been confirmed.2'" CaMgX and SrMgX (X = Si Ge Sn or Pb) have the ordered anti-PbC1 structure and are related to the binary compounds Ca,X whereas compounds BaMgX have the anti-PbFC1 structure.l b X-Ray crystallography confirms the presence of a symmetrical 7c-C5H5 group in CpMgBr,Et,N(CH,),NEt in the solid state.22 Many organomagnesium derivatives are associated in solution and two different bridges e.g. a methyl and an OCPh,Me are present in derivatives such as MeMgOCPh,Me., The action of hydrogen at high temperatures on strontium nitrides gives mixed nitride-hydrides e.g. Sr,N - .H ; these observations account for the previous records of non-stoicheiometry in these nitride^.,^" Ba,N forms a mixed silicide nitride BaSiN with Si,N .24b Calcium hydrazinecarboxylate has anions which both chelate one CaZf ion and bridge two such ions; co-ordination numbers about the metal are high zinc complexes have similar anionic arrangements but lower co-ordination numbers.Radical anions e.g. the anion of glyoxal-bis-(N-t-butylimine) form complexes with Mg2 + Ca2 + or Zn2 + which may be studied by e.s.r. spectroscopy;25b the Ca2+ ion shows a very specific interaction with the nucleoside g u a n ~ s i n e . ~ ~ ~ Magnesium p-diketonates form adducts with bidentate ligands such as o-phenanthroline and thus behave similarly to transition-metal derivative^.,'^ KHC03,MgC0,,4H20 has a very close approach of carbonate groups and thus a very short 0-He -0 hydrogen bond the magnesium atom being in octahedral co-ordination and the potassium " C. J . Nicholls D. S. Urch and A. N . L. Kay J.C.S. Chem. Comm. 1972 1198; F. Freund and M. Hamich Z . anorg. Chem. 1971,385 209.' O ( a ) P. S . Skell and J. E. Girard J . Amer. Chem. SOC. 1972,94,55 18; ( 6 ) K. J. Klabunde, J . Y . F. Low and M. S. Key J . Fluorine Chem. 197213 2 207; ( c ) R. D. Rieke and P. M. Hudnall J . Amer. Chem. SOC. 1972 94 7178. ( a ) K . Torkar H. Krischner and E. Hitsch Monatsh. 1972,103,744; ( 6 ) B. Eisenmann, H. Schafer and A. Weiss Z . anorg. Chem. 1972 391 241. 2 2 C. Johnson J . Toney and G. D. Stucky J . Organometallic Chem. 1972 40 C1 1 . 2 3 J . A. Nackashi and E. C. Ashby J . Organometallic Chem. 1972 35 C1. 2 4 ( a ) J.-P. Motte J.-F. Brice and J. Aubry Compt. rend. 1972,274 C 1814; J.-F. Brice, J.-P. Motte and J . Aubry ibid. p. 2166; ( b ) J . Gaude and J . Lang ibid. p. 521. 2 5 ( a ) A. Braibanti A. M. Manotti Lanfredi M. S. Pellinghelli and A.Tiripicchio Acra Crysr. 1971 B27 2261 2448 2453; (6) P. Clopath and A. V. Zelewsky Helv. Chim. Acra 1972,55,52; (c) F. Jordan and B. Y. McFarquhar J . Amer. Chem. SOC. 1972,94, 6557; (6) D. E. Fenton J . Chem. SOC. ( A ) 1971 3481 180 D. W. A . Sharp M . G. H . Wallbridge and J. H. Holloway twelve-co-ordinate with respect to oxygen ;26a distorted octahedral co-ordination is also found about magnesium in nesquehonite MgC0,,3H,0,26b and in the tris(hexafluoroacety1acetonato)magnesiumate of monoprotonated 1,8-bis(di-methy1amino)naphthalene [the proton lies in the plane of the naphthalene ring, between the two nitrogen atoms ; the corresponding copper salt is isomorphous with the magnesium deri~ative].~~‘ Alkoxymagnesium halides previously postulated in many reactions are polymeric e.g.3Mg(OR),,MgX2,nROH and are formed by interaction of the alkoxide and halide.27 3 Group I11 This year has seen the appearance of a book dealing with the development of the use of the boranes in organic chemistry and although it gives a personalised view it makes interesting reading.28 Another review in part by the same author deals with free-radical displacement reactions of organoboranes including the use of such reactions in organic syntheses and emphasizes the fact that organoboranes form a useful source of free radicals.2g Other reviews have dealt with recent studies on diborane,,’ the carbaboranes,,’ organometallic aspects of diboron and the co-ordination chemistry of thallium(~).~~ The general areas of the reactions of metal carbonyls with aluminium gallium and indium trialkyl~,,~ and the gaseous oxyhalides hydroxides and complex oxides of the Group I11 elements35 have also been reviewed.Boron.-The published work this year has again been dominated by interest in the boron hydrides the carbaboranes (including their metallo derivatives) and various heterocyclic derivatives containing boron. Variations in the binding energies of the boron 1s electrons in gaseous BF BCl, B(OMe) B,H, BMe , H,B,CO and H,B,NMe have been shown to be linearly related to the charges on the boron atoms as estimated from various calculations. The best correlation occurs with extended Huckel charges after the interatomic ‘Madelung potential’ has been included although the 1s binding energies do not show any obvious relationship to “B n.m.r.chemical shifts.36 Other calculations have shown that the hybrid orbital force field (HOFF) model can be successfully applied to adducts of borane (e.g. H,B,CO and H,B,NMe,) and substituted borane anions (BH,X, where X = F- CN- or NC-).37 Although a series of calculations of potential ’’ ( a ) G. W. Stephan C. H. MacGillavry and B. Koch Acta Cryst 1972 B28 1029; ( b ) G. W. Stephan and C. H. MacGillavry ibid. p. 1031 ; ( c ) M. R. Truter and B. L. Vickery J.C.S. Dalton 1972 395. N. Y. Turova and E. P. Turevskaya J . Organometallic Chem. 1972,42 9. H. C. Brown ‘Boranes in Organic Chemistry’ Cornell University Press London 1972. H. C . Brown and M. M. Midland Angew Chem. Internat. Edn. 1972 11 692. D. T. Haworth Endeavour 1972 31 16.A. G. Lee Co-ordination Chem. Rev. 1972 8 289. D. F. Shriver and A. Alick Co-ordination Chem. Rev. 1972 8 15. L. H. Ngai and F. E. Stafford Adv. High Temp. Chem. 1971 3 213. 27 2 8 2 9 3 0 L. H. Long Progr. Inorg. Chem. 1972 15 1 . ” 3 2 T. D. Coyle and J . J . Ritter Adv. Organometallic Chem. 1972 10 237. ” j 4 3 5 3 6 P. Finn and W. L. Jolly J. Amer. Chem. SOC. 1972 94 1540. 3 7 K. F. Purcell Inorg. Chem. 1972 11 891 The Typical Elements 181 surfaces for HeB' NeB' and ArB+ suggest that XeB' might be stable in reactions involving xenon and boron-fluorine compounds the B-F bond strength is sufficiently high to preclude any XeB' formation even when anions such as SbF6 - are used.3 The simple skeletal-electron-counting approach which allows the shapes of the polyhedral borane anions to be rationalized has now been extended to estimating bond orders and charge distribution in BgHg2-, B9Hg2- and BloHIo2-.Those skeletal atoms of lowest and highest co-ordination numbers are respectively negatively and positively charged relative to the other framework atoms.39 Another general treatment of the stereochemistries of polyhedral frameworks suggests that for both the boron hydrides and for carba-boranes the observed polyhedra adopt structures which contain boron atoms a vertices which are four- or five-co-ordinate while vertices of orders three or six are avoided as much as possible.40 A brief discussion of an attempted system-atization of borane and carbaborane chemistry using Huckel-type rules has also appeared.Boron Hydrides. This section deals with the boranes their derivatives and neutral complexes. The borane anions are discussed below. The chemical ionization mass spectra of B2H6 B4H10 B,H, B5Hll and B6H10 in methane have been studied. Two different modes of ionization are observed; for B,H6 B4H10 and BSH a dissociative proton transfer and hydride-abstraction processes occur to form (M - 1)' ions while for B,H and B6H10 proton transfer yields the (M + 1)+ ions. The results also suggest that the proton affinity of is greater than that of B,H, indicating that a relative order of Lewis acidity may be derived.42 Futher calculations on diborane suggest that many of its properties (ionization potentials shielding constants total electron densities etc.) may be estimated reliably from a minimum basis set using extended Slater orbital wave-functions.43 Other calculations have been concerned with the energies of forma-tion of diborane (- 79.8 kJ mol- l ) and the B2H,- ion (- 105.4 kJ mol-') using an ab initio SCF approach,44 and the electronic structure of the B2H5+ ion (ob-served for example in the mass spectrum of diborane) using a basis set of Gaussian orbitals allows the conclusion that the most stable structure is a planar unit with two vacant p-orbitals rather than a hydrogen-bridged unit related to dib~rane.~, So far as the chemical reactivity of borane (BH,) and diborane is concerned a mass spectrometric study of the rate of reaction of acetone with borane has shown the reaction to be bimolecular and while the product has a mass correspond-ing to BC3H,0 it is probably not an alkoxyborane but instead the adduct Me,C0,BH3.46 A similar study in a fast-flow system of the reaction between 3 8 J .F. Liebman and L. C. Allen Inorg. Chem. 1972 11 1143. 3 9 K. Wade Inorg. Nuclear Chem. Letters 1972 8 823. 40 R. B. King J . Amer. Chem. SOC. 1972,94 95. 4 ' R. W. Rudolph and W. R. Pretzer Inorg. Chem. 1972 11 1974. 42 J . J . Solomon and R. E. Porter J . Amer. Chem. SOC. 1972 94 1443. 4 3 E. A. Laws R. M. Stevens and W. N. Lipscomb J . Amer. Chem. SOC. 1972,94,4461. 4 4 J. H. Hall D. S. Marynick and W. N. Lipscomb Inorg. Chem. 1972 11 3126. 4 5 46 T. P. Fehlner Inorg. Chem. 1972 11 252. B. J . Duke and D. G. Stephens Theor. Chim. Acta 1972 26 381 182 D. W. A . Sharp M. G. H .Wallbridge and J. H. Holloway B,H and B5H9 indicates that the initial reaction is B5H9 + BH -+ B,H,,; the product either eliminates hydrogen to yield B6H10 or rearranges to the known hexaborane( 12) structure. Other results show that another initial reaction is B2H6 + BH + B3H9; this intermediate of diborane postulated to occur in the pyrolysis also eliminates hydrogen in forming B,H fragment^.^' Several reactions of diborane with nucleophiles have been further investigated. Thus while it is well known that asymmetric cleavage occurs with ammonia at room temperature when the reaction is carried out in n-hexane at 229K the borane adduct H,N,BH is formed in 22% yield and if diethyl ether is present the yield is increased to 45%.48 With water on the other hand when the dihydrate B2H6,2H20 is prepared at 143 K i.r.data obtained at low temperatures are consistent with the asymmetric cleavage product [BH,(H20),]+BH4-.49 The simple fluoroborane adducts F,HB,L (L = NMe or NEt,) have been prepared by a redistribution rea~tion,~'" and an attempt to determine the relative acceptor properties of F,BH and BH towards trimethylamine has been complicated by the fact that while BH displaces F,BH from F,HB,NMe the displaced borane disproportionates to BF and BH, although it was concluded that boron trifluoride is the strongest acceptor in the series BF F,BH FBH, and BH .50b In 1-methyl-2-substituted-piperidine-borane compounds the stereochemistry is influenced less by the substituent than for the 3- or 4-substituted derivatives and this has been related to the energetics of quaternary salt formation of substituted piperidine~.~'" Another general study of borane adducts [e.g.H,B,L (L = NMe, or PMe,)] has shown that the commonly observed upfield aromatic-solvent-induced shifts (ASIS) in 'H n.m.r. spectra of organic compounds can be reversed when the proton bears a partial negative charge since in C6D6 a downfield shift of the hydridic protons of the borane group occurs compared with the values in carbon tetrachloride ~olution.~ The question of whether the bis-borane compound with ethylenediamine H3B,NH2(CH,),NH,,BH3 exists in the gauche-or trans-conformation in the solid phase has been answered from an X-ray investigation which shows it to be the latter.52 Several new fluorophosphine-borane compounds have been identified including MeSPF,,BH ; MePF,,BH ;53a XF,P,BH3 (X = F C1 Br or I);53b and F,P(NMe,),-,,BH,.53' Relative base strengths have been established for some of the ligands as MePF > Me,NPF > MeOPF > MeSPF and in part this order of basicity has been correlated with .IBp from the n.m.r.spectra of the compounds. In the ligands F,P(NMe,),-, both the phosphorus (towards BH,) and nitrogen (towards BF,) can act as donor " S. A. Fridmann and T. P. Fehlner Inorg. Chem. 1972 11 936. '* E. Mayer Inorg. Chem. 1972 11 866. 4 9 P. Finn and W. L. Jolly Inorg. Chem. 1972 1 1 1941. ( a ) H. Mongeot J. Dazord and J . P. Tuchagues J . Inorg. Nuclear Chem. 1972,34,825; (6) J . M. Van Paasschen and R. A. Geanangel Inorg. Nuclear Chem. Letters 1972 8, 879.5 1 ( a ) R . E. Lyle E. W. Southwick and J. J. Kaminski J . Amer. Chem. Soc. 1972 94, 1413; (b) A. H. Cowley M. C. Damasco J. A. Mosbo and J. G. Verkade ibid. p. 671 5. 5 2 H. Ting W. H. Watson and H. C. Kelly Inorg. Chem. 1972 11 374. 5 3 ( a ) R. Foester and K. Cohn Inorg. Chem. 1972 11 2590; (b) R. T. Paine and R. W. Parry ibid. p. 1237; (c) S. Fleming and R. W. Parry ibid. p. 1 ; (d) R. T. Paine and R. W. Parry ibid. p. 210 (e) P. S. Bryan and R. L. Kuczkowski ibid. p. 553 The Typical Elements 183 atoms depending upon the boron compound that is used as the acceptor. The compound F4P2 ,2BH, which is stable at 228 K but unstable at 273 K has been prepared by a new route using BH,,CO as the source of b~rane.’,~ The predicted structures of Me P,BH and MeH,P,BH involving near tetrahedral arrange-ment around the boron atoms have been verified from microwave spectro-Bridge-substituted thio-diboranes p-RS-B,H have been obtained from the SCOpy.53e reaction scheme :’, KBH + (RSBH,), 353 K 7 KSR + B2H6 + K[RS(BH,),]/ \ Elimination of hydrogen occurs when excess diborane reacts with heptasulphur imide S,NH and the substituted borane S,NBH is obtained; further sub-stitution to (S,N),BH occurs in the presence of excess imide.”“ The reaction of diborane with lithium amides (LiNHR’ and LiNRi where R’ = Me Et, n-C,H, etc; R2 = Me Et n-C3H7 or i-C3H7) results in the formation of lithium borohydride and tris(amino)boranes while excess diborane yields several new p-amino-dib~ranes.~’~ In contrast n-butyl-lithium reacts with H,P,BH to yield Li(H,PBH,) which reacts further with diborane forming Li[H,P(BH,),].55‘ The related compound Li[Me,P(BH,),] reported last year reacts with the protonic hydrogen in alkylammonium chlorides eliminating hydrogen and form-ing compounds which contain a framework of (amine)-BH,-PMe,-BH .’ 5d When organic isocyanates RNCO (R = Me or Ph) are treated with diborane, cyclic trimers [H,B-N(R)(CHO)] are obtained ; a similar reaction occurs with MeNCS but PhNCS forms monomeric PhNCS,BH and dimeric (PhNCS,BH,), species.’‘ Derivatives of aluminium hydroborate namely Me,NAl(BH,) 7n or H,B(NMe),Al(BH,) ,’ 7 b result when the aluminium compounds Me,NAlH, and Al(NMe,) respectively are treated with diborane in ether solution at room temperature.’ Although borane carbonyl BH,,CO reacts similarly to carbon dioxide with primary and secondary amines it reacts differently with potassium glycinate in ethanol forming a 1 1 adduct K+[H,BC(0)NH,CH,COO]-.58 The molecular-beam mass spectra of Me,NPF ,B3H7 and F,P,B,H have been recorded and pyrolysis of the former compound affords a high-yield source of the B,H intermediate and Me,NPF ,B,H, which in turn yields B4H8 .59a 5 4 J.J . Mielcarek and P. C. Keller J.C.S. Chem. Comm. 1972 1090. 5 5 (a) M. H. Mendelsohnand W. L. Jolly Inorg. Chem. 1972,11 1944; (b) L. D. Schwartz and P. C. Keller J. Amer. Chem. SOC. 1972,94 301 5 ; (c) E. Mayer Inorg. Chem. 1971, 10 2259; (d) L. D. Schwartz and P. C. Keller ibid. 1972 11. 1931. 5 6 R. Molinelli S. R. Smith and J. Tanaka J.C.S. Dalton 1972 1363.5 7 ( a ) P. C. Keller Inorg. Chem. 1972 11,256; (b) P. C. Keller J. Amer. Chem. SOC. 1972, 5 8 5 9 ( a ) R. T. Paine G. Sodeck and F. E. Stafford Inorg. Chem. 1972 11 2593; (b) R. T. 94 4020. M. J. Zetlmeisl and L. J. Malone Inorg. Chem. 1972 11 1245. Paine and R . W. Parry ibid. p. 268 184 D. W. A . Sharp M. G. H . Wallbridge and J. H . Holloway The base replacement of dimethyl ether in Me,O,B,H by PF and CO is assisted by the presence of boron trifluoride to complex with the liberated ether.596 Further studies on n-borallyl species have included a crystal stucture determina-tion on (Me,PPh),Pt(B,H,) which shows the metal atom to be in an essentially square-planar environment with the B3H7 entity bonded asymmetrically to the metal but probably not involving M-H-B bonds6' Two interesting com-pounds Me,MB3H8 (M = A1 or Ga) have been prepared from the corresponding chloro-compounds Me,MCl by reaction with the B,H8- ion and while they appear to have static structures at room temperature at higher temperatures the protons in the B,H group show fluxional behaviour.61 A detailed investigation of the scrambling reactions of p-B,H,D and p-B,D9H has established that intramolecular hydrogen exchange occurs at two rates.The faster process involves the bridge and four of the terminal protons while the slower one involves the bridge and two remaining terminal protons attached to the 2,4-boron atoms. A possible pathway for such an exchange is illustrated in (5).62 I -3-OR ( 5 ) H B I ' (W H (6) 6 o L. J .Guggenberger A. R. Kane and E. L. Muetterties J . Amer. Chem. SOC. 1972,94, " 62 5665. J. Borlin and D. F. Gaines J . Amer. Chem. SOC. 1972 94 1367. R. Schaeffer and L. G. Sneddon Inorg. Chem. 1972 11 3098 The Typical Elements 185 Long-range coupling of the basal and apical protons in the 'H n.m.r. spectrum of pentaborane(9) has been detected using double-resonance technique^,^," and it has been suggested that the "B n.m.r. shifts in both pentaborane(9) and phenylboronic acid are determined by a resonance and inductive effect.63b The adduct of pentaborane(9) with ammonia has been characterized as B5H,,2NH ; it is stable below 273 K and is formulated as H,B(NH,),+ B4H,-,64a while a 1 1 adduct with trimethylamine 1-MeB5H,,NMe, is also unstable at room temperature and is suggested to possess a structure where the ligand is attached to a basal boron atom in a way which allows for tautomerism of the basal protons.64b The interaction of 1-SiH3B5Hg with boron trichloride yields the chlorosilyl compound 1-C1SiH2B,H without cleavage of the Si-B and the isomerization of 2,3-p-(phosphino)-BsH [phosphino = (CF,S)PCF Ph,P or MePCl] to the 1- or 2-derivative has been The tetrabutylammonium salts of the B,H,- and B6H9- ions have been prepared and their decomposition to yield the B,HI4- and B11H14- ions has been ~tudied.~" It has been shown that in addition to the well-known deprotonation of the boron hydrides the direct addition of a proton can be accomplished for hexaborane(l0) in the reaction with liquid hydrogen chloride (or bromide) the resulting cation being isolated as B6Hll+ BCl,- at low temperatures;66" both 'H and "B n.m.r.spectra of B6H10 at 126 K have resolved for the first time distinct bridging and terminal protons and boron atoms.66b A transition-metal derivative p-Fe(CO),-has been obtained as a volatile yellow crystalline compound from the reaction of Fe,(CO) with hexaborane( lo) the suggested structure being as shown in (6).67 The question as to whether any heptaboranes exist has been discussed and an examination of existing mass spectral data supports the existence of B,H .68a New 'H and "B n.m.r. data obtained at 220 MHz and 70.6 MHz respectively, for B8H12 B,H,, and B10H16 have been interpreted in terms of C, symmetry for the B skeleton in BgH12 and two B,H units bonded at the 2,2'-positions for BsHls while the spectra for BlOH16 are consistent with two B,H units boron-boron bonded at the 2,2'-po~itions.~~~ Few reactions of n-nonaborane( 15), B9H15 have been reported but recent studies show that cleavage reactions occur with acetonitrile to yield BgH12 ,NCMe and (-BNCMe-) whileammonia and sodium amalgam deprotonate the hydride forming the B,H 14- ion6,' " ( a ) T.Onak J . C . S . Chem. Comm. 1972,351 ; (b) A. R. Siedle and G. M. Bodner Inorg. Chem. 1972 11 3108. 6 4 ( a ) G. Kodama U. Engelhardt C. Lafrenz and R. W. Parry J . Amer. Chem. Soc., 1972 94 407; (b) G. Kodama ibid. p. 5807. '' ( a ) T. C. Geisler and A. D . Norman Inorg. Chkm. 1972 11,2549; ( b ) I . B. Mishra and A. B. Burg ibid. p. 664; (c) V. T. Brice H .D. Johnson D . L. Denton and S. G. Shore, ibid. p. 1135. '' ( a ) H. D . Johnson V. T. Brice G. L. Brubaker and S. G. Shore J . Amer. Chem. Soc., 1972,94 671 1 ; (b) V. T. Brice H. D. Johnson and S. G. Shore J.C.S. Chem. Comm., 1972 1128. " A. Davison D . D . Troficanto and S. S. Wreford J.C.S. Chem. Comm. 1972 1155. 6 8 (a) E. McLaughlin and R. W. Rozett Inorg. Chem. 1972 11 2567; (6) R . R. Rietz, R. Schaeffer and L. G. Sneddon ibid. p. 1242; (c) R. Schaeffer and L. G. Sneddon, ibid. p. 3102 186 D. W. A . Sharp M. G. H . Wallbridge and J. H. Holloway Further calculations on decaborane(l4) BioH14 have obtained an SCF wavefunction from a minimum basis set of Slater-type orbitals and good cor-relations of reactivity with electron distribution can be obtained in addition to an improved description of localized orbitals.69" The structural ambiguity which has existed for the B10H142- ion has been resolved since the "B n.m.r.spectrum (at 80.5 MHz) confirms the presence of two BH groups at the 6,9-positions,69b and the crystal structure of the BIoH13- ion at 103 K shows that the ion has a similar boron framework to B10H14 with a bridging hydrogen atom removed with the consequential decrease in the B-B separation to 165 pm. This is one of the shortest B-B distances reported since the same workers have re-examined the crystal structure of B6Hlo and found that the short B-B separation reported as 160 should be 163 pm.69c In the preparation of 5- and 6-halogeno-derivatives of decaborane B10H13X from the action of hydrogen halides on (R,S),BloHl steric effects become important in that the 6-isomer becomes less favoured as the size of the ligand and halogen in~rease.~' A novel compound in which dinitrogen bridges ruthenium and boron atoms has been identified as [(PPh,),Ru(N,)H,],B formed from the action of diazonium derivatives of EJlOHlo2- [namely Bl0H8(N2),] on (PPh,),Ru(N,)H .71a The crystal structure of the trichloro derivative of BloHlo2- in (NMe,)2B,oH7C13 shows that the B,, cage almost retains its D, symmetry with the three chlorine atoms attached to one apical boron and two opposite equatorial borons which are nearest to the other apical boron.71b Borane Anions and Cations.The rapid first step in the acid hydrolysis of the BH,-ion which yields H,O,BH when H,O+ comes into direct contact with BH,-, is apparently diffusion-controlled72" while the second intermediate (H20),BH2+ is stable towards hydrolysis at 195 K in the Hf concentration range of 0.1-1.1 mol 1-'.72b However the conjugate base of this latter species H20,BH20H [formed from the equilibrium (H,O),BH; H+ + H,O,BH,OH] hydrolyses to H,O,BH(OH) and this species at 237 K is further hydrolysed to B(OH) .The hydroborate ion has been isolated as the triamino-guanidinium salt [C(NHNH,),]-BH4 by treating the corresponding sulphate with sodium hydr~borate,~~" and a range of volatile cyanoboranes (BH2CN) (where x = 4 5 6 7 8 9 or 10) have been obtained from the action of hydrogen chloride on the BH,CN- ion.73b Several studies relate to the metal hydroborates and vibrational spectroscopy has been applied to the problem of determining whether the BH group is bonded 6 9 (a) E.A. Laws R. M. Stevens and W. N. Lipscomb J. Amer. Chem. SOC. 1972 94, 4467; (6) W. N. Lipscomb R. J. Wiersema and M. F. Hawthorne Inorg. Chem. 1972, 11 651; ( c ) L. G. Sneddon J. C. Huffman R. 0. Schaeffer and W. E. Streib J.C.S. Chem. Comm. 1972,474. ( a ) W. H. Knoth J . Amer. Chem. SOC. 1972,94 104; ( 6 ) F. E. Scarborough and W. N. Lipscomb Inorg. Chem. 1972 11 369. l 2 ( a ) L. A. Levine and M. M. Kreevoy J. Amer. Chem. SOC. 1972 94 3346; ( b ) F. T. Wang and W. L. Jolly Inorg. Chem. 1972 11 1933. 73 (a) L. V. Titov and M. D. Levicheva Russ. J. Inorg. Chem. 1972 17 334; (b) B. F. Spielvogel R. F. Bratton and C. G. Moreland J . Amer. Chem. SOC. 1972,94 8597. ' O B.Stibr J. Plesek and S. Hermanek Coll. Czech. Chem. Comm. 1972 37 2696 The Typical Elements 187 to the central metal atom by uni- bi- or ter-dentate hydrogen bridge while the temperature-dependence of the 'H n.m.r. spectra of M(BH,) (M = Zr or Hf) compounds has been ascribed to variations in the rate of the loB and "B quadrupole spin-lattice relaxation constants.74b Distinct bridging and terminal protons in the BH group can be observed in the 'H n.m.r. spectrum of ( Z - C ~ H ~ ) ~ -UBH, which has a triple hydrogen bridge bond at 153 K after broad-band decoupling of the ' 'B nucleus.75P The crystal structure of the U(BH,) compound has been determined from X-ray data and shows that the BH groups form a polymeric lattice in which they are linked by uranium atoms each metal atom being associated with six BH groups four of which form bridges with other metal atoms and two of which are terminal groups only.75b The reactions and equilibria involved in the mixtures of LiX salts (X = H D C1 or BH,) with aluminium hydroborate Al(BH,) have been further discussed.76 Fewer developments in the area of borane cations have appeared this year, apart from the + species mentioned above.Several new borane cations containing amides or cyanide substituents have been prepared by the following route :77 Me,M,BH,I + L + Me,M,BH,(L)+ I-(M = N or P; L = aliphatic primary amides aromatic secondary amides, or MeCN). Carbaboranes and Metallo-carbaboranes. The published papers in this area emphasize that both the carbaboranes and the interaction of carbaborane anions with metals continue to be of considerable interest.Perhaps the most significant developments lie in the areas concerned with the preparation of metallo-carbaboranes and the relationships between such compounds in that specific interconversions are now becoming possible either by polyhedral con-traction reactions brought about by base degradation or by thermal rearrange-ments. In a brief general paper the occurrence of fractional three-centre bonds in the carbaboranes is proposed to allow sensible single-valence structures to be drawn for C2B,H, 1,6-C2B,H6 and 2,4-C,B,H7 . 7 8 Two interesting methods for the preparation of carbaboranes have been reported ; one involves the pyrolysis of trimethylboron at - 773 K which yields B-methyl derivatives of the predicted nido-C4B6HlO carbaborane e.g.C,H,(BMe) ,79u the other is a low-temperature conversion of 2C into 4C carbaboranes as typified by the reaction 1,2-C2B3H7 + C,H -+ 2,3,4,5-C4B,H, which occurs at 323 K.79b 7 4 (a) T. J. Marks W. J. Kennally J. R. Kolb and L. A. Shimp Inorg. Chem. 1972 11, 2540; (6) T. J. Marks and L. A. Shimp J. Amer. Chem. SOC. 1972,94 1542. " (a) T. J. Marks and J . R. Kolb J.C.S. Chem. Comm. 1972 1019; (b) E. R. Bernstein, T. A. Keiderling S. J. Lippard and J. J. Mayerle J . Amer. Chem. SOC. 1972,94 2552. 7 6 N. Davies and M. G . H. Wallbridge J.C.S. Dalton 1972 1421. 7 7 D. L. Reznicek and N. E. Miller Inorg. Chem. 1972 11 858. '* D. S. Marynick and W. N. Lipscomb J. Amer. Chem. SOC. 1972 94 1748. 7 9 M. P. Brown A.K. Holliday and G. M. Way J.C.S. Chem. Comm. 1972 850; (b) V. R. Miller and R. N. Grimes Inorg. Chem. 1972 11 862 188 D. W. A . Sharp M . G. H. Wallbridge and J. H . Holloway The closo-carbaborane 1,5-C2B,H forms a 1 1 compound with trimethyl-amine at 195 K which decomposes at room temperature to form unidentified products,'0a and the 1 1 adduct between the same base and the closo-carbaborane 1,6-C2B4H undergoes a novel rearrangement to yield a zwitterion with the suggested structure (7).80b Negative-ion mass spectrometry is useful when it is applied to nido-carbaboranes since the ions obtained (e.g. CZB4H - or C,B,H -from nido-2,3-C2B4H8) parallel closely the chemical reactivity associated with such compounds. The negative ions are formed predominantly through a resonance-capture or a dissociative resonance-capture process.' Further data on the monoisotopic mass spectra of various carbaboranes e.g.C2B4Hs, Me2C2B,H, and Me,C2B8H, have been compiled.81' The nido-carbaborane C2B3H7 (8) reported briefly last year has been synthesized from the incomplete reaction of tetraborane(l0) and acetylene at 323 K and characterized from 'H and "B n.m.r. spectra.'2 The carbaborane (8) possesses an interesting property *' ( a ) A. B. Burg and T. J . Reilly Inorg. Chem. 1972 11 1962; ( 6 ) B. Lockman and T. Onak J . Amer. Chem. SOC. 1972 94 7923. C . L. Brown K. P. Gross and T. P. Onak ( a ) J . C . S . Chem. Comm. 1972 68; (6) J . Amer. Chem. Soc. 1972,94,8055; ( c ) E. McLaughlin and R. W. Rozett J . Phys. Chem., 1972,76 1860.D. A. Franz V. R. Miller and R. N. Grimes J . Amer. Chem. SOC. 1972,94 412. 8 The Typical Elements 189 in that it can easily rearrange to the planar anion C2B3H72- which is isoelectronic with the C,H5- ion. The rearrangement occurs on reaction of (8) with Fe(CO),, when the compound (n-C2B,H,)Fe(CO) is obtained.82 Several other metallo-derivatives of the smaller carbaboranes have been prepared; these may be classified into two types firstly those where the metal atom occupies a bridging or terminal position on the carbaborane framework and secondly those where the metal completes a closo-framework by bonding into the empty face of a nido-carbaborane. Both these types have been identified previously and now in the former class more information on the p-MR3-C2B4H7 (M = Si or Ge R = H or Me) compounds has been p ~ b l i s h e d ~ ~ " although when the bridging group is -SiH,Cl the reaction with a further mole of Na' C2B4H7- produces p,p'-SiH2-(C,B,H,), where two carbaborane fragments are linked by a silicon atom common to two three-centre B-Si bonds.83b A possible bonding scheme for the latter class using the compounds 1-MeMC2B4H6 (M = Ga or In) has been proposed following the crystal structure determination of the gallium derivative as shown in (9) and it is suggested that there is appreciable back-bonding from the metal d,,= orbital to the e2 antibonding orbital of the carbaborane ligand.84" Two further closo-compounds prepared are (n-2-MeC,B,H,)Mn(CO) ,84b from the action of Mn,(CO), on 2-MeC3B3H6 and (n-C,H,)Fe(C,B,H,) from the reaction scheme :84c NaC2B4H7 + (n-C,H,)Fe(CO),I - (n-C,H5)Fe(C0)2(C2B4H7) + NaI kv (n-C,H,)Fe(C,B,H,) 4 Oxidn' (n-C gH 5)Fe(C2B4H7) The crystal structure of the higher nido-carbaborane C,Me2B7H9 confirms almost exactly the structure proposed from n.m.r.results last year,85 in that the framework makes up a bicapped Archimedian antiprism with the 6-position missing the difference being that the two bridging hydrogen atoms are now located between the 7-10 and 9-10 positions.86" A similar framework for the C2B7 atoms occurs in the metallo-complex [Et,N]+ [Co(C,B,H,),]- where the anion is a sandwich compound with two distorted bicapped square anti-prisms one vertex (occupied by the Co atom) being common to both.86b Reports over the past two years that the 10-atom carbaborane anion C2B8HIo2- can act as a bridging ligand between two metal atoms have been 83 (a) M.C. Thompson and R. N. Grimes Znorg. Chem. 1972,11 1925; ( 6 ) A. Tabereaux and R. N. Grimes J . Amer. Chem. SOC. 1972 94 4768. 8 4 ( a ) R. N. Grimes W. J. Rademaker M. L. Denniston R. F. Bryan and P. T. Greene, J . Amer. Chem. SOC. 1972,94,1865; ( 6 ) J . W. Howard and R. N. Grimes Znorg. Chem., 1972,11,263; ( c ) L. G. Sneddon and R. N. Grimes J . Amer. Chem. SOC. 1972,94,7161. 8 5 D. W. A. Sharp M. G. H. Wallbridge and J. H. Holloway Ann. Reports ( A ) 1971,68, 253. 8 6 ( a ) J . C. Huffman and W. E. Streib J.C.S. Chem. Comm. 1972 665; ( 6 ) D. St. Clair, A. Zalkin and D. H. Templeton Inorg. Chem. 1972 11 377 190 D. W. A . Sharp M. G. H . Wallbridge and J H.Holloway substantiated from the novel reaction : (n-CSH,)Co(C,B8H10) + CoC1 + Na+(CsH5)- + (n-CSHS)Co(C2B8H1 o)Co(n-C5H5) The product which probably contains a 12-atom polyhedral fragment CoZCZB8, shows that polyhedral expansion reactions often used to prepare metallo-carbaboranes from closo-carbaboranes can also be applied to the closo-metallo-carbaboranes themselves.87a The geometry of the ligand (C2B,HloC5HsN)- in the sandwich compound [Et,N]+[(CzBgHl I)Co(C,B,HloC5HsN)]- has been determined from an X-ray study and is shown in Apart from the polyhedral expansion reaction described above two further methods for preparing metallocarbaboranes have appeared. One involves the intermediate icosahedral anion [TIR' RZC2B,Hg] - which yields closo-metallo-carbaboranes on treatment with halogeno-derivatives of the transition metals.The other involves the direct insertion of a nucleophilic metal species into suitable closo-carbaboranes thus closo-1,8-Me,C2B9H9 on treatment with Pt(PEt3) yields (PEt,),Pt[Me,C2BgH9] where the Pt" ion is suggested to occupy the vacant icosahedral site above a do-1,7-Me2C2BgHg fragment.88 In contrast P"" ( a ) W. J . Evans and M. F. Hawthorne J.C.S. Chem. Comm. 1972 611; ( 6 ) M. R. Churchill and K. Gold ibid. p. 901. J. L. Spencer M. Green and F. G. A. Stone J.C.S. Chem. Comm. 1972 1178 The Typical Elements 191 to these expansion reactions the opposite approach of using polyhedral con-traction reactions is also proving successful. While these types of reactions are known for the carbaboranes themselves they have also now been extended to the metallocarbaborane compounds and the first example of a polyhedral contraction where a polyhedral metallocarbaborane is transformed into its next lower homoiogue by the formal removal of a BH2+ group followed by a two-electron oxidation has been identified in the base degradation of [LCo{ x-(3)-1,2-C2BgHl,}]' to [LCO(~-(~)-~,~-C,B~H~~)]~ where L = CsH5- z = 0; or L = (3)-1,2-C2BgHIl2- and z = - l.89a*b In the area of dicarbollyl complexes the thermal rearrangement of (x-C5H5)-Co[n-(3)-1,2-C2BgH 1] and related compounds at 673-973 K yields compounds which contain all nine isomeric dicarbollyl ligands which are formed by migration of the cage C atoms over the polyhedral surface.90a Thermal decomposition of the arenediazonium salts [ArN,] [7t-7 8-C2BgH ,),Co] (Ar = Ph or C,H,Me) at 373 K affords new compounds of the type [Me4N] [(n-7 8-C2BgHlo)2C6H4C~] where the aryl group C6H4 is believed to occupy a bridging position between two C2B9Hlo fragments.90b In the heteroatom carbaborane ligands (l,7-B9H9CHE)2- (E = P or As) the phosphorus or arsenic atom can act as a donor site since when the [( 1,7-B,H,CHE),FeI2- anion is irradiated in the presence of a Group VI metal carbonyl the complex [( 1,7-B,H9CHE)M(C0)5]2-Fe2- is formed with the M(CO) fragment o-bonded to the carbaborane ligand."' A further discussion has appearedgod*' of the bonding and structure of the two aluminium compounds C,B,H ,AlMe2 and C2B9H ,AlEt reported last year.Polyhedral contraction reactions using base degradation reactions also occur with (7c-C,H,)Co(C2BloHl,) to yield [(n-C,H,)Co(CB,H,)]- this being a unique example of the removal of one C and three B atoms from a metallo-carbaborane and the CB,H,3- ligand may be classified into the general class CB,H,+13- of which the only other known example is CBloHl13-.91a The starting material first prepared last year is known to exist in three isomeric forms and the crystal structure of the red isomer shows the presence of a 13-vertex docosahedron in which the Co"' ion is linked directly to a C2B4 hexagon (1 1).The steric strain caused by such an arrangement becomes apparent in several distortions and irregularities in the remaining distances and angles of the cage framework.91b The bis-lithio salt of o-carbaborane LiCB oH,oCLi reacts with 1,3-dibromopropane to yield ( ~ L - C H ~ ) ~ - C ~ B ~ ~ H ~ ~ and this in turn forms metallocarbaboranes much like the dicarbollyl anion of the general types [M"+(C5B9H15)2]R-4 or (n-C5H5)M11'(C5BgH15).92a An unusual migration of the C,B,,H12 fragment occurs when thecompound (C2Bl0Hl2)Fe(n-C,H,)(CO), 8 9 C.J . Jones J . N. Francis and M. F. Hawthorne ( a ) J . C . S . Chem. Comm. 1972 900; ( 6 ) J . Amer. Chem. Soc. 1972 94 8391. 90 (a) M. K. Kaloustian R. J . Wiersema and M. F. Hawthorne J . Amer. Chem. Sac., 1972 94 6679; ( 6 ) J . N. Francis C. J. Jones and M. F. Hawthorne ibid. p. 4878; ( c ) D. C. Beer and L. J . Todd J . Organometallic Chem. 1972,36,77; (d) M. R. Churchill and A. H . Reis J.C.S. Dalton 1972 13 14; ( e ) ibid.p. 13 17. 9 1 ( a ) D. F. Dustin and M. F. Hawthorne J.C.S. Chem. Comm. 1972 1329; (6) M . R. Churchill and B. G. DeBoer ibid. p. 1326 192 D. W. A . Sharp M. G. H. Wallbridge and J. H . Holloway - w -(11) (12) is treated with halogen at 293 K and the new compound (12) is ~btained.’~’ Several a-bonded platinum complexes L,Pt( 1-Me-1,2-C2B ,H (where L = PPh, PPh2Me PMe, etc.) have been obtained via the action of the lithiocarbaborane on the L,PtC12 derivative^.'^' The crystal structure of the bis-carbaborane complex [NEt,]+[Co(C2Bl,Hl,),],- shows the metal atom to be surrounded by four C2B1 icosahedra in a tetrahedron but it is interesting that while the four nearest neighbours to the cobalt are carbon atoms these form a distorted tetrahedron e.g.one C-Co-C angle is 150.4” and since one boron atom is also quite close to the central atom the possibility of having 4 carbon atoms and one Co-H-B bond in the metal co-ordination sphere A simplified preparation of the o-carbaboranes C,B,,H, has been de~ised,’~’ and various bromo-substituted o-carbaboranes react with pyridine the un-substituted carbaborane being unreactive forming the 3,6-dipyridine derivatives, which are isoelectronic with the C2B10H122- anion.93b The reduction of o-carbaborane with a Na-THF mixture yields C2B,,H ,’- which on hydrolysis forms two isomeric C2Bl,H,,- ions one of which is unstable and rapidly inter-9 2 9 3 ( a ) T. E. Paxson M. K. Kaloustian G. M. Tom R. J . Wiersema and M. F. Hawthorne. J . Amer. Chem. SOC. 1972,94,4882; (b) L.1. Zakharkin L. V . Orlova B. V. Lokshin, and L. A. Fedorov J . Organometallic Chem. 1972 40 1 5 ; (c) R. Rogowski and K. Cohn lnorg. Chem. 1972,11 1429; (d) R. A. Love and R. Bau J . Amer. Chern. Soc., 1972.94 8274. (a) H. Beall lnorg. Chem. 1972 11 637; (6) J . Plesek T. Hanslik F. Hanousek and S. Hermanek Coll. Czech. Chem. Comm. 1972,37,3403; ( c ) G . B. Dunks R. J. Wiersema, and M. F. Hawthorne J.C.S. Chem. Comm. 1972 899 The Typical Elements 193 converts to the other stable form at 300 K. These ions may contain a methylene-type carbon atom within the polyhedral framework.93c Boron-Carbon Compounds. The structure of the cobalt-borabenzene complex Co( H,CSBOMe) determined from X-ray studies confirms that the C,B rings sandwich the metal atom and that the rings deviate only slightly from a planar The preparation of the 9-phenyl-9-bora-anthracene anion (1 3) has been achieved by allowing the neutral compound to react with LiBu‘ in THF.The ion is obtained as the lithio salt co-ordinated by 3.5 moles of THF and this solvent cannot be removed under The related lO-phenyl-9,lO-dihydro-9-bora-anthracene has also been prepared from tris-(2-benzhydryl-pheny1)boro~in.~~‘ The cyclic boratropylium and boracyclopentadienyl cations have both been identified in the mass spectra of cyclic derivatives of organo-boranes containing at least one B-N bond e.g. PhB-R’-CH,-C(HR2)-NR3 or Ph~-R’-(CH,),-~H (R’ = 0 S or NH).94d I Ph Mixed organoboranes R$BR2 can be easily prepared in high yield from the accessible thioboranes RiBSR by treating the latter with LiAlH in the presence of a suitable ~ l e f i n .~ ’ ~ Although as last year hydroboration will not be covered in this review it is worthwhile highlighting two papers. One deals with the measurement of the relative rates of the first and second steps of hydroboration, and it is observed that in the sequence BH + olefin -+ RBH -+ R,BH the rate of the second reaction is greater than that of the first and it is also concluded that for hydroboration reactions carried out in THF solution the initial reaction involves the adduct BH,,THF and the alkene.95b The other paper reports the isolation of the first monomeric dialkylborane dithexylborane (Me,C,H),BH, prepared from tetramethylethylene by the reaction scheme 9 5 c 9 4 ( a ) G. Huttner and B.Kreig Angew Chem. Internat. Edn. 1972,11,42; ( b ) P. Jutzi ibid., p. 5 3 ; ( c ) R. Van Ween and F. Buckelhaupt J . Organometallic Chem. 1972 43 241 ; (d) R. H. Cragg J . F. J. Todd R. B. Turner and A. F. Weston J.C.S. Chem. Comm., 1972 206. 9 5 ( a ) A. Pelter and D. N . Sharrocks J.C.S. Chem. Comm. 1972 566; ( 6 ) D. J. Pasto B. Lepeska and V. Balasubramaniyan J . Amer. Chem. SOC. 1972 94 6090; ( c ) E. Negishi J. Katz and H. C. Brown ibid. p. 4025 194 D. W. A . Sharp M. G. H. Wallbridge and J. H. Holloway H H \ / \ H H Other studies relate to the many diverse properties of the organoboranes. A series of para-substituted phenyl-dimesitylboranes have been prepared by the action of phenyl-lithium on the (Me,C,H,),BF derivative in order to study the variation in the photochemical behaviour with the substit~ent,’~~ and other workers have found that the U.V.spectra of para-substituted tribenzylboranes (XC,H,CH2),B contain an absorption in the region 240-285nm which is assigned to intramolecular charge transfer from the aryl group to the empty boron 2p-0rbital.~~’ An e.s.r. study of the trimesitylborane anion indicates some non-planarity in the rings probably due to steric hindrance between the ortho-methyl groups.96c A novel approach has shown that it is possible to stabilize boron-containing carbanions obtained from the action of a base having large steric requirements on an organoborane according to the scheme :97 The electrolysis of alkyl borates in the presence of olefins is of interest for alkyla-tion reactions and the anodic oxidation of trihexylborane in the presence of methoxide ions using a graphite electrode at 268 K yields hexyl radicals which dimerize to produce dodecane C 2H26 but at 253 K in the presence of butadiene only a small amount of dodecane is obtained the main products arising from the addition of C6H; to the butadiene radical cation to form C6R13-C4Hk followed by C7HI5CH=CHC7Hl5 etcg8 The first addition of a triorganoborane to a carbonyl group has been achieved using monomeric formaldehyde at 273 K Bu;B + CH20 + Bu”,OCH + CH,CH2CH=CH2 (1) Bu BOCH 2 B ~ n (2) o b y 6 (a) J.C. Doty B. Babb P. J. Grisdale M. Glogowski and J. L. R. Williams J . Organo-metallic Chem. 1972 38 229; ( 6 ) B. G. Rarnsey N. K. Griffith and H. van Willigan, J . Chem.Phys. 1972 57 86. 97 M. W. Rathe and R. Kow J . Amer. Chem. SOC. 1972,94,6854. 98 H. Shafer and D. Kock Angew Chem. Infernat. Edn. 1972 11 48 The Typical Elements 195 [reaction (211 although the presence of oxygen is required probably to generate alkyl free radicals otherwise reaction (1) occurs.99a The rate constants for the primary initiation state of borane autoxidation have been shown to increase through the series BuiB < BuiB < (CsH11)3B; the reactions are first-order in both borane and oxygen.'" The anions of the general type (BR,CN)- have been shown to co-ordinate to Cu' and Ag' salts forming compounds such as (Ph3P),M(NCBR3) which contain an M-N bond in both the solid and solution phases. The related compound (Ph,P),Cu(NCBH,) on the other hand appears to form a dimeric molecule, and preliminary X-ray results suggest the structure shown in (14).'0° f j H H n x /y B Ph (14) L = Ph,P (15) Two convenient routes to alkylboron halides have been reported.Trialkyl-boranes which have been prepared by the hydroboration of terminal cyclic or bicyclic olefins using a slight excess of borane react rapidly with boron trichloride at 383 K yielding RBCl compounds ''la and a-bromoethyldiethylborane under-goes very rapid rearrangement to s-butylethylboron bromide at 298 K under the influence of aluminium bromide.' O1 Finally the intriguing rearrangements of hydrocarbon ions which have been detected in the mass spectra of several boron compounds have now been found also for the phenylborolans (15) where X = Y = 0; X = 0 Y = S; or X = Y = S and again the tropylium ion C7H7 + has been detected.lo2 Compounds containing B- N and B -P Bonds. Ap ab initio MO study of t4e ygt unisolated iminoborane HBNH predicts a linear structure with a polar B=N bond which is best represented as a triple bond and which is comparable in v 9 ( a ) N. Miyaura M. Itoh A. Suzuki H. C. Brown M. M. Midland and P. Jacob J . Amer. Chem. SOC. 1972,94 6549; (6) P. B. Brindley and J . C. Hodgson. J.C.S. Chem. Comm. 1972 202. l o o S. J. Lippard and P. S. Welcker Inorg. Chem. 1972. 11 6 . ' " I ( a ) H . C . Brown and A. B. Levy J . Organometalfic Chem. 1972 44 233; (6) H. C. Brown and Y. Yamamoto J.C.S. Chem. Comm. 1972,71. R. H. Cragg G . Lawson and J . F. J . Todd J.C.S. Dalton 1972 878 196 D.W. A . Sharp M. G. H. Wallbridge and J. H. Holloway strength to the C-C linkage in a~ety1ene.l'~~ The low barrier to thermal isomer-ization in aminoboranes often prevents the isolation of cis- and trans-isomers, but now the trans-isomer of (PhCH,)(CH,)B+=N(Ph)(CH,Ph) at 251 K has been partially converted (15% in 10min) into the cis-isomer by irradiating at 253.7 nm.'03' A study of the I4N n.m.r. spectra of a series of simple aminoboranes, e.g. B(NR,), R'B(NR;), and R,BNH, has shown that a decrease in the shielding of the 14N nucleus occurs with increasing B-N bond order and that the signals are generally broad e.g. h for Et,BNMe is 222 H Z . " ~ ~ The n.m.r. spectra of some pyrazolyl compounds e.g. RB(pz),Mo(CO),(n-C,H,) (where pz = 1 -pyrazolyl) have indicated stereochemical non-rigidity in the pyrazolyl ligand,103d-f and the crystal structure of one complex [H2B(3,5-dimethyl-pyrazolyl)]Mo(CO),(C,H,) shows a trihapto-C,H ring and a severely bent boat form of the pyrazolyl chelate ring with a three-centre two-electron B-H-Mo bond.103g The synthesis of a range of pyrazolyl ligand compounds e.g.(pz)B(pz),Mn(CO),-,L pz = 1-pyrazolyl; L = P(OMe), n = 1 or 2; L = PMe or PBu'; n = 11 has been described using a photochemical reaction between (pz)B(pz),Mn(CO) and the ligand L.'03" Various reactions of aminoboranes reported include their use in the synthesis of sulphenamides according to the scheme :' 04a (R,N),B + 3PhSOMe -+ 3R,NSPh + B(OMe), A similar reaction with tertiary alkyl alcohols yields tris(t-a1kyl)boranes.I 04' Insertion reactions occur when CO, or COS is allowed to react with B(NR,), compounds and compounds such as Me,NB[OC(S)NMe,] and B[OC(O)-NHNMe,] are ~ b t a i n e d ." ~ ~ The halogen derivatives (R;N),BX - yield monomeric compounds (RiN),B(MRi) - (where M = P As or Sb R' = Me, R2 = Me or Et) on reaction with the lithio reagents LiMR~.'"" Cleavage of the B-N bond in the dimeric aminoborane (Me,NBH,) occurs on treatment with trimethylaluminium and in addition to the formation of (Me,NAlMe,) , (Me2A1H) and BMe the compound Al,Me,(NMe,),H is observed which consists of an eight-membered ring composed of Al,N,H atoms.105' Further properties of the monomeric methyleneaminoboranes e.g. BuiC NBPh have also been p~blished.'~~' New compounds containing €3-N bonds have been prepared by the action of PhBC1 or BCl on SPF,NH or P,N,F,NH, when boranes such as (SPF,NH),B and (P,N,F,NH),BPh are obtained.'05d l o 3 ( a ) N.C. Baird and R. K. Datta Inorg. Chem. 1972 11 17; (6) K. G . Hancock and D. A. Dickinson J . Amer. Chem. SOC. 1972,94,4396; ( c ) W. Beck W. Becker H. Noth, and B. Wrackmeyer Chem. Ber. 1972 105 2883; (d) P. Meakin S. Trofimenko and J . P. Jesson J . Amer. Chem. Soc. 1972,94 5677; ( e ) J . L. Calderon F. A. Cotton and A. Shaver J . Organometallic Chem. 1972 37 127; (f) ibid. 1972 38 105; (g) F. A. Cotton J . L. Calderon M. Jeremic and A. Shaver J.C.S. Chem. Comm. 1972 727; (h) A. R. Schoenberg and W. P. Anderson Inorg. Chem. 1972 11 85. l o 4 ( a ) R. H. Cragg J. P. N. Husband G. C. H. Jones and A. F. Weston J . Organo-metallic Chem.1972 44 C37; (6) I. Kronawitter and H. Noth Chem. Ber. 1972 105, 2423; (c) A. Meller and A. Ossko Monatsh 1972 103 577. ( a ) W. Becker and H. Noth Chem. Bet-. 1972,105 1962; ( b ) J . D. Glore R . E. Hall and E. P. Schram Inorg. Chem. 1972 11 550; (c) M. R. Collier M. F. Lappert R. Snaith, and K. Wade J.C.S. Dalton 1972 30; ( 6 ) H. W. Roesky Chem. Ber. 1972,105 1726. l o The Typical Elements 197 The crystal stucture of dimeric (Ph,PBI,) shows a four-membered non-planar B-P ring with a dihedral angle of 30" the complete molecule possessing an axis of near two-fold symmetry.'06 Compounds containing B-0 and B-S Bonds. The variation in the electrical conductivity of an H,O-B,O melt over a range of compositions has led to the suggestion that two conduction mechanisms exist; in a B(OH) solution a proton-jump process occurs while in a melt of B,O containing only a trace of water the usual ionic migration is present.'07" A study of boric acid-borate equilibria using a hydrogen-electrode concentration cell suggests that in dilute solution the equilibrium B(OH) + OH- S B(OH),- occurs while in more concentrated solution B2(OH),- B,(OH),O- and minor amounts of B,(OH),,,- and B,(0H),,3- occur.1o7b The B-0 bond dissociation energy in B(OPh) has been calculated as 437 kJ mol- from thermochemical data which makes it a relatively weak bond compared with other B(OR) C O ~ ~ O U ~ ~ S .' ~ ~ ~ The crystal structure of tetra-acetyl diborate (AcO),B.O.B(OAc) shows it to consist of two distorted boron-oxygen tetrahedra sharing a vertex with all other vertices connected to the carbon atoms of the four acetoxy-groups; two of these groups have only one B-0-C bond whereas the other two have two such bonds."*" The difference between B203 and B,S arises in part from the lack of interaction of the B atom with the fourth S atom in the solid phase of B2S3 this suggestion having been made following v.p.measurements of B,S,(g) and B4S,(g) over B,S as determined mass spectrometrically.'08b Another difference of B(SMe) from B(OMe) has also been detected by this technique in that while the latter fragments into relatively few ions due to the strong B-0 bond the former gives many more ions together with high yields of rearrangement ions such as MeSCH,' and MeSSMe+' (ref. 109~). The novel use of thioboranes in the preparation of borazines by interaction with hydroxy- or mercapto-amines has been reported.'0gb A "B n.m.r.study of potassium tetraborate K20,5B,0 ,8H,O at concentra-tions > 0.4 moll- ' shows the presence of an equilibrium between B(OH) and B(OH)4- possibly involving B303(OH)4- or B,O,(OH),-.' The crystal structure of potassium diborate K,0,2B203 shows a single three-dimensional borate anion framework composed of mutually linked BO triangles making up diborate and triborate groups in which 2 of the 3 boron atoms are tetraco-ordinated.' Ob I o 6 G. J . Bullen and P. R. Mallinson J.C.S. Dalton 1972 1143. l o ' ( a ) H. Kodama T. Yokokawa and K . Niwa Bull. Chem. SOC. Japan 1972 45 776; (6) R. E. Mesmer C. F. Baes and F. H . Sweeton Znorg.Chem. 1972,11,537; ( c ) J. T. F. Fenwick and J. W. Wilson J.C.S. Dalton 1972 1324. ( a ) A. D. Negro L. Ungaretti and A. Perotti J.C.S. Dalton 1972 1639; (6) H. Chen and P. W. Gilles J. Phys. Chem. 1972 76 2035. l o 9 (a) R. H. Cragg J. F. J. Todd and A. F. Weston J.C.S. Dalton 1972 1373; (b) R. H. Cragg and A. F. Weston J.C.S. Chem. Comm. 1972 79. ' l o (a) H. D. Smith and R. J . Wiersema Znorg. Chem. 1972 11 1152; (6) J . Krogh-Moe, Acra Crysr. 1972 B28 3089 198 D. W. A . Sharp M. G. H. Wallbridge and J. H. Holloway Compounds containing Boron-Halogen Bonds. This section discusses the boron trihalides their co-ordination compounds the sub-halides and the tetrahalogeno-borate ions. The nature of metal surfaces has been studied by the adsorption of BF and BCl ; the former is adsorbed without dissociation on V Fe Ni Cu and Pd films ; the complex formed is stable in air but carbon monoxide will displace the BF, from Ni and Pd but not V or Cu surfaces.' Calculations using the Long-Plane equation which relates M=X bond polarizability to covalent character satis-factorily for Group IV compounds have shown that the equation also provides reasonable agreement for the boron trihalides (except the fluoride). ' ' The use of the boron halides as synthetic reagents for halogen-transfer reactions has been further exploited for the preparation of rhenium halides,' [L2PtXIz2+ (X = F C1 or Br; L = Bu:P) cations,''3b and F,P(OR),_. from ReCl, L,PtY (Y = C1 Br NCO or N,) and P(OR) respectively. Some interesting reactions occur with transition-metal compounds ; with Co,(CO) the adducts BX ,NEt (X = C1 or Br) form cluster compounds of the type Co3(CO),-[COBCl,NEt,] (16) and CO,(CO)~[COBC~,NE~,] depending on the molar (16) L = BC12N(C2H5)3 ' I 1 R.Sheets and G. Blyholder J . Amer. Chem. SOC. 1972 94 1434. 'I2 R. J. H. Clark and P. D. Mitchell Inorg. Chem. 1972 11 1439. ' I 3 ( a ) M. A. Bush P. M. Druce and M. F. Lappert J.C.S. Dalton 1972 5 0 0 ; ( b ) P. M. Druce M. F. Lappert and P. N. K. Riley ibid. p. 438; (c) H. Binder and R. Fischer, Z. Naturforsch. 1972 27b 753 The Typical Elements 199 ratios of the reactants used.' lbVb With the zerovalent platinum complex Pt(PPh,) boron trichloride forms a 1 2 adduct (PPh,),Pt(BCl,) and the 1 1 compound (PPh3)2PtBC13 was also obtained by displacement from (PPh3),-PtSiF .' 14' Halogen exchange occurs as above when the carbonyls M(CO),-PPh,SnMe (M = Cr Mo or W) react with the trihalides and the corresponding M(CO),PPh,SnMe,Cl or M(CO),PPh,SnMeBr complexes are obtained with BCl and BBr respectively.' 14d The silylamine (Me,Si),NH reacts with BF below 273 K forming the simple 1 1 adduct but above 273 K elimination of Me,SiF occurs and Me,SiNH ,BF, together with borazines e.g.F,B,N,(SiMe,) are formed.' 15a The same 1 1 adduct in the presence of PriEtN,BF eliminates HF to form (Me,Si),NBF,, and this in turn reacts with Me,SiNR (R = Me Et Pr" or Bun) at 423 K yielding (Me,Si),NB(F)NR,. ' ' 5b The reactivity of the trihalides towards silanes appears to increase through the series BF < BCl - BBr since BCl is reduced by the MeSiH while BF is not and BBr is reduced also by ClSiH .' 15' The gaseous species produced by heating silicon tetrafluoride with silicon (or silicon carbide) at 1473-2123 K when condensed with BF at 81 K produces F,SiBF in addition to the known mixed fluoride F3SiSi(F2)BF,.'*5d The crystal structure of the benzoylacetonate BF compound (17) obtained from interaction of the ligand with BF, shows the boron atom to be in a near tetrahedral environment and chelated by the two oxygen atoms.''6 With regard to the co-ordination compounds formed by the boron trihalides, the mechanism of formation of the Me,N,BX and mixed halide compounds Me,N,BX,Y,- has been studied and the results suggest that halide exchange occurs without B-N bond dissociation (contrary to earlier suggestions) at least in solution and only if an excess of the boron halide is present.In the gas phase it is likely that the B-N bond does dissociate since here exchange of the B atom does occur." 7 a The slower exchange rate using bases containing N ligand atoms, compared with 0 donor systems allows all twenty possible adducts of trimethyl-amine with mixed boron halides to be identified using 'H n.m.r. spectra."7b This slow rate of exchange has also allowed the determination of the stoicheio-metry and relative basicity of a number of nitrogen ligands towards BF and BCl, using 'H and "F n.m.r. In mixtures of X,B,OMe (X = F or Cl), near statistical amounts of the mixed halide adducts are obtained in mixtures of the trifluoride and trichloride adducts as identified from "B or "F n.m.r.spectra, ' l 4 ( a ) G. Schmid and B. Stutte J . Organometallic Chem. 1972,37,375; (b) G . Schmid and V. Batzel ibid. 1972 46 149; ( c ) T. R. Durkin and E. P. Schram Inorg. Chem. 1972, 11 1054; (d) H. Noth and S. N . Sze J . Organometallic Chem. 1972,43 249. " ' G. Elter 0. Glemser and W. Herzog ( a ) Chem. Ber. 1972,105 115; ( 6 ) Inorg. Nuclear Chem. Letters 1972,8 191 ; ( c ) M. A. Ring ibid. p. 421 ; (6) D. L. Smith R. Kirk and P. L. Timms J.C.S. Chem. Comm. 1972 295. ( a ) B. Benton-Jones and J. M. Miller Inorg. Nuclear Chem. Letters 1972 8 485; ( b ) B. Benton-Jones M. E. A. Davidson J. S. Hartman J . Klassen and J. M. Miller J.C.S. Dalton 1972 2603; (c) A. Fratiello R. E. Schuster and M. Geisel Inorg.Chem. 1972, 11 1 1 ; (d) M. J. Bula D . E. Hamilton and J. S. Hartman J.C.S. Dalron 1972 1405; ( e ) J. E. Drake and B. Rapp ibid. 1972 2341. ' l d A. W. Hanson and E. W. Macaulay Acta Cryst. 1972 B28 1961 200 D . W. A . Sharp M. G. H. Wallbridge and J. H. Holloway but decomposition reactions occur when B-Br or B-I bonds are Further studies of exchange processes have been made on PH,-BC1,-BBr and other mixtures of the trihalides and complexes such as H,P,BClBrI and H,P,BX,Y (X # Y = C1 Br or I) have been identified.'17e The 'H n.m.r. spectra of mixtures of BF,-MeOH in liquid sulphur dioxide show that at molar ratios MeOH BF > 2 1 the products are the 1 1 adduct MeOH,BF and MeOBF,- MeOH,+.1'8" Other 1 1 adducts have been characterized with tetramethylurea (where 0 acts as the donor site),' ' 8b aromatic aldehydes,' ' *' and phosphites (RO)3P.118d The kinetics of the exchange reaction RY + BX,+ RX + BX,Y (R = Pr" Pr' Bun Bus or Me,Si ; Y = C1 or Br ; X = Br or I) where X is heavier than Y have been studied in carbon tetrachloride or cyclohexane solution using 'H and "B n.m.r.spectra and the results suggest that the inter-mediate RY,BX is i n v ~ l v e d . ' ~ ~ The direct reaction of Fe" salts dimethyl-glyoxime and BF ,Et,O [or B(OH),] in an alcohol leads to encapsulated metal complexes according to the scheme : Fez+ + 3dmgH + 2B(OH) + 2ROH -+ [Fe(dmg),(BOR),] + 2H+ + 6HOH (R = Me Et Pr' Bun or OH) With BF ,Et,O the compound [Fe(dmg),(BF),] is obtained and the cage-like nature of this compound has been established from unpublished X-ray data.'" Alkyl- and aryl-seleno-halogenoboranes e.g.MeSeBI and (PhSe),B have been prepared by the action of the organoselenane on the alkyl boron halides; their properties differ in that MeSeBI and MeSeB(Me)I are stable trimers (MeSe),BI and MeSeB(Ph)I are monomeric and the aryl compounds ArSeBI exhibit low thermal stability and decompose to (ArB),Se, or (ArSe),B in the case of the chloro derivative ArSeBCI .12 l a y b As in the case of the trihalides exchange reactions have also been observed in the tetrahalogenoborate ions BX,-(X = F C1 Br or I) using "B n.m.r. spectro-scopy and signals arising from the mixed ions have been observed.' A mixture of BC1,-PC1,-NH,Cl yields chlorophosphazonium tetrachloroborates [Cl(C1,P=N),PCl3]BCl ,' 2 2 b and dioxygenyl tetrafluoroborate established as O,+BF,- from i.r.studies reacts with xenon near 173 K to form a white solid which decomposes at 243 K to form another solid believed to be FXeBF which is assumed to contain a covalent Xe-B bond.'''' The crystal structure of ''* ( a ) K. L. Servis and L. Jao J . Phys. Chem. 1972,76 329; ( b ) J. S. Hartman and G. J. Schrobilgen Canad. J . Chem. 1972 50 713; (c) M. Rabinovitz and A. Grinvald J . Amer. Chem. SOC. 1972 94 2724; (d) T. Reetz Inorg. Chem. 1972 1 1 650. M. Goldstein L. I. B. Haines and J. A. G. Hemmings J.C.S. Dalron 1972 2260. S . C. Jackels D. S. Dierdorf N. J. Rose and J. Zekter J.C.S. Chem. Comm. 1972 1291. W. Siebert and A. Ospici ( a ) Chem. Ber. 1972 105 454; ( 6 ) ibid. p. 464. (a) J.S. Hartman and G. J. Schrobilgen Inorg. Chem. 1972 11,940; ( 6 ) K. Niedenzu, I . A. Boenig and E. B. Bradley Z . anorg. Chem. 1972,393,88; ( c ) C . T. Goetschel and K. R. Loos J. Amer. Chem. SOC. 1972,94. 3018. ' The Typical Elements 201 [Ni(en),(H,O)BF,]BF reveals a cis-configuration for the two ethylenediamine molecules about the nickel atom with the remaining octahedral positions being occupied by H,O and BF, the latter being bonded through a fluorine bridge atom as Ni-F-BF .12, The action of copper vapour on boron trichloride yields diboron tetrachloride, B2C14 when the two reactants are condensed onto a surface at 81 K,124a and the action of this reagent on various cyclopropanes leads to ring cleavage and products which probably contain the dichloroboryl groups in the 1,3-positions on the hydrocarbon chain e.g.Cl,B.(CH,),.BCl .12,' Another study of the action of B,Cl on SiC1 or SiF at 81 K shows that novel boron-silicon com-pounds such as Cl,SiBCl are formed while when CO or PF are also present, other compounds (SiCl,),(BCl,)B,L (L = CO or PF,) are formed although in very low yield. 24c The condensed compound B,F which had been previously characterized has also been further studied and it is now believed to possess the structure shown in (18) which would be consistent with its reactions with a series of ligands when adducts of the type (BF,),B,L (L = CO PF PCI PH ASH,, or SMe,) are formed.' 24d Heterocyclic Compounds containing Boron. This year the heterocycles containing boron-carbon bonds as found in the bora-anthracene ion for example are discussed in the section dealing with boron-carbon compounds.The compounds are again discussed in the order of B-N B-0 and B-S heterocycles. The electronic structure of the ground state of the parent tetrazaboroline H,N,BH has been calculated,'25u and a summary of several routes to the B-halogen (or -pseudohalogen) derivatives has been given.'25b In the borazine compounds another calculation of the electronic energy shows that the planar D, molecule is preferred energetically and supports the generally accepted view A. A. G. Tomlinson M. Bonamico G. Dessy V. Fares and L. Scaramuzza J . C . S . Dalton 1972 1671. 1 2 4 ( a ) P. L. Timms J . C . S . Dalton 1972 830; (b) M. Zeldin and A. Rosen J . Organo-metallic Chem. 1972,34,259; (c) R.W. Kirk D . L. Smith W. Airey and P. L. Timms, J . C . S . Dalton 1972 1392. ( a ) D. R. Armstrong P. G. Perkins J . M. Scott and J. J . P. Stewart Theor. Chim. Acta, 1972 26 237; ( b ) B. Hessett J. B. Leach J. H. Morris and P. G. Perkins J . C . S . Dafron, 1972 131 202 D. W. A . Sharp M . G. H . Wallbridge and J. H . Holloway that the B and N atoms carry positive and negative charges respectively.'26a From the 'H n.m.r. spectrum over a range of temperatures the broad lines have been analysed to yield estimates of the nuclear quadrupole coupling constants' 26b and spin-lattice relaxation times.' 26c The chemical ionization mass spectrum of borazine has yielded a value of the proton affinity as 853 kJ mol-' so that it should be considered as a relatively strong base.'26d Evidence for a borazyne intermediate B,N,H in the photochemical decomposition of borazine has been suggested to occur via the scheme : B3N3H6* + B3N3H6** -+ B3N3H4 + H2 The B,N,H6** species is suggested to arise from an internal conversion process and is a molecule in a vibrationally 'hot' ground state.12' Several new borazines have been prepared including the ortho- and para-substituted isomers H,ClB,-N3H2Me and the relative amount of each isomer (30% ortho- and 70% para-) suggests that some directive influence is operating in the original preparation from H,B,N,H,Me and HgC1 .128a Routes to 1,3,5-triaryl- and 1,3,5-triaryl-2,4,6-trichloro-borazine have been devised and it has been found that borazine formation is inhibited by 2-ortho-substitution when compounds such as (ArNH),BH and ArNHBCl are obtained instead.'28b The NN'N"-trimethyl-B-tris-(Cp)-borazines have been synthesized by the action of sodium cyclopenta-dienide (NaCp) on the corresponding BB'B"-trichloro-derivative,' 28c and similar reactions using Grignard reagents have afforded all ten possible B-phenyl, -methyl and -chloro substituted NN'W-trimethylborazines.' 28d While borazine derivatives are obtained in reactions of 3-butenylamine with different boranes, when the N-methylamine is used only the partially saturated heterocycle (19) is p r ~ d u c e d .' ~ ~ " In a similar vein other reactions have shown that although BH, in THF reacts with RNH and R2NH compounds to form monoaminoboranes R2NBH, it requires am-diamines amino-alcohols or glycols to react further to yield the heterocycles (20; n = 2 or 3; X = 0 S or NR; Y = 0 S or NR).129b CYMe BH x\,/y - H I Z 6 ( a ) D.R. Armstrong and D . T. Clark Theor. Chim. Acra 1972 24 307; ( b ) E. K. Mellon B. M. Coker and P. B. Dillon Inorg. Chem. 1972 11 852; (c) G. M. White-sides s. L. Regen J. B. Lisle and R. Mays J . Phys. Chem. 1972 76 2871; (4 L. D. Betowski J. J . Solomon and R. F. Porter Inorg. Chem. 1972 11 424. 12' M. A. Neiss and R. F. Porter J . Amer. Chem. SOC. 1972 94 1438. 1 2 * (a) 0. T. Beachley J . Amer. Chem. SOC. 1972,94,4223; ( b ) I. B. Atkinson D. B. Clapp, C. A. Beck and B. R. Currell J.C.S. Dalton 1972 182; (c) B. L. Therrell and E. K. Mellon Inorg. Chem. 1972,11 1137; (4 L. A. Melcher J. L. Adcock and J. J. Lagow-ski ibid.p. 1247. ( a ) H. Wille and J. Goubeau Chem. Ber. 1972 105 2157; ( b ) K. Niedenzu I. A. Boenig and E. F. Rothgery ibid. p. 2258; ( c ) A. B. Burg Inorg. Chem. 1972,11 2283 Me Me I N-/ H B, S-Me/ i2 / / N B H2 /Me Me \ R ' R2 Metal Borides. The structure of a tetragonal boron framework containing alu-minium and beryllium atoms of formula AlBeo.,B24.2 shows the Be atoms to be statistically distributed within the B, icosahedra with the A1 atoms in holes which are surrounded by a tetrahedron of four B, i~osahedra.'~' The crystal structure of W21r3B6-x (where x = 1) has been solved together with that for the compound MoIrB . In the latter there are B groups present while in the former there is a more statistical distribution of the metal Barium diboride BaB has been identified as well as BaB in mixtures of barium and boron at 1173-1 573 K ; the BaB has a hexagonal structure and can be easily hydrolysed to liberate b ~ r a n e s .' ~ ~ ' The magnetic behaviour of a series of rare-earth tetraborides (e.g. PrB is ferromagnetic SmB is antiferromagnetic and ErB is metamagnetic) has been rationalized using different indirect exchange models.133c I3O ( a ) S. G. Shore J. L. Crist B. Lockman J. R. Long and A. D. Coon J.C.S.Dalron, 1972 1123; (6) I. R. McKinley and H. Weigel J.C.S. Chem. Comm. 1972 1051 ; (c) A. Karpides and J. Graf Inorg. Nuclear Chem. Letters 1972 8 161. M. Schmidt and F. R. Rittig Z. anorg. Chem. 1972,394 152. 1 3 * K. Krogmann and H. J. Becher Z. anorg. Chem. 1972.392 197. 1 3 3 ( a ) P.Rogl F. Benesovsky and H. Nowotny Monatsh 1972,103,965; (6) K. Torkar, H. Krischner and E. Hitsch ibid. p. 744; ( c ) K. H. J. Buschow and J. H. N. Creyghton, J . Chem. Phys. 1972,57 3910 204 D. W. A . Sharp M. G. H. Wallbridge and J . H. Holloway Aluminium.-As in previous years the compounds containing aluminium-carbon bonds provide the centre of interest although several other papers have provided novel areas of chemistry. For example i.r. evidence has been presented to support the existence of an aluminium carbonyl Al,(CO), prepared by con-densing carbon monoxide and aluminium atoms in a Kr matrix at 20K.'34u The first definite evidence for the existence of an aluminium-sulphate complex has been obtained from a study of 27Al n.m.r. spectra of the [A1(H20)6]3+ ion in the presence of SO:- ions; the most likely complexes in these solutions appear to be Al(H,O),(SO,)+ together with small amounts of Al,(OH),-( H20), + .' 4b Compounds containing Al-H Bonds. The direct synthesis of alkoxyaluminium hydrides has been achieved in benzene solution at 423 K under 85 atm pressure from a mixture of Na Al MeOCH,CH,OH and H2.135a An alternative procedure is:'35b 3Na + 3NaAl(OR) + 3A1+ 6H2 -+ 2NaH + 4NaAIH(OR) + 2A1+ 3H2 2NaH + 4NaAlH(OR) + 2A1 + 3H2 -+ 6NaA1H2(OR), The thermal decomposition of complex metal hydrides such as LiAlH or KAlH, has been shown to occur through the complexes M,AlH6 although amine complexes of these hydrides MAIH,,L (where L = tertiary amine M = Li or Na) appear to be more ~ t a b 1 e .l ~ ~ ' The ether solution equilibrium LiBH + Al(BH,)3 =Li[Al(BH,),] has been studied using "B n.m.r. spectroscopy and earlier suggestions that the equilibrium is shifted towards Li[Al(BH,),] as the temperature is decreased have been confirmed.' 5d Compounds containing Al-C Bonds. The direct synthesis of some as yet un-identified organo-aluminium compounds by condensing monatomic aluminium vapour with unsaturated organic compounds (e.g. propene) at 77 K has been r e ~ 0 r t e d . l ~ ~ Organo-aluminium compounds e.g. EtAlCl have been used to catalyse the exchange between aromatics (benzene azulene etc.) and deuteriated aromatics,' 7a and for tritium labelling of organic molecules using tritiated water. 7b Exhaustive methylation (i.e. complete deoxygenation of functional groups) can be achieved using trimethylalane ; thus tertiary alcohols and ketones yield alkanes and gem-dimethyl compounds re~pectively.'~ 7c Several structures of aluminium alkyl compounds have been solved using gas-phase electron-diffraction methods.The cyclopentadienyl derivative 1 3 * ( a ) A. J . Hinchcliffe J. S. Ogden and D. D. Oswald J.C.S. Chem. Comm. 1972 338; (b) J. W. Akitt N . N. Greenwood and B. L. Khandelwal J.C.S. Dalton 1972 1226. 1 3 5 B. Casensky J. Machacek and K. Abrham ( a ) Coll. Czech. Chem. Comm. 1972 37, 1178; (b) ibid. p. 2537; ( c ) J . A. Dilts and E. C. Ashby Inorg. Chem. 1972 11 1230; (d) M. Ehemann H. Noth and G. Schmidt-Sudhoff 2. anorg. Chem. 1972 394 33. 1 3 6 P. S. Skell and L. R. Wolf J . Amer. Chem. SOC 1972 94 7919.lJ7 J. L. Garnett M. A. Long R. F. W. Vining and T. Mole ( a ) J . Amer. Chem. SOC., 1972 94 5913; (6) ibid. p. 8632; (c) A. Meisters and T. Mole J.C.S. Chem. Comm., 1972 595 The Typical Elements 205 Me,Al(C,H,) is monomeric in the gas phase and the structure suggested at present is shown in (23); it may be that the asymmetrically bonded CSH group need only act as a three-electron ligand of the n-ally1 type for the aluminium atom to complete its octet.'38a In contrast the i.r. and Raman spectra of the compound in the solid state indicate the presence of pentahapto rings of near D, sym-m e t r ~ . ' ~ ~ At 443K the hydride Me,AlH is dimeric in the vapour phase as reported last year.138c The fluoride derivative (Me,AlF) is a tetramer and appears to contain an eight-membered ring in chair-boat configuration of Cs symmetry with two of the four aluminium atoms lying in the mirror plane.'38d Other studies on Me,Al,NMe in the gas phase confirm the near tetrahedral symmetry around both the aluminium and nitrogen atoms.' 8e Several X-ray studies on aluminium alkyl derivatives have also been reported.Following an earlier study of [Na(THF),],[Me,AlC ,-,H8] the crystal structure of [Na(THF),],[Me,AlC,,H,,] has now been solved and shows a contact ion-pair complex with two cations complexed to the dimeric anion. The anion itself consists of two 1,4-dihydro-1,4-anthrylene groups fused into the anion via the Me,Al groups.' 9a The cis- and trans-isomers of (Me,AlNHMe) have been prepared by heating Me,AlNH,Me to 323 K and separating by fractional sub-limation.The solid isomers are stable in vacuum but interconvert in solution, and both decompose above 423 K to yield several products including (MeAlNMe) .139b The crystal structures of both the cis- and trans-isomers have been determined ; the former contains all the N-Me groups in the equatorial positions with the (AlN) ring in the chair configuration while for the latter the configuration at one of the N-Me groups is reversed and the (AlN) ring is now of the skew-boat type.139c Complete parameters for (AlPh,) and (Me,AlPh), both of which contain bridging phenyl groups in the solid state, have been p ~ b l i s h e d . ' ~ ~ ~ ~ ' H / \ Me Me 1 3 8 (a) D . A. Drew and A. Haaland J.C.S. Chem. Comm. 1972 1300; ( 6 ) A. Haaland and J. Weidlein J .Organometallic Chem. 1972,40 29; (c) A. Almenningen G. A. Ander-son F. R. Forgaard and A. Haaland Acta Chem. Scand. 1972 26 2315; ( d ) G. Gundersen T. Haugen and A. Haaland J.C.S. Chem. Comm. 1972 708; (e) G. A. Anderson F. R. Forgaard and A. Haaland Acta Chem. Scand. 1972 26 1947. 139 (a) D. J. Brauer and G. D. Stucky J . Organometallic Chem. 1972 37 217; (b) K . J . Alford K. Gosling and J. D. Smith J.C.S. Dalton 1972,2203 ; ( c ) G. M. McLaughlin, G. A. Sim and J. D. Smith ibid. p. 2197; J. M. Malone and W. S. McDonald (d) ibid., p. 2646; ( e ) ibid. p. 2649 206 D. W. A . Sharp M . G. H. Wallbridge and J. H. Holloway The exchange of methyl groups in mixtures such as Al,Me,-GaMe, A12Me6-ZnMe, and Al,Me,-AlMe ,B (where B = pyridine THF etc.) has been studied using 'H n.m.r.spectroscopy. In general the kinetics follow the simple first-order dissociative or second-order associative rate law but in Al,Me,-AlMe ,CSH,N exchange the process probably contains contributions from both pathways. When the base involves a Group VI donor atom a base-assisted associative exchange mechanism is proposed involving interaction of the second lone pair on the donor atom with A1,Me,.'40" New values for the heats of dissociation of liquid and gaseous trimethyl- and triethyl-alane have been obtained and are different from previously reported values being typically 81.5 kJ (mol dimer)-for liquid and gaseous A12Me6 and 71.0 and 76.4kJ (mol dimer)-' for liquid and gaseous Al&t, respectively.'40b A variety of reactions involving organo-aluminium compounds have been reported.The crystal structure of one of the transition-metal complexes reported last year [(n-CSH,)W(C0)3A1Mez]z is shown schematically in (24) ; the twelve-membered ring is slightly puckered with approximate octahedral and tetrahedral co-ordination around the tungsten and aluminium atoms re~pectively.'~~" Interaction between bridging carbonyl groups in [(C,H,)Fe(CO),] [(C,H,)-Ru(CO),], and [(C,H,)Mo(CO),] and AlEt has been inferred from an i.r. study of the solutions,141b and simple Mo-CO-Al(Ga) bridges are also apparently formed when Mo(phen)(PPh,),(CO) (phen = o-phenanthroline) is mixed with AlEt, AlBu; or GaMe .l4lC The relative base strengths of a series of dinitrogen and carbonyl complexes towards AlMe in benzene solution have been determined using 'H n.m.r.spectroscopy the results indicating a decrease in the order THF > trans-ReClN,(PMe,Ph) > trans-Mo(N,),(dpe) > trans-W(N,),(dpe) > mer-OsCl,N,(PEt Ph) (where dpe = Ph ,PCH ,CH PPh,).'4' Trimethylalane has been found to-react with (C,H,),ZrH to yield the hydrogen-bridged compound (25). ' 4' = H / \ \ / (C H ,) Zr( HAlMe,) (Me AlH)Zr(C H& H (25) The gas-phase thermal reaction of monomeric AlMe molecules with ethylene has been studied over the temperature range 455-549 K. The reaction scheme can be summarized as : 14" ( a ) T. L. Brown and L. L. Murrell J. Amer. Chem. SOC. 1972,94 378; (b) M. B. Smith, J. Organometallic Chem. 1972 46 3 1 . 14' ( a ) G. J. Gainsford R. R. Schrieke and J . D. Smith J.C.S.Chem. Comm. 1972 650; (6) A. Alick N . J. Nelson D. Strope and D. F. Shriver Znorg. Chem. 1972 1 1 2976; ( c ) D. F. Shriver and A. Alick ibid. p. 2984; (6) J. Chatt R. H. Crabtree and R. L. Richards J.C.S. Chem. Comm. 1972 534; ( e ) P. C. Wailes H. Weigold and A. P. Bell, J . Organometallic Chem. 1972 43 C29 The Typical Elements 207 Me,Al + C2H4 -+ Me,Al-CH,-CH,-CH -@-+ Me,AlH + CH,=CHCH, &A Me,AlC,H, The kinetic results cannot be rationalized in terms of the often quoted simple quadrupolar four-centre transition state and instead an intermediate involving the olefin co-ordinatively bonded to the aluminium atom is p r ~ p o s e d . ' ~ ~ " The essential presence of an AlR fragment not co-ordinated with any ligand has also been demonstrated from a kinetic study of AlEt with oct-1-ene in diphenyl ether.142b The presence of trialkylalanes has been found to catalyse the addition of HCN to a-enones through the intermediate formation of R,AlCN com-pounds. 142c Studies on co-ordination compounds derived from organo-aluminium compounds include a ' H n.m.r. examination of various vinyl compounds, including (C,H,),M,NMe (M = Al Ga or In),1430 and of adducts formed from AlEt or Et,AlCl and ditertiary phosphines [Ph,P(CH,),PPh, where n = 1,2,3, 4 or 6].143b The synthesis of Et,AlI,NHMe, which is monomeric in benzene, has been reported from mixing AlEt with the salt Me,NH,+I-; heating the adduct to 413 K liberates ethane while Et(I)AlNMe is formed.143c The cyclic compound Al,Me,(NMe,),H reacts with trimethylamine in two ways ; when the aluminium compound is not very pure (Me,AlNMe,) and Me,AlH,NMe, are formed whereas with pure material Al,Me,(NMe,),H and Me,AlH,NMe, are formed.'43d With oxygen as the ligand donor atom a series of acetylacetone (acac) complexes have been prepared by the action of acac on Me,Al Me,AlCl, or MeAlCl, with the formulae Me,Al(acac) (acac)AlCl, and Me(Cl)Al(a~ac),'~~" and a series of quinolinolato-complexes of the type R,MQ (R = Me Et or Bu' ; M = Al Ga or In; Q = anion of quinolin-8-01) has been prepared.144b Lead oxide PbO is alkylated to yield PbMe and (Me,Al),O when heated with tri-methylalane at 408 K,14,' and the formation of a Group IIIB-tin bond results from the action of LiSnMe on a metal alkyl to yield Li(Me,SnMMe,) (M = Al, Ga In or Tl) although the aluminium compound is the least stable and de-composes after 24 h to a mixture of LiAlMe, SnMe, and Li[Sn(SnMe,),].'44d An Al-S(or P)-Ni linkage is said to result from the reaction: 14' ( a ) K.W. Egger and A. T. Cocks J . Amer. Chem. SOC. 1972 94 1810; (6) P. E. M. Allen A. E. Byers and R. M. Lough J.C.S. Dalton 1972 479; ( c ) W. Nagata M. Yoshioka and S. Hirai J . Amer. Chem. Soc. 1972 94 4635. 1 4 3 ( a ) H. D. Visser and J. P. Oliver J . Organometallic Chem. 1972 40 7; (6) T. Kegawa and H. Hashimoto Bull. Chem. SOC. Japan 1972 45 1739; ( c ) K. Gosling and A. L. Bhuiyan Inorg. Nuclear Chem. Letters 1972,8 329; ( d ) J. D. Glore and E. P. Schram, Inorg. Chem. 1972 11 1532. 144 ( a ) S. Pacynkiewicz and K. Dowbar J. Organometallic Chem.1972,43 75; (b) B. Sen, G. L. White and J. D. Wander J.C.S. Dalton ( c ) M. Boleslawski and S. Pacynkiewicz, J. Organometallic Chem. 1972,43,8 1 ; (d) A. T. Weibel and J. P. Oliver J . Amer. Chem. SOC. 1972 94 8590; ( e ) T. Hirabayashi and Y . Ishii J . Organometallic Chem. 1972, 39 C85 208 D. W. A . Sharp M . G. H . Wallbridge and J. H. Holloway (R,AlX) + Ni(cod) -+ (R,AlX),Ni(cod) + cod (R = Me,X = SMe;R = Me,X = SPh; R = Et,X = PPh,; cod = cyclo-octadiene) However little experimental evidence is given for such a conclusion and further results are required.',,' Compounds containing Al-0 Bonds. In a continuing study of stereochemically non-rigid molecules the crystal structure of tris(tropolonato)aluminium(III) shows the ligands to be slightly bent in the vicinity of the metal atom but the most significant feature of the AlO co-ordination sphere is the 48.1" twist angle compared with 60" for a regular octahedron.For this molecule the non-rigidity possibly lies in the ground-state geometry of the complex and the distortion around the metal atom towards trigonal prismatic probably offers a relatively low-energy pathway to rearrangement through a twisting about the three-fold axis of the chelate molecule.145" Double isopropoxides M[M'(OPr'),] (M,M' = Al Ga or In) containing bridging alkoxy-groups between the metal atoms are volatile compounds which have been prepared by treating the anhydrous metal chloride of one metal with the potassium salt KM(OPr') of another metal.145b The use of 'H n.m.r. spectroscopy has shown that when AlI'' Ga"' or In"' ions are dissolved in trimethyl phosphite-water mixtures a total of six solvent molecules fill the first co-ordination sphere around the metal ion but that several species Al[P(OMe),],-,(H,O) are believed to co-exist in equilibrium in solution.14" Rapid ring-opening of THF occurs when triethylborane is added to Li[Al(OBu*),] yielding 1-butanol but in the absence of the boron alkyl no reaction Compounds containing Aluminium-Halogen Bonds. The existence of solvated halides MX (M = B Al or Ga) in acetonitrile has been established from 'H n.m.r. spectra; for BX and GaX the solvation number of one suggests the presence of [MX,(MeCN),] + MX,- species while for AlX the solution appears to contain [A1(M&N),]3 + [AlCl,-1 ions corresponding to a solvation number of 1S.146a Another study using "A1 n.m.r.spectra shows that all five mixed halide ions AlCl,Br,- (0 < n < 4) exist in equilibrium in acetonitrile solution!46b The solid-state structures of a series of 1 1 adducts between MCl (M = Al, Ga In or T1) and 2,2',2"-terpyridyl (terpy) show that the Al In and T. compounds form an isomorphous series and although their structures could not be unam-biguously determined from the i.r. spectra it does appear that the gallium complex 14' (a) E. L. Muetterties and L. J . Guggenberger J. Amer. Chem. SOC. 1972 94 8046; (b) A. Mehrotra and R. C. Mehrotra Inorg. Chem. 1972,11,2170; ( c ) J. Crea and S. F. Lincoln ibid. p. 1131 ; ( d ) H. C. Brown S. Krishnamurthy and R. A. Coleman J . Amer. Chem.SOC. 1972 94 1750. ' 4 6 (a) I . Y . Ahmed and C. D. Schmulbach Inorg. Chem. 1972,11,228; (b) D . E. H. Jones, J.C.S. Dalton 1972 567; (c) G. Beran K. Dymock H. A. Patel A. J. Carty and P. M. Boorman Inorg. Chem. 1972 11 896 The Typical Elements 209 has a distorted octahedral trans-configuration.' The crystal structures of Hg,(AlCl,) ,147a Te4(AlCl4), and Te4(A1,C17),'47b have been determined by X-ray methods ; the mercury compound contains discrete molecules having a nearly linear C1-Hg-Hg-Hg-C1 skeleton with the chlorine atoms being shared with two nearly tetrahedral AICl,- anions. The tellurium compounds contain square Te42+ ions and tetrahedral AlCl,- or Cl3A1-Cl-AIC1,- anions. The 1 1 adduct A1Cl3,S4N has been and an interesting study of the interaction of AlBr and All with graphite shows that unlike the chloride, AlBr reacts only if free bromine is also present and then a compound C,,AIBr,Bro, has been is01ated.l~~' The resistivity of a range of such compounds suggests that the bromine plays a large part in assisting charge-transfer processes.148c The concentration dependence of the specific conductivity of AlCl and LiAlH in tetrahydrofuran has been suggested to arise from the formation of AIHCl, AlH,Cl and the ionized complexes Li'AlHC1,- and LifAlH2C12-.149" A new dye Mordant Blue 31 has been found to be a satis-factory reagent for the fluorometric determination of aluminium and gallium since it forms 1 1 complexes with these metals in acidic solution.'49b Although the possibility of any A1-H-A1 species is not discussed another study shows that when associated compounds such as Bu,'AlH and Bu,'AICl are mixed then signals arising from mixed complexes which may be either dimeric or trimeric, can be detected in the 'H n.m.r.spectra of mixtures of these two corn pound^.'^^^ Gallium and Indium-The investigations on these two elements follow a similar pattern to those in previous years. The halogeno-compounds and co-ordination chemistry continue to be of interest and compounds containing metal-carbon bonds also form the basis of many papers. Compounds containing Metal-Hydrogen Bonds. A series of cyclogallazanes [CH,-(CH,),-$+I-GaH,] (x = 1 2 3 or 4; n = 2 or 3) together with the analogous boron and aluminium compounds have been prepared by the action of the base on the Me,N,MH (M = B Al or Ga) compounds and the factors affecting the ring size in this series of compounds have been surnmari~ed.'~~" The details of the crystal structure of the aziridinylgallane trimer have been reported.' 50b Compounds containing Metal-Carbon and Metal-Halogen Bonds.The crystal structure of tris(cyclopentadienyl)indium(m) reveals that the molecule is arranged in infinite polymeric chains with each chain unit composed of an indium atom linked to two terminal a-bonded and two bridging cyclopentadienyl groups. 14' ( a ) R . D. Ellison H . A. Levy and K. W. Fung Inorg. Chem. 1972,11 833; ( 6 ) T. W. Couch D. A. Lokken and J . D. Corbett ibid. p. 357. 1 4 * ( a ) F. P. Olsen Inorg. Chem. 1972 11 2836; T. Sasa Y. Takahashi and T. Mukaibo, ( 6 ) Bull.Chem. Soc. Japan 1972,45 937; ( c ) ibid. p. 2657. 149 ( a ) M. Yoshio N. Ishibashi H. Waki and T. Seiyama J. Inorg. Nuclear Chem. 1972, 34 2439; ( b ) K. Hiraki Bull. Chem. Soc. Japan 1972 45 789; ( c ) J. J. Eisch and S. G. Rhee J . Organometallic Chem. 1972 38 C25. Is' ( a ) A. Storr B. S. Thomas and A. D. Penland J.C.S. Dalton 1972 326; ( b ) W. Harrison A. Storr and J . Trotter ibid. p. 1554 2 10 D. W. A . Sharp M . G. H. Wallbridge and J. H . Holloway These four groups give a slightly distorted tetrahedral environment around each metal atom and provide the first clear evidence for the existence of a bridging cyclopentadienyl group.' 5 1 a The crystal structures of the salts MInMe (M = Li, Na K Rb or Cs) also show a tetrahedral array of methyl groups around each indium atom and each alkali-metal cation is in turn surrounded by four methyl groups in a similar orientation.' ' A series of monomeric four-co-ordinate complexes (C6F,),In,L[L = C5H5N Ph3P Ph3P0 Ph3As0 or tmed (NNN'N'-tetramethylethylenediamine)] and five-co-ordinate complexes (C,F,),In,L, (L = Me,SO or THF) have been prepared and other complexes [(C,F,)In],L [L = bipyridyl or Ph,P(CH,),PPh,] together with the (C,F,),In(tmed) com-pounds are considered to contain bridging ligands with a four- and five-co-ordinate indium atom respectively.' l C The gallium halides Ga,X (X = C1 Br or I) react with primary secondary, and tertiary alkyl halides although the ease with which the various reactions proceed depends upon the combination of groups used.However typical compounds isolated include RGa,Br (R = Me or Et),15" MeGa,Cl,I and MeGa,Br,I.152b Gallium (and indium) metal will also react with RX compounds (R = Me or Et ; X = Br or I) at room temperature to yield R3Ga,X3 which may be considered as a mixture of R,GaX and RGaX .' 52c A series of indium com-pounds of empirical formula RInX (X = Br or I ; R = Me Et Pr or Bu) has been synthesized from the action of InBr and In1 with the corresponding alkyl halide, and spectroscopic evidence suggests that the bromo-compounds are probably polymeric while the iodides are best formulated as InMe,' InI,-.'52d The interaction of a series of R,InX or MeInC1 compounds with Me3SbS affords stibonium salts such as RMe3SbX (R = Me or Et ; X = C1 Br or I) and Me,SbCl respectively while with the trichloride InCl the intermediate 1 1 adduct (which contains an In-S bond) reacts further to produce Me3SbC1 .152e Dealkylation of indium alkyl compounds occurs on reaction with various ligands such as a-mononitroalkanes,' 5 2 f SSCNMe (dtc) 8-hydroxyquinoline (oxH) and HOC,H,NMe ' 52g and the corresponding dialkylindium compounds Et,In[C(NO,)R,] (R = H or Me) Me,In(dtc) MeIn(dtc) Et,In(ox) and R,InOC,H,NMe (R = Me or Et) are obtained.The hydrolysis of the Innr ion in solutions containing chloride ions is in fact concerned with ions such as InC12+ and InC12+,153a and following estimates of the [In3+] concentration as a function of [Cl-] it has been suggested that only a small part of the indium chloride complexes can be hydrolysed before the main l s l (a) F.W. B. Einstein M. M. Gilbert and D. G. Tuck Inorg. Chem. 1972 11 2832; ( 6 ) K. Hoffmann and E. Weiss J . Organometallic Chem. 1972,37 1 ; (c) G. B. Deacon and J. C. Parrott Austral. J . Chem. 1972 25 1169. I s 2 W. Lind and I. J. Worrall ( a ) J . Organometallic Chem. 1972 36 3 5 ; ( 6 ) ibid. p. 35; M . J. S. Gynane L. G. Waterworth and I. J . Worrall ( c ) ibid. p. C59; ( d ) ibid. p. 257; ( e ) T. Maeda G . Yoshida and R. Okawara ibid. l972,44,237;(f) L. M. Golubinskaya, V. I . Bregadze E. V. Bryuchova V. I . Svergun G. K. Semin and 0. Yu. Okhlobystin, ibid. 1972 40 275; ( g ) T. Maeda and R. Okawara ibid. 1972,39 87. 1 5 3 D. Ferri ( a ) Acfa Chem. Scand. 1972 26 733; ( 6 ) ibid. p. 747; ( c ) S. F. Lincoln A. Sandercock and D. R. Stranks J.C.S. Chem.Comm. 1972 1069; ( d ) H. A. Oye and W. Bues Inorg. Nuclear Chem. Letters 1972 8 31 The Typical Elements 21 1 product of hydrolysis In2C10H4+ is pre~ipitated.’’~~ The rate parameters of the exchange of a C1- ion on GaC1,- in concentrated hydrochloric acid have been obtained from ,’Cl magnetic resonance results by following the broadening of the resonance absorption,153c and in addition to the GaC1,- and Ga,Cl,-ions the neutral dimer Ga,Cl has been identified in mixtures of CsCl and GaCl,.153d The I ~ I C ~ ~ - ion has been identified in the crystal structure of (MeNH,),InCI and in lower oxidation state indium compounds such as InBr and In,Br the ionic formulations In+ (InBr4-) and 2(1n+) In,Br,’-, respectively have been proposed from the Raman spectra of the solids.154b Force-constant calculations have been made on several anionic In’ and In”’ halide complexes namely InX,,- (X = C1 Br or I) InX,- (X = C1 Br or I), InCl,,- and InCl, - and for the In”’ chloro-anions the constant decreases linearly with increasing co-ordination number.Significant ionic character in the In-X bonds is suggested from the way in which the constant varies with the electronegativity of the ligand the co-ordination number and oxidation state of the metal When gallium trichloride reacts with S,O,F or BrOS0,F the tris-fluorosulphate Ga(SO,F) is obtained and the i.r. spectrum suggests that the compound is polymeric containing bridging bidentate fluorosulphate groups about a six-co-ordinate metal atom.’” The crystal structure of GaCI,,-bipy (bipy = 2,2’-bipyridyl) shows the presence of the [cis-Cl,Ga(bipy),]+ GaC1,- ions,’ and the first hydroxo-bridged octahedral gallium chloride complex (26) which has been characterized from X-ray data is formed in the attempted preparation of GaCI,(MeMe’dpma) [MeMe’dpma = methyL(6-methyl-2-pyridylmethyl)(2-pyridylmethyl)amine] when the reaction solution is hydrolysed by moist acetonitrile.In the absence of moisture a different complex is obtained which is formulated as [GaCI,(MeMe’dpma)]+ GaC1,- or [GaCl,-(MeMe’dpma)] [GaCl,] and with InCl or TICl the non-ionic compounds MCl,(MeMe’dpma) are The formation of 1 1 adducts between M’’(saen) [saen = NN’-ethylenebis(salicy1ideneaminato) ; M = Co Ni or Cu] and InX (X = C1 or Br) has been reported and although the planarity about M is preserved in the complex the question of whether M is five-co-ordinate or not could not be res~lved.’’~~ Compounds containing Gallium (and Indium)-Transition Metal Bonds and Mis-cellaneous Studies.The red crystalline compound Ga,[Mn(CO),] has been prepared by heating gallium metal with Mn,(CO), in a sealed tube at 413 K, and i.r. and Raman studies indicate the presence of a Mn-Ga-Ga-Mn, skeleton but for the In[Mn(CO),] compound prepared similarly the framework ( a ) H. Schlimper and M . L. Ziegler Z . Naturforsch. 1972,27b 377; ( b ) L. Waterworth and I . J. Worrall Inorg. Nuclear Chem. Letters. 1972 8 123; (c) J. G. Contreras and D. G . Tuck Inorg. Chem. 1972 11 2967. I s 5 A. Storr P. A. Yeats and F. Aubke Canad. J. Chem. 1972 50 452. 1 5 6 ( a ) R.Restivo and G. J. Palenik J.C.S. Dalton 1972 341; (b) K. Dymock G. J. Palenik and A. J. Carty J.C.S. Chem. Comm. 1972 1218; ( c ) M. D. Hobday and T. D. Smith J.C.S. Dalton 1972 2287 212 D. W. A . Sharp M. G. H. Wallbridge and J . H. Holloway Me uCH2 / .Me (26) consists of a planar InMn skeleton.'57a The In-Mn bonds in In[Mn(CO),], are easily cleaved by halogens or hydrogen halides to form the halogeno-deriva-tives X -,In[Mn(CO),] (X = C1 or Br ; n = 1 or 2) and while these compounds undergo disproportionation reactions in acetone or methanol to yield In[Mn(CO),] and InX, in acetonitrile they are converted into the [(MeCN),-InMn,(CO),,] + cation.' 5 7 b A general method for preparing transition metal-indium bonds has been devised as typified by the example '' 3Naf[C,H,(CO),Mo]- + InCl -+ In[Mo(CO),C,H,] + 3NaCl The formation constants for a series of mixed metal complexes between In"' and U'" with malic tartaric and citric acids have been determined and for the first two acids the equilibrium can be written as U022+ + In3+ + 2 H 3 L e UO,InL,- + 6H+ the logarithms of the equilibrium constants being - 7.62 and -7.14 for the malate and tartrate systems respectively.For citric acid the equilibrium is UOZ2+ + In3+ + 2H4L~U0,1nL,3- + SH' where two of the protons arise from the hydroxy-groups of the ligand. It is worthwhile noting that there is only limited information available on mixed metal systems compared with that published on mixed ligand systems.' 5 8 n Stability constants have been determined using conventional potentiometric techniques for the interaction of In'" with RCOCH,COCF (R = 2-furyl 2-thienyl C,H, 2-naphthyl Bu' or and the polarographic behaviour of In"' in several nitrates has been examined ; the results have been interpreted with respect to viscosity diffusion coefficients and ionic solvation parameters.58c The crystal structure of Bi,In4S9 has been determined the sulphur atoms forming a close-packed arrangement with three indium atoms being octahedrally surrounded by sulphur atoms and the fourth indium atom being in a distorted tetrahedron of sulphur atoms. The six- and seven-co-ordination of the two bismuth atoms by sulphur is related to the co-ordination in Bi2S .159 15' ( a ) H. J . Haupt and F. Neumann Z . anorg. Chem. 1972 394 67; A. T. T.Hsieh and M . J . Mays (b) J.C.S. Dalton 1972 516; ( c ) J . Organometallic Chem. 1972 37 9. ( a ) G. Markovits P. Klotz and L. Newman Inorg. Chem. 1972 11 2405; (6) K. Bowden G. M. Tanner and D. G. Tuck Canad. J . Chem. 1972 50 2622; ( c ) P. S. Jain and S. Lal Monarsh 1972 103 751. I s 9 G . Chapius C. Gnehm and V. Kramer Acta Cryst. 1972 B28 3128 The TypicaI Elements 213 Thallium-The 2o 5Tl-'H spin-spin coupling constants have been measured for a series of arylthallium dichlorides and while they are similar to the 'H-IH constants in benzenes they are of course much larger and therefore easier to measure.' 60a A number of aryl(chloromethy1)thallium chlorides Ar(ClCH,)TlCl (Ar = C6H5 or p-Me*C&) have been prepared by the action of diazomethane on ArTlCI compounds,'60b and complexes Of C6H5TlC12 with several terdentate (with ON0 and ONS as ligand atoms) and quadridentate ligands (with ONNO as ligand atoms) have been characterized.'60' The crystal structure of TlCl ,-(1,lO-phenanthroline) shows the metal atom to be in a distorted octahedral environment the basal plane being formed by the ligand and two chlorine atoms with another two chlorine atoms at the apices the whole molecule existing as a weakly bonded dimeric species.' 60d In the structure of salicylato-( 1,lO-phen-anthroline)thallium(I) shown schematically in (27) the two halves of the dimeric molecule are related by a two-fold axis while the five atoms in the metal co-ordination sphere form the base of a shallow irregular pentagonal pyramid which has the metal atom at its apex.161Q Another series of Tl' compkes has been prepared by dissolving TlL compounds (themselves prepared by dissolving TlOH in HL) in the acid HL where L is a potential bidentate ligand such as 8-hydroxyquinoline 2-ni trophenol or 2-hydroxybenzoic acid and in comparison with similar potassium complexes the thallium compounds are rather more stable.I6 l b The thallium(1) hexafluorogermanate Tl,GeF6 prepared from the action of a Ge0,-HF mixture on thallium(:) acetate has a similar structure to K2GeF6,l6," and other structure determinations on T10F'62b and T1F,'62' show that the former is related to the fluorite structure but with thallium atoms in the distorted eight-fold co-ordination site while in the latter each metal atom has eight nearest neighbours arranged in a distorted trigonal prism with two fluorine atoms above the side faces of the prism.The kinetics of the reduction of Tl"' ions by As"' ions in aqueous perchloric acid forming T1' and As" ions have been recorded; the reactive species are T10H2 + and HAsO .163a The photolytic destruction of luminescence of T1' solutions containing chloride ions has been found to be caused by an oxidation process T1' + 2H+ + 0 +T1"' + H,O, for which the presence of chloride ions is necessary. ' 63b 160 (a) J . P. Maher M. Evans and M. Harrison J.C.S. Dalton 1972 188; (b) T. Abe and R. Okawara J. Organometallic Chem. 1972,43 117; ( c ) L. Pellerito R. Cefalu and G. Ruisi ibid. 1972 44 243; (4 W. J . Baxter and G. Gafner Inorg. Chem. 1972 11 176. 16' (a) D.L. Hughes and M. R. Truter J.C.S. Dalton 1972 2214; (b) N. S. Poonia and M. R. Truter ibid. p. 1791. 16' ( a ) B. Hajek and F. Benda Cull. Czech. Chem. Comm. 1972 37 2534; (b) M. Vlasse, J. Grannec and J. Portier Acta Cryst. 1972 B28 3426; (c) C. H. Hebecker Z . anorg. Chem. 1972,393 223. 1 6 3 (a) P. D. Sharma and V. K. Gupta J.C.S. Dalton 1972 52; (b) G. F. Kirkbright P. J. Mayne and T. S. West ibid. p. 19 18 214 D. W. A . Sharp M. G. H . Wallbridge and J. H . Holloway >-0 / N \ / - 5 PART II Groups IV and V 1 GroupIV Carbon.-A considerable amount of work continues to be carried out on graphite intercalation compounds and the compounds with alkali metals have been reviewed.'" Amongst substances that can be intercalated into graphite are mixed halogens (iodine is inactive on its own but is intercalated in the presence of other halogens") hydrogen fluoride," and hexachloroplatinic acid (PtCl is inactive).lc The intercalates between tripositive halides and graphite are good metallic conductors comparable with nickel or iron.ld Intercalation compounds of the alkali metals show possibility for their purification ;le graphite-potassium is an active catalyst for deuterium-paraffin exchange ;lJ the graphite-FeC1,-K system exhibits high catalytic activity for the synthesis of ammonia,Ig and the graphite-PdC1,-Na system forms dimethyl ether from hydrogen and carbon monoxide.lh Methyl and ethyl hexafluoroantimonates and their SbF adducts are stable in SbF,-S02 or SbF,-SO,ClF solutions at low temperatures. There appears to be a fluorine bridge between the alkyl group and antimony and even at 150 K there is rapid alkyl-group exchange.2 The detailed structures of several carbonium ions are now known ; in azidoformamidium chloride [(H,N),CN,]Cl the (H,N),C (a) Y.N. Novikov and M. E. Vol'pin Run. Chem. Rev. 1971 9 733; (6) G. Furdin and A. Herold Bull. SOC. chim. France 1972 1768 3345; ( c ) A. A. Opaloroskii A. S. Nazarov and A. A. Uminskii Russ. J. Inorg. Chem. 1972 17 632; A. Boeck and W. Rudorff Z. anorg. Chem. 1972 392 236; (6) B. Bach and A. R. Ubbelohde J. Chem. SOC. ( A ) 1971 3669; ( e ) D. Billaud and A. Herold Bull. SOC. chim. France, 1972 103; (f) M. Ichikawa K. Kawase and K. Tamaru J.C.S. Chem. Comm. 1972, 177; ( g ) M. Ichikawa T. Kondo K. Kawase M. Sudo T.Onishi and K. Tamaru, ibid. p. 176; ( h ) S. Naito 0. Ogawa M. Ichikawa and K. Tamaru ibid. p. 1266. J. Bacon and R. J. Gillespie J. Amer. Chem. SOC. 1971 93 6914 The Typical Elements 215 and N parts of the cation belong to almost independent n-bonding system^.^ Simultaneous deposition of beams of lithium and methyl halides gives halogeno-methyl radicals (e.g. CH,Br') ; the radicals appear to have nearly planar ge~metries.~ The carbanion in Li(Me,NCH,CH,NMe,)CPh does not quite have a planar arrangement about the central carbon atom but there appears to be interaction between the lithium and one phenyl ring," and similar interaction is found in other lithium derivatives of car bani on^.^' The anions in dinitromethanides are generally planar about the central carbon atom but the nitro-groups are some-times propeller-shaped [in K NCC(NO,),]S' and sometimes twisted asymmetric-ally [in Rb NCC(N02)2Sd and K P-C~C~H~C(NO,),].~~ Rb2(02N)2C2(N02)2 has a slightly distorted anion because of steric effects but the arrangement about each carbon atom is still planar.'/ There continues to be a considerable interest in pseudohalogen derivatives related to cyanides.The hydrolysis of cyanide ion in aqueous solution involves attack of OH- on HCN.6" Cyanogen azide is an explosive oil obtained from sodium azide and cyanogen chloride in anhydrous media ; it undergoes an exten-sive series of organic reactions.6b Azodicarbonitrile NCNzNCN is best formed from cyanogen chloride hydrazine hydrate and sodium a ~ i d e . ~ " It is an orange-red solid with a trans c~nfiguration.~' The microwave spectrum of ClNCO confirms that it is an isocyanate ; it is a planar bent molecule and the isocyanate group is bent at carbon away from the chlorine.8" Me,SiNCO and Me,CNCO appear to have linear MNCO chains8' (see also pp.225 and 244). Bromine isocyan-ate briefly reported last year,8c may be prepared by heating tribromoisocyanate.8d The (SCN) - ion is formed transitorily on oxidizing NH,SCN in acetonitrile.' Methyl allophanate is observed in its stable diprotonated form [isomers of H,N=C(OH)*NH=C(OH)OMe] in FSO,H-SbF,-SO,. l o Trichloroyethyl isocyanide dichloride Cl,CN=CCI, reacts with HCl-SbC15 to give CI,CN(H)= CCl SbCl,- which eliminates HCl to give the formamidium salt Cl,CN= CCl,SbCl .' l a Enamines react with inorganic halides to give organometallic derivatives e.g.SiC1 + H,C=C(NMe,)Ph base Cl,SiCH=C(NMe,)Ph in a + + 3 4 5 6 7 8 9 10 1 1 H . Henke and H. Barnighausen Acta Cryst. 1972 B28 1100. D. W. Smith and L. Andrews J . Chem. Phys. 1971 55 5295;'J. I. Raymond and L. Andrews J . Phys. Chem. 1971 75 3235. ( a ) J. J. Brooks and G. D. Stucky J . Amer. Chem. SOC. 1972,94,7333; ( b ) J. J. Brooks, W. Rhine and G. D. Stucky ibid. pp. 7339 7346; (c) B. Klewe Acta Chem. Scand., 1972 26 1921 ; (6) H. J. Bjernstad and B. Klewe ibid. p. 1874; ( e ) B. Klewe and S. Ramsoy ibid. p. 1058; (f) B. Klewe ibid. p. 1049. ( a ) G. H. Wiegand and M. Tremelling J . Org. Chem. 1972,37 914; ( b ) F. D. Marsh, ibid. p. 2966. ( a ) B. Bak R. Eskildsen and P. Jansen Acta Chem.Scand. 1971,25 3181; ( b ) B. Bak and P. Jansen J . Mol. Structure 1972 11 25. ( a ) W. H. Hocking and M. C. L. Gerry J . Mol. Spectroscopy 1972 42 547; ( b ) A. J . Careless M. C. Green and H. W. Kroto Chem. Phys. Letters 1972 16 414; M. Winewasser ibid. 1971 11 515; ( c ) D. W. A. Sharp M. G. H. Wallbridge and J. H. Holloway Ann. Reports 1971 68 A 295; (d) W. Gottardi Monatsh. 1972,103 1150. G. Cauquis and G. Pierre Bull. SOC. chim. France 1972 2244. G . A. Olah A. T. Ku and J. A. Olah J . Org. Chem. 1971,36 3582. ( a ) A. Schmidt Chem. Ber. 1972 105 3050; ( 6 ) H. Weingarten and J. S. Wager, Synth. Znorg. Metal-org. Chem. 1971 1 123 216 D. W. A . Sharp M. G. H . Wallbridge and J. H. Holloway general reaction which should be capable of much extension; amidium salts e.g.CI,GeCMe,C(NMe,) C1- are formed as intermediates. ' ' Dimethylcarbodi-imide MeNCNMe is prepared by desulphurizing NN'-dimethylthiourea with mercury(r1) oxide ; it undergoes spontaneous cyclic trimerization to hexamethyl-isomelamine.' Carbodi-imide derivatives e.g. R,Si(NCNPh) are readily formed from the corresponding cyanamide e.g. PhNCNH and the appropriate halide ;' 2 b N ?'-dicyclohexylcarbodi-imide can be alkylated to a carbodi-imidium cation R 'R2N=C=NR'. ' 2c Trifluoromethylsulphenyl chloride CF,SCI reacts with cyanamides by HCl elimination and addition to the multiple bond to give, for example (CF,S),NC(Cl)=NSCF from H,NCN ; cyanides are formed on heating e.g. CF,SN(Me)C(Cl)NSCF gives CF,SN(Me)CN and these can be hydrolysed to substituted ureas.', Alkyl carbamates in strong acid solutions at low temperatures are exclusively 0-protonated although rearrangements to N-protonated species occur on warm-ing.14 Methyl hydrogen carbonate MeHCO, is formed by the reaction of Na[MeOCO,] (from NaOMe and CO in methanol) with hydrogen chloride.' 5a Silyl-carbamates -carbonates and -thiocarbonates e.g. R,NC(O)OSiMe, are prepared from salts and the chlorosilane ;' '' bis(sily1)carbonates result when silanes react with carbonates in the presence of nickel catalysts.' 5 c Polymeric cyanodithioformic acid [NCCS( SH)] is formed on acidification of the sodium salt ;16a trimeric [HCS(SH)] is formed similarly from KHCS but the monomer and dimer are present in the gas phase and in chlorocarbon Esters [HCS(SR)] are formed from the potassium salt and alkyl iodides; they interact with thiols to give orthoesters HC(SR) .I6' Chloroform and potassium sulphide react to give the dithioformate KHCS ; other salts have been prepared from the free acid and alkoxides.'6d A platinum derivative of a fluorodithioformic acid, [(Ph,P),PtS,CF]+[HF,]- is formed by CS insertion into a Pt-F bond.16e Lithium trithiocarbonate Li,CS3 is best formed from butyl-lithium and the free acid.'' Spectroscopic studies on carbon monoxide in inert matrices suggest the presence of aggregates of CO molecules. Carbon atoms and carbon-containing molecules can react in matrices to give new species. Photolysis of l 2 ( a ) G. Rapi G. Sbrana and N. Gelsomini J . Chem. SOC. (0 1971 3827; ( 6 ) H. Kohler and H.V. Dohler Z . anorg. Chem. 1971 386 197; (c) R. Scheffold and E. Saladin Angew. Chem. Internat. Edn. 1972 11 229. l 3 A. Haas and V. Plass Chem. Ber. 1972 105 2047. l 4 G. A. Olah A. M. White and A. T. Ku J . Org. Chem. 1971 36 3585. I s ( a ) G. Gattow and W. Behrendt Angew. Chem. Internat. Edn. 1972 11 534; (b) Y. Yamamoto and D. S. Tarbell J . Org. Chem. 1971 36 2954; L. Birkofer and P. Sommer J . Organometallic Chem. 1972 35 C15; (c) M. Paul J. Dunogues R. Calas, and E. Frainnet ibid. 1972 38 267. I b ( a ) R. Engler and G. Gattow Z . anorg. Chem. 1972 390 73; ( 6 ) R. Engler and G. Gattow ibid. 1972 389 145; ( c ) R. Engler G. Gattow and M. Drager ibid. 1972, 390,64; (d) R. Engler G. Gattow and M. Drager ibid. 1972,388,229; ( e ) J. A. Evans, M. J. Hacker R.D. W. Kemmitt D. R. Russell and J. Stocks J.C.S. Chem. Comm., 1972 72. H. Seidel and R. Meyn Z . Narurforsch. 1971 26b 1192. ( a ) J . B. Davies and H. E. Hallam J.C.S. Faraday I I 1972 509; ( 6 ) R. L. deKock and W. Weltner jun. J . Amer. Chem. SOC. 1971 93 7106 The Typical Elements 217 C302 gives CCO and CCCO and CNN is formed on trapping carbon atoms in a pure nitrogen matrix.'8b There is continued interest in the lower carbon fluorides and a new static-bomb synthe~is'~" of C,F and a fluorine-plasma synthe~is'~' of (CF) have been described these materials have a high potential for use as lubricants and as cathode materials. Carbonyl fluoride has shown itself to be a good reagent for converting SiOR groups into SiF." The formation of several perfluoro-deriva-tives of azodiformamidine has been described.(NF,),CFN=NCF(NF,) and (NF,),CFN=NC(=NF)NF react with carbon monoxide to give FN=CFN= NCF=NF and FN=CFN=NC(=NF)NF respectively. The reaction of (NF,),CFN=NC(=NF)NF with ammonia followed by fluorination gives (NF,),CN=NCF(NF,) ; the reaction with lithium amide gives the formamidine (NF,),CFN=NC(=NF)NH . lo LiN=C(CF,) substitutes the ketimidegroups for halide in many metal derivatives. Carbonyl derivatives undergo rearrange-ments to give (CF,),C(F)NCO and (CF,),C=NC(CF,),NCO and there are similar rearrangements to -NSO derivatives after reactions with thionyl halides.,lb CF,OOF may be conveniently prepared by fluorinating CF,CO,H in the presence of caesium fluoride,," or from COF and 0,F in the presence of CsF.,,' FC(O)OOC(O)F isomerizes to the ozonide of the unknown difluoro-ketone F2C /O\C = 0 ; strong bases catalyse its diproportionation to \ I 0-0 (CF,OO),CO and CF300C(0)F.22' Very full details of studies on charge-transfer interactions between halides - including CX - and aromatic hydro-carbons and fluorocarbons have now been given.Silicon tetrachloride is an inert non-perturbing medium but most other high-oxidation-state halides show interactions.,, Silicon.-Silicon atoms react with silanes by insertion into Si-H bonds to give silylenes which either polymerize or insert into the Si-H bond of another molecule e.g. CH,SiH gives MeSiH,SiH 1,2-Me2Si,H4 1,3-Me2Si,H,, 1,2,3-Me3Si,H, and Me2Si,H6., Na,Si,, is formed by thermal decomposition of NaSi; between 590 and 720 K 3 < x < 11 ; it has a clathrate lattice with sodium atoms in a polyhedral lattice of silicon.25 l 9 ( a ) R.J. Lagow R. B. Badachhape P. Ficalora J. L. Wood and J . L. Margrave, Synth. Inorg. Metal-org. Chem. 1972,2 145; (6) R. J. Lagow L. R. Shimp D. K. Lam, and R. F. Baddour Inorg. Chem. 1972,11,2568. 2 o R. Muller and D. Mross 2. Chem. 1971 11 382. 2 1 ( a ) J. B. Hynes T. E. Austin and L. A. Bigelow Inorg. Chem. 1972 11 418; (b) R. F. Swindell D . P. Babb T. J. Ouellette and J. M. Shreeve ibid. p. 242. 2 2 (a) D. D. DesMarteau Inorg. Chem. 1972,11 193; ( b ) I. J. Solomon A. J. Kacmarek, W. K. Sumida and J. K. Raney ibid. p. 195; (c) D. Pilipovich C. J. Schack and R. D. Wilson ibid. p. 2531. 23 L. A. Burkhardt P. R. Hammond R. H. Knipe and R.R. Lake J . Chem. SOC. ( A ) , 1971 3789 and following papers. 2 4 P. S. Skell and P. W. Owen J . Amer. Chem. SOC. 1972 94 5434. 2 5 C. Cros and J.-C. Benejat Bull. SOC. chim. France 1972 1739 218 D. W. A . Sharp M. G. H. Wallbridge and J. H. Holloway Silyl bromide reacts with PF,NH to give H3SiNHPF2 ; there are two con-formers present both with PF . . - HN interactions; that present in greatest abundance also has an SiH - FP interaction.26" Various chlorosilylamines, e.g. SiHCl,NHEt have been described as resulting from the reaction between amines and chlorosilanes.26b The formation of silyl-phosphines and -arsines from complex phosphidoaluminates and halogenosilanes has been previously de-scribed,27a and new examples of this reaction to produce Si-PH and Si-PHMe compounds are now Silylphosphine H,SiPH, is best prepared from SiH and PH in the presence of traces of iodine.27C Trisilylamine undergoes a trans-silylation reaction with H2Y (Y = S or Se) to form (H3Si),Y and also salts NH,+(YSiH,)-.The salts react with halides to eliminate ammonium halides, e.g. GeH,Br gives GeH,SSiH which disproportionates to (GeH,),S and (SiH,)2S.28 Phosphorus pentafluoride is a good reagent for converting Si-H into Si-F ;29a halogeno-disilanes and -trisilanes are formed by the action of a silent electric discharge on halogenomonosilanes or by halogenation of trisilanes with BCl or BBr,.29b Direct halogenation of silanes in the absence of solvent is an efficient method of producing bromo-silanes and -germanestgC and iodosilanes.9d Bis(trimethylsily1)mercurials (and the germyl derivatives) react with alkoxides R,MOMe to give unsymmetrical mercurials e.g. Me,SiHgSnMe Several methods are now available for the synthesis of polysilanes. Hexa-alkyldisilanes are formed from chlorosilanes and lithium in hexamethylpho~phoramide,~ I" and sodium-potassium alloy is an effective coupling agent for forming cyclic and cage p~lysilanes.~ I b Halogen can be substituted for methyl in permethylated cyclo-polysilanes by chlorodemethylation with HCl in the presence of AlCl ; some ring contraction also occurs. IC Disilanes undergo symmetrization on heating at 500 K or in the presence of alkoxides e.g. Pr"Me,SiSiMs =(Me,Si) + (Pr"Me,Si) . I d Rearrangements in cyclopolysilanes on irradiation appear to proceed through silylene extrusion ; 1,2,3-trisilacycloheptane derivatives (28) 2 6 ( a ) D .E. J. Arnold E. A. V. Ebsworth H. F. Jessep and D. W. H. Rankin J.C.S. Dalton 1972 1681 ; (6) J. E. Drake and N . P. C. Westwood J . Chem. SOC. ( A ) 1971, 3617. 2' ( a ) D . W. A. Sharp M. G. H. Wallbridge and J. H. Holloway Ann. Reports 1970, 67 A 289; ( 6 ) G. Fritz and H. Schafer Z . anorg. Chem. 1971 385 243; (c) I. H. Sabherwal and A. B. Burg Inorg. Nuclear Chem. Letters 1972 8 27. 2 8 S. Cradock E. A. V. Ebsworth and H. F. Jessep J.C.S. Dalton 1972 359. 29 ( a ) M. A. Finch L. H. Marcus C. Smirnoff C. H. van Dyke and N . Viswanathan, Synth. Inorg. Metal-org. Chem. 1971 1 103; E. W. Kifer and C. H. Van Dyke lnorg. Chem. 1972,11,404; ( 6 ) J. E. Drake and N. P. C. Westwood J .Chem. SOC. ( A ) 1971, 3300; J. E. Drake N . Goddard and N. P. C. Westwood ibid. p. 3305; (c)T. C. Geisler, C. G. Cooper and A. D. Norman Inorg. Chem. 1972 11 1710; (d) F. FehCr B. Mostert A. G. Wronka and G. Betzen Monatsh. 1972,103,959. 30 T. N. Mitchell J . Organometallic Chem. 1972 38 17. 3 1 ( a ) H. Sakurai and A. Okada J . Organometallic Chem. 1972,36 C13; ( 6 ) R. West and A. Indriksons J . Amer. Chem. SOC. 1972,94,6110; E. Hengge and F. Lunzer Synth. Inorg. Metal-org. Chem. 1972 2 93; (c) M. Ishikawa and M. Kumada ibid. 1971 1, 191; (d) H. Sakurai and A. Hosomi J . Organometallic Chem. 1972 36 C15; H. Sakurai and A. Okada ibid. 1972 35 C13 ( e ) H. Sakurai Y. Kobayashi and Y. Nakadaira J . Amer. Chem. SOC. 1971 93 5272; (f) H. Sakurai and M. Murakami, ibid.1972,94 5080; (g) H. L. Carrel1 and J. Donohue Acta Crysr. 1972 B28 1566 The Typical Elements 219 SiMe, SiMe, readily evolve ~ilylenes.~" Insertion of dimethylsilylene into an Si-H bond of a silacyclohexane occurs with retention of c~nfiguration.~'f Me,,Si has the flattened chair configuration of cyclohexane. lg An unstable species trapped from the gas-phase pyrolysis of 1,l-dimethyl-1-silacylobutane has been identified as Me,Si=CH containing a carbon-silicon double bond.32u The sila-alkene is also generated on thermal decomposition of (29).," A great deal of work has been published on the direct synthesis of carbosilanes by conventional condensation reactions e.g. MeSi(CH,SiMe,Br), reacts with lithium and CHBr to give MeSi(CH,SiMe,),CH.33" 1,3,5,7-Tetramethyltetrasila-adamantane Me4Si4(CH2) a product of the pyrolysis of Me4Si has full tetrahedral symmetry.33b The sila-adamantyl radical is readily formed and abstracts halogen from carbon tetra~hloride.~~' Si-C1 bonds in the adamantane are stable to hydrolysis ; LiNEt gives the silylamine which can be recovered from a solution in aqueous hydrochloric acid with the Si-N bond intact.33d Carbon vapour co-deposited with trimethylsilane gives various pro-ducts depending upon the carbon species ; the products include Me4% Me,Si(H.)-CH=CH2 (Me,Si),CH Me,SiCrCH and Me,SiCH=C=CHSiMe which can all be formed following initial insertion into Si-H bonds.34 Si-N bonds are converted into Si-C,F by photochemical reaction with hexafluoro-32 ( a ) T.J. Barton and C. L.McIntosh J.C.S. Chem. Comm. 1972 861 ; (6) T. J. Barton and E. Kline J . Organometallic Chem. 1972 42 C21. 3 3 ( a ) G. Fritz and G. Maass 2. anorg. Chem. 1971,386 163; G. Fritz and M. Hahnke, ibid. 1972 390 104 137 157 185 191; (b) E. W. Krahk R. Mattes K.-F. Tebbe, H. G. von Schnering and G. Fritz ibid. 1972 393 74; (c) G. D. Homer and L. H. Sommer J.C.S. Chem. Comm. 1972 1249; ( d ) C. L. Frye and J. M. Klosowski J. Amer. Chem. SOC. 1972,94 7186. 34 P. S. Skell and P. W. Owen J . Amer. Chem. SOC. 1972,94 1578 220 D. W. A . Sharp M . G. H . Wallbridge and J . H . Hollowuy benzene ;3 pentafluorophenyl-silanes and -germanes are also formed by the reaction between C6F5Br and a silicon%opper catalyst. 5 b N.m.r. spectroscopy has shown that silyl germyl and stannyl derivatives of cyclopentadiene indene, and 2,4-cycloheptadiene undergo rearrangements and exist in all possible isomers, e.g. (30 a - c ) ; 6a bis (t rimet hylgermy1)- and bis( t rime t hy 1stannyl)-cyclopentadien y 1s also undergo rearrangements (c$ p. 226).36b Although Ph3SnC7H7 in the solid has tin a-bonded to a seven-membered ring in the boat conformation with alternating C-C distances the molecule is fluxional in solution.36c Conjugation between two vinyl groups attached to the same silicon seems now to have been unequivocally demonstrated by photoelectron spectro~copy.~~ Crystal structure determinations on Me,M(CN) compounds (M = Si Ge, Sn or Pb) show increasing N . . - M interactions with the heavier elements ; the Si and Ge compounds are approximately tetrahedral molecules with only weak N .- M interaction but in the tin compound planar sheets are formed.38 Pre-parative details for many silazanes have been given the methods generally involving condensation reactions. Amongst the new derivatives are Cl,SiN(p, p’-SiC1,),NSiCl3 ;39a ring systems containing N-N links e.g. (31)39b [a ten-3 5 ( a ) J. M. Birchall R. N. Haszeldine M. J. Newlands P. H. Rolfe D. L. Scott A. E. Tipping and D. Ward J. Chem. SOC. ( A ) 1971 3760; ( b ) M. Weidenbruch and N. Wessal Chem. Ber. 1972 105 173. E. W. Abel and M. 0. Dunster J. Organometallic Chem. 197 1,33,161; G. I. Avramenko, N. M. Sergeyev and Y . A. Ustynyuk ibid. 1972,37,89; P. E. Rakita and G. A. Taylor, Inorg. Chem. 1972 11 2136; A. V. Kisin V. A. Korenevsky N. M. Sergeyev and Y.A. Ustynyuk J. Organometallic Chem. 1972 34 93; S. R. Stobart ibid. 1972 43, C26; M. D. Curtis and R. Fink ibid. 1972 38 299; C. H. Campbell and M. L. H. Green J. Chem. SOC. ( A ) 1971 3283; ( b ) Y. A. Ustynyuk A. V. Kisin and A. A. Zenkin J. Organometallic Chem. 1972,37,101; ( c ) J. E. Weidenborner R. B. Larrabee, and A. L. Bednowitz J. Amer. Chem. SOC. 1972,94,4140. U. Weidner and A. Schweig J. Organometallic Chem. 1972 37 C29; Angew. Chem. Internat. Edn. 1972 11 536. 3’ 3 8 J. Konnert D. Britton and Y. M. Chow Acta Cryst. 1972 B28 180. 3 9 ( a ) U. Wannagat H. Moretto and P. Schmidt Z. anorg. Chem. 1971 385 164; ( b ) U. Wannagat E. Bogusch and F. Rabet ibid. p. 261 ; U. Wannagat and S. Meier, ibid. 1972 392 179; U. Wannagat L. Gerschler and H.-J.Wismar Monatsh. 1971, 102 1834; (c) U. Wannagat and E. Bogusch ibid. p. 1806; U. Wannagat E. Bogusch, and P. Geymayer ibid. p. 1825; L. W. Breed and J. C. Wiley jun. Inorg. Chem., 1972 11 1634; ( d ) U. Wannagat E. Bogusch P. Geymayer and F. Rabet Monatsh., 1971 102 1844; 1. Haiduc and H. Gilman Synth. Inorg. Metal-org. Chem. 1971 1, 69 75; ( e ) D. Mootz J. Fayos and A. Zinnius Angew. Chem. Internat. Edn. 1972 11, 58 The Typical Elements Me2 Si MeN' \ I NMe 22 1 membered Si,N system rearranged to the Si,N4 cyclotetrasilazane system with two exocyclic amino-groups and ammonolysis of 1,3-dichlorotetramethyl-disilazanegave both Si,N and Si,N systems]. Derivatives withother than simple alkyl substituents are obtained by condensation or by subsequent reaction e.g.[Me,Si=NH] reacts with HX to give XSiMe2N(pp'SiMe,),NSiMe,X.39' Con-densation reactions with urea derivatives siloxanes or silanediols give ring sys-tems incorporating C and 0.39d It seems probable that the structures of some of these silazanes are more complex than has been assumed previously. The reaction of SiC1 and NaN(SiMed2 gives (32) which has a two-ring spiran SiMe SiMe, I I N N / \ . / \ Me,Si S1 SiMe, \ / \ / CH N I I SiMe SiMe, Enaminosilanes R,C=NSiMe,Cl,- (R = Bu'or Ph) are formed from R,C=NLi and the chlorosilane. The t-butyl derivatives appear to have linear CNSi skeletons whereas the phenyl derivatives may have a bent arrangement.,'" The olefins ( CF,)2C=C(CN)2 and CF,( CF,Cl)C=C( CN) undergo 174-addi tion with Si, Ge and Sn derivatives e.g.Me,SiSMe gives (CF,),C(SMe)C(CN)=C=N-SiMe ,40b N,O-bis(organosily1)-hydroxylamines RMe,SiNHOSiMe,R rearrange to the N,N-derivatives in the presence of base,41a whilst tris(organosily1)-hydroxylamines (R,Si),NOSiR rearrange on heating to silylaminosiloxanes R,SiN(R).SiR,-OSiR ,,lb and (33a) is in tautomeric equilibrium with (33b).,l' NN-Bis(organosily1)-hydroxylamines can be oxidized to nitroxide radicals by oxygen.41a Silyl azides e.g. Me,Si(N,) are readily formed from chlorosilanes ( a ) J . B. Farmer R. Snaith and K. Wade J.C.S. Dalton 1972 1501; E. W. Abel, J. P. Crow and J . N. Wingfield ibid. p. 787. ( a ) R. West and P. Boudjouk J . Amer. Chem. SOC. 1971 93 5901 ; ( 6 ) P. Boudjouk and R. West ibid. p. 5901 ; ( c ) B. Dejak and Z .Lasocki J . Organometallic Chem. 1972, 44. c 3 9 . 222 D. W. A . Sharp, CH,CON M. G. H. Wallbridge and J . H. Holloway and sodium azide in (Me,N),PO or HCONMe ;42a on photolysis trialkylsilyl azides give cycl~disilazanes.~~~ The product from the reaction between Me,SiN, and Fe,(C0)9 contains a Me,SiN group symmetrically bonded to three iron Silyltriazenes e.g. ArNNN(SiX,) are formed in reactions between triazenides and halogenosilanes or diazonium salts and bis(sily1)amides ; the silyl groups undergo migration throughout the nitrogen chain ;43a the tetrazene (Me,Si),N-N=N*N(H)SiMe is formed by hydrolysis of Me,SiN=NSiMe ; it decomposes thermally to an azide and a bi~(sily1)arnine.~~’ Although hexa-chlorodisilane undergoes disproportionation in the presence of amines in the presence of diphosphines and diarsines derivatives such as Me,AsSiCl are formed.44 Silicon monoxide behaves as a very reactive silylene and when condensed with organic compounds at low temperatures inserts into various bonds to give The methods of synthesis of a-difunctional oligosiloxanes have been critically and cyclocarbosiloxanes have been re~iewed.~” Silyl groups particularly the Me,Bu‘Si group appear to have great potential for the protection of hydroxy-groups ;46a silicones are formed during the thermal decomposition of bis(silyl)peroxides e.g.Ph,SiOOSiPh gives Ph,SiOSi(OPh)-Ph .46b Monomeric imino-oxysilanes e.g. Me,Si(ON CMe,) are readily formed by elimination reactions between chlorosilanes and ~ximes.~’ Bis-(trifluoromethyl)thioketen (CF,),C=C=S undergoes addition reactions with silanes and stannanes to form for example Et,SiSCH=C(CF,) .48 Studies of coupling constants in methylchlorosilyl radicals in solid matrices show that the structures of the radicals deviate more and more from planarity with the degree of substitution of methyl by chlorine.49 Studies on MeMX derivatives (M = Si, 4 2 ( a ) S .S . Washburne and W. R. Petersen jun. J . Organometallic Chem. 1971 33, 153 ; ( 6 ) D. W. Klein and J. W. Connolly ibid. p. 3 1 1 ; (c) B. L. Barnett and C. Kruger, Angew. Chem. Internat. Edn. 1971,10,910. ‘’ (a) N. Wiberg and H. J. Pracht Chem. Ber. 1972,105 1377 1388; ( b ) N . Wiberg and W. Uhlenbrock ibid. p. 63. 44 T. A. Banford and A. G. MacDiarmid Inorg. Nuclear Chem. Letters 1972,8 733.4 5 (a) E. T. Schaschel D . N . Grey and P. L. Tirnrns J. Organometallic Chem. 1972,35, 69; ( b ) M. G. Voronkov and N. G . Sviridova Russ. Chem. Rev. 1971 40 819; ( c ) N. S. Nametkin T. K. Islarnov L. E. Gusel’nikov and V. M. Vdovin ibid. 1972,41, 111. 46 ( a ) E. J . Corey and A. Venkateswarlu J. Amer. Chem. SOC. 1972 94 6190; ( b ) A. K. Shubber and R. L. Dannley J . Org. Chem. 1971,36 3784. 4 7 A. Singh A. K. Rai and R. C. Mehrotra J.C.S. Dalton 1972 191 1. 4 8 M. S. Raasch J. Org. Chem. 1972,37 1347. 4 9 C. Hesse N. Leray and J. Roncin J . Chem. Phys. 1972 57 749 The Typical Elements 223 Ge or Sn)give bond-energy termsE(C-X) -= E(Si-X) > E(Ge-X) > E(Sn-X) generally although E(C-Y) > E(Si-Y) for Y = H or Me. The softness (mea-sured in terms of AH) of the series Me,Mf increases in the order C < Si < Ge < Sn.” Although perfluoroalkylfluorosilanes have been mentioned previously, R,SiF are best prepared by fluorination of the R,SiF,I compounds which result from the reaction between R,I and SiF ;’ they decompose thermally by elision of fluorocarbenes.Tri-imidodisiloxane Si,O(NH) is formed by ammonolysis of Cl,SiOSiCl, at low temperatures; it decomposes thermally to the oxynitride Si,0N,.52 A large number of silatranes e.g. EtOSi(OCH,CH,),N with oxy substituents at the apical silicon atom have been described; the strength of the transannular N-Si bond is increased by the presence of an electron-withdrawing apical substituent. 53 Biguanide and guanylurea form stable cationic species with silicon.54 Silicon tetrafluoride undergoes ammonolysis or hydrolysis with amines or hydroxy-compounds ; fluorosilazanes or silicates can be isolated from the reaction mixtures but fluorosilicates are also formed. ’ ’ The dark green solid of stoicheiometry Cl,Si(bipy) formed by the action of Li,(bipy) on SiCl,,bipy appears to consist of two isomers (i) a hexaco-ordinate silicon compound Cl,Si(bipy) in both singlet and triplet states and (ii) a tetraco-ordinate silicon compound [Cl,Si(bipy)] [bipy]. In all cases the bipyridyl is present as radical anion^.'^" Complexes (py),SiCl,X and (py),SiCl,X and the corresponding o-phenanthroline derivatives have been prepared ; the structures are such that the larger halogen is out of the plane occupied by bulky ligands ; SiC1 groups are generally T shaped.56b One form of SiO, stishovite has the rutile structure and in this as in most other oxides with this structure two of the Si-0 distances are slightly longer than the other four (in CrO, RuO, and OsO this pattern is not f~llowed).’~ Zeolites with framework structures have large holes in which H,O NH, S8 rings in a crown configuration and acetylene can be present.’” The structures of crystals containing these sorbed molecules show them to be held by induced dipole forces.The rare-earth silicates M,0,,2Si02 contain chain Si,O Silicon catecholates and related derivatives e.g. (C,H,O,),Si and monomeric and dimeric C,H,O,SiCl, are formed from the diol and SiCl, J. C. Baldwin M. F. Lappert J. B. Pedley and J. S. Poland J.C.S. Dalton 1972 1943.K. G. Sharp and T. D. Coyle Inorg. Chem. 1972,11 1259. 5 2 P. Goursat D. Giraud and M. Billy Bull. SOC. chim. France 1972 3681. s3 C. L. Frye G. A. Vincent and W. A. Finzel J . Amer. Chem. SOC. 1971,93,6805. s 4 A. Maitra and D. Sen Inorg. Nuclear Chem. Letters 1972 8 793. s 5 d. J. Harris and B. Rudner J . Inorg. Nuclear Chem. 1972 34 75. 5 6 (a) P. M. Broudy A. D. Berry B. B. Wayland and A. G. MacDiarmid J . Amer. Chem. Soc. 1972,94 7577; (b) D. H. Boa1 and G. A. Ozin Cunad. J. Chem. 1972,50,2484. 5 7 W. H. Baur and A. A. Khan Actu Cryst. 1971 B27 2133. s8 ( a ) P. E. Riley K. Seff and D. P. Shoemaker J. Phys. Chem. 1972 76 2593; R. Y. Yanagida and K. Seff ibid. p. 2597; K . Seff ibid. p. 2601 ; A. A. Amaro and K. Seff, J.C.S. Chem. Comm. 1972 1201; (b) J.Felsche Naturwiss. 1972 59 3 5 . ” ( a ) H. R. Allcock T. A. Nugent and L. A. Smeltz Synth. Inorg. Metal-org. Chem. 1972, 2 97; (b) D . W. Barnum Inorg. Chem. 1972 11 1424; ( c ) G. Schott and D. Lange, Z . anorg. Chem. 1972,391,27 224 D. W. A . Sharp M. G. H . Wallbridge and J. H. Holloway triscatecholates often crystallize with an extra molecule of solvent and this is so firmly bound that it is probably co-ordinated to Oxalato derivatives, e.g. (R4N),Si(C204), (R,N),Ph,M(C,O,) (M = Si or Ge) are formed from chlorosilanes and silver oxalate and are very stable to hydrolysis ; compounds (R,N)RSi(C,O,) are very unstable to hydrolysis. 59c Alcoholysis of SiS gives (Bu'O),Si(SH) .60 Cd,SiS, like many other sulphides has SiS and CdS, tetrahedra linked by sharing corners ; the packing of sulphur atoms is strongly Na,Si,S, has adamantane-like Si,SIo4-Pt(Ph,P) reacts with silicon tetrafluoride to give (Ph,P),Pt.SiF which is suggested to contain a Pt-Si bond with five-co-ordinate silicon.62 What is probably an electronically excited form of SiF is produced when silicon tetra-fluoride is passed over silicon or silicon carbide at 1500-2230 K.With BF it gives SiF,BF in addition to known silicon boron fluoride^.^^" Co-condensation of SiF with B,H6 gives various silanes including H,SiSiF H,Si(SiF,),, HSi(SiF,) and Si(SiF,),. No silicon-boron compounds are isolated but the reducing conditions clearly lead to interesting SiF reacts with unsaturated compounds with formation of heterocyclic derivatives and insertion into bonds.Substrates that give reactions with SiF include fluoroalkenes buta-diene allene and acetylenes.63c Pyrolysis of chloro-silanes in the presence of acetylene gives products which whilst not precisely similar to those from reactions of SiF, suggest strongly that SiCI has been formed as an intermediate.63d From their e.s.r. spectra the radicals SiH,F SiHF, SiF, and Me,SiF all have pyramidal geometry about the silicon atom.64 Perchloropolysilanes form crystalline adducts with SiC1 ; in Si,Cl,,,SiCI the molecules of the two chloro-silanes are merely stacked together in the crystal.65 Finally the halogenosilane FClBrISi has been prepared by the procedure : h SiFBr SbC'3 b SiFClBr HS113 h SiFBrClI.66 SbF SiBr, Germanium.-GeX radicals are pyramidal and GeX species are bent when isolatedininert matrices.67 Thethreegermylpseudohalides,H,GeN ,H,GeNCO, and H,GeNCNGeH all have non-linear skeletons in the gas phase as is found h o W.Wojnowski and M. Wojnowska Z. anorg. Chem. 1972 389 302. 6 1 ( a ) B. Krebs and J. Mandt 2. anorg. Chem. 1972 388 193; A Cade M. Ribes E. Philippot and M. Maurin Compt. rend. 1972,214 C 1054. " T. R. Durkin and E. P. Schram Inorg. Chem. 1972 11 1042. 6 3 ( a ) D. L. Smith R. Kirk and P. L. Timms J.C.S. Chem. Comm. 1972 293; (b) D. Solan and A. B. Burg Inorg. Chem. 1972 11 1253; ( c ) A. Orlando C . S. Liu. and J . C. Thompson J. Fluorine Chem. 1972/3,2 103; J . C. Thompson and J. L. Margrave, Inorg. Chem. 1972,11,913; Y.-N. Tang G. P. Gennaro and Y. Y. Su J. Amer. Chem. SOC. 1972 94 4355; C. S. Liu and J .C. Thompson J. Organometallic Chem. 1972, 38,249; C. S. Liu J . L. Margrave J. C. Thompson and P. L. Timms Canad. J. Chem., 1972 50 459; C. S. Liu J. L. Margrave and J. C. Thompson ibid. p. 465; (d) E. A. Chernyshev N. G. Komalenkova and S. A. Bashkirova J. Gen. Chem. ( U . S . S . R . ) , 1971,41 1177. 6 4 M. V. Merritt and R. W. Fessenden J. Chem. Phys. 1972 56 2353. 6 5 D. K. Fleming Acta Cryst. 1972 B28 1233. 6 6 F. Hofler and W. Veigl Angew. Chem. internat. Edn. 1971 10 919. 6 7 G. R. Smith and W. A. Guillory J. Chem. Phys. 1972,56 1423; R. J . Isabel and W. A. Guillory ibid. 1972 57 1 1 16 The Typical Elements 225 for methyl analogues rather than for silyl species (cf p. 21 5).68" Halogenogermanes and lithium hydrazides give germylhydrazines including cyclic derivatives ; for derivatives of the type Me,NN(R)GeR the metalloid-nitrogen is basic and undergoes attack.68b Many germylarsines e.g.GeH ,AsMe and Me,Ge(AsMe,) , have been prepared by the reaction of aluminium and lithium arsenides or silyl-arsines with germanium halides.69 Specific methods for the preparation of monohalogenogermanes involve the use of thionyl chloride or boron tribromide with GeH4.70 Co-condensation of germanium or tin atoms with carbon monoxide into matrices at 20 K gives carbonyls probably GeCO and SnCO the first reported carbonyls for these element^.^ Generally a phenyl derivative of a non-metal hydride is more acidic than the parent hydride but the phenylgermanes constitute an exception to this rule. A possible explanation for the phenomenon lies in the lack of p-character in the germanium lone pair of for example the PhGeH,- ion and the consequent lack of pn-pn interaction between the phenyl group and the germanium.Permethylcyclopolygermanes can be prepared by coupling reactions using lithium or organometallic derivatives on halogenogermanes ; the polygermanes undergo redistribution reactions as do polysilanes. 73a Phenyl-halogenogermylenes insert into Ge-X bonds of phenylhalogenogermanes to give polygermane~.~~' Ge-X bonds add readily across double bonds to produce saturated derivatives. Examples described include addition to N=N N=O, and C=C.74a Addition of Me,MNMeM'Me (M,M' = Si Ge or Sn) to iso-cyanates or isothiocyanates gives varying products depending upon the affinity of M for 0 N or S and the tendency for the Me,M group to migrate.Tendencies for bond formation are Me3Si 0 > S 2 N Me,Ge S > 0 2 N; Me,Sn : S > 0 > N.74b Ph,GeOOH reacts with Et,Tl to give Ph,Ge00T1Et2; on heating the peroxide yields Et,TiOGePh,OPh and a similar derivative is formed if a silyl peroxide is used.75" 'Germyl sulphinates R ,Ge02SR2 are formed from the bromogermane and the appropriate silver Mass spectral studies on methylchlorogermanes suggest that there is a large decrease in the Ge-C1 bond strength with increase in the number of chlorine atoms present.76 " ( a ) J . D . Murdoch and D . W. H. Rankin J.C.S. Chem. Comm. 1972,748; L. K. Peter-son and K. I . The Canad. J . Chem. 1972,50 5 5 3 562. b9 J . W. Anderson and J . E. Drake J.C.S. Dalton 1972 951.7 0 J . W. Anderson and J. E. Drake Synth. Inorg. Metal-org. Chem. 1971 1 155; J. W. Anderson G . K. Barker J. E. Drake and R. T. Hemmings Canad. J . Chem. 1972, 50 1607. A. Bos J.C.S. Chem. Comm. 1972,26. 72 W. L. Jolly Inorg. Chem. 1971 10 2364. 7 3 ( a ) E. Carberry B. D. Dombeck and S. C. Cohen J . Organometallic Chem. 1972 36, 61 ; E. J . Bulten and J. G. Noltes Rec. Trav. chim. 1972 91 1041 ; ( 6 ) P. Riviere and J. Satge Synth. Znorg. Metal-org. Chem. 1971 1 13. 7 4 ( a ) K.-H. Linke H. J. Gohausen and G. Wrobel Chem. Ber. 1972,105 1780; J. Satge, M . Lesbre P. Riviere and S. Richelme J . Organometallic Chem. 1972 34 C18; J. Satge C. Couret and J . Escudie ibid. p. 83; ( b ) K. Itoh T. Katsuura I. Matsuda, and Y . Ishii ibid. p. 63. 7 5 ( a ) G.A. Razuvaev V. A. Dodonov T. I. Starostina and T. A. Ivanova J. Organo-metallic Chem. 1972 37 233; ( b ) E. Lindner and K. Schardt ibid. 1972,44 1 1 1 . 76 J. Tamas G. Czira A. K. Maltsev and 0. M. Nefedov J . Organometallic Chem., 1972,40 311 226 D. W. A . Sharp M. G. H. Wallbridge and J. H. Holloway Dichloro(phthalocyanino)germanium(Iv) is reduced by sodium borohydride to phthalocyaninogermanium(~~). GeCl,,NMe has trigonal-bipyramidal co-ordination about the germanium with nitrogen occupying an axial position.78 Clathrate-type compounds Ge,,M& (M = P As or Sb) are formed by heating the elements ; iodineatoms are present in cavities formed by the Ge-M skeleton.79 GeSb is formed in the Ge-Sb system ; it has a new structure type with an atomic configuration intermediate between those of Sb and Ge.80 but in the pH region 2-6 only mononuclear species Ge(OH),(4-")+ are present.81 Gd,Ge,O contains chain Ge,O and GeO groups.82u Magnesium germanate has the unit-cell composition Mg,8Ge,o0,8 .82b When magnesium fluoride is added and the material is grown from a PbF flux (a process which gives an efficient phosphor) structurally related Mg&e7.,O,,F,O is obtained.82c K,Ge(IO,) has a regular octahedral arrangement of oxygen about each ger-manium; each iodine group is in a very distorted octahedral c~nfiguration.~~ Thiolates [R,1N][R,2M(mnt)] [M = Ge Sn or Pb; R2 = Me or Ph; mnt = dicyanoethylene- 1,2-dithiolate] are formed from the halogenometallates and sodium thiolates ; with RMX derivatives bond cleavage occurs.84 Tin.-?-Irradiation of tin or lead salts gives Sn3+ and Pb3+ ions.85 In the vapour phase electron diffraction indicates only one form with gem-SnMe, groups for C,H,(SnMe,) (cf p.220).86 Hydride abstraction from positions B to carbon-metal bonds including tin is extremely facile and thus Ph,CBF, reacts with Me,SnEt with attack on the ethyl group to give Me,SnBF and ethylene.87 Dicyclopentadienyltin(I1) readily undergoes protolysis to tin(@ derivatives and many compounds that were previously inaccessible e.g. Sn(OMe) , Sn(OSiPh,) and Sn(SPh) may be prepared by this route.88 Co-ordination compounds between ethylenediamine and diaryltin dihalides are formed by direct interaction of the components spectroscopic studies Germanium(1v) at pH 0 to 2 exists as species Ge[Ge(OH)],'4+3")+ (n = 1-10), " R.L. Stover C. L. Thrall and R. D. Joyner Inorg. Chem. 1971,10,2335. " 7 9 H.-G. von Schnering and H. Menke Angew. Chem. Internat. Edn. 1972 11 43; H. M. S. Bilton and M. Webster J.C.S. Dalton 1972 722. Menke and H.-G. von Schnering Naturwiss. 1972,59 420. B. C. Giessen and C. Borromee-Gautier J . Solid State Chem. 1972 4 447. I. I . Alekseeva and I. I. Nemzer Russ. J. Inorg. Chem. 1971 16 987. ( a ) Y. I. Smolin Y. F. Shepelev and I . K. Butikova Sovier Phys. Cryst. 1972 16, 790; (b) D. W. A. Sharp M. G. H. Wallbridge and J. H. HLlloway Ann. Reports, 1971 68 B 309; ( c ) P. W. Bless R. B. von Dreele E. Kosher and R. E. Hughes, J . Solid Stute Chem. 1972,4 262. 8 3 F. Schellhaas H. Hartl and R. Frydrych Acra Cryst. 1972 B28 2834.8 4 E. S. Bretschneider and C. A. Allen. J . Organometallic Chem. 1972,38,43. 8 5 R. J. Booth H. C. Starkie and M. C. R. Symons J . Phys. Chem. 1972 76 141. 8 6 N. N. Veniaminov Y. A. Ustynyuk N. V. Alekseev I. A. Ronova and Yu. T. Struch-kov J. Struct. Chem. 1971 12 879. 8 7 J . M. Jerkunica and T. G. Traylor J. Amer. Chem. SOC. 1971,93 6278. P. G. Harrison J.C.S. Chem. Comm. 1972 544. 89 ( a ) T. N. Srivastava and K. L. Saxena J . Inurg. Nuclear Chem. 1971 33 3996; (6) J. C. May and C. Curran J . Organometallic Chem. 1972 39 289; ( c ) G.-E. Matsu-bayashi M. Hiroshima and T. Tanaka J. Inorg. Nuclear Chem. 1971,33 3787 The Typical Elements 227 suggest that terpyridyl complexes of R,Sn(NCS) have seven-co-ordination about tin with axial C-Sn-C bonds.*” Picolinamide and related ligands bond to the tin of Me,SnCl through the ring nitrogen and carbonyl oxygen (the ligand is either chelating or bridging); the thioamides only bond through the ring nitrogen.89c Aminophenols and related compounds react with dialkyltin oxides to give species of the type R2Sn(o-H2NC6H40)(OH) with chelated amino-phenolate ;’& a stannatrane PhSn(OCH,CH,),N is formed from [PhSn(O)OH], and triethanolamine ; there appears to be an N -+ Sn bond.’Ob [NN’-ethylenebis-(salicylideneiminato)]dimethyltin(~v) has a trans-octahedral co-ordination about tin with co-ordination from oxygen and nitrogen of the Schiff’s base;’” com-plexes of uncharged Schiff’s bases R,SnCl ligand are suggested to have weak co-ordination from nitrogen.’ I b There is considerable interest in organotin azoles.Tin triazoles and tetrazoles are formed by cycloaddition of a tin azide to alkynes or nitriles or by condensation of triazoles or tetrazoles with tin oxides or hydroxides triorganotin azoles are considered to have bridging azole groups and five-co-ordinate tin.’,’ Tributylstannyldiphenylmethyleneamine, Bu,SnN=CPh reacts with multiple bonds in cyanates ketones nitriles, sulphur oxides etc. to give stannyl derivatives e.g. Bu,SnOC(S)N=CPh from OCS.93” Stannyliminosulphuranes e.g. Me S(NSnMe,) are formed from the di-imide and chlorostannanes or by transamidation ; the tin iminosulphuranes undergo insertion reactions with CO for example.’,’ Organotin pseudohalides continue to be widely studied. Nitrosodicyanomethanides e.g.Ph,SnONC(CN) , are prepared from the corresponding silver salts.’& Stannyl carbodi-imides, e.g. Ph,SnNCNSnPh, give tin sulphides with thioureas and react with cyan-amide to give the cyanamide Ph,SnNHCN,94b Thiocyanogen cleaves an Sn-C bond of tetraorganotin derivatives Me,SnR (R = 2-butenyl 2-propynyl etc.) to form tin is~thiocyanates.’~‘ Metathetical exchange between tin alkoxides and aminosilanes gives sulphinylaminotin derivatives e.g. BU,S~NSO.’~ Exchange and hydrolysis of R,SnCl with sodium azide in water gives azidostannoxanes, e.g. (34).94e Me,SnCl and AgOCN give an isocyanate hydroxide Me,SnNCO, Me,SnOH ; Me,Sn groups are bridged by alternating nitrogen (from NCO) and oxygen (from OH) and there is extensive hydr~gen-bonding.’~f The stannyl-90 ( a ) R.C. Mehrotra and B. P. Bachlas J . Organometallic Chem. 1972 40 129; (6) A. G. Davies L. Smith and P. J. Smith ibid. 1972,39 279. 9 1 ( a ) M. Calligaris G. Nardin and L. Randaccio J.C.S. Dalton 1972 2003; (b) K. Kawakami M. Miya-Uchi and T. Tanaka J . Inorg. Nuclear Chem. 1971,33,3773. 92 ( a ) S. Kozima T. Itano N . Mihara K. Sisido and T. Isida J . Organometallic Chem., 1972 44 117; K. Sisido K. Nabika T. Isida and S. Kozima ibid. 1971 33 337; (b) R. Gassend M. Delmas J.-C. Maire Y. Richard and C. More ibid. 1972 42, C29. 93 (a) P. G. Harrison J.C.S. Perkin I 1972 130; (b) D. Hanssgen and R. Appel Chem. Ber. 1972 105 3271. 94 ( a ) H. Kohler U. Lange and B. Eichler J . Organometallic Chem. 1972 35 C17; (6) R. A. Cardona and E. J . Kupchik ibid. 1972,34 129; 1972,43 163; (c) M.L. Bullpitt and W. Kitching ibid. 1972 34 321 ; (4 D. A. Armitage and A. W. Sinden. ibid., 1972 44 C43; (e) H. Matsuda F. Mori A. Kashiwa S. Matsuda N. Kasai and K. Jitsumori ibid. 1972 34 341; (f) J. S. Thayer and D. P. Strommen ibid. 1966, 5 383; J. B. Hall and D. Britton Acra Crysr. 1972 B28 2133 228 D. W. A . Sharp M . G. H . Wallbridge and J . H . Holloway Bu 0 0 OH \ / \ / \ / Sn S Sn / \ / \ / \ HO 0 0 Bu (34) (35) phosphide Me,SnPHPh undergoes controlled oxidation to Me,SnOPHPh ; further oxidation appears to give a ph~sphonate.~~ Trialkyltin alkoxides can be prepared by thermal decomposition of a mixture of the oxide and the dialkyl carbonate or except for Me,SnOR and Et,SnOR, by distillation of the oxide and an alcohol.96 The compound [CpFe(CO),-SnPh(OSOPh)(OH)] contains two five-co-ordinate tin atoms linked by two hydroxyl bridge^.^'" The species [(EtSn) o(OH)28]2 + which is present in basic aqueous solutions of ethylstannyl derivatives depolymerizes to [(Etsn),(OH),,] +, [(EtSn),(OH),,] and [(EtSn),(OH),,]- on increasing the pH; in 1M-NaOH, EtSn(OH) and [EtSn(OH),]- are present.97b Insoluble polymeric peroxides are formed when R,Sn(OMe) are treated with hydrogen per~xide.~' The adduct formed bet ween triphenylphosphineacetylmethylene and SnCl has an 0 -+ Sn bond rather than a C-Sn bond as is found in the corresponding methylene~.~~ From Mossbauer spectroscopy it is concluded that Me,SnNO has planar Me3Sn groups with bridging nitrates Me,Sn(NO,)H,O has a planar Me3Sn group with co-ordinated unidentate nitrate and water.' Oob A similar geometry is found in the hydroxamate Ph,SnONPhCOPh the carbonyl oxygen being intramolecularly co-ordinated.l o l a Stannyl oximes e.g. Me,SnONHCOPh, are readily formed from hydroxylamines and the tin oxide or hydroxide ;' ' I b benzil oximes give adducts with tin tetrahalides."'" Insertion reactions of SO, into Sn-C bonds continue to receive wide study. In related studies it has been shown that oxidation of alkyldithiostannonic acids with hydrogen peroxide gives orthosulphites e.g. (35).'02 1 1 and 1 2 addition compounds of R,SnCl, (R = Me or Ph) with R,EO (E = C N P or S) all have 0 -+ Sn bonding. The 9 5 P. G. Harrison S. E. Ulrich and J. J. Zuckerman Inorg. Chem. 1972 11 25. 9 6 (a) A. G. Davies D.C. Kleinschmidt P. R. Palan and S. C. Vasishtha J. Chem. Soc. (0 1971 3972. 9 7 (a) R. Restno and R. F. Bryan J. Chem. Soc. ( A ) 1971,3364; ( 6 ) M. Devaud J. Chim. phys. 1972 69 460. 98 R. L. Dannley W. A. Ave and A. K. Shubber J. Organomerallic Chem. 1972 38, 281. 9') J. Buckle P. G. Harrison T. J . King and J. A. Richards J.C.S. Chem. Comm. 1972, 1104. l o o (a) R. C. Poller and J. N. R. Ruddick J. Organomerallic Chem. 1972 39 121; (b) R. E. Drew and F. W. B. Einstein Acta Cryst. 1972 B28 345. Io1 (a) T. J. King and P. G. Harrison J.C.S. Chem. Comm. 1972 815; (6) P. G. Harrison, J. Organomelallic Chem. 1972 38 C 5 ; (c) K. M. Ah J. Charalambous and M. J. Frazer J.C.S. Dalton 1972 207. l o * C. H. Stapfer and R. H. Herber J. Organomerallic Chem. 1972 35 11 1 The Typical Elements 229 bis complexes generally have cis-C1 and cis-donor arrangements; the 1 1 complexes generally have trigonal-bipyramidal geometry about tin with the donor and one C1 in the apical position^."^ (MeSn),S has the expected adamantane-like structure.O4 Dicyclopentadienyltin(I1) and SnX (X = C1 or Br) interact to give a new series of tin(r1) compounds CpSnX which probably contain halogen bridges.lo5 One of the products from the reaction between CpMo(CO),Cl and (Me,Sn),S is [Cp3M03S4]+ [Me,SnCl,]- having a trigonal-bipyramidal anion with a planar Me,Sn group.'06 Solvolysis of methyltin chlorides in anhydrous HF gives for example MeSnF and mixed chloride fluorides. lo' Sn[(OC2H,)2NC2H,0H]2 prepared from SnC1 and triethanolamine has octahedrally co-ordinated tin;'" tin(1v) ethylenediaminetetra-acetate mono-hydrate has seven-co-ordinate tin co-ordination being from two nitrogens four carboxylate oxygens and the water.Ethyleneurea is considered to co-ordinate to SnX (X = C1 Br or I) through the oxygen; ethylenethiourea co-ordinates through the imino-nitrogen. l o The phase Sno.,P is now recognized as SnP,; the structure contains layers of puckered P6 rings connected by Sn atoms and is related to one of the forms of arsenic;"' the phase GeP is iso-structural. The distorted co-ordination expected about tin(I1) is clearly shown in the structures of SnSO (pyramidal co-ordination by oxygen),' I 2a P-SnW04 (three short plus three long bonds),' 12' and the hydrates 2SnBr,,H,0"2' and 6SnBr2,-5H20' l Z d (trigonal prismatic with extra atoms in faces).Addition of dioxan to an alcoholic solution of SnCl gives crystals of (SnC1,0H,H20),,3dioxan. Each tin(rv) atom has octahedral co-ordination and tin atoms are linked by bridging hydroxy-groups to form dimers ; the dioxan molecules are unco-ordinated. ' l 3 Many tin(rv) complexes of oxygen-containing ligands have been described but only characterized structurally by spectroscopic means. Tin@) is extracted from SnC1,-HCI solutions generally as SnCl, 2H20 and H2SnC16 although solutions in tributyl phosphate (TBP) contain cis-SnC14,2TBP. SnCl in disulphuric acid gives H,[Sn(HSO,),].' Addition of base to the previously B. V. Liengme R. S. Randall and J . R. Sams Canad. J . Chem. 1972,50 3212. D . Kobelt E. F. Paulus and H.Scherer Acta Cryst. 1972 B28 2323. P. J. Vergamini H. Vahrenkamp and L. F. Dahl J . Amer. Chem. SOC. 1971,93,6327. H . Follner Monarsh. 1972 103 1438. l o ' K. D. Bos E. J. Bulten and J. G. Noltes J . Organometallic Chem. 1972 39 C52. l o ' L. E. Levchuk J. R. Sams and F. Aubke Inorg. Chem. 1972 11 43. ' O M l o ' F. P. van Remoortere J . J . Flynn and F. P. Boer Inorg. Chem. 1971 10 2313. ' l o P. P. Singh and 1. M. Pande J . Inorg. Nuclear Chem. 1972,34 591. ' I 1 J. Gullman and 0. Olofsson J . Solid State Chem. 1972 5 441. 'I2 (a) J. D . Donaldson and D . C. Puxley Acta Cryst 1972 B28 864; ( b ) W. Jeitschko and A. W. Sleight ibid. p. 3174; (c) J . Anderson Acta Chem. Scand. 1972 26 1730; (4 J. Anderson ibid. p. 2543. N. G. Bokii and Yu. T. Struchkov J .Struct. Chem. 1971 12 253. (a) M. J . Taylor J. R. Milligan and D. L. Parnell J . Inorg. Nuclear Chem. 1972 34, 2133; ( 6 ) R. C. Paul J . K. Puri V. P. Kapila and K. C. Malhotra ibid. p. 2141; ( c ) D . W. Thompson J . F. Lefelhocz and K. S. Wong Inorg. Chem. 1972 11 1139; (d) R. C. Paul V. Nagpal and S. L. Chadha Inorg. Chim. Acla 1972 6 335; ( e ) P. G. Harrison B. C. Lane and J. J. Zuckerman Inorg. Chem. 1972 11 1537 230 D. W. A . Sharp M. G. H. Wallbridge and J. H . Holloway described adducts Cl,Sn(acacH) gives the anionic species [SnCl,(acac)] -. 14c Alkoxytin(1v) trihalides give 1 1 adducts with ligands containing P-0 and N-0 bonds;114d the tetrahalides give 1 2 adducts with similar oxygen-contain-ing and also phosphine and arsine ligands and cis- and trans- isomers of these adducts have been identified.4e The phases present in the Na,S + SnS system are Na,SnS, Na,Sn,S,, Na,SnS and Na,Sn,S ."" The Sn2S76- ion in Ba,Sn,S7 contains linked tetrahedra. l 1 '' PbSnS3 has the Sn,S,-type structure with chains of SnS octa-hedra ; PbSnSeS is also known. l l 5c New chalcogenide halides including Sn,SI, Sn,SeI, and Sn,SBr, may be prepared by direct interaction of the components. SnC1,F2 is readily formed from SnCl and anhydrous HF; it reacts with fluorosulphuric acid to give SnF,(SO,F) .lo Sn,BrF5 contains an infinite tin(@ fluoride cationic network and free bromide ions; each tin atom has the typical tin(@ pyramidal co-ordination ;' Sn,Cl,' + dimer cations are present in ArSnCl(AlC1,) (Ar = C6H6 or p-xylene) and there is axially symmetrical interaction between the aromatic hydrocarbon and the tin."" Tin@) iodide has a new layer structure; two-thirds of the tin atoms are in SnC1,-like five-co-ordination and one-third are in PdC1,-like chains with octahedral co-ordination completed from other halogens.' lSc Pyramidal SnC1,- species are present in both forms of [Co(dpe),-ClISnC1 (dpe = Ph2PCH,CH,PPh2).' Mixed tin@) halides in particular the new SnBrC1 may be prepared from the component halides e.g.SnBr and SnCl , by the use of explosive shock compression."' SnC1 interacts with multiple carbon-carbon bonds as do SiF and carbenes; products of the type (36) are formed. Lead.-Pb and Pb can be trapped in matrices at 20K.122 Organolead thio-cyanates e.g. Me,PbNCS and Ph,Pb(NCS), have Pb-N bonds and are thus Many hexafluorostannates M"SnF have been described.'c =c-(36) R R ( a ) F. Vermont-Gaud-Daniel and J.-C. Jumas Compt. rend. 1972 275 C 741 ; (6) J.-C. Jumas M. Ribes and E. Philippot ibid. 1971 273 C 1356; (c) J.-C. Jumas, M. Ribes E. Philippot and M. Maurion ibid. 1972,275 C 269. F. Thevet N. H. Dung and C. Dagron Compr. rend. 1972,275 C 1279. R. Hoppe V. Wilhelm and N. Muller 2. anorg. Chem. 1972 292 1. 1 1 * ( a ) J. D. Donaldson and D. C. Puxley J.C.S. Chem. Comm. 1972 289; (b) M. S. Weininger P. F. Rodesiler A. G. Gash and E. L. Amma J . Amer. Chem. SOC. 1972, 94 2135; (c) R. A. Howie W. Moser and I. C. Trevena Acta Crysr. 1972 B28,2965. J. K. Stalick D. W. Meek B. Y. K. Ho and J. J. Zuckerman J.C.S. Chem. Comm., 1972,630.I2O S. S. Batsanov V. F. Lyakhova and E. M. Moroz Russ. J . Inorg. Chem. 1971,16,1233. l P. G. Harrison Inorg. Nuclear Chem. Letters 1972,8 5 5 5 . L. Brewer and C.-A. Chang J . Chem. Phys. 1972,56 1728 The Typical Elements 23 1 isothiocyanates. ' Triorganolead triazoles may be synthesized from tetra-organolead derivatives and l-chloro-1,2,3-triazoles.123b The reactions between N204 and tetra-alkyl-leads have been re-examined and shown to give organolead nitrates R,PbN03 and R,Pb(NO,),. 124 Polymeric Me,Pb(OR) derivatives result from the reaction between Me,Pb(C-CMe) and alcohols Me,PbX (X = OMe or NMe,) give trans-addition across the triple bond of CF,C-CCF . 25b Oxygen- and nitrogen-donor complexes of PhPbAc and Ph,PO complexes of diphenyl-lead halides have been described.' 26 Matrix-isolation studies on lead oxide vapours have identified the species PbO Pb,O (6 symmetry) and Pb404 (& symmetry) all similar to species observed with other Group IV element^.',^ A detailed study has been made on the thermal decomposition of lead dioxide. The system is very complex and depends upon the samples used but PbO Pb,O, Pbo1.55-1.40 and Pb12O19 (three forms) are formed.' 28 Cs,PbO contains five-co-ordinate lead(1v) ; the square-pyramidal units are joined together in :[PbO,,,O '3 chains. '29 Eight-co-ordinate lead is present in [Me,N] [Ph,PbAc,] ; the geometry is approximately hexagonal-bipyramidal with the phenyl groups in axial positions and each acetate bidentate.l3' The thermal decomposition of lead@) nitrate proceeds through the phases 2Pb0,Pb(N03) -+ 3PbO,Pb(NO,) -+ 4PbO,Pb(NO,) -+ PbO.' Thehydratedand basiclead(r1)oxidesformedfromNaOH and Pb(NO,), at 300 K have been very thoroughly investigated ;I3'' phases Pb(N03),,5Pb0,-$H,O and 3Pb(N0,),,7Pb0,5H20 have been identified.' '' Sulphur co-ordination about lead shows a wide variety of arrangements.Four-co-ordinate pyramidal monomers are found in Pb(S,CNEt,) and Pb[S,P(OEt),], whilst the isopropyl analogue Pb[S2P(OPri),] has very distorted six-co-ordina-tion approximating to a pentagonal bipyramid with a lone pair in an equatorial position. ' 3 2 b A distorted octahedral co-ordination by sulphur is also found in one form of Pb(thiourea) (ClO,),' 32c (the other form is eight-co-ordinate' 32d) ( a ) N. Bertazzi G . Alonzo A.Silvestri and G. Consiglio J. Organometallic Chem., 1972 37 281 ; ( 6 ) B. C. Pant and J. G. Noltes ibid. 1972 36 293. K. C. Williams and D. W. Imhoff J. Organometallic Chem. 1972 42 107. ( a ) R. J. Puddephatt and G. H. Thistlethwaite J.C.S. Dalton 1972 570; (b) R. J. Puddephatt and G. H. Thistlethwaite J. Organometallic Chem. 1972 40 143. l Z 6 H.-J. Haupt Z. Naturforsch. 1972 27b 724; H.-J. Haupt and F. Huber J. Organo-metallic Chem. 1971 33 175. "' J. S. Ogden and M. J. Ricks J. Chem. Phys. 1972 56 1658; c.f. D. W. A. Sharp, M. G. H. Wallbridge and J. H. Holloway Ann. Reports 1970,67 A 293 295. "* M. I. Gillibrand and B. Halliwell J. Inorg. Nuclear Chem. 1972 34 1143. P. Panek and R. Hoppe Z. anorg. Chem. 1972 293 13. ' 3 0 N. W. Allock J.C.S. Dalton 1972 1189.1 3 ' ( a ) E. V. Margulis M. M. Shokarev L. A. Sav'chenko L. I. Beisekeeva and F. I. Vershinina Russ. J. Inorg. Chem. 1972 17 21; ( 6 ) H. Brusset J. J. P. Martin C. Martin-Lefevre Y. Repelin E. Husson and B. Despagne Canad. J. Chem. 1972,50, 184; (c) J. J. P. Martin C. Martin-Lefevre and B. Despagne Bull. SOC. chim. France, 1972 2573; J. J. P. Martin C. Martin-Lefevre Y. Repelin and E. Husson ibid., p. 3341. 13' ( a ) H. Iwasaki and H. Hagihara Acta Crysr. 1972 B28 507; ( 6 ) Sr L. Lawlon and G. T. Kokotailo Inorg. Chem. 1972 11 363; ( c ) I. Goldberg and F. H. Herbstein, Acta Cryst. 1972 B28 400; (d) J. C. A. Boeyens and F. H. Herbstein Inorg. Chem., 1967,6 1408; ( e ) F. H. Herbstein and M. Kaftory Acta Crysr. 1972 B28 405 232 D. W. A . Sharp M. G.H. Wallbridge and J. H. Holloway and in Pb(thiourea) picrate,' 32e whilst tetragonal-prismatic co-ordination is present in $Pb(HC00),,4thiourea.' 3 3 Ammonium hexafluoroplumbate(Iv), (NH,),PbF, is formed from Pb(OAc) and hydrofluoric acid.'34 NaPbC1 is present in the vapour phase over heated NaCl-PbCl mixtures.' 35 2 GroupV Nitrogen.-Although in the gas phase atomic nitrogen reacts with organic compounds with carbonsarbon bond cleavage in condensed phases controlled insertion reactions appear possible and nitriles e.g. ClCH,CN from H,C= CC1 and amides e.g. CH,CONH from C,H50H are formed.'36b Further generalizations on hydrogen-bonding are now becoming apparent. In ammonium salts the co-ordination number can range from four to nine. When it is small, hydrogen-bonding is the most important aspect of the bonding from NH,'; when it is larger the ion is behaving as an alkali metal of size midway between the Rb+ and Cs+ ions.'37d Hydrogen-bonding appears to be responsible for the stability of the trans-rotamer of CF,CH,NH, which contains two potential hydrogen bonds.' 7 b Di-imine HNNH can be isolated as an unstable but pure material by thermal decomposition of alkali-metal toluene-p-sulphonylhydrazides M(Tos)NNH . 38 Pure anhydrous hydrazine is obtained by heating hydrazinium cyanurate in a vacuum.'39 N,(CF,) exists only in the gauche-form; in X2Y4 molecules an increased X-X bond length favours the trans-form as does increased electro-negativity of the substit~ents.'~~ Free hydrazoic acid may be obtained on an ion-exchange column ; it has been used to prepare hydrazinium azide N,H,N , i.e.N5H5 .141 H,NO- + H') of hydroxyl-amine has been determined as pK = 13.71 comparable with that ofmethan01.l~~ The molecular structure of (CF,),NOH shows a longer N-0 bond and a smaller ONC angle than in the radical (CF,),N0.'43a The mercurial [(CF,),NO],Hg reacts with CF,N CF to give {[(CF,),NOCF2](CF,)N},Hg which gives CF,N=C[ON(CF,),]OC[ON(CF,),I=NCF and CF,N=CFON(CF,) on The acid dissociation constant (for H2NOH 1 3 3 I . Goldberg and F. H. Goldstein Acta Cryst. 1972 B28 410. 1 3 4 R. L. Davidovich and T. A. Kaidalova Russ. J . Znorg. Chem. 1971 16 1354. 1 3 5 H. Bloom S. R. Richards and D . J. Williams Austral. J . Chem. 1972 25 2077. 1 3 b (a) J. J. Have1 and P. S. Skell J . Amer.Chem. SOC. 1972 94 1792; ( b ) C. T. Chen and N . N . Lichtin ibid. 1971,93 5922. 1 3 ' (a) A. A. Khan and W. H. Baur Acta Cryst. 1972 B28 683; (b) I . D. Warren and E. B. Wilson J . Chem. Phys. 1972,56,2137. 1 3 * N. Wiberg H. Bachhuber and G. Fischer Angew. Chem. Infernat. Edn. 1972,11,829. 1 3 9 E. Nachbaur and G. Leiseder Monarsh. 1971,102 1718. 140 J. R. Durig J. W. Thompson and J. D. Witt Znorg. Chem. 1972 11 2477. 1 4 1 G. Pannetier and F. Margineanu Bull. SOC. chim. France 1972 2617. 14* M. N . Hughes H. G. Nicklin and K. Shrimanker J . Chem. SOC. ( A ) 1971 3485. 143 ( a ) C . Glidewell C . J. Marsden A. G. Robiette and G. M. Sheldrick J.C.S. Dalton, 1972 1735; (b) R. E. Banks D. R. Choudhury R. N . Haszeldine and C. Oppenheim, J . Organomerallic Chem.1972 43 C20 The Typical Elements 233 heating.'43b The radical anion N,O- is formed in aprotic solvents on irradia-tion of N 2 0 with Gaseous HNO reacts immediately with NH to form NH,NO ; all of these species are present in polluted atmosphere^.'^^ Peroxonitrite can react to give both nitrite and nitrate as products; the metal-ion-catalysed self decomposition and reaction with peroxide both give nitrite as compared with isomerization to nitrate in alkaline solution.'46a The action of fluorine on NO2 gives the new fluoro-oxy-compound ONOF in low yield;'46b (CF,S),NH reacts with CF,SNCO or (CF,S),NC(O)NCO to give (CF,S)3N.'46' FS0,NCO reacts with alkali-metal fluorides in acetonitrile to give salts M [N( SO,F)C(O)F] . ' 466 NF4+BF4- has been prepared as have other salts of the NF4+ cation by irradiation of an NF,-BF,-F mixture.Irradiation at 77 K with excess fluorine gives a white solid which may be NF4+F-.14' BuN(F)NO, the first N-fluoro-nitramine may be synthesized by fluorination of aqueous alkali-metal salts of butylnitramine or by treating methyl-N-butyl-N-fluorocarbamate BuNFC02Me, with nitric A detailed phase study has been made on the N0,F-HF system ; from spectroscopic and conductivity measurements it is concluded that N0,F is completely dissociated to NO2+ and F- in this ~olvent.'~' The ClNCl bond angle in nitrogen trichloride is 107.1" consistent with the trends exhibited by PCl and AsC1 but much lower than that for the isoelectronic molecule N(SiH,),. It is concluded that there is little delocalization of the nitrogen lone-pairs on to the chlorine atoms.''' Phosphorus.-Traces of iodine catalyse the sublimation of red phosphorus. ' ' The structures of several phosphides have been described during the year [see p. 229 ref. 1111. Lip and Lip contain polymeric sheet anions involving P6 rings;'52a Sr,P, contains isolated PT3- units.'52b Diphosphine reacts with anhydrous hydrogen fluoride to give PH and polyphosphine (PH),; at high HF ratios H,PF is formed;'53 The P-P bond length in disphosphine is 0.026 A shorter than in Me,PPMe, a pattern similar to that in H,S2 as com-pared with Me,S2 but different from that of H6Si2 as compared with Me6Si,, where the bond lengths are almost Several new PH-containing com-144 S. P. Mishra and M. C. R. Symons J.C.S. Chem. Comm. 1972 510.1 4 s E. D. Morris jun. and H. Niki J. Phys. Chem. 1971,75 3193. 146 ( a ) M. N. Hughes and H. G. Nicklin J . Chem. SOC. ( A ) 1968 450; M. N. Hughes, H. G. Nicklin and W. A. C. Sackrule ibid. 1971 3722; (6) J. E. Sicre and H. J. Schu-macher 2. anorg. Chem. 1971,385 131 ; ( c ) A. Haas and R. Lorenz ibid. p. 33; (d) J. A. Rodriguez and R. E. Noftle Inorg. Chem. 1971 10 1874. 1 4 ' C. T. Goetschel V. A. Campanile R. M. Curtis K. R. Loos C. D . Wagner and J . N . Wilson Inorg. Chem. 1972 11 1696. 148 V. Grakauskas and K. Baum J. Org. Chem. 1972,37 334. 149 F. Seel and V. Hartmann J . Fluorine Chem. 197213 2 27 99. H. B. Burgi D. Stedman and L. S. Bartell J . Mof. Structure 1971 10 31. 5 1 H. Schafer and M. Trenkel Z . anorg. chem. 1971,391 1 1 . s 2 ( a ) H.-G.von Schneringand W. Wichelhaus Naturwiss. 1972,59,78; ( b ) W. Dahlmann and H.-G. von Schnering ibid. p. 420. F. Seel and K. Velleman Z . anorg. Chem. 1971,385 123. Holywell J. Struct. Chem. 1972 11 371. l S 4 B. Beagley A. R. Conrad J. M. Freeman J . J. Monaghan B. G. Norton and G. C 234 D. W. A . Sharp M . G. H . Wallbridge and J . H . Holloway pounds have been described. Hydrogen fluoride and water react with RPCl, to give phosphonous acid fluorides RP(H)(O)F' '" whilst pyramidal radicals HP02- HP03- and PO:- can be generated in aqueous solution by the action of Ti3 + and H 2 0 2 on hypophosphorous or phosphorous acids. '"' Detailed spectroscopic studies on HPF and H,PF confirm that hydrogen is present in the equatorial positions of trigonal bipyramids."'' H,PPF has a trans con-formation in the gas phase156a whereas Cl,PNMe is gauche with the PNC, portion of the molecular planar'56b (see p.232 ref. 140). Considerable interest continues to be taken in the geometry and mode of rearrangements of phosphorus particularly pentaco-ordinated phosphorus, compounds. Structural data on acyclic organophosphorus compounds published up to 1971 have been collected. Articles on pentaco-ordinated compounds include reference 157b. The structure of Ph,P=C=PPh has been determined and in crystallographically independent molecules the PCP angles are 144" and 1 30° of the same order of magnitude as in related molecules. ' Spectroscopic studies suggest that phosphabenzene C,H,P is planar. '"' The four-membered-ring compound (CF,PCF,) is formed from (CF,),PH and dimethylzinc ;l 59a phosphines and phosphites add to trifluoromethyl-substituted 2-aza-1,3-butadienes to give C-phosphorus derivatives e.g.R,P=C(Ph)CH= NCH(CF,) . l S g b Tris(carboxy)phosphines e.g. P(CO,R) are formed by the action of chloroformates on sodium phosphide. 160 Dimethylketen reacts with a variety of phosphines PXYZ to give compounds (37) which have trigonal-bipyramidal structures. 16'* P-OR' groups are readily converted into PR2 by use of R2X and NaA1H2(OCH,CH20Me)2.'6'b 1 5 5 ( a ) U. Ahrens and H. Falius Chem. Ber. 1972,105,3317; (6) A. L. J. Beckwith Austral. J. Chem. 1972,25 1887; ( c ) R. R. Holmes and C. J. Hora jun. Inorg. Chem. 1972,11, 2506. 156 ( a ) R. L. Kuczkowski H. W. Schiller and R. W. Rudolph Znorg.Chem. 1971 10, 2505; ( b ) J. R. Durig and J. M. Casper J. Phys. Chem. 1971,75 3837. 15' ( a ) L. S . Khaikin and L. V. Vilkov Russ. Chem. Rev. 1971,40 1014; (b) R. R. Holmes, Accounts Chem. Res. 1972,5 296; J. I. Musher J. Amer. Chem. Sac. 1972,94 5662; A. Rauk L. C. Allen and K. Mislow ibid. p. 3035; J. B. Florey and L. C. Cusachs, ibid. p. 3040; R. Hoffmann J. M. Howell and E. L. Muetterties ibid. p. 3047. ( a ) A. T. Vincent and P. J. Wheatley J.C.S. Dalton 1972 617; (b) R. L. Kuczkowski and A. J. Ashe tert. J. Mol. Spectroscopy 1972,42,457. 5 9 ( a ) D.-K. Kang and A. B. Burg J.C.S. Chem. Comm. 1972,763; (b) K. Burger J. Fehn, J. Albanbauer and J. Friedl Angew. Chem. Znternat. Edn. 1972 11 319. 160 A. W. Frank and G. L. Drake jun. J. Org. Chem. 1971,36 3461.1 6 1 ( a ) W. G . Bentrude W. D. Johnson and W. A. Khan J. Amer. Chem. SOC. 1972,94, 3058; (6) R. B. Wetzel and G. L. Kenyon ibid. p. 1774 The Typical Elements 23 5 Chloramines react with tertiary phosphines and arsines to give the correspond-ing amino-phosphonium and -arsonium chlorides e.g. [Ph,PNClR]Cl and [HN{ p,p'-(o-C,H,),}As(Me)NH,]Cl. 162 Cyclophosphamide hydrate (38) has a chair form ring with an equatorial amino-group and an axial phosphoryl oxygen ; this conformation about phosphorus is in contrast to that found for other systems without the amino sub~tituents.'~~ Wurtz coupling of F,PI and (CF,),PI or a redistribution reaction involving (CF,),PP(CF,) and P,F gives (CF,),PPF ; the PF group is basic to BH but the (CF,),P group does not appear to co-ordinate.164 Phenyl-lithium does not immediately completely cleave cyclo-polyphosphines but for example (EtP) gives Et(Li)P.PEt.PEt.P(Et)Ph ; the acylic derivatives are rapidly attacked by excess phenyl-lithium. ' 6 5 Cyclo-carbaphosphanes (PR'),(CRi) (n = 4 rn = 1; 11 = 3 m = 2) are formed from dihalides and potassium salts of cyclophosphides e.g. K,(PhP) with ClCH,.-CH,Cl gives (39).'66 In polar media biphosphines aggregate with formation of HlC-CH, I \ PhP\ P/PPh Ph (39) P-P donor-acceptor bonds. 67a Similar bonding is postulated in the adducts, e.g. [Et,PP(O)Cl,]Cl formed by phosphines and arsines and phosphoryl and thiophosphoryl halides. 67b Dimethylchlorophosphine reacts with NaOMe and NaSMe to give Me,PEMe ; Me,POMe rearranges slowly to Me,PO but Me,PSMe gives a stable phos-phonium salt which only gives Me,PS at 420 K.Me,POMe reacts with hydrogen chloride to give unstable [Me,P(H)OMe]Cl the thio-analogue may be present 1 6 * L. K. Krannich and H . H. Sisler Inorg. Chem. 1972 11 1226; S. E. Frazier and H. H. Sisler ibid. p. 1431 ; R. M. Kren and H. H. Sisler ibid. p. 2630. 1 6 3 J . C . Clardy J. A. Mosbo and J. G. Verkade J.C.S. Chem. Comm. 1972 1163. 164 H. W. Schiller and R. W. Rudolph Inorg. Chem. 1971 10 2500. 1 6 5 K. Issleib and F. Krech 2. anorg. Chem. 1971,385,47. I h 6 M. Baudler J. Vesper P. Junkes and H. Sandmann Angew. Chem. Internat. Edn., 1971 10 940; M. Baudler J. Vesper and H. Sandmann 2. Naturforsch. 1972 27b, 1007. 1 6 ' ( a ) H. C. E. McFarlane and W. McFarlane J.C.S. Chem.Comm. 1972 1189; ( b ) E. Lindner and H. Beer Chem. Ber. 1972 105 3261 236 D. W. A . Sharp M . G. H . Wallbridge and J. H. Holloway as an intermediate in the raction of Me,PSMe but decomposes to [Me,PH,]Cl and [Me,P(SMe),]Cl ; the latter compound decomposes.on heating to Me,P(S)-($Me). 68 Tetramethyl(methoxy)phosphorane Me,POMe and its homologues are readily formed from alcohols and trimethyl(methylene)phosphorane Me,P= CH ;169a Ph,POPh decomposes thermally to Ph,P and phenol whereas Ph,SbOR (R = alkyl) gives Ph,Sb ketones benzene and simple ethers in a very distinct reaction. '"' Phosphines Ar,P react with thionyl chloride initially by oxygen abstraction to Ar,PO and then through reaction with SC1 to give Ar,PC12 and Ar,PS; the corresponding arsines and stibines react to give for example Ar,AsCl by halogen transfer.' 7 0 Ph,P(O)OOP(O)Ph decomposes in chloroform to the unsymmetrical anhydride Ph,P(O)OP(O)(OPh)Ph. 17' 1,2-Oxaphosphetans e.g. (40) are formed by the reaction of electrophilic carbonyl OMe derivatives e.g. CF,COCF, with POR derivatives ;172a the ring system is bonded axial-equatorial in the trigonal bipyramid. EtPPh reacts with hexafluoroacetone to give (41a) which isomerizes to (41b) at 620 K ; both of the oxygen atoms in the latter compound are in apical positions with the ring 1 6 ' F. See1 and K.-D. Velleman Chem. Ber. 1972 105 406. 169 ( a ) H. Schmidbaur and H. Stiihler Angew. Chem. Infernat. Edn. 1972 11 145; (b) G. A. Razuvaev and N. A. Osanova J . Organometallic Chem. 1972,38 77. " O E. H.Kustan B. C. Smith M. E. Sobeir A. N. Swami and M. Woods J.C.S. Dalton, 1972 1327. l 7 I R. L. Dannley R. L. Waller R. V. Hoffman and R. F. Hudson J . Org. Chem. 1972, 37 418. 1 7 * (a) F. Ramirez G . V. Loewengart E. A. Tsolis and K. Tasaka J . Amer. Chem. Soc., 1972 94 3531; ( 6 ) Mazhar-ul-Haque C. N. Caughlan F. Ramirez J. F. Pilot and C. P. Smith ibid. 1971 93 5229; (c) D. D. Swank C. N. Caughlan F. Ramirez and J. F. Pilot ibid. p. 5236 The Typical Elements 237 axial-equatorial.' 7 2 b The oxygen atoms in (42) formed from Ph,POEt and tram-PhC(O)CH=CHC(O)Ph followed by treatment with p-bromobenzalde-hyde are also in apical positions.' 72c The phosphorinan ring in (43) has a flattened Ph 0 7 Ph P I4 chair conformation with the chlorine in an axial position.73 Four-co-ordinate phosphorus compounds (except OPF,) are protonated in sulphuric acid and oleum ; sulphonation occurs after protonation ' 74a fluorophosphoric acids are protonated in HS0,F and HS03F-SbF5 solutions. Fluorosulphuric acid even-tually fluorinates and protonated FH,PO is formed :l 74b [ClMe,P](CO),Mo is hydrolysed in the presence of base to Me,P(OH)Mo(CO) in which the hitherto unknown dimethylphosphorous acid is stabilized by co-ordination ; the P-Cl bond in the original complex is active and an extensive chemistry can be carried out whilst the phosphorus remains co-ordinated. 75 Organophosphorus derivatives containing P=O P=S etc. bonds have an extensive co-ordination chemistry which has been reviewed. 7 6 a Many examples of complexes containing these groups have been described including complexes of Ph,P(O)NMe PhP(O)(NMe,) ,l 76c Me,NP(O)NMeP(O)(NMe,) , OP(NMe,),,'76d R',P(0)OP(O)R2, RP(0)(NMe,)OP(O)(R)NMe,,'76' 1 7 3 L.Silver and R. Rudman Acta Cryst. 1972 B28 574. 1 7 4 (a) P. Haake and P. S. Ossip J. Amer. Chem. Soc. 1971 93 6918; G. A. Olah and C. W. McFarland Inorg. Chem. 1972,11 845. C. S. Kraihanzel and C. M. Bartish J. Amer. Chem. SOC. 1972,94,3572. 1 7 6 ( a ) N. M. Karayannis C. M. Mikulski and L. L. Pytlewski Inorg. Chim. Acta Rev., 1971 5 69; ( b ) M. W. G . de Bolster and W. L. Groeneveld Z. Naturforsch. 1972, 27b 759; ( c ) M. W. G. de Bolster and W. L. Groeneveld Rec. Trav. chim. 1971,90, 1153; (d) J.-M. Carpentier R. Schlupp and R. Weiss Acta Cryst. 1972 B28 1278; M. W. G. de Bolster and W.L. Groeneveld Rec. Trau. chim. 1972 91 171 185; ( e ) M. D. Joesten and Y. T. Chen Inorg. Chem. 1972,11,429; J . Inorg. Nuclear Chem., 1972 34 237; (f) J. Crea and S . F. Lincoln ibid. p. 1 1 31 ; (g) A. N. Pudovik A. A. Muratova M. D. Medvedeva and 8. G. Yarkova J. Gen. Chem. (U.S.S.R.) 1971, 41,771 ; A. N. Pudovik A. A. Muratova 8. G. Yarkova and MD. Medvedeva ibid., p. 1486; C. M. Mikulski N. M. Karayannis and L. L. Pytlewski J. Znorg. Nuclear Chem. 1972 34 1215; (h) 8. G. Yarkova I. Y. Kuramshin A. A. Muratova,* and A. N. Pudovik J. Gen. Chem. (U.S.S.R.) 1971 41 1008; (i) A. A. Muratova E. G. Yarkova I. Y. Kuramshin and A. N. Pudovik ibid. p. 1676; ( j ) A. A. Muratova, I. Y. Kuramshin 8. G. Yarkova and A. N. Pudovik ibid. p. 1984; (k) D. A. Wheat-land C.H. Clapp and R. W. Waldron Inorg. Chem. 1972 11 2340; (1) A. Miiller, V. V. K. Rao and P. Christophliemk J. Znorg. Nuclear Chem. 1972 34 245; S. V. Larionov and L. A. Il'ina J. Gen. Chem. (U.S.S.R.) 1971 41 767 238 D. W. A . Sharp M. G. H . Wallbridge and J. H. Holloway (Me0)3P0176f (in all the above complexes co-ordination is through the phos-phoryl oxygen) R' POR' and (EtO),P(O)Cl (adducts are formed with halides followed by isomerization of the ligand to R',R2P0 co-ordinated to the metal; in some cases there is elimination of alkyl halides followed by formation of compounds containing POM links),' 76g (RO),P(O)OH,' 76h (RO),PO(SH) (complexing through the phosphoryl oxygen),'76i (R0)2PS2-,'76i R' ,P(S)-XP(S)R2 ,' 7 6 k R,PSeS- ' 761 (in all of the above co-ordination is from sulphur), and (RO),POSe-.' 76m Hydrolysis of (MeO)P(O)(SMe)NH in alkaline solution takes place by P-0 bond cleavage whereas in acid solution the predominant cleavage is of P-S bonds.'77 PhP(O)Cl reacts with HIS in the presence of base to give [PhP(S)O], with oxygen in the ring.'78 The phosphinic acid (CF,),P(S)OH is formed by the action of sulphuric acid on salts of the acid ; it is a moderately strong acid which may be dehydrated to [(CF,),P(S)],O which undergoes nucleophilic attack to (CF,),P(S)X (X = NMe, F C1 or Br).17' A compound containing the (0)PSCN grouping (neopentyl-O),P(O)SCN is formed by the sequence R,P(O)-SCl -R2P(0)SCN.'80 CF,SSCF reacts with(CF3P),and(CF,),PP(CF,), to give (CF,S),PCF and CF,SP(CF,) respectively ; I 8 '' small-ring-containing phosphines and phosphites react with 3,4-bis(trifluoromethyl)-1,2-dithieten to give sulphur-containing phosphoranes e.g.(44). ' '' MePFCl and MePFBr may be prepared by cleavage of aminofluorophos-phines with hydrogen halide.'82 Addition of hydrogen fluoride to ylides e.g. Me,P=CH gives tetra-alkylphosphonium fluorides although molecular phosphoranes appear to exist for some of the compounds ;18,' sulphur chloride pentafluoride and CF300CF3 are mild fluorinating agents for the formation of L 7 7 17' J. J. Daly L. Maier and F. Sanz Helv. Chim. Acta 1972,55 1991. 1 7 9 A. A. Pinkerton and R. G. Cavell J . Amer. Chem. SOC. 1972 94 1870. I a o A. topusinski and J. Michalski Angew. Chem. Internat. Edn. 1972 11 838. l S L (a) I. B. Mishra and A.B. Burg Inorg. Chem. 1972 1 1 664; (b) N. J. De'ath and M. A. H. Fahmy A. Khasawinah and T. R. Fukoto J. Org. Chem. 1972,37 617. D . B. Denney J.C.S. Chem. Comm. 1972,395. H. W. Schiller and R. W. Rudolph Inorg. Chem. 1972,11 187. ( a ) H. Schmidbaur K.-H. Mitschke and J. Weidlein Angew. Chem. Internat. Edn., 1972,11 144; (b) C. J. W. Fraser M. E. McCartney D . W. A. Sharp and J. M. Win-field J . Inorg. Nuclear Chem. 1972 34 1455; (c) N. J. De'ath D . Z . Denney and D. B. Denney J.C.S. Chem. Comm. 1972,272 The Typical Elements 239 fluorophosphoranes ;183b*c it is suggested that (45) may have the ring diequatorial in one spectroscopically observable form. 83c Cyclopentadienylphosphorus difluoride C,H,PF prepared from KC,H and PBrF, shows fluxional behaviour.Silylphosphinimines and sulphur(v1) imides react with fluorophos-phoranes to give aminophosphonium fluorophosphates e.g. [R,P(N=PR,) - ,] + [R,PF,-J- ( n = 1 or 2). The hitherto unknown [Me,PF,]- is one product of these r e a ~ t i 0 n s . l ~ ~ (CF,),NCl gives both direct addition and addition of FCI (and elimination of CF,N=CF,) with trifluoromethylphosphorus halides e.g. (CF,),PCl gives (CF,),NP(CF,),Cl and (CF,),PCl,F. Alkoxyfluorophos-phoranes are stable when the alkyl group is electronegative e.g. CH,CCl, or is the neopentyl group. Bis(fluorophosphinothioy1)sulphides [RFP(S)],S are formed from PhPF and cyclodiphospha(v)thianes R(S)P(p,p'-S,)P(S)R. 8 8 Phospham (PN,H), gives salts with alkali-metal amides. lg9' Very many derivatives containing P-N bonds continue to be described ; in addition to these mentioned in the present section some will be found on p.244 under the head-ing of substituted phosphorus halides. Heating (MeNPF,) gives (MeNPF,) , for which a cubane-type skeleton is postulated [(MeN),P3F6] [PF,] and (MeN),-P,F7 ; for these two latter compounds cubane-type structures with one missing corner are postulated. 89b Many phosphinimine derivatives are now known. Me,P=NSiMe reacts with phosphorus chlorides to give substituted derivatives, e.g. (Me3P=N),P,l9'" and substituted disilanyl derivatives are formed from Me,P=NLi and for example Me,Si,Cl. l g o b Iminodichlorides e.g. PhN= P(NR,)Cl, react with symmetrical disubstituted ureas to give diphosphates e.g. [PhNHP(O) (NR,)] ,O. 90c Bisphosphimino derivatives e.g.[ClP(R I ) (R2)= NP(R3)(R4)Cl]Cl are formed from chlorophosphoranes and phosphinic thio-amides R,PSNH,. 90d Acetonitrile and phosphorus pentachloride react to 184 1 8 5 1 8 6 1 8 7 1 8 8 189 I 9 0 J. E. Bentham E. A. V. Ebsworth H. Moretto and D. W. H. Rankin Angew. Chem. Internat. Edn. 1972 1 1 640. W. Stadelmann 0. Stelzer and R. Schmutzler Z . anorg. Chem. 1971 385 142; R. Appel I . Ruppert and F. Knoll Chem. Ber. 1972 105 1492. H. G. Ang J . Fluorine Chem. 197213 2 181. D. V. Robert G. N. Flatau C. Demay and J . G. Riess J.C.S. Chem. Cumm. 1972, 1127. R. K. Harris J . R. Woplin M. Murray and R. Schmutzler J.C.S. Dalton 1972, 1590. ( a ) J. Goubeau and R. Pantzer 2. anorg. Chem. 1972 390 25; (b) K. Utvary and W. Czysch Monatsh. 1972 103 1048.( a ) W. Wolfsberger H. H. Pickel and H. Schmidbaur Z . Naturforsch. 1971 26b, 979; (6) H. Schmidbaur and W. Vornberger Chem. Ber. 1972 105 3187; (c) M. Bermann and K. Utvary Synrh. Znorg. Metal-org. Chem. 1971,1 171 ; (6) A. Schmid-peter N. Schindler and H. Eiletz ibid. 1972 2 187 240 D. W. A . Sharp M. G. H . Wallbridge and J. H . Holloway give [HCCl =C(NPCl ,) (PCl,)] [PCI,] whilst chloroacetonitrile gives HCCl= C(NPC1,)Cl. 1 9 ' Ph,PCH,PPh reacts with ammonia and carbon tetrachloride under pressure to give [Ph,P(NH,)N=P(Me)Ph,]Cl. Other biphosphines e.g. Ph,P(CH,),PPh give cyclic phosphonium salts (46) and the method provides (46) a good ,route to heterocyclic derivatives e.g. H,NX=NH and Ph,PCH,PPh, gives a XNPCPN heterocycle. 192 BCI and PCl react with ammonium chloride to give the phosphonitrilic precursor [Cl(Cl,P=N),PCl,] [BCl,].' 9 3 Mono-phosphazenes react with silazanes e.g. (Me,Si),NH to give compounds of the type SPF,N=PCl,NHSiMe which react further with PCI to give diphos-phazenes e.g. SPCl,N=PF,N=PCl SPCl,N=PCl,N=PCl,NMeSiMe, decomposes to the cyclic phosphazene (47). 194b Strong carboxylic acids hydrolyse CI P N* P a z II I sH \c1 (47) SPX,N=PX to SPX,NPH(O)X whilst weak acids e.g. acetic acid give SPX,NHC(O)CH derivatives. 194c Phosphinimines YN=PX (Y = MeSO,-, C1S02- or P,N,F,-) react with alcohols to give YN=PX,OR but these rearrange to YNRP(O)X with ether. 194d Ph,P(NH)N=P(NH,)Ph reacts with P(NMe,) with phosphonitrilic ring formation to give (48). ' 95 N Ph,P' +PPh, II I N /,N P / \ (48) Me,N H E.Fluck and W. Steck Z . anorg. Chem. 1972,387 349. 1 9 2 R. Appel R. Kleinstuck and K.-D. Ziehn Chem. Ber. 1972 105 2476. 193 K. Niedenzu I. A. Boenig and E. B. Bradley Z . anorg. Chem. 1972,393 88. * 9 4 ( a ) H. W. Roesky L. F. Grimm and E. Niecke Z . anorg. Chem. 1971 385 102; H. W. Roesky and W. Kloker Z . Naturforsch. 1972 27b 486; (6) H. W. Roesky, Chem. Ber. 1972 105 1439; ( c ) H. W. Roesky B. H. Kuhtz and L. F. Grimm Z . anorg. Chem. 1972,389 167; (d) H. W. Roesky and W. G. Bowing ibid. 1971 386, 191. 1 9 5 M. Bermann and J . R. van Wazer Inorg. Chem. 1972,11,209 The Typical Elements 24 1 Phosphazene particularly cyclophosphazene chemistry has been reviewed.'96 Phosphazenes can be reduced electrolytically to radical anions in non-aqueous media.19' Many structural studies on phosphazenes continue to be described. Amongst those which reveal new principles are the detection of two conformers at different temperatures for linear high-molecular-weight (NPF2) ; the low-temperature polymer has a cis,trans-planar chain conformation. ' 98a 2,2,4-C1 3-4,6,6-(NMe2),P,N has a distorted boat conformation with the 5-45 6-1 PN bonds longer than the others in the ring.'98b The difference in detailed geometry of two of the isomers of 2,4,6,8-Cl4-2,4,6,8-Ph4P4N4 suggests that steric factors are the most important influence on ring shape.'98' N,P,Brlo has a puckered ring (N,P,Cl is almost planar) with one re-entrant angle at a nitrogen atom. 198d A great deal of interest has been shown in the preparation of isomeric species, and many of the reactions involve formation of aminophosphazenes followed by replacement of the amino-group.P,N,F reacts with dimethylamine to give cis- and trans-1,3-P,N,F4(NMe,)21990 whilst P,N,Cl reacts with 8 moles of Me,NH to give trans-l,3-P,N,Cl,(NMe2)4 and some P,N,Cl(NMe,) . 199b P,N,Cl reacts with Me,NH to give various non-geminally substituted amino-phosphazenes. 199c The dimethylaminochlorides are fluorinated with SbF, preferentially at an amine-substituted phosphorus but total exchange of chlorine by fluorine can occur.199d Antimony trifluoride can substitute F for NMe in a non-geminal manner;'99e NMe can be substituted by C1 or Br (giving non-geminal isomers) by the action of hydrogen halide. 199s The reactions of P3N,F6 with amines diamines and hydrazines have been described ;'OO P,N,F,NH, (and SPF,NH2) react with boron chlorides to give derivatives such as (P,N3F,-NH),B ;"' isothiocyanatophosphazenes are prepared by the action of a thio-cyanate on the chlorophosphazenes in acetone.'02 NaON(CF,) gives phos-phazenes substituted by ON(CF 3)' groups.O3 A N4P ring compound (49) is formed from a succession of condensation reac-tion~.''~ The ring compound N~PCl,~NMe~BCl~NMe~PCl can be fluorinated 1 9 6 197 1 9 8 1 9 9 2 0 0 201 2 0 2 203 2 0 4 H. R. Allcock Chem. Rev. 1972,72 315. H. R. Allcock and W. J. Birdsall Inorg. Chem. 1971 10,2495. ( a ) H. R. Allcock R. L. Kugel and E. G. Stroh Inorg. Chem. 1972 11 1120; ( 6 ) F. R. Ahmed and D . R. Pollard Acta Cryst.1972 B28 513; (c) G. J . Bullen and P. A. Tucker J.C.S. Dalton 1972 1651 ; ( d ) J . G . Hartsuiker and A. J. Wagner ibid., p. 1069. ( a ) E. Niecke H. Thamm and D. Bohler Inorg. Nuclear Chem. Letfers 1972 8 261 ; (b) B. Green and D. B. Sowerby J . Inorg. Nuclear Chem. 1971 33 3687; ( c ) D . Millington and D . B. Sowerby J.C.S. Dalton 1972,2035; (4 B. Green D. B. Sowerby, and P. Clare J . Chem. SOC. ( A ) 1971 3487; ( e ) P. Clare D . Millington and D. B. Sowerby J.C.S. Chem. Comm. 1972,324; (f) P. Clare D . B. Sowerby and B. Green, J.C.S. Dalton 1972 2374. E. Niecke H. Thamm and G. Flaskerud Chem. Ber. 1971 104 3729; T. Chivers and R. Hedgeland Canad. J . Chem. 1972,50,1017. H. W. Roesky Chem. Ber. 1972,105 1726. R . L. Dieck and T. Moeller Inorg.Nuclear Chem. Letters 1972 8 763; T. Moeller and R. L. Dieck Synth. Inorg. Metal-org. Chem. 1972 2 19. P. 0. Gitel' L. F. Osipova and L. I . Kostikin J . Gen. Chem. (U.S.S.R.) 1971 41, 1416. A. Schmidpeter and K. Stoll Phosphorus 1971 1 103 242 D. W. A . Sharp M. G. H . Wallbridge and J. H. Holloway II \ N - N H (49) R2P p 2 with SbF or AsF without breaking the ring.205 Several examples of sulphur-containing rings have been described e.g. I(T-PCl,.N-SCl-N.PCl from S(N= S=O) and PC1 ,206a and also the corresponding sulphur(vI)=O compounds from O2 S(NH ,) and [Cl,P =NPC1 3] [PCl,] 06b or 0 S(N=PCI 3)2 and (Me Si) -NR,206c and sulphur(1v)-Me compounds.206d Isomers e.g. (50a b) are possible Me Ph P /fv\ PPh2 1 I 1 P ~ I ~ P / ~ \ P P ~ , II I1 (a) (50) in these systems,206e and related systems e.g.(NPCl,),NSOCl can be prepared by thermal decomposition of phosphinimine derivatives of sulphuryl chloride.206f Hydrogen sulphide reacts with phosphazene chlorides to give thiophosphamic acids [NP(SH),] ;,07 spirophosphoranes e.g ( 5 l) are formed from carboxylic R C / $ O N O N \c4 R (51) acid hydrazides and P(NMe,) .208 P(p,p',p''-[NMe],)P has planar PNNP links, suggestive of little n-bonding in the system.209 It seems probable that detailed 2 0 5 H. Binder Phosphorus 1972 1 287. 'Ob ( a ) H. W. Roesky Angew. Chem. Internat. Edn. 1972 11 642; (b) U. Klingebiel and 0. Glemser Z . Naturforsch. 1972,27b 467; ( c ) U. Klingebiel and 0. Glemser Chem. Ber. 1971 104 3804; 1972 105 1510; (d) R. Appel and K.-W.Eichenhofer ibid., p. 3859; ( e ) M. Bermann and J. R. van Wazer Inorg. Chem. 1972,11,2515; (f') H. H. Baalmann H. P. Velvis and J. C. van de Grampel Rec. Trau. chim. 1972 91 935. '07 B. Yanik and V. Zheshutko J . Gen. Chem. ( U . S . S . R . ) 1971 41 2668. ' 0 8 A. Schmidpeter and J. Luber Angew. Chew. Internat. Edn. 1972 11 306. * 0 9 W. vanDoorne G. W. Hunt R. W. Perry and A. W. Cordes Inorg. Chem. 1971, 10 2591 The Typical Elements 243 packing considerations greatly affect the geometry of many of these cyclic mole-cules. The monoclinic form of [O,P(NMe,),] has all exocyclic oxygens on one side of a chair-form ring whilst the orthorhombic form has two oxygens on one side of the ring which is planar except for one phosphorus atom.210 The action of sulphur on P4(NMe) gives adducts P4(NMe),S (n = 1-3) [P4(NMe)6S4 is also known] which appear to retain the P,(NMe) skeleton.2' ' Dimethylamino-chlorophosphines react with antimony pentachloride to give aminochlorophos-phonium salts e.g.[Me2NPCl,] [SbCl,]. l 2 Oxidationofphosphateanions in solution gives the radicals'P0,2-,'P020H-, 'HP02- and 'PhP02-.213 The use of 32P labelling shows that Up to fifteen different oxy-anions of phosphorus can be separated on an ion-exchange resin.214 Orthophosphoric acid in NNN'N'-tetramethylurea condensed with excess of a carbodi-imide gives a mixture of cyclic ultraphosphates. Hydrolysis yields cyclic metaphosphates (MPO,) to (MPO,),, and samples of the new compounds (NaPO,) (x = 5,7 or 9) were isolated.21 Neutral hypodiphosphorous esters e.g.C,H4O2P-PO2C6H4 are formed from the phosphorochloridite and sodium.21 In CuLi(PO,) infinite twisted (PO,) chains are pre~ent,~' 7a whilst BaNaP,O, contains P30 rings in a chair configuration217b and a P@15 ring anion is present in Na4NH4P5015,4H20.217c The anion in Na,P,O is in an eclipsed configuration with a POP angle of 127" ;,' 7d spectroscopic studies suggest that in sodium hypophosphates the H2P2062- anion is in an eclipsed configuration whilst it is in a staggered configuration in potassium Salk2 ' 7e The ester confor-mation in AgPO,(OEt) is syn-clina1,anti-clinal whereas in the barium salt the conformation has been found to be syn-clina1,syn-clinal. Various new peroxyphosphoric acids have been described. OP(OH)(OOH), is formed from P4010 P203Cl4 or OPC12(OH) and H202 whilst P203F4 reacts with H 2 0 2 to give OPF,(OOH).OPC1,F reacts with H 2 0 2 to give OPF(OH)(OOH).218 Sulphatophosphates e.g. [P04S0,]3- are formed from chlorosulphuric acid and phosphates in nitromethane. Triethylammonium 2 1 0 V. I . Andrianov N . G. Bokii V. D. Cherepenskii-Malov B. L. Tarnopol'skii and Yu. T. Struchkov Zhur. strukt. Khim. 1969 10 866; V. D. Cherepenskii-Malov, A. I . Gusev I. A. Nuretdinov and Yu. T. Struchkov ibid. 1971 12 126. 2 1 1 J. G. Riess and A. Wolff J.C.S. Chem. Comm. 1972 1050; c.f. R. R. Holmes and J. A. Forstner Znorg. Chem. 1963 2 377. 2 1 2 K. Press1 and A. Schmidt Chem. Ber. 1972 105 3518. 2 1 3 B. C. Gilbert J. P. Larkin R. 0. C. Norman and P. M. Storey J.C.S. Perkin ZZ, 1972 1508. 2 ' 4 M.Tominaga T. Nakamura and S. Ohashi J . Inorg. Nuclear Chem. 1972 34 1409. 'I5 T. Glonek J . R. van Wazer M. Mudgett and T. C. Myers Znorg. Chem. 1972 11, 567. ' 1 6 E. E. Nifant'ev A. I. Zavalishina and I . V. Komlev J . Gen. Chem. ( U . S . S . R . ) 1971, 41 1457. '17 (a) M. Laugt I. Tordjman J. C. Guitel and M. Roudaut Acta Cryst. 1972 B28, 2352; ( b ) C. Martin and A. Mitschler ibid. p. 2348; ( c ) K. H. Jost ibid. p. 732; (6) K. J . Leung and C. Calvo Canad. J . Chem. 1972 50 2519; ( e ) P. Klima J. Stejskal, and B. Hajek Specrrochim. Acta 1972 28A 1909; (f) J. P. Hazel and R. L. Collin, Acta Cryst. 1972 B28 2951 ; c.f. Y . Kyogoku and Y. Iitaka ibid. 1966 21 49. ' I 8 E. Fluck and W. Steck Z . anorg. Chem. 1972,388 53. 2 1 9 J.-C. Fischer G. Palavit M.Wartel and J. Heubel Compt. rend. 1972 274 C 867 244 D. W. A . Sharp M. G. H . Wallbridge and J. H. Holloway tris-(0-phenylenedioxy)phosphate(v) formed from catechol and tris-(0-phenyl-enedioxy)cyclotriphosphazene contains an octahedrally co-ordinated phosphorus atom. O Lead thiolates are good reagents for preparing thiophosphates and thio-phosphites;221 the conformation of the ester groups in K,S,P(OCH,C,H,) is syn-clinal anti-periplanar. 2 2 Various trifluoromethyl phosphates thiophos-phates and thiophosphites (CF3),PS2- (CF3),PSO- CF3P02- CF3PS202-, CF3PS022- CF3P03,- CF,PS,OH- CF,PSO,H- and CF3P(H)02- are formed by hydrolysis of trifluoromethylphosphorus-sulphur or -oxygen deriva-t i v e ~ . ~ ~ The existence of tetrahedral fluoroxyphosphate anions has been confirmed in the salts CaP03F,2H,0 (NH4),P0,F,H20 and (NH4),P0,F,-H,O.24 The structures of several halogenophosphorus pseudohalides have been described. In PF,CN the cyanide is tilted away from the f l u o r i n e ~ . ~ ~ ~ ' F,PNCO and F,PNCS have bent NCX units (see p. 215 ref. 8b) with the pseudohalide group trans to the bisector of the FPF angle,225b an arrangement similar to that in F,PN C NPF (prepared from F2PBr and Ag2CN,).225C The chlorine atoms in phosphorus chloride fluorides are readily exchanged for azide by use of sodium azide in various solvents.226 The nitrogen atom in PF,NH appears to be planar PF4NH2 may be prepared by the vapour-phase reaction between PF4C1 and ammonia.227b >NH groups readily undergo substitution into phos-phorus halides or the substitution may be effected indirectly by use of silylamines ; amongst compounds containing P-N bonds are hydrazine,228"* NSCC13,228C and S3N3228d derivatives.[Cl,P(O)],NMe undergoes multiple substitution by dimethylamino-groups ; the bis-compound is the non-geminal isomer. [Cl,P(S)],NR and Cl,PS-NR.PCl are formed from (Cl,P),NR and sulphur; on heating they eliminate PCl and give cyclodiphosphazenes ; [RNP(S)Cl] 0 Cl,P(S).NR-P(O)CI and [Cl,P(S)],NR can be prepared by condensation reac-t i o n ~ . ~ ~ ~ ~ Substitution of Me,N into Cl,P(O)NMePCl occurs first at the phosphorus(II1) atom but there is subsequent interchange to the phosphorus(v), 2 2 0 H. R. Allcock and E. C. Bissell J.C.S. Chem. Comm. 1972 676. 2 2 1 R. A. Shaw and M. Woods Phosphorus 1971,1,41 191.2 2 2 J. P. Hazel and R. L. Collin Acta Cryst. 1972 B28,2279. 223 A. A. Pinkerton and R. G . Cavell Inorg. Chem. 1971 10 2720. 2 2 4 A. Perloff Acta Cryst. 1972 B28,2183; A. F. Berndt and J. M. Sylvester ibid. p. 2191. 2 2 5 ( a ) P. L. Lee K. Cohn and R. H. Schwendeman Inorg. Chem. 1972 11 1917; (b) D. W. H. Rankin and S . J. Cyvin J.C.S. Dalton 1972 1277; ( c ) D. W. H. Rankin, ibid. p. 869. 2 2 6 S. R. O'Neill and J. M. Shreeve Inorg. Chem. 1972 11 1629; E. L. Lines and L. F. Centofanti ibid. p. 2269. 2 2 7 ( a ) A. H. Brittain J. E. Smith P. L. Lee K. Cohn and R. H. Schwendeman J. Amer. Chem. Sac. 1971 93 6772; (b) A. H. Cowley and J. R. Schweiger J.C.S. Chem. Comm. 1972 560. 2 2 8 ( a ) H. W. Roesky and 0. Petersen 2. Naturforsch. 1971,26b 1232; (b) M.D. Havlicek and J. W. Gilje Inorg. Chem. 1972 11 1624; H. W. Roesky W. Schaper and S. Tutkunkardes 2. Naturforsch. 1972. 27b 620; (c) H. W. Roesky and L. F. Grimm, Angew. Chem. Internat. Edn. 1972 11 642. 229 ( a ) I . Irvine and R. Keat J.C.S. Dalton 1972 17; (b) R. Keat ibid. p. 2189; ( c ) R. Keat Phosphorus 1972 1 253 The Typical Elements 245 and substitution of two NMe groups can give two isomers Cl(Me,N)P(O)-NMePClNMe and (Me,N),P(O)NMePCl .22 9c Fluoroisocyanatophos-phorus(v) derivatives e.g. (OCN),P(S)F are best prepared by fluorinating for example SP(NCO) with antimony trifluoride.,,' Fluoroaminophosphines form P + B bonds with borane fragments and N -+ B bonds with boron tri-f l ~ o r i d e . " ~ ~ ~ ~ ~ The compound (52) reacts with excess of BF to give [ MehCH,CH,( Me)NP] + [B2F7] - .Me (52) The thermally unstable complexes PX,,NMe (X = C1 or Br) appear to have trigonal-bipyramidal structures with an equatorial lone pair and axial nitrogen atoms. 32 Thiophosphoric esters containing P(S)(OR) groups give P(0)Cl groups with chlorine in a general reaction.233 All of the chlorobromophos-phonium ions [PCl,Br,-,]+ (0 < n < 4) have now been identified.234 Previous structural studies on hexafluorophosphoric acid hydrate appear to have been erroneous and the composition is now considered as H30+PF6-,HF,4H20.235 Arsenic.-Studies of the interaction of ASH, a strong catalyst poison with metal surfaces show ASH ASH, and ASH as surface species; oxidized films appear to give arsenic The C,As ring of 2,3,6-triphenylarsenin is planar.237 1-Arylarsoles (53) give firstly a radical anion with alkali metals and As I R (53) then give metal arsenides by cleavage of the R-As bond;238" the arsenic can be oxidized to arsenic(v) with chlorine (from PhICl ,) or h y p ~ c h l o r i t e .~ ~ ~ ' (4-Me2-NC,H,),M (M = As or Sb) are oxidized to blue Ar3M2+ cations with PhIC12.238c 230 V. A. Shokol and L. I. Molyavko J . Gen. Chem. (V.S.S.R) 1971,41 1412. 231 S. Fleming and R. W. Parry Inorg. Chem. 1972 11 1,2534. 232 D. H. Boa1 and G. A. Ozin J.C.S. Dalton 1972 1824. 233 W. Haubold and E. Fluck Z . anorg. Chem. 1972,392 59. 234 K. B. Dillon and P. N. Gates J.C.S. Chem. Comm. 1972 348. 2 3 5 D. W. Davidson and S. K. Garg Canad. J . Chem. 1972,50 3515. 2 3 6 I .M. Al-Daher and J. M. Saleh J . Phys. Chem. 1972 76 2851. 2 3 7 F. Sanz and J. J. Daly Angew. Chem. Internat. Edn. 1972,11 630. 2 3 8 ( a ) G. Markl and H. Hauptmann Angew. Chem. Internat. Edn. 1972 11 439; (b) G. Markl and H. Hauptmann ibid. p. 441 ; (c) J.-M. Keck and G. Klar Z . Naturforsch., 1972,27b 591 596 246 D. W. A . Sharp M. G. H . Wallbridge and J. H . Holloway The barrier to inversion in arsenic compounds is appreciably greater than that in ph~sphines.~~’ Organoarsenic azides are formed from other halides and lithium a~ides.’~~‘ There is some spectroscopic evidence for association of these compounds probably through bridging azide Sulphur silylimides react with organo-arsenic halides to give heterocyclic compounds e.g. (54), containing As S and N.241 Tetramethyldiarsenic disulphide in solution under-goes the equilibrium Me,AsSSAsMe 2 Me,As(S)SAsMe, although in the solid state the AsV-As”’ structure is stabilized ;242a Ph,As,S is a ring compound with a non-planar AsSAsSS ring.242b Dithioarsenates e.g.M~,AsS,M,~~ (from hydrogen sulphide and sodium cacodylate) and P ~ A s S M ~ ~ (from Ph2As02K and hydrogen sulphide) form salts with most metals. Me,NAsCl is present as the trans-form at room temperature but is partially converted into a second isomer probably the gauche-form at lower tempera-t u r e ~ ~ ~ ~ (see p. 232 ref. 140). AsOCl and As40sC1 are formed in the AsCl,,As,O, system.246 Ca(H,AsO,) contains symmetrical hydrogen bonds.247 The arsenite complex of dithiothreitol(55) has a pyramidal arsenic atom common to three rings (56).248 Vrbaite H ~ T ~ A S ~ S ~ S ~ contains As2SbSs chains and Hg3As4S sheets ;249 it is the first material to contain mixed (As Sb) chains.-CH,SH :*:: CH,SH S - 4 0 H Ai0> ‘S 239 G. H. Senkler jun. and K. Mislow J. Amer. Chem. SOC. 1972 94 291. 2 4 0 ( a ) D. M. Revitt and D. B. Sowerby J.C.S. Dalton 1972,847; (b) W. Beck W. Becker, K. F. Chew W. Derbyshire N. Logan D. M. Revitt and D. B. Sowerby ibid. p. 245. 2 4 1 0. J. Scherer and R. Wies Angew. Chem. Internal. Edn. 1971 10 812; 1972 11 529. 2 4 2 ( a ) R. A. Zingaro K. J. Irgolic D. H. O’Brien and L. J. Edmonson jun. J. Amer. Chem. Soc. 1971,93 5677; (b) A. W. Cordes P. D. Gwinup and M. C. Malmstrom, Inorg. Chem. 1972 11 836. 2 4 3 W. Kuchen M. Foster H. Hertel and B.Hohn Chem. Ber. 1972 105 3310. 2 4 4 A. Miiller and P. Werle Chem. Ber. 1971 104 3782. 2 4 5 J. R. Durig and J. M. Casper J. Mol. Structure 1971 10 427. 2 4 6 P. Flogel Z. anorg. Chem. 1972,389 188. 2 4 7 G . Ferraris D. W. Jones and J. Yerkess J.C.S. Chem. Comm. 1971 1568. 2 4 8 W. B. T. Cruse and M. N. G. James Acta Cryst. 1972 B28 1325. 2 4 9 M. Ohmasa and W. Nowacki Z. Krist. 1971 134 360 Thu Typical Elements 247 Antimony.-Sb-C bond cleavage occurs on treatment of alkylaryl-stibines with sodium; the reaction is useful for the subsequent formation of s t i b i n e ~ . ~ ~ ~ Bond cleavage also occurs when pentamethylantimony is treated with acids ; the resultant pseudohalides appear to be ionic but carboxylates seem to have chelat-ing carboxy-groups in the solid;250b Ph,BiNO and Ph4Bi02CC1 seem to be molecular solids.250' The compounds (Ph,SbN,),O and (Ph,BiC104)20 have metal-oxygen-metal bridges and trigonal-bipyramidal co-ordination about the metal; the previously described salts (R,M),0(C104) (M = Sb or Bi) all pre-sumably have comparable structures2 The halogeno-organo-antimony acetylacetonates have octahedral co-ordination about antimony in the solid state [the structures of MeSbCl,(a~ac)~~~" and P h S b C l ( a ~ a c ) ~ ~ ~ ~ have been determined] ; isomers are present in solution the various species presumably resulting from the relative co-ordination positions in the ~ctahedron.~ 2c Thermally stable R' Sb(OR2) compounds have been prepared by the sequence R',SbBr + Br -+ R',SbBr NaoR2 +RI2 Sb(OR2),; the compounds appear to be octahedral with bridging (methoxy) or chelating (OAc) Bisper-oxides Ph,Sb(OOR) are formed by the action of hydroperoxides on Ph,Sb.254 SbC14N is dimeric with bridging through one nitrogen of each of two linear azide The SbP molecule is present in the gas phase above heated mixtures containing the component elements.256 Dehydration of antimonic acid cannot be effected without some reduction of the metal and phases Sb6013 (with a defect pyrochlore structure) and /?-Sb204 are formed.257 Antimony pentachloride reacts with acid chlorides to give either ionic species involving chloride ion transfer to SbCl or co-ordination compounds involving 0 -+ Sb bonding.Structures describing these types of interaction include p-CH3-C6H4. COCl,SbCl (two forms one ionic and one m01ecular),~~~" CH,COCl,SbCI ,258b ( a ) S.-I.Sato Y . Matsumura and R. Okawara Inorg. Nuclear Chem. Letters. 1972, 8 847; J. Organometallic Chem. 1972 43 333; ( b ) H. Schmidbaur K.-H. Mitschke, J. Weidlein and S . Cradock Z . anorg. Chem. 197 1 386 139 ; H. Schmidbaur K.-H. Mitschke and J. Weidlein ibid. p. 147; ( c ) R. E. Beaumont and R. G. Goel Inorg. Nuclear Chem. Letters 1972 8 989. G. Ferguson R. G. Goel F. C. March D. R. Ridley and H. S. Prasad J.C.S. Chem. Comm. 1971 1547; R. G . Goel and H. S. Prasad Inorg. Chem. 1972 11 2141; J . Organometallic Chem. 1972 36 323. 2 5 2 ( a ) N. Kanehisa Y . Kai and N. Kasai Inorg. Nuclear Chem. Letters 1972 8 375; ( b ) K. Onuma Y. Kai and N. Kasai ibid. p. 143; ( c ) H. A. Meinema and J. G.Noltes, J. Organornetallic Chem. 1972,37 C3 1 ; H. A. Meinema A. Mackor and J. G. Noltes, ibid. #. 285; N. Nishii and R. Okawara ibid. 1972 38 335. 2 5 1 2 5 3 H. A. Meinema and J. G. Noltes J . Organometallic Chem. 1972 36 313. 2 5 4 G . A. Razuvaev T. G. Brilkina E. V. Krasilnikova T. I. Zinovjeva and A. I. Filimonov, 2 5 5 2 5 6 J. Kordis and K. A. Gingerich J . Phys. Chem. 1972,76 2336. 2 5 7 D. J. Stewart 0. Knop C. Ayasse and F. W. D. Woodhams Canad. J . Chem. 1972, 50 690. 2 5 8 ( a ) B. Chevrier J.-M. Le Carpentier and R. Weiss J . Amer. Chem. SOC. 1972 94, 5718; ( b ) J.-M. Le Carpentier and R. Weiss Acta Cryst. 1972 B28 1421 ; ( c ) J.-M. Le Carpentier and R. Weiss ibid. p. 1430; ( d ) B. Chevrier J.-M. Le Carpentier and R. Weiss ibid. p. 2673; ( e ) B.Chevrier J.-M. Le Carpentier and R. Weiss ibid. p. 2667; (f) J.-M. Le Carpentier and R. Weiss ibid. p. 1442; (8) H. Kietaibl H. Vollenkle, and A. Wittmann Monatsh. 1972 103 1360. J. Organometallic Chem. 1972 40 15 1 . U. Miiller Z . anorg. Chem. 1972 388,207 248 D. W. A . Sharp M. G. H. Wallbridge and J. H . Holloway (CH,),CHCOCl,SbCl ,258c and o-CH ,.C6H,-COC1,SbCl 258d (all ionic), PhCOCl,SbCl, m-CH,.C,H,.COCl,SbCl (CH2COC1)2,2SbC1,258J and C,Cl,O,CO,SbCl 58g (all molecular). K2Sb,S7 contains flat SbS pyramids and polymeric four-co-ordinate units based on trigonal-bipyramidal co-ordination with an equatorial lone pair and polymerization through the axial sulphur atoms.,, Dithiolate complexes of antimony(rI1) and bismuth(Ir1) are readily formed ; the bismuth complexes are dimeric probably with dithiolate bridges.,,’ Trimeric and dimeric species are observed by mass spectroscopy over antimony pentafluoride.26’ An accurate structure determination on (NH4)2SbF shows square-pyramidal anions ;262n the anion in CsSb2F7 consists of two trigonal bipyramids (each having an equatorial lone pair) joined by an axial bridge.,,,’ SbCl,F is ionic having the structure [SbCl,] [F,ClSbFSbClF,] ;263u Sb,Cl,F, (from an SbC1,-SbF melt) is [SbCl,] [Sb2F 1].263b a-Cs,Sb,Cl is similar to the corresponding arsenic chloride and contains SbC1 pyramidal molecules and chloride ions.264 Chlorobromoantimonates(v) are readily formed e.g. Et,NBr and SbCl gives Et,NSbC15Br.265 [Me,N],Sb,Br contains Sb,Br,,- anions bridged by Br molecules; each Sb,Br unit consists of two SbBr octahedra sharing a face.,,, Bismuth.-KBiO has chain anions ~[Bi0,,,0,,,].267 Co-ordination arrange-ments about bismuth are frequently complex.Bis-( 1-oxopyridine-2-thio1ato)-phenylbismuth(II1) has square-pyramidal co-ordination with the lone pair presumably occupying the position trans to the phenyl group.268a In trichlorotris-(3-sulphanilamido-6-methoxypyridazine)bismuth(111) co-ordination is from three chlorines three nitrogens and three oxygens and the position of the lone pair is not obvious.268b A new phase LiBiSe is formed by direct reaction of the component elements Bi,In,S contains six- and seven-co-ordinate bismuth, and the indium atoms are in octahedral ~o-ordination.~~~’ MBi,Te (M = Pb, Sn or Ge) SnBi,Te, and SnSb,Te have layer lattices.269c Bismuth trichloride also has a complex co-ordination sphere about bismuth consisting of a distorted 2 5 9 H.A. Graf and H. Schafer Z . Naturjorsch. 1972 27b 735. 2 6 0 G. Hunter J.C.S. Dalton 1972 1496. 2 h 1 M. J. Vasile and W. E. Falconer Inorg. Chem. 1972 11 2282. ( a ) R. R. Ryan and D. T. Cromer Inorg. Chem. 1972 11 2322; ( 6 ) R. R. Ryan, S. H. Mastin and A. C. Larson ibid. p. 2793. 2 h 3 ( a ) H. Preiss Z . anorg. Chem. 1972 389 254; (6) H . B. Miller H. W. Baird C. L. Bramlett and W. K. Templeton J.C.S. Chem. Comm. 1972 262. 2 6 4 K. Kihara and T. Sudo Z . Krist. 1971 134 142. 2 6 5 C. J . Adams and A. J . Downs J. fnorg. Nuclear Chem. 1972,34 1829; F. F. Bentley, 2 h 6 C. R. Hubbard and R. A. Jacobson Inorg. Chem. 1972 11 2247.2 6 7 B. Schwedes and R. Hoppe Z . anorg. Chem. 1972,392 97. 2 6 8 ( a ) J. D. Curry and R. J. Jandacek J.C.S. Dalton 1972 1120; (6) M. B. Ferrari, L. C. Capacchi L. Cavalca and G. F. Gasparri Acta Cryst. 1972 B28 1169. 2 6 9 ( a ) S . I . Berul’ V. B. Lazarev and A. V. Salov Russ. J . Inorg. Chem. 1971 16 1779; (bJ G. Chapius C. Gnehm and V. Kramer Acta Cryst. 1972 B28 3128; ( c ) T. B. Zhukova and A. I. Zaslavskii Soviet Phys. Cryst. 1972 16 796. 2 6 2 A. Finch P. N. Gates and F. J . Ryan fnorg. Chem. 1972 11 413 The Typical Elements 249 trigonal pyramid with bridging to five other chlorine atoms ;270a the geometry about bismuth in Cs2NaBiC1 appears to be Part 111 Groups VI-VIII 1 GroupVI Oxygen.-Useful reviews concerning observed and predicted spectral data for 02 Oz- 02+ and OtZ+,la polycations of Group VI,Ib oxygen fluorides and dioxygenyl compounds l C complexes of oxygen,' and complexes of oxygen-containing ligands ' have been published.The kinetics of the reactions 0 + 0 -+ 2OZ2" and 0 + NOZ -P NO + 0,2b have been studied. The second investigation illustrated the value of atomic resonance fluorescence spectrometry for determining rate constants of rapid atom + molecule bimolecular reactions. The existence of 02- as well as doubly charged halogen Te and Bi anions has been dempstrated by magnetic and electric deflection methods., Electron affinities for oxygen4- and ozone4" have been measured. Because of the difficulties associated with such measurements there is a notably long history of oxygen electron-affinity determinations.The recently determined values vary only a little and there is good agreement for a lower limit of 0.45 & 0.1 eV.4d The reaction of molecular oxygen with ground-state sulphur atoms has been investigated in the vacuum-ultraviolet region'" and by the flash photolysis-resonance fluorescence technique which suggests that the S(3P) atom attacks the Oz(3C) molecule end-on to form SOO which then rapidly falls apart to give SO(,C) and O(3P).56 The photochemistry of atmospheric ozone has been reviewed.6 The ozonide ion (03-) obtained by X-ray irradiation of l70-enriched KClO, has been studied by e.s.r. and the 1 7 0 hyperfine splittings observed have been tentatively interpreted to indicate slight distortion of the molecule from C2r to C symmetry.'" "* ( a ) S .C . Nyburg G. A. Ozin and J. T. Szymanski Acta Cryst. 1971 B27 2298; ( 6 ) L. R. Morss and W. R. Robinson ibid. 1972 B28 653. ' ( a ) P. H . Krupenie f . Phys. Chem. Ref. Data 1972 1 423; ( b ) R. J. Gillespie and J. Passmore Accounts Chem. Res. 1971,4,413; see also R. J. Gillespie and J. Passmore, Chem. in Britain 1972 8,475; (c) I. V. Nikitin and V. Ya. Rosolovskii Uspekhi Khim., 1971 40 1913; ( d ) J. A. McGinnety in 'MTP Internat. Rev. Sci. Inorg. Chem. Ser. One' 1972 5 229 ed. D. W. A. Sharp Butterworths London 1972; ( e ) S. M. Nelson, ibid. p. 175. (a) J. L. McCrumb and F. Kaufman f . Chern. Phys. 1972,57 1270; ( b ) M. A. A. Clyne and H. W. Cruse J.C.S. Faraday ZZ 1972 68 1281. K. Bethge Umschau 1972,72 23. (a) J. Berkowitz W.A. Chupka and D. Gutman f . Chem. Phys. 1971 55 2733; ( b ) R. J. Celotta R. A. Bennett J. L. Hall M. W. Siegel and J. Levine Phys. Reu. ( A ) , 1972 6 631; (cj S. J. Nalley and R. N. Compton Chem. Phys. Letters 1971 9 529; ( d ) T. 0. Tiernan B. M. Hughes and C. Lifshitz J . Chem. Phys. 1971,55 5692. ( a ) R. J. Donovan and D. J. Little Chem. Phys. Letters 1972 13,488; ( 6 ) D. D. Davis, R. B. Klemm and M. Pilling Internat. f . Chem. Kinetics 1972 4 367. H. U. Diitsch Adu. Geophys. 1971,15 219. Chem. Phys. Letters 1972 14 518. ' ( a ) S . Schlick f . Chem. Phys. 1972 56 654; ( b ) M. E. Jacox and D. E. Milligan 250 D. W. A . Sharp M. G. H . Wallbridge and J. H. Holloway A valence angle of 110 & 5" in 03- produced by the reaction of 0- with O2 in an argon matrix has been reported and absorptions near 1000 cm- ' have been attributed to trans-O,-." Evidence for the existence of bound-state dimers including (O,), has been reviewed and new insights into the nature of weak intermolecular interactions have been discussed.* HO, which is an important intermediate in many reaction systems in radiation chemistry photochemistry atmospheric chemistry and in combustion and other thermal reactions has been observed in the flash photolysis of H,O vapour and 0,-H mixture^.^" The molecular-modulation technique applied to C12-H,029b and i.r. studies of the radical produced by photolysing 0,-H,O or 0,-HCl mixturesgc have yielded values for H-0 = 96 pm 0-0 = 130 pm," andLHOO = 105 5°.9b9c The nature of inorganic peroxides in general has been reviewed." The first volume of what promises to be an excellent four-volume treatise on water has appeared."" In a brief review on the distribution of electronic charge in the H,O molecule electronegativity ionization potentials electron affinities, 'all-atom' valence-bond resonance structures and the electronic charge distribu-tion on the 0 atoms in OF, Li,O and Cs,O have been discussed."b There has been controversy over the interpretation of near-infrared spectra of water-acetone solutions.'20~ It has been again suggested that the structure of the hydrogen-bonded water dimer in CC1 solutions is linearlZc and the symmetrical cyclic structure suggested earlier' 2 d v e represents a transition state for interconversion of the linear structure.Ab initio LCAO-MO-SCF calcula-tions performed on the pairs of mixed dimers NH,OH-H,O and HOF-H,O show that they have the equilibrium open-chain structure.' 2f Because of apparent inadequacies of the corrected liquid-drop model which, in addition to applying bulk properties to small clusters predicts nucleation rates that can be 10' times larger than experimental values a molecular model applic-able to prenucleation water clusters has been described and applied to water clusters with clathrate-like structures composed of five-membered rings.' 3a The water-cluster formation rates of NO + ' 3b and H 3 0 + ' 3c ions and the kinetics and G.E. Ewing Angew. Chem. Internat. Edn. 1972 11 486. (a) C. J. Hochanadel J. A. Ghormley and P. J. Ogren J. Chem. Phys. 1972,56,4426; ( b ) T.T. Paukert and H. S. Johnston ibid. p. 2824; (c) M. E. Jacox and D. E. Milligan, J . Mol. Spectroscopy 1972,42 495. ( a ) 'Water a Comprehensive Treatise Vol. 1 The Physics and Physical Chemistry of Water' ed. F. Franks Plenum Press New York 1972; (6) J. F. Liebman J . Chem. Educ. 1972,49 415. ( a ) A. Burneau and J. Corset J . Phys. Chem. 1972,76 449; (6) S. Subramanian and H. F. Fisher ibid. p. 452; ( c ) P. W. Atkins and M. C. R. Symons Mof. Phys. 1972, 23 831; ( d ) L. B. Magnusson J . Phys. Chem. 1970 74 4221; ( e ) L. B. Magnusson, Mol. Phys. 1971 21 571 ; (f) J. E. Del Bene J . Chem. Phys. 1972,57 1899. l 3 (a) P. L. M. Plummer and B. N . Hale J . Chem. Phys. 1972,56,4329; ( 6 ) C. J. Howard, H. W. Rundle and F. Kaufman ibid. 1971 55 4772; (c) C.E. Young and W. E. Falconer ibid. 1972 57 918; ( d ) C. J. Howard V. M. Bierbaum and H. W. Rundle, ibid. p. 3491. l o I. I. Vol'nov Uspekhi Khim. 1972 41 600 The Typical Elements 25 1 mechanism of the formation of water clusters from 02+ and H 2 0 have been studied.' 3d Novel approaches to water structure seem to have been made last year14a and current water structure models were reviewed in the latter half of the year.14b The most recent significant theoretical examination concludes that water is best described in terms of a continuum or interstitial model.'& The results of an attempt to estimate the extent of 'superstructuring' of liquid water on addition of non-electrolyte lead to the ordering and change in spectral properties of not less than 4000 molecules of water.' New data on the possibility of there being free OH groups in liquid water have shown that in spite of the complexity of the overtone regions of the spec-trum vibrational overtones do provide evidence of such groups.'6" Spectral features in the Raman spectra for water and its deuteriated analogues have been described in terms of vibrational stretching modes of two types of hydrogen-bonded water molecules the fully bonded four-co-ordinated species and the three-co-ordinated type which also has a free OH.16b The last few months of 1971 saw a spate of papers on anomalous water but few have appeared since.Reviews concentrated on the history of the pheno-menon.' 7od Theoreticians at first anxious to predict likely structures for 'polywater' are now explaining why it does not exist.'8u*b Therm~dynamic'~".~ and kinetic studies20 have confirmed that the phenomenon should be attributed to the condensation or adsorption of water on soluble impurities and ionic mobility studies have led to the conclusion that there are no significant structural anomalies in water near the solid boundaries in microcapillaries.2 ' These results have again been further supported by many observations of appreciable amounts of silica compounds,22"-S NaOH and NaC02H,23 or other organic contami-l 4 ( a ) D.W. A. Sharp M. G. H. Wallbridge and J. H. Holloway Ann. Reports 1971, 68 A 377; ( b ) I. Eliezer and P. Krindel Coordination Chem. Rev. 1971 6 217; (c) T. R. Chay and H. S. Frank J . Chem. Phys. 1972,57,2910. A. P. Zhukovskii and A.I. Sidorova Zhur. strukt. Khim. 1971 12 534. l 6 ( a ) J.-J. Peron C. Bourderon and C. Sandorfy Canad. J. Chem. 1971 49 3901; ( b ) W. F. Murphy and H. J. Bernstein J . Phys. Chem. 1972,76 1147. ' ( a ) L. C . Allen J. Colloid Interface Sci. 1971,36,554; (b) M . Herberhold Chem. Unserer Zeit 1971 5 154; ( c ) D. H . Everett Chem. Tech. (Amsterdam) 1971 26 311; ( d ) D. H. Everett J. M. Haynes and P. J. McElroy Sci. Progr. (London) 1971 235 279. ( a ) L. C. Allen and P. A. Kollman J. Colloid Interface Sci. 1971,36,469; ( 6 ) L. C. Allen and P. A. Kollman Nature 1971 233 550. l 9 (a) D. H. Everett J. M. Haynes and P. J. McElroy J . Colloid Interface Sci. 1971, 36 483; ( b ) D. H. Everett and P. J. McElroy ibid. p. 529. 'O E. H. Taylor J. Colloid Interface Sci.1971 36 543. J. L. Anderson and J. A. Quin J.C.S. Faraday I 1972,68 744. 2 2 ( a ) V. I. Spitsyn M. P. Glazunov V. M. Mulyar B. V. Deryagin N. V. Churaev and Z. M. Zorin Doklady Akad. Nauk S.S.S.R. 1972 202 132; ( b ) B. F. Howell and J. Lancaster J. Colloid Interface Sci. 1972,38,633; ( c ) M. P. Gingold Nature Phys. Sci., 1972 235 75; ( d ) M. Prigogine and J. J. Fripiat Bull. SOC. chim. France 1971 12, 4291; ( e ) M. Prigogine and J. J. Fripiat Chem. Phys. Letters 1971 12 107; ( f ) W. D. Bascom J . Phys. Chem. 1972,76,456. 23 S . Suzuki Vu Hai and B. Vodar J. Chim. phys. 1971,68 1385 252 D. W. A. Sharp M. G. H . Wallbridge and J. H. Holloway nant~.,~"' An X-ray diffraction study has provided evidence for a polycrystalline material obtained from an anomalous water sample but does not identify the material.25 Some workers,26avb notably Deryagin and Churaev,26a still maintain that anomalous water is a solution of a less volatile component 'Water II' in ordinary water.A crystal structure of picrylsulphonic acid tetrahydrate has shown that H 5 0 2 + ions water molecules and sulphonate groups are bonded together to form layers in the structure. The 0-0 distance in H,02+ is 242.9(2) pm.27a 1.r. and Raman studies of crystalline HC1,2H,O have also confirmed the occurrence of the H 5 0 2 + ion and fundamental vibrations have been assigned.," Hypofluorous acid HOF discovered last year has been the subject of n.m.r.'*O and i.r.28b,c investigations. The Raman spectrum of 04F2 was obtained by photolysing a 3 l(v/v) solution of OF in liquid oxygen at 90 K.29a No Raman evidence of 0,F radicals was found though e.s.r.signals due to the radical had been observed several years ago.29b Reactions of O,F and O,F with SO2 yield principally F,SO, with smaller amounts of F2S205 and FS0,OOF. The FS0,OOF results from an OOF intermediate and 04F2 provides the better source of OOF.29' Studies of the reaction H + OF * HFS + OF in the microwave cavity of an e.s.r. spectrometer have provided a value of 2.52 eV (243 kJ mol-') for the binding energy of OF.30a New mass spectrometric investigations of the OF radical30b,' have established a rate constant k = 1.7 x 1013 exp( -E/RT) cm3 mol- ' for the reaction3'' and a dissociation energy of Doo (0-F) = 2.2 eV (215 kJ mol-').30' Argon-matrix Raman spectra of OF and have confirmed earlier i.r.work and Raman and i.r. data for crystal-line OF indicate that the solid is not centrosymmetric and contains at least two molecules per primitive cell on sites of symmetry C or C,.31b A continuous 2 4 ( a ) S . B. Brummer J. I. Bradspies G. Entine C. Leung and H. Lingertat J . Phys. Chem. 1972,76,457; ( 6 ) R. J. Jakobsen U.S. Nat. Tech. Inform. Serv. AD Rep. 1972, No. 737309 [Gout. Rep. Announce. (U.S.) 1972 72 no. 7 p. 661; (c) D. L. Rousseau, J . Colloid Interface Sci. 1971 36 434; ( d ) E. R. Lippincott J. M. Casper and P. Schuhmann U.S. Nat. Tech. Inform. Serv. AD Rep. 1972 No. 739673 [Gout. Rep. Announce. (U.S.) 1972 72 no. 10 p. 691. 2 5 G. A. Petsko and W. R. Massey jun. J . Colloid Interface Sci. 1971 36 508. 2 6 ( a ) B.V. Deryagin and N. V. Churaev J . Colloid Interface Sci. 1971 36 415; ( 6 ) T. F. Page jun. and R. J. Jakobsen ibid. p.427. " ( a ) J . 0. Lundgren Acta Cryst. 1972 B28 1684; (6) J. Roziere and J. Potier J . Mol. Structure 1972 13 91. (a) J. C. Hindman A. Svirmickas and E. H. Appelman J . Chem. Phys. 1972 57, 4542; ( b ) E. H. Appelman and H. Kim ibid. p. 3272; (c) E. F. Pearson and H. Kim, ibid. p. 4230. 2 9 (a) D . J. Gardiner and J. J. Turner J . Fluorine Chem. 1972,1 373; (6) N. J. Lawrence, J. S. Ogden and J. J. Turner J . Chem. SOC. ( A ) 1968 3100; (c) I. J. Solomon and A. J. Kacmarek J . Fluorine Chem. 1971 1 255. 30 ( a ) D. H. Levy J . Chem. Phys. 1972 56 1415; (6) H. G . Wagner C. Zetsch and J. Warnatz Ber. Bunsengesellschaft phys. Chem. 1972 76 526; (c) M.A. A. Clyne and R. T. Watson Chem. Phys. Letters 1971 12 344. ( a ) L. Andrews J . Chem. Phys. 1972 57 5 1 ; ( 6 ) J. Tremblay and R. Savoie Canad. J . Chem. 1971,49 3785 The Typical Elements 253 preparation of OF from elemental fluorine and alkali-metal hydroxide in a spray-nozzle tube-reactor has been de~cribed.~ Several kinetic studies on OF reactions have been carried out. Pyrolysis gives rise to only 0 and F, and a radical chain mechanism has been proposed for the slightly-less-than-first-order reaction.33u The kinetics of the hydrolysis of dissolved OF (OF + 20H- + 0 + 2F- + H20),33b the reaction 20F + 3H --+ 4HF + H,O + 0.502,33" and the reaction of COF with OF in the presence of CsF'Ob have been studied. Irradiation of a gaseous mixture of OF and ClF in a quartz flask gives [C10F2]2[SiF6].34 The dissociation of this compound provides another route to the new compound ClOF (see Group VII).Sulphur .-Molecular orbital calculations on SO,'- 35a4 SO ,35d*e S0,F2, S0,Cl,,35c H2S,3se,J H2S02,35J CS2,35e and SF635g have furthered the debate concerning d-orbital participation in the bonding. The involvement of 3d orbitals in the bonding of dialkyl sulphoxides (R2SO)36a and dialkyl sulphones (R,S0,),36b and their derivatives has also been discussed. Quadrupole moments calculated by the CNDO method for Me,& SO, thiophen and SO,F agree better with experimental values when 3d orbital polarization functions are included.37 Neutral S (x = 2 4 ) S,- S3- and S,- have all been proposed as species which might account for the blue colour which develops when sulphur is heated with water in the presence of a basic salt or when sulphur is dissolved in molten alkali metals or alkali-metal polysulphides in basic solvents.New spectroscopic, conductivity and magnetic susceptibility measurements suggest that the species is in fact the S3- radical anion.38 New studies have shown that the configuration of the SS2+ cation is that of a folded ring,39" similar to that of the SeS2+ ion reported earlier.39b Absorption 32 K. H. Hellberg and J. Massonne Ger. Offen. 2 026 9 17/ 197 1 . 3 3 (a) T. J. Houser and T. W. Asmus J. Amer. Chem. Soc. 1972,94,3326; ( 6 ) S. N. Misra and G. H. Cady Inorg. Chem. 1972 11 1132; (c) T. W. Asmus and T. J. Houser, ibid. p. 234. 3 4 K. Zuchner and 0.Glemser Angew. Chem. Internat. Edn. 1972 11 1094. 3 5 (a) U. Gelius B. Roos and P. Siegbahn Theor. Chim. Acta 1971 23 59; ( 6 ) K. H. Johnson and F. C. Smith Internat. J . Quantum Chem. Symp. 1971 5. 429; (c) M. F. Guest and I. H. Hillier Internat. J. Quantum Chem. 1972,6,967; see also R. L. DeKock, D. R. Lloyd I. H. Hillier and V. R. Saunders Proc. Roy. Soc. 1972 A328 401; ( d ) M. F. Guest I. H. Hillier and V. R. Saunders J.C.S. Faraday 11 1972 68 114; ( e ) M. S. Nakhmanson V. I . Baranovskii and A. I. Panin Vestnik Leningrad. Uniu. (Fiz. Khim.) 1972 2 35; (f) J. R. Van Wazer and I. Absar Adv. Chem. Ser. 1972 110, 20; ( g ) F. A. Gianturco C. Guidotti U. Lamanna and R. Moccia Chem. Phys. Letters, 197 1 10 269. 3 6 ( a ) H. Bock and B. Solouki Angew.Chem. Internat. Edn. 1972,11,436; ( 6 ) B. Solouki, H. Bock and R. Appel ibid. p. 927. 3' H. L. Hase and A. Schweig Chem. Phys. Letters 1971 12 238. 3 8 T. Chivers and I. Drummond Inorg. Chem. 1972 11 2525. 39 (a) C. G. Davies R. J. Gillespie J. J. Park and J. Passmore Inorg. Chem. 1971 10, 2781; ( b ) R. K. McMullan D. J. Prince and J. D. Corbett ibid. p. 1749; ( c ) R. J. Gillespie and P. K. Ummat ibid. 1972 11 167; ( d ) R. A. Beaudet and P. J. Stephens, Chem. Comm. 1971,1083; ( e ) M. C. R. Symons and J. G. Wilkinson Nature Phys. Sci., 1972 236 126; (f) M. Herlem A. Thiebault and G. Adhami Analyt Letters 1972, 5 309 254 D. W. A . Sharp M . 6. H. Wallbridge and J . H . Holloway and e.s.r. spectra together with cryoscopic measurements have shown that solutions of sulphur in oleum are successively oxidized to S162+ Sg2+ s42+, and SO with time or increasing SO concentration.It appears from e.s.r. data that equilibria exist between Slb2+ and s8+ and between Ss2+ and S42+.39c Independent e.s.r. work supports an earlier proposal39d that the paramagnetic cation in solutions of oleum is S,+ formed by the oxidation of S8.,'= The ions S2+ S+ S2+ and S4+ have been observed in HS0,F-sulphur mixtures.39f The cation SA2 + is included in a general theory for clusters and ring compounds in which rules for explaining and predicting the geometries of electron-precise or -rich polynuclear aggregates on the basis of the number of skeletal electron pairs have been o~tlined.~' The existence of S and S in sulphur vapour at intermediate temperature and pressure has been recognized for several years.Assignment of the visible spectra of the two species has now been made and the characteristic absorptions found in hot liquid sulphur and trapped liquid ~ulphur.~' The polyatomic sulphur-chain compound diethyl 1,1-(cycloheptasulphanyl)hydrazine-2,2-dicarboxylate (57) has been prepared by the reaction of S7C12 with H,NN(CO,Et) in Et20 in the presence of Et3N.42a An X-ray structure determination of the third isomer of S6(NH) has shown that it is cyclohexasulphur-l,3-di-imide (58) rather than cyclohexasulphur-1,2-di-imide.42b Heptasulphur imide S7NH reacts with di-borane in an analogous way to reactions with BCl and BBr to give S,NBH .42c Cyclo-octasulphur oxide S 8 0 (59 ; n = 7) has been synthesized by means of the \ \ / NN(C0 Et)2 /s-s-s S s-s-s-(57) (58) The pseudo mirror plane of the molecule is given by m C1 H / \ \ / O=S + S -+ S + 1 0 + 2HC1 C1 H (59) 40 D.M. P. Mingos Nature Phys. Sci. 1972 236 99. 4 1 B. Meyer T. Stroyer-Hansen and T. V. Oommen J . MoI. Spectroscopy 1972,42,335. 4 2 ( a ) K. H. Linke and D. Skupin 2. Nuturforsch 1971 26b 1371; (b) H. J. Postma, F. Van Bolvil and A! Vos Acta Cryst. 1971 B27 2480; ( c ) M. H. Mendelsohn and W. L. Jolly Inorg. Chem. 1972 11 1944; (d) R. Steudel and M. Rebsch Angew. Chem. Internat. Edn. 1972 11 302; (e) H. G. Heal M. S. Shahid and H. Garcia-Fernandez J. Chem. SOC. ( A ) 1971 3846 The Typical Elements 255 well-known ring-closure reaction using crude sulphane. This is the first compound of the class which can be obtained in the pure state and the structure is probably that of a zig-zag S ring with an equatorial or axial 0 atom.42d Attempts to make S,N2 (60) and S13N2 (61) by coupling 1,3-hexasulphur di-imide with S S s-s / \ / \ / \ S N-S S N S I S I I I I I s s s s s I S I I I I I S N S N-S \ / \ / \ / S S s-s (60) (61) S3C12 or S,Cl respectively have failed.42' Pseudo single crystals of (SN) are obtained by the polymerization of S,N2 at liquid-nitrogen temperature., The first oxide of the S4N4 ring (62) has recently been isolated from the reaction of NN'-bis(trimethy1silyl)sulphur di-imide with the anhydride of fluorosulphuric acid.44a Tetrathiazyl tetra[bis(trifluoromethyl) 2 Me,Si-N=S=N-SiMe + 2 FS0,-0-S0,F + O N N O 0 / \ N N \ / \ / \ / S S + 2 Me,SiF + 2 Me,SiOSO,F NS/ (62) nitroxide] N,S,[ON(CF,),], has been prepared by the reaction of S,N4, N4S4H4 or N,S,Cl with liquid (CF,),NO*.The same white crystalline solid can also be obtained by the reaction of N3S,C1 with Hg[ON(CF,),] .44b The reaction of S,N4 with SOC1 in the presence of iron(u1) or aluminium chloride has yielded mixtures of tetrachlorometallates of the cations S,N,Cl+ S,N + , and S5N5+.44c The salts S5N5+A- (A = AlCI, FeCl, or SbCI,) can also be readily prepared in high yield from S4N4 (NSCl), and the metal Simple 1 1 adducts of S4N with aluminium chloride or bromide have also been obtained and the reaction of the AlCI adduct with SbC1 has been described.,,' Sulphur-nitrogen-halogen compounds have been briefly reviewed45a and methods of preparation properties and derivatives of some sulphanuric com-4 3 M.Boudeulle A. Douillard P. Michel and G. Vallet Comp. rend 1971 272 C 2137. *' ( a ) H. W. Roesky and 0. Petersen Angew. Chem. Internat. Edn. 1972 11 918; (b) H. J. Emeltus and R. J. Poulet J. Fluorine Chem. 1971 1 1 3 ; (c) A. J. Banister and P. J. Dainty J . C.S. Dalton 1972,2658; ( d ) A. J. Banister and P. J. Dainty ibid. p. 2661 ; (e) C. H. Chan and F. P. Olsen Znorg. Chem. 1972 11 2836 256 D. W. A . Sharp M . G. H. Wallbridge and J. H. Holloway pounds have been described.45b Heats of fusion and decomposition have been obtained for (SNOX) and S,N,O,XPh (X = F or C1) using a differential scanning calorimeter.45c An X-ray crystal-structure determination on N,S,F has shown a six-membered ring of alternating S and N atoms with a chair conformation.All the S-N bond lengths are equal through delocalized d,-p bonds in keeping with other halogeno- and oxohalogeno-cyclothiazenes.46 Microwave examination of NSCl has provided force constants and a value for the dipole moment.47" It has been shown that the action of SO,Cl (rather than Cl,) on S4N4 or S3N2Cl+C1-provides a better route to the formation of (NSCl) .47b Derivatives of thiotrithiazyl chloride of the types S,N,X and S,N,O,SMe,-H0,SMe have been obtained by the reaction of S4N3Cl with HX [X = O,SMe, O,SCF N(SO,F) N(SO,CF,)SO,Cl or N(S02CF3)S02F].47C A new poly-mer S,,N,CI, has been claimed to result from the thermal reaction between sulphur and nitrogen in the presence of urea.47d Reviews on binary and ternary sulphur-containing systems including S-0, S-SO S-H,S S-Se and S-I,48" and little-known and non-commercial uses of SO ,48b have been published.Phase equilibrium studies on the SO,-quinol clathrate indicate that aqueous quinol solutions may be of value as SO absor-b a n t ~ . ~ ~ Ab initio MO-SCF-LCAO calculations have been performed on SO,, SO,- and SO,,- in an attempt to provide information about the electronic changes which occur when SO co-ordinates to transition-metal and the first complex in which SO alone bridges two metal atoms has been synthesized and unambiguously characterized as (63) by X-ray diffraction. The material was separated chromatographically from the products of reaction of SO with .n-C,H,Fe(CO),Na in tetrahydr~furan.,'~ An electron-diffraction investigation on SO is not in perfect agreement with the results from earlier spectroscopic work possibly on account of traces of S,O in the diffracting ~ a p o u r .~ ' Complexes of SO with acetyl and mono-chloroacetyl chlorides nitrosyl and nitryl chlorides phosphoryl chloride seleninyl 4 5 ( a ) 0. M. Glemser Internat. J. Sulfur Chem. (C) 1971 6 35; (b) T. Moeller and R. L. Dieck in 'Preparative Inorganic Reactions' ed. W. L. Jolly Wiley-Interscience New York 1971 vol. 6; (c) R. L. McKenney and N. R. Fetter J. Inorg. Nuclear Chem. 1972, 34 3569. 4 6 B. Krebs S. Pohl and 0. Glemser J.C.S. Chem. Comm. 1972 548. 4 7 (a) S. Mizumoto J. Izumi T. Beppu and E. Hirota Bull. Chem. Sac. Japan 1972, 45 786; (b) G.B. Alange A. J. Banister and B. Bell J.C.S. Dalton 1972 2399; ( c ) H. W. Roesky and M. Dietl Z . Naturforsch. 1971 26b 977; ( d ) S. Rajeswari Indian J . Chem. 1972 10 441. 4 8 ( a ) T. K. Wiewiorowski in 'MTP Internat. Rev. Sci. Inorg. Chem. Ser. One' 1972, 2 171 ed. C. C. Addison Butterworths London 1972; ( 6 ) R. Leclercq D. W. Bixby, and H. L. Fike Sulphur Inst. Tech. Buff. 1972 no. 19. 4 9 Y. Yokoyama and G. Konno Kagaku Kogaku 1972,36,629. '" (a) P. D. Dacre and M. Elder Theor. Chim. Acta 1972 25 254; (b) M. R. Churchill, B. G. Deboer K. L. Kalra P. Reich-Rohrwig and A. Wojcicki J.C.S. Chem. Comm., 1972,98 1 . 5 1 A. H. Clark and B. Beagley Trans. Faraday Soc. 1971,67,2216 The Typical Elements 257 chloride,52” and oxides of nitrogen52b have been prepared.Spectroscopic studies indicate that only the ClCH,COCl and SeOCl adducts are n o n - i ~ n i c . ~ ~ ” The rest contain anions such as S 2 0 7 2 - S3OIo2- and s401,~-. Reactions of SO, with K$407 and KB,O have given B2O,,SO, K2B402(S04) (64) and K2B,0(S04) .52c The chemistry of the fluorinated p-sultones (65) formed by K2 r 0 0 B- y \ /O\ B / \ / I I 0 0 0 0 0 II II 0 .o-s-the addition of SO to polyfluoro-olefins has been reviewed.52d New thermo-dynamic functions for a variety of oxygenated sulphur complex ions have been obtained from heat capacity and heat of solution measurement^.^^ The crystal structures of H2S04,4H,0 and its deuteriated analogue have shown that the structure consists of H502+ (cf. ref. 27b) and Sod2- ions hydrogen-5 2 ( a ) R.C . Paul C. L. Arora and K. C. Malhotra Zndian.J. Chem. 1972 10 92; (b) R. C. Paul C. L. Arora and K. C. Malhotra ibid. p. 94; (c.) S. N. Kondrat’ev and S. I. Mel’nikova Zhur. neorg. Khim. 1972 17 940; ( d ) I. L. Knunyants and G. A. Sokolski Angew. Chem. Internat. Edn. 1972,11 583. 5 3 J . W. Cobble H. P. Stephens I. R. McKinnon and E. F. Westrum jun. Znorg. Chem., 1972 1 1 1669 258 D. W. A . Sharp M . G . H. Wallbridge and J. H. Holloway bonded to each other in a three-dimensional network. All the S - 0 bonds in the SO,'- ion are eq~ivalent.~," Attempts have also been made to gain informa-tion on the liquid structure of 100% H2S04 from X-ray d i f f r a ~ t i o n ~ ~ ~ ~ ' and equilibrium compositions in sulphuric acid solutions have been studied by i.r.and Raman method^.^,^.^ Reactions in fluorosulphuric acid have continued to provoke interest. The reactions of some metal chlorides and organic and inorganic bases5'" and redox reactions with Br, Cl, IC1 and NOCl as oxidizing agents and P"' and As"' as reducing agents5 5b have been examined conductimetrically. Nitronium and nitrosyl fluorosulphates have been isolated from the reactions of oxides of nitrogen with fluorosulphuric acid and P z 0 5 forms a mixture of disulphuryl and tri-sulphuryl fluorides. Oxides of As Sb and Bi form fluorosulphates and SO gives pyrofluorosulphuric acid.5 5' However the earlier work which purported to have identified yellow Sb4,+ and blue Sbs2+ ionsssd has not been substantiated by recent work which clearly shows that colourless SbS0,F is formed and that the blueand yellowcoloursaredue to thereductionofthesolvent t ~ s u l p h u r c a t i o n s .~ ~ ~ Ionization energies and electron affinities have been calculated for SF SF,, SF, and SF in a molecular-orbital study of their binding energie~.~" Investiga-tions of ion-molecule reactions of S,F in the gas phase have shown sulphur-transfer reactions to dominate over fluorine-transfer reaction^.^ ' Raman and i.r. spectra of solid SF have revealed three distinct forms during annealing from liquid-nitrogen temperature.58a Pure F,SSF has been prepared by the reaction of SCl with KF in glass which has been conditioned with SF, and the stretching vibrations of the SF and SF groups have been assigned.58b Those of SF,', previously determined from the spectra of solids have been confirmed by Raman spectroscopic polarization measurements on solutions of SF +BF4- SF +PF6-, and SF,+AsF,- in anhydrous HF.58f A new radical S,Cl has been observed for the first time by e m .methods.59 The reaction of S2C1 with hydrazine in a 5 2 molar ratio in diethyl ether resulted in the oxidation of N2H4 to nitrogen and the reduction of S,Cl to sulphur. 5 4 (a) T. Kjallman and I. Olovsson Acta Crysr. 1972 B28 1692; (b) J. U. Weidner H. Geisenfelder and H. Zimmermann Ber. Bunsengesellschaftphys. Chem. 197 1,75,800; (c) J. U. Weidner H. Geisenfelder and H. Zimmermann ibid. 1972 76 628; (d) N. B. Librovich and V. D. Maiorov Doklady Akad. Nauk S.S.S.R. 1971 198 1371; ( e ) N. G. Zarakhani N. B. Librovich and M.I. Vinnik Zhur. fiz. Khim. 1971 45, 1733. 5 5 (a) R. C. Paul K. K. Paul and K. C. Malhotra J . Inorg. Nuclear Chem. 1972 34, 2523; (6) R. C. Paul S. K. Sharma K. K. Paul and K. C. Malhotra ibid. p. 2535; (c) R. C. Paul S. K. Sharma R. D. Sharma K. K. Paul and K. C. Malhotra ibid., 1971,33,2905; (d) R . C. Paul K. K. Paul and K. C. Malhotra Chem. Comm. 1970, 453; ( e ) R. J. Gillespie and 0. C. Vaidya J.C.S. Chem. Comm. 1972 40. 5 6 A. L. Companion Theor. Chim. Acta 1972,25,268. 5 7 K. P. Wanczek K. H. Lebert and H. Hartman 2. Naturforsch. 1972 27a 155. 5 8 ( a ) C. V. Berney J. Mol. Structure 1972 12 87; (6) F. See1 and R. Budenz J. Fluorine Chem. 1971 1 117; (c) M. Brownstein and J. Shamir Appl. Spectroscopy 1972 26, 77. 5 9 F. G. Herring C. A. McDowell and J.C. Tait J. Chem. Phys. 1972 57 4564 The Typical Elements 259 However the 1 1 reaction with MeNHNHMe produced a cyclic dihydrazide (66).60a With LiN=C(CF,) disulphur dichloride produced bis(hexafluoroiso-propylidenimino) disulphide [(CF,),C=N],S, which reacts further in two s-s / \ MeN NMe I I MeN s-s (66) \ /NMe different ways with C1 to give (CF,),CClN=S=NCCl(CF,) and (CF,),C= NSCl. This latter compound is readily attacked by compounds such as dimethyl-amine and NH to give substituted sulphenyl compounds by cleavage of the S-Cl bond.60b The reaction of SCl with Me,SiN=S=O in a nitrogen atmo-sphere has provided a new route to S(NSO) . The second product of the reaction, Me,SiCl proved to be an excellent solvent for S(NSO) .60c An attempt to assess the extent that MO calculations in conjunction with an approximate force field can be useful in confirming a set of vibrational assign-ments has been made using Raman data for SF,.61 Reaction of SF4 with LiN=C(CF,) (cf ref.60b) has resulted in the formation of five new compounds each of which arises indirectly from the reaction of the lithium salt on the sulphur difluoride imide.62a This contrasts with the predict-able metathesis reactions observed with other inorganic chlorides and fluorides.62b Although it is well known that Si(NCO) reacts slowly with SF to produce F2S=NC(0)F in good yield it has only recently been shown that if excess of Si(NCO) is used the reaction goes further to produce F,S=NC(0)NC0.62C Fluorine-18 exchange reactions between SF and Group I fluorides have been discussed in relation to the formation of SF,- as intermediate.63" Vibrational spectra of the CsF adducts of SF (and SeF,) indicate a close resemblance with those of the isoelectronic molecules ClF and BrF .This is indicative of square-pyramidal anions of C4" symmetry63b and is in close agreement with independent results published last year.63c Ionization energies of SF calculated by the multiple scattering method are in better agreement with recent X-ray photoelectron spectroscopic data than either ( a ) H. Lingmann and K. H. Linke 2. Naturforsch. 1971 26b 1207; (b) S. G. Metcalf and J. M. Shreeve Inorg. Chem. 1972,11 1631 ; (c) D. A. Armitage and A. W. Sinden, ibid. p. 1 1 5 1 . I. W. Levin J . Chem. Phys. 1971 55 5393. (a) R.F. Swindell and J. M. Shreeve J . Amer. Chem. SOC. 1972 94 5713; (6) R. F. Swindell D. P. Babb T. J. Ouellette and J. M. Shreeve Inorg. Chem. 1972 11 242; ( c ) A. F. Clifford J. S. Harman and C. A. McAuliffe Inorg. Nuclear Chem. Letters, 1972 8 567. ( a ) C. J. W. Fraser D. W. A. Sharp G. Webb and J. M. Winfield J.C.S. Dalton, 1972 2226; (b) K. 0. Christe E. C. Curtis C. J. Schack and D. Pilipovich Inorg. Chem. 1972,11 1679; ( c ) L. F. Drullinger and J. E. Griffiths Spectrochim. Acta 1971, 27A 1793 260 D. W. A . Sharp M . G. H . Wallbridge and J . H . Holloway ab initio (SCF-MO-LCAO) or semi-empirical (CNDO) results.64 Mass spectro-metric examination of POF,-SF and PSF3-SF6 mixtures has shown that the principal ion-molecule reaction involves the reaction of SF - with POF and PSF to give POF,- and PSF4- re~pectively.~ A patent on the preparation of SF,Cl by the interaction of ClF and SF in the presence of CsF in a Monel cylinder has appeared,66" and inferences about the chemical bonds in the molecule have been drawn from a stud; of the quadrupole hyperfine effects in the micro-wave spectrum.66b An electron-diffraction study of SF,NF gas has provided values for bond distances and angles in the Vibrational analyses of SOF SOCI ,67a SOBr 6 7 0 3 SO,F, S02C12,67c SO,FCI and S0,FBr67"-e have been carried out and the rotational spectra of S035C137C1 has been studied between 8000 and 80000 M H z .~ ~ ~ A microwave study of S0,CIF has provided new values for bond lengths and angles.68 An unusual structure with novel bonding has been proposed for S02C1 - from e.s.r.measurements. The structure is visualized as a radical-anion complex of SO and C1 in which the unpaired electron is associated with the lowest un-occupied orbitals of both molecule^.^^ 17+S03F- and a variety of previously known iodine species have been detected in the iodine-peroxydisulphuryl difluoride system.70a Oxyfluoro-sulphates of several and CeF,(S0,F)70b have been obtained in reactions of peroxydisulphuryl difluoride with the metal carbonates or oxides and CeF, respectively. The new compounds PCl,+SO,F- PC1,BrfSO,F-, PPh3C1+S03F- and PPh,Br+SO,F- have been isolated from fluorosulphuric acid High-purity SOF has been prepared almost quantitatively by the reaction of SOF with BrF ;it was also prepared from SOF and ClF .'la Monosubstituted derivatives of thionyl tetrafluoride have been obtained from the reaction between silylamines and SOF on many occasions and now it has been shown that silyl ethers also produce substitution and that in some cases 2 3 or 4 fluorines can be replaced.71b Reactions of OSF4 with AN(SiMe,) [A = Li or Na] in 1 1 and 1 2 molar ratios has given OSF,NSiMe and OS( NSiMe,) re~pectively.~ Electronic i.r.and Raman spectroscopy has been used to study XS0,- ions in halide-ion-SO mixtures. The vibrational spectra are consistent with the b4 J. W. D. Connolly and K. H. Johnson Chem. Phys. Letters 1971 10 616. 65 T. C. Rhyne and J . G. Dillard Internat. J . Mass Spectrometry Ion Phys. 1971,7 371. 6 6 ( a ) C. J . Schack and R. D. Wilson U.S.P. 3649222/1972; ( 6 ) K.S. R. Murty and A. K. Mohanty Indian J . Phys. 1971-72 44 635; ( c ) J. Haase H. Oberhammer, W. Zeil 0. Glemser and R. Mews Z . Naturforsch. 1971 26a 1333. 6 7 ( a ) R. A. Suthers and T. Henshall Z . anorg. Chem. 1972,388,269; (6) K. Ramaswamy and S. Jayaraman Indian J . Pure Appl. Phys. 1972 10 72; (c) R. A. Suthers and T. Henshall Z . anorg. Chem. 1972,388,257; (d) B. N. Cyvin and S. J. Cyvin Acra Chem. Scand. 1972 26 1284; ( e ) K. Ramaswamy and S. Jayaraman J . Mol. Structure 1971, 10 183; (f) A. Dubrulle and D. Boucher Compt. rend. 1972 274 B 1426. '* C. W. Holt and M. C. L. Gerry Chem. Phys. Letters 1971,9 621. 6 9 C. M. Kerr and F. Williams J . Amer. Chem. Soc. 1972 94 5212. 'O ( a ) C. Chungand G. H. Cady Inorg. Chem. 1972,11,2528; ( 6 ) R.Dev W. M. Johnson, and G. H. Cady ibid. p. 2259; (c) R. Dev and G. H. Cady ibid. 1971 10 2354. 7 1 ( a ) K. Seppelt Z . anorg. Chem. 1971 386 229; ( 6 ) D. S. Ross and D. W. A. Sharp, J.C.S. Dalton 1972 34; ( c ) 0. Glemser M. Feser S. P. Von Halasz and H. Saran, Inorg. Nuclear Chem. Letters 1972 8 321 The Typical Elements 26 1 expected (C,) geometry and it appears that the magnitude of the X-SO inter-action is in the order FS0,- > ClS0,- < BrS0,- < ISO,-?, Infrared and Raman spectra of Me,S Me,SO and Me,SO and their per-deuteriated analogues have been studied and their normal vibrations assigned.73 Calorimetric studies of water-dimethyl sulphoxide adducts in dioxan and enthalpies of transfer of halide ions in aqueous Me,SO have been made. A temperature-dependent equilibrium between Me2S0,2H,O and Me2S0,3H,0 has been proposed to correlate literature data on the Me,SO-H,O s ys tem.4c The first four-co-ordinated sulphur(1v) compound without halogen atom ligands Ph,S[OC(CF,),Ph] has recently been reported75" and an X-ray study has shown that the alkoxy-ligands occupy the apical positions of a trigonal bipyramid in the as was suggested by 19F n.m.r. data for the molecule in s ~ l u t i o n . ~ 5a The magnetic non-equivalence of the diastereotopic groups in alkylsulphinyl chlorides76"* and some new chlorosulphites76a has been demonstrated. The structure of diphenyl disulphone PhS(O)S(O)Ph has provided yet another example of a long S-S bond. Discussion of the theoretical implications suggests that the unusual length of these bonds in disulphides and oxy-disulphides have not been satisfactorily e~plained.~ Additionofnucleophilicreagents to sulphenes(R'R2C=S0,) has been regarded for some time as one of the most important reactions of these reactive inter-mediates.In an examination of reactions of sulphenes with tervalent phosphorus compounds PhCH,SO,X [X = C1 or OC,H,(N02),-o,p] reacted with a Ph,P-Et,N mixture to give PhCH,P+Ph,X- in each case. The mechanism PhCH-SO, can be explained in terms of a cyclic intermediate the zwitterions PhCH-CO,$Ph or PhCH-S02-.78a \ / or perhaps via PPh, / Sulphene-tertiary amine zwitterions (CHR1S0,kR2,) have been suggested as intermediates in the multi-exchange of hydrogen in the formation of sulphenes by the action of bases on alkanesulphonyl ~hlorides.~~' l 2 D.F. Burow Inorg. Chem. 1972,11 573. l 3 G . Geiseler and G. Hanschmann J . Mof. Structure 1972 11 283. l 4 ( a ) F. Rallo and F. Rodante Ann. Chim. (Italy) 1972 62 221 ; ( b ) R. Fuchs D. S. Plumlee,jun. and R. F. Rodewald Thermochim. Acto 1971 2 515; ( c ) E. A. Symons, Canad. J . Chem. 1971,49,3940. 75 ( a ) J. C. Martin and R. J. Arhart J . Amer. Chem. SOC. 1971 93 2341; ( 6 ) I. C. Paul, J. C. Martin and E. F. Perozzi ibid. p. 6674. l 6 ( a ) M. Mikolajczyk and J. Drabowicz 2. Naturforsch. 1971,26b 1372; ( b ) G. Canalini, G. Maccagnani and F. Taddei Tetrahedron Letters 1971 3035. l 7 C. Th. Kiers and A. Vos Rec. Trav. chim. 1972 91 126. '* ( a ) J. F. King E. G. Lewars and L. J. Danks Canad. J . Chem. 1972 50 866; ( 6 ) J.F. King E. A. Luinstra and D. R. K. Harding J . C . S . Chem. Comm. 1972 1313 262 D. W. A . Sharp M. G. H. Wallbridge and J. H. Holloway 0 moiety has received attention during the past few years. For example it is known that polymers containing the group are formed when SOF reacts with ammonia. The anal-ogous reaction using bis(perfluoroalky1)sulphur oxydifluorides has now been examined and the first bis(perfluoroalky1)sulphur oxyimines (CF,),S(O)NH, CF,(C,F,)S(O)NH and (C,F,),S(O)NH have been prepared and some of their chemistry in~estigated.~~ The thermal transformations of sulphuryl di-imide, SO,(NH), between 370 and 470 K have given rise to a variety of compounds, including cyclic (NH,NSO,) ; there is evidence that the ring forms via linear oligomers." The similarity between O=SF and R,N=SF (R = perhalogenoalkyl) has been borne out by a study of the reactions of the -N=SF group in sulphur difluoride N-perhalogenoalkylimides which are readily exchanged by R' ,NSiMe,, R1N(SiMe2), or R'ONa to give compounds of general formula R,N=S(NR',)F, R,N=S(NR',), RxN=S=N-R' RxN=S(OR')F and R,N=S(OR') .81 Selenium and Tellurium.-A translation of a Russian book on selenium and the selenides*," and a review of the chemistry of inorganic selenium have appeared recently.The X-ray crystallographic determination of the structure of Se,(HS,O,), has shown that the Se,' + cation is ~quare-planar~~ and Te,(AlCI,) and Te,-(Al2Cl,) have been shown to contain Te4,+ which is like Se42+.84a In both cases the M-M bond distance in the cation is shorter than the M-M single-bond distance indicating a bond order greater than unity.Claims that yellow compounds containing tellurium in the + 1 oxidation state are Te," species have been Selenium and tellurium chains have also been the subject of a number of publications during the past twelve months. Two types of extended-chain crystals have been obtained by quenching pure liquid Se in evacuated Pyrex ~apillaries.~~" The selenopentathionate ion (which contains the S-S-Se-S-S \ / / \ The chemistry of compounds containing the S N-79 D. T. Sauer and J. M. Shreeve Inorg. Chem. 1972,11 238. Y. Ito Nippon Kagaku Kaishi 1972 320. R. Mews and 0. Glemser Znorg. Chem. 1972 11 2521. 8 2 ( a ) D. M. Chizhikov and V. P. Shchastlivyi 'Selenium and the Selenides' Gleichenhaus, New York 1971 ; ( 6 ) J.W. George in 'MTP Internat. Rev. Sci. Inorg. Chem. Ser. One' 1972 2 229 ed. C. C. Addison Butterworths London 1972. 83 I. D. Brown D. B. Crump and R. J. Gillespie inorg. Chem. 1971 10 2349. 84 (a) T. W. Couch D. A. Lokken and J. D. Corbett Inorg. Chern. 1972 11 357; (b) N. J. Bjerrum ibid. p. 2648; ( c ) R. C. Paul C. L. Arora J. K. Puri R. N. Virmani, and K. C. Malhotra J.C.S. Dalton 1972 781. .s5 ( a ) M. C. Coughlin and B. Wunderlich J . Polymer Sci. Part B Polymer Letters 1972, 10 57; (b) K. Boeyum and K. Maroey Acta Chem. Scand. 1971 25 2569; (c) A. Hordvik and K. Julshamn ibid. p. 2507; ( d ) G. Llabres 0. Dideberg and L. Dupont, ibid. 1972 28 2438; ( e ) C. J. Marsden and G. M. Sheldrick J . Mol. Strucrure 1971, 10 419; (f) W.Siebert and A. Ospici Chem. Ber. 1972 105 464 The Typical Elements 263 chain) has been observed for the first time in the transform in (NH,),Se(S,O,),-jH,0.85b The structure of 6a-selenaselenophthen (67) which contains a linear three-selenium-atom sequence built into an aromatic ring system has been 0 Se- Se- Se studied to find out to what extent the Se-Se bonds are shortened by n-b~nding.~" Diphenyl ditelluride PhTeTePh,85d and bis(trifluoromethy1) diselenide F3C-SeSeCF ,85e structures have been determined by X-ray analysis and electron diffraction respectively. An unusual ring compound (PhB),Se (68) has resulted Se-Se / \ Ph-B B-Ph (68) from a rearrangement reaction of the phenylselenadi-iodoborane C,H,SeBI .8 sf Brief notes on the i.r.spectra and thermodynamic functions of Se0286a and Te0,86b have appeared and matrix Raman data for monomeric SeO have been reported for the first time.86c Polymerization of the latter in the matrix produced the dimer which was shown to have the centrosymmetric chair (C,,,) configuration, as well as higher aggregates.86' X-Ray single-crystal analysis of Te205 has shown that the structure is composed of [TeV'0,]n2"- sheets containing octahedral Te between which lie [Te'V0]n2n+ chains running parallel to the b-axis. The terminal oxygens in the TeV' octahedra are also bonded to the Te" forming a three-dimensional system.8 Electron-diffraction studies on the molecular structures of (F,C),Se88" and F3CSeCN88b have been carried out and the crystal structures of six Te" com-plexes e.g.tetrakis(selenourea)tellurium(II) and trans-diselenocyanatobis(tri-methylenethiourea)tellurium(r~),~ have been determined. Differential thermal analysis studies of SeO in dry nitrogen or oxygen atmo-spheres indicate that it decomposes in two stages to form Se205 as an inter-mediate.g0 Complexes of SeO of a 1 1 molar ratio have been prepared with 8 6 8 7 8 8 8 9 90 ( a ) S. Nunziante Cesaro M. Spoliti A. J. Hinchcliffe and J. S. Ogden J . Chem. Phys., 197 1,55,5834; ( b ) M. Spoliti S. Nunziante Cesaro and E. Coffari J . Chem. Therrnodyn., 1972,4 507; (c) G. A. Ozin and A. Vander Voet J . Mol. Structure 1971 10 173. 0. Lindqvist and J. Moret Acta Chem. Scand. 1972 26 829. ( a ) C. J. Marsden and G . M. Sheldrick J . Mol. Structure 1971 10 405; ( 6 ) C.J. Marsden and G. M. Sheldrick ibid. p. 413. See K. Ase 0. Foss and I. Roti Acta Chem. Scand. 1971 25 3808 and references therein. E. E. Sidorova S. N. Kondrat'ev K. N. Mochalov G. 1. Blagoveshchenskaya and K. P. Pribylov Zhur. neorg. Khim. 1972 17 299 264 D. W. A . Sharp M. G. H. Wallbridge and J. H. Holloway AsC1 SbCl, and SbCl in cold SO solutiong1o and with several organic tertiary bases in SO or MeN0,.91b These latter complexes are said to retain the SeO, tetrameric ring but the spectra of the 1 1 adducts with trimethylamine and pyridine prepared by the decomposition of the bis(trimethylsily1) selenate adducts have been assigned on the basis of monomeric molec~les.~'~ Despite several earlier attempts the structure of tellurium tetrachloride has only recently been shown by X-ray methods to be based on the tetrameric unit Te,Cl, with a co-ordination number of six for each Te atom.92" Other struc-tural investigations of interest include the covalent (Q) form of di-iodo(dimethy1)-tellurium which comprises three crystallographically independent Me,TeI, molecules in the asymmetric unit.In each molecule the tellurium has a distorted octahedral environment formed by two trans-Te-I bonds two cis-Te-C bonds, and two weak intermolecular Te - I contacts.92b The product of the reaction of TeBr and cyclohexane which was known to have the formula (TeBrC,H ,,), , has been shown to consist of molecules of Te2Br,C6Hl (69).92c An X-ray n (69) investigation of K,TeI has shown that the crystals are monoclinic rather than triclinic as was reported earlier and that the structure is more distorted than K,TeBr from the cubic K,PtCl structure.92d New spectroscopic data for SeF (Raman of solid liquid and gas and i.r.of gas) and SeOF (Raman of solid liquid and gas) have been reported and dis-cussed with special reference to polymerization in the condensed phases.93P 9 1 ( a ) J . Touzin and M. Jaros Z . Chem. 1971,11,469; ( 6 ) R. C. Paul R. D. Sharma and K. C. Malhotra Indian J . Chem. 1972,10,428; ( c ) R . Kurse and R. Paetzold Z . anorg. Chern. 1972,387 367. 92 ( a ) B. Buss and B. Krebs Inorg. Chem. 1971,10,2795; ( 6 ) L. Y. Y. Chan and F. W. B. Einstein J.C.S. Dalton 1972 316; ( c ) A. C . Hazell Acta Chem. Scand. 1972 26, 1510; (d) S. Syoyama K. Osaki and S .Kusanagi Inorg. Nuclear Chem. Letters 1972, 8 181. 93 ( a ) L. E. Alexander and I. R. Beattie J.C.S. Dalton 1972 1745; ( 6 ) G. A. Ozin and A. Vander Voet J . Mol. Structure 1971 10 397; (c) W. R. McWhinnie and M. G. Patel J.C.S. Dalton 1972 199; ( d ) W. R. McWhinnie and P. Thavornyutikarn ibid., p. 551 The Typical Elements 265 Normal-co-ordinate calculations on TeCl,Br have been carried out in the light of the recent X-ray work on TeCl 9 2 a and it has been concluded that the data can be best interpreted as arising from a mixture of at least the two high-symmetry conformers rather than just the low-symmetry C molecule as was reported last year.93b Far4.r. and Raman studies on diaryltellurium dihalides R,TeX, (Xe = C1 Br or I) have led to the conclusion that the $-bipyramidal structure with axial halogen atoms holds for a considerable variety of groups R.93c For aryltellurium trihalides the data suggest that some association occurs and that dimeric structures involving five-co-ordinate tellurium are most probable for chlorides and iodides.Some of the tribromides may be more associated.93d Mixed tellurium chloride azides Cl,TeN and Cl,Te(N,) have been prepared by the reaction of TeC1 with Me,SiN,. However with SCl and SeC1 reduc-tion occurs. The tellurium dichloride diazide reacted with Ph3P to give (Ph,P NPPh,),TeCl .94 Evaporation of solutions of tellurium halides in Me,NC(O)H and Me,NC(O)Me has given rise to the adducts TeX4,2.5Me,-NC(0)H (X = C1 or Br) TeI4,1.5Me,NC(O)H and TeX,,Me,NC(O)Me (X = C1 Br or I).95 SeF,Cl has been prepared for the first time by first preparing CsSeF from CsF and SeF and then condensing on ClS0,F at 77 K.The mixture is allowed to warm slowly to room temperature before the SeF,Cl is separated by fractional c~ndensation.~~" Physical properties n.m.r.96a and vibrational spectra,96a and thermodynamic properties96b have all been recorded. The reaction Of TeF with Me,SiOH in a sealed tube at room temperature results in the formation of TeF,OH by cleavage of the Si-0 bond rather than the 0-H bond as with alcohols. A parallel reaction occurs with triphenyl~ilanol.~~ Pentafluoro-orthoselenic acid has been synthesized from selenyl fluoride and a large excess of fluorosulphuric acid (SeO,F + 2HOS3F + KHF -+ HOSeF + H2S04 + KS0,F) and vapour pressure melting point boiling point and i.r.and n.m.r. spectra have been reported.98a The pentafluoro-orthoselenates M+SeOF,- (M = Li Na K Rb Cs or NH,) and Hg(OSeF,) have been pre-pared and characterized by n.m.r. and i.r. analysis,98b and F,Se-O-SO,-O-S0,F and F,Se-0-CO-CF have been prepared from the reaction of F,SeOH with SO and CF,COCl re~pectively.~~' New esters (70) of pentafluoro-orthotelluric acid have also been prepared by the route shown.99 The reactions were carried out at ice temperature in tetrachloroethylene (R = H or Me) or F,TeOH + N,CHR -+ F,TeOCH,R + N, (70) (R = H Me or C0,Et) 9 4 N. Wiberg G. Schwenk and K. H. Schmid Chem. Ber. 1972 105 1209. 9 5 9 6 ( a ) C. J. Schack R. D. Wilson and J. F. Hon Inorg. Chem. 1972 11 208; (6) K. 0. 9' G.W. Fraser and J. B. Millar J.C.S. Chem. Comm. 1972 1 1 1 3. M. Perier and G. Vincentini Anais Acad. brasil. Cienc. 1971,43 119. Christe C. J. Schack and E. C. Curtis ibid. p. 583. ( a ) K. Seppelt Angew. Chem. Internat. Edn. 1972,11,630; ( b ) K. Seppelt Chem. Ber., 1972 105 2431; (c) K. Seppelt ibid. p. 3131. 9 9 F. Sladky and H. Kropshofer Inorg. Nuclear Chem. Letters 1972 8 195 266 D. W. A . Sharp M . G. H . Wallbridge and J. H. Holloway methylene chloride (R = C0,Et). The SeV' species SeO,F, FSeO,(OR) [R = Me or Et] SeO,(OMe) and SeO,(OSiMe,) all form 1 1 complexes with the donors 2,2'-bipyridyl pyridine R,N and dioxan and these have been characterized by i.r. spectroscopy. The adducts are thermally labile; L,SeO,(OSiMe,) (L = donor ligand) thermally decomposes to L,(Me,Si),O and SeO but L,SeO,(OMe), and L,SeO,F(OEt) rearrange to give [L-Me]+ [MeOSeO,]- and [L-Et]+-[FSeOJ- respectively."' X-Ray data have shown that BaTeO,,H,O contains discrete TeO,'- ions with a mean Te-0 distance of 185.5 pm indicative of some double-bond character in the bonds."' Raman and i.r.spectra of solid M,TeO (M = K, Rb or Cs) are indicative of the presence of tetrahedral TeO groups and this has been confirmed by X-ray diffraction studies on the solid solutions formed in the K,TeO,-K,SO system.'02u Of the tellurates M2+Te04,- (M = Mg Ca Sr, Ba Cd or Pb) only MgTeO appears to be of a known structure type (cf. NiWO,). The rest are not isostructural with known structures of analogous tungstates, molybdates or uranates.'02' Exposure of crystalline selenates to 6oCo y-rays at 77 K gave the radicals SeO,- SeO,- SeO,- and Sea,,- and their electronic structures have been compared with those of other isoelectronic species.'03 Polonium.-The chemistry and physical properties of polonium have been authoritatively re~iewed.''~ No chemistry of the element has been reported this year but the vapour pressure of PoO in an oxygen atmosphere has been found to vary according to the relationship P/Torr = - 14.27 x 103/(T/K) + 12.57 (T varies between 991 and 1205 K).lo5 2 GroupVII An excellent comprehensive review on the vibrational spectra ofinorganic fluorides has been pub1ished.lo6 The bond dissociation energy of fluorine which was much debated last year,lo7' has been authoritatively discussed both from the experi-mental and theoretical standpoints.107b The most recent experimental results, obtained using a shock tube as a are in close agreement with earlier values using different technique^.'^^' Improved values for the adiabatic electron affinities of Cl, Br, I, and IBr have been obtained by making proper allowance for the influence of the thermal motion of the target gas,lo8' which had been neglected in earlier work.'08b There is now reasonable agreement between l o o R.Kurze and R. Paetzold Z . anorg. Chem. 1972,387 361. I o L B. R. Nielsen R. G. Hazell and S. E. Rasmussen Acta Chem. Scand. 1971 25 3037. l o 2 (a) P. Tarte and F. Leyder Compt. rend. 1971 273 C 852; ( 6 ) A. W. Sleight C. M. Foris and M. S. Licis Inorg. Chem. 1972 11 1157. ' 0 3 K. V. S. Rao and M.C. R. Symons J.C.S. Dalton 1972 147. ' 0 4 K. W. Bagnail in 'MTP Internat. Rev. Sci. Inorg. Chem. Ser. One' 1972 2 187, ed. C. C. Addison Butterworths London 1972. I o 5 R. H. Steinmeyer and C. H. Kershner J. Inorg. Nuclear Chem. 1971,33 2847. ' 0 6 D. J. Reynolds Adv. Fluorine Chem. 1973 6 1. ( a ) D. W. A. Sharp M. G. H. Wallbridge and J. H. Holloway Ann. Reports 1971, 68 A 354; (5) J. Berkowitz and A. C. Wahl Adv. Fluorine Chem. 1973 6 147; (c) J. Blauer and W. Solomon J . Chem. Phys. 1972,57 3587. l o * ( a ) A. P. M. Baede Physica 1972,59 541; ( b ) A. P. M. Baede and J. Los ibid. 1971, 52,422; A. M. C. Moutinho A. P. M. Baede and J. Los ibid. 1970,51,432 The Typical Elements 267 all the recent values obtained for the electron affinities of C1 and I, but values for Br still vary between 2.23 and 2.87 eV.'O*" The U.V.absorption spectrum of bromine vapour between 220 and 290 nm has been measured at 303 K and deviations from the Beer-Lambert law have been interpreted in terms of the formation of double molecules of Br . However the study shows that even saturated bromine vapour contains oiily about 1% of Br molecules.'09" The first spectra of Cl, Br, and I in the 1.84.0 nm region have been rep~rted.'"~ Raman spectra of liquid F and C1 have been shown to be very similar to gas-phase spectra though those for liquid chlorine at 238.6 K and 1 atm pressure are 7-8 cm- ' lower than the corresponding frequencies in the gas.'Og' The refractive indices of,fluorine (and HF) as a function of wavelength have been determined in order to facilitate the analysis of the flow field in a chemically reacting system of fluorine and hydrogen by interferometric methods.' ' A full set of thermodynamic equations for the heat capacity and vapour pressures of liquid and solid iodine have been obtained.' ' ' Fluorine manufacturing processes have been reviewed' and fluorine has been produced by the electrolysis of an anhydrous NH,F-HF electrolyte."2b The F + H reaction is of special theoretical interest because it is one of the simplest examples of an exothermic chemical reaction and since the FH system involves only 11 electrons the computation of a potential energy hypersurface to chemical accuracy may now be within reach of ab initio calculations.It is against this background that the results of the application of the i.r.chemiluminescence technique to obtain the initial vibrational rotational and translational energy distribution in the products of the exothermic reactions F + H and F + D, are of The method has also been applied to measure the distribution of energy amongst the products of the C1+ HI and C1+ DI reactions and prelim-inary results have been obtained for the reactions of Br + HI and C1+ HBr."3b It is clear that much more work in this and related areas will appear soon,especially in view of the recent extension of the molecular-beam method to reactions other than those of alkali-metal atoms.' 13' Molecular-beam methods have also been applied in a detailed study of the reaction dynamics of the H + X (X = Cl, Br, IC1 or IBr) family of reactions.It was ascertained that the dominant force controlling the dynamics is the halogen-halogen repul~ion."~" The H + X (X = C1 or Br)' 14b and H + F2114c l o g (a) W. Y. Wen and R. M. Noyes J . Phys. Chem. 1972,76 1017; (b) C. J. Humphreys and E. Paul jun.,J. Opt. Soc. Amer. 1972,62,432; ( c ) J. C. Barraland 0. Hartmanshenn, Compt. rend. 1972 274 B 981. A. B. Lindenberg Compt. rend. 1971 273 C 1017. (a) N. Watanabe Kagaku To Kogyo (Tokyo) 1972,23,615 ; (6) M. Caron C. Coquet, P. Coste and M. Rey Ger. Offen. 2 108 277/1971. ' I 3 (a) J. C. Polanyi and K. B. Woodall J . Chem. Phys. 1972,57 1574; (b) D. H. Maylotte, J. C. Polanyi and K. B. Woodall ibid. p. 1547; ( c ) J. B. Cross and N . C. Blais ibid., 197 1,55. 3970. ' l a ( a ) J . D. McDonald P.R. Le Breton Y . T. Lee and D. R. Herschbach J . Chem. Phys., 1972 56 769; (6) K. G. Anlauf D. S. Horne R. G. MacDonald J. C. Polanyi and K. B. Woodall ibid. 1972 57 1561; (c) J. C. Polanyi and J. J. Sloan ibid. p. 4988. 1 1 0 W. F. Rumpel G. Yanow and D. F. Penning J . Chem. Phys. 1972,57 3011. ' I 268 D. W. A . Sharp M. G. H . Wallbridge and J. H . Holloway reactions have also been examined by the i.r. chemiluminescence technique. The kinetics of the reaction between H and F have been studied by e.p.r. methods." 5 a and a study of the H,-Cl reaction in nickel flow-reactors has given reaction sequencies for both the gas-phase and surface reactions.' ' 5' Far-ix. spectra have been obtained of the charge-transfer complexes between 1X (X = I Br or C1) and a variety of organic sulphides.This is the first systematic study of such complexes with the sulphur atom as donor.'16' The dipole moments of iodine complexes with Me,SO and other oxygen-containing bases indicated the significance of the dipole moments of the oxygen lone pairs as well as the large contributions from the inductive effect.' 16' Relatively little seems to have been published this year on halogen anions, but e.s.r. observations of C1 -,adsorbed on the zeolites faujasite andmordenite,' ' 7 a and Br - in irradiated single crystals of the clathrate 4-p-hydroxyphenyl-2,2,4-trimethylchroman and 1,2-dibromo-l,l-difluoroethane' '" have been reported. More reviews on the chemistry of halogen and interhalogen cations have appeared.". ' '* The chlorination of aromatic compounds by HOCl has been the subject of many papers; however the most recent paper on the topic 'The last of Chlorinium Ion C1" ' I 9 has dismissed the popular intermediate by means of a thorough kinetic study.It is concluded that it is very improbable that C1+ is significantly involved in any thermal reaction ever studied in solution. As far as HOCl is concerned there are two reactive intermediates formed chlorine monoxide and the protonated species H,O-CI and these two together account for all the reactions. A melting point uersus mole-fraction investigation coupled with n.m.r. and i.r. examination of the I,-S,O,F system has confirmed the existence of I(SO,F) ISO,F and I,SO,F and established the existence of a new species I,(SO,F). In contrast to many other systems no evidence was obtained for The oxidation of bromine with S,O,F in solution in fluorosulphuric acid and in the super-acid system SbF5-3S03-HS0,F has produced the cations Brzf and Br,' together with BrS03F and Br(S0,F)3.'20a More evidence against claims that C1,' or ClF' are produced in SbF, HS0,F-SbF, or HF-SbF solutions has been obtained from an investigation of the reactions of ClF and C1F-Cl with the SbF-3SO3-HSO,F system.E.s.r. spectra of the solu-tions which were previously assigned to CIF' appear to be due to oxygen-containing species,' ,'' as has been suggested before.' ,'' Photoelectron spectra, obtained from the molecules I and Br, have been used to assign the electron 'Is ( a ) S . W. Rabideau H. G. Hecht and W. B. Lewis J . Magn. Resonance 1972 6 384; ( b ) L.S. Bernstein and L. F. Albright Amer. Inst. Chern. Engineers J . 1972 18 141. 'I6 ( a ) M. Yamada H. Saruyama and K. Aida Spectrochim. Acta 1972 28A 439; ( b ) L. Sobczyk and J. Danel J.C.S. Faraday I 1972 68 1544. '" ( a ) J. A. R. Coope C. L. Gardner C. A. McDowell and A. J. Pelman Mol. Phys., 1971,21 1043; (b) L. D. Kispert and J. Pearson J . Phys. Chem. 1972,76 133. R. J. Gillespie and M. J. Morton in 'MTP Internat. Rev. Sci. Inorg. Chem. Ser. One', 1972,3 199 ed. V. Gutmann Butterworths London 1972. ' I 9 C. G. Swain and D. R. Crist J . Amer. Chem. SOC. 1972 94 3195. 1 2 0 ( a ) R. Gillespie and M. J . Morton Inorg. Chem. 1972 11 586; (b) R. J. Gillespie and M. J. Morton ibid. p. 591; ( c ) R. S. Eachus T. P. Sleight and M. C. R. Symons, Nature 1969,222,769; (d) F.G. Herring and R. A. N. McLean Inorg. Chem. 1972,11, 1667 The Typical Elements 269 spectra of the cations 12+ and Br2+.120d The triatomic cation 13+ has been obtained for the first time in a solid compound I +AlC14- and has been charac-terized by n.q.r. methods.' 2'a The 19F n.m.r. spectrum of ClF + has been observed for the first time"lb and the new salt I2C1+SbCl6- has been prepared and shown I + I to contain the / \ cation.121c This is only the second interhalogen cation I c1 to be isolated which contains no fluorine. A crystal-structure determination of the 1 2 adduct formed by BrF and SbF has shown that the crystals contain infinite chains of discrete BrF4+ and Sb,F 1- ions coupled by relatively weak fluorine bridges.lZ2" A number of species containing BrF,' have been obtained by the reaction of BrF with various Lewis acids and tentative assignments of the vibrational spectra have been made.'226 The electrolysis of BrF with platinum electrodes results in the stepwise reduction of BrF,' to bromine.'22C The penta-atomic cation I s + has been characterized by n.q.r.in the solid A new and stable species C1F6+ has been characterized independently by two l a b ~ r a t o r i e s . ' ~ ~ " ~ The IF6+ ion has been studied by 19F n.m.r. in anhydrous HF.123C Avery useful guide to the treatment ofinjuriescaused by HF hasjust appeared.' 24 It has been concluded from 19F n.m.r. data that the normal H-F bond length is 95 & 3 ~ m . I ~ ' The orthorhombic form of HCI has been studied by X-ray and neutron diffraction' 26a and by Raman spectroscopy.' 26b*c No appreciable change to the cubic phase was detected in the crystal structure at the transition point (98 K).'26" The N02F-HF system which is similar to the NOF-HF system contains the adducts N02F,3.5HF N02F,4.0HF N02F,5.25HF and N02F.6.66HF (cf: page 233 ref.149).lZ7 It has been shown that some halogen fluorides can be salted out of solution from anhydrous HF by the presence of high concentrations of NaF.'28" Phase diagrams for the systems HF-MF (M = V Nb Ta or Sb) have been obtained and the stabilities of the complexes formed in the systems discussed. The complex SbF,,SHF is said to be the most stable.'28b Ab initio self-consistent-field calculations of potential-energy curves for the 1 + A1C14- .I 2 a ( a ) D. J. Merryman P. A. Edwards J. D. Corbett and R. E. McCarley J.C.S. Chem. Comm. 1972,779; ( 6 ) M. Brownstein and J. Shamir Canad. J. Chem. 1972,50,3409; ( c ) J. Shamir and M. Lustig Inorg. Nuclear Chem. Letters 1972 8 985. ''' ( a ) M. D. Lind and K. 0. Christe Inorg. Chem. 1972,11,608; ( b ) T. Surles A. Perkins, L. A. Quarterman H. H. Hyman and A. I. Popov J. Inorg. Nuclear Chem. 1972 34, 3561 ; ( c ) H. Meinert and U. Gross 2. Chem. 1972 12 150. I Z J ( a ) F. Q. Roberto Inorg. Nuclear Chem. Letters 1972 8 737; ( 6 ) K. 0. Christe ibid., p. 741 ; ( c ) M. Brownstein and H. Selig Inorg. Chem. 1972 11 658. l Z 4 A. J. Finkel Ado. Fluorine Chem. 1973 7 199. ''* S. P. Gabuda and Yu. V. Gagarinskii Doklady Akad. Nauk S.S.S.R. 1972,202 1065. ( a ) N.Niimura K. Shimaoka H. Motegi and S. Hoshino J. Phys. SOC. Japan 1972, 32 1019; ( b ) R. Heastie Chem. Phys. Letters 1972 15 613; (c) T. S. Sun and A. Anderson Spectroscopy Letters 197 1,4 377. ( a ) M. Brownstein and J. Shamir Inorg. Nuclear Chem. Letters 1971 7 997; ( 6 ) V. K. Ezhov Zhur. neorg. Khim. 1972 17 661. 1 2 ' F. See1 and V. Hartman J. Fluorine Chem. 1972 2 99 270 D. W. A . Sharp M . G. H . Wallbridge and J. H. Holloway ground and first-excited states of HF' have been ~erf0rmed.l~' The first direct experimental evidence for the angular fluoronium ions FH,+ FO,' and FHD+ has been obtained by vibrational spectroscopy and it has been shown that in the presence of liquid HF the ions are strongly solvated in the form (HF),H+.I3' The radiofrequency and microwave transitions of the K = 0 states of (HF),, HFDF and (DF) have been observed by the molecular-beam electric-resonance technique.The dimers have been shown to be non-linear and higher polymers may have cyclic structures since they appear to be n~n-polar.'~' Bond energies in FHF-,13," ClCHC1 BrHBr and IHI'32b and the vibrational frequencies for the three radicals'32b have been calculated. The IHI radical has been identified in the condensate after mixtures of iodine hydrogen and argon had been passed through a glow discharge and then condensed on to a window at 16 K. The i.r. spectrum showed that the radical has a linear symmetric (Dcoh) structure'32c like that of BrHBr. The free energy and enthalpy of the reactions X-(solv) + HCl(so1v) + HClX-(solv) have been determined from calorimetric measurements in the weak dipolar aprotic solvent sulpholane.The data com-bined with values of the heat of solution of HC1 have provided new minimum hydrogen-bond energies (58.2,44.8 and 33.5 kJ mol- ' respectively for C1- Br-, and I - ) for HClX-.'32d Inorganic hypofluorites have been reviewed.' 3 3 The kinetics and mechanism of the reaction C1,O + NOCl- C1 + N0,Cl have been studied spectrophotometrically in solution and the rate has been determined as -d[NOCl]/dt = k[Cl,O][NOCl] with k = 104.'6*0.25 Electron resonance spectra for BrO and I 0 have been obtained.' 3 5 a New potential-energy curve calculations for I 0 have produced a value for the dissociation energy which agrees well with the experi-mental value of 1.9 f 0.2 eV.135b The physical chemistry and mechanisms of many reactions involving C10, have been reviewed in E.s.r.studies have revealed C10 as the reaction product resulting from the electrolytic oxidation of perchlorate salts in ethereal solutions,'36b and BrO has been observed after 6oCo y-irradiation of various crystalline bromates and frozen aqueous glasses.' O 3 Pulse radiolysis of PhBr mol- 1 - 1 134 e( - 7 5 00 f 450)/R T 1 . J. Raftery and W. G. Richards J . Phys. (B) 1972 5 425. 1 3 0 M. Couzi J. C. Cornut and Pham Van Huong J . Chem. Phys. 1972,56,426. 1 3 ' T. R. Dyke B. J. Howard and W. Klemperer J . Chem. Phys. 1972,56 2442. L 3 2 (a) H. P. Dixon H. D. B. Jenkins and T. C. Waddington J . Chem. Phys. 1972 57, 4388; ( b ) D. G. Truhlar P. C. Olson and C.A. Parr ibid. p. 4479; ( c ) P. N. Noble, ibid. 1972 56 2088; ( d ) R. L. Benoit M. Rinfret and R. Domain Inorg. Chem., 1972 1 1 2603. 1 3 ' M. Lustig and J. M. Shreeve Adu. Fluorine Chem. 1973 7 175. 1 3 4 H. Martin J. Robisch H. D. Knauth and K. G. Prusseit Z . phys. Chem. (Frankfurt), 1972 77 227. 1 3 5 (a) J. M. Brown C. R. Byfleet B. J. Howard and D. K. Russell Mol. Phys. 1972, 23,457; ( b ) V. M. Trivedi and V. B. Gohel J . Phys. ( B ) 1972 5 L38. ' 3 6 ( a ) G. Gordon R. G. Kreffer and D. H. Rosenblatt Progr. Inorg. Chem. 1972 15, 201; ( b ) G. E. Glass and R. West Inorg. Chem. 1972 11,2847; ( c ) J. M. Bossy M. W. Leoni and R. E. Buehler Helv. Chim. Acta 1972 55 107 The Typical Elements 27 1 saturated with oxygen has also given rise to BrO, which was detected by its visible spectrum.' 36c Crystal-structure determinations on KIO,,HIO are in good agreement.'37a9 The HIO and 10 groups are pyramidal.Strong 0-1 e e - 0 interactions and electrostatic attractions between K + and 0'- give slabs which themselves are connected by hydrogen bonds. Defects in NaCIO single crystals induced by X-irradiation have been shown by e.s.r. methods to be due to ClO, ClO, and 0,- f0rmati0n.l~~ The BrO radical has been observed in various crystalline bromates and both BrO and possibly BrO,,- have been detected in BaSO, doped with bromate after subjection to 6oCo y-irradiation. ' O3 Vibrational spectra and force constants for ClO,- BrO - and 10,- in aqueous s01ution,'~~~ the i.r. spectra for anhydrous gaseous liquid and solid Cl,07 and the Raman spectrum for liquid C1207' 39b have been obtained.The intermediate formation of 10,- and the subsequent conversion into 10,- have been observed by i.r. methods in a very neat experiment in which KMnO and KI were mixed and pressed into a KI The Raman spectra of anhydrous HF solutions containing ClOF alone or together with SbF, AsF, or BF have provided evidence for ClOF,+ (sym-metry group C,).140 Chlorine oxide trifluoride ClF,O which was first mentioned in the open literature in 1970,'41a has been the subject of a number of Preparations by the direct fluorination of C1,0 NaClO, or ClONO or by subjecting F toa glow dischargein the presence by the photochemical combination of the elements or from halogen oxide fluorides and F, ClF or ClF, or from ClF and O2l4'' have been described.Physical pr~perties,'~'' vibrational s p e ~ t r a ' ~ ' ~ ~ and thermodynamic properties 141d have been discussed in detail. It has been demonstrated that the main reactions of the compound involve fluorination oxygenation or both oxygenation and fluorination of the ~ u b s t r a t e s ' ~ ' ~ and that the compound is amphoteric forming complexes with strong Lewis acids and bases.' 41s For example with alkali-metal fluorides, MF,ClF,O (M = Cs Rb or K) adducts are formed ; with SbF, AsF, and BF,, crystalline 1 1 adducts are produced; and with SiF, the complex SiF4,2C1F,O is given.','/ With PtF, fluorine is liberated to give the new complex C1F20+-PtF -. l4 l e The ClF,O- ion has been fully characterized by vibrational spectro-scopy and has a C, structure analogous to that of ClF or XeOF Reactions 1 3 ' ( a ) G.Kemper A. Vos and H. M. Rietveld Canad. J . Chern. 1972 50 1134; ( 6 ) 1 3 ' 0. Vinther J . Chem. Phys. 1972 57 183. 1 3 ' ( a ) D. J . Gardiner R. B. Girling and R. E. Hester J . Mol. Structure 1972 13 105; ( b ) A. C . Pavia J. Roziere and J. Potier Compt. rend. 1971 273 C 781 ; ( c ) T. Gym-kowski D. G . Lambert and H. s. Kimmel J . Inorg. Nuclear Chern. 1972 34 1841. 140 R. Bougon J. Isabey and P. Plurien Cornpt. rend. 1971 273 C 4!5. 14' ( a ) R. Bougon J. Isabey and P. Plurien Cumpt. rend. 1970 271 C 1366; ( 6 ) D. Pilipovich C. B. Lindahl C. Schack R. D. Wilson and K. 0. Christe Znurg. Chem., 1972 11 2189; ( c ) D. Pilipovich H. H. Rogers and R. D. Wilson ibid. p. 2192; (0 K.0. Christe and E. C. Curtis ibid. p. 2196; ( e ) C. J. Schack C. B. Lindahl D. Pilipo-vich and K. 0. Christe ibid. p. 2201 ; (f) K. 0. Christe C. J. Schack and D. Pilipovich, ibid. 1972 11 2205; ( g ) K. 0. Christe and E. C. Curtis ibid. p. 2209; (h) R. Bougon, Compt. rend. 1972 274 C 698. L. Y . Y. Chan and F. W. B. Einstein ibid. 1971 49 468 272 D. W. A . Sharp M. G. H. Wallbridge and J. H . Holloway of CIOF with PF and ClF have given new complexes which have been formulated as ClOF,+PF,- and ClOF,+ClF,- on the basis of i.r. and Raman ~ p e c t r a . ' ~ ' ~ The complexes ClO,SbF and C102Sb,F,6 are claimed to result from the reaction of SbF with CI0,F,'42" and reaction of C10,F with PtF has given the adduct ClO,F,+PtF,- in which the cation has been characterized by its i.r.The 10,F- radical has been observed in y-irradiated crystals of KIO,F and the possible structures of the ion have been d i s c ~ s s e d . ' ~ ~ Molecular orbital calculations carried out on CIOF 5 c indicate considerable 3d orbital participation in the bonding of the central atom. The enthalpy of formation of Br0,F (AH;1298.15 = 112.1 f 1.1 kJmol-') and other thermo-dynamic properties have been obtained from calorimetric rneasurement~.'~~ Traces of the new species ClO,F have been identified by i.r. in the 131 K fraction of the condensate from the reaction of excess of FNO at 195 K with a mixture of Enthalpies of formation for MIO,F (M = Na K Rb or NH,) have been ~ b t a i n e d . ' ~ ~ " . ~ The i.r. and Raman spectra of the Na' and K+ salts are similar, showing that the shape of the IO,F,- ion is the same in each compound.'46b The shape of the ClO,F,- ion can be derived from a trigonal bipyramid (symmetry C2J with the two fluorine atoms occupying the axial positions while the oxygens and a lone pair are equatorial.'46' Following the identification of ClF by matrix i.r.spectroscopy preliminary evidence for the species Cl,F Cl,F, and CI,F has now been rep~rted.'~' A comprehensive systematic study of the reactions of ClF ClF ClF and C10,F with monofunctional and bifunctional hydroxy-compounds has been made'48" and the primary hydrolysis product of the reaction of ClF with water has been shown to be C10F.'48b The dipole moment of ICl has been deduced from Stark-effect measurements in a microwave study of 13%1 and 137C1.'49 A new preparative method for pure BrF involves the reaction of fluorine with elemental bromine in CC1,F.'" Nitrosyl tetrachloroiodate NOICl, has been prepared from iodine chlorine and NOCl at 233 K and identified at low tempera-tures by Raman spectroscopy.Warming to 248 K resulted in the decomposition C1o2 +PtF6 - and 10 % C1F202 + ptF6-.l4, ( a ) Z. K . Nikitina and V. Ya. Rosolovskii Izvest. Akad. Nauk S.S.S.R. Ser. Khim., 1972 750; (b) K. 0. Christe Inorg. Nuclear Chem. Letters 1972 8 453. 1 4 3 S. Subramanian and M. T. Rogers J. Phys. Chem. 1971 75 3479. L44 G. K. Johnson P. A. G. O'Hare and E. H. Appelman Inorg. Chem. 1972 11 800. 1 4 5 K. 0. Christe Inorg. Nuclear Chem. Letters 1972 8 457. ( a ) A. Finch P. N . Gates and M.A. Jenkinson J.C.S. Dalton 1972,2044; (b) A. Finch, P. N. Gates and M. A. Jenkinson J . Fluorine Chem 1972 2 1 1 1 ; ( c ) K. 0. Christe and E. C. Curtis Inorg. Chem. 1972 11 35. 14' M. R. Clarke W. H. Fletcher G . Mamantov E. J. Vasini and D. G. Vickroy Inorg. Nuclear Chem. Letters 1972 8 61 1 . 1 4 ' (a) K. 0. Christe Inorg. Chem. 1972 11 1220; (b) T. D. Cooper F. N. Dost and C. H. Wang J. Inorg. Nuclear Chem. 1972 34 3564. 1 4 9 E. Herbst and W. Steinmetz J. Chem. Phys. 1972 56 5342. E. Lehmann D. Naumann and M. Schmeisser Z . anorg. Chem. 1972 388 1 The Typical Elements 273 of the salt to NOICl and Cl, and at 323 K NOCl and ICl were produced.'"" The reactions of CsIF and CsIF with excess of (CF,CO),O led to the final products CsI(OCOCF,) and CS,I(OCOCF,)~ respectively.' " The almost square-planar ICl,- ions in the crystal structure of HIC1,,4H2O have been shown to be packed in layers between sheets consisting of a hydrogen-bonded hydrate network.151c New 1 3 adducts of alkali-metal fluorides with IF have been reported and their vibrational spectra obtained.It has been confirmed that the IF6- ion does not have a symmetry higher than C, .l Trifluoromethyliodine(v) tetra-fluoride CF,IF, has been prepared by the oxidation of CF,I with ClF at 195K.'52b Substitutions in IF to give IF,OR (R = Me or Et) have been achieved using Me,SiOR or related compounds in much the same way that has been widely used to prepare aryloxy- and alkoxy-derivatives of covalent fluorides.' 52c The preparation of BrF by the reaction of BrF with fluorine in the presence of MBrF (M = alkali metal) at 380-610 K has been ~ 1 a i m e d .I ~ ~ The Raman spectra of IF in liquid and gaseous anhydrous HF have been and a new study of the vibrational spectra of gaseous IF has confirmed that the molecule undergoes minor dynamic distortions from D, symmetry.' 5 4 Reactions of bromine(1) fluorosulphate with gold and platinum have been described.' 5 5 Iodine(II1) perchlorate I(OCIO,) has been prepared by the low-temperature reaction of iodine with excess ClOClO and Cs+I(0C1O3),- has been synthesized from CsI and ClOClO .156 The chemistry of astatine has been reviewed.'57u Oxidation of astatide and astatine by Cr,O,,- in dilute aqueous solutions results in the production of positively charged ions of astatine.' 5 7 b 3 GroupVIII New reviews stressing the most recent advances in noble-gas chemistry have been published,' and the preparation and physical and chemical properties of KrF have been described.' 58c In the latter paper much preliminary Russian work is mentioned which has not appeared in the open literature.1 5 1 ( a ) J. P. Huvenne and P. Legrand Compt. rend. 1972,274 C 2073; (b) D. Naumann, M. Schmeisser and R. Scheele J. Fluorine Chem. 1972 1 321 ; (c) R. J. Bateman and L. R. Bateman J . Amer. Chem. Sac. 1972 94 1 1 30. ( a ) K. 0. Christe Inorg. Chem. 1972 11 1215; (6) 0. R. Chambers G. Oates and J. M. Winfield J.C.S. Chem. Comm. 1972 839; ( c ) G. Oates and J. M. Winfield, Inorg. Nuclear Chem. Letters 1972 8 1093. 1 5 3 C. E. Fogle and R. T. Rewick U.S.P.3615206/1971. s 4 H. H. Eysel and K. Seppelt J . Chem. Phys. 1972,56 508 1 . 1 5 6 K. 0. Christe and C. J. Schack Inorg. Chem. 1972,11 1682. Is' ( a ) E. H. Appelman in 'MTP Internat. Rev. Sci. Inorg. Chem. Ser. One' 1972 3, 181 ed. V. Gutmann Butterworths London 1972; (6) D. K. Tung I. Dudova and V. Khalkin Joint Inst. Nuclear Invest. Rep. 1971 JINR-P12-5644 (Nuclear Sci. Abs., 1971 25 26209). l S 8 ( a ) F. Sladky in 'MTP Internat. Rev. Sci. Inorg. Chem. Ser. One' 1972 ed. V. Gutmann Butterworths London 1972; ( b ) F. Sladky Allg. prakt. Chem. 1971 22, 213; (c) V. N. Prusakov and V. B. Sokolov At. Energ. 1971 31 259. W. M. Johnson R. Dev and G. H. Cady Inorg. Chem. 1972 11 2260 274 D. W. A . Sharp M . G. H . Wallbridge and J. H. Holloway All the known stable noble-gas compounds contain the noble gas bound either to fluorine or oxygen.However since the discovery of the noble gases the notion that xenon-boron compounds might exist has always seemed attractive' 59a and it has now been shown that O,BF reacts with xenon at 173 K to give a white solid which decomposes at 243 K. Raman and i.r. evidence has shown that this F / \ solid has the structure F-Xe-B .159b F Theoretical calculations suggest that both the related hypothetical molecule Xe-BF and XeB+ salts are unlikely but that zwitterions such as +XeBloH9,-might be possible.' 59c Ab initio calculations on linear symmetric KrF have confirmed Coulson's earlier proposal that the Kr-F bond is ionic in nature near the equilibrium separation and becomes covalent at larger separations.16' A brief report on studies of the KrF,-BrF system mentions that if SbF is added KrF2,2SbF, may be isolated from the mixture but no new compounds can be obtained.161a It has been shown that KrF2,2SbFs has a stretching wavenumber of v(Kr-F+) = 626 cm- ' and may be formulated KrF+Sb,F -.161b*c The oxidizing properties of KrF,' l a and KrF+ ' ,' b* ' have also been discussed and it has been shown that KrF+ will oxidize XeOF to XeOF,+.161' The ideal-gas heat capacities at constant pressure free-energy functions and entropies for XeF, XeF, XeF, XeOF, XeO,F, and XeOF at 1OO-lOOO K have been obtained from spectroscopic data.',, Fluorination of organic species by XeF has been discussed with reference to radical-cation intermediate^'^^" and the mechanisms inv01ved.l~~~ The results of many studies on xenon difluoride complexes have appeared.' 64a-c These include the new species XeF ,XeOF,; XeF ,XeF ,AsF ; XeF ,2XeF6 ,2AsF5 ;' 64a [XeF+],[MF6]2- (M = Ti Zr or Sn).164b XeF2,2BrF, and XeF2,9MFs (M = I s 9 ( a ) J.H. Holloway 'Noble Gas Chemistry' Methuen London 1968 p. 49; ( b ) C. T. Goetschel and K. R. Loos J. Amer. Chem. SOC. 1972,94 3018; (c) J. F. Liebman and L. C. Allen Inorg. Chem. 1972 11 1143. (a) V. N. Prusakov and V. B. Sokolov 2hur.fiz. Khim. 1971,452950; (b) N. Bartlett, D. Gibler D. McKee R. Mews and M. Wechsberg Abstracts of The Sixth Inter-national Symposium on Fluorine Chemistry Durham July 1971 paper C24; (c) D. E. McKee C. J. Adams A. Zalkin and N. Bartlett J.C.S. Chem. Comm.1973,26. 1 6 2 S. A. Kudchadker and A. P. Kudchadker Proc. Indian Acad. Sci. Sect. A 1971 73, 261. 1 6 3 ( a ) J. Burdon I. W. Parsons and J. C. Tatlow Tetrahedron 1972,28,43; ( 6 ) R. Filler, H. H. Hyman and M. J. Shaw J. Org. Chem. 1971,36,2917. 1 6 4 ( a ) N. Bartlett and M. Wechsberg 2. anorg. Chem. 1971 385 5 ; (b) V. N. Legasov, V. N. Prusakhov and B. B. Tchaivanov Report of I. V. Khurtchatov Institute for Atomic Energy IAE-2185 Moscow 1972; (c) B. B. Tchaivanov V. A. Legasov V. N. Prusakov and V. B. Sokholov ibid. IAE-2186 Moscow 1972. ''' P. S. Bagus B. Liu and H. F. Schaefer tert. J. Amer. Chem. Soc. 1972,94,6635 The Typical Elements 275 Br or I).',,' Infrared spectra of 2XeF,,RuF and XeF,,RuF and i.r.165b and Raman'65' data of 2XeF2,SbF,;XeF,,SbF,;2XeF,,3SbF ; and XeF2,2SbF have been published.Reactions of CrF with xenon and XeF have been studied and a non-volatile solid XeCr,F,, has been obtained as well as XeF,.',," Reactions of xenon fluorides with UF and UF have been reported.'66b The new species FXeOPOF and Xe(OPOF,) have been obtained in high yield by the reaction of XeF with P203F4 at 295 K in CC1,F.'67 The structure of xenon(u) fluoride fluorosulphate has established the existence of discrete FXeOS0,F molecules. The F-Xe-0 angle is 177.4(3)" and the Xe-0 bond length is 215.5(8) pm.'68 The recently prepared pentafluoro-orthoselenic acidg8" has been shown to react with XeF to give FXeOSeF and Xe(OSeF,)2.'69 XeF has been used to oxidize neptunium-(v) and -@I) to neptunium(vI1) in alkaline solution.70 The use of XeF to ~ynthesize'~' Xe2FI1+AUF6- is perhaps one of the most significant developments in noble-gas chemistry of late. Although several laboratories have recognized the potential of noble-gas fluorides as powerful fluorinating agents this is one of the first successes. New ground has also been opened up by theoretical and spectroscopic studies on XeF,. The suggestion that, in the vapour XeF is a mixture of three molecular isomers differing in electronic state and nuclear g e ~ m e t r y ' ~ ~ " seems to be borne out by detailed ir. Raman and U.V. spectroscopic investigation^.'^^^ The reaction of UF with XeF has pro-duced the complex XeF,,UF ,' 66b and X-ray investigations suggest that the uF molecules are inserted into a tetrameric XeF lattice.'73 Earlier reports that F,Xe(OSO,F) and F,Xe(OSO,F) had been prepared have been shown to be in~orrect"~ so that at present only three fluorosulphates, Xe(OSO,F) FXeOSO,F and F,XeOSO,F are known.Fluoride glasses containing Xev' have been described.' 7 5 Xenon dioxide tetrafluoride XeO,F has been prepared by the reaction of XeO,F with XeF in XeOF solvent.'76" Raman and i.r. spectra of the matrix-isolated molecule have shown that it has D, symmetry.' 766 The new complexes ' 6 5 ( a ) V. N. Prusakov V. B. Sokolov and B. B. Chaivanov Zhur. priklad. Spekrroskopii, 1972,17 114; ( b ) B. B. Chaivanov 2hur.priklad. Khim. 1972,46,23; (c) G. S. Baronov, N. P. Egorov A. N. Sopikov and B. B. Chaivanov Zhur. f i z . Khim. 1972,46 18. 166 ( a ) J. Slivnik and B. Zemva 2. anorg. Chem.1971 385 137; (6) M. Bohinc and B. Frlec J . Inorg. Nuclear Chem. 1972 34 2942. 1 6 7 M. Eisenberg and D. D. Desmarteau Inorg. Chem. 1972 11 1901 1 6 * N. Bartlett M. Wechsberg G. R. Jones and R. D. Burbank Inorg. Chem. 1972 11, 1124. K. Seppelt Angew. Chem. Internat. Edn. 1972 11 723. K. Leary and N. Bartlett J.C.S. Chem. Comm. 1972,903. and H. Kim ibid. p. 5042. 2938. D. D. Desmarteau and M. Eisenberg Inorg. Chem. 1972,11 2641. "' E. F. Rieblin P. E. Blaszyk and D. W. Smith U.S.P. 3 650 779/1972. ( a ) J. L. Huston J . Amer. Chem. SOC. 1971 93 5255; (6) H. H. Claassen and J. L. Huston J . Chem. Phys. 1971,55 1505. 170 V. D. Klimov V. N. Prusakov and V. B. Sokolov Radiokhimzya 1971 13 725. 1 7 ' L 7 2 (a) G. L. Goodman J . Chem. Phys. 1972,56,5038; ( b ) H.H. Claassen G. L. Goodman, 1 7 3 B. Frlec M. Bohinc P. Charpin and M. Drifford J . Inorg. Nuclear Chem. 1972 34 276 D. W. A . Sharp M . G. H. Wallbridge and J. H. Holloway XeO,F+Sb,F and XeOF3+Sb,F 1- have been synthesized from XeO,F and XeOF, respectively and the "F n.m.r. and Raman spectra of the XeOF,+ and XeO,F+ ions have been interpreted. 1 7 7 The vibrational spectra and force field of XeO have been reported,178a and rules for the estimation of the frequency ratio ~ 1 / ~ 3 of the symmetric and anti-symmetric stretching vibrations of tetrahedral transition-metal 0x0-anions have been extended to cover 0x0-anions of the main-group elements and in particular ~ O X ~ O . ' ~ ~ ' It has been shown that gaseous radon can be oxidized to a solid by oxidants such as ClF ClF ClF their bromine analogues or IF7.The radon compound is probably RnF2.17'" The work has been extended to show that Rn also reacts spontaneously with solid complexes such as ClF,SbF and BrF,Sb,F to yield non-volatile ions and compounds and the possibilities of applying this to the removal of Rn from air in uranium mines has been discussed.179b '" R. J. Gillespie B. Landa and G. J. Schrobilgen J.C.S. Chem. Comm. 1972 607. ''* (a) R. S. McDowell and L. B. Asprey J . Chem. Phys. 1972,57 3062; (6) E. J. Baran, Z. Naturforsch 1972 27b IOOO. (a) L. Stein U.S.P. 3660300/1972; (b) L. Stein Science 1972 175 1463

ISSN:0069-3022    

DOI:10.1039/GR9726900175

出版商:RSC    

年代:1972

数据来源: RSC

摘要:

9 The Transition Elements By W. E. SMITH Department of Pure and Applied Chemistry, The University of Strathclyde Glasgow and J. M. WINFIELD Department of Chemistry The University of Glasgow 1 Introduction The scope and format of this report are similar to previous years and papers dealing with organometallic compounds and kinetics and mechanisms are largely excluded. Coverage is not comprehensive and for this the reader is directed to the appropriate Specialist Periodical Report.* Topics that have been reviewed this year include the magnetic properties of polynuclear compounds,' the use of magnetic resonance techniques for studying electronic structures,2 ligand field spectra and bonding in solid^,^ spin-forbidden electronic bands,4 transition-metal cations in synthetic zeolites,' and photo-chemistry of transition-metal compounds in the solid state and in solution.6 Nomenclature.-Metals are denoted by M cations by A anions by X or Y, organic radicals by R and ligands by L using Latin numerical prefixes to indicate denticity e.g.biL for a neutral bidentate ligand. When possible the first co-ordination sphere is indicated by square brackets and the structures of poly-nuclear compounds are denoted following current usage e.g. anhydrous Mo" chloride is [(Mo6Cl,)C1,C14,,] . Commonly used solvents and ligands are abbreviated as follows dimethyl sulphoxide (DMSO) tetrahydrofuran (THF) dimethylformamide (DMF), ethylenediamine (en) pyridine (py) 2,2'-bipyridyl (bipy) terpyridyl (terpy), ' J. S. Griffith Structure and Bonding 1972 10 87; A.P. Ginsberg Inorg. Chim. Acta Rev. 1971 5 45. D. R. Eaton and K. Zaw Co-ordination Chem. Rev. 1971,7 197. D. Reinen Angew. Chem. Inrernar. Edn. 1971 10 901. L. L. Lohr jun. Co-ordination Chem. Rev. 1972,8 241. I. D. Mikheikin G. M. Zhidomirov and V. B. Kazanskii Russ. Chem. Rev 1972, 41 468. E. L. Simmons and W. W. Wendlandt Co-ordination Chem. Rev. 1971 7 11; W. L. Waltz and R. G. Sutherland Chem. SOC. Rev. 1972 1 241. * 'Inorganic Chemistry of the Transition Elements' ed. B. F. G. Johnson (Specialist Periodical Reports) The Chemical Society London Vol. 1 1972 Vol. 2 1973. 27 278 W. E. Smith and J. M . WinJield 1,lO-phenanthroline (phen) 8-quinolinolate (oxine) 1,2-bis(diphenylphosphino)-ethane (diphos) o-phenylenebis(dimethy1arsine) (diars) acetylacetonate (acac), acetate (OAc) oxalate (ox) and ethylenediaminetetra-acetate (edta).2 The Rare Earths Scandium.-Recent work reported on t h s element again illustrates its similarity to 3d elements and to the lanthanides. The preparation of Sc[N(SiMe,),] from ScCI and LiN(SiMe,) has been described.' The compound forms part of the series M[N(SiMe,),] (M = Sc-Cr and Fe; see also lanthanides) containing trigonally co-ordinated M but from its i.r. spectrum Sc-N n-bonding appears not to be important. X-Ray work has shown that Sc is approximately dodecahed-rally co-ordinated in Sc,(ox) ,6H,O by six carboxylate and two water 0 atoms. The structure is similar to that found for other aquo-oxalato-complexes with each ox group forming two chelate rings (Sc-0 = 218-226pm).8 The com-pounds A,Sc(NO,) (A = K Rb or Cs) are formulated as nitrato-scandates rather than double salts from their i.r.spectra. They are stable in solution only in the presence of concentrated HNO .' Adduct formation between Sc(biX), (biX = thenoyltrifluoroacetonate) and tributyl phosphate (L) has been studied in various solvents. Unlike related systems there was no evidence for adducts other than Sc(biX),L." A procedure for obtaining anhydrous ScX (X = C1 or Br) from aqueous solution has been described" in which hydrolysis of Sc"' is prevented during the preparation by the formation of ScX,,-. The procedure is similar to that used previously to prepare anhydrous LnX (X = Cl-I inclusive), but attempts to prepare ScI were unsuccessful possibly because the formation of SCI,~ - is unfavourable for steric reasons.Yttrium and the Lanthanides.-The behaviour of high-temperature (1 273-1473K) molecular beams of LnF in inhomogeneous electric fields has been examined to obtain information on the vapour-phase structures of these com-pounds. Significant distortions from D, symmetry either of a pyramidal or of an in-plane C, type are indicated for La Gd Lu Sc and Y trifluorides whereas those of Pr Nd Tb Dy and Ho appear to have D, symmetry. Small distortions are indicated where Ln = Ce Er and Tm and are probably absent where Ln = Sm Eu and Yb. It is noteworthy that the significant distortions correspond to fo f' or f " configurations. This study conflicts with some of the structural conclusions drawn previously from the vibrational spectra of matrix-isolated LnF, but the spectrum of PrF has been re-interpreted in D, symmetry.14 The co-ordination chemistry of Sc has been reviewed.', ' E.C. Alyea D. C. Bradley and R. G. Copperthwaite J.C.S. Dalton 1972 1580. * E. Hansson Acfa Chem. Scand. 1972 26 1337. L. N. Komissarova G. Ya. Pushkina and V. I. Spitsyn Russ. J . Inorg. Chem. 1971, 16 1262. l o K. Akiba T. Ishikawa and N. Suzuki J . Inorg. Nuclear Chem. 1971 33 4161. ' * R. W. Stotz and G. A. Melson Inorg. Chem. 1972 11 1720. l 2 G. A. Melson and R. W. Stotz Co-ordination Chem. Rev. 1971,7 133. l 3 E. W. Kaiser W. E. Falconer and W. Klemperer J . Chem. Phys. 1972 56 5392. l 4 M. Lesiecki J. W. Nibler and C. W. DeKock J . Chem. Phys. 1972.57 1352 The Transition Elements 279 Co-ordination numbers greater than six are characteristic of lanthanide compounds in condensed phases but one of the most notable advances this year is the characterization of volatile monomeric Ln[N(SiMe,),] (Ln = La Pr Sm, Eu Gd or Lu) compound^.'^ The Eu"' compound appears to have a structure similar to the Fe"' analogue (see also Scandium) and the compounds thus contain three-co-ordinated Ln"'.The ability of bulky ligands to produce low co-ordina-tion numbers in Ln"' chemistry is illustrated also by [Li(THF),] [LuAr,] (Ar = 2,6-dimethylphenyl) which X-ray work has shown to contain an approximately tetrahedrally co-ordinated Lu atom.' A suggestion that cubic stereochemistry may be as common for LnL groups as it is for the actinides comes from X-ray work on the [La(py0),l3' cation.17 The polyhedron approximates to D symmetry with a large deviation from a square antiprism towards a cube.Bidentate ligands figure largely in this year's work either in new complexes designed to produce high co-ordination numbers, or in physical studies on known complexes. The ligand characteristics of 1,s-naphthyridine (1) towards 3d metals are similar to NO - and high co-ordination numbers can be obtained (see previous reports). Its behaviour to Ln"' has been examined and typical of the products formed are Ln(biL),(NO,) (Ln = La-Nd), Ln(biL),(NO,) Ln = (Y Sm-Yb) [Ln(biL),](ClO,) (Ln = La-Pr) and [Ln(biL),](ClO,) (Ln = Nd-Eu). Co-ordination numbers of 12 or 10 are suggested from spectral and conductance work. Structures for the complexes of Ln"' with the nicotinate anion (2) had previously been formulated assuming the presence of terdentate ligands but X-ray work has shown that they are [(H,O),(biX)Ln(biX),Ln(biX)(H,O),] each Ln having a highly distorted antiprismatic environment with bidentate (2 x 0) nicotinate ligands.While the Gd compound has a normal magnetic moment those of the Pr"' and Nd"' analogues are low." Often a small change in the ligand can produce a change in molecular geometry which may be reflected in the elec-tronic spectrum. Eu"' complexes are particularly favourable for such work (cf: previous reports) and a fluorescence spectral study of antiprismatic [Eu(biX),] -anions indicates that when biX = di-p-bromodibenzoylmethide the anion's structure is (3) compared with the previously determined structure (4) where I s D.C. Bradley J. S . Ghotra and F. A. Hart J.C.S.Chem. Comm. 1972 349. l 6 S . A. Cotton F. A. Hart M. B. Hursthouse and A. J. Welch J.C.S. Chem. Comm., 1972 1225. A. R. Al-Karaghouli and J. S. Wood J.C.S. Chem. Comm. 1972 516. R. J. Foster and D. G. Hendricker Znorg. Chim. Acra 1972 6 371; R. J. Foster, R. L. Bodner and D. G. Hendricker J . Inorg. Nuclear Chem. 1972 34 3795. l 9 J. W. Moore M. D. Glick and W. A. Baker jun. J. Amer. Chem. SOC. 1972,94 1858 280 W. E. Smith and J. M . Winfield biX = dibenzoylmethide. An increase in charge density near Eu"' is suggested in the p-bromo-complex.20 (3) (4) The literature on lanthanide n.m.r. shift reagents appears to be increasing exponentially and several surveys of the use of Ln"' P-diketonate compounds, particularly the ligands 2,2,6,6-tetramethylheptane-3,5-dione (dpm) and 1,1,1,2,2,3,3-heptafluoro-7,7-dimethyloctane-4,~dione (fod) have appeared.2 Attention has been drawn to the persistence of dimeric [Ln(biX),] species in solution the possibility of forming 1 1 or 1 2 shift reagent substrate complexes, and the importance in some cases of contact contributions to the observed shifts, as opposed to dipolar (pseudo-contact) contributions.The X-ray crystal struc-tures of two widely used reagents Ho(dpm),(4Mepy) and Eu(dpm),(py) have been determined.,' In both cases the LnO,N polyhedron is best described as a square antiprism (5). This may be compared with the structure of monomeric Er(dpm) in which Er has trigonal prismatic ~o-ordination.~~ 2o J.J. Degnan C. R. Hurt and N. Filipescu J.C.S. Dalton 1972 1158. 2 1 W. Dew. Horrocks jun. and J. P. Sipe tert. J . Amer. Chem. SOC. 1971 93 6800; J. K. M. Sanders S. W. Hanson and D. H. Williams ibid. 1972 94 5325; B. F. G. Johnson J. Lewis P. McArdle and J. R. Norton J.C.S. Chem. Comm. 1972 535. 2 2 W. Dew. Horrocks jun. J. P. Sipe tert. and J. R. Luber J . Amer. Chem. SOC. 1971, 93 5258; R. E. Cramer and K. Seff Acta Cryst. 1972 B28 3281. 23 J. P. R. de Villiers and J. C. A. Boeyens Acta Cryst. 1971 B27 2335 The Transition Elements 28 1 Single-crystal magnetic anisotropy measurements on [Ln(dpm),(4-Mepy),] (Ln = Pr-Tm) indicate that the susceptibility tensors are highly anisotropic and non-axial. Dipolar n.m.r. shifts calculated using the data agree satisfactorily with those obtained in solution.24 Exchange between 'free' substrate and that bound to Ln(biX) is normally fast on the n.m.r.time scale and separate reson-ances are not observed. An exception to this is the Eu('H,-fod) ,DMSO system in which separated DMSO signals were observed at 193 K and a 1 2 complex is indicated.25 2 1 Complex formation between optically active alcohols and Eu(fod) is indicated also from a c.d. study.26 While shift reagents may be used routinely for 'spreading out' n.m.r. spectra, more detailed work for example determining substrate binding enthalpies or conformations must be undertaken with caution. Commonly made assumptions of 1 1 complex formation and magnetic axiality may not be justified. A general approach using both shift and broadening effects to the use of Ln"' compounds in structural studies has been given2' Mossbauer spectroscopy has proved to be a useful technique for determining the oxidation states of Eu compounds.Thus the phases Eu,C3 EuC, and EuN,C, obtained from Eu and HCN or (CN) at high temperatures have been shown to be band systems while EuN is ionic and contains Eu3+. Reactions in liquid NH between Eu and HCN C,H,,or NH,SCN give Eu" and Eu"' cyanides Eu"' acetylide and Eu"' thiocyanate respectively. It has been suggested also that polymeric and monomeric Eu"' chelates may be differentiated by means of their Mossbauer spectra.28 The previously observed ferromagnetic properties of EuO EuS EuSe and GdN at low temperatures have been interpreted according to indirect exchange betweenfelectrons of different cations via their outer closed shells.This mechan-ism is expected to compete with superexchange via anions which would favour antiferromagnetic beha~iour.~' Electric deflection molecular beam studies' on LnF (Ln = Sm Eu or Yb) show that they are strongly polar molecules in the gas phase and therefore bent structures are indicated. A similar conclusion is drawn from the i.r. spectra of matrix-isolated LnX (X = F or Cl)30 (see also last year's report) and ClLnCl bond angles calculated from isotope frequency shifts are 130 O (Sm) 130 O (Eu) and 140 O (Yb). Complexation energies derived for the formation of Ln(NH3)62 '(8) from Ln2'(g) and NH,(g) are - 1250 and - 1352 kJ mol-' for Ed' and Yb" respec-tively.,' These values are comparable with complexation energies of Group I1 2 4 W.Dew. Horrocks jun. and J. P. Sipe tert. Science 1972 177 994. " D . F. Evans and M. Wyatt J.C.S. Chem. Comm. 1972 312. 2 6 N. H. Andersen B. J. Bottino and S. E. Smith J.C.S. Chem. Comm. 1972 1193. 27 B. Bleaney C. M. Dobson B. A. Levine R. B. Martin R. J. P. Williams and A. V. Xavier J.C.S. Chem. Comm. 1972 791. '* I. Colquhoun N. N. Greenwood I. J. McColm and G. E. Turner J.C.S. Dalton, 1972 1337; J. I. Mackey and N. N. Greenwood J . Inorg. Nuclear Chem. 1972 34, 1529. 2 9 E. Lombardi G. Tarantini R. Block R. Roel G. Ter Maten L. Jansen and R. Ritter, Chem. Phys. Letters 1972 12 534. 3 0 C. W. DeKock R. D. Wesley and D. D . Radtke High Temp. Sci. 1972,4,41. 3 1 R. H. Frisbee and N.M. Senozan J . Chem. Phys. 1972,57 1248 282 W. E. Smith and J. M . Winjeld cations of similar size. Bands in the spectra of transient species observed in the pulse radiolysis of Ln"' solutions have been assigned to transitions between the 4f" and 4P-l 5d levels of Ln2+. The reactions of Ln" with OH- O, N,O etc. indicate that the order of reactivity is Sm" > Yb" > Eu" which correlates with their electrode potential^.^^ 3 The Actinides The first hydrated complexes of UI'I U2(S04)3 ,5H20 (or 2H,O) and M,SO,,U,(SO,)3,xH,O (M = Na K Rb Cs NH, or N2H5; x unknown) have been prepared. A further series of hydrated chlorides divides into two sets : the red set MUCl,,SH,O (M = NH,,K or Rb) have more covalently bound chlorides compared with the green set MUCI,,xH,O (M = NH or Rb) which are ionic.The red set only have a U-Cl stretch in the i.r. spectra. In general, oxygen donor ligands do not give stable complexes of UIII but the compounds U(ph),Cl and U(dmaz),(Ph,B) have now been isolated (ph = phenazone, dmaz = dimethylphena~one).~~ Adducts of type UX,,RCN (X = C1 or Br; R = Me Et Pr" Pri Bn" or Ph) appear to be eight-co-ordinate from spectral and magnetic data. The complexes are weak and easily broken down thermally.34 M11U,VF,2 salts (M = Co Ni or Cu) also appear to be eight-co-ordinate from spectral and magnetic data.35 New preparations of U0,Cl and UOC1236 and the new compound UOF are reported.37 The structure of the complexes UO,(MeCS,) ,Ph3P0 shows that the uranium is seven-co-ordinate with a pentagonal-bipyramidal geometry,' and neutron diffraction data on [U0,H20{CO(NH2),),] (NO,) for which the structure has been uncertain, demonstrates that it has a similar geometry.39 The U02,+ group is linear and the plane has four urea oxygen groups and one water co-ordinating the uranium.The structure is connected by hydrogen bonds through the nitrates. of U(BH,) shows that the structure is polymeric with six BH groups per uranium. There are four bridging groups and two (cis) terminal groups. A neutron diffraction study shows that the four bridging groups are bonded through two U-H-B bonds and the cis terminal groups by three U-H-B bonds.40b The spectrum of Uv has been assigned using an intermediate coupling calculation for an f ' system in a tetragonal field.,' The An X-ray diffraction 32 M.Faraggi and Y. Tendler J . Chem. Phys. 1972 56 3287. 3 3 R. Barnard J. I. Bullock B. J. Gellatly and L. F. Larkworthy J.C.S. Dalton 1972, 3 4 P. Gans and J. Marriage J.C.S. Dalton 1972 46. 3s F. Montoloy P. Plurien and M. Capestan J. Inorg. Nuclear Chem. 1972.34 125. 3 6 S. S. Eliseev I . A. Glukhov and E. E. Vozhdaeva Russ. J . Inorg. Chem. 1972,17,627. 37 P. W. Wilson J.C.S. Chem. Comm. 1972 1241. G. Bombieri U. Croatto E. Forsellini B. Zarli and R. Graziani J.C.S.Ddton 1972, 560. 964 1932 1933, 3 9 N. K. Dalley M. H. Mueller and S. H. Simonsen Inorg. Chem. 1972 11 1840. 40 ( a ) E. R. Bernstein T. A. Keiderling S. J. Lippard and J. J. Mayerle J. Amer. Chem. SOC. 1972,94,2552; (b) E. R. Bernstein W. C. Hamilton T. A. Keiderling S. LaPlaca, S.J. Lippard and J. J. Mayerle Inorg. Chem. 1972 11 3009. 4 1 J. Selbin C. J. Ballhausen and D. G. Durrett Inorg. Chem. 1972 11 510 The Transition Elements 283 choice of coupling scheme to interpret the spectra of uranyl complexes has been considered and the Russell-Saunders scheme found to be superior to the inter-mediate coupling case.42 The new complexes (Et,N),M(NCS)* (M = Th Pa Np or Pu) have the metal at the centre of an almost perfect cube.43 An improved method of preparing trihalides of U Np and Pu by reduction of the tetrahalide with zinc metal at 900K and the preparation of the new oxyhalides NpOCl NpOBr and NpOI are The complex sulphates M2Np02(S04),,2H20(M = K or Cs) and [Co(NH,),] [NpO,(SO,),] xH20 have been prepared (x unknown)."' The di-positive oxidation state of the heavier actinides has become much better characterized this year.New compounds reported are : Am Cm Bk Cf Es Fm Compound AmI - BkH CfBr SmC12.Es2+ SmC12.Fm2+ Reference 46 - 47 48 49 50 Each of these is a first report of that particular oxidation state. The di-positive Es and Fm species are ions doped into SmCl . They were prepared by reduction with Mg of solutions of SmCl and EsCl or FmCl in aqueous ethanol. The rather insoluble SmCl crystallizes out. CfO, the second example of a Cf'" compo~nd,~' and Pull' formate the second example of an actinide(II1) f ~ r r n a t e ~ ~ have been reported. The high temperature form of curium metal has an oxidation state of +3 not + 4 as suggested previo~sly.'~ The crystal structure of Am2(SO,),,8H,O shows that the metal is co-ordinated to four oxygens of the SO, - group and four oxygens from water molecule^.'^ The unit cell dimensions of the actinides show changes which obey the 'tetrad' rule" as do the stability of mono- di- and tri-SCN derivatives of Amii1 CrnI" Bk"' Cf"' and Es~I'.'~ It 4 2 G.Gorller-Walrand and L. G. Vanquickenborne J. Chem. Phys. 1972,57 1436. 43 2. M. S. A1 Kauaz K. W. Bagnall D. Brown and B. Whittaker J.C.S.Dalton 1972, ** D. Brown and J. Edwards J.C.S. Dalton 1972 1757. " M. P. Mefodeva N. N. Knot L. N. Bugahava and A. D. Gelman Russ. J. Inorg. 46 R. D. Baybarz L. B. Asprey C. E. Strouse and E. Fukushima J. Inorg. Nuclear *' J. A. Fahey J. R. Peterson and R. D. Baybarz Inorg. Nuclear Chem. Letters 1972, 2273. Chem. 1972.17.736. Chem. 1972 34 3427. 8 101. J. R. Peterson and R. D. Baybarz Inorg. Nuclear Chem. Letters 1972 8 423. *' N. B. Mikheev V. I. Spitsyn A. N. Kamenskaya N. A. Rosenkevitch I. A. Rumer, and L. N. Auerman Inorg. Nuclear Chem. Letters 1972,8 869. " N. B. Mikheev V. I. Spitsyn A. N. Kamenskaya B. A. Gvodev V. A. Druin I. A. Rumer R. A. Dyachkova N. A. Rozenkevitch and L. N. Auerman Inorg. Nuclear Chem. Letters 1972 8 929. " R. D. Baybarz R. G. Haire and J. A. Fahey J. Inorg. Nuclear Chem. 1972,34,557. " L. R. Crisler J. Inorg. Nuclear Chem. 1972 34 3263. " R. D. Baybarz and H. K. Adair J. Inorg. Nuclear Chem. 1972,34,3127. " J. H. Burns and R. D. Baybarz Inorg. Nuclear Chem. Letters 1972,8,423. " S . Siekierski and I. Fidelis J. Inorg. Nuclear Chem. 1972 34 2225." H. D. Harman J. T. Peterson W. J. McDowell and C. F. Coleman J . Inorg. Nuclear Chem. 1972 34 1380 284 W. E. Smith and J. M. Winfield thus appears that this rule holds good for the heavy actinides as it does for the lanthanides. 4 The Titanium Group Titanium.-Compounds of the type Ti(biX)X have attracted some attention in recent years as they may contain five-co-ordinate Ti. Work reported last year suggested that this was not the case and an X-ray structure of Ti(acac)Cl, provides confirmatory evidence. The compound is a C1-bridged centrosym-metric dimer (6).57 X-Ray work has shown that TiCl,(NCH) has a cis con-figuration not trans as was suggested from its vibrational spectrum.58 Other work on Ti'" illustrates again the lability of its complexes in and the similarity of MeTiC1 to TiC1,.60 ,'Ti ( I = $ 7.3 % abundance) and 49Ti (1 = $ 5.5% abundance) n.m.r.have been used to examine tetrahalides in solution.59a The results are similar to those obtained from previous spectro-scopic work as monomeric TiX,(X = C1 or Br) and rapid exchange between TiCl and TiBr are indicated. A "F n.m.r. study of halide ligand redistribution between TiC1 and TiF in 1,2-dimethoxyethane indicates that all possible species in the series TiCl,-,F,(biL) can be formed but that isomers with a minimum number of Cl ligands trans to oxygen are favoured. This contrasts with previous work in THF and steric interactions between cis C1 and 0 atoms (THF) are deemed to be re~ponsible.~'~ MeTiCl reacts with Et,NCl in CH2C1 to give dark-violet light-brown or deep-blue salts depending on the mole ratio of reactants.60a Structures for the anions are formulated from their i.r.spectra as [MeCl,TiCl,TiCl,Me]-, [C13MeTiC1,TiC1,Me]2- and [MeTiClJ- respectively. The n.m.r. and i.r. spectra of MeTiCl,(biL) (biL = X'CH2CH,X2 where X',X2 are OMe NMe, or 5 7 N. Serpone P. H. Bird D. G. Bickley and D . W. Thompson J.C.S. Chem. Comm., 5 8 G. Constant J. C. Daran and Y . Jeannin Actu Cryst. 1971 B27 2388. 5 9 ( a ) R. G. Kidd R. W. Matthews and H. G. Spinney J. Amer. Chem. SOC. 1972 94, 6686. (b) R. S. Borden P. A. Loeffler and D . S. Dyer Inorg. Chem. 1972 11 2481. 6 o (a) R. J. H. Clark and M. Coles Chem. Comm. 1971 1587. (b) R. J. H. Clark and A. J. McAlees Inorg. Chem. 1972 11 342; J.C.S. Dalton 1972 640. 1972 217 The Transition Elements 285 SMe) complexes have been interpreted on the basis of rner configurations with the 'harder' X group trans to Me; m e r e fac exchange occurs readily and a twist mechanism is proposed to explain this.Reaction of MeTiCl,(biL) with 0 at room temperature gives the corresponding MeOTiCl,(biL) complexes which show similar behaviour.60b Little information is available about the solid-state structures of TiCl com-plexes but two X-ray structures of complexes with N-donor ligands have been reported this year.61 In the complex with NN-bis-(6-methyl-2-pyridylmethyl)-methylamine Ti"' has a distorted octahedral environment with a rner configur-ation (7). A similar configuration exists in [TiCl,py,]py and variations in the Ti-C1 and Ti-N bond distances are observed.Steric crowding about Ti appears to be responsible for the distortions observed in (7) but there is no simple Me T N - 7 explanation for the variable bond distances in the py complex although steric factors may be important. In py solution an e.p.r. study suggests that the most abundant species is [C12py2TiC1,Tipy,C1 3 an edge-sharing bioctahedral dimer with py ligands cis to the C1-bridges and a Ti-Ti distance of ca. 340 pm.62 The electronic spectrum of Ti2+ ions isolated in single-crystal NaCl is that expected for a d2 ion in an octahedral field. Values of Dq and B derived from the 77 K spectrum are 852 and 572 cm- ' re~pectively.~~ ZirconiumandHafnium.-In some of the work on these elements this year similarities to Ti chemistry are apparent.A vibrational study of MC14,2NOC1 compounds suggests that they should be formulated as [NO+],[MC162 -1 salts, like the Ti compound.64 Heats of formation of MC1,,2POC13 (s) are 88.6 (Zr) and 98.2 (Hf) kJ mol- l . The values are comparable with that reported for the Ti analogue last year and these compounds are also completely dissociated in the vapour phase.65 Stereochemical information on solid Hf(biX) species has been obtained using I8'Ta as a probe. Nuclear quadrupole interactions involving "'Ta were derived by measuring the differential perturbation in the angular correlation of 6 1 6 2 6 3 6 4 6 5 R. K. Collins M. G. B. Drew and J. Rodgers J.C.S. Dalton 1972,899; R. K. Collins and M. G. B. Drew Inorg. Nuclear Chem. Letters 1972 8 975. S.G. Carr and T. D. Smith J.C.S. Dalton 1972 1887. W. E. Smith J.C.S. Chem. Comm. 1972 1121. J. MacCordick C. Devin R. Perrot and R. Rohmer Compt. rend. 1972,274 C 278. E. K. Krzhizhanovskaya and A. V. Suvorov Russ. J . Inorg. Chem. 1971 16 1355, 1789 286 W. E. Smith and J. M. Winfield the y-y cascade of "'Ta fed by the /I decay of '"Hf. For the compounds where biX = N-benzo yl-N-phenylhydrox ylamine or N-nitroso-N-phenylhydroxylamine (cupferron) two "'Ta sites are observed in each case and it is suggested that isomeric configurations may be present. For biX = tropolone a rapid inter-conversion between isomeric forms is suggested and when CHCl is included in the lattice interaction between CHCl molecules and the ligand aromatic rings is proposed.66 The structural chemistry of Zr sulphates a field in which there has been recent activity has been reviewed,67 and further work relating to Zr molybdate gels, which are cation exchangers has been reported.68 Refluxing the gels in 1 4 M -HCl gives microcrystalline ZrMo,O,(OH),(H,O) whose X-ray structure comprises [Zr0,'9(OH),"q02"] pentagonal bipyramids and distorted cis-[MoO,(OH)(H,O)] octahedra.The units are cross-linked to give a three-dimensional network and one of the 0 atoms has the trigonal planar ZrOMo, co-ordination geometry. The crystalline form shows no ion exchange properties. 5 The Vanadium Group Vanadium.-Mass spectrometric studies have been reported on vanadium oxides and VOF3 .69 Species identified in the vapour over V,OS at 1000-1200 K include V,Ol0 and V,08 whereas VO, VO and V were found over V,O at 2270K.69" Following the detection of polymeric species in MF vapours (see last year's report) it has now been found that a similar situation obtains for VOF .Dimeric species were identified in its vapour at ambient temperature^.^" V0,XC (X = F or C1) anions have been isolated for the first time. They were prepared as their Ph4M+ (M = P or As) salts and CZv symmetry is indicated from their i.r. spectra.70 Vanadium oxides are reduced by liquid Li to the metal. This reacts with nitrogen which is present in the molten Li to give various products, e.g. V3N VN or Li,VN4.7' Stereochemistry of V 0 3 + and V 0 2 + complexes has been the subject of several reports. X-Ray work7 on two V03+ peroxo-complexes has shown that the geometry about Vv in [VO(O2),NH3]- is a distorted pentagonal pyramid with the terminal 0 atom axial and in [VO(O,)(dipicolinate)(H,0)]- is distorted pentagonal bipyramidal with 0 and H20 ligands occupying axial positions.The geometry of the former anion is very similar to that in [CrO(O,)py]. The X-ray structures of two VIVO(biX),L species have been reported; in both cases L is 6 6 P. Boyer A. Tissier J. I. Vargas and P. Vulliet Chem. Phys. Letters 1972 14 601 ; P. Boyer A. Tissier and J. I. Vargas Inorg. Nuclear Chem. Letters 1972 8 813. 6 7 I. J. Bear and W. G. Mumme Rev. Pure Appl. Chem. (Austral.) 1971,21 189. '* A. Clearfield and R. H. Blessing J. Inorg. Nuclear Chem 1972 34 2643. 69 ( a ) M. Farber 0. M. Uy and R. D. Srivastava J . Chem. Phys. 1972 56 5312; (b) ' O E.Ahlborn E. Diemann and A. Muller J.C.S. Chem. Comm. 1972 378. " C. C. Addison M. G. Barker and J. Bentham J.C.S. Dalton 1972 1035. " R. E. Drew and F. W. B. Einstein Inorg. Chem. 1972 11 1079; Acta Cryst. 1972, A. J. Edwards and D. R. Lloyd J.C.S. Chem. Comm. 1972 719. A28 S86 The Transition Elements 287 cis to the terminal 0 atom with the biX ligands mutually cis.73 The first species,73a the [VO(OX),(H,O)]~ - anion was previously formulated as five-co-ordinate because there was no i.r. evidence for ligated H,O. Its structure is similar to the six-co-ordinate anion [V0,(0x),]~ - whose sttucture was reported last year. It has been shown previously from i.r. spectroscopic work that VO(acac),L (L = substituted pyridine) complexes may have cis or trans configurations depending on the nature of the pyridine substituent.The structure of the complex where L = 4-~henylpyridine,~~~ however indicates that previous assignments should be reversed. A number of compounds of the type VO(S,PX,) have been isolated and their spectroscopic and magnetic properties depend on the nature of X. When X = Me Ph or OEt monomeric square-pyramidal structures are indicated but for X = F or CF the compounds appear to contain V-0 V chains.74 The crystal structure of V(S,CMe) contains two types of VSB dodecahedron, corresponding to the classes I d and V of the Hoard and Silverton notation. The I d type (rnrnrnrn chelation) has been found previously for V(S,CPh) (reported last year) but the V type (rnrngg chelation) which is unfavourable energetically, has apparently not been observed before in an MSs 1.r.and molar polarization measurements suggest that V(dpm),X (X = C1 or Br) have a trans configuration in the solid state but that in solution they exist in equilibrium with the cis form. The concentration of the latter increases with increasing dielectric constant of the solvent. This contrasts with the Ti" analogues which are exclu-sively cis and it is suggested that for V" steric factors play a greater role in determining the structure owing to the smaller central atom. Reaction of V(biX),Cl (biX = acac or dpm) with FeCl or SbCl gives [V(biX),]+Y-(Y = FeC1 or SbC1,) which are apparently the first well-characterized cationic complexes of V1v.76 The X-ray structure of K,[V(CN),],2H20 shows it to contain isolated V(CN)74- anions with approximate D, symmetry.There is no significant difference between axial and equatorial V-C bonds (214.4 and 214.9pm, respectively) and these distances are longer than those of other 3d cyano-complexes. The anion is believed to be the first example for d block elements of an MX group where X is not F and the anion appears to persist in A very thorough study of the magnetic properties of V(urea),13 has been made which has included crystal structure determinations at room temperature and at ca. 90 K. The compound is isomorphous with the Ti"' analogue (reported in 1970) and the cation has D symmetry at both temperatures. A temperature-7 3 ( a ) G. E. Form E. s. Raper R. E. Oughtred and H. M. M. Shearer J.C.S. Chem. Comm.1972 945; (b) M. R. Caira J. M. Haigh and L. R. Nassimbeni Inorg. Nuclear Chem. Letters 1972 8 109; J. Znorg. Nuclear Chem. 1972 34 3171. 7 4 R. G. Cavell E. D. Day W. Byers and P. M. Watkins Znorg. Chem. 1972 11 1591. " L. Fanfani A. Nunzi P. F. Zanazzi and A. R. Zanzari Acta. Cryst. 1972 B28 1298. 7 6 R. B. VonDreele and R. C. Fay J. Amer. Chem. SOC. 1972,94,7935. 77 R. L. R. Towns and R. A. Levenson J . Amer. Chem. SOC. 1972,94,4345. 7 8 B. N. Figgis and L. G . B. Wadley J.C.S. Dalton 1972 2 182 288 W. E. Smith and J. M. Winfield dependent distortion along the three-fold axis exists there being a small elonga-tion at low temperature and a zero or slight compression at room temperature. Magnetic susceptibility and anisotropy data (80-300 K) are interpreted on the basis of a 3T1s ground state with 1 = 45cm-' A = 450crn-' and k = 0.5.78 A study of the electronic spectra of VX (X = C1 Br.or I) crystals at various temperatures has shown that while the general features expected for isolated V2+ ions are observed additional sharp fine structure and intense spin-forbidden bands are the result of antiferromagnetic exchange between V" centres." Niobium and Tantalum.-Combustion calorimetry of Nb and Ta penta-alkoxides suggests that average M-0 bond energies for these compounds are in the range 4 1 8 4 3 8 kJ mol- Rather surprisingly there is little difference between Nb and Ta.80 Exchange processes in these compounds have been studied using 'H n.m.r. spectroscopy.81 Scrambling among terminal RO-groups occurs faster than scrambling between terminal and bridging.The activation energy for the latter process is fairly constant (ca. 4 2 4 8 kJ mol- ') although for Ta derivatives the activation entropy depends on the size of R. Possibly steric factors are important.81' M(OMe) are weaker Lewis acids than the corresponding halides and M(OMe),L (L = N- or 0-donor ligand) are in equilibrium with [M(OMe),] in solution.81b MF,-,,(NEt,) (n = 1 or 2) which from their i.r. spectra are believed to be polymeric via F-bridges are formed from reactions of MF with Me,SiNEt . Analogous reactions with Me3SiC1 give chlorofluorides which were precipitated from solution as py complexes.82 The i.r. spectrum of matrix-isolated NbF has been assigned on the basis of C, symmetry,83 although from work on other pentahalides D3, symmetry might have been expected.Isomeric complexes of MCl with MeNCS have been reported which from their i.r. spectra appear to be N- or S-bonded isomers. They can be interconverted at their melting points. TaCl reacts with PhNCS to give a compound formulated as Cl,(S)Ta 9 N(Ph) = CCl .84 Further compounds in the series NbCl -,,Me, have been identified from reactions between NbCl and Me,Zn. NbC13Me was isolated pure and forms complexes NbCl,Me,L (L = 0- N- P- or S-donor ligand) in which the Me groups are trans. NbC1,Me was not obtained pure but its complexes were isolated. The decomposition pressure of NbBr, corresponding to the equilibrium (5 - x)NbBr,(s) NbBr,(s) + (4 - x)NbBr,(g) at a given temperature is much lower than that for NbCl, suggesting that the former compound is significantly '9 W.E. Smith J.C.S. Dalton 1972 1634. ** V. I. Telnoi I. B. Rabinovich B. I. Kozyrkin B. A. Salamatin and K. V. Kirianov, Doklady Akad. Nauk S.S.S.R. 1972 205 364. ( a ) C. E. Holloway J. Co-ordination Chem. 1971 1 253; (6) L. G. Hubert-Pfalzgraf, J. Guion and J. G. Riess Bull. SOC. chim. France 1971 3855. '' J. C. Fuggle D. W. A. Sharp and J . M. Winfield J.C.S. Dalton 1972 1766. 83 N. Acquista and S. Abramowitz J. Chem. Phys. 1972,56 5221. 8 4 H. Bohland and F.-M. Schneider Z . Chem. 1972 12 28 63. G. W. A. Fowles D. A. Rice and J. D. Wilkins J.C.S. Dalton 1972 231 3 The Transition Elements 289 more stable.86 E.p.r. signals due to NbOClS3- and NbOCl,(H20)2- have been observed from solutions of NbCl in conc.HCl. NbC16,- can be isolated from solution (for example as the Cs’ salt) but no signal for this species was observed. Reduction of NbV by Zn in HC1 or HC1,EtOH gives solutions containing [NbOC1,LI2- (L = H 2 0 or EtOH). Considerable electron delocalization into the equatorial C1 pn-orbitals is suggested for these specie^.^' The first simple complexes of Ta”’ have been prepared by MeCN reduction of TaCl . Diamagnetic [TaCl,(NCMe),] has been isolated for which structure (8) is proposed from its spectra and by analogy with [WCl,(py),] . From MeCN N c1 N dl solutions of this complex diamagnetic TaCl,(biL) (biL = bipy or phen) and paramagnetic Ta(dibenzoylmethanate) were isolated. 13 A number of papers concerning (M6X12)A+ clusters have appeared.89 The crystal structures of [(Nb6C1 2)c16]2 - and [(Nb,Br ,)C1,l2 - have been deter-mined.89a,b Nb-Nb (301.8-307.2 pm) and Nb-C1 (terminal) distances are longer and shorter than those in the (Nb6Cll 2)2’ analogue as expected.Similarly, an n.q.r. study of [(Nb6Cll,)C1,]2- is consistent with the availability of 1k for Nb-Nb bonding.*’‘ (pyH),[(M6Br,,)C1,] undergo an exothermic irreversible rearrangement at 473 K to give (pyH),[(M,Br,Cl,)Br,] in which six Br ligands in two trigonal cluster planes are exchanged by Cl.89a.d M.c.d. studies89e on (M,Xl,)”+ (n = 2,3 or 4) clusters have been used to revise previous assignments of their electronic spectra. A bonding scheme is proposed which includes the effects of spin-orbit coupling and which has a different ordering of orbitals than in the scheme due to Cotton and Haas.The green-brown cations [(Me6C6)3M3X6]+ (x = c1 or Br) are readily oxidized to dipositive cations a 6 A. D. Westland and D. Lal Canad. J. Chem. 1972,50 1604. 8 ’ 8 8 D. G . Blight R. L. Deutscher and D . L. Kepert J.C.S. Dalton 1972 87. 8 9 ( a ) B. Spreckelmeyer and H. G. von Schnering 2. anorg. Chem. 1971 386 27; (b) F. W. Koknat and R. E. McCarley Inorg. Chem. 1972 11 812; (c) P. A. Edwards, R. E. McCarley and D. R. Torgeson Inorg. Chem. 1972 11 1185 ; ( d ) B. Spreckel-meyer C. Brendel M. Dartmann and H. Schafer Z . anorg. Chem. 1971 386 15; ( e ) D. J. Robbins and A. J. Thomson J.C.S. Dalton 1972 2350; cf) R. B. King, D. M. Braitsch and P. N. Kapoor J.C.S. Chem. Comm. 1972 1072. D. P. Johnson and R. D. Bereman J . Inorg.Nuclear Chem. 1972 34 679 290 W. E. Smith and J. M. WinJield which are isolated as PF6- or BPh,- salts. They are diamagnetic therefore their simplest molecular formula is [(Me,&)6M6X 214+ and the cations could be regarded as C6Me derivatives of [(M6X’ 2)X26]”- ~lusters.*~f The superconducting intercalation complexes of TaS and pyridine derivatives that were reported last year are representative of a large class of intercalates involving MX (M = Ta Nb V Hf Zr or Ti; X = S or Se) and aliphatic or aromatic amines NH hydrazine and substituted hydrazines or Bu3P.” Superconductivity is observed when the parent dichalcogenide is superconducting. The critical temperatures depend on the intercalate but are insensitive to the separation of the superconducting planes up to 5700 pm.’Oa The X-ray photo-electron spectra of NbSe and TaS with amine intercalates suggest that electron transfer from N to the metallic layers occurs possibly to a band derived from metal d, orbitals.90b Other materials with superconductor properties that have been reported are Li,Ti,.,S (0.1 < x < 0.3) which has the hexagonal Ti,S, ~trucfure,’~~ and rhombohedra1 Mo6-,M,S6 (M = Cu Ag Zn Cd Mg Sn or Pb).’ l b The transition temperatures of these materials are generally higher than those found in layered sulphides.6 The Chromium Group Chromium.-From a study of electron attachment and compound formation in H,-O,-N flames values for the electron affinities of CrO and HCrO of 390 and 229 kJ mo1-l respectively have been deduced.’ A study of the reactions of molecular oxygen evolved from the aqueous decomposition of K,CrO suggests that at least some of it is in an excited singlet state.This is probably the first example of singlet 0 production from a transition metal oxygen-containing ~ornplex.’~ Reduction of CrO,’- in the presence of perfluoropinacol leads to the formation of [CrVO{ (CF,),C(O)C(O)-(CF,),),I- which can be isolated as Cs’ K’ or Et,N’ salts. The compounds are remarkably stable to reduction and to hydrolysis and it is suggested that the bidentate ligand may stabilize other unusual oxidation states.’, The most widely studied Cr” species is probably CrO,,-. This year further salts of this anion KSrCrO and KBaCrO, have been reported. Their structures are derived from P-K,SO and the corresponding MnV salts are is~structural.~~ The electronic spectra of CrV and MnV doped in various phosphate and vanadate hosts have been interpreted in terms of the effects of the anion site size and possible 90 (a) F.R. Gamble J. H. Osiecki M. Cais R. Pisharody F. J. DiSalvo and T. H. Geballe Science 1971 174 493; H. Fernhndez-Morhn M. Ohstuki A. Hibino and C. Hough ibid. p. 498; ( 6 ) B. Bach and J. M. Thomas J.C.S. Chem. Comm. 1972, 301 ; (c) R. Schollhorn R. Ruthardt and A. Weiss 2. Nuturforsch. 1972 27b 1273, 1275 1277 1278. 9 1 (a) H. E. Barz A. S. Cooper E. Corenzwit M. Marezio B. T. Matthias and P. H. Schmidt Science 1972 175 884; (b) B. T. Matthias M. Marezio E. Corenzwit, A. S. Cooper and H. E. Barz ibid. p. 1465. 9 2 W. J. Miller J. Chem. Phys. 1972 57 2354.93 J. W. Peters J. N. Pitts jun. I. Rosenthal and H. Fuhr J. Amer. Chem. SOC. 1972, 94 C. J. Willis J.C.S. Chem. Comm. 1972 944. 9 5 R. Olazcuaga J.-M. Reau and G . LeFlem Compt. rend. 1972,275 C 135. 94 4348 The Transition Elements 29 1 Jahn-Teller distortion of CrV.' Further examples of CrIV stabilized as fluoro-complexes are Li,CrF (NazSnF6 structure) and A'tkF (A = Ba or Sr BaSiF, structure ; A = Mg Ca or Cd LiSbF structure ; A = Ni or Zn VF3 ~tructure).'~ Many papers dealing with Cr"' complexes have been concerned with the study of reactions and equilibria in solution. Some papers are dealt with in the Reaction Mechanisms Report.* Another interest has been the spectra and magnetic properties of exchange-coupled Cr"' species.98 The [Cr@(OAC),(H,0)3]+ cation is a particularly suitable model to study such effects.Transitions observed in the 690-750 nm region of its polarized electronic spectrum have been identified as originating from different ground-state spin levels and a highly structured band system between 330 and 365nm is assigned to double excitation of low-energy doublet states.980 The magnetic susceptibility of [(NH,),CrOCr(NH,),]-X,,H20 in which the Cr-0-Cr group is linear (see last year's report) has been redetermined because previous work had been performed using samples con-taminated with [(NH,),Cr(OH)Cr(NH3),(OH)]X,. The paramagnetic suscepti-bility in the range 50-300 K has now been fitted to an isotropic exchange model with S = 3 and J = 450cm-1.98b X-Ray work on [Cr(glycinate),OH] has shown the presence of a planar Cr(OH),Cr unit with LCr-0-Cr = 98.2'.Low-temperature (4.2-100 K) magnetic susceptibility data are consistent with previous work at higher temperatures and with the postulate formulated for Cu"(OH),Cu" complexes that 2J decreases with increasing M-0-M angle.g 8c The X-ray structures of two Cr" complexes with N(SiMe,) ligands provide further examples of unusual stereochemistries that can be produced by this ligand." [Cr{ N(SiMe,),),(THF),] prepared from CrC1 and LiN(SiMe,) in THF has a trans square-planar structure. The bond distances suggest that little or no N+ Cr x-bonding is present although the CrNSi and CrOC units are planar. The pseudo-tetrahedral C3" structure suggested previously (see 1970 report) for [Cr(NO) { N(SiMe,),),] has been confirmed.In this compound the CrNSi units are planar; the bond distances suggest considerable N - + Cr It-bonding and that NO is a It-acceptor. The structure of antiferromagnetic CsCrC1 features face-sharing [Cl*CrCl+], chains in which there is a small Jahn-Teller distortion from trigonal symmetry. The single-crystal polarized electronic spectra of CsCrC1 and of Cr" doped in CsMgCl contain spin forbidden bands whose intensities depend on the Cr" concentration and a band strongly polarized along the hexagonal crystal c axis 9 6 J. B. Milstein J. Ackerman S. L. Holt and B. R. McGarvey Inorg. Chem. 1972 11, 9 7 G. Siebert and R. Hoppe 2. anorg. Chem. 1972,391 113 126. 98 (a) L. Dubicki and P. Day Inorg. Chem. 1972 11 1868; (6) E. Pedersen Acra Chem. Scand. 1972 26 333.(c) D. J. Hodgson J. T. Veal W. E. Hatfield D. Y. Jeter and J. C. Hempel J . Co-ordinarion Chem. 1972,2 1 . 99 D. C. Bradley M. B. Hursthouse C. W. Newing and A. J. Welch J.C.S. Chem. Comm. 1972 567. 1178. 'Inorganic Reaction Mechanisms' ed. J. Burgess (Specialist Periodical Reports) The Chemical Society London Vol. 2 1972 and Chapter 1 1 of this volume 292 W. E. Smith and J. M . Winjield at ca. 2A. Both features are attributed to magnetic coupling between Cr" centres.' O0 Molybdenum and Tungsten.-Interest in eight-co-ordinate compounds and com-plexes formed by the tetrahalides of these elements continues and further consolidating work has appeared this year. Oxidation oftetrakis 5,7-disubstituted-8-quinolinolato (biX) compounds of W" (see last year's report) by Cl, Br, or HClO at room temperature or by HbiX above room temperature produces violet paramagnetic [W(biX),]Y (Y = C1 Br CIO, or biX)."' The compounds disproportionate in aqueous or alcoholic base to give W(biX) and Wvl but they are more stable than the analogous Nb" compounds.Their e.p.r. spectra imply distorted dodecahedra1 structures similar to the W" compounds. The reactions of Ag,M(CN) with alkyl iodides have been re-investigated independently by two groups.'02 Compounds of the type [M(CN),(CNR),] (R = Me Et Pr" Pr', But C,H Ph,CH or Ph,C) which are diamagnetic non-electrolytes are obtained. The X-ray structure of [Mo(CN),(CNMe),] shows an MoC triangular dodecahedron with CN groups (Mo-C, = 217.7 pm) at the n-donor positions and CNMe groups (Mo-C, = 214.8 pm) at the n-acceptor positions.'02"*b The vibrational spectra of the other products suggest that they have similar struc-fures.lozc An additional product formed from the reaction of Ag,Mo(CN) with Bu'I is the Mo" compound red-orange [Mo(CNBu'),I]I in which Mo has monocapped trigonal prismatic geometry with I above one of the square faces (9).Bond distances are Mo-I 286.2; Mo-C, (trans to I) 206; Mo-CC, (cis to I) 212 pm.lo2' 0 = MO (9) 0 =Br l o o G. L. McPherson T. J. Kistenmacher J. B. Folkers and G. D. Stucky J . Chem. Phys. 1972 57 3771. l o ' R. D. Archer W. D. Bonds jun. and R. A. Pribush Inorg. Chem. 1972,11 1550. I o 2 ( a ) M. Novotny D. F. Lewis and S. J. Lippard J . Amer. Chem. Soc. 1972,94 6961 ; (b) F. H. Can0 and D. W. J.Cruickshank Chem. Comm. 1971,1617; (c) R. V. Parish and P. G. Simms J.C.S. Dalton 1972 2389; ( d ) D. F. Lewis and S. J. Lippard Inorg. Chem. 1972 11 621 The Transition Elements 293 Another example of seven co-ordination in Mo chemistry is provided by X-ray work on [MoBr,(PMe,Ph),] (10) which is a mono-capped octahedron of ClV ~ymrnetry."~" Three Br ligands (Mo-Br = 256.0pm) occupy the uncapped face three P atoms (Mo-P = 258.0pm) the capped face and the fourth Br (Mo-Br = 242.5 pm) the capping position. Apparently the co-ordination geometry found in these complexes is determined by the steric requirements of the ligands. Seven co-ordination is suggested for WCl,(NMe,), which dissociates in solution to give [WC13(NMe3),]+ and Cl-,'03b and for WCl,(PMe,Ph),-(NCMe).lo3' They provide further examples of the ease with which an additional ligand may be added to MX,L complexes.MX,(NCMe)2 are widely used to prepare other complexes by ligand exchange under mild conditions but with more vigorous conditions reduction can occur. For example WC1,(NMe3) can be formed from WCl,(NCMe) and NMe (see also tantalum section). It has a low magnetic moment and a polymeric structure is indicated.'03b WCl,L (L = PR, or AsR,) may be prepared directly from WCl, by Zn-Hg reduction in CH,Cl, or THF in the presence of L (two moles). A related procedure is used for mer-Other complexes containing MI" include Mo(biX),X (biX = acac oxine or N-substituted salicylaldimines ; X = C1 or Br) prepared from MoCl,(NCMe), or MoX,(py) polymeric [MoC14(4,4-bipy)] for which a cis-MoC1,N2 configuration is suggested,' 03e and W(NCS),(py) and [M(NCS),bipy] which like A,[M(NCS),] and A[W(NCS),] have N-bonded isothiocyanate groups.lo4 K,WCI or a solution of WCl reduced by RLi in THF are good reagents for olefin synthesis for example via a cis deoxygenation of vicinal diols.The reason is believed to be the ready formation of Wvl-O bonds in these systems.'05 Mo,(02CCF,) which is prepared from Mo,(OAc) and a CF3C02H-(CF,CO),O mixture has the expected dimeric D, structure. The Mo-Mo (209.0pm) and C-0 distances are not significantly different from those in the acetate. The Mo-Mo distance in [pyMo(O,CCF,),Mopy] is 212.9 pm and LMo-Mo-N = 171.0 '. Corresponding v(Mo-Mo) frequencies in the Raman spectra of the solid compounds are 397 (trifluoroacetate) and 367 cm-(bis py adduct) compared with 406cm-' in the acetate.Formation of M0,-(02CCF3),L2 in donor solvents (L) is implied as both v(Mo-Mo) and the energy of the lowest electronic transition decrease with increasing donor ability of the solvent.'06 Rather surprisingly carboxylates of Wn have proved to be difficult to prepare. Dimeric compounds analogous to the Mo" series have not been [WOCl,L,]. Io3' l o 3 ( a ) M. G . B. Drew J. D. Wilkins and A. P. Wolters J.C.S. Chem. Comm. 1972 1278; (6) D. G . Blight D. L. Kepert R. Mandyczewsky and K. R. Trigwell J.C.S. Dalton, 1972 313; ( c ) A. V. Butcher J . Chatt G. J. Leigh and P. L. Richards ibid. p. 1064; ( d ) A. van den Bergen K. S. Murray and B. 0. West Austral. J . Chem. 1972,25,705; ( e ) W.M. Carmichael and D. A. Edwards J . Znorg. Nuclear Chem. 1972 34 1181. l o 4 T. M. Brown and C. J. Horn Inorg. Nuclear Chem. Letters 1972 8 377; C. J. Horn and T. M. Brown Znorg. Chem. 1972 11 1970. K. B. Sharpless and T. C. Flood J.C.S. Chem. Comm. 1972 370; K. B. Sharpless, M. A. Umbreit M. T. Nieh and T. C. Flood J . Amer. Chem. SOC. 1972 94 6538. l o 6 F. A. Cotton and J. G. Norman jun. J . Co-ordinarion Chem. 1971 1 161 ; J . Amer. Chem. SOC. 1972,94 5697 294 W. E. Smith and J. M. Winjield isolated and the products appear to be polymeric [W(O,CR),] or impure [W3(02CMe)90].'07 The chemistry of Mo W and Re with dinitrogen and related ligands continues to expand trans-[M(N,),(diphos),] (M = Mo or W) being useful intermediates!" Reactions of RC(0)Cl with trans-[W(N,),(diphos),] give [Cl,(diphos),-W=N-NH-C(O)R] from which HCl can be reversibly removed to give chelated [Cl(diphos),W(N,COR)].The chelate ring appears to have structure (1 la) rather than (1 lb) which has been suggested for related Re compounds (see 1971 report). [MX,(diphos),(N,H,)] (X = C1 or Br) and [WCl(N,H,)(diphos),]Y (Y = BPh or C10,) are formed from trans-[M(N,),(diphos),] and HX and are regarded as models for part of the N fixation process. Diamagneticorganoimido-complexes of Mo [(12) is regarded as one of the four possible canonical forms] are formed from [MoOCl,(PMe,Ph),] and 1 -aryl-2-benzoylhydrazines. O9 PMe,Ph I Molybdenum and Tungsten 0x0-compounds and Related Topics.-It is possible to include only a small fraction of the work that has appeared in this field.The isomorphous series of heteropolyanions [(H20)M1(*+)0,M2("+)0,(W or Mo) 03J(' - are valuable hosts to study magnetic effects between two isolated centres (MI M2 = Fe3+ Co2+ or Co3+). M'('"+)'occupies a distorted octahedral site M2("+) a tetrahedral site and the two ions are 0x0-bridged with /'-O-M2 ca. 125 O and M1-M2 cu. 330 pm. When S' # S2 the low-temperature susceptibilities follow a Curie law characteristic of IS' - S2( and l o ' F. A. Cotton and M. Jeremic Synrh. Inorg. Metal-org. Chem. 1971 1,265; G . Holste lo' J. Chatt G. A. Heath and G. J. Leigh J.C.S. Chem. Comm. 1972 444; J. Chatt, and H. Schafer Z . anorg. Chem. 1972 391 263. G. A. Heath and R. L. Richards ibid. p. 1010. J. Chatt and J. R. Dilworth J.C.S. Chem.Comm. 1972 549 The Transition Elements 295 the individual g values at high temperatures the susceptibilities tend towards another Curie law characteristic of the sum of the susceptibilities of the uncoupled ions whereas at intermediate temperatures little change in the susceptibilities is observed.' ' Crystal structures of simple 0x0-complexes reported include that of [Mo~O,(O-C,H,O~)~]~ -. Two cis-MoO,(biX) groups are linked uia an oxo-bridge a very distorted octahedral co-ordination about Mo being completed by two additional bridges involving an 0 atom from each o-C6H402 ligand to give an [O,MoO,MoO3] arrangement.' ' 1,2-Dimethoxyethane undergoes an oxygen abstraction reaction with WSC1 to give a dinuclear product (13) with an unsymmetrical bridge (W-0 = 172 and 226pm).The compound may be regarded as a donor-acceptor complex between(biL)Cl,(S)WO and WSCl . ' I 2 Crystal structures of several Mov'-peroxo-complexes have been determined ' ' including [MOO(O~)~(OP(NM~,),)L] (L = H 2 0 or py) which are pentagonal bipyramids with axial 0 and L groups. The compounds have been used to per-form an elegant oxidation of secondary amides R'C0.N(R2)SiMe, to hydrox-amic acids. ' ' 3b [R'C(b).N(R2)0],koO2 complexes are formed initially from which the free acids are readily liberated. A study by 19F n.m.r. spectroscopy of the reactions of WOF,- or MoOF,-(NCMe) with EtOH in MeCN suggests that F ligands cis to the M=O group are preferentially replaced by OEt ligands. Ligands trans to M=O might have been expected to be more labile and (pd)n-bonding is offered as an explanation of the observed 'cis' effect.' ' A thermodynamic and kinetic study of the reaction of 8-quinolinol with MoO,(dien) (dien = diethylenetriamine) yielded results identical with previous work with Although the complex is well characterized 1 LO 1 1 1 1 1 2 1 1 3 114 L.C. W. Baker V. S. Baker S. H. Wasfi G. A. Candela and A. H. Kahn J. Amer. Chem. SOC. 1972 94 5499. L. 0. Atovmian V. V. Tkachev and T. G. Shishova Doklady Akad. Nuuk S.S.S.R., 1972 205 609. D. Britnell M. G. B. Drew G. W. A. Fowles and D. A. Rice J.C.S. Chem. Comm., 1972 462. (a) J.-M. LeCarpentier R. Schlupp A. Mitschler and R. Weiss Acra Crysr. 1972, B28 1278 1288; (6) S . A. Matlin and P. G. Sammes J.C.S. Chem. Comm. 1972 1222. Yu. A.Buslaev Yu. V. Kokunov V. A. Bochkaryova and E. M. Shustorovich, J . Inorg. Nuclear Chem. 1972 34 2861 296 W. E. Smith and J. M . Winfield in the solid state it rapidly hydrolyses in aqueous solution giving Moo,'- and dienH + . The W analogue behaves similarly.' Several other papers have dealt with oxine and related ligands.'I6 Four distinct compounds of composition [MoO(oxine),],O have been reported from reactions of Mo"' with Hoxine under various conditions. It is suggested that the isomerism is due to differing configurations of the terminal 0 ligands.'16" 1 1 Complexes between MoV and oxine its mercapto- or amino-analogues or 3,4-dimercaptotoluene in DMF have been identified by e.p.r. spectroscopy. The expected order of ligand binding strength - S - > -0- > -NH2 is found and in the thiol complexes there is considerable electron delocalization.116b Information about electron transfer processes in Mo-oxine complexes has been obtained from an electrochemical study in DMSO. Reduction of MoVIO,-(oxine) occurs in two one-electron steps with solvent attack on the intermediates displacing oxine. The Mo" species formed catalytically reduces any excess oxine present. Mov,O,(oxine) is reduced in two reversible one-electron steps giving Mo~-Mo'~ and then Mo'; dimers. The latter intermediate decomposes to give a Mo" species identical with that produced from MoV1. Oxidation of Mov203(oxine) is an irreversible one-electron process producing a MoV1-MoV dimer which decomposes and is further oxidized to MovlO,(oxine) .' A series of dinuclear Mo"' complexes with bipy or acac ligands has been pre-pared from Mo,O,Cl,(H,O) .Their spectroscopic and magnetic properties indicate that Mo0,Mo groups are present. From similar evidence Mo,03(ox),-(H,O), is thought to contain Mo(OH)(O)Mo groups linked by bridging ox ligands. These is no evidence for terminal 0 ligands the presence of which had been suggested previo~sly."~ A compound of composition Mo(S2CNPrn) is produced from Mo" acetate and NH,S2CNPr" but its X-ray structure indicates that C-S bond cleavage has occurred to give a compound which contains Mo" (14) with a carbene type linkage (C-Mo = 206.6pm). The Mo-Mo distance (270.7 pm) and LMo-Sbridge-Mo (72.3 ") indicate direct interaction."' Much 'Is R. S. Taylor P. Gans P. F. Knowles and A.G. Sykes J.C.S. Dalton 1972 24. ( a ) W. Andruchow jun. and R. D. Archer J . Inorg. Nuclear Chem. 1972 34 3185; (6) G. R. Lee and J. T. Spence Inorg. Chem. 1972,11,2354; ( c ) A. F. Isbell,jun. and D. T. Sawyer ibid. 1971 10 2449. L. Ricard J. Estienne and R. Weiss J.C.S. Chem. Comm. 1972 906. '17 P. C. H. Mitchell and R. D. Scarle J.C.S. Dalton 1972 1809. ' I The Transition Elements 297 of the foregoing work has been undertaken with the expressed aim of investigating model systems for Mo-containing enzymes which have again been reviewed. '' Although none of the models can be considered to be definitive they have gener-ated much interesting co-ordination chemistry. 7 The Manganese Group Manganese.-The general chemistry of manganese in its oxidation states above two and the properties of manganese porphyrin complexes have been reviewed.'20 Manganate-(vI) and -(v) have attracted some interest this year.y-Irradiation of KMnO at 77 K produces an e.p.r. active species [MnV'0,2- . - MnV"On7 - 2 n ] in which there is interaction between Mn042- and a neighbouring species (MnO,- or MnO,'). On warming to room temperature a second species, probably 03- is formed.lZ Manganate-(vr) and -(v) may be observed in molten alkali metal nitrates nitrites or hydroxides. Whether MnV' or MnV species are stabilized depends on the identity of the alkali metal cation(s) and on the con-centration of other anions added to the melt.'22 For example in K,Na nitrate melts Mn0,2- is stabilized in the presence of OH- whereas MnO,,- is stabilized in the presence of 022- or 02- anions.'22u The MnV',MnV system is thus a convenient probe for comparing melt properties.Attempts to grow single crystals of [Mn(bipy),](ClO,) led instead to the isolation of [(bipy)2Mn(0)2Mn(bipy)2] (ClO,),. X-Ray work indicated that this is a Mn"' Mn" compound with the expected Jahn-Teller distortion for Mn"' producing a lengthening of the Mn-"(axial) relative to the Mn-N(equatoria1) bonds. The compound is antiferromagnetic and a superexchange mechanism is suggested.' 2 3 The chemistry of anhydrous metal nitrates has been extended by the preparation from N205 and MnF of a thermally unstable Mn"' derivative, which is believed to be high-spin. Adduct formation occurs with N205 {formu-lated as [NO,+][Mn(NO,),-]} and also with bipy phen MeCN or Ph,PO.The X-ray structure of Mn(N03) bipy shows the presence of seven-co-ordinate (approximately pentagonal bipyramidal) Mn"'. Axial positions are occupied by N (bipy) and a unidentate NO group equatorial positions by symmetrically and unsymmetrically co-ordinated bidentate NO ligands and the remaining N. ' 24 The M(S2C-) units in tris-NN-dialkyldithiocarbamato complexes usually have D symmetry but X-ray work has shown that this is not the case for Mn(S2CNEt2) The structure may be understood in terms of a tetragonal 120 W. Levason and C. A. McAuliffe Co-ordination Chem. Rev. 1972,7,353; L. J. Boucher, 12' S. Subramanian and M. T. Rogers J . Chem. Phys. 1972 57 2192. 1 2 2 ( a ) B. J. Brough D. A. Habboush and D. H. Kerridge Inorg. Chim. A m 1972,6,366; ( b ) R .B. Temple and G. W. Thickett Austral. J . Chem. 1972 25 6 5 5 ; ( c ) H. Lux and E. Renauer Z . anorg. Chem. 1972 390 303. P. M. Plaksin R. C. Stoufer M. Mathew and G . J. Palenik J . Amer. Chem. SOC., 1972 94 2121. D. W. Johnson and D. Sutton Canud. J . Chem. 1972 50 3326; F. W. B. Einstein, D. W. Johnson and D. Sutton ibid. p. 3332. 12' ( a ) P. C. Healy and A. H. White J.C.S. Dalton 1972 1883; ( 6 ) R. M. Golding E. Sinn, and W. C. Tennant J . Chem. Phys. 1972,56,5296. R. C. Bray and J . C. Swann Structure and Bonding 1972 11 107. ibid. p. 289 298 W. E. Smith and J. M . Winfield distortion superimposed on D symmetry arising from Jahn-Teller distortion of the 5E,(0,) ground state. This contrasts with previous work on Mn(acac) in which no distortion was found and a dynamic Jahn-Teller effect postulated.Interestingly the e.p.r. spectra of Mn(S,CR,) doped in their Co"' analogues contain no signals which can be obviously attributed to the Mn"' centres. The observed spectra are tentatively suggested to arise from electron delocalization to or near the ligand S atoms.'25b Mn" complexes continue to be widely studied. Mn(SP(Ph),NP(Ph),S) has been examined as a possible model for biologically important d5MS4 complexes, e.g. iron(1rr) rubredoxin. An approximately tetrahedral MnS core (Mn-S = 242.7-245.5pm) is evident from its X-ray structure and peff = 5.75 BM is consistent with an ,A ground state. Its electronic absorption spectrum is very similar to that of Mn2+ doped in ZnS but its emission spectrum shows a pro-nounced red shift.This contrasts with Mn2+ZnS and some flexibility of the s, environment in the complex is suggested.12 Other work includes a single-crystal e.p.r. study of [Mn(O(Me,N)2POP(NMe,)~O) ,] (ClO,) where a highly 'ionic' metal-ligand interaction is indicated,' 27 and an examination of the reduction of Mn(acac) by primary amines.'28 Normally [Mn(acac),(L or en)] (L = RNH,) are obtained but when L = CH,:CHCH,NH the product is [Mn(acac),L] a centrosymmetric dimer with octahedral Mn0,N co-ordination. The structure is analogous to [Co(acac),L] (L = H,O or cyclohexylamine). Technetium and Rhenium.-This year as last halogen compounds of these elements have proved a fruitful field of study. The reaction of Tc metal with C1, at 573 K has been re-investigated with the results that Tc0,Cl and TcOCl were isolated.TcC1 which with Tc03C1 has been reported previously from this reaction was not isolated and alternative routes to this compound would seem to be desirable. A good route to Tc0,Cl is from TcCl and O2 at 723 K and its vibrational spectrum is similar to Re0,Cl and Tcz07 suggesting a similar molec-ular s t r ~ c t u r e . ' ~ ~ The crystal structure of ReOCl shows that two types of square-pyramidal ReOCl molecules (both having Re-0 = 163 Re-Cl = 226 pm) are present.I3' They are weakly associated via Re - - - Cl contacts (355 and 365 pm) trans to Re-0 into dimers or endless chains. The absence of M-0 - - - M contacts contrasts with the structure of WOCl, but the dimeric units are similar to those found in WSX (X = C1 or Br).The formation of ReOC1,L complexes is now well e~tab1ished.l~~ X-Ray work (on ReOC1,. 0. Siiman M. Wrighton and H. B. Gray J . Co-ordination Chem. 1972 2 159. 12' G. M. Woltermann and J. R. Wasson Chem. Phys. Letters 1972 16 92. ''' Y . Nishikawa Y. Nakamura and S. Kawaguchi Bull. Chem. SOC. Japan 1972 45, 155; S. Koda S. Ooi H. Kuroya Y. Nishikawa Y. Nakamura and S. Kawaguchi, Inorg. Nuclear Chem. Letters 1972 8 89. l Z 9 A. Guest and C. J. L. Lock Canad. J . Chem. 1972,50 1807; A. Guest H. E. Howard-Lock and C. J. L. Lock J. Mol. Spectroscopy 1972,43 273. 130 A. J. Edwards J.C.S. Dalton 1972 582. ' 3 1 (a) P. W. Frais and C. J. L. Lock Canad. J . Chem. 1972,50,1811; (6) C . G. Barraclough and D. J. Kew Austral. J . Chem. 1972 25 27; ( c ) D.A. Edwards and R. T. Ward, J.C.S. Dalton 1972 89 The Transition Elements 299 (L = Et,O Me,CO or MeCN) indicates that co-ordination occurs trans to the 0 ligand although with NH ammono-lysis occurs to give [ReO(NH,),] which appears to be O-b~-idged.'~'' In non-co-ordinating solvents and in the vapour phase both ReOCl and OsOCl, appear to be monomeric. Square-pyramidal structures are favoured although the decision is not A re-investigation of the properties of A,ReOCl (A = Rb or Cs) indicates that they contain spin-paired ReV. The products previously reported in the literature appear to have been contaminated with ReC1,'- or ReO4-.l3 The disproportionation of ReIV to Re"' and ReV occurs readily in air but from re-actions of p-ReCl under rigorously anhydrous and O,-free conditions ReIV complexes may be isolated e.g.cis-ReCl,L (L = MeCN or py) and truns-ReCl,(PPh,),. Even so the reactions are complex and reduction to Re"' occurs also.133 One of several papers describing the use of boron halides to effect halogen-exchange reactions describes the isolation of Re,Br6C1 from Re,Cl, and BBr . Redistribution reactions occur on sublimation or in a mass spectro-meter and X-ray work on one product suggests that it is Re,Br,Cl. These compounds contain the triangular Re group and replacement of C1 by Br occurs preferentially in the terminal positions.'34 The crystal structure of [Pt11(NH3)4]2[ReV203(CN)8] confirms the structure of the anion previously suggested from solution work (see 1970 report). The cyano-ligands are believed to be C-bonded and bond distances in the linear OReOReO skeleton are 191.5 (bridge) and 169.8 (terminal) pm.These may be compared with Re-0 = 178.1 pm in tran~-ReO,(CN),~- whose structure has been redetermined. '' Arylimido-complexes of Mo are described in the Mo section and related work on Re compounds has led to two interesting reactions. The well-known ReV-arylimido-compounds e.g.[ReCl,(NPh)(PPh,),] are conveniently prepared from reactions of phosphinimines RN=PPh (R = Ph or PhCO) with ReOCl,(PPh,),. The route is useful since [ReCl,(NC(O)Phf(PPh,),] cannot be prepared by other methods and this work further demonstrates the analogy between ReV=O and X = O . [OsOCl,(PPh,),] and ArC(O)N=PPh give [OsCl,(NAr)-(PPh,),] .Io9 trans-[ReCl,(NMe)(PPh,R),] (R = Ph Me or Et) are deprotonated by py to give [ReCl,(N=CH,)py(PPh,R),] from which the original compounds are regenerated with HCl.These appear to be the first examples of transition-metal complexes containing the - N=CHZ ligand although its C-substituted derivatives are well known. Similar reactions using NEt and excess PR give mer-[ReCl,(N=CH,)(PR,),] in which -N=CH2 is trans to the unique PR, ligand. Linear Re-N-C groups are suggested in these corn pound^.'^^ and spectroscopic 1 3 2 J. E. Fergusson and J. L. Love Austral. J . Chem. 1971 24 2689. 1 3 3 R. A. Walton Inorg. Chem. 1971 10 2534. 1 3 4 M. A. Bush P. M. Druce and M. F. Lappert J.C.S. Dalton 1972 500. 1 3 ' R. Shandles E. 0. Schlemper and R. K. Murmann Inorg. Chem. 1971 10 2785; 1 3 6 J. Chatt R. J.Dosser and G. J. Leigh J.C.S. Chem. Comm. 1972 1243. R. K. Murmann and E. 0. Schlemper ibid. p. 2352 300 W. E. Smith and J. M. Winfield 8 The Iron Group Iron.-A simple preparation of the ferrates Rb,FeO and Cs,FeO and an improved preparation of K,FeO and BaFeO have been reported. 3 7 The K Rb and Cs salts are isostructural with P-K,SO and the magnetic susceptibi-lities are field-independent and obey the Curie-Weiss law. The new fluorides FeSnF613* and MFeF,13' (M = Na K Rb or Cs) have been prepared. The hydrolysis of dilute Fe"' chloride solutions has produced a new structural form of B-Fe2O3 .I4' An attempt to prepare isocyanate complexes by treating K,Fe(CN) with oxonium salts in acetone led to the formation of new cyano-complexes.141 The reaction appears to be an acid-catalysed aldol addition of the acetone Fe(CN):- + 12Me,CO + 6R30+BF Fe(CNCMe,CH,COMe),(BF,), + 4BFT + 6R,O + 6ROH (R = Et or Pr) The reduction of p-0x0-bis[tetraphenylporphyriniron(~~~)] by Na-Hg in THF yields several products the first being a compound characterized by e.p.r., magnetic susceptibility and electronic spectra as the first Fe' porphyrin sodium-[phenylporphyriniron(~)].', The five-co-ordinate high-spin Fe"' substituted porphyrins known to have a distinct out-of-plane displacement of the Fe"' should on addition of a sixth ligand effecting the transition to the low-spin state, have no such displacement. Structural verification of this has long been delayed because suitable crystals of a six-co-ordinate low-spin Fe"' porphyrin were not available.The structure of such a compound bisimidazole [a,P,y,&tetraphenyl-porphyrinatoiron(~~~)] chloride has now confirmed this prediction. The structure of an iron@) analogue with piperidine in place of imidazole is also reported.143 Attempts to use cysteine as a model for the reactions of non-haeme iron proteins require the use of low temperatures and non-aqueous solvents to prevent rapid oxidation reactions but the corresponding penicillamine has two methyl groups in blocking positions which inhibit these reactions. The results of an investigation of the controlled oxidation of Fe" penicillamine complexes to Fe"' with H20, are reported. Vapour-pressure and gas-chromatograph studies of P-diketo-nates of Fe" indicate that in solution the tris chelates interact with the solvent only by van der Waals forces with no evidence of hydrogen bonding but the bis chelates have a specific solvent interaction presumably at the sites above and below the chelate ring.14' Dimeric dialkoxo-bridged Fe"' chelates of the form 1 3 ' R.J. Audette and J. W. Quail Znorg. Chem. 1972 11 1904. 1 3 * R. Hoppe V. Wilhelm and B. Muller Z . anorg. Chem. 1972 392 1. 1 3 9 G. Ellinger A. Funke P. Kleinert P. Roseman and W. Keilig 2. anorg. Chem., 140 H. Braun and K. J. Gallagher Nature 1972 240 13. l d l 14* 1 4 3 (a) D. M. Collins R. Countryman and J. L. Hoard J . Amer. Chem. SOC. 1972. 94, 144 L. G. Stadherr and R. B. Martin Inorg. Chem. 1972 11 92. 1972 393 193. M. Shaul and W. Beck Agnew Chem. Internat. Edn 1972 11 527. I. A. Cohen D.Ostfeld and B. Lichtenstein J . Amer. Chem. SOC. 1972 94 4523. 2066; (6) L. J. Radonovitch A. Bloom and J. L. Hoard ibid. 1972,94 2073. W. R. Wolf R. E. Sievers and G. H. Brown Znorg. Chem. 1972.11 1995 The Transition Elements 30 1 [biL,FeOR] (L = acac or dipivaloylmethane R = Me Et or Pr') have been prepared and characterized. They are weakly antiferromagnetic with similar electronic spectra to the monomers but with peaks at slightly higher energies. 146 A number of papers on tetrahedral FeX,- ions have appeared. The crystal structure of (MeNH,),FeBr gives the first structural evidence for the tetrahedral FeBr,- ion.',' The first single-crystal electonic spectra of RFeBr (R = EtPhH', NMe,' NHMe,+ NH,Me,+ NH,Me+) have been reported and assigned using a crystal-field calculation.The spin-orbit splittings are much smaller than for the isoelectronic ion MnBr,'- and these and other differences from the man-ganese spectra are explained in terms of a larger Jahn-Teller effect due to the higher charge on Fe111.'48 The luminescence of Et,NFeBr and a series of complexes with FeC1,- ions has been studied.I4' Although iron nitrosyl compounds were among the first nitroso-complexes to be discovered there has been little systematic study of them. A number of new complexes including Fe(S,CEt,),,XNO (X = Br I or NO,) were reported this year.'" In each case the unidentate ligands are in the cis conformation. The five-co-ordinate complex Fe(S,CNEt,),I has an Fe-I distance of 259 pm, demonstrating that the iodine is covalently bonded to the iron."' Much work on the crossover between high- and low-spin ground states of iron has appeared.The complexes FeLX (L = rneso-5,5,7,12,12,14-hexamethyl-1,4,8,1l-tetra-azacyclotetradecane) (X = NO- NO - NCS- or MeCN) provide the first examples of low-spin Fe" with predominantly aliphatic nitrogen co-ordination. If X = OAc- C1- Br- or I- the complex is high-spin demon-strating that the crossover is dependent on ligand field strength.', Work on a series of substituted tridithiocarbonate complexes indicates that the crossover is sensitive to electron withdrawal rather than steric effects.', The crystal struc-tures of two similar complexes one low-spin tris-( 1-pyrro1idinecarbodithioato)-iron(m) and the other high-spin tris-(N-methyl-N-pheny1dithiocarbamato)iron-(111) indicate that the geometry round the iron is similar but that there is a sig-nificant reduction in the Fe-S bond distance in the latter.ls4 The inadequacy of considering the ground-state crossover to be a simple ,T, to 6Al in Fe" has been demonstrated by Mossbauer studies.'55 The ground states which may be expected to occur including the areas of mixed spin states have been calculated for D systems plotting D against D4.lS6 A series of complexes giving examples 146 C.S. Wu G. R. Rossman H. B. Gray G. S. Hammond and H. J. Schugar Znorg. 14' G. D. Sproul and G. D. Stucky Znorg. Chem. 1972,11 1647. 148 149 C. D. Flint and P. Greenough J . Chem. Phys. 1972 56 5771. Chem. 1972 11 971. M. Vala P. Mongan and P. J. McCarthy J.C.S. Dalton 1972 1870. H.Buttner and R. D. Feltham Znorg. Chem. 1972 11 971. P. C. Healy A. H. White and B. F. Hoskins J.C.S. Dalton 1972 1369. R. R. Eley R. R. Myers and N. V. Duffy Inorg. Chem. 1972 11 1128. l S z J. C. Dabrowiak P. H. Merrell and D. H. Busch Inorg. Chem. 1972 11 1979. 5 4 P. C. Healy and A. H. White J.C.S. Dalton 1972 1163. l S 5 P. B. Merrithew and P. G. Rasmussen Znorg. Chem. 1972 11 325. E. Konig P. Giitlich and R. Link Chem. Phys. Letters 1972 15 302 302 W. E. Smith and J. M . Win3eld of both a 'T2 and 6 A equilibrium and mixed spin states has been reported.157 The nature of the ground state of the (bipy),Fe"' ion is again discussed and assigned for what appear cogent reasons to an E ground state.'58 Oxygen-bridged Fe"' dimers have been investigated by magnetic susceptibility, Mossbauer electronic and i.r.spectra. It is concluded that a ligand field model incorporating spin-spin interactions of pairs of high-spin Fe"' ions is superior to the Dunitz-Orgel MO model for these systems.'59 The origin of the colour in naturally occurring sapphires has been elucidated. Yellow sapphire contains chromophores consisting of Fe3 + ions and Fe3 +-O2 -Fe3 + pairs ; blue and green sapphires have bands due to Fe3+-02-Ti4+ and more complex Fe2+-02-Fe3+ species.'6o The nature of the defects in Fe -,O suggest a cluster with four vacant cation sites round the iron; increasing the iron content increases the size of the cluster.'6' Ruthenium and Osmium.-The new compound OsOF has been prepared in good yield by the reduction of OsOF on a hot tungsten filament.'62 The first osmium-oxygen complex,163 the first example of a stable nitroso metal por-phyrin rnesoporphyrin-IX dimethyl [esterato dinitrosyl ruthenium (II)],' 64 and [OsH,en,]ZnCl the first osmium hydride with only saturated nitrogen co-ordination' 6 5 have been prepared.The nitrogen-bridged dimer [Cl(NH3),-OS'~NNOS'~(NH,),]~+ is easily oxidized to the mixed valence dimer [H20(NH3),-Os"NNOs"'(NH,),] which is kinetically quite stable and has a complex electronic spectrum at quite low energies owing to exchange coupling between the metals.'66 The crystal structure of [Os(NH3),N2]C12 is similar to the corresponding ruthenium derivative but it has been more accurately defined. Only a small change in the bond length of the co-ordinated nitrogen compared with gaseous nitrogen is noted but there is a large change in i.r.stretching frequency. The nitrogen is both 6- and n-b~nded.'~' The reaction of [Ru(NH~)~],+ in base with nitric oxide appears to proceed through the attack of the nitric oxide on the ruthenium to yield the nitrogen complex [Ru(NH3),N2]+. There is a rapid reaction a quantitative yield and the method does not need an external reducing agent.'68 Studies of the heat of reaction of [Ru(NH,),H~O]~+ and [Ru(NH3),-H20I2+ with o-donors and n-acceptors shows that the Ru"' bonds more strongly 1 5 7 A. J. Cunningham J. E. Ferguson H. K. J. Powell E. Sinn and H. Wong J.C.S. ' 5 8 R. E. De Simone and R. S. Drago Inorg. Chem. 1972 11 668. 1 5 9 H. J. Schugar G. R. Rossman C. G. Barraclough and H. B.Gray J. Amer. Chem. 160 J. Ferguson and P. E. Fielding Austral. J . Chem. 1972 25 1371. 1 6 1 1 6 * W. E. Falconer R. D. Burbank G. R. Jones W. A. Sunder and M. J. Vasile J.C.S. Dalton 1972 2155. SOC. 1972 94 2683. N. N. Greenwood and A. T. Howe J.C.S.Dalron 1972 110 116 122. Chem. Comm. 1972 1080. B. E. Cavert K. R. Grundy and W. R. Rohr J.C.S. Chem. Comm. 1972 60. 164 T. S. Srivastava L. Hoffman and M. Tsutsui J. Amer. Chem. SOC. 1972,94 1385. J. Maln and H. Taube Inorg. Chem. 1972 11 2403. 1 6 6 R. H. Magneson and H. Taube J. Amer. Chem. SOC. 1972 94 7213. J. E. Fergusson T. L. Love and W. T. Robinson Inorg. Chem. 1972 11 1662. 16' S. Pel1 and J. N. Armor J. Amer. Chem. SOC. 1972 94 686 The Transition Elements 303 to a-donors Ru" to rr-acceptors. The replacement of one NH group by H,O in [(RU(NH,),),N,]~+ decreases the heat ofbinding of the N by 6 kcal mol-1.169 Dinitrogen bridging between ruthenium and boron is demonstrated in a series of complexes ((Ph3P)3Ru(H2)N,),B,oH8.The yellow crystalline solids are either stable in air or oxidize slowly and the nitrogen triple bond is retained in the complexes even on treatment with NaBH, HCl KCN or MeCN."' The reaction [RuClNO(diars)]Cl + 2N,- -* [RuN,Cl(diars),] + N + N,O has been followed by isotopic labelling studies. An intermediate ring structure of the form is postulated. The azide complex is thermally stable and can be converted into the nitrogen complex by treatment with HC1-MeOH a reaction known for Ru"' but not previously for Ru".'~' The crystal structure of two similar phosphorus bridged ruthenium complexes gives examples of both bent and linear Ru-N-0 bonds.0 0 1 \ N / c1 \ / N / / RU -c1 c1 c1 Ru- Ru 'p' 'N \ 0 (15) 0 9 N P L \ / \ / Ru=Ru / \ / \ L P N \ 0 The Ru-N-0 bond angle in (15) is 16V but it is clear that rr-bonding does occur in the complex. 72 Significantly more metal-metal bonding occurs in (16) than in (15) as measured by the Ru-Ru distance. In (NH,),[RuNOCl,] the Ru-N-0 bond is again bent. l7 The series of compounds [Ru(NH,),(NO)L]X, (L = C1- Br- NCO- N3- OH- NH, or MeCO-; X = C1- Br- I - or 169 G. D. Watt J . Amer. Chem. SOC. 1972 94 7351. 170 W. H. Knoth J . Amer. Chem. SOC. 1972 94 104. "' P. G. Douglas and R. G. Feltham J . Amer. Chem. SOC. 1972,94 5254.1 7 ' R. Eisenberg A. P. Gaughan C. G. Pierpoint J. Reed and A. J. Schultz J . Amer. 1 7 3 J. T. Veal and D. J. Hodson Znorg. Chem. 1972 11 1420. Chem. SOC. 1972 94 6240 304 W. E. Smith and J. M. Winjield ClO,-) has been investigated by m.c.d. electronic absorption and i.r. spectra. The possibility of Ru"'N0 is ruled out the species are Ru"NO+.' 74 The X-ray photoelectron spectra of a series of complexes of Os Rh Ir and Pt are reported and caution in the interpretation of this type of result counselled. Only results from very similar molecules can reasonably be compared.' 75 The diffuse reflectance spectra at 4.2 K of OsF,- and IrF6- are reported and inter-preted.' 7 6 Charge delocalization on [Ru"(NH,),L]~+ ions by spectral and n.m.r. techniques has been studied.' 7 7 9 The Cobalt Group Cobalt-A new series of fluorides MCo"'F (M = Cs Rb Na or Li) has been reported. The Cs salt fluorinates benzene directly to give C6F as the product.' 7 8 Cs2CoF6 and the new compound Rb2CoF are ferromagnetic. ' 79 Ba2[Co,(CN),,],13H20 is the first air-stable crystal reported which contains the CO,(CN),~~- group. X-Ray studies of the compound have revealed that the structure is similar to Mn2(CO),,. The axial Co-CN bond is longer than the equatorial one in contrast to the manganese case and the infrared assignments are consequently altered.' 8o The novel CO,C~,~ - ion with the cobalt in approxi-mately tetrahedral geometry and bridged by two halides is reported.18' The species Co(N,) has been isolated and its i.r. spectrum obtained by matrix-isolation techniques.' 82 The reduction of a vitamin B12 analogue lY19-diethoxy-carbonyltetradehydrocorrincobalt(n) gives two products.A one-electron re-duction gives a very stable Co' species and a two-electron reduction gives a Co" species with two extra electrons on the ring so that the unusual pattern of oxida-tion states of the cobalt + I1 --* + I -+ + I1 appears.'83 Mono-dipeptide com-plexes of the type [Co(NH,),a,a,] are reported. The dipeptide is terdentate and planar having lost an amide proton.'84 The [Co"'dienI3+ moiety has been used to investigate the formation of peptides using glycine esters and glycine glycine esters. In one product [Co(dien)Gly-Gly-Gly-Gly-ORX]' + at low and neutral pH the cobalt is bonded to the glycines through the terminal amines and the oxygen of the carboxy-group in the third position is blocked so that the complex 1 7 4 A.F. Schreiner S. W. Lin P. J. Hauser E. A. Hopcus D. J. Hamm and J. D. Gunter, 1 7 5 G. J. Leigh and W. Bremner J.C.S. Dalton 1972 1216. 17' G. C. Allen G. A. M. El-Sharkaway and K. D. Warren Inorg. Chem. 1972 11 51. 1 7 7 (a) A. M. Zwichel and C. Creutz Inorg. Chem. 1971,10,2395; ( 6 ) D. K. Lavellee and 17' A. J. Edwards R. G. Plevey I. H. Sallomi and J. C. Tatlow J.C.S. Chem. Comm., Inorg. Chem. 1972 11 880. E. B. Fleischer J. Amer. Chem. SOC. 1972 94 2583. 1972 1028. J. W. Quail and G. A. Rivett Canad. J. Chem. 1972,50 2447. l S o (a) G. L. Simon A. W. Adamson and L. F. Dahl J. Amer. Chem. SOC. 1972 94, 7655; (6) L. D. Brown K. N. Raymond and S .2. Goldberg ibid. 1972 94 7664. I' * W. Harrison N. L. Paddock J. Trotter and J. N. Wingfield J.C.S. Chem. Comm. 1972, 23. J. K. Burdett. M. A. Graham and J. J. Turner J.C.S. Dalton 1972 1620. I. G. Browning R. D. Gillard J. R. Lyons P. R. Mitchell and D. A. Phipps J.C.S. Dalton 1972 1815. '*' N. S. Hush and J. S. Woolsey J. Amer. Chem. SOC. 1972 94 4107 The Transition Elements 305 must isomerize to give a metal-nitrogen rather than metal-oxygen bond before the third position is filled.'85 The macrocycle 3,3-dimethyl-1,5,8,1l-tetra-aza-cyclotridecane was prepared by a template reaction on Ni2+ and the nickel complex reduced with NaBH to give the fully unsaturated ligand. The nickel was removed with-cyanide and on addition of a Co"' solution the Co"' complex was formed.'86 Zwitterion com-plexes of the type M[Co(diphos),(CN),]X (M = Mn" Fe" Co" Ni" or Zn") have been prepared.The Co"' is linked with M" by a CN bridge.'87 Co" com-plexes of 2,2'-dithiodipyridine and 4,4'-dithiodipyridine are reported for the first time.'88 The structure of Co(NO)(S,CNMe,) has a bent Co-N-0 bond but the NO groups are disordered lying above one or other of the Co-S bonds of the same ligand. ' 89 Two low-spin five-co-ordinate Co" complexes [Co(diphos),-ClISnC1 and [Co(diphos),Cl]SnCl ,C,H,Cl are square-pyramidal and dis-torted towards trigonal-bipyramidal respectively. The spectra of both are very similar indicating the difficulties of assigning the structure of five-co-ordinate Co" complexes from spectral data.'" A spectral and magnetic study of Co" ions in distorted environments showed that these properties are rather insensitive to the distortion parameter Cp.' ' A low-spin calculation for tetragonally distorted octahedral systems suggests a ,Al ground state in cobalt(I1)phthalocyanine. 192 The e.p.r. spectrum of (Et,N),CoCI and CoCl, - doped into (Et,N),ZnCl, demonstrates that the axis of the ions is reoriented at the phase change." A discussion of the electronic Raman spectra of Co2+ in Co,GeO has appeared. 194 The three geometrical isomers of [Co(dien)J3+ have been resolved. The trans-isomer is the most stable and the u-cis and trans-isomers have been resolved into optical isomers by diastereoisomer formation. The trans-isomer exists as two optical isomers because of the non-planarity of the chelate rings and a discussion of the nature of the puckering of the rings and its optical consequences was given.' 95 Rhodium and Iridium.-The blue cation [Ir(MeNC),]+X (X = C1 PF, or BF,) associates with unidentate ligands (L = various solvents CO or MeNC) when irradiated with visible light to form a five-co-ordinate complex which dis-sociates in the dark back to the starting materials. The forward reaction appears to be the first proven example of the photochemical formation of a metal-ligand Y. Wu and D. H. Busch J . Amer. Chem. SOC. 1972 94 4115. lE6 N. F. Curtis and G. W. Reader J.C.S. Dalton 1972 1453. '" P. Rigo B. Longato and G. Favero Znorg. Chem. 1972 11 301. '" J. R. Ferraro B. B. Murray and N. J. Wieckowicz J . Znorg. Nuclear Chem. 1972, 34 231.J . H. Enemark and R. D. Feltham J.C.S. Dalton 1972 718. 1 9 0 J. K. Stalick P. W. R. Corfield and D. V. Meek J . Amer. Chem. SOC. 1972 6195. '" M. Gerloch J. Lewis and R. Richards J.C.S. Dalton 1972 980. L. M. Englehardt and M. Green J.C.S. Dalton 1972 755. 1 9 3 ( a ) G . E. Shankle J. N. McElearney R. W. Schwartz A. R. Kampf and R. L. Carlin, J . Chem. Phys. 1972,56 3750; ( b ) J. N. McElearney G. E. Shankle R. W. Schwartz, and R. L. Carlin ibid. 1972 56 3755. 19' J. A. Konigstein P. A. Grunberg J. T. Hoff and J. M. Preudhomme J . Chem. Phys., 1972 56 354 306 W. E. Smith and J. M . Winjield bond. Diphos does not react with the cation in the dark but on exposure to light the five-co-ordinate complex Ir(MeNC)(diphos) is formed. Five-co-ordinate d81r' complexes generally lose a ligand in oxidative additions but all five donor atoms are retained and no such reaction occurs in this case.196 There are very few examples of nucleophilic attack on the nitrogen of a co-ordinated nitrosyl although it is well known for carbonyl groups. The cationic nitrosyls [IrCI,NOL,]+(L = PPh or AsPh,) react with alcohols ROH to give neutral Ir"' complexes containing alkyl nitrites IrCl,(RONO)L (R = Me Et or Pr).19' A series of dioxygen complexes RhX(O,)(PPh,),(RNC) (X = C1 Br or I ; R = But; X = C1 R = cyclo-C6Hl or p-MeC6H4) RhCl(O,)(AsPh,),(Bu'NC), and [Rh(02)(PPh,),(ButNC),]C1 greatly extends the range of complexes of this type known. They are relatively thermally stable some hold oxygen reversibly, others do not.198 The synthesis of the first Rh' and Rh" porphyrins of interest as Co" analogues and as possible catalysts has been reported.'98 The photochemical dissociation of [Rh1"(NH,),XI2 + by irradiation of the ligand-field bands proceeds by two pathways giving as major product either [Rh(NH3),H,0]3+ if X = C1 or [Rh(NH3),(H2O)XI2+ if X = I ; with bromide both are found.The possibility that the different yields are due to different intersystem crossing yields or to different populations of singlet and triplet excited states has been ruled out. The most likely explanation is that two different triplet states of differing geometries can form one with an elongated Rh-X bond and one with an elongated Rh-NH bond."' The decomposition of [Ir"'-(NH3),N3] was postulated to go through a nitrene intermediate (see last year's report).Complex ions formed by reaction of HSO,- or C1- and the nitrene have now been isolated and characterized as [Ir1"(NH3),NH,0S03]2+ and [Ir"'-(NH,),NH2C1I3+ A new preparation of IrF has been reported.,' The m.c.d. and electronic absorption spectra of Ir4+ in Cs,ZnCI have been examined and in the light of the evidence a different interpretation of the spectra of Ir4+ is given.,' The luminescence spectra in eight different solvents of Ir"' complexes show both a solvent effect and a method of separating charge-transfer and ligand-localized transition^.^'^ A study of 31P n.m.r. in the complexes MX,L,(M = Rh or Ir, X = C1 Br or I L = tertiary phosphines) corrects a number of literature assignments. ,05 I g 5 F. R. Keene and G.H. Searle Znorg. Chem. 1972,11 148. '96 W. M. Bedford and G . Rouschias J.C.S. Chem. Comm. 1972 1224. 19' C. E. Reed and W. R. Roher J.C.S. Dalton 1972 1243. 198 A. Nakamura Y. Tatsuno and S. Otsuka Znorg. Chem. 1972 11 2058. I g 9 B. R. James and D. V. Stynes J . Amer. Chem. SOC. 1972,94 6225. 2 o o T. L. Kelly and J. F. Endicott J. Amer. Chem. SOC. 1972 94 278. 2 0 1 * 0 2 W. A. Sunder and W. E. Falconer Znorg. Nuclear Chem. Letters 1972 8 537. 203 S. B. Piepho J . R. Dickinson J. A. Spencer and P. N. Schatz J. Chem. Phys. 1972, *04 R. J. Watts G. A. Crosby and J. L. Sansregret Inorg. Chem. 1972 11 1475. ' 0 5 B. E. Mann C. Masters and B. L. Shaw J.C.S. Dalton 1972,704. B. C. Lane J. W. MacDonald F. Basolo and R. G . Pearson J. Amer. Chem. SOC., 1972 94 3786.57 982 The Transition Elements 307 10 The Nickel Group Nickel.-A complete series of complexes with macrocyclic ligands in which Ni" is co-ordinated to four nitrogens and the number of unsaturated nitrogens varies from one to four has been prepared (17)-(20). (19) is well known and the others were prepared by oxidation or reduction. The oxidation and reduction reactions of the series were investigated electrochemically and oxidation states ranging from 111 to 0 were found. In acetonitrile (17) undergoes only a one-electron reduction whereas (18) (19) and (20) undergo a second reduction. It is postulated that the first reduction involves addition of an electron to the ring, the second an addition to the Oxidative dehydrogenation of a known macrocycle produced a new type of unsaturation (21)207 and the template synthesis of a ligand containing two azo-groups gave the novel product (22).208 The encapsulating 'tripod' like ligands MeC(CH,PPh,) and MeC(CH2PEt2)3 are normally bidentate in nickel complexes but with nitrite ions the ligands become terdentate and an Ni-NO bond is formed.1.r. and electronic spectra and magnetic data gave no positive indication of the nature of the nickel nitrosyl bond but an X-ray crystal structure of [NiMeC(CH2PEt2)3NO]BF shows that the nickel is pseudo-tetrahedral with the Ni-NO bond linear. The complex is 206 E. K. Barefield G . V. Lovecchio N. E. Tokel E. Ochiai and D. H. Busch Znorg. 2 0 7 C. J. Hipp L. F. Lindoy and D. H. Busch Znorg. Chem. 1972 11 1988. 2 0 8 N. W. Alcock and P.A. Tasker J.C.S. Chem. Comm. 1972 1239. Chem. 1972 11 283 308 W. E. Smith and J. M . Winfield therefore formulated as Ni' with an NO+ group as a ligand.," An X-ray structure of the Nil complex [NiMeC(CH,PPh,),]I shows that the nickel is pseudo-tetrahedral ;'lo the C1 and Br complexes have been prepared. A series of Ni"' complexes with syn-2-benzoylpyridine oxime and syn-2-phenacyl-pyridine oxime ligands is reported and the difficulties of establishing the exist-ence of this oxidation state are discussed.212 The NilV complexes [Ni(PPh,),-(SnR,),]CI (R = Ph or Me) have been prepared. Preliminary X-ray studies indicate an octahedral structure with a trans-trans-trans arrangement of the The reactivity of the oxygen complex NiO,(Bu'NC) with a series of reagents demonstrates differences in the behaviour of co-ordinated and free oxygen and characterizes the nature of the reaction.214 The preparation of an aziridine complex with the nickel co-ordinated to the nitrogen of the aziridine ring and a novel ring-opening mechanism of the co-ordinated species are re-ported.215 The new oxide Li,NiO has been prepared.216 A high-power i.r.laser has been used to induce an octahedral-tetrahedral transition in a Ni" complex. This is the first example of a laser-stimulated chemical change involving an electronic excited state rather than a vibrational one.217 A convenient method of carrying out a magnetic titration developed from the Quinke method for measuring magnetic susceptibility has been applied to the elucidation of the intermediates in the formation of Ni(en),,+ complexes.21 The species Ni(0,) and O,Ni(O,) identified in matrix-isolation studies are the first examples of binary molecular oxygen complexes of the transition metals.Variable-concentration diffusion-controlled warm-up and isotope-labelling experiments confirm the existence of the species and show that the oxygen is co-ordinated side-on in contrast to the results for Ni(N,) where the nitrogen is bonded end-on.'lg A study of the matrix-isolated species produced when N U , and NiF gases are mixed with CO and N and quenched in solid argon has led to the first report of carbonyl halides of nickel NiC1,CO and NiF,CO. The i.r. stretching frequency of the CO is the highest yet observed suggesting that it is almost entirely o-bonded.2o An X-ray study of the boron hydride transition-metal complex (Me,N),-Ni(B ,H 2)2 is reported. There are eight metal-boron bonds with two different distances fusing the two Bl,Hl groups in a slightly open staggered position to '09 D. Berglund and D . W. Meek Inorg. Chem. 1972 11 1493. ' l o P. Dapporto G. Falloni S. Midollini and L. Sacconi J.C.S. Chem. Comm. 1972, 1161. 'I1 L. Sacconi and S. Midollini J.C.S. Dalton 1972 1213. ' I ' R. S. Drago and E. I. Baucom Inorg. Chem. 1972 11 2064. 2 1 3 P. E. Garrou and G. E. Hartwell J.C.S. Chem. Comm. 1972 881. 2 1 4 S. Otsuka A. Nakamura Y. Tatsuno and M. Miko J . Amer. Chem. SOC. 1972 94, 3761. 'I5 C. A. Root B. A. Rising M. C. Van Derveer and C . F. Hallmuth Inorg. Chem. 1972, 11 1489. R. Rieck and R. Hoppe 2.anorg. Chem. 1972 392. 193. K. J. Ivin R. Jamison and J. J. McGarvey J. Amer. Chem. SOC. 1972,94 1763. G. R. Grayhill J. W. Wrathall and J. L. Ihrig Inorg. Chem. 1972 11 723. ' I 7 2 1 9 H. Huber and G. A. Ozin Canad. J. Chem. 1972 SO 3746. "O C. W. DeKock and D. A. VanLeirsburg J. Amer. Chem. SOC. 1972,94 3235 The Transition Elements 309 each other.221 A theory of n.m.r. contact shifts as applied to tetrahedral Ni" complexes shows that the usual T-' temperature dependence would not be expected to hold and the available data is analysed on the new theory.222 An X-ray photoelectron study of nickel dithiolate complexes indicates that the Ni atom is best represented as Ni' not Satellite lines ('shake up' peaks) occur in the X-ray photoelectron spectrum of paramagnetic compounds and in particular are associated with the 2p photoelectron emission from nickel com-pounds.These peaks do not occur in the diamagnetic square-planar compounds and can be used to differentiate between the two.224 Palladium and Platinum.-Complexes of platinum and mercury are usually formulated as having a Pt-Hg bond although this has not been confirmed by structural evidence. A series of complexes of the type (Me,Ph),PtX,HgY, (X = Cl Br or I ; Y = Cl or Br) has been prepared and the structural analysis of one of them (X = Y = C1) shows that the platinum and mercury are bonded by a double halogen bridge with no evidence of direct metal-metal bonding. The platinum is in square-planar and the mercury in distorted-tetrahedral co-ordination. The i.r.spectra of the complete set of compounds suggest that the bonding between the metals is of a similar type in each case.22s A new set of Pto complexes with arylated polytertiary phosphines has been reported.226 The dinuclear species Pt,S,P4(CF3), is formed from the reaction of PtCl, or K2PtC1 with (CF3),PS2H. On the basis of mass spectra and "F n.m.r. studies it is formulated as (23),,,' i.e. two S groups have been eliminated in the course of the reaction. Most sulphur-bridged Pd complexes show low reactivity to organic halides but polymeric sulphur-bridged palladium complexes of 1,2-ethanedithiol and 1,3-propanedithiol react readily with organic halides. Many of the products are as yet unidentified.228 The X-ray crystal structure of 2 2 1 2 2 2 223 2 2 4 2 2 5 2 2 6 2 2 7 2 2 0 L.J. Guggenberger J . Amer. Chem. Soc. 1972 94 114. B. R. McGarvey J . Amer. Chem. SOC. 1972 94 1103. S. 0. Grim L. J. Matienzo and W. E. Swartz J . Amer. Chem. Soc. 1972,94 51 16. L. J. Matienzo W. E. Swartz and S. 0. Grim Znorg. Nuclear Chem. Letters 1972 8, 1085. R. W. Baker M. J . Braithwaite and R. S. Nyholm J.C.S. Dalton 1972 1924. R. B. King and P. N. Kapoor Znorg. Chem. 1972,11 1525. R. G. Cavell W. Byers E. D. Day and P. M. Watkins Znorg. Chem. 1972 11 1599. L. Cattalini J. S. Coe S. Degetto A. Dondoni and A. Vigato Znorg. Chem. 1972,11, 1519 310 W. E. Smith and J. M. Winfield Pt2(S2CC6H4p-C3H,)4 shows this compound to be the first example of a discrete Pt'l molecule with a Pt-Pt bond.229 The first structures of metal-metal bonded dithioline complexes of both Pd and Pt are reported,,' and the first structure of an azide-bridged Pd dimer (Ph,As),Pd,(N,) shows that the bridging is through one terminal nitrogen of the azido-gr~up.~~' There are few derivatives of unidentate amines known for Pd and Pt mainly due to preparative difficulties.The use of the bridged complex M2X4(PMeJ)2, has facilitated the preparation ofcomplexes MX,(NMe,) and Pr,NMX,(NMe,), (MX = PtCI PtBr or PdBr).232 A range of cationic Pd" isocyanide complexes has been ~repared.~ 33 The first all-oxygen co-ordinated sulphoxide of palladium, Pd(di-isoamylsulphoxide),(BF4)2 has been reported as one of a series of Pd" and Pt" complexes with S and 0 l i g a n d ~ . ~ ~ A novel series of hydroxo-bridged dimers has proved to be remarkably stable chemically resisting cleavage by tertiary phosphines under conditions which would easily cleave chloro-bridged species.235 Linkage isomerism in the hydride complexes L2PtHX (L = Ph,P; X = NO NCS CN or NCSe) was detected for NCS only.236 The product of the reaction of[PtF(PPh,),]HF with CS2 has beenshown tobe [Pt(S,CF)(PPh,),]-HF,.The CS has been inserted into the Pt-F bond.237 The new oxides Na,PtO and Na,Pt03 have been prepared2,* and a new series of compounds of formula PtCl,(SCN),,nH,O (x = 2,2.4 3.8 5.1 6.0; y = 2 1.6 1.2,0.9,0.5 resp) were identified from the action of liquid chlorine on Pt"(SCN) .239 The species Pd(N,) has been detected in matrix isolation There has been much work. on the conductivity of non-stoicheiometric platinum compounds in the solid state much of it directed towards Little's suggestion that conditions for high-temperature superconductivity could be found in materials of this type.The temperature dependence of the conductivity of K,.,,Pt(CN) ,1.8H20 is unusual in that a metal-insulator transition of the type previously found only in organic solids has been detected.,,' It seems likely that impurities play a large part in the conductivity of this type of platinum 2 2 9 J. P. Fackler J. Amer. Chem. SOC. 1972 94 1009. 230 K. W. Browall T. Bursh L. V. Interrante and J. S. Kasper Znorg. Chem. 1972 1 1 , 2 3 1 W. P. Fehlhammer and L. F. Dahl J. Amer. Chern. SOC. 1972,94 3377. 232 P. L. Goggin R. J. Goodfellow and F. J. S. Reed J.C.S. Dalton 1972 1298. 233 W.J. Cherwinski H. C. Clark and L. E. Mayer Znorg. Chem. 1972 1 1 1511. 2 3 4 J. H. Price A. N. Williamson R. F. Schram and B. B. Wayland Inorg. Chem. 1972, 235 G. W. Bushnell K. R. Dixon R. G. Hunter and J. T. McFarland Canad. J. Chem., 236 237 J . A. Evans M. J. Hacker R. D. W. Kemmitt D . R. Russell and J. Stocks J.C.S. 238 W. Urland and R. Hoppe Z . anorg. Chem. 1972 392 23. 2 3 9 S. S. Batsanov P. N. Kusnetsov and E. D. Ruchkin Russ. J. Inorg. Chem. 1972 17, 240 G. A. Ozin M. Moskovits P. Kiindig and H. Huber Canad. J . Chem. 1972,50,2385. 2 4 1 T. W. Thomas Chehsiung Hsu M. M. Labes P. S. Gomm A. E. Underhill and 1800. 11 1280. 1972 50 3694. M. W. Adlard and G. Socrates J.C.S. Dalton 1972 797. Chem. Comm. 1972 72. 168. D. M. Watkins J.C.S. Dalton 1972 2050 The Transition Elements 31 1 complex.242 K1.64Pt(o~)2 ,xH20 is suggested as a new solid-state proton battery2, and the nature of the oxidation-reduction reaction in this and related complexes has been Two reports question the present belief that PtC1 is tetrahedral.In a footnote on a study of organometallic platinum complexes spectroscopic and other evidence is summarized.245 A powder X-ray study suggests that it is in fact six-co-ordinate with a similar structure to PtBr and PtI .246 In K,Pd(SCN),, the Pd is in approximately square-planar co-ordination with two different Pd-S bond lengths and with infinite metal chains in the Two different syntheses of C1F,+PtF6- have been reported. The main interest is in the stabil-ization of the chloronium ion with chlorine formally Clv".248 In flash photolysis studies of the photochemical aquation of Na2PtC1, a similar intermediate to that found for the analogous bromide and chloride salts [PtCl,OHl2- is identi-fied but the new species [Pt"'Cl,]- is also found confirming the belief that a Pt"' species is also involved in the hydrolysis mechanism.249 11 The Copper Group Copper.-H,BCN- forms copper complexes of the type (Ph,P),Cu'NCBR, containing metal-nitrogen bonds.The dimeric complex [(Ph3P)2Cu(NCBH3)]2 was shown to have the structure (24) in both solid and solution.2s0 The conden-sation product of pyridine-2-carbaldehyde and 2-aminobenzothiazole (25) has been used as a ligand to produce a Cu" complex. An X-ray analysis indicates that it contains the biL (26) and a biL picolinic ion.The picolinic acid may be derived from hydrolysis of the ligand followed by oxidation of the pyridine-2-carbalde-hyde product at the expense of the ligand itself.251 2 4 2 L. V. Interrante J.C.S. Chem. Comm. 1972 302. 2 4 3 F. N . Lecrone and J. H. Perlstein J.C.S. Chem. Comm. 1972 75. 244 P. S. Gomm A. E. Underhill and D . M. Watkins J.C.S. Dalton 1972 2309. 2 4 s P. M. Cook L. F. Dahl and D. W. Dickerhoof J . Amer. Chem. SOC. 1972,94 5511. 2 4 6 2 4 7 A. H. Mawby and G. E. Pringle J. Inorg. Nuclear Chem. 1972,34 2213. 248 ( a ) F. Q. Roberto Znorg. Nuclear Chem. Letters 1972 8 737; (6) K. 0. Christe ibid., 249 R. C. Wright and G. S. Lawrence J.C.S. Chem. Comm. 1972 132. 2 5 0 S. J. Lippard and R. S. Welcher Znorg. Chem. 1972 1 1 6 . 2 5 1 A.Mangia M. Nardelli C. Pellizzi and G. Pellizzi J.C.S. Dalton 1972 996 2483. M. F. Pilbrow J.C.S. Chem. Comm. 1972 270. 1972 8 741 312 W. E. Smith and J. M . Winjield H A novel form of macrocycle (27) formed from two 1,lO-phen groups bridged by NH has been synthesized and the copper complex (28) prepared.252 H Histidyl groups are important as metal-binding sites in proteins. The crystal structure of the compound produced from the reaction of Cu" with the smallest peptide containing a histidyl group shows that it is basically a Cu" double oxygen-bridged dimer with six dimeric units forming a three-dimensional unit enclosing disordered water. A small-angle X-ray scattering study demonstrates that a similar species is present in solution.' Ammoniacal solutions containing Cu" ions oxalodihydrazide and acetaldehyde give a deep-blue solution on oxygena-tion.The solution is used in copper analysis and has been widely upheld as a copper-oxygen complex and a model for oxygen carriers in Cu protein complexes. The X-ray structure of the isolated product shows that it is not an oxygen complex, but that the ligands have undergone an extensive interligand condensation. The copper is co-ordinated to four nitrogens with an axial water ligand. Oxygen is involved in the condensation reaction. 54 A number of points of interest have appeared from the many X-ray crystal structure papers on copper compounds. The sulphur-bridged trimer, [Cu(Me,PS)Cl] has two copper atoms bridged through the sulphur of one ligand with an adjacent terminal chlorine whereas normally the chloride would be expected to be the bridging ligand.Presumably the larger bond angle in the trimer compared with the more widely studied dimer allows the sulphur to be more easily accommodated.255 2 5 2 S. Ogawa T. Yamaguchi and N. Gotoh J.C.S. Chem. Comm. 1972 571. 2s3 R. Osterberg B. Sjoberg and R. Soderquist J.C.S. Chem. Comm. 1972 983. 2 5 4 G. R. Clark B. W. Skelton and T. N. Waters J.C.S. Chem. Comm. 1972 1163. 2 5 5 J. A. Tethof J. K. Stalick P. W. R . Corfield and D. W. Meek J.C.S. Chem. Comm., 1972 1141 The Transition Elements 313 Dinitratobis-a-picolinecopper(r1) exists in two forms both of which belong to the same space group and have similar unit cells but quite different crystal-packing arrangements.,' The structures of Cu(NC,H,OMe),X (X = C1 or Br) were expected to be quite different from i.r.results but in fact have proved to be very similar.257 Anhydrous Na,Cu(CO,) consists of infinite sheets of Cu atoms bridged by carbonates through two of the oxygens the third CO distance is shorter than those involved in bridging.258 An assessment of antiferromagnetism in dinuclear Cu" carboxylate complexes has appeared. 140 compounds were considered some were rejected systematic trends were established among the rest using a singlet-triplet-singlet The mechanism of superexchange in Cu" dimers with bridging N-oxide groups has been discussed and the thermal population of excited states other than those predicted by the vector model is proposed.260 A summary of the magnetic data on a number of copper dimers and the evidence for spin-spin interaction have been discussed.261 The 4.2-300 K magnetic susceptibility of CuS has been reported and explained on the basis of a trimer of copper(rr) atoms.262 Magnetic susceptibilities for the tetrameric complexes cu4Ox& (x = c1 L = Ph,PO; X = Br L = Ph,PO or C,H,N) have been measured between 1.2 and 294K, and in each case a maximum susceptibility is found in the 40-60 K region.The results are significantly different from the related anion [CU,OC~,,]~- and it is suggested that the ground state of each ion is non-degenerate whereas for the neutral complex it is doubly degenerate. The theory for tetramers is developed using a spin-pair Hamiltonian for the doubly degenerate case and excellent agreement between theory and experiment is obtained.263 The triL N-2-pyridylsalicylaldimine7 gives rise to a tetranuclear Cu" cluster with two pairs of copper atoms bridged by a double oxygen bridge lying one above the other so that the coppers form a square.There is little interaction between the pairs of copper atoms.264 The relationship between structure and pressure-dependent magnetic susceptibility data has been studied. The sus-ceptibility is sensitive to bond-angle changes.265 The magnetic properties of hydroxo-bridged bipy complexes266 and Cu" quinoxaline complexes bridged either by chlorines or by the quinoxaline group have been The magnetic susceptibility from 4.2-300 K of Cu(NH,),CO indicates that it is an 2 5 6 A. F. Cameron D. W. Taylor and R. H. Nuttall J.C.S.Dalton 1972 5 8 . 2 5 7 P. Singh D. Y. Jeto W. E. Hatfield and D. J. Hodson Znorg. Chem. 1972 11 1657. 2 5 8 P. C. Healy and A. H. White J.C.S. Dalton 1972 1913. 2 5 9 R. W. Jotham S. F. A. Kettle and J. A. Marks J.C.S. Dalton 1972 428. 2 6 0 2 6 1 '" B. N. Figgis and D. J. Morton J.C.S. Dalton 1972 21 7. 263 M. E. Lines A. P. Ginsberg R. L. Martin and R. C. Sherwood J . Chem. Phys. 1972, 2h4 J . Drummond and J. S. Wood J.C.S. Dalton 1972 365. 2 6 5 2 6 6 J . A. Barnes D. J. Hodson and W. E. Hatfield Znorg. Chem. 1972 11 144. 2 6 7 C. V. Inman J. A. Barnes and W. E. Hatfield Znorg. Chem. 1972 11 765. R. W. Jotham S. F. A. Kettle and J. A. Marks J.C.S. Dalton 1972 1133. W. E. Hatfield Znorg. Chem. 1972 11,217. 57 1 . E. Sinn and W. T. Robinson J.C.S.Chem. Comm. 1972 359 3 14 W. E. Smith and J. M. Winfield antiferromagnet with a weak ferromagnetic interaction probably caused by slightly canted spins between magnetic sublattices.268 E.p.r. magnetic anisotropy and electronic spectral data on an eight-co-ordinate Cu" complex are in agreement with crystal-field theory.268 Complexes of the type Cu(Et,en),X (X = C104 BF, or NO3) are thermochr~mic.~~~ Physical properties indicate that there is a temperature-dependent interaction between the anion and the CuN plane giving a more square-planar geometry at low temperatures. Cu" benzoate dimers have been studied by n.m.r. The delocalization of electrons into the ligands is consistent with an exchange mechanism.271 Silver and Gold.-Compounds of AuV have been reported for the first time.[Xe,F J+[AuF,]- can be prepared by a direct reaction of XeF F, and AuF ; fluorination of CsAuF gives CSAUF, and fluorination with oxygen of CsAuF, gives O,+[AuF,]-. The CsAuF salt is isomorphous with other noble metal CSMF salts and Raman spectra are rather similar to those for AuF,-Well-defined compounds of formula MAu(NO,) (M = Na K Rb or Cs) were prepared by reaction with N" and NV oxide systems. All the nitrates are uni-dentate and square planar the first examples of solely unidentate NO3- in this type of compound.273 Although gold is inert to fluorosulphuric acid it has now been shown to react with bromine(1) fluorosulphate to form the complex Au(SO,F),(BrSO,F) . 274 The first ligand-induced disproportionation of Ag' in solution is reported.275 The addition of KOH-MeOH followed by C6H1 ,NC, to a Ph,PAuI suspension in methanol produces the novel complex (29).276 I -\A,.,Au N=C Tetrameric complexes of formula [(Me,P)AgCl] have been prepared and the new Si-0-Ag linkage is obtained from reactions of it and related complexes, with NaOSiMe,. A similar linkage has also been found for Cu and Au.277 2 6 8 D . Y. Jeter D. J. Hodson and W. E. Hatfield Inorg. Chem. 1972 11 185. 2 6 9 C. D. Garner P. Larnpert F. E. Mabbs and J. K. Porter J.C.S. Dalron 1972 320. * l o A. B. P. Lever E. Mantovani and J. C. Donini Inorg. Chem. 1971 10 2424. 2 7 2 7 2 K. Leary and N. Bartlett J.C.S. Chem. Comm. 1972,903. 2 7 3 C . C. Addison G. S. Brownlee and N. Logan J.C.S. Dalton 1972 1440. 2 7 4 W. M. Johnson R.Dev and G. H. Cady Inorg. Chem. 1972,11,2260. 2 7 5 M. A. Kestner and A. L. Allred J. Amer. Chem. SOC. 1972,94 7189. 2 7 6 G. Minghetti and F. Bonati Angew Chem. Internat. Edn. 1972 11 429. 2 7 7 H. Schrnidbaur J. Adhofer and K. Schwirten Chem. Ber. 1972 105 3382. P. A. Zelonka and M. C. Baird Inorg. Chem. 1972 11 134 The Transition Elements 315 A series of gold cluster compounds of the type Au,L8X3 has been prepared.278 The first crystal structure of one of these was reported last year. The structure of the first of a new type of cluster compound [AuP(tol),],[BPh,], shows that the Au atoms are arranged at the points of an ~ctahedron.,~' The bonding pattern of the compounds is considered and a rationalization proposed. The crystal structure of (Au(Pr'O),PS,) shows that although the molecule is dimeric a one-dimensional gold chain with each dimer linked by a slightly longer Au- Au distance is formed.280 The electronic spectrum of tetragonally distorted Ag" in the compounds MNAg"F (MIv = Sn Pb Zr or Hf) has been reported28' and other fluorides of the same type (MIv = Ti Ge Pb Pd or Pt) have been prepared.Some of them (MIv = Sn Pb; or Pd) have magnetic pro-perties which obey the Curie-Weiss law but for others (MIv = Zr or Hf) there is evidence of exchange occurring. The deep-blue colour of the latter two is further evidence of this. 82 12 The Zinc Group A range of selenourea complexes of Zn" Cd" Hg" and Co" have been synthesized. The donor properties of selenourea are similar to those of thiourea. The i.r. M-L stretching frequencies lie in the range 245-167 cm- ' about 20 % lower in frequency than equivalent thiourea complexes.283 A series of Zn" and Cd" complexes containing hydrazine has been reported.Cadmium complexes of the types [CdBr,(N,H4),],4H20 and [Cd(H20),(N2H4),]S04 have both been established.284 The complex Hg" cations [HgXL]+ [HgL2I2+ (L = PMe or AsMe,) [HgMepy]' and [MeHgSMe,]' have been synthesized as NO3- and BF4- salts and characterized by i.r. Raman and 'H n.m.r. spectra.28' The metal clathrates Cd(en),M(CN) ,2C,H,(M = Cd or Hg) have M ions in tetrahedral co-ordination.286 The U.V. spectra of Zn" Cd" and Hg" tetrahalides have been assigned to the t -P a transition with no evidence of transitions from t or e non-bonding The first direct observation of a polarized sharp-line porphyrin absorption spectra is reported at 77 K for zinc porphyrin doped into a triphenyl-ene crystal.* The thermodynamics of decomposition of mercury(1x) halide dioxan complexes have been re-examined. Previous thermodynamic data gave 2 7 8 F. Cariati and L. Naldini J.C.S. Dalron 1972 2286. 279 P. L. Bellon M. Manassero L. Naldini and M. Sansoni J.C.S. Chem. Cornm. 1972, 1035. S . L. Lawton W. J. Rohrbaugh and G. T. Kohotailo Inorg. Chem. 1972 11 2227. 2 8 ' G. C. Allen R. F. McMeeking R. Hoppe and B. Miiller J.C.S. Chern. Cornm. 1972, 291. B. Muller and R. Hoppe Z . anorg. Chem. 1972 392 37. 44 573. 647. 283 G. B. Aitken J. L. Duncan and G. P. McQuillan J.C.S. Dalton 1972,2103. 284 R. Y. Aliev N . N. Guseinov and N . G. Klyuchnikov Russ.J. Inorg. Chem. 1972 17, 2 8 5 P. L. Goggin R. J. Goodfellow S. R. Haddock and J. G. Eary J.C.S. Dalton 1972, 2 8 6 T. Iwamoto and F. Shriver Inorg. Chem. 1972 11 2570. 28' P. Day and R. H. Seal J.C.S. Dalton 1972 2054. 2 8 8 B. F. Kim J. Bohandy and C. K. Jen J. Chem. Phys. 1972 57 1792 316 W. E. Smith and J. M. WinjieId the bond order Br > I > C1 in contrast to the spectroscopic order C1 > Br > I. The new data are in agreement with the spectroscopic result.289 A structural investigation of the mode of bonding of Cd" and Hg" urea deriva-tives has begun. At present it is common practice to assume that they are oxygen-bonded if a shift in carbonyl frequency occurs on complexation. The crystal structure of hexakis-(2-imidazolidinone) Cd" perchlorate demonstrates that it is oxygen-bonded but no corresponding i.r.shift is found. Bis-(2-imidazolidinone)-Hg"C12 shows such a shift but it is a polymer with two oxygen and two nitrogen bonds to each mercury.290 [(Et,O),Cd(B,,H,,),] has been shown by an X-ray structural analysis to consist of two bridging B,,H, groups each bonded to the cadmium ions by two three-centre bonds with two other groups completing the co-~rdination.~" The existence of the ion [Cd2I6l2- has been confirmed by a structural determination on a [Cd,LI,] complex L = tris-(2-dimethylamino-ethy1)amine. The anion consists of two CdI tetrahedra linked by a common edge. The cations are five-co-ordinate Cd" complex ions.292 The first example of a linear chain polydentate complex with helical co-ordination is reported for a 1 1 complex.The ligand has 3N and 2s co-ordination and all are shown to be at bonding distances. There is only one molecule per unit cell and the crystal is optically active. 293 In spite of the wide use of zinc dithizonate in analytical chemistry no crystal structure has appeared until this year. The zinc is tetrahedrally co-ordinated to both S and N. The methyl derivative would be expected to be tetrahedral for Nil' but to be distorted for Zn" in agreement with the known stabilities.294 Mercury dehydrodithizone is a sulphur-bridged polymer with five-co-ordinate Hg.29s ZnSO ,2H,O crystals contain both octahedral and tetrahedral Zn'1,296 Hg3(A1Cl,) contains Hg,,' units of a type discussed last year297 and in Zn(OAc) ,2H20 the Zn" is co-ordinated to seven oxygen^.,^^ 13 Ligands Dithiophosphinic acids have been shown to form insoluble polymeric complexes with CO" and Ni".The co-ordination sphere of the metal can be expanded by the addition of base and depending on the nature of the acid selective absorbants for a series of amines have been prepared.299 Cyclic oxamides can isomerize as shown (30) and co-ordinate with Ni" giving product (31) in air and (32) in the 2 8 9 J. C. Barnes Znorg. Chem. 1972 11 2267. 2 9 0 ( a ) J. N. Brown A. G. Pierce and L. M. Trefonas Znorg. Chem. 1972 11 1830; (b) R. J. Majestic and L. M. Trefonas ibid. p. 1834. N. N. Greenwood J. A. McGinnety and J. D. Owen J.C.S. Dalton 1972 989. 2 9 2 P. L. Orioli and M. Campolini J.C.S. Chem. Comm. 1972 1251. 293 L.F. Lindoy D. H. Busch and V. Goedhen J.C.S. Chem. Comm. 1972 683. 2 9 4 A. H. Mawby and H. M. N. H. Irving J . Znorg. Nuclear Chem. 1972 34 109. 2 9 5 W. J. Kozarek and Q. Fernando J.C.S. Chem. Comm. 1972,605. 2 9 6 H. Quinares and S. Baggio J . Inorg. Nuclear Chem. 1972 34 2153. 297 R. D. Ellison H. A. Levy and K. W. Fung Znorg. Chem. 1972 11 833. 2 9 8 W. Harrison and J. Trotter J.C.S. Dalton 1972 936. 299 W. Kuchen J. Delventhal and H. Keck Agnew Chem. Internat. Edn. 1972 11 435 The Transition Elements 317 absence of air. With Co" and Cu" a product similar to (32) is obtained with or without air.300 A detailed investigation of fused-ring polymeric phthalocyanines prepared from 1,2,4,5-tetra-azabenzene (TCB) or pyromellitic anhydride (PMA) and metal salts showed that the present literature work-up methods lead to impure products.Pure compounds obtained from the reaction of TCB and metal salts were mono-meric with imide or carboxylate functional groups but PMA and metal salts gave polymers with imide not carboxy-groups at the ~eriphery.~" Template synthesis of compounds which represent corrins more faithfully than previous ligands302 and a series of octa-aza-annulenes together with the first metal complex of this type is reported.303 A simple and easy preparation of cyclam (1,4,8,1l-tetra-zizacyclotetradecane) giving a 20% yield,304 and direct methods of preparing related saturated tetra-aza macrocycles have been reported.305 A general mechanism for the incorpor-ation of a metal ion in a porphyrin which rationalizes the variety of kinetic results at present available has been proposed.It appears that a metal ion, proton or N-alkyl group on one side distorts the porphyrin ring and allows attack by a second metal ion on the other side.306 1.r. spectra of tri(bipy) and tri(phen) complexes of Fe"*"' Cu" and Co"*"' have been assigned from isotope studies. There are two distinct series those with t,, orbitals only filled and those with partially filled eg orbitals as well. It appears 300 H. Kanatomi and I . Murase Znorg. Chem. 1972 11 1356. 3 0 1 D. R. Boston and J. C. Bailar Inorg. Chem. 1972 11 1578. 302 D. St. C. Black and A. J. Hartshorn J.C.S. Chem. Comm. 1972 706. j o 3 J. E. Baldwin R. H. Holm R. W. Harper J. Huff S. Koch and T. J . True Inorg. 304 E. K. Barefield Znorg.Chem. 1972 11 2273. 305 A. M. Tait and D. H. Busch Inorg. Nuclear Chem. Letters 1972 8 491. 3 0 6 R. Khosropour and P. Hambright J.C.S. Chem. Comm. 1972 13. Nuclear Chem. Letters 1972 8 393 318 W. E. Smith and J. M . Winfield that significant electron delocalization occurs if antibonding eg orbitals are filled.307 M.c.d. spectra of octaethylporphyrins of Co Cu Ag Zn between room temperature and 8 K have been reported. The metal plays little part in the spectra and is only weakly coupled to the 7c-ring system. Vibronic fine structure is found on only one band.308 The electronic spectra of Zn" Ni" Fe" Mn" Mg" and Al"C1 porphyrins and their reduction products have been studied.309 The advantages of 13C n.m.r. and 'H n.m.r. in determining the stereochemistry of Ph,P and Ph,As complexes have been pointed out.310 A study of metal ring conformation for edta metal complexes shows that only two ring conformations will occur and ten conformational types of the complex are possible.311 3 0 7 Y. Saito J. Takemoto B. Hutchinson and K. Nakamoto Znorg. Chem. 1972,11,2003. 308 R. Gale A. J. McCaffery and M. D. Rowe J.C.S. Dalton 1972 597. 309 D. W. Clack and J. R. Yandle Znorg. Chem. 1972 11 1738. 310 B. E. Mann B. L. Shaw and R. E. Stainbank J.C.S. Chem. Comm. 1972 151. 3 1 1 B. Lee Inorg. Chem. 1972 11 1072

ISSN:0069-3022    

DOI:10.1039/GR9726900277

出版商:RSC    

年代:1972

数据来源: RSC