9 Organometallic Compounds Part (i) The Main Group Elements By D. J. CARDIN M. F. LAPPERT J. D. SMITH and D. R. M. WALTON School of Molecular Sciences University of Sussex Brighton BN 7 9QJ THEliterature of organometallic chemistry grows at an alarming rate. The year 1970 has seen the appearance of a new journal.’ The revision of Ingoid’s classic text provides a useful account2 of the mechanism of electrophilic substitution at saturated carbon with particular reference to the Hg-C bond. Books dealing with organometallic chemistry of the Main Group elements include texts on inorganic ring compo~nds,~ organosilicon heteropolymers and carborane~,~ hetero-compounds,’ organometallic compounds of tin‘ and arsenic antimony and bismuth,’” organometallic reaction^,'^ redistribution reaction^,'^ and spectro- scopic methods in organometallic chemistry.8 A commercial journal continues to provide a detailed review of organometallic literature the latest volume covers (except for Si) the year 1969.’ After an interval of six years two further volumes on progress in boron chemistry have appeared including articles on carb-oranes,”“ polymers containing clusters of boron atoms,”’ use of isotopic (’ ‘B and 2H) labels,”‘ oxidation of organic compounds in the presence of boron ’ ‘Organometallics in Chemical Synthesis’ ed.J. G. Noltes and D. Seyferth Elsevier Amsterdam 1970 vol. 1. C. K. Ingold ‘Structure and Mechanism in Organic Chemistry’ Bell London 2nd edn. 1969 Ch. 8. I. Haiduc ‘The Chemistry of Inorganic Ring Systems’ (2 vols.) Wiley New York 1970.R. N. Grimes ‘Carboranes’ Organometallic Chemistry Series (ed. P. M. Maitlis F. G. A. Stone and R. West) Academic Press New York 1970. S. N. Borisov M. G. Voronkov and E. Ya. Lukevits ’Organosilicon Heteropolymers and Heterocompounds’ Plenum Press New York 1970. ‘ W. P. Neumann ‘The Organic Chemistry of Tin’ Wiley London 1970; R. C. Poller ‘The Chemistry of Organotin Compounds’ Logos Press London 1970. (a)G. 0. Doak and L. D. Freedman ‘Organometallic Compounds of Arsenic Anti- mony and Bismuth’ Wiley London 1970; (6) ‘Organometallic Reactions’ ed. E. I. Becker and M. Tsutsui Wiley-Interscience New York 1970 vol. I Ch. 1 by T. Mole (redistribution reactions of organoaluminium compounds) ; Ch. 3 by L. G. Makarova (reactions of organomercury compounds also Ch.3 of vol. 2); vol. 2 Ch. 1 by K. Moedritzer (the redistribution reaction); (c) J. C. Lockhart ‘Redistribution Reactions’ Academic Press New York 1970. ‘Spectroscopic Methods in Organometallic Chemistry’ ed. W. 0. George Butter- worths London 1970. Organometallic Chem. Rec. (B) 1970 vol. 6. lo (a) R. E. Williams Progr. Boron Chem. 1970 2 37; (6) T. L. Heying ibid. p. 119; (c) J. E. Odom and R. Schaeffer ibici. p. 141. 272 D. J. Cardin M. F. Lappert J. D. Smith and D. R. M. Walton compounds,' lUneighbouring-group effects of boron in organoboron chemistry (see also ref. 12),'lb thermochemistry of boron compounds,'" topics in BN chemistry,' Id and organoboronsulphur compounds. ' le Professor E.G. Rochow has contributed an essay entitled 'Of time and carbon- metal bonds.'13 The following specialist topics have been reviewed :n.m.r. spectra of organometallic ally1 compounds ; a-heterodiazoalkanes and the reactions of diazoalkanes with derivatives of metals and metalloids ;l syntheses of organo- metallic compounds by thermal decarboxylation ;' polyfluoro-aromatic,' perfluorovinyl,' 7b chlorocarbon,'8 and bromocarbon derivatives of metals and metalloids ; sulphur dioxide and trioxide insertion reactions into M-C bonds ;I9 some recent results in carbanion chemistry ;20 the thermodynamics of redistribution reactions ;" fast exchange reactions of Group I 11 and I11 organo-metallic compounds ;22 ~rgano-berylliurn~~" and -magnesium23' compounds ; Group 124n and Group I11 organometallic ~hernistry;~~' metal-boron com-pounds ;25 transition-metal-carborane complexes;26 organothallium chem-istry2'" and the use of thallium in organic synthesis;"' isoelectronic species in the organo-aluminium -phosphorus and -silicon series;'* organosilicon ketones;29 platinum metal catalysis in silicon chemistry ;30 n-bonding3 la and radicals3 ' in silicon and Group IVB organometallic chemistry ; non-bonded interactions in organometallic compounds of Group IVB ;32 19Sn Mossbauer I' (a) W.G. Woods and R. J. Brotherton Progr. Boron Chem. 1970 3 1; (b) D. S. Matteson ibid. p. 117; (c) A. Finch and P. J. Gardner ibid. p. 177; (d) H. Noth ibid. p. 21 1 ; (e) B. M. Mikhailov ibid. p. 313. l2 D. S. Matteson Accounts Chem.Res. 1970 3 186. l3 E. G. Rochow Adti. Organometallic Chem. 1970 9 I. '' L. A. Fedorov. Russ. Chem. Rev. 1970,39 655. l5 M. F. Lappert and J. S. Poland Adc. Organometallic Chem. 1970,9 397 l6 G. B. Deacon Organometallic Chem. Rev. (A) 1970 5 355. I' (a)S. C. Cohen and A. G. Massey Adv. Fluorine Chem. 1970,6,185;(b)I. L. Kunyants, R. N. Sterlin and V. L. Isaev Zhi4r. Vsesoyuz. Khim. obshch. im D.I. Mendeleeva 1970 15 25 (Chem. Abs. 1970,72 132825u.). T. Chivers Organometallic Chem. Rev. (A) 1970 6 1. l9 W. Kitching and C. W. Fong Organometallic Chem. Rev. (A) 1970 5 281. 2o U. Schollkopf Angew. Chem. lilternat. Edn. 1970 9 763. 21 A. G. Lee Organometallic Chem. Rev. (A) 1970 6 139. 22 J. P. Oliver Ado. Organometallic Chem. 1970 8 167. 23 (a) G.E. Coates and G. L. Morgan Adv. Organometallic Chem. 1970 9 195; (b) B. Blagoev and D. Ivanov Izvest. Otdel. Khim. Nauk Bulg. Akad. Nauk 1970 2 629 (Chem. Abs. 1970,73 3956). 24 'Methoden der Organischen Chemie' (Houben-Weyl) Thieme Stuttgart 1970 (a) vol. XIII/I ; (6)vol. XIII/4. 25 G. Schmid Angcw. Chem. Internat. Edn. 1970,9 819. 26 L. J. Todd Adv. Organometallic Chem. 1970 8 87. 27 (a)H. Kurosowa and R. Okawara Organometallic Chem. Rev. (A) 1970 6 65; A. G. Lee Quart Rev. 1970,24,310; (6)E. C. Taylor and A. McKillop Accounts Chem. Res. 1970 3 338; Aldrichimica Acta 1970 3 4. H. Schmidbaur Adu. Organomrtullic~ Chrm. 1970 9 260. l9 N. V. Komarov and V. K. Roman Russ. Chem. Rev. 1970,39 578. 30 P. N. Rylander Engelhard Industries Technical Bulletin 1970 10 130.3L (a) C. J. Attridge Organornetallic Chem. Rev. (A) 1970 5 323; (6) R. A. Jackson Chem. SOC. Special Publ. No. 24 1970 p. 295. 32 C. F. Shaw and A. L. Allred Organometallic Chem. Rev. (A) 1970,5,95. Organometallic Compounds-Part (i) The Main Group Elements 273 spectroscopy in organotin chemistry ;33 vibrational spectra of organo-tin and -lead compounds ;34 heterocyclic compounds of phosphorus arsenic antimony and bismuth ;3 fluoroph~sphines;~~~ phosphines arsines stibines and bis- muthines including those containing Si Ge Sn or Pb ;36 organophosphorus compounds with an active methylene group ;37 comprehensive surveys for 1970 of organophosphorus chemistry38 and organobismuth chemistry ;3 and the use of tetramethylethylenediamine (TMEDA) in organometallic ~hemistry.~' Except for the above section this review is necessarily selective.The approach follows last year's pattern ;only compounds containing metal-carbon bonds are considered and more particularly in the context of those of their reactions in which the M-C bond is either made or broken. Structural data are kept to a minimum but readers are referred to appropriate sections in Volume (A) of Annua! Reports. Because of circumstances beyond our control it was not possible for us to consult December issues for the majority of journals for 1970; for the Soviet literature we largely relied on the English translations which cover only about half of 1970. As in recent years compounds of Li Mg B Si Sn and P have received the greatest attention but there appears to be a new impetus in TI organometallic chemi~try.~' Of some general interest are binuclear organometallic compounds containing a Group IVB element bonded via carbon to a transition metal.These compounds frequently appear to have unusual stability' 1342 and com- pounds may be obtained in which the transition metal is either of unusual co-ordination number [e.g. Ni(CPh,SiMe,),]" or in unusual oxidation state [e.g. Cr(CH2SiMe,)4],42 or in which 7r-acceptor ligands are not required [e.g. TiR4" or CrR442 (R = CH,SiMe,)] ;kinetic stabilities of compounds and the absence of j'l-olefin-elimination pathways appear to be important. In com- pounds such as (7c-C,H5)(OC),MoCH,SiMe3,the C-Si bond is cleaved by nucleophiles under exceptionally mild conditions :43 the transition metal neigh- bouring-group effect may be associated with the thermodynamic stability of the delocalised carbanion (n-C,H,)(OC),MoCH; which may thus be regarded as an anionic metal carbene complex.33 P. J. Smith Organometallic Chem. Rev. (A) 1970 5 373; J. J. Zuckerman Adv. Organometallic Chem. 1970 9,22 34 T. Tanaka Organometallic Chem. Rev. (A) 1970,5 I. '* (a)F. G. Mann in 'The Heterocyclic Derivatives of Phosphorus Arsenic Antimony and Bismuth,' Wiley-Interscience London Second Edn. 1970; (b)J. F. Nixon Adc. Inorg. Chem. Radiochem. 1970 13 364. '' J. E. Drake and C. Riddle Quart. Rev. 1970,24,263; E. W. Abel and S. M. Illingworth Organometullic Chem. Rev. (A) 1970 5 143. 3i A.N. Pudovik and G. E. Yastrebova Run. Gem. Rev. (A),1970 655. 3M 'Organophosphorus Chemistry' ed. S. Trippett (Specialist Periodical Reports) The Chemical Society London 1970 vol. 1. 39 P. G. Harrison Organometallic Chem. Rev. (A) 1970 5 183. " C. Agami Bull. Snc. chim. France 1970 1619. " M. R. Collier M. F. Lappert and M. M. Truelock J. Organometallic Chern. 1970 25 C3. 42 G. Yagupsky W. Mowat A. Shortland and G. Wilkinson Chem. Comm. 1970 1369. '' M. R. Collier B. M. Kingston and M. F. Lappert Chem. Comm. 1970 1498. D. J. Curdin,M. F. Luppert J. D. Smith and D. R. M. Walton Group I.-Lithium. The structure of fluorenyl-lithium (and Na or K analogues) complexes with glymes [MeO(CH,CH,O),Me; 1 < n < 61 in ether solvents has been examined spectros~opically.~~ An equilibrium exists between contact and glyme-separated ion pairs which is dependent on n and temperature.Solutions of Bu"Li and 1,3-diphenylbut-l-enyl-lithiumshow associated complexes (Bu"Li),- (DPBLi), also existing in tight and solvent-separated forms but no values of n or were determir~ed.~' An ionic structure [Cl,C=C=CCl]-Li+ is proposed for the new trichloroallenyl-lithium which is stable below -90 0C.46 The unusual stability of tris(trimethylsi1y)methyl-lithium prepared inter ulia by MeLi metallation of (Me,Si),CH in THF-Et,O may be associated with delocalisation of carbanion change into Si d-orbital~.~' The first triarylsilylmethyl metal reagents (-Li and -MgX derivatives) have been prepared; they are best made by Bu"Li metallation of corresponding bromides.48 Metallation with alkyl- lithiums continues to be widely studied.Ethyl acetate is metallated by LiN- (SiMe,) at -78 "C; the lithio-derivative is more stable than previously reported and is useful for preparing P-hydroxy-esters from aldehydes and ketones.49 Allene can be poly-lithiated at -50 "C in THF-hexane the products reacting with Me3SiC1 to give silylated derivative^.^' An a-elimination of LiCl is postu- lated following lithiation of 2-chloronorbornene ; the reaction involves a new type of ring contraction (Scheme l)?' Transmetallations with organolithium Scheme 1 compounds have afforded LiC(=N,)CO,Et (from the bis-mercury compo~nd),~~ which couples normally with e.g. Me3SiC1 or Bu",SnCl affording a-heterodi- azoalkanes; and have afforded Me,NCH,Li (from the SnBun3 c~mpound),'~ using Bu"Li,TMEDA.The TMEDA complex is both more reactive and more selective (than uncomplexed BuLi) in side-chain metallation of o-Me-C,H,-NMe ,s4 although benzyl- and 2- and 4-pyridylmethyl-lithium have been '' Lock Lim Chan K. H. Wong and J. Smid J. Amer. Chem. SOC.,1970 92 1955. 45 J. W. Burley and R. N. Young Chem. Comm. 1970,991. " G. Kobrich and E. Wagner Chem. Ber. 1970 103 2515. 47 M. A. Cook C. Eaborn A. E. Jukes and D. R. M. Walton J. Organornetallic Chem. 1970 24,529. '' A. G. Brook J. M. Duff and D. G. Anderson Canad. J. Chem. 1970,48 561. " M. W. Rathke J. Amer. Chem. SOC.,1970,92 3222. F. Jaffe J. Organometallic Chem. 1970 23 53. " P. G. Gassman and T.J. Atkins J. Amer. Chern. SOC.,1970,92 5810. 52 U. Schollkopf and H. Frasnelli Angew. Chem. Internat. Edn. 1970 9 301. 53 D. J. Peterson J. Organometallic Chem. 1970 21 P63. 54 R. E. Ludt G. P. Crowther and C. R. Hauser J. Org. Chem. 1970 35 1288. Organometallic Compounds-Part (i) The Main Group Elements prepared free of ring substitution using Bu"L~.~~ Many nitroaryl-lithiums have been prepared by metallation.56 A method of obtaining pK values (within a standard deviation of 3.57) of weak carbon acids X-CH,-Y by comparing the 'H n.m.r. shifts of the species X-CH,-Y and X-CHLi-Y has been devised." The formation of carbenes from CC1,Li has been demonstrated by dichlorocyclopropane formation with c5<8 alkenes.s8 Other reactions involv-ing unstable intermediates include the synthesis of two stereoisomers of (1) from (11 MeLi and 6,6-dibromobicyclo[3,l ,O]hexane probably via cyclohexa-1,2-diene;' the preparation of ditolyls from p-tolyl-lithium and p,p'-ditolyl sulphoxide which is shown to involve arynes;59band the reaction of cis-and trans-2-lithio-2-butenes neopentyl-and neophyl-lithium with cobalt(r1) chloride to afford the dimeric organic species with complete retention of stereochemistry and without rearrangement (respectively)uia organo-cobalt intermediates.60 The reaction of ketones with alkyl halides and lithium may proceed via organolithium reagents and provides a one-step synthesis of tertiary alcohols with yields generally better than the two-stage Grignard procedure.6 Treatment of 2-azo-allyl-lithium compounds with unsaturated hydrocarbons susceptible to nucleophilic attack gives heterocycles e.g.,(2),constituting the first example of an anionic [n4+ 7c2] Li+ Phz-C\.N ,;/ -CH + trans-stilbene -+ H Ph Ph 'h -.cycloaddition.62 Thermolysis of o-nitrophenyl-lithium yields no benzene but a dimeric species which can be converted to (O-N02*C6H&.63 An anion-radical 55 C. G. Sereltas J. F. Estham and C. W. Kamienski Chimia (Swifz.),1970 24 109. 56 P. BuckandG. Kobrich Chem. Ber. 1970 103 1412 1420. 57 D. J. Schaeffer Chem. Comm. 1970 1043. 58 G. Kobrich H. Biither and E. Wagner Angew. Chem. Internat. Edn. 1970 9,169. '' (a) W. R. Moore and W. R. Moser J. Amer. Chem. SOC.,1970 92 5469; (b) K. K. Andersen S.A. Yeager and N. B. Peynircioghi Tetrahedron Letters 1970 2485. '' D. B. Denney and W. R. Davis J. Orgcmometallic Chem.. 1970,24 537. '' P. J. Pearce D. H. Richards and N. F. Scelly Chem. Comm. 1970 1160. 62 T. Kauffman H. Berg and E. Koppelmann Angew. Chem. Internat. Edn. 1970 9 380. 63 P. Buck R. Gleiter and G. Kobrich Chem. Ber. 1970 103 1431. D. J. Curdin M. F. Luppert J. D.Smith and D. R. M. Wulton mechanism is postulated. Comparison has been made between polyhalogenoaryl- lithium reagents and polyhalogenoaryl Grignard reagents in their reactions with Me SiC1-benzophenone mixture^.^^ Both organometallics reacted preferentially with Me,SiCl in tetrahydrofuran (except PhMgBr) the reverse being true in ether. With 1,2-epoxybutane Grignards afforded mainly halohydrins whereas alkyl-lithiums (like dialkylmagnesium compounds) gave high yields of the secondary alcohols (product of nucleophilic ring-opening).6 Sodium and the Heavier Alkali-Metals.Crystals of ethylsodium66 and methyl- pota~sium"~ have been obtained from (i) the appropriate R,Hg and either Na or Na-K and (ii) the appropriate RLi and MOBu'. The sodium compound is rhombohedral in which Na+ ions are in trigonal-pyramidal assemblies. Methyl- potassium is the first methyl-metal derivative with isolated Me- ions in the lattice ; MeK has a hexagonal NiAs structure with each Me group co-ordinated by 6K' ions in a trigonal prismatic arrangement. The solvent(Et,O)-separated but not the contact ion pairs M+[PhCH :CHCH(Ph).Me]- fluoresce in certain ethers at low temperature.68 The complex MeSOCH,Na,THF (from DMSO + NaH in THF) is relatively stable decomposing at 120-1 34 0C.69 Trimesitylborane (TMB) was found to be a suitable non-polar aprotic medium for dissolving alkali- metal reductions ;''this allows for the possibility of a much wider range of reaction conditions than had been possible with (Me,N),PO.Group II.-Beryllium. The mass spectra of R,Be (R = Me Et Pr" Pr' Bu' or But) mostly show ions from associated electron-deficient species only at low source temperatures as expected for such weakly-bridged molecules.' lo A bond dissociation energy D(RBe-R)+ -45 kcal mol- ',was obtained from ionisation potential measurements and the unambiguous identification of (Et,Be,)+ and (Et,Be,H)+ provided conclusive evidence for the trimeric ethyl compound Et,Be,.Alkali-metal dialkylberyllium hydrides NaR,BeH (R = Pr Pr' or Bu') and related species have been described; the molecules are associated by h~drogen-bridging.~~~ Pyrolysis (R = Pr' or Bu') affords olefin some R,Be and a residue of sodium beryllium hydrides the composition of which depends upon the pyrolysis conditions. 1.r. studies show that MeBeBH consists of a mixture of monomers and dimers with structures (3) and (4) having linear (3) (4) " R. C. Edmonson A. E. Jukes and H. Gilman J. Organornetallic Chem. 1970,25,273. 65 R. W. Herr and C. R. Johnson J. Amer. Chem. Soc. 1970 92 4979. 66 E. Weiss and G. Sauermann J. Organometallic Chem. 1970 21 1. 67 E. Weiss and G.Sauermann Chem. Ber. 1970 103 265. J. W. Burley and R. N. Young Chem. Comm. 1970 1649. 6q K. R. Martin J. Organometallic Chem. 1970 24 7. 7o S. D. Darling 0.N. Devgan and R. E. Cosgrove J. Amer. Chem. Soc. 1970,92 696. '' (a)D. B. Chambers G. E. Coates and F. Glockling J. Chem. Soc. (A) 1970 741 ;(b) G. E. Coates and R. E. Pendlebury ibid.,p. 156. Organometallic Compounds-Part (i) The Main Group Elements 277 B-Be-(C) skeleton^.^^" The related Be(BH,) is said to have overall CZ0 H /\ symmetry with an equilateral BeB triangle and Be B bridging atoms lying \/ H out of the plane.72b Magnesium. 1.r. and H n.m.r. studies show that the (cryoscopically) monomeric product (5) from EtMgBr and isopropyl mesityl ketone contains three-co- ordinate magnesium.73 Me OMgX,OEt Me Geminal dimagnesium compounds have been reported CH,(MgX) ,which are converted into alkenes in a Wittig-like reaction with ketones.They exhibit no carbenoid Di-Grignards BrMg(CH,),MgBr prepared in THF have been converted by HMPT in dioxan into magnesiacycloalkanes and their reactions have been An interesting development is the preparation of alkyl- and aryl-magnesium fluorides either from RF and Mg using a cataly~t,~” or using dkalkyl- or diaryl-magnesiums and either BF3,OEt, or Et2A1F.756 Stable hydride complexes e.g.KH,2MgPh2 and KMgBu”,H from R,Mg +KH are reported for the first time although Be and Zn analogues are well known.7sc The compound KMgBus2H reacts with hydrogen at 3000 p.s.i. and pyrolyses to give KMgH ;75d reduction by LiAlH4 of dimethylmagnesium affords MgH as the only magnesium-containing product.75‘ The autoxidation of hex-5-enylmagnesium bromide produces 25 %of cyclo- pentylmethanol in the product suggesting the intermediacy of the 5-cyclohexenyl radical; a radical chain process appears to be operating here rather than the usual two-stage ~xidation.~~ Radicals are also produced in the reaction of PhMg- Br with quinones (the e.s.r.spectra of semiquinones from acenaphthenequinone ’’(a) T. H. Cook and G. L. Morgan J. Amer. Chem. SOC. 1970 92 6487; (b) ibid. p. 6493. ”A. G. Pinkus An Bang Wu and J. G. Lindberg Chern. Comm. 1970 859. ’4 (a) F. Bertini P. Graselli G.Zubiani and G. Cainelli Tetrahedron 1970,26 1281 ;(b) B.Denise J. F. Fauvarque and J. Ducom Tetrahedron Letters 1970 335. ’(a)E. C. Ashby S. H. Yu and R. G. Beach J. Amer. Chem. SOC.,1970,92,433; (b)E. C. Ashby and J. A. Lackashi J. Organometallic Chem. 1970 24 C17; (c) E. C. Ashby and R. C. Arnott J. Organometallic Chem. 1970,21 P29; (d)E. C. Ashby R. A. Kovar and R. C. Arnott J. Amer. Chem. SOC. 1970,92,2182;(e)E. C. Ashby and R. G. Beach Inorg. Chem. 1970 9 2300. 7b C. Walling and A. Cioffari J. Amer. Chem. SOC. 1970 92 6609. D.J. Curdin M. F. Luppert J. D. Smith and D. R. M. Wulton and phenanthraquinone having been observed77") and in the reaction of Grignard reagents with conjugated EtMgBr reacts with various polyarenes (A) forming radical anions and carbanions :tetracene affords A-(identified by e.s.r.) and other species e.g.AH-; perylene gives A- A,- and AH,,- whereas naphthalene does not react presumably because its electron affinity is too low. (cJ reaction with sodium). 78 Grignard reactions of the non-enolizable p-hydrogen-free benzophenone have been further examined. Pinacol formation has been eliminated by use of 'super-pure' magnesium but the reaction still does not follow first-order and the production of benzhydrol even in highly purified systems represents a new complication in this system.79b An improved preparation of Bu",Mg,TMEDA utilises the equilibrium below; the product is obtained by distillation as an air- and moisture-sensitive liquid.80 2(RMgX,TMEDA)fR,Mg,TMEDA + MgX ,TMEDA The addition of LiC104 (1.5 mol) to Grignard reagents is reported to increase the yield of addition products with ketones at the expense of reduction from 36% to as much as 70% in one case.81 Reduction at a metal centre Ti" in alkylation with organomagnesium compounds has been prevented by using R,Mg or its pyridine complex in place of RMgX;82 but alkylation of a large number of transition-metal chlorides has been achieved using MeMgI.83 A novel ring contraction of 3-cyclohexenyI-Grignard compounds (compare e.g.homoallylic Grignards which yield cyclopropyl derivatives) involves the inter- mediate bicyclo[3,1 Olhexane species (6) which however could not be detected by n.m.r. spectros~opy.~~ Allylmagnesium halides (in which a rapid exchange of carbons bonded to magnesium is implied by the 'H n.m.r.spectrum) in contrast to methyl ethyl or phenyl Grignard reagents add to l-alkene~.~~ Evidence for RMgBr (R = 9-trypticyl) has been obtained by incorporation of deuterium by treatment of the product from 9-bromotrypticene and magnesium in the presence of 1,2-dibromoethane with heavy water.86 77 (a)C. Blomberg H. H. Grootveld T. H. Gerner and F. Bickelhaupt J. Orgunomerallic Chem. 1970 24 549; (6) J. J. Eisch and R. L. Harrell ihid. 1970 21,21. 78 F. J. Reinders and R. Prins J. Organometallic Chem. 1970 25 C41. 79 (a) E. C. Ashby F. W. Walker and H. M. Neumann Chem. Comm. 1970 330; (b) S. E. Rudolph and S. G. Smith ibid. p. 1428. M. H. Gitlitz and W. J. Considine J. Organometallic Chem. 1970 23 291. " M. Chastrette and R.Amouroux Chem. Comm. 1970,470. 82 G. J. Dubsky K. S. Boustany and A. Jacot-Guillarmod Chimia (Switz.) 1970,24 17. 83 J. R. C. Light and H. H. Zeiss J. Organometallic Chem. 1970 21 517. 84 A. Maercker and R. Geuss Angew. Chem. Internat. Edn. 1970,9 909. 8s H. Lehmkuhl and D. Reinehr J. Organometallic Chem. 1970 25 C47. 86 C. Agami M. Chauvin and J. Levisalles Bull. Soc. chim. France 1970 2712. Organometullic Compounds-Part (ij The Muin Group Elements Zinc and Cadmium. The nature of the Reformatsky reagent from methyl 2-bromo- 3,3-diphenylpropanoate has been studied and products compared with those from the 1,4-addition product of PhMgBr and methyl inna am ate.^^ The results strongly suggest reactive species with the bromozinc enolate structure (7) and the /OR I \c=c,OZnBr -c-c /\ II'OZnBr OR (7) unsymmetrical p-lactone structure (8).Long-chain organozinc halides (R 'CHR2-Znl and R'CHR2ZnBr) have been prepared by the action of R'MgX (R' = octyl Ph or aralkyl) on ICHR2ZnI (R2 =H or Me).88 Dialkyl- and diaryl-zinc hydride complexes have been further in~estigated.~' MHZnR +ZnR S MH(ZnR,) (M =Li or Na) The equilibrium has been demonstrated by n.m.r. for the alkylzinc derivatives ; the hydride resonance is observed at the surprisingly low field value of -7 p.p.m. from TMS. The existence of intermediate a-halogenobenzylzinc halides (PhCHC 1ZnC1) from phenyldiazomethane and zinc chloride has been demon- strated in THF ;the carbenoid (PhcH) which is generated both dimerizes and inserts into the s~lvent.'~ The reaction of RMgX with CdX,(X =C1 Br or I) in molar ratios of 1 :1 and 2 :1 has been studied ;R,Cd is produced in both cases and is co-ordinated with both CdX and MgX via single or double X bridges from the equimolar mixture; the 2 :1 product affords only R,Cd and MgX, which interact.' 'Divinylmercury reacts with dimethylcadmium to give divinyl- cadmium and methylvinylcadmium.Vinyl groups exchange rapidly on an n.m.r. time-scale when bound to cadmium (no '"Cd or 'I3Cd coupling observed) but methyl groups exhibit show exchange." The reaction of carbonyl compounds with organocadmium reagents has been studied :solvent effects are rep~rted,'~' and the rde of metal halides which initiate reaction by virtue of their Lewis acid character,93b the effect of different modes of preparation and the relative re- activities of R,Cd and RCdX93' and reactions with acid chlorides have also been examined.93d Intermetallic compounds are reported ;for Co Fe Cr Mo and W with both zinc and ~admiurn,'~' for Ge and Zn,"' and for Se with Zn Hg and Mg.94c "W.R. Vaughan and H. P. Knoess J. Org. Chem. 1970,35 2394. T. Chaudron A. Sekerra and P. Rumpf Compt. rend. 1970 270 C 559. 89 G. J. Kubas and D. F. Shriver J. Amer. Chem. SOC.,1970,92 1949. L. Y.Goh and S. H. Goh J. Organometallic Chem. 1970 23 5. "J. R. Sanders and E. C. Ashby J. Organometallic Chem. 1970 25 277. 92 H. D. Visser L. P. Stochilski and J. P. Oliver J. Organometallic Chem. 1970 24 563. 93 (a) F. Huet E. Henry-Basch and P.Freon Bull. SOC.chim. France. 1970,1426;(6)ibid. p. 1415;(c)G. Sousson and P. Freon Compr. rend. 1970,271 C 21 1 ;(d)E. K. Euranto and L. Puuponen Acta Chem. Scand. 1970,24 363. "(a)J. M. Burlitch and A. Ferrari fnorg. Chern. 1970,9 563; (6)N. S. Vyazankin V. T. Bychkov 0.V. Linzina and G. A. Razuvaev J. Organometallic Chem. 1970 21 107; (c) 1. A. Vostokov and B. T. Bychkov Zhur. obshchei Khim. 1970,40,319 (Chem. Abs. 1970,72 121659s). D. J. Cardin M. F. Lappert J. D. Smith and D. R. M. Walton Mercury. Halogenomethylmercury compounds as carbene precursors have again been much studied :95-PhHgCC1,Ph + olefins -cyclopropane derivatives (ref. 95b) Despite the previous production of radicals from organomercurials the e.s.r. spectrum of (Me,Si),C.obtained by photolysis of [(Me,Si),C],Hg is the first reported spectrum of a radical produced by Hg-C bond breaking.96 Reductive demercuration of RHgBr (R = bornyl or neophyl) has been shown to involve free radicals ; it occurs without typical carbonium ion rearrangements extensive D-incorporation using NaBD argues against carbanions and the exolendo ratios with norbornane derivatives parallel those for known radical path- way~.~''.~ Mercuration of cyclobutadienyliron tricarbonyl with Hg(OAc) gives all possible acetoxymercury compounds. The polymercury derivatives are the first of this type with more than two mercury atomsg8 P-Mercuration has been observed for the first time in the reaction of Hg(OAc) in alcohols with crp-unsaturated carbonyl compounds bearing only a-sub~tituents.~~ Methoxy-mercuration of bullvalene and bicyclo[4,2,2]deca-2,4,7,9-tetraene affords the novel species (9) and (lo) respectively.loo The reaction between C[B(OMe),] (9) (10) and Hg(OAc) in ethanol affords the new tetrakis derivative C(HgOAc) ,which is a water-stable crystalline material."' Acetylacetone and related P-diketone complexes of mercury have been examined.The reported Hg(acac) (acacH = acetylacetone) does not appear to exist ;the reaction between HgCl and Na(acac) HgCl Me( 0)C ,OHgCl I MeCO-C-COMe I /c=c\ Me HgCl ClHg 95 (a)D. Seyferth S. S. Washburne C. J. Attridge and Keiji Yamamoto J. Amer. Chem. Soc. 1970,92,4405; (b)D. Seyferth and D. C. Mueller J. Organometallic Chem. 1970 25 293; (c) D.Seyferth and S. P. Hopper ibid. 1970 23 99; (d)D. Seyferth E. M. Hanson B. Prokai and R. J. Cross ibid. 1970 24 33; (e) D. Seyferth and K. V. Darragh J. Org. Chem. 1970,35 1297. 96 A. R. Bassindale A. J. Bowles M. A. Cook C. Eaborn A. Hudson R. A. Jackson and A. E. Jukes,.Chem. Comm. 1970 559. 97 (a) G. M. Whitesides and J. San Fillipo J. Amer. Chem. SOC.,1970,92,6611;(b)V.M. A. Chambers W. R. Jackson and G. W. Young Chem. Comm. 1970 1275. 98 G. Amiet K. Nicholas and R. Pettit Chem. Comm. 1970 161. 99 A. J. Bloodworth and R. J. Bunce Chem. Comm. 1970,753. loo H. P. Loffler and G. Schroder Tetrahedron Letters 1970 21 19. '01 D. S. Matteson R. B. Castle and G. L. Larson J. Amer. Chem. Soc. 1970,92 231. Organometallic Compounds-Part (i) The Main Group Elements 28 1 gives a material of uncertain composition and irreproducible analysis while HacacH,O and Co(acac) or Fe(acac) afford (11) and (12) respectively.'OZn The mercury complex of 2,2,6,6-tetramethylhepta-3,5-dienone has also been re-investigated and the structure (13) in which R = But is now proposed on the basis of n.m.r.data.loZ6 Several improved or convenient syntheses are reported. Anions I- NCS- and S203,-have been used to activate mercury enabling alkylmercury halides to be prepared directly from alkyl iodides and mercury in dry ethan01.l'~ RHgX compounds are converted into R,Hg by treatment with polyethyleneimine the other product HgX being held in solution.' O4 cis-j3-Chlorovinylmercury chloride can be obtained conveniently from the trans-isomer by treatment with benzoyl peroxide ;the desired product can be extracted from the mixture with hexane.'05 The first allenylmercury derivatives CH ,=C=CHHgCl and (CH,=C=CH),Hg were prepared from HgCl and Me,SnCH=C=CH .lo6 Alkylmercury salts have been prepared by decarboxylation of appropriate carboxylic acid ~alts.'~''-~ Perfluoroalkylmercury derivatives R,Hg [R = (CF,),CF or (CF,),C] have been obtained from fluoro-olefins and HgC1 with KF in dimethylformamide.The reaction requires less vigorous conditions than previous preparations and is thought to involve perfluoroalkyl carbanions. O8 The 1 1 adduct of chlorotrifluoroethylene and (Me,Si),Hg Me,SiCF,CFCI- HgSiMe, has been isolated. The insertion into the Hg-Si bond is shown to be stereospecific as is the subsequent elimination reaction.' O9 Methylmercuric Io2 (a) F.Bonati and G. Minghetti J. Organometallic Chem. 1970 22 5; (b) K. Flateau and H. Musso Angew. Chem. Internat. Edn.. 1970 9 379. lU3M. E. Volpin E. A. Tevdoradzi and K. Butin Zhur. obshchei Khim. 1970 40 315. (Chem. Abs. 1970 72 12166m). lo' R. C. Wade and D. Seyferth J. Organometallic Chem. 1970,22,265. lo5 A. N. Nesmeyanov A. E. Borisov and N. V. Novikova Izvest. Akad. Nauk S.S.S.R. Ser. khim. 1970 857 (Chem. Abs. 1970,73 35483n). lob A. Jean G. Guillerm and M. Lequan J. Organometallic Chem. 1970,21 PI. lo' (a)Y. A. Ol'dekop N. A. Maier A. A. Erdman and Y. A. Dzhomidava Zhur. obshchei Khim. 1970. 40 300. (Chem. Abs. 1970 72 121662n); (b) ibid. p. 637 (Chem.Abs. 1970 73 35480n); (c) Y. A. Ol'dekop N. A. Maier and Y. D. But'ko ibid. p. 641 (Chem. Abs. 1970,73 14954h); (d)Y. A. Ol'dekop N. A. Maier A. A. Erdman and S. S. Stanoraya ibid. p. 305 (Chem. Abs. 1970 72 121663~). B. L. Dyatkin S. R. Sterlin B. I. Martynov and I. L. Knunyants Tetrahedron Letters 1970 1387. R. Fields R. N. Haszeldine and A. F. Hubbard Chem. Comm. 1970 647. D. J. Cardin M. F. Lappert J. D. Smith and D. R. M. Walton methanesulphonate has been obtained by SO insertion into Me,Mg,' lo" and the phenyl analogue and corresponding sulphinate prepared from Ph,Hg and PhS03H and PhS0,H respectively.' lob The compound reported previously as methylmercuric hydroxide has been shown to be a mixture of (MeHg),O and [(MeHg),O]+OH- but the phenyl analogue has been prepared"'" and some properties of (PhHg),O are reported.' 'lb Mass spectral studies of dialkyl- and diaryl-mercury and alkyl- mercury halide compounds are reported and structural correlations estab- lished.Group 111.-Boron. The B-C bond length in the crystal of Me,NBMe is 1.65 A.1l3 The first ionisation potentials ofa number of simple boron compounds including BEt (9.66eV) and C1,BEt (10.80 eV) have been determined and the results interpreted in MO terms.'I4 Thermochemical data on compounds I -RB-O(CH,);O RB(OEt) ,and RB.OCH(CH,CH,),CH-O have been obtained and ring-strain energies calculated." An e.s.r. study of the decomposition of [Ph,B]-Na+ in dimethoxyethane reveals that the derived Ph radical anion is formed from a single Ph,B radical anion by an intramolecular process.'16 - CPI CPI I+ PhMe + PhBBr ; -50 "CCPKO (Cp = ~c-C~HS) H (i) SnBr (ii) NH,PF,-H,O 1 co .Ph PF,- Ph' 'Br (14) In an interesting ring-expansion reaction the existence of an aromatic C,B ring stabilised by co-ordination to a cobalt atom is proposed;"' crystallo-graphic confirmation for (14) is clearly necessary.Further experiments on pentaphenylborole confirm its instability ;'l8 however a Diels-Alder adduct (15) of a related compound has been well characterised. Compound (16) was obtained from ArB(Cl)CH,Ph and PhCrCH.' 'lo (a) K. A. R. Salib and J. B. Senior Chem. Comm. 1970 1259; (b) G. B. Deacon and P. W. Felder Austral. J. Chem. 1970 23 1275. ''I (a) A. J. Bloodworth J.Organometallic Chem. 1970 23 27; (b) J. Chem. Sor. (a, 1970,2051. 'I2 W. F. Bryant and T. H. Kinstle J. Organometallic Chem. 1970 24 573. 'I3 G. J. Bullen and N. H. Clark J. Chem. SOC. (A) 1970 992. ''' M. F. Lappert M. R. Litzow J. B. Pedley P. N. K. Riley T. R. Spalding and A. Tweedale J. Chem. SOC. (A) 1970,2320. ' A. Finch P. J. Gardner P. M. McNamara and G. R. Wellum J. Chem. SOC. (A),1970 3339. 'I6 J. E. Leffler G. B. Watts T. Tanigaki E. Dolan and D. S. Miller J. Amer. Chem. SOC. 1970,92,6825. 'I7 G. E. Herberich G. Greiss and H. F. Heil Angew. Chem. Internat. Edn. 1970,9 805. 'IB P. J. Grisdale and J. L. R. Williams J. OrganometafficChem. 1970 22 C19. 'I9 P. I. Paetzold and H. G. Smolka Chem. Ber. 1970 103 289. Organometallic Compounds-Part (i) The Main Group Elements L Ph J (15) Lithium perhydro-9b-boraphenalyl hydride (17) obtained from hydroboration of cis,cis,trans-perhydro-9b-boraphenalene and subsequent reaction with LiH in THF is an active reducing agent of unusually high stereoselectivity for cyclic ketones.12' Li+ Further details have appeared of two rather unusual methods of B-C bond-making the ArH-BX (X = Br or I) photolytic conversion to ArBX2,I2' and the ArI-BI reaction to give ArBI,.'22 Ferrocene has been converted to (n-C,H,)Fe(C,H,BCl,-n) by treatment with B2Cl,.' 23 A simple high-yield synthesis of R2BC1 has been published,'24 using a combination of known reactions but without necessity for isolation of intermediates (Scheme 2).An unusual organoboron synthesis has been described (Scheme 3).12 120 H.C. Brown and W. C. Dickason J. Amer. Chem. SOC.,1970,92,709. I*' R. A. Bowie and 0.C. Musgrave J. Chem. Soc. (C),1970,485. W. Siebert Chem. Ber. 1970 103 2308; W. Siebert F. R. Rittig and M. Schmidt J. Organometallic Chem. 1970 25 305; W. Siebert K. J. Schaper and M. Schmidt ibid. p. 315; W. Siebert E. Gast and M. Schmidt ibid. 1970 23 329. J. C. Kotz and E. W. Post Inorg. Chem. 1970,9 1661. 124 L. F. Hohnstedt J. P. Brennan and K. A. Reynard J. Chem. SOC.(A) 1970,2445. Iz5 J. C. McMullen and N. E. Miller Inorg. Chem. 1970 9 2291. 284 D. J. Cardin M. F. Lappert J. D. Smith and D. R. M. Walton ,3(Me3SiCH2BH,) + Me,S -+ Me,SiCHSMe -1 BX 1 complex low temp. *Me,Si(Me)CHBMe, X = Me Scheme 3 Once again there have been upwards of fifty papers on aspects of carborane chemistry; the reader is referred to Volume (A) of Annual Reports.Compounds Me,Ti(R),-, have been obtained from Me,Ti and R,B (R = Ph or PhCH,).' 26 For some years it has been a curiosity that some N-chloroamines cleave a B-C bond in an opposite sense from others the problem has now been resolved by demonstrating that route (a) in Scheme 4 proceeds by a polar mechanism while (b)involves a free-radical pathway;'27 of potential synthetic utility is the suppression of (b)by addition of galvinoxyl. Scheme 4 Other organoboron free-radical systems which have been studied are (i) the CF,'-BMe reaction (efficiency BMe > SnMe >> GeMe xSiMe as radical traps);128 (ii) the kinetics of the RO*-BBu &2 reaction;'29 (iii) the Me2N'-BBu S,2 reaction (the first R2N*-MR reaction to have been studied);',' and (iv) the '9' ag-unsaturated carbonyl compound-BR reaction.' 32 Regarding (iv) the substrate R(Me)CHCH,COMe (ii) H,O R3B\LR(Me)CHCH2CH0 (i) MeCH "C THF cat.O, 25CHCHO (ii) H,O L (i)o,,25mc, cat. MeCOC j CH THF RCH CHCOMe (predominantly cis) (ii) H,O Scheme 5 126 P. Zdunnek and K. H. Thiele J. Organometallic Chem. 1970 22 659. A. G. Davies S.C. W. Hook and B. P. Roberts J. Organometallic Chem. 1970 23 Cll. 128 T. N. Bell and A. E. Platt Chem. Comm. 1970 325. lz9 A. G. Davies D. Griller B. P. Roberts and R. Tudor Chem. Comm. 1970 640. I3O A. G. Davies S. C. W. Hook and B.P. Roberts J. Organometallic Chem. 1970 22 c37. 131 G. W. Kabalka H. C. Brown A. Suzuki S. Henma A. Arase and M. Itoh J. Amer. Chem. Soc. 1970,92,710. L32 H. C. Brown and G. W. Kabalka J. Amer. Chem. SOC. 1970,92 712 714. Organometallic Compounds-Part (i) The Main Group Elements is either 'reactive' such as acrolein or 'inert' such as trans-crotonaldehyde ; in the latter system a radical pathway is promoted by traces of O, hv or other initiation procedures and inhibited by galvinoxyl. The 0,-induced reaction in particular has synthetic utility in combination with hydroboration for the con- version of an olefin into an aldehyde or ketone or an ap-unsaturated ketone (Scheme 5).132 Redistribution reactions have been described which make available some convenient procedures for synthesis of boronic esters,'33 1,2-tetramethylene- diboranes,' 34 and mixed trialkylboranes (which via carbonylation are sources of mixed trialkylcarbinols).' There has been interest in the species [R3BCN]- :136,137 they have been used as sources of ketones (Scheme 6).'37 R hydroboration NaCN 2 MeSO Na + I olefin ,2BR diglyme2[BRJCN] -Na+ ,2R2B-I+ C-NH I RB I 1 - 1 4HI + R,B/L%$IHI +- 2R,BC=NH HN /BR HN ;BR2 C R2 C R Other highlights in hydroboration during 1970 appear to be a convenient four-carbon-homologation (R3B + CH,BrCH CHC0,Et KtOC,H~.BU'Z-2.6 RCH :CHCH2C02Et);'38 a new aldehyde synthesis (R3B + N,CHCHO -P HgO RCH,CHO) an alkyl bromide synthesis via mercurials [R12B-R20H-H2,~ Br R2,Hg3R2Br; R' = s-or t-alkyl; RZ = n-alkyl];'40 another synthesis of prepara-mercurials [R3B Hg(OAC)z ' RHgOAc] ;14' a synthesis of acyclic diene~;'~ tion of terminal allenes (e.g.R,BH li) Bu"C=CCH'C',(ii) NaoH ' Bu"CH=C=CH,);'~~ and routes to cis-enynes 144 a/?-acetylenic ketones and &,cis-dienes (Scheme 7). Aluminium Gallium Indium and Thallium. There seems to be no reason to alter the established view that in solid trimethylaluminium the molecules form '33 H. C. Brown and S. K. Gupta J. Amer. Chem. SOC., 1970,92 6983. 134 H. C. Brown E. Negishi and P. L. Burke J. Amer. Chem. SOC., 1970,92 6649. 135 H. C. Brown E. Negishi and S. K. Gupta J. Amer. Chem. SOC., 1970,92 6648. 136 E. Brehn A. Haag and G. Hesse Annalen 1970 737 8 70.13' A. Pelter M. G. Hutchings and K. Smith Chem. Comm. 1970 1529. ' 38 H. C. Brown and H. Nambu J. Amer. Chem. SOC.,1970,92 1761. 139 J. Hooz and G. F. Morrison Canad. J. Chem. 1970,48 868. 140 J. J. Tufariello and M. H. Hovey Chem. Comm. 1970 372. 14' R. G. Larock and H. C. Brown J. Amer. Chem. SOC.,1970,92 2467. 142 J. A. Marshall and J. H. Babler Tetrahedron Letters 1970 3861. 143 G. Zweifel A. Horng and J. T. Snow J. Amer. Chem. SOC. 1970,92 1427. G. Zweifel and N. L. Polston J. Amer. Chem. SOC., 1970,92 4068. D. J. Curdin M. F. Luppert J. D. Smith und D. R. M. Wulton Bu” C-CBu” \/ H/c=c\D ~ Bu”C iCC .CBu” / (i) BH +Bu”CH,.CO.Ci CBU” \(Ii’ OH-“,O2 H H H’ H Scheme 7 symmetrical dimers (18; X = Y = Me)’45” in spite of a strange that the bonding in the bridge is not symmetrical with respect to the two alumin- ium atoms.Crystallographic studies have shown that in solid dimethylphenyl- aluminium (18; X = Y = Ph) phyl groups form electron-deficient bridges between Ph X I HM~ ,Al~e~ 0 t AIMe (19) aluminium and that in anions of the compound [Na(C,H,O),],- [AlMe2CloH,]2 aluminium atoms link the 1-4’ and 1’4 positions of 1,4-dihydro-1,4-naphthylene skeletons. 14’ Careful thermochemical work has shown that contrary to the usual belief tri-isobutylaluminium is partly associated to dimers at 20 0C.148The enthalpy of association (8.1 kcal(mole[R,Al],)-’>is about half that of triethylaluminium. The compounds MAlBu (M = R4N or alkali metal) are soluble in many organic solvents and have been used to study interactions between ion pairs and solvents.149 Several very reactive allylaluminium compounds have been i~olated.’~’ They undergo self-condensation reactions except at low temperatures. The reactivity 145 (a) F. A. Cotton Znorg. Chem. 1970 9 2804; M. J. S. Dewar and D. B. Patterson Chem. Comm. 1970 544; (b) S. K. Byram J. K. Fawcett S. C. Nyburg and R. J. O’Brien ibid. p. 16. 146 J. F. Malone and W. S. McDonald Chem. Comm. 1970,280. 14’ D. J. Brauer and G. D. Stucky J. Amer. Chem. SOC. 1970 92 3956. 14’ M. B. Smith J. Organometallic Chem. 1970 22 273. 149 J. L. Wuepper and A. I. Popov J. Amer. Chem. SOC. 1970,92 1493; T. D. Westmore- land N. Ahmad and M. C. Day J. Organometallic Chem.1970 25 329; J. F. Ross and J. P. Oliver ibid. 1970 22 503. I5O H. Lehmkuhl and D. Reinehr J. Orgdnometallic Chem. 1970 23 C25. Organometallic Compounds-Part (i) The Main Group Elements 287 of olefins with respect to addition of triphenylaluminium increases in the series Ph,C CH (giving PhCH,CPh,AlPh,) < oct-1-ene (giving C6Hl ,CPhCH,- AlPh,) < exo-5-phenylbicyclo[2,2,l]hept-2-ene< bicyclo[2,2,l]hepta-2,5-di-ene.' 5' Aluminium trialkyls add across the carbonyl group of methyl isopropyl ketone and across the nitrile group of acrylonitrile.' 52 When triethylaluminium reacts with epoxides the products depend on which reagent is in excess :with an excess of triethylaluminium one molecule complexes with the epoxide which is alkylated stereospecifically by a second molecule (Scheme 8)' 53 In the reduction *EtCH MeCH ,OH /O\ Et,Al + Me -CH -CH \(i) MeAH2 uEtCH,CHMeOH (11) HlO Scheme 8 of benzophenone by tri-isobutylaluminium the intramolecular elimination of but-1-ene from the complex Ph,COAlBu' is rate-determining.' 54 The reactions between trimethylaluminium and aldehydes or ketones yield unsymmetrically bridged derivatives (18; X = Me,Y = OCHPhMe OBu' OCPhMe, or OCPh,Me); others have been characterised by n.m.r.spectroscopy.' 55 The stereospecific polymerisation catalyst [Me,Al.OCPh.NPhCMeH.0] formed from acetaldehyde and the compound [Me,Al.OCPh.NPh] reacts with trimethyl- aluminium to give a crystalline derivative (19) which catalyses atactic polymerisa- tion of a~eta1dehyde.l~~ Aluminium alkyls have also been used to alkylate halides e.g to form compounds with quaternary carbon atoms or alkyl-germanium compounds.' 57 The presence of dimeric molecules (18; X = Y = NMe,) has been confirmed in solid dimethyl(dimethylamido)aluminium; trimers with the [AlN] ring in the skew-boat conformation are found in the solid compound [Me,AlN(CH,),] and in one isomer of the methylamido-derivative [Me,AINHMe] .In another isomer [Me,AlNHMe] molecules adopt a chair conformation with all N-methyl groups equatorial.' 58 The compounds [Et,AlNMe,] and [Et,AlSEt] 15' J. J. Eisch and S. J. Y. Liu J. Organometallic Chem. 1970 21 285. 15' A. R. Lyons and E. Catterall J. Organometallic Chem. 1970 25 351; W. Kuran S. Pasynkiewicz and J.Muszynski ibid. p. 23; W. Kuran and S. Pasynkiewicz ibid. 1970 23 343. 153 A. J. Lundeen and A. C. Oehlschlager J. Organometallic Chem. 1970 25 337. E. C. AshbyandS. H. Yu J. Org. Chem. 1970,35 1034. 55 E. A. Jeffery and T. Mole Austral. J. Chem. 1970,23 715; M. Fishwick C. A. Smith and M. G. H. Wallbridge J. Organometallic Chem. 1970 21 P9. 156 Y. Kai N. Yasuoka N. Kasai M. Kakudo H. Yasuda and H. Tani Chem. Comm. 1970 1243. 15' J. P. Kennedy J. Org. Chem. 1970,35 532; L. M. Antipin E. M. Stepina and V. F. Mironov Zhur. obshchei Khim. 1970 40 1 15 ;F. Glockling J. R. C. Light and R. G. Strafford J. Chem. SOC.(A) 1970 426. ' 58 H. Hess H. Hinderer and S. Steinhauser Z. anorg. Chem. 1970,377 I ;J. L. Atwood and G. D. Stucky J. Amer. Chem.SOC. 1970,92,285; K. Gosling G. M. McLaughlin, G. A. Sim and J. D. Smith Chem. Comm. 1970 1617. D.J. Cardin,M. F. Lappert J. D. Smith and D. R. M. Walton react with nitriles with addition across the triple bonds or with lactones with acyl-bond fis~ion.''~ The readily available thallium(II1) trifluoroacetate reacts with arenes to give the arylthallium compounds ArTI(OCOCF,) which may be converted to a variety of other products (Scheme 9)! 6o The formation of arylthallium compounds X- Ar2T10COCF3 -Ar,TIX(X = Hal) Scheme 9 from arenes (ArH) activated to electrophilic substitution needs only mild condi- tions; deactivated arenes must be heated under reflux. An important feature of the reaction compared with mercuration is that there is better control of isomers.Thus at room temperature thallation is mainly at the para-position except when there is an oxygen atom separated from the arene nucleus by less than two carbon atoms then e.g. when Ar = C,H,CO,Me ortho-substitution predominates perhaps through the interaction of thallium and oxygen in the transition state. The formation of iodides nitriles etc. from arylthallium bistrifluoroacetates may involve unstable compounds ArTlX (X = I or CN); the compounds ArTIX (X = F or C1) can however be isolated. Most alkylthallium compounds RTlX are unstable but the neopentyl derivative Me,CCH,TlBr has been made the unusual stability is attributed to the very slow decomposition by bimolecular T. Hirabayashi K. Itoh S. Sakai and Y. Ishii J. Organometallic Chem.1970 21 273; 1970,25,33; J. M. Lalancette Y. Beauregard and M. Bhereur Canad. J. Chem. 1970,48 1092. I6O A. McKillop J. S. Fowler M. J. Zelesko J. D. Hunt E. C. Taylor and G. McGillivray Tetrahedron Letters 1969 2423 2427; A. McKillop R. A. Raphael and E. C. Taylor J. Org. Chem. 1970,35 1670; E. C. Taylor F. Kienzle R. L. Robey and A. McKillop J. Amer. Chem. Soc. 1970 92 2175; E. C. Taylor H. W. Altland R. H. Danforth G. McGillivray and A. McKillop ibid. p. 3520; E. C. Taylor F. Kienzle and A. McKillop ibid. p. 6088; A. McKillop J. D. Hunt and E. C. Taylor J. Organometaffir Chem. 1970,24 77. 16' M. D. Johnson Chem. Comm. 1970 1037. Organometallic Compounds-Part (i) The Main Group Elements attack of halide on neopentyl. Reactions of methylallyl- and bisperfluorophenyl- thallium(I1r) compounds have been described the compound (C,F,),TlOH is a polymer in the cry~ta1.I~~ There are strong intramolecular interactions in solid trimethylthallium so that the carbon atoms round a thallium atom form a distorted trigonal bi~yramid.'~~ Spectral properties of the Me,In+ ion have been interpreted in terms of a linear structure.'650 Dimethylgallium hydroxide seems to show monomeric and dimeric species in solution.There is no evidence for the tetrameric [Me,GaOH] observed in the solid.165b Group1V.-Silicon* and Germanium. The so-called reductive silylation technique for forming carbonsilicon bonds advanced significantly during 1970 notably with the Mg-ZC1-HMPT system developed by Calas and co-workers as examplified in the following equations PhCN -+ PhC(Z)=NZ -+p-ZC6H,CH(Z)NZ2 (ref.166a) A r C 0Bu' -+ Arc( Z) (0Z)Bu' (ref. 166b) Me,C=CHCOCH =CMe -+ Me,C(Z)CH =C(OZ)CH=CMe (ref. 166c) PhOR -+PhCH,Z (R = Z Me or allyl) (ref. 166d) Z (ref. 166e) Buta-1.3-diene -+ ZCH,CH=CHCH,Z (ref. 166f) Ih2 H. Tada and R. Okawara J. Org. Chem. 1970 35 1666; T. Abe H. Kurosawa and R. Okawara J. Organometallic Chem. 1970 25 353; M. Tanaka H. Kurosawa and R. Okawara ibid. 1970 21 41; G. B. Deacon and J. C. Parrott ibid. 1970,22,287. Ih3 H. Luth and M. R. Truter J. Chem. SOC. (A) 1970 1287. Ih4 G. M. Sheldrick and W. S. Sheldrick J. Chem. SOC. (A) 1970 28. Ih5 (a)C. W. Hobbs and R. S. Tobias Inorg. Chem. 1970,9,1998; (b)L. Pellerito and R.S. Tobias ibid. p. 953. (a) C. Biran R. Calas J. Dunogues and N. Duffaut J. Organometallic Chem. 1970 22 557; (b) R. Calas J. Dunogues J-P. Pillot C. Biran and N. Duffaut J. Organo-metallic Chem. 1970,25,43; (c)R. Calas and J. Dunogues Compt. rend. 1970,270 C 855; (4 N. Duffaut C. Biran J. Dunogues and R. Calas J. Organometallic Chem. 1970 24 C5I ; (e) J. Dunogues R. Calas C. Biran N. Duffaut and P.Lapouyade J. Orgunometaflic Chem. 1970 23 (250; (f) J. Dunogues R. Calas J. Dedier and F. Pisciotti J. Organometallic Chem. 1970,25 51 ;(g)R. Calas and J. Dunogues Compr. rend. 1970 270 C 2012; (h)J. Dunogues R. Calas and N. Duffaut Buff. SOC. chim. France 1970,2016. * Z = Me,Si throughout this section. 290 D. J. Cardin M. F. Lappert J. D.Smith and D. R. M. Walton Additional related examples are noteworthy (ref. 166g) Buta-1,3-diene + Me,SiCl -+ GiMe2 (ref. 166f) Stilbene + Me,GeCl-+ PhCH(GeMe,)CH(GeMe,)Ph (ref. 166h) Unexpected products are sometimes encountered as for example in the reductive silylation of bistrimethylsilylacetylene ZCECZ -+ Z,CCH,SiMe,CH,Z + Z,CCH,SiMe,CHZ (ref. 167) Chlorosilanes can usefully be reduced to silicon hydrides by adaptation of the method + Me,SiCl bMe2SiH (75 (ref. 168) M;i:!cl-Further examples of newestablished procedures include MeCN ArC02H + HSiCl Pr,N +ArCH,SiCl (ref. 169) Pyridine + ZC1-Z-N,?Z (ref. 170) w Current interest in carbon compounds possessing geminal lithium and a Group IVB meta117'-'73 has led to improvements in the synthesis of halogenoalkyl derivatives PhHgCBr + R,MH -+R,MCBr,H (R = alkyl; M = Si or Ge) (ref.171) Bu"Li + ClzCHZ -ZCCl,Li AMe,SnCCl,Z (ref. 172) Me SnCl Bu"Li + Cl,CZ +Z,CClLi sZ,CClMe (ref. 172) PhLi ZCI Br,CLi + ZC1 -+ZCBr -ZCBr,Li --+Z,CBr (ref. 173) 167 L. C. Quass R. West and G. R. Husk J. Organometallic Chem. 1970,21 65. 168 R. Calas J. Dunogues and N. Duffaut J. Organometallic Chem. 1970 22 561. 169 R. A. Benkeser and J. M. Gaul J. Amer. Chem. SOC. 1970,92 720. R. A. Sulzbach J. Organometallic Chem. 1970 24 307. D. Seyferth and S. P. Hopper J. Organometallic Chem. 1970 23 99. 172 D. Seyferth E. M. Hanson and F. M. Armbrecht jun. J. Organometallic Chem. 1970 23 361. G. Kobrich and R. v. Nagel Tetrahedron Letters 1970 4693 4697.Organometallic Compounds-Part (i) The Main Group Elements 29 1 The latter reaction sequence is not so straightforward as appears at first sight since the following rapid interconversions occur ZCBr,Li + ZCBr -+Z,CBr + LiCBr (ref. 173) Z,CBrLi + LiCBr -+ 2ZCBr,Li (ref. 173) Useful information regarding isomeric organolithium species in solution can often be gained through couplings with organosilicon halides notably with ZC1 as illustrated by the examples from allene chemistry shown in Scheme 10.Organo-lithium and -magnesium intermediates from perhalogenohydrocarbons may PhC-CCH,Z + PhCH=C=CHZ PhCH=C=CHZ (ref. 174) PhC( Z) =C =CZ Ar,C=C=CBr + 2BuLi( -70 "C) ,clAr,C=C=CZ (ref. 175) Scheme 10 likewise be trapped (Scheme 11)' 76 Organosilyl ketones have attracted attention in recent years in part as a result of interest in their U.V.spectra. a-Silyl ketones c1,c=cclcc12ccl,ccl =CC12 *z,c =c=C(Z)C(Z)=C=CZ2 \Myr 1L-i THF-ZCI Li-THF-ZCI c1ncc12 CI CCI Scheme 11 are particularly difficult to prepare owing to the ease with which they rearrange. Adaptation of the aldimine ketone synthesis' 77 now provides a convenient route to these compounds. EtLi + Bu'CH,CMe,NrC + Bu!CH,CMe,N =C(Et)Li 3Bu'CH ,CMe,N =C( Et)Z ';.:";* ti IdII ZCOEt 174 J. Klein and S. Brenner Tetrahedron 1970 26 2345. G. Kobrich and E. Wagner Angew. Chem. Internat. Edn. 1970,9 524. 176 D. H. Ballard T. Brennan and H. Gilman J. Organometaffic Chem. 1970 22 583. '77 H.M. Walborsky W. H. Morrison and G. G. Niznik J. Amer. Chem. SOC.,1970 92 6675. D. J. Cardin M. F. Luppert J. D.Smith and D.R. M. Wulton Examples of recently synthesised organosilyl ketones include Me' Me Z Br (ref. 178a) (ref. 178b) (ref. 178b) (ref. 178c) The reactions of carbon monoxide with t-butyl- trimethylsilyl- and phenyl- lithium and also of bis-trimethylsilyl and -triethylgermyl ketone with n-butyl- lithium are of interest in the ketone context. Representative carbonsilicon cage ZLi + CO -+ZCOLi -+ LiO OLi zo oz (ref. 179) PhLi + CO -+ Ph,C(Li)COPh %Ph,C(Z)COPh (ref. 180) Bu'Li + CO -+ Bu'COLi ZBu'COZ (ref. 180) HO R,C=C=O + Bun Li -R,C=C(Bu")OLi A R,CHCOBu" lH& RCH=C(Bu")OR (R = Z or GeEt,) (ref.181) structures (carborundanes) (20H22)' 82 have been isolated in small quantities by pyrolysis of tetramethylsilane at 700 "C;however (20)can readily be obtained Me Me Me Me Me (20) (21) (22) 178 (a) W. P. Weber and R. Laine Tetrahedron Letters 1970 4169; (6) H. G. Kuivila and G. L. Grady J. Organometallic Chem. 1970 21 303; (c) R. J. P. Corriu and J. P. Masse ibid. 1970 22 321. 179 P. Jutzi and F-W. Schroder J. Organometallic Chem. 1970 24 C43. 180 P. Jutzi and F-W. Schroder J. Organometallic Chem. 1970 24 1. 181 S. V. Ponomarev and S. A. Lebedev Zhur. obshchei Khim. 1970,40,939. 182 G. Fritz F. Diem H. Koehler D. Kummer and H. Scheer -4ngew. Chem. Internat. Edn. 1970,9 464. Organometallic Compounds-Part (i) The Main Group Elements 293 in 80 % yield by AlBr,-catalysed redistribution within the monocyclic unit (Me,SiCH,)3 Pyrolysis of chlorosilyl compounds gives sila-fluorene and -acenaphthylene derivatives in good yield /\ (ref.184) SiCI3 c1’ ‘c1 FH2SiHC12 (55 %) (ref. 185) -a 600-680°C Synthetically useful reorganisations have been reported in the polysilane series cyclo(Me,Si) %cyclo(Me,Si) + cyclo(Me,Si) (ref. 186) (major product) ZSiMe2H trans-(Et P) PtCI, 90°C. ,8h ’ZH + Z(SiMe2),H(2 < n < 5) (ref. 187) Z.Z + ZC1 AICI,’C~M~~S~S~M~,C~ (ref. 188) (93 x) Z4C + ZC1 A,C, F(ClMe,Si),C (88 %) (ref. 188) Z*(CH2)4.Z+ ZC1 AICI,C~S~M~~(CH,),S~M~,CI (ref. 188) (96 %) Examples of novel syntheses potentially useful for carbon-functional compounds are as follows R SiEt, alkoxide + Et,SiH C,H,-I >=( (R = Me or But) (ref.189) Me H 183 C. L. Frye J. M. Klosowski and D. R. Weyenberg J. Amer. Chem. Soc. 1970 92 6379. E. A. Chernyshev S. A. Shchepinov and T. L. Krasnova Zhur. obshchei Khim. 1970,40 1958. E. A. Chernyshev and N. G. Tolstikova Zhur. obshchei Khim. 1970,40 1052. M. Ishikawa and M. Kumada Chem. Comm. 1970 612. “’ K. Yamamoto H. Okinoshima and M. Kumada J. Organometallic Chem. 1970 23 C7. M. Ishikawa M. Kumada and H. Sakurai J. Organometallic Chem. 1970 23 63. M. S. Newman and C. D. Beard J. Amer. Chem. SOC., 1970,92,4309. D. J. Curdin M. F. Luppert J. D. Smith and D. R. M. Wulton 2,Hg + PhHgCC1,Br +ZCC1,HgZ -+ZCCI2CCl2HgZ 1 ZCIC=CCl + [ZHgCI] (ref.190) R'R2Ge(OMe)H + CH,=CR3CR4=CHR5 -+ (ref. 191) R2 MCl + CH,=C(NMe,) -+C1,MCH2CC1(NMe2) %Cl,MCH=C(NMe,) (M = Si or Ge) (ref. 192) Hydrosilylations of olefins catalysed either by peroxides or by U.V. light have been reported previously. These two methods have now been combined in an attractive low-temperature process. Bu'O'-hv C1,SiH + oct-l-ene ~n-CsH1,SiC13 100%) (ref. 193) (-The range of transition-metal hydrosilylation catalysts has been extended to complexes containing nickel,194a cobalt and rhodium.194b Care must be exercised however when aminosilanes are used as redistribution may precede hydrosilylation. 2Bu"NHSiMe,H SBu"N(SiMe,H) + Bu"NH (ref. 195) Organosilicon rearrangements continue to feature prominently both as regards improvements to and elucidation of existing rearrangements.Several novel processes have been reported. For example allyltrimethylsilane rearranges at 500 "C to trimethylvinylsilane and tetramethylsilane as in Scheme 12.'96 'CH ZCH=CH + :CH ZH4MeZ Scheme 12 Novel examples of silicon and germanium migrations (E +C C +C and C -P N) have been reported. lYoD. Seyferth E. M. Hanson B. Prokai and R. J. Cross J. Organometallic Chem. 1970 24 33. M. Massol P. Riviere J. Barrau and J. Satge Compt. rend. 1970 270 C 237. lYzH. Weingarten and J. S. Wagner Chem. Comm. 1970 854. Ig3 S. W. Bennett C. Eaborn and R. A.Jackson J. Organometallic Chem. 1970 21 79. lg4 (a)M. Kumada Y. Kiso and M. Umeno Chem. Comm. 1970 61 1 ;(b)A. J. Chalk J. Organometallic Chem.1970 21 207. Iy5 W. E. Dennis and J. L. Speier J. Org. Chem. 1970,35 3879. H. Sakurai A. Hosomi and M. Kumada Chem. Comm. 1970,767. Organometallic Compounds-Part (i) The Main Group Elements ether p-Li.C6H4.SMR3 *p-R3M.C6H4.SLi (R3M = Z or Me3Ge) (ref. 197a) 24 h Z,CNC =[Z,CCN] +Z,C=C=NZ (ref. 197b) PhMe,Si(CH,),~H -+ Et,GeCH,CONH Me 140p sooc b MeCON(Me)GeEt (ref. 197d) Chloromethyl(trimethyl)silane,catalysed by SbF rearranges in homogeneous solution (in acetronitrile) to chloro(ethyl)dimethylsilane.'98 Evidence for silacyclopropenium ion intermediates is provided by the following observations ZCD,CH,Br =ZCH2CD2Br (ref. 199a) ZCH,CD,OH PBr,ZCH,CD,Br + ZCD,CH,Br (ref. f99b) The facile acid-catalysed fragmentation of P-hydroxyalkylsilicon compounds provides the basis for a potentially useful olefin synthesis e.g.ZCH,MgCl + R'R2C0 +R'R2C(OH)CH2Z H,O+bR'R2C=CH2 (ref. 200) K'K2C=0 PhCH2Z + BuLi-HMPT +PhCHLiZ -R1R2C=CHPh (ref. 200) Coupling with an acyl halide followed by hydrolysis yields a ketone ZCH,MgCl + RCOCI-+RCOCH,Z +RCOMe (ref. 200) Extensive studies of silacyclobutane ring-opening reactions as a route to organo- metallic sultones have been reported (Scheme 13). Continued interest in novel (ref. 20 1a) (ref. 201b c) Scheme 13 19' (a) A. R. Bassindale and D. R. M. Walton J. Orgunomerallic Chem. 1970 25 389; (b) R. West and G. A. Gornowicz J. Organometallic Chem. 1970 25 385; (c) J. W. Wilt and C. F. Dockus J. Amer. Chem. Soc. 1970,92,5813; (6)Yu. I. Baukov G.S. Burlachenko A. S. Kostyuk and I. F. Lutsenko Zhur. obshchei. Khim. 1970,40 707. 19' T. J. Hairston and D. H. O'Brien J. Organometallic Chem. 1970 23 C41. 199 (a) M. A. Cook C. Eaborn and D. R. M. Walton J. Organometallic Chem. 1970,24 301 ; (6)A. J. Bourne and A. W. P. Jarvie J. Organometallic Chem. 1970,24,335. *O0 T. H. Chan E. Chang and E. Vinokur Tetrahedron Letters 1970 1137. 20' (a)J. Dubac P. M. Mazerolles M. Joly W. Kitching C. W. Fong and W. H. Atwell J. Organometallic Chem. 1970,25 C20;(6)J. Dubac P. Mazerolles and M. Joly ibid. 1970,22 C7; (c)J. Dubac P. Mazerolles M. Lesbre and M. Joly ibid. 1970,25 367. 296 D. J. Cardin M. F. Lappert J. D. Smith and D. R. M. Walton small-ring silicon compounds is typified by synthesis of cyclic silylalkylidene- phosphoranes (Scheme 14).K (i) Me Sic1 Me,P =CH2 + Me2SiC12+ Me2Si %Me2 Me,P=CZ (ii) [Me,P(CH,),]Li K (ref. 203) PMe (ref. 202) Scheme 14 Tin and Lead. In contrast to silicon consolidation of existing methods rather than the opening up of new areas of synthesis characterises organo-lead and -tin chemistry. One radically novel structure has been described however ; thus treatment of the carbollide ion (3)-1,2-B,C,Hl 12-with metal halides MX (M = Ge Sn or Pb) leads to formation of l-rnetalla-2,3-dicarba-cZuso-dode-caboranes (1 l),(23).,04 0BH Intermediates containing tin or lead bonded to lithium or magnesium are used increasingly in the preparation of unsymmetrical derivatives (Scheme 15),205 owing to their capacity to couple with halides rather than to undergo metal-halide exchange.The work with tin has received impetus with the discovery of a novel metallation. Bu3SnH + RMgX Bu3SnD Bu,SnSiMe Bu,SnMgX 145 Bu,Sn(allyl) <=cH >Bu,SnCMe,OH Scheme 15 202 H. Schmidbaur and W. Malisch Chem. Ber. 1970 103 97; H. Schmidbaur and W. Malisch Angew. Chem. Internat. Edn. 1970 9 77. 203 H. Schmidbaur and W. Malisch Chern. Ber. 1970 103 3007 3448. 204 R. W. Rudolph R. L. Voorhees and R. E. Cochoy J. Amer. Chem. SOC.,1970 92 3351. 205 J. C. Lahournere and J. Valade Compt. rend. 1970 270 C 2080; J. C. Lahournere and J. Valade J. Organometallic Chem. 1970 22 C3. Organometallic Compounds-Part (i) The Main Group Elements 297 New species R,PbMgCl (R = Me3SiCH,,206 Me3CCH2,’” Me,”* or EtZo8) have been made from the appropriate Grignard reagent and PbC12 in THF.The intermediates Ar,PbMgCl react with dihalogenomethanes to give hexa-aryldiplumbanes in excellent yield.209 Ar,PbMgCl + CH,X -+Ar,PbPbAr (X = Br or C1) (Ar = Ph; o- m-,p-tolyl; p-anisyl; 1-or 2-naphthyl) Organolithium compounds prepared analogously react cleanly with alkyl halides to give lead-substituted alkanes PhLi + PbC1 iTHF HCCl (Ph3Pb)3CH-Ph,PbLi%(Ph,Pb),C (ref. 210) R,MLI + ClCH=CHCH=CH +R,MCH=CHCH=CH (M = Pb or Sn; R = Et or Ph) (ref. 211) Me,SnLi + CF,COCl -+CF,COSnMe (ref. 212) It is relevant to note that the lead-substituted dichloromethanes react with butyl-lithium at low temperature ( -75 “C)with rupture of only one carbon-lead bond ‘ (Ph3Pb),CC1 Ph,PbCCI,HgPh PhHgCL * Ph PbCCl Li Ph PbCCl SnPh Ph,SnCI (ref.213) Isomeric butadienylmetal compounds may be prepared directly from the Grignard reagent and trialkylmetal halide.’ l1 R MX CH,=C=CHCH,Cl% CH,=CHC(MgCI)=CH 3CH,=CHC(MR,)=CH (M = Pb or Sn; R = Et or Ph) Diazoalkanes insert into tin-hydrogen bonds but not apparently into ger- manes and silanes. (CF,),CN2 + Me,SnH -+ Me,SnC(CFJ,H (ref. 214) Tin (and silicon) also activate B-CH bonds towards carbene-type insertions and a wide range of compounds prepared by this technique have now been de~cribed.”~ ’06 K. C. Williams J. Organometallic Chem. 1970 23 465. ’07 K. C. Williams J. Organometallic Chem. 1970 24 399 ’08 K. C. Williams J.Organometallic Chem. 1970 22 141. 209 L. C. Willemsens and G. J. M. van der Kerk J. Organometallic Chem. 1970,21 123. 2Lo L. C. Willemsens and G. J. M. van der Kerk J. Organometallic Chem. 1970,23 471. 211 E. C. Juenge T. E. Snider and Y-C. Lee J. Organometallic Chem. 1970 22,403. 212 E. Lindner and U. Kunze J. Organometallic Chem. 1970 21 P19. C. M. Warner and J. G. Noltes J. Organometallic Chem. 1970,24 C4; C. M. Warner and J. G. Noltes Chem. Comm. 1970 694. W. R. Cullen and M. C. Waldman Canad. J. Chem. 1970,48 1884. 215 D. Seyferth S. S.Washburne C. J. Attridge and K. Yamamoto J. Amer. Chem. Soc. 1970,92,4405. D. J. Cardin M. F. Lappert J. D. Smith and D. R. M. Walton Me3MCH2CH2Me+ PhHgCC1,Br -+Me,MCH,CH(CCl,H)Me + PhHgBr (M = Sn or Si) Hydrostannylation of o-diethynyl-and o-divinyl-benzene with organotin dihydrides provides a route to novel heterocycles.216 These reactions are of use since subsequent iodinolysis (C-Sn bond rupture) is a stereospecific process.Dibenzostannoles are obtained by heating diphenyltin pentamer with bi- phenylene.2l7 /\ 0;J Ph’ ‘Ph A reaction of considerable potential is the methoxide-catalysed addition of hexa-alkyl-distannanes (and -digermanes) to unsaturated systems.2 ’* HMPT Me,M + PhC-CPh -Ph(MMe,)C=C(MMe,)Ph H MPT Me M ,+ Ph(C -C),Ph NaOMe Ph(M Me,)C =C(M Me,)( M Me,)C=C( MMe,)Ph (M = Ge or Sn) New methods of tin-carbon bond making have been described using R3SnNMe2 and either alkenes or alkynes with electronegative sub~tituents,~ 19a or C6F5H + (R,SnC,F,).’ 19b Additional aids to the synthesis of unsymmetrical organotin compounds are provided by the observation that the well-documented redistribu- tions between alkyl- and alkylhalogeno-stannanes are catalysed by U.V.irradiation at ambient temperatures EtSnC1 (2 moles) + EtSnPh (1 mole) &EtPhSnCl (90%) (ref. 220a) The thermal process requires heating to 140 “C for 1.5 h to achieve a comparable result. Non-volatile organotin halides key intermediates in synthesis are notoriously difficult to obtain pure. A novel method which avoids tedious ’I6 A. J. Leusink A. J. Budding and J. G. Noltes J. Organometallic Chem. 1970,24 375. ’’ J. M. Gaidis J. Org. Chem. 1970 35 281 1. ” E. J. Bulten H. A. Budding and J.G. Noltes J. Organometallic Chem. 1970 22 C5. (a)G. Chandra A. D. Jenkins M. F. Lappert and R. C. Srivastava J. Chem. Soc. (A) 1970 2550; (b)A. D. Jenkins M. F. Lappert and R. C. Srivastava J. Organometalfic Chem. 1970,23 165. ’*’ (a) L. S. Mel’nichenko N. N. Zemlyanskii and K. A. Kocheshkov Doklady Akad. Nauk S.S.S.R. 1970 190 597; (b) G. J. D. Peddle and G. Redl J. Organometallic Chem. 1970,23,461. Organometallic Compounds-Part (i)The Main Group Elements 299 purification involves conversion of the iodide to the sparingly soluble fluoride which can easily be crystallised from methanol followed by generation of the chloride by quantitative halide-halide exchange with chlorotrimethylsilane.220 Further details published regarding the insertion of sulphur dioxide into carbon-lead and -tin bonds depict the reaction as a typical electrophilic insertion process.221b Thus with tetra-alkyl or -aryl metal derivatives insertion of one mole of SO takes place readily at low temperature whereas higher temperatures are required for the reaction of further moles of SO R,Sn + SO =RSO,SnR (R = Me or Et) (ref.221a) Me,Sn + SO2 (MeSO,),Sn (ref. 221b) All products are demonstrated by spectroscopic criteria to possess 0-sulphinate structures with a considerable degree of aggregation in both solid phase and in solution.221bd Carbon-lead are generally more reactive than carbon-tin bonds., Disproportionation and rearrangement may accompany insertion 24 h Ph,MCI + SOz=Ph,M(O,SPh) + Ph,MC12 (M = Sn or Pb) (ref.221e) Me3SnCH=C=CMez *Me3Sn0,SCMe2CZCH (ref. 221f) The Sn-C,H bond is labile:222” thus Me,Sn-C,H oxidatively cleaves bi- nuclear complexes [e.g. Mn(CO), -+ (Z-C,H,)M~(CO)~ + Me,SnMn(CO),]. Carbon disulphide reacts with tetra-alkyl-lead compounds in an autoclave ; however the primary products are unstable and decompose upon warming e.g. Et,Pb + CS -+ Et,PbS,CEt -+ PbS + organosulphur compounds (ref. 222b) Sulphuryl chloride and N-bromosuccinimide serve excellently as mild halo- genodemetallating reagents slow RdPb + SOzClz .-) R3PbCl --+R,PbCl (ref. 223) 0 0 221 (a) G. Vitzthum U. Kunze and E. Lindner J. Organometallic Chem. 1970 21 P38; (b)E. Lindner U. Kunze G. Ritter and A. Haag ibid. 1970,24 119; (c)C. W. Fong and W. Kitching ibid.1970,21 365; (dj C. W. Fong and W. Kitching ibid. 1970 22 95; (e) E. Lindner and U. Kunze ibid. 1970,23 C53;(f)C. W. Fong and W. Kitching, ibid. 1970 22 107. 222 (a) E. W. Abel S. A. Keppie M. F. Lappert and S. Moorhouse J. Organometallic Chem. 1970,22 C31; (6) R. Gelius and E. Kirbach Z. Chem. 1970 10 117. 223 R. Gelius Z. anorg. Chem. 1970 374 297. ”* J. C. Maire R. Prosperini and J. Van Rietschoten J. OrganometafficChem. 1970,21 P41; B. C. Pant ibid. 1970 24 697. D. J. Cardin M. F. Lappert J. D. Smith and D. R. M. Walton An adaptation of the sulphuryl chloride reaction finds use in a novel cyclopropane synthesis e.g. Me,SnH + CH2=CHCRzOH +Me,Sn(CHz)2CR20H + Me,SnCI + wR R (ref. 225) Brominolysis of carbon-tin bonds is usually depicted as proceeding via a mole- cular rather than a radical reaction path.Evidence to the contrary is now inferred from the reaction of bromine with the optically active cyclopropane (Scheme 16),226 where loss of activity accompanies cleavage. An observation of use in Ph Me -phqIe + Br2 4-:MIe Ph MSnMe Ph Scheme 16 carbon-functional organolead chemistry is that p-aminophenyltriphenylplum-bane can be successfully diazotized under aprotic conditions and coupled with /3-naphthol without rupture of the aryl-lead A careful reinvestigation of the only reported resolution of an asymmetric organotin compound228 shows that the original claim was probably based upon erroneous results.229 This finding is compatible with recent n.m.r. studies indicating rapid inversion at tin in asymmetric halides R'R2R3SnX.An observation of considerable importance in mechanistic studies is that H/D isotope product ratios (i.e. X.C6H4*H/X*C6H,*D; X*C6H4.CH2H/X*C6H4 CH,D) in the base-catalyzed cleavage of aryl- and benzyl-tin bonds differ from the solvent isotope ratios (MeOH/MeOD) thus demonstrating that free carban- ions are not involved in these reactions.230a Full details are now available of the synthesis and characterisation of the series (Me,M),CN (M = Ge Sn or Pb) and on the M-C (M = Sn) cleavage re- actions ;230b a corresponding silicon diazoalkane does not form. Group V.-Phosphorus. Established methods for formation of P-C bonds have been used to prepare derivatives with bulky groups e.g. mesityl t-butyl and per~hlorophenyl,~~' and a neat route to the phosphines R'R2R3P has been 225 D.D. Davis R. L. Chambers and H. T. Johnson J. Organometallic Chem. 1970 25 C13. 226 K. Sisido T. Miyanisi T. Isida and S. Kozima J. Organometallic Chem. 1970,23 1 17. 22' D. C. Livingston J. Organometallic Chem. 1970 25 433. 228 W. J. Pope and S. J. Peachey J. Chem. SOC.,1900,42. 229 G. J. D. Peddle and G. Redl. J. Organometallic Chem. 1970 22 139. 230 (a) R. Alexander C. Eaborn and T. G. Traylor J. Organometallic Chem. 1970 21 P65; (b) M. F. Lappert and J. S. Poland J. Chem. SOC. (A) 1970,2954. 23 ' L. K. Il'ina K. V. Karavanov E. N. Karpova A. I. Bokanov and B. I. Stepanov Zhur. obshchei Khim. 1970,40,581;P. C. Crofts and D. M. Parker J. Chem. SOC.(0,1970 332 2529; A. P. Stewart and S. Trippett ibid. p. 1263; Chem. Comm. 1970 1279; 0.J. Scherer and W. Gick Chem. Ber. 1970 103 71; W. Kuchen and G. Hagele, ibid. pp. 21 14 2274; S. S. Dua R. C. Edmondson and H. Gilman J. Organometallic Chem. 1970,24,703. Organometallic Compounds-Part (i) The Main Group Elements 30 1 described.232 (RIP) -LiPR1R2 -!%R1R2R3P a[R1R2R3PMe]+I- LiR' Other methods for making P-C bonds include the photochemical addition of secondary phosphines to alkene~~~~ and the electrochemical reduction of phosphorus in the presence of alkenes or aldehydes.234 This last method at present gives rather low yields. The reaction between calcium carbide and chlorodiphenylphosphine provides new syntheses for tetraphenyldiphosphine and diphenylphosphinic anh~dride.~ CaC,; 15OoC;20h 0 Ph PCI Ph2 PPPh2 Ph,P(O)+P(O)Ph, Ph2PC1 -2c.-CaCI ' Aryl halides have been converted to phosphonates and phosphinates by trialkyl phosphites or dialkyl phosphonites in the presence of nickel salts.236 ArX + RP(OEt) *RArP(O)OEt (R = Ph or OEt) Further light has been shed on the relations between structure and reactions of organophosphorus compounds. Thus ring strain in phosphetans (24; X = C1 or Ph) shown by ready ring-opening and -expansion has been further confirmed by crystallographic studies which show C-C bonds of 1.61 A. The P-C bonds (1.84 A) are comparable with P-C(sp3) bonds in a number of other rnolec~les,~~~~~~~ e.g. (25) and (26). Shorter P-C(sp2) bonds (ca. 1.75A) appear in triphenylphosphine the P'"and Pv phosphorins (27; R = Me) and (28; R = Me or NMe,)241 and in 1-benzylphosphole (29; R' = R2 = H 232 M.Schmidt and W. R. Neeff Angew. Chem. Internat. Edn. 1970,9 807. 233 R. Fields R. N. Haszeldine and J. Kirman J. Chem. SOC. (0,1970 197; R. Fields R. N. Haszeldine and N. F. Wood ibid. pp. 744 1370. 234 L. V. Kaabak N. Ya. Shandrinov and A. P. Tomilov Zhur. obshchei Khim. 1970,40 584. 235 E. J. Spanier and F. E. Caropreso J. Amer. Chem. SOC. 1970,92 3348. 236 P. Tavs Chem. Ber. 1970,103 2428. 237 J. R. Corfield M. J. P. Harger J. R. Shutt and S. Trippett J. Chem. SOC. (0,1970 1855; J. R. Corfield M. J. P. Harger R. K. Oram D. J. H. Smith and S. Trippett, Chem. Comm. 1970 1350; J. R. Corfield and S. Trippett ibid.p. 1267; B. R. Ezzell J. Org. Chem. 1970 35 2426. 238 Mazhar-ul-Haque J. Chem. SOC. (B) 1970 934 938 71 1. 239 J. D. Lee and G. W. Goodacre Actcr Crysr. 1970 B26 506. 240 G. Bandoli G. Bortolozzi D. A. Clemente U. Croatto and C. Panattoni J. Chem. SOC.(A) 1970 2778. 241 J. C. J. Bart and .I..I.Daly J. Chem. So(,.(A) 1970 567; J. J. Daly ibid. p. 1832; U. Thewalt C. E. Bugg and A. Hettche Angew. Chem. Internat. Edn. 1970,8 898. D. J. Cardin M. F. Lappert J. D. Smith and D. R. M. Walton R3= CH2Ph).242A low barrier to pyramidal inversion at phosphorus has been detected in the phosphole (29; R' = Me R2 = Ph R3 = Pr') and this has been OR* R I phbph R2 R3 (28) R' (29) (27) ascribed to delocalisation of the lone pair in the transition state.243 The phos- phorin (27; R = Ph) reacts with hexacarbonylchromium to give (C,H,Ph,P)Cr- (CO),,and thus resembles benzene.244 The rates of pyramidal inversion of acylic phosphines R'R2MeP show activa- tion parameters AGt 29-36 kcal mol-' at 1300C.245 Steric effects are not significant.Inversions in diphosphines MeArPPArMe and in MePhP(S)PMePh are easier than in monophosphines possibly indicating p,-d interactions.246 The free-radical addition of methyl methylphosphinate to alkenes seems to be stereospecific suggesting that phosphinyl radicals RO(Me)PO like corresponding silyl radicals are ~hira1.~~' Menthyl penylphosphinate may be stereospecifically alkylated to give either isomer of the tertiary phosphine oxide (30).248 Me /Pri (i) Pr'l NaH O=P--H /OMenthyl (i) Mel NaH / O=P--Me -FO=P--Pr' \ (ii) MeLi \ (ii) Pr'MgBr \ Ph Ph Ph (304 (30b) It has been suggested that displacements at phosphorus in four-membered rings involve intermediates in which the ring spans apical and equatorial posi- tion~.~~~ However reactions may be faster or slower relative to acyclic phos- phines depending on the electronegativity of the leaving group and in certain cases stereospecificity is lost.Displacements in five-membered rings have also been studied.250 The stereochemistry of the cleavage of benzyl groups from "' P. Coggon J. F. Engel A. T. McPhail and L. D. Quin J.Amer. Chem. SOC.,1970,92 5779. 243 W. Egan R. Tang G. Zon and K. Mislow J. Amer. Chem. SOC., "'J. Deberitz and H.Noth Chem. Ber. 1970,103,2541. 1970,92 1443. 245 R. D. Baechler and K. Mislow J.Amer. Chem. SOC.,1970,92,3090,4758. 246 J. B. Lambert G. F. Jackson and C. D. Mueller J. Amer. Chern. SOC.,1970,92 3093. 247 H. P. Benschop and D. H. J. M. Platenburg Chem. Comm. 1970 1098. 24a W. B. Farnham R. A. Lewis R. K. Murray and K. Mislow J. Amer. Chem. SOC. 1970,92,5808; W. B. Farnham R. K. Murray and K. Mislow ibid. p. 5809. 249 J. R. Corfield N. J. De'ath and S. Trippett Chem. Comm. 1970 1502; P. Haake R. D. Cook T. Koizumi P. S. Ossip W. Schwarz and D. A. Tyssee J. Amer. Chem. Soc. 1970,92 3828. 250 W. Egan G. Chauviere K. Mislow R. T. Clark and K. L. Marsi Chem. Comm. 1970 733. Organometallic Compounds-Part (i) The Main Group Elements phosphonium salts involving six-membered rings has been described ;cleavage from bisphosphonium salts is non-stereospe~ific.~~ 2-Substituted derivatives of 1-phenylphospholan (31)obey the general rule that the group cleaved preferenti- ally is the one forming the most stable anion.252 The stability of cyclic phosphoranes such as (32) or (33) may derive from the ability of the five-co-ordinate phosphorus to accommodate the ring angles.253 An extensive series of ylides has been made from chlorosilanes and trialkyl- phosphines and.migration of the trimethylsilyl group to the ylide carbon has been documented.The silicon atom appears to stabilise the ylide by delocalisation of negative charge.20 29203 R3P + Me,H -,SiCH,CI -+ [R,PCH2SiMe,H3-,]C1 -+ R3P CHSiMe,H,_ Me,P + Me3SiCMe,C1 -+Me,Pr'P CHSiMe There are many examples of reactions between ylides and carbonyl functions.For example a modification of the Wittig olefin synthesis has permitted stereo- specific synthesis of the olefins (34) from the aldehydes RCHO ethylidenetri- phenylphosphorane and paraformaldehyde.* 54 Bisylides and vinylphosphonium salts have been used for the formation of ring The product isolated CH CH, H Me \/ Ph,P4 \PPh Ph2P' \hPh2 c=c \ /I \\ I/ R /\ HC-C C-C C'H,OH /\ /\ Me0,C C0,Me Me0,C C0,Me (34) (35) (36) in the reaction between the bisphosphine (Ph2P),CH2 and the alkyne Me0,C C-C-CO,Me is the diphosph(v)ole (35) formed by a proton shift from the 251 K. L. Marsi and R. T. Clark J. Amer. Chem. SOC.,1970 92 3791 ; G.E. Driver and M. J. Gallagher Chem. Comm. 1970 150. z52 B. R. Ezzell and L. D. Freedman J. Org. Chem. 1970 35 241. 253 E. M. Richards and J. C. Tebby J. Chem. SOC.(0,1970 1425; T. J. Katz and E. W. Turnblom J. Amer. Chem. SOC.,1970 92 6701. 254 E. J. Corey and H. Yamamoto J. Amer. Chem. SOC.,1970,92 226. 255 W. H. Ploderand D. F. Tavares Canad.J. Chem. 1970,48,2446; P. J. Garratt K. P. C. Vollhardt and R. H. Mitchell J. Chem. SOC.(0,1970 2137; E. E. Schweizer C. S. Kim and R. A. Jones Chem. Comm. 1970 39; E. E. Schweizer W. S. Creasy J. G. Liehr M. E. Jenkins and D. L. Dalrymple J. Org. Chem. 1970 35 601. 304 D. J. Cardin M. F. Lappert J. D. Smith and D. R. M. Walton intermediate (36).256 The ylide (Ph,P)2C reacts with pentacarbonylmanganese bromide to give the compound (CO),BrMn :C :C PPh and triphenylphosphine Phosphonates have been used in a number of related ketone syntheses.258 For example the compounds (RO),P(0)CH,CR'=CR20Et con-vert ketones R3R4C0 into derivatives R3R4C=CHCR'=CR20Et which are hydrolysed to R3R4CHCH=CR'COR2.The reactions of ylides with a-halogeno-carboxylic esters give new syntheses of ap-unsaturated acids and reactions with acyl chlorides give a-branched P-ketocarboxylic acids (Scheme R' R' R3 \ \/ 2 ,C=PPh + R3CHXC02R4-+ ,C=C + PPh, \ R2' R2 ' C02R4 + [R'R2HCPPh3]+X-(X = hal) R3 I R'\ C=PPh + R4-C-CO-Cl + / I R202C R5 R3 R' I I c1-electrolysis R~-C-CO-C-H -PPh I R5 C02R2 ' 17).259 The reaction between an ylide from R6R7R8P and an acyl chloride has been developed into a method for the determination of the absolute configuration of carboxylic acids.The reaction between ylides and nitrosyl chloride yields compounds [Ph,PC( :NOH)R]+Cl- and iminophosphoranes have been made from ylides and nitriles or from azido-compounds and triphenylphosphine.260 R'CN + Ph,P:CR2R3+Ph,P=N-C=CR2R3 I R' In the compound Ph,FP NMe the P-N bond is short (1.64 The reaction of phosphorus compounds with 2-iodoalkyl azides provides a convenient route to aziridines (Scheme 18).262 Arsenic Antimony and Bismuth. The ' n.m.r. nuclear quadrupole resonance and mass spectra of compounds Ph,M (M = As Sb or Bi) and I2lSb Mossbauer 256 M. A. Shaw J. C. Tebby R. S. Ward and D. H. Williams J. Chem. SOC.(C),1970,504. '" D. K. Mitchell W. D. Korte and W. C. Kaska Chem. Comm. 1970 1384. 258 G. Lavielle and G. Sturtz Bull. SOC.chim. France 1970 1369; E. J. Corey and J. I. Shulman J. Org. Chem. 1970,35 777. 259 H.-J. Bestmann H. Dornauer and K. Rostock Chem. Ber. 1970 103 685 2011; H.-J. Bestmann G. Graf H. Hartung S. Kolewa and E. Vilsmaier ibid. p. 2794; H.-J. Bestmann H. Scholz and E. Kranz Angew. Chem. Internar. Edn. 1970 9,796. 260 G. Eguchi K. Akiba,andN. Inamoto Bull. Chem.Soc.Japan 1970,43,438; E. Ciganek J. Org. Chem. 1970 35 3631 ;I. N. Zhmurova A. A. Tukhar' and A. V. Kirsanov Zhur. obshchei Khim. 1970,40 986. 261 G. W. Adamson and J. C. J. Bart J. Chem. SOC.(A) 1970 1452. "' A. Hassner and J. E. Galle J. Amer. Chem. SOC.,1970,92,3733.Organometallic Compounds-Part (i) The Main Group Elements N3 PPh3 H I 1 LiAIH, RI<H<H-RZ 3 N I -II R / \.-R2 R1 / \**R2 I-Scheme 18 spectra of a number of organoantimony derivatives have been The weaker proton basicity of triphenylarsine compared with both triphenyl- phosphine and triphenylstibine is attributed to electronic The bond dissociation energy D[Me,As-Me] has been estimated by a kinetic study as 63 kcal mol-1.265 Tricyclopentadienyl compounds have been characterised by spectrosopic methods and a gradation from a diene structure for (C5H=J3 As to one with greater delocalisation of double bonds for (C5H,),Bi has been suggested.266 Barriers to pyramidal inversion of more than 25 kcal mol- ’have been measured in a variety of arsenic compounds fluxional properties of cyclic arsines may be explained without postulating inversion at arsenic.267 Enantiomers of EtMePhAs and [MePhAsCH,] have been separated by crystallisation or chromatography of metal complexes.268 Exchange of alkyl groups between compounds R1 ,,R2 -,,Sb has been studied by n.m.r.269 The chemistry of arsenic ylides has been further explored :compounds stabilised by conjugation undergo normal Wittig reactions with carbonyl compounds but other ylides give mainly ep~xides.~” Reverse Wittig reactions are easier with arsenic than with phosphorus.COR’ FoR2 / Ph,AsO + R1C-CR2 -+ Ph,As=C or Ph,As=C \ \ R’ R2 The mechanism of the reactions between triphenylarsine oxide or sulphide and butyl iodide has been The reaction between R,M(M = Sb or Bi) and benzenethiol involves bimolecular homolytic substitution by PhS.at the metal.,’ 263 0. A. Gansow and B. Y. Kimura Chem. Comm. 1970 1621 T. B. Brill and G. G. Long Inorg. Chem. 1970,9 1980; G.G. Long J. G. Stevens R. J. Tullbane and L. H. Bowen J. Amer. Chem. SOC.,1970,92 4230; A. T. Rake and J. M. Miller J. Chem. SOC.(A) 1970 1881. 264 0.W. Kolling and E. A. Mawdsley Inorg. Chem. 1970,9,408. 265 S. J. W. Price and I. P. Richard Canad. J. Chem. 1970,48 3209. 266 B. Deubzer M. Elian E. 0.Fischer and H. P. Fritz Chem. Ber. 1970,103,799. 267 J. P. Casey and K. Mislow Chem. Comm. 1970,999; P. S. Elmes S. Middleton and B. 0.West Austral. J. Chem. 1970,23 1559. 26a B. Bosnich andS. B. Wild J.Amer. Chem. Soc. 1970 92 459. 269 H. A. Meinema and J. G. Noltes J. Organometallic Chem. 1970,22 653. *’’ A. W. Johnson and H. Schubert J. Org. Chem. 1970 35 2678; E. Ciganek ibid. p. 1725. 271 B. D. Chernokal’skii R. B. Bairamov and G. Kamai Zhur. obshchei Khim. 1970 40 143; B. D. Chernokal’skii A. S. Gel’fond and G. Kamai ibid. p. 151. 272 A. G. Davies and S. C. W. Hook J. Chem. SOC.(B) 1970 735.