5 Carbon Silicon Germanium Tin and Lead By D.A. ARMITAGE Department of Chemistry King's College Strand London WC2R 2LS UK This review covers the literature for 1994. The construction of carbon networks using polyynes is highlighted' with the longest chains of carbon atoms connecting two transition metals prepared to date resulting from the oxidative coupling of Cp*Re(NO)(PPh,)(C-C),-H (1 :n = 1,2) using Cu(OAc) to give Cp*Re(NO)(PPh,)C,(NO)(PPh,)ReCp*,(n = 4,6,8). The chirality at Re and two closely spaced sets of resonances in the NMR spectra support the presence of meso and ( & ) diastereoisomers. The UV maxima shift to longer wavelengths with increasing chain length and the cation radicals become less stable with increasing n.' The lithium derivative of (1 :n = 2) adds to the CO of ~S-Cl,C,Mn(CO)3 to ultimately form the cation (2) in which a five carbon cumulene unit connects the two Re atoms (Equation 1).The cumulene form appears to dominate over the polyyne form since the Re-C stretching frequency is at ca. 1700cm-' compared with that of 1653-1630cm-' for Re-C-C. The first isolable pentatetraenylidene complex (3) has been formed from the reaction of (Ph,PCH2CH2PPh,),RuC12 and HC-C-C-C-CPh,OSiMe (Equation 2) and has C=C bond lengths of 125 130 124 and 136pm therefore indicating some triple-single alternation superimposed on what are essentially double bonds.4 Noble metal carbonyl cations are highlighted5 and the two complexes [Ag(CO),] '[B(OTeF,),]-(n = 1,2) have been isolated and characterized under an atmosphere of CO.The carbonyl stretching frequencies of 2204cm-' (n = 1) and 2196cm-' (n= 2) and a long Ag-C bond indicate little back-donation. The C-0 bond distances of 107-109 pm are distinctly shorter than in gaseous CO (1 12.8 pm) and it is suggested that coordination may occur with an orbitaI of antibonding character that coordina- tion increases s-character in the C-0 bond and that coordination to an electrophilic site strengthens the C-0 bond.' It has been shown that the 1:2 anionic Pd complexes resulting from sulfur and seleno derivatives of 1,3-dithiole-2-thionate C3Sz -and C,S,Sei -(L) can be readily oxidized to (Me,N)+(PdL,)-. The anions occur as dimers with Pd-Pd distances of U.H. F. Bunz Angew. Chem. Int. Ed. Engl. 1994 33 1073.' M. Brady W. Weng and J.A. Gladysz J. Chem. SOC.,Chem. Commun. 1994 2655. W. Weng T. Bartik and J.A. Gladysz Angew. Chem. Int. Ed. Engl. 1994 33 2199. D. Touchard P. Haquette A. Daridor L. Toupet and P.H. Dixneuf J. Am. Chem. SOC.,1994,116,ll 157. L. Weber Angew. Chem. Int. Ed. Engl. 1994 33 1077. P.K. Hurlburt,J. L. Rack J. S. Luck S. F. Dec J. D. Webb 0.P. Anderson and S. H. Strauss J. Am. Chem. Soc. 1994 116 10003. 53 D.A. Armitage ON 9".PPh3 ON'??-PPh, C fi Ill c C -fi q5-C15C5Mn(C0)3 5 BF3 Cp*Re(NO)(PPh3)C4Li E Me30*BF4-L2RuCh + H(CZC)2-CPh20SiMe3 (' Et3N* [L~(CI)RU=C=C=C=C=CP~-JPF~-(2) (ii) Ph3C*PF6-(L = PhZPCH2CH2PPh2) (3) 317-318 pm. The conductivity of these complexes increases with pressure but decreases at low temperat~re.~ The metallocarbohedrene v&,+,has been shown to react with oxygen to give V,C:o and CO.It is much more reactive than Ti,C12 which has a nearly closed shell electronic structure.8 Further structural work on the paramagnetic anions M:-(M = Ge Pb) (21 skeletal-electrons) has shown that they possess the tricapped trigonal prism structure expected for 20 skeletal-electron systems rather than the monocapped quadratic antiprism found for 22 skeletal-electrons. The tin derivative possesses D, symmetry whilst the germanium and lead ones are distorted to C2v.9Previous work supports these conclusions." By way of contrast the phase Na,Sn contains isolated tin atoms (inter-tin distance 554pm) and reacts with both red and white phosphorus to give Na,P and Sni- while with NbCl, water-stable Nb,Sn results.' ' Cleaving one Si-Si bond of (Ar2Si)3 (Ar = 2-Me,NCH2C,H,) with Li in 1,4- dioxane gives the trisilane dianion Li(Ar,Si),Li which gives two 29Si NMR signals at -26.5 and -31.8.Dioxane and the amino groups coordinate to Li and Li-Si bonds of 254.3 pm are the shortest reported to date. Steric crowding lengthens the Si-Si bonds to 240.4 pm while the Si-Si-Si angle is 136.9'. Li(Ar,Si),Li results from the reaction with excess lithium and is the first vicinal dilithiodisilane. The structure indicates two ' C. Faulmann J.-P. Legros P. Cassoux J. Cornelissen L. Brossard M. Inokuchi H. Tajima and M. Tokumoto J. Chem. SOC. Dalton Trans. 1994 249. * C.S. Yeh S. Afzaal S.A. Lee Y.G. Byun and B.S.Freiser J. Am. Chem. SOC. 1994 116 8806. T. F. Fassler and M. Hunziker Znorg. Chem. 1994 33 5380. lo S. C. Critchlow and J. D. Corbett J.Am. Chem. SOC.,1983,105,5715; C. Belin H. Mercier and V. Angilella New. J. Chem. 1991,15 931. F. Guerin and D. Richeson J. Chem. SOC.,Chem. Commun. 1994 2213. Carbon Silicon Germanium Tin and Lead independent molecules with Si-Si bonds of about 238 pm and Si-Li bonds of about 255 and 259 pm." The first reported synthesis of disilagermirane (Me,Si),Ge[Si(SiMe,),1, has resulted from the reaction of (Me,Si),SiLi(THF) and GeCl,. The exocyclic Ge-Si bonds of 235.6 pm are shorter than the endocylic distances of 239.1 pm and a similar shortening is also observed with the Si-Si bonds. Reacting (Me,Si),Ge with MeLi in the presence of 12-crown-4 gives [Li( 12-crown-4)J +[Ge(SiMe,),] -with Si-Ge bonds of 236.6 and 236.9pm and bond angles of 100.5 to 102.7".13 The thermolysis of mes,SiGe or mes,Ge with 2,3-dimethylbutadiene has been shown to give the germacyclopentenes (4) and (5).It is thought that germylene addition may occur with (5) giving germasilene or digermene rearrangement the appropriate silyl or germyl germylene (Equation 3). l4 (4) (5)(M = Si Ge) rnes2M=Gemes2 -mes,M(mes)Ge (3) (M = Si Ge) Photolysis of (BukSi) in the presence of alkenes and dienes has been shown to result in disilene and silyene addition to the double bond to give the silirane and 1,2-disilacyclobutane respectively (Equation 4) while with conjugated dienes the 2-vinylsilirane is formed.' H 77 + Bu,'Si + A k'R H-C-C-R !' But2Si-/\ CH2 But2Si-SiBut2 (4) With the bis(alky1idene)disilacyclobutane (6) photolysis in the presence of C, gives the 1 1adduct through addition to the C-C bonds common to two adjacent hexagons.Subsequent rearrangement leads to the 2,6-disilabicyclo[4.2.O]oct-1-ene derivative (7) (Equation 5).16 Photolysis of C, and the disilirane (8) results in addition only at the equatorial C-C bonds without rearrangement to give the 1,3-disila substituted cyclopentane (9) (Equation The disilene silicon atoms of fully silylated disilenes have been found to show significant downfield shifts from unsilylated derivatives. Also dissolution of the l2 J. Belzner U. Dehnert and D. Stalke Angew.Chem. Int. Ed. Engl. 1994 33 2450. l3 A. Heine and D. Stalke Angew. Chem. Int. Ed. Engl. 1994 33 113. l4 K. M. Baines J. A. Cooke C. E. Dixon H. W. Liu and M. R. Netherton Organometallics 1994 13 631. l5 M. Weidenbruck E. Kroke H. Marsmann S. Pohl and W. Saak J. Chem. Soc. Chem. Commun. 1994 1233. l6 T. Kusukawa Y. Kabe T. Erata B. Nestler and W. Ando Organometallics 1994 13 4186. l7 T. Akasaka E. Mitsuhida W. Ando K. Kobayashi and S. Nagase J. Am. Chem. SOC.,1994 116,2627. D.A. Armitage disilenes in hexane produces a colour change (R,Si = PriSi) from yellow to red indicating conformational changes due to the relief of steric strain.18 The hindered diplumbane TsiMe,PbPbMe,Tsi has the longest PbPb bond reported to date (296.8 pm) shows considerable tetrahedral distortion at lead is orange-yellow in colour and dissociates photochemically to give plumbyl radicals through PbPb cleavage.' Cleavage of the bridging Si-Si bond of decaisopropylbicyclo[2.2.0]hexasilane using PdCl,(PhCN) has been shown to give both cis-and trans-1,4-dichlorocyclo-hexasilanes.Their structures indicate a sterically distorted chair conformation while reduction with sodium reforms the bicylco[2.2.0]hexasilane quantitatively.20 The ladder polysilane (1 0) results from all-transCBu'ClSi] and C1-PriSiSiPriCl using Li. The Si-Si bond lengths vary from 241.2 to 248.1 pm.21 Cage-opening of octakis( 1,1,2- trimethylpropyl)octasilacubane using PCI gives a mixture of the endo,exo- exo,exo- and endo,endo-isomers of 4,s-dichloroocta- kis(l,1,2-trimethylpropyl)tetracyclo[3.3.O.O2~7.O3~6] -octasilane (1 la and 1 lb), (note the structural rearrangement on cleavage of the one Si-Si bond).Activation of silane by tungsten cations in the gas-phase has been found to result in M. Kira T. Maruyama C. Kabuto K. Ebata,and H. Sakurai Angew. Chem. Int. Ed. Engl. 1994,33 1489. l9 S. M. Whittaker F. Cervantes-Lee and K. H. Pannell Inorg. Chem. 1994 33 6406. *' S.Kyushin H. Yamaguchi T. Okayasu Y. Yagihashi H. Matsumoto and M. Goto Chem.Lett. 1994,221. S. Kyushin M. Kawabata Y. Yagihashi H. Matsumoto and M. Goto Chern. Lett. 1994 997. 22 M. Unno K. Higuchi M. Ida H. Shioyama S. Kyushin and H. Matsumoto Organometallics 1994 13 4633. Carbon Silicon Germanium Tin and Lead 57 dehydrogenation and the formation of cluster species such as WSi,,H (x= 4,6).’ Reacting sodium or potassium with silane in diglyme gives the polysilylated silyl anion Mf[SiH3 -,,(SiH,),,] -which itself can be methylated or silylated using p-tolylS0,Me or C,F,SO ,SiH,.Similarly the silylated germane stannane or phosphine result if GeH, SnH, or PH are reacted with silane. Neopentasilane (H,Si),Si has Si-Si bond lengths of 233.2 Also sodium has been shown to cleave the terminal C-0 bond of diglyme to yield the silanide Na,(OC2H,0C,H,Me),(SiH,),. The Na cube is face-capped by alkoxide ions with the two silanide anions bonding to opposite sodium ions remarkably through bridging hydrogen atoms from the H,Si-group and not through silicon coordination. Calculations show this inverted coordination to be energetically the more favo~rable.~~ The gas-phase structure of H,Si-GeH has been shown to comprise Si-H and Ge-H bonds of 149.4 and 153.8pm respectively while the Si-Ge bond length of 236.4pm was found to be shorter than calculated.26 2,6-bis(Dimethylaminomethyl)phenyl-lithium(LLi)reacts with its 1-silylderivative to give the [4 + 41-coordinated silicon species (12).The H-Si-H angle is about 115” with an Si-N bond length trans to Si-H of 311.7pm and those trans to Si-C of 289.5pm. The amino groups are equivalent on the NMR time-scale. With Ph,C+BF or iodine (12)is deprotonated to give the five-coordinate monocation (13)with one of the substituted aryl groups non-coordinating. With HCl or HBr hydrogen is evolved to give the six-coordinate cation (14) (Scheme l).27 LLi + LSiH3 -1 2 ph37 (12) 0.512 1.1 I /N\ Scheme I The six-coordinate bis[8-dimethylaminonaphthyl]dihydrosilane (15) has been deprotonated with iodine to give the five-coordinate cation stabilized by the centrosymmetric 1;-anion.This cation has apical Si-N bonds of 207 pm shorter than 23 A. Ferhati T. B. McMahon and G. Ohanessian Bull. SOC. Chim. Fr. 1993 130 3. 24 T. Lobreyer W. Sundermeyer and H. Oberhamrner Chem. Ber. 1994 127 2111. 25 H. Pritzkow T. Lobreyer,W. Sundermeyer,N. J. R. van Eikema Hommes and P. von R. Schleyer,Angew. Chem. Int. Ed. Engl. 1994 33 216. 26 H. Oberhamrner T. Lobreyer and W. Sundermeyer J. Mol. Struct. 1994 323 125. ” F. Carre C. Chuit R. J.P.Corriu A. Mehdi and C. Reye Angew. Chem. Int. Ed. En& 1994,33 1097. @$+ 58 D. A. Armitage in (19,and with 8-(dimethylamino)naphthyl-lithium(L'Li) gives the seven-coordinate silane (16) (Equation 7).,* 1' QIMe2 1 LSiH2 Si-H 2 b2-(15) The first silylene complex of nickel (18) has been found to result from the stable silylene (17) and Ni(CO) (Equation 8). It is highly air- and moisture-sensitive but thermally stable [m.p. 160 "C (decomp.)] and shows approximate tetrahedral coor- dination at Ni. The Ni-Si bond lengths are ca. 221 pm and the carbonyl stretching frequencies similar to those found in (Ph,P),Ni(C0),.29 (17) (18) Photolysing Fe(CO) with (Me,N),SiH gives the silylene complex stabilized by coordinated Me,NH.Reaction with Pt(C,H,)(PR,) (19) results in displacement of both Me,NH and C2H4 to give the silylene derivative n-complexed to Pt (20) (Equation 9). (C0)4 hvlhexane YMe2 (19) p Fe(CO) + HSi(NMe,) 7(C0)4Fe=Si(NMe2)2 -i -Pf(PR3)Z (9) ,Si Me2N NMe2 The reaction of (EtO),PFe(CO) results in EtO/Me,N exchange between the phosphite and aminosilane to give [(Me,N),P(OEt)](CO),Fe=Si[( + NHMe,)-(OEt),(NMe,)] which crystallizes as a dimer through hydrogen-bonding of the coordinated amine to the ethoxy group on the silicon of the neighbouring molecule.30 Silylene complexes of transition metals have been prepared with groups at silicon capable of n-stabilization. With the ruthenium derivatives Cp*(Me,P),Ru-Si(S-p- + tolyl) and [Cp*(Me,P),Ru=Si(SEt),] BPhi exchange of thio groups occurs 28 C.Breliere F. Carre R. Corriu and M. W.C. Man J. Chem. Soc. Chem. Commun. 1994 2333. l9 M. Denk R. K. Hayashi and R. West J. Chem. SOC.,Chem. Commun. 1994 33. 30 U. Bodensieck P. Braunstein W. Deck T. Faure M. Knorr and C. Stern Angew. Chem. Int. Ed. Engl. 1994 33 2440. Carbon Silicon Germanium Tin and Lead 59 between Si sites.,' The triflates Cp*(Me,P),Ru-SiR,OTf (R = Me Ph) have been shown to react with LiB(C,F,) to give the stable silylene complexes base-free and without x-donor stabilization. The methyl derivative [Cp*(Me,P),Ru=SiMe,] + [B(C,F5),] -has a Ru=Si bond length of 223.8 pm the shortest reported to date., The silylene (17) has been shown to react with Me,SiN3 to give the silanimine which adds further azide.With the hindered Ph,CN, however the silanimine (21) can be isolated as a THF complex with a Si=N bond similar in length to that reported in Me,Si(THF)=NSiBu\ (Equation BU' The germylene (22) reacts with Me,Si(N,) to give the germanimine (23) (Ge=N 170.4 pm) which rearranges to the silanimine. This subsequently dimerizes or hydrolyses to the silatetrazole (24) (Scheme 2).34 With R2Si(N3)2 (R = But mes) 2 moles of (22) gave the bis(germanimine) R,Si(N=GeDis,),. For R = mes the Ge=N bond length is 168.1 pm and the Si-N bond 171.7pm supporting a germanimine structure. For R = But the germanimine rearranges photolytically probably through C-H insertion and butene elimination to give the cyclic silanimine (25) (Equation 11).35 Dis2Ge + Me2Si(N3)2-Me2Si-N=GeDis,/I;@-Me2Si=N-GeDis, I I N3 (23) (22) Dis = CH(SiMe,) Y3 ,GeDis2 OH Me2 1 Me2 Si Me2Si-N I1 Dis2Ge-HNSiN,' NGeDis2 N-SiMe2 N=N'IN~ Dis2Ge' N3 (24) Scheme 2 Matrix isolation spectroscopy involving the decomposition of silyl azide has provided proof of the formation of silane nitrile H-Si-N and silane imine H,Si=NH together with hydrogen loss.The dissociation enthalpy of H3N -+ SiH is estimated to be 97 & lOkJrn01-'.~~ 31 S.K. Grumbine and T.D. Tilley J. Am. Chem. Soc. 1994 116 6951. 32 S.K. Grumbine and T. D. Tilley J. Am. Chem. Soc. 1994 116 5495. 33 M. Denk R. K. Hayashi and R. West J. Am. Chem. Soc. 1994 116 10813. 34 T. Ohtaki and W. Ando Chem. Lett. 1994 1061. 35 W. Ando T. Ohtaki and Y.Kabe Organometallics 1994 13 434. 36 G. Maier and J. Glatthaar Angew. Chem. Int. Ed. Engl. 1994,33,473; R.T. Conlin D. Laakso and P. Marshall Organometallics 1994 13 838. D.A. Armitage But hv>monrn HN Ge. -2(22) + ButzSi(N,) -R,Si(N=GeDis,) ,Si=N ,Dis (11) I Dis,Ge LSiA:iMe3 Me (25) An NMR study of lithium hexamethyldisilazide with THF and ether in toluene and pentane shows that ligand exchange in the disolvated dimers proceeds by a dissociative process via monosolvated dimer~.,~ A similar study using LiN(SiMe,),/KN(SiMe,) mixtures suggests a statistical mixture of the dimers in THF but no mixed derivative in TMEDA. * The lithium dimer complexes with fluorobenzene and o-difluorobenzene to give 1 1 adducts with Li-F bond lengths of 186.6 and 189.4pm.With 1,4- difluorobenzene a linear polymer results with a Li-F bond length of 199.9 pm. In all cases the Li,N ring is maintained without Si-F cleavage.39 A range of silylated lithium amides has been structurally characterized. The tripodal amide MeC{CH,N(Li[LJ)SiMe,) (L = THF HMPTA) possesses a six-membered Li,N ring with a chair conformation which is solvated at each lithium atom.40 The compounds (Me,Si),NSi(H)(NLiSiMe,) and Me,Si(NLiSiMe,) occur as dimers in both solid and solution while lithiated derivatives of (Me,SiNH),SiH give mono- di- and tri-lithio species in solution. The tri-lithio derivative is dimeric in the solid with two interconnected SiN,Li rings.41 The hydrazine (Me,Si),N,Li is also dimeric with a chair-like N,Li ring (26) with Li-Li 228 pm N-Si 171-177 pm and N-N bonds of 150.9 pm.The compound Bu'Me,SiN(Li)-N(Li)SiMe,Bu' is a trimer which comprises two-chair Li,N rings with alternating Li and N atoms. These chairs are joined through the N-N bonds and various Li-N interactions; structure (27) represents the monomer unit.42 The thallium amide (Me,Si),NTl was shown to be monomeric in benzene and the gaseous-state but occurs as cyclic dimers in the solid-state interconnected to give infinite chains through interdimer TI-T1 contacts of 395pm some 30 pm longer than the intradimer Tl-Tl contacts.43 The silyl substituted arylamine derivative (2,6- Pr;C,H,(Me,Si)NTl) is tetrameric in the solid state with aryl groups giving $-coordination to the T1 of the neighbouring molecule and weak Tl-.Tl interactions at 406pm .44 37 B.L. Lucht and D. B. Collum J. Am. Chem. Soc. 1994 116 6009. 38 M. A. Nichols D. Waldmuller and P.G. Williard J. Am. Chem. Soc. 1994 116 1153. 39 P.G. Williard and Q.-Y. Liu J. Org. Chem. 1994 59 1596. 40 K. W. Hellmann L.H. Gade W.-S. Li and M.McPartlin Inorg. Chem. 1994 33 5974. 41 M. Veith M. Zimmer and P. Kosse Chem. Bet-. 1994,127,2099;P. Kosse E. Popowski M. Veith and V. Huch ihid. 2103. 42 N. Metzler H. Noth and H. Sachdev Angew. Chem. Int. Ed. Engl. 1994 33 1746. 43 K. W. Klinkhammer and S. Henkel 1.Organomet. Chem. 1994 480 167. 44 S.D. Waezsada T. Belgardt M. Noltemeyer and H.W. Roesky Angew. Chem. Int. Ed. Engl. 1994 33 1351. Carbon Silicon Germanium Tin and Lead 61 The silatrane ClSi(HNCH,CH,),N has been pentafluorophenylated at Si using C,F,Li but with ClSi(MeNCH,CH,),N the fluoro derivative is formed with a Si-F bond length of 164.3 pm and Si-N interaction of 203.4 pm.The pentafluorophenyl derivative is also formed which itself gives the product formed through tetrafluoroben- zyne insertion into one Si-NMe bond.45 The disilylphosphide anion of [(H,Si),P] -[Li(TMEDA),] shows a Si-P bond + length of 217 pm and an angle at phosphorus of 92.3'. With the magnesium derivative [(Me,Si) P] ,MgDME which results from [(Me,Si),N] Mg and (Me,Si),PH the Si-P-Si angle was found to be 106.6' and the Si-P bond length about 222~m.~~ Condensing Bu'SiFCl with CyPHLi gives the fluoro-substituted cyclosilaphos- phane (28) which with further CyPHLi forms the propellane-like silacyclophosphane (29) (Equation 12) in which the Si-P bond lengths are from 226 to 229 pm.The Si-.Si distance of 251.8 pm is within the range of single bonds but calculations support a Si-Si bond order of -0.260 or antib~nding.~~ Even shorter 'non-bonded' interactions are found in cyclodisiloxanes. CY CyPHLi Bu'SiFCh -Bu'FSi,/p\/SiFBu' -(12) P CY But Condensing TipBu'SiCl (Tip = 2,4,6-Pr',C6H,) with LiAsH,DME gives the first reported diarsanylsilane (30) which on lithiation and coupling with mesBu'GeF, gives the 1,3-diarsa-2-sila-4-germacyclobutane (31) and subsequently the Bu'/Bu' exo-endo bicycloCl.1 .O]butane derivative (32) as the only isomer on mercury substitution and photolysis.The compound (31) has Si-As bond lengths of 239-240 pm and Ge-As bonds of about 245.5pm (Equation 13).48 The stannaphosphene Tip,Sn-Pmes* (mes* = 2,4,6-Bu',C6H,) adds to various But J" 45 Y. Wan and J. G. Verkade. Organometallics 1994 13 4164. 46 G. Becker B. Eschbach D. Kashammer and 0. Mundt Z. Anory. Ally. Chem. 1994 620 29; M. Westerhausen and W. Schwarz ibid. 304. 47 M. Driess R.Gleiter R.Janoschek H. Pritzkow and M. Reisgys Angew. Chem. Int. Ed. Engl. 1994,33. 1484. 48 M. Dreiss and H. Pritzkow Chem. Ber. 1994 127 477. 62 D. A. Armitage a-ethylene aldehydes and ketones to give the six-membered ring stannoxaphos- phorinenes through [2 + 41 cycloaddition (Equation 14).49 0+ QCH2 Tip2Sn=Pmes* i G-C (14) R’ R2 The greater acidity of silanols compared with alcohols has long been recognized but their Bronsted basicity has been little studied.Treating Bu‘,Si+[Br,CB ,H,] -with undried solvents gives the hydrated cation- or protonated silanol[Bu’,SiOH,] . The + structure reveals hydrogen bonding between water and two bromine atoms of the anion trigonal flattening at silicon with a C-Si-C bond angle of 116” and a long Si-0 bond of 177.9pm.” Procedures have been outlined for the preparation from chlorosilanes of silanols and silane diols prone to self-conden~ation,~ while (PhCH,),SiOH (PhCH,),COH and (PhCH,),SiH are isomorphous with threefold symmetry.’ Ph,Si(OH) and Cp,MMe (M = Zr Hf) yield the eight-membered ring [Cp2M(,u- OSiPh,O)] while metallasiloxanes containing Ta Nb Mo W Re Mn and Mo have been prepared from the diols Bu\Si(OH), O(Bu‘,SiOH), and O(Ph,SiOH),.A similar oxovanadyl(1v) derivative has also been made from O(SiPh,OLi) .2THF and VCl,.’ Condensing RSi(OH) (R = 2,6-Pr\C,H3NSiMe,) with Bu\AlH furnishes the ahminosilicate frameworks Al,Si,O and A1,Si2O, and with Ti(OPr’) the Si4Ti408 framework.’ (c-C,H,Si),O,(OH) condenses with M[N(SiMe,),] (M = Y Nd) to give associated derivatives that form dimers upon coordination with Ph,PO.’ (c-C,H ,Si),O,(OH) has been capped with the Ph,C,Ti residue through reaction with (Ph,C,),TiCl in the presence of base.’ (c-C,H lSi),O comprises two non-planar Si,O rings joined cofacially by three Si-0-Si bridges to build a framework with Si40 ringss7 The structures of several cyclodisiloxanes with mesityl and adamantyl substituents show Si-0 bonds of 167-168 pm and Si-Si cross-ring interactions of about 239 ~m.’~ Me,NLi ring-opens (Me,SiO) to give the hexameric [LiOSiMe,(NMe,)] as a hexagonal barrel of alternate Li and 0 atoms with silylamino groups coordinated to each lithium atom., Amorphous silica with oxalic acid in the presence of tertiary 49 A.Kandri-Rodi H. Ranaivonjatovo and J. Escudie Organometallics 1994 13 2787. 50 Z. Xie R. Bau and C.A. Reed J. Chem. SOC. Chem. Commun. 1994 2519. 51 J. A. Cella and J.C. Carpenter J. Organomet. Chem. 1994 480 23. 52 P. Lightfoot C. Glidewell and P.G. Bruce J. Organomet. Chem. 1994 466 51; C. Glidewell and P. Lightfoot ibid. 1994 484,175. 53 E.Samuel J. F. Harrod M. J. McGlinchey C. Cabestaing and F. Robert Znorg. Chem. 1994,33 1292; H.-J. Gosink H. W. Roesky H.-G. Schmidt M. Noltemeyer E. Inner and R. Herbst-Irmer Organometal-lies 1994 13 3420; M. Motevalli D. Shah S. A. A. Shah and A.C. Sullivan ibid. 4109. 54 M. L. Montero I. Uson and H. W. Roesky Angew. Chem. Znt. Ed. Engl. 1994,33,2103;N. Winkhofer A. Voigt H. Dorn H. W. Roesky A. Steiner D. Stalke and A. Reller ibid. 1352. 55 W. A. Herrmann R. Anwander V. Dufaud and W. Scherer Angew. Chem. Int. Ed. Engl. 1994,33,1285. 56 L.D. Field C. M. Lindall T. Maschmeyer and A.F. Masters Aust. J. Chem. 1994 47 1127. 57 H. Behbehani B. J. Brisdon M. F. Mahon and K.C. Molloy J. Organomet. Chem. 1994 469 19. 58 H. Sohn R.P. Tan D. R. Powell and R. West Organometallics 1994 13 1390.59 G. E. Herberich T.P. Spaniol and A. Fischer Chem. Ber. 1994 127 1619. Carbon Silicon Germanium Tin and Lead 63 amine and 18-crown-6 gives the soluble (R,NH+),Si(oxalate)~- in high yield providing another example of the solubilization of silica.,' The reaction of GeCl with the potassium derivative of catechol has been shown to give K2[Ge(cat),].3H,O.2EtOH as a hydrated network connected through hydrogen bonds and chains cross-linked by K-aryl 'zipper' interactions.,' Oxidizing the stannylene [2,4,6-(F,C),C6H,],Sn results in the formation of the monomeric planar cyclotristannoxane with a Sn-0-Sn angle of 135.5' and an Sn-0 bond length of 193.1 pm.62 A redetermination of the structure of lead tetraacetate shows it to be near dodecahedra1 with each acetate bidentate and Pb-0 bond lengths ranging from 224.4 to 23 1.2 The precipitate resulting from mixing cyclodextrin with lead@) nitrate shows 16 lead(I1) atoms incorporated into the cyclodextrin torus with the lone pair of electrons on lead stereo-active and the coordination around lead being composed of a square pyramid of four Pb-0 bonds., The silene Me,Si(mes)Si=C(OSiMe,)Ad adds both sulfur and selenium to give the silathiirane and silaselenirane.The former shows a Si-S bond length of 212.9 pm.65 The reaction of Tbt(Tip)SiBr with LiNaph then sulfur gives the five-membered heterocycle (33) which with Ph3P gives the silanethione (34) as yellow crystals m.p. 185-189 "C and Si-S stretching frequency of 724cm-' (Equation 15).The structure supports trigonal planar geometry at Si with an Si-S bond length of 194.8 pm some 9% shorter than a single bond and it adds to dienes mesCNO and PhNCS.66 Tbt \ (i) LiNaph Tbt \ fS-s 3Ph3P Tbt\ ,SiBr2 -,S\ I -Si=S RP (ii) sulfur Tip s's 3Ph3P=S Tip' (Tbt = 2,4 6-[(Me3Si),CHI3C6H2) The germaneselenone Tbt(mes)Ge=Se can be prepared similarly has a bond length of 218.0 pm and a stretching frequency of 382 cm-' (cf.germanethione at 521 cm- '). It reversibly adds [4 + 21 to dienes [3 + 21 to mesCNO and [2 + 21 to PhNCS.67 The macrocyclic octamethyldibenzotetraaza[ 14lannulene dianion [Me8taa12-furnishes a Sn" derivative with SnCl which adds both sulfur and selenium. The tin atom lies above the tetra-nitrogen plane with Sn-N bond lengths shorter in the oxidized chalcogen derivatives.The Sn-S and Sn-Se bond lengths are 227.4 and 239.4 pm respectively.68 Heating SnS with Rb,CO at 190 "C in the presence of H2Shas been shown to give Rb2Sn,S,.2H,O which comprises both SnS tetrahedra and SnS octahedra. The 6o K. E. Bessler and V. M. Deflon 2.Anorg. Allg. Chem. 1994,620,947. 61 J. Parr A. M. Z. Slawin J. D. Woollins and D. J. Williams Polyhedron 1994 13 3261. 62 J. F. van der Maelen Uria M. Belay F.T. Edelmann and G. M. Sheldrick Acta Crystallogr. Sect. C,1994 50,403. 63 M. Schurmann and F. Huber Acta Crystallogr. Sect. C 1994 50 1710. 64 P. Klufers and J. Schuhmacher Angew. Chem. Int. Ed. Engl. 1994 33 1863. 65 A.G. Brook R. Kumarathasan and A. J. Lough Organometallics 1994 13 424.66 H. Suzuki N. Tokitoh S. Nagase and R. Okazaki J. Am. Chern. Soc. 1994 116 11 578. 67 T. Matsumoto N. Tokitoh and R. Okazaki Angew. Chem. Int. Ed. Engl. 1994,33 2316. 68 M.C. Kuchta and G. Parkin J. Am. Chem. SOC. 1994 116 8372. D. A. Armitage reaction of SnCl and selenium with Rb,CO produces Rb,Sn,Se which contains SnSe tetrahedra and exhibits bond lengths of 246~m.~~ Fluorinating (BrMe,Si),C with SbF gives the fluoro derivative (35) which has a Catherine wheel-like structure. The c6 ring is slightly distorted to a boat structure and each Si-F bond (168pm) is longer than that for normal four- and five-coordination with the bridge bonds (239 pm) being shorter than normally found for the minimum non-bonded approach (263pm). The F-Si-F angles lie in the range 172-179" (Equation 16).At 0 "C the 29Si NMR spectrum shows the expected 1 :2 1triplet which does not change to a doublet of doublets on cooling but gives a septet at 55 "C. The 'H and I3C NMR spectra behave similarly. The septet indicates equal interactions of the Si H and C nuclei with all six fluorine atoms suggesting free rotation of the silyl groups in a cog-wheel fashion so that the fluorine atoms are transferred around the ring. This process is stopped when the ring is n-bonded to the bulky Mo(CO) residue the 29Si NMR spectrum showing only a triplet between 25 "C and 95 "C. The methoxy derivative with Si-0 bonds of 188pm has D, symmetry and gives high field 29Si NMR shifts of -64.2 ppm typical of five-c~ordination.~' F-si.-..F SbF /S@'S; 'F -(FMe,Si),C,Mo(CO) (16) Mo(C0)6 (BrMe2Si)& -Fa..Si Si \ F.....Si-F (35) Iodosilanes R,SiI have been conveniently prepared from R,SiH and Me1 using PdCl as catalyst. Yields are excellent. Et,SiI is also produced in good yields from Et,SiH and PrT7 Under microwave conditions alkyl and aryl halogermanes R,GeX,- (R = Et Bu Ph; X = C1 Br) result in good yields from the redistribution of R,Ge with GeX in a matter of minutes.72 Hydrolysis of SnF in concentrated aqueous solution gives the oxyfluoride Sn,OF,. It crystallizes with a 3D structure with both F and 0 bridges.73 The salt (NH;),Me,SnFZ-crystallizes with a hydrogen bonded network and the centrosym- metric anion has Sn-F bond lengths of 212.7 pm. The compound Et,N+Ph,SnCI has been shown to contain an anion that is trigonal bipyramidal with phenyl groups equatorial and the Sn-Cl bond lengths of 237.8 pm (equatorial) and 251.7 to 253.1 pm Stannic chloride gives a 3 :2 complex with [9]-aneS (1,4,7-trithiacyclononane) which comprises [SnC1,[9]-aneS3] + cations and SnC1;- anions in the ratio 2 :1.In the cation the thiacrown is facially coordinated while the Sn-C1 bond length of 236.9 pm is shorter than that in the octahedral anion (244.8 pm). With [18]-aneS in MeCN the adduct 2SnC1,.[18]-aneS6.MeCN results in which the thiacrown cis-chelates to SnCl h9 W.S. Sheldrick and B. Schaaf Z. Anorg. Allg. Chem. 1994 620 1041. 70 K. Ebata T. Inada C. Kabuto and H. Sakurai J. Am. Chem. Soc. 1994 116 3595. 11 A. Kunai T.Sakurai E. Toyoda M. Ishikawa and Y. Yamamoto Organometallics 1994 13 3233. 72 R. Laurent A. Laporterie J. Dubac and J. Berlan Organometallics 1994 13 2493. i3 I. Abrahams S. J. Clark,J. D. Donaldson Z. I. Khan and J. T. Southern J.Chem.Soc.,Dalton Trans. 1994 2581. 74 D. Tudela J. Organomet. Chem. 1994,471 63; E. Garcia Martinez A. Sanchez Gonzalez A. Castineiras J. S. Casas and J. Sordo ibzd. 1994 469 41. Carbon Silicon Germanium Tin and Lead molecules at opposite ends of the ring.75 The structure of MeSnC1 shows the tin to be six-coordinate with two of the three chlorine atoms involved in bridging. The non-bridging Sn-Cl bond (228.3 pm) is 3.5 pm shorter than the two bridging Sn-C1 bonds with weak bridge bonds of 371.4~m.~~ Reacting Me -flSnClfl+ (n = 0-2) with water in the presence of 1,3-xylyl-18-crown-5 results in coordination of the water rather than hydrolysis.Crown.MeSnC1,.2H20 has six-coordination at tin with the three chlorine atoms mutually cis and the crown ether held through hydrogen bonding to the two water molecules. C2-n-butyl- 1,3-xylyl- 18-crown-5].Me2SnC12.H20 shows tin to be five-coordinate with water axial and hydrogen bonded to the crown ether.77 75 G.R. Willey A. Jarvis J. Palin and W. Errington J. Chem. SOC.,Dalton Trans. 1994 255. l6 W. Frank G.J. Reiss and D. Kuhn Acta Crystallogr. Sect. C 1994 50 1904. ” S. E. Johnson and C. B. Knobler Organornetallics 1994 13 4928.