5 C,Si Ge Sn Pb; N P As Sb Bi By P. G. HARRISON Department of Chemistry University of Nottingham University Park Nottingham NG72RD 1 General A new electronegativity scale for the elements of Group IV has been estimated from the observed bond distances in the bivalent and tetravalent halides. Predicted values are C 2.6; Si 1.9; Ge 2.5; and Sn 2.3.' 2 Carbon Studies of the reaction of atomic carbon with both water2 and ammonia3 have appeared. In the former study the results of experimental and theoretical investiga- tions were compared. The theoretical study involved both 'Dand 3P states of carbon. For C ('0)atoms the process having the lowest activation enthalpy is cleavage of an initially formed carbon-water complex to CO and H2 along a closed-shell surface (AH*= 5.2 kcal mol-').Rearrangement of the closed-shell car- bon-water complex to hydroxymethylene has AHS = 11.6 kcal mol-'. For the triplet carbon atoms the most favourable reaction of the initial carbon-water complex was simply dissociation to C + H20. The enthalpy for rearrangement of the C(3P)-H20 complex to hydroxymethylene was 22.8 kcal mol-'. The barriers to rearrangement of singlet and triplet hydroxymethylene to formaldehyde were similar (38.9 and 41.3 kcal mol-' ). Experimental data confirmed the general theoretical predictions with atomic carbon generated from the thermolysis of 5-diazotetrazole reacting with water to give carbon monoxide (9.5%) and formaldehyde (2.4%) whilst addition of oxygen a scavenger of triplet carbon atoms increases the CO yield to 53.7% leaving the yield of formaldehyde unchanged.The reaction with oxygen alone produces only CO (47%). In the reaction with ammonia arc-generated atomic carbon affords methylenearnine H2C=NH by insertion into the N-H bond which further produces HCN. The second principal mode of reaction is hydrogen abstrac- tion yielding CH2 which reacts with NH3 to produce methylamine. Hydrolysis of the non-volatile residue from the reaction produces the amino-acids glycine alanine N-methylglycine and aspartic acid. Serine is also formed when water is included with the reactants. Hydrogen cyanide polymer is not a major precursor for amino-acid formation. The detailed reaction pathway for the hydration of ketenimine CH,=C=NH by H20 and (H20)2 has been investigated by ab initio methods.The preferred reaction pathway is with the water dimer through a 'pre-association' ' I. Hargittai and C. Bliefert Z. Nuturforsch. Ted B,1983 38,1304. ' S. N. Ahmed M. L. McKee and P. B. Shevlin J. Am. Chem. Soc. 1983 105 3942. P. B. Shevlin D. W.McPherson and P. Melius J. Am. Chem. SOC. 1983 105 488. 77 P. G. Harrison mechanism where a small amount of initial bonding occurs via attack (by oxygen) at the central carbon atom of the ketenimine. Proton transfer to the P-carbon atom then occurs at or just after the transition state without any appreciable changes in the C-0 bond distance. The reaction is therefore concerted but highly asyn- chronou~.~ Ab initio methods have also been employed in the study of the structures stabilities and bonding in a,w-dilithioalkanes' and allylsodium allyl-lithium and allylmag- nesium hydride.6 The doubly-bridged structure ( 1) was found to be the lowest-energy geometry for 1,3-dilithiopropane.Conversion of ( 1) into an allyl-lithium-LiH com-plex is exothermic by 29.0 kcal mol-'. Whereas the second lithiations of ethane and propane are favourable thermodynamically both 1,2-dilithioethane and 1,3-dilithiopropane are unstable towards conversion into LiH complexes. MNDO struc- tures for the dimers of the a,o-dilithioalkanes indicate opened tetrahedral geometries. Allyl-lithium and allylsodium are predicted to have symmetrically bridged structures (2) whereas allylmagnesium hydride prefers an unsymmetrical geometry although the barriers for 1,3 MgH shift and CH2 group rotation are quite low (3).In contrast to diphenylcarbene and essentially all substituted diphenylcarbenes which have central C-C-C bond angles of ca.150" dimesitylcarbene (4) is much closer to linearity than unhindered carbenes. When formed from dimesityl-diazomethane in n-octane or 1,l -diphenylethylene glasses dimesitylcarbene is quite persistent at 77 K showing no sign of decay over a period of 4-5 hours.7 Addi- tionally dimesitylcarbene appears to be unique amongst the diarylcarbenes thus far investigated since its triplet state cannot readily convert into the singlet state.' A new oxide of carbon tricarbon monoxide has been observed amongst the products of the pyrolysis of (5)at 1000 "C (Scheme 1).H. /H (2) M = Li or Na M. T. Nguyen and A. F. Hegarty J. Am. Chem. SOC.,1983 105 381 1. P. von R. Schleyer A. J. Kos and E. Kaufmann J. Am. Chem. SOC.,1983 105 7617. T. Clark C. Rohde and P. von R. Schleyer OrganometaNics 1983 2 1344. ' A. S. Nazran E. J. Gabe Y. LePage D. J. Northcott J. M. Park and D. Griller J. Am. Chem. SOC. 1983 105 2912. * A. S. Nazran and D. Griller J. Chem. SOC.,Chem. Commun. 1983 850. 79 C Si Ge Sn Pb; N P As Sb Bi o=c=ctlx 0 I C30 + C02 + MeCOMe + CO Scheme 1 Observed microwave frequencies for the new oxide are very close (1 part in 600) to those predicted for C30 by ab initio MO calculations. The data are fully consistent with a linear molecule whose electronic structure is well represented by the classical resonance form -C=C-C=O+.9 The 'ZZ electronic ground states of OCCO and SCCS have been studied by using non-empirical molecular structure theory which predicts the presence of strong chemical bonds in these molecules." The ability of CO to form a radical-anion CO'- which can react further with CO or C0'- with the formation of C-C bonds has been suggested by literature data on (i) the reaction of CO with alkali metals (ii) the electrochemical reduction of CO to squarate dianion (6) and (iii) adsorption of CO on metal oxides." Lithium atoms react spontaneously with CO to form Li+C02- and Li:+C022- in inert gas matrices.Li+C204- is also formed in an argon matrix. Li+C02- exhibits two structures in solid argon. One has a ring structure in which the metal interacts symmetrically with the two oxygen atoms whilst in the second isomer the lithium atom is bonded to only one of the two oxygen atoms.The C form rearranges on photolysis with a Nernst glower i.r. source to the C,,form. Similarly Li+C,O,- is converted photolyti- cally into an LiC02:C02 adduct. Li,2+C022- is produced when the concentration of alkali metal is high as a result of the reaction of dilithium or two lithium atoms with C02. Lithium oxalate is formed in concentrated matrices. A valence bond angle of 125.7" was calculated for C02-.12 0 4c-c / I 2-1 c-c 0/\ 0 (6) Methylenesulphurtetrafluoride CH,=SF4 has been synthesized by bromine- lithium exchange on BrCH2SF at low temperatures with subsequent LiF elimination.The compound is a colourless gas and has an essentially trigonal bipyramidal geometry with the methylene group occupying an equatorial site. The double bond undergoes addition reactions with polar molecules such as HF HCl HBr IC1 BrOSeF, HgF, AsF, and BrSF to give the cis adducts X-CH,-SF,-Y. In some cases elimination of SF with the formation of the carbene was 0b~erved.l~ R. D. Brown F. W. Eastwood P. S. Elmes and P. D. Godfrey J. Am. Chem. SOC.,1983 105 6496. lo G. P. Raine H. F. Schaeffer and R. C. Haddon J. Am. Chem. Soc. 1983 105 194. I' P. W. Lednor and P. C. Versloot J. Chem. SOC.,Chem. Commun. 1983 284. l2 Z. H. Kafafi R. H. Hauge W. E. Billups and J. L. Margrave J. Am. Chem. Soc. 1983 105 3886. l3 G. Kleemann and K. Seppelt Chem. Ber. 1983 116 645.P. G. Harrison The reaction of Ru(CO),( PPh3)3 with Cd(CF,),( MeOCH,CH,OMe) produces the zero-valent CF,-complex Ru( =CF,)(CO),( PPh3) which has a much reduced reac- tivity towards nucleophiles compared with an analogous Ru"-CF2 c~mplex.'~ The gas-phase pyrolyses of vinyl azide and 1 H-1,2,3-triazole have been examined by p.e. spectroscopy. In accordance with the predictions of MNDO hypersurface studies vinyl azide in its lowest thermal decomposition channel splits off nitrogen to yield predominantly 2H-aziridine which at higher temperatures rearranges to the most stable C2H3 N isomer acetonitrile (Scheme 2).15 Azidotrifluoromethane Scheme 2 reacts readily with halogen fluorosulphates and peroxydisulphuryl difluoride to form the novel compounds CF3NX(OS02F) (X = F C1 Br or OS0,F) in high yield.Reactions of the azide with ClF and BrF at ambient temperature furnish CF3NFC1 and CF3 N=NCF3 respectively but under similar conditions no reaction occurred with Cl, Br, HF or NCl. Photolysis produces CF3N=CF2 and (CF3),NN(CF3) as the major products.'6 N,N'-Dihalogenoethanediimidoyldifluorides XN=CF-CF=NX (X = C1 or Br) have been prepared simply from (CN), X2 and HgF,. Other products which were identified in the reactions included C12 N -CF2CF2- NC12 C1 N=CF-CF2- NCl, Br2N-CF2CF2-NBr, and BrN=CF-CF,-NBr,. l7 The electrophilic halides and pseudohalides XOS02F (X = C1 Br or OS0,F) add in high yield to CF2=NF to form FS020CF2NFX. Other electrophiles such as CF30F CF30C1 FOSO,F Cl, Pr, and I give no reaction under the same conditions although FOS0,F gave a small yield of the addition product FS020CF2NF2 on heating.The in situ formation of CF,NF- from CF2=NF and MF (M = K or Cs) in the presence of Cl and Br results in the formation of CF3NXF (X = C1 or F). The reactions with the imines CF3CF=NF and C2F5CF=NF proceed similarly.18 Treating CF3COCl with Me2NNH, H2NC(S)NH2 and H2NC(0)NH2 in the presence of CsF affords CF3C(0)- NH NMe CF3 C( 0)N HC(S)NHC( 0)C F, and CF,C( 0)NHC(S)N H and CF,C(O)NHC(O)NH, respectively. With hexafluoroacetone Me NNH yields CF3C( =NNMe2)CH=C(OH)CF3.'9 Cyanoformyl chloride (7) is formed in high yield by heating 2-chloro-2-( chlorothioimino)acetyl chloride at 800 "C in uacuo. Some reactions are shown in Scheme 3.20 The first phosphaketene stable at room temperature P-mesitylphosphaketene (8) has been isolated as orange crystals from the reaction shown in Scheme 4.,' A blue-black first-stage graphite fluoride C F (5 k x 2 2) in which the planar carbon-atom sheets of graphite are preserved has been made by intercalation of I4 G.R. Clark S. V. Hoskins T. C. Jones and W. R. Roper J. Chem. SOC.,Chem. Commun. 1983 719. H. Bock R. Dammel and S. Aygen J. Am. Chem. SOC.,1983 105 7681. l6 C. J. Schack and K. 0. Christie Inorg. Chem. 1983 22 22. A. Waterfield W. Isenberg R. Mews W. Clegg and G. M. Sheldrick Chem. Ber. 1983 116 724. S. C. Chang and D. D. DesMarteau Inorg. Chem. 1983 22 805. 19 H. M. Marsden K. Yasufuku and J. M. Shreeve Inorg. Chern. 1983 22 1202.20 R. Appel and M. Siray Angew. Chem. Int. Ed. Engl. 1983 22 785. *I R. Appel and W. Paulen. Angew. Chem.. In;. Ed. Cngl. 1983 22 785. C Si Ge Sn Pb; N P As Sb Bi 0 ‘C-CN +pyridine O‘C-CN EtOH -SCI, c1’ -pyndine-HCI H5C20/ (7) ’”/ LJ lH+ \ 0 N-C-CN .. w NYN COCl Scheme 3 /-( +CI,CO SitP(SiMed2 -Me,SiCl ’ Me,Si ’ ‘c1 Scheme 4 graphite with fluorine in the presence of liquid hydrogen fluoride at ca. 20 “C the oxidation proceeding bia a highly conducting second-stage salt C,2+HF2-.22 Graphite-fluorine intercalates have also been prepared in the absence of HF by exposing highly oriented pyrolytic graphite to neat fluorine gas. The rate of intercala- tion in this case is rather slow and depends strongly on the fluorine pressure although the presence of catalytic amounts of AsF, IF, or OsF considerably accelerates the reaction.X-Ray diffraction studies indicate the formation of second- third- and fourth-stage compounds ; the nature of the intercalating species however was not known.23 Reaction of SbCl with graphite at room temperature results in the forma- tion of a dilute first stage intercalate consisting of several species including SbCl, SbC152- SbC16- and SbC12-.24 The course of the intercalation has been monitored in situ by Raman spectro~copy.~~ The reaction of the potassium intercalate C8K with varying amounts of mercury allows the preparation of a series of compounds of general formula CgKHg,.26 The potassium ions in C3& can react with the three-dimensional cryptand 4,7,13,16,2 1,24-hexaoxa- 1,l O-diazabicyclo[8.8.8]hexa-cosane (‘K222’) to yield a first-stage intercalation compound with a very large interlayer spacing (15.5 A) suggesting that the potassium ions are probably within the macroheterobicyclic cage.27 22 T.Mallouk and N. Bartlett 1.Chem SOC.,Chem. Commun. 1983 103. 23 I. Palchan D. Davidov and H. Selig J. Chem. SOC., Chem. Commun. 1983 657. 24 W. Jones P. Korgul R. Schlogl and J. M. Thomas J. Chem SOC.,Chem. Commun. 1983 468. 25 R. Schlogl W. Jones and J. M. Thomas J. Chem. SOC., Chem. Commun. 1983 1330. 26 M. Rabinovitz H. Selig and J. Levy Angew. Chem. Int. Ed. Engl. 1983 22 53. 27 R. Setton F. Beguin L. Facchini M.F. Quinton A. P. Legrand B. Ruisinger and H.P. Boehm 1. Chem. SOC., Chem. Commun. 1983 36. P. G Harrison 3 Silicon and Germanium Reactive Intermediates.-The chemistry of reactive silicon intermediates is passing through a particularly interesting phase. The recent isolation of two stable disilene derivatives tetramesityl- and tetrakis(2,6-dimethylphenyl)-disilene,in the past two years has been followed by the crystal-structure determination of one of them and also by the generation of other though less stable examples. Tetramesityldisilene adopts a trans-bent geometry in the crystal with an Si=Si bond length of 216pm about 18-20 pm shorter than typical Si-Si single bond distances. Two of the cis aromatic rings are only slightly twisted relative to the approximate plane of the two silicon and four neighbouring carbon atoms whereas the other two are nearly perpendicular to this plane.28 The solid 29Si n.m.r.spectrum of this disilene (uI1 180 u2227 and u,,-15 p.p.m. downfield from Me,Si) shows an anisotropy compar- able to that of the solid 13Cspectrum of ethylene (uI 234 u22120,and a3,24 p.p.m. downfield from Me,Si). In contrast the solid 29Si n.m.r. spectrum of tetramesityl-disilane exhibits a much smaller anisotropy similar to that shown in the 13Cspectra of alkanes. Thus it appears that the electronic structure of the Si=Si double bond does indeed bear a close resemblance to that of the C=C double bond.29 Other methods for the generation of disilene derivatives include the reduction of 1,2- dihalogenodisilanes using alkali-metal naphthalide~~’ and the photolysis of cyclo- tri~ilanes~”~~ or strained bridgehead molecules such as 7,7,8,8-tetra-t-buty1-7,8-R (9) R = OMe (10) R = OH + 28 M.J. Fink M. J. Michalczyk K. J. Haller R. West and J. Michl J. Chem. Soc. Chern. Commun. 1983 1010. 29 K. W. Zilm D. M. Grant J. Michl M. J. Fink and R. West Orgnnornetallics 1983 2 193. 30 M. Widenbruch A. Schafer and K. L. mom 2.Naturforsch. Ted B 38 1983 1695. 3’ H. Watanabe T. Okawa M. Kato and Y. Nagai J. Chern. Soc. Chem. Commun. 1983 781. 32 S. Masamune H. Tobita and S. Murakami J. Am. Chem. Soc. 1983 105 6524. C Si Ge Sn,Pb; N P As Sb Bi disilabicycl0[2.2.2]0cta-2,5-diene.~~By these methods the tetra-t-butyl- tetra-i-propyl- tetrakis( 1-ethylpropyl)- and tetraneopentyl disilenes have been generated and can be trapped by the usual trapping reagents.Thus for example tetra-t butyldisilene gives the addutcts (9) and (10) with methanol and water respectively and the two products (11) and (12) with 2,3-dimethylbutadiene (Scheme 5).33 Photolysis of the cyclotrisilanes affords both the disilene and the corresponding silylene and hence trapping experiments afford products arising from both species as shown for example in Scheme 6. Several reactions of tetramesityldisilene have R2 R,Si -SIR R2Si-H Si hu b R,s~-s~R~ I 1 I /\ excess MeOH in H OMe + OMe methylcyclohexane R = 1-EtPr Scheme 6 been reported and are summarized in Scheme 7. Upon photolysis the acetone adduct (13) rearranges to the 1,3-isomer (14) probably via cleavage to the silanone and silaethene followed by ring closure in the opposite sense (Scheme 8).34On irradiation Mes2Si-SiMes, I I Mes2SiC1SiHMes2 0-CR; R;CO or CI, pentane \ HY c12 MestSi\ NO\ ,SiMes 0 Mes,Si=SiMes2 benzene+ (Mes2SiCl) 0 / \ phcrcY YH Mes,Si-SiMes Mes2Si(0R)SiHM es I1 HC=CPh Mes = 2,4,6-trimethylphenyI; R = H Me or Et; R' = Me or Ph Scheme.7 Mes,Si-0 Mes2Si-CR2I.I h, 254 nm -[Mes,Si=O] + [Mes,Si=CR,] -* Mes2Si-0 R2C-SiMes,I t R=Me Scheme 8 (14) of tetramesityldisilene in pentane solution transformation to Mes HSiSiHMesz occurs (the product expected by abstraction of hydrogen by silyl radicals) and therefore suggests radical character for the excited state of the disilene.Reaction of a solution of tetrakis(2,6-dimethylphenyl)disilene in methylcyclo-hexane at -196 "Cwith diazomethane results in the formation of the 1,2-disilacyclo-propane derivative (15) which on photolysis in the presence of trapping reagents 33 S. Masamune S. Murakami and H. Tobita Organometallics 1983 2 1464. 34 M. J. Fink D. J. DeYoung R. West and J. Michl J. Am. Chem. Soc. 1983 105 1070. P. G Harrison material Me H +R2Si/ R2SI/\ \ OMe OMe Scheme 9 gives products consistent with the formation of both silaethene and silylene (Scheme 9).35 Two other stable disilacyclopropanes 1,1,2,2-tetramesity1-3-bis(trimethyl-sily1)methylene-and 1,1,2,2-tetramesity1-3-phenyl( trimethylsily1)methylene-1,2-disilacyclopropane (16) have been prepared by the addition of dimesitylsilylene to the silapropadiene derivatives (17) (Scheme 1 O).36 R R ,SiMe \ C C=S=Si(Mes) +(MeS),Si II -/ C Me Si /\ (17) R =Me,Si or Ph (Mes),Si-Si(Mes) Scheme 10 The crystal structure of a stable silaethene was reported in 1982.37 A second stable silaethene has been described by Wiberg,38 in which the Si=C double bond is stabilized by bulky silyl groups.Synthesis of (18) is achieved by the elimination of lithium fluoride from the precursor (19) at temperatures above ca. 100 "C (Scheme 11). However at room temperature in the presence of Me3SiCl (19) is transformed rapidly into (18) which can be obtained in crystalline form by slow recrystallization Me SiMe(Bu') Me Si M e(BuI) I I Me-Si-C-SiMe h \/\SiMe, -LiF I1 F Li Me (19) (18) Scheme 11 35 S.Masamune S. Murakami H. Tobita and D. J. Williams J. Am. Chem. SOC. 1983 105 7776. 36 M. Ishikawa H. Sugisawa M. Kumada T. Higuchi K. Matsui K. Hirotsu and J. Iyoda Organometallics 1983 2 174. 37 A. G. Brook S. C. Nyburg F. Abdesaken B. Gutenkunst R. Krishna M. R. Kallury Y.C. Poon Y.M. Chang and W. Wong-Ng J. Am. Chem. SOC.,1982 104 5667. 38 N. Wiberg and G. Wagner Angew. Chem. Int. Ed. Engl. 1983. 22 1005. C Si Ge Sn Pb; N P As Sb Bi from diethyl ether at -78°C. Decomposition occurs within a few days at room temperature but rapidly at 100 "C to afford secondary products which contain dimers of (18). Several reactions of (18) are shown in Scheme 12.38 'X Me2Si-CR 'R2 Me Si-CR' R2 I1 0 F BF2 R' = SiMe,; R2 = SiMe(Bu') Scheme 12 The desorption of trimethylsilane silacyclobutane and silacyclohexane from the ( 1 10) surface of palladium metal is accompanied by dehydrogenation to silaethylene sialcyclobutadiene and silabenzene respectively which suggest a novel practical method for the synthesis of these molecules.39 The conversion of silaspiro[3.3]cyclo- heptane into the silacyclopentenes (20) and (21) appears to proceed via a thermally induced silaethene to silylene rearrangement (Scheme 13)."O The thermal decomposition of silacyclobutane leads not only as previously sug- gested to the silaethene and ethene but also to afford the silylenes SiH2 and SiHMe.41 Similarly although the direct photolysis of 1,l -dimethylsilacyclobutane results predominantly in decomposition to ethene and the silaethene in the presence of benzene decomposition to cyclopropane and dimethylsilylene also occurs due to sensitization of the silacyclobutane by triplet benzene.42 Photolysis of dibenzo- 1,1,2,2-tetramethyl-1,2-disilacyclohexa-3,5-dieneand its germanium analogue (22) results in the exclusive extrusion of the respective silylene or germylene via a route involving intramolecular ips0 aromatic silylation (Scheme 14).43 Dimesitylsilylene 39 T.M. Gentle and E. L. Muetterties J. Am. Chem. SOC.,1983 105 304. 40 T. J. Barton G. T. Burns and D. Gschneider Organometallics 1983 2 8. 41 R. T. Conlin and R. S. Gill J. Am. Chem. SOC.,1983 105 618. 42 C.George and R. D. Koob Organomeiallics 1983 2 39. 43 M. Kira K. Sakamoto and H. Sakurai J. Am. Chem. Soc. 1983 105 7469. P. G. Harrison ~e,~-hi~e (22) M = Si or Ge Q4J MMe Scheme 14 is generated by both the photolysis and pyrolysis of the oxasilacyclopropanone (23) along with the indanone (24) and can be trapped by conventional techniques. The benzosilacyclobutene (25) was formed in quite large yields (ca.40% ) in the pyrolysis reaction (Scheme I 5).44 Silylenes have been shown to undergo ring-closure reactions. (25) Scheme 15 Flash vacuum pyrolysis of methoxydisilanes has been employed to generate 1- 2- and 3-propenylsilylenes each of which affords silacyclobutane (siletene) products although probably via different mechanisms (Scheme 16):’ Methyl-5-( 1,3-pentadienylsilylene) reacts similarly (Scheme 17).46 The silylene to disilene re-arrangement has been further confirmed by generating Me SiMe2SiMeSi from 3-methoxyundecamethylpentasilane and obtaining the rearranged product Me2 SiSiMe( SiMe,).In addition the reverse rearrangement i.e. disilene to silylene has also been dem~nstrated.~’ The relative energies of isomers in the Si2H2have been calculated by ab initio SCF and electron correlation calculations. For the singlet ground-state the global minimum is a non-planar bridged structure (26) 44 W. Ando Y. Hamada and A. Sekiguchi J. Chem. SOC.,Chem. Commun.,1983 952. 45 G. T. Bums and T. J. Barton J. Am. Chem. Soc. 1983 105,2006. 46 T. J. Barton and G. T. Bums Organometallics 1983 2 1.47 H. Sakurai Y.Nakadaira and H. Sakaba Organometallics 1983 2 1484. C Si Ge Sn Pb; N P As Sb Bi Me >Me Me3Si-Si I Me -Me SiOMe 680°C d90/~ (10-4 ton) I H-Si rT CH insertion >Me Me-Si 680torr) Ae “C 37% \ Me-Si ryMe2 rfH3+ qMe + -Si Si I / / Me Me Me Scheme 16 700°C ton) Me,SiOMe + Me,Si-Si Si Me0/\Me Me / I 0-rLH,-q Si -Si / Me/\H Me Me / (13%) I Scheme 17 P. G. Harrison followed by H2SiSi (27) and trans-bent HSiSiH (28). Both H2SiSi and trans-bent HSiSiH are predicted to be local minima. In the case of the triplet ground-state H2SiSi (27) is the global minimum with the trans-bent structure (28) and a planar bridged structure (29) as local minima.48 The potential energy hypersurface for the reaction of SiH with H2 to give SiH4 has been investigated by a priori quantum mechanical methods and leads to acceptable agreement with the experimental activation energy.49 The heats of formation of 1-methylsilaethene and dimethylsily- lene of 18 and 46 kcd rno1-I have been obtained by ion cyclotron double resonance spectroscopy contradicting previous studies which indicated that the silylene was favoured in the thermal eq~ilibrium.~' Highly sophisticated calculations have been carried out on the SiCH2 system.The absolute minimum on the potential energy hypersurface is the silylidene :Si=CH2 which lies ca. 50 kcal mol-I below the linear sila-acetylene. The vinylidene isomer H,Si=C is either a shallow minimum or more likely not a genuine relative minimum at all.Sila-acetylene is predicted to have a trans-bent equilibrium geometry with a silicon-carbon bond distance of 1.635 A about 0.08 8 shorter than a 'standard' Si=C double bond distance. The bond order is suggested to be intermediate between two and three.5' Ab initio calculations on the addition of hydrogen chloride to silaethene predict that the reaction takes place with a small overall barrier and via the formation of a complex and a two-centre transition-state in which the Si-C bond distance is lengthened.' Both E and 2 isomers of 1 -methyl-1-phenyl-2-neopentylsilylene are generated by the reaction of t-butyl-lithium with chloromethylphenylvinylsilane,and can be trapped as [4 + 21 adducts by ~yclopentadiene.~~ Both silicon dichloride and silicon dibromide have been studied by electron diffraction and have XSiX bond angles of 102.7".54Thermally-generated dimethylgermylene Me,Ge undergoes concerted 1,4-addition of the linear [2 + 41 cheletropic type to give certain 1,3-dienes under (70-1 mild conditions in solution 50 "C) e.g.Scheme 1KS5 Me,Ge i-xh Scheme 18 48 H. Lischka and H. J. Kohler J. Am. Chem. SOC.,1983 105 6646. 49 R. S. Grev and H. F. Schaeffer J. Chem. SOC.,Chem. Commun. 1983 785. 50 C. F. Pau W. J. Petro and W. J. Hebre J. Am. Chem. SOC.,1983 105 16. 5' M. R. Hoffmann Y. Yoshioka and H. F. Schaeffer J. Am. Chem. SOC.,1983 105 1084. 52 S. Nagase and T. Kudo J. Chern. SOC.Chem. Commun. 1983 363. 53 P. R. Jones M. E. Lee and L. T. Lin Organometallics 1983 2 1039. 54 I. Hargittai G. Schultz J. Trernmel N. D. Kagramanov A. K. Maltsev and 0. M. Nefedov J. Am. Chem. SOC.,1983 105 2895. 55 M. Schriewer and W. P. Neumann J. Am. Chem. Soc. 1983 105 897. C,Si Ge Sn Pb; N P As Sb Bi 89 Halogenogermylenes react readily with some dinuclear transition-metal carbonyl compounds {Co,(CO), Mn2(CO),o [Fe(C5H5)(C0)2]2 etc.} to give the correspond- ing insertion products. However in contrast insertion into Group IVB metal-transition-metal bonds results in the formation of unstable adducts and the formation of the first germylenes with germanium-transition-metal bonds e.g. Scheme 19.56 Such germylenes undergo normal types of germylene reactions such as addition to dienes which unusually are thermally reversible (Scheme 20).GeF + Ph,SiCo(CO) + + Ph,SiF + F-Ge-Co(C0) GeF + 2Ph3SiCo(CO) + 2Ph,SiF + [(CO),Co],Ge Scheme 19 Y=F Y = (CO),Co Scheme 20 Tetravalent Compounds.-Insertion of the carbene :CF2 into the Si-Si bond of (FMe,Si) leads to the formation of (FMe2Si)2CF2 which undergoes Si-rather than C-alkylation with MeMgCl or MeLi. Reaction with LiA1H4 affords the corresponding silanes. In all cases the CF2 group remains inert. However the ylide (FMe2Si),C=PMe2-PMe2 is formed on treatment with Me,SiPMe2 (Scheme 2l)?' ~~e2 (FMe,Si),CF +~~e~ {(FMe,Si),CF-FMe,} I (FMe Si),C= PMe2- PMe +M$te2{ (FMe Si),C= PMe F} Scheme 21 The isomerization of the cyanate (Me3Si)3CSiMe2(0CN) to the corresponding cyanate in Ph20 at 195 "C is second order in cyanate and is catalysed by IC1 in CCI and by NaOMe in methanol.58 Reactions of 2-bis( trimethylsily1)methylpyridine with butyl-lithium in ether sol-vents and CuCl yields the thermally robust dinuclear complexes (30) (M = Li or Cu) in which the metal is not involved in electron-deficient bonding.59 The interaction 5b A.Castel P. Riviere J. Satge J. J. E. Moreau and R. J. P. Corriu Organometallics 1983 2 1498. 57 G. Fritz and H. Bauer Angew. Chem. Inr. Ed. EngL 1983 22 730. 58 C. Eaborn Y. El-Kaddar and P. D. Lickiss 1.Chem. SOC.,Chem. Commun. 1983 1450. 59 R. I. Papasergio C. L. Raston and A. H. White J. Chem. SOC.,Chem. Commun. 1983 1419. P.G. Harrison of FeI with excess Me3SiNC in thf yields ~is-[Fe(CNSiMe~)~1~] (31).60The struc- tures of two silylmethyl-lithium compounds have been determined. That of tris(trimethylsily1)methyl-lithiumthf solvate is an ate complex with [Li( thf),] cations and {Li[C(SiMe3)3]2} anions in which the lithium bridges the two organic residues.61 In contrast crystals of the thf adduct of tris(phenyldimethylsily1)methyl-lithium comprise monomeric {Li[C(SiMe,Ph),](thf)) species in which the lithium is covalently bonded to oxygen and to the central carbon of the [(Me2PhSi)3C] group and intersects strongly with the ips0 carbon atom of one of the phenyl groups without significantly distorting the hydridization of that atom (Figure 1).62 Two "C(15) Figure 1 Molecular structure of Li[C(SiMe Ph),](thf) (Reproduced from J.Chem. SOC.,Chem. Commun. 1983 1390) C N SiMe R. A. Jones and M. H. Seeberger J. Chem. SOC.,Dalton Trans. 1983 181. 6' C. Eaborn P. B. Hitchcock J. D. Smith and A. C. Sullivan J. Chem. SOC.,Chem. Commun. 1983 827. C. Eaborn P. B. Hitchcock J. D. Smith and A. C. Sullivan J. Chem. Soc. Chem. Commun. 1983 1390. C Si Ge Sn Pb; N P As Sb Bi 91 independent determinations of the structure of the ether solvate of the lithium disilazane {Li[N( SiMe,),](OEt,)), have both of which agree. The lattice contains dimeric molecules with the silazane groups acting as bridging ligands between the two three-coordinated lithium atoms. Several new compounds containing the Si -N -transition-metal linkage have been synthesized most of which are accompanied by crystal-structure determina- tions.The reaction of LiN(SiMe2CH,PR2)2 with either zirconium( IV) or hafnium( IV) chloride generates the new complexes MCl2[N(SiMe,CH2PR3),] (M = Zr Hf; R = Me Ph) in which both of the potentially terdentate ligands bind the Group IVA metal in a bidentate fashion only. The molecules thus contain both co-ordinated and unco-ordinated phosphines. Structural studies of the complex with M = Zr and R = Me show that the geometry at the central metal is distorted octahedral with trans-chloride and cis-phosphine ligands. The molecule is chiral in both the crystal and in solution by virtue of a 'gear' effect of the two bulky disilylamide ligand~.~' The dialkyls R,Zr[N( SiMe,),] (R = Me Et or CH,SiMe,) decompose thermally at 60 "C and lo- torr with elimination of the alkane (CH4 C2H6 or Me,%) to give the bridging carbene complex ZrCHSiMe,NSiMe,[N(SiMe,),], which has the dimeric structure (32) comprising three fused planar four-membered rings giving the molecule a 'tub' conformation.The hafnium dialkyls decompose in a similar manner although in this case the product could only be characterized as its pyridine Inadduct kfCHSiMezNSiMe3[N(SiMe3)2](CsHsN)2.contrast the titanium alk 1 Me Ti N(SiMe,),], is stable up to 190 "C; nevertheless the carbene complex iCHSiMe NSiMe,[N( SiMe34),], was obtained by the sodium-amalgam reduction of Cl,Ti[ N( SiMe3)J2 .66 The zirconium and hafnium carbene complexes react with 1,2-bis(dimethy1phys~hino)ethane (dmpe) at room temperature to give the bis(metallacycle) M[CH2SiMe2NSiMe3l2(dmpe).The same complexes can also be prepared from the dialkyls R,M[N(SiMe,),], and dmpe at 60 "C and are formally derived by addition of a y-CH bond of a [N(SiMe,),] group to a metal-carbon(car- bene) bond.The zirconium complex has idealized C2 symmetry with the two phosphorus atoms occupying two cis sites trans to the two nitrogen atoms and the two remaining trans sites occupied by the carbon atoms of the metallacycle rings in a distorted octahedral arrangement. The complex also reacts with carbon monoxide under pressure (19atm) at room temperature in pentane to give Zr[CC( =CH2)SiMe,NSiMe3],(dmpe).67The disproportionation of the hafnium complex HfC1[N(SiMe2CH2PMe2)2]2,with excess hafnium( IV) chloride results in the formation of the mono-amide complex HfC13 N( SiMe2CH PMe,) HfCl, which can be converted into Hf(BH4),[N(SiMe2CH2PMe2),] and Hf( BH,) by reaction with excess LiBH,.Reaction of the tetrahydroborate complex with Lewis bases yields the dinuclear complex {Hf[N(SiMe2CH,PMe,)2]}2(H),(BH4)3.68 The platinum complex Pt{P(=NBu')[N(SiMe,),]}, reacts with the alkenes C,Cl,H C2C14 C,H,(CN), and C2(CN) to afford the complexes (33)-(35)' respectively; the 63 P. M. Engelhardt A. S. May C. L. Raston and A. H. White J. Chem. SOC. Dalton Trans. 1983 1671. 64 M. F. Lappert M. J. Slade A. Singh J. L. Atwood R. D. Rogers and R. Shakir J. Am. Chem. SOC. 1983 105 302. 65 M. D. Fryzuk H. D. Williams and S.J. Rettig Inorg. Chem. 1983 22 863. 66 R. P. Planalp R. A. Andersen and A. Zalkin Organometallics 1983 2 16. 5? R. P. Planalp and R. A. Andersen Organometallics 1983 2 1675. 68 M. D. Fryzuk and H. D. Williams Organometallics 1983 2 162. P. G. Harrison complex (36) is obtained with diphenyla~etylene.~~ Both Me SiNSO and Me,SiN=S=NSiMe react with tin(1v) chloride to yield the 1 1 adduct Me3SiN=S=NSiMe3-SnCl, in which the silylsulphurdi-imide ligands chelates the tin.70 L C(CN)R L c’ \/ \/ Pt Pt /\ L C(CN)R L /\C (35) R =H \Ph R =CN (36) Four- and five-membered silylhydrazine ring compounds such as (37) and (38) are obtained by the reaction of N,N-bis( fluorasily1y)amines with dilithiated hydra~ines.~~ (39) can be prepared by Similar 1,3-diphospha-2,4-disilacylobutanes ring closure of fluorodialkylsilyl(t-buty1)phosphinesusing t-BuLi whilst ring closure of the bis(phosphane) (40) affords the 1,2,3-triphospha-4-sila-cyclobutane derivative (41).72 The reaction of silyliminofluorosulphates R,SiNSOF, with the salts [M(SO,),](AsF,) (M =Co Ni or Cu) in liquid sulphur dioxide results in the formation of the metal iminofluorosulphates M( NSOF2)2.73 Cyclocondensation of 1,2-dipotassium 1,2-di-t-butyldiphosphide with SiC1 leads to the formation of tetraphosphasilaspiro[2.2]pentane (42) as a mixture of stereoisomers the melt of which rearranges at temperatures of 135-155 “C to the silaphosphane (43).The structure of (43) is most unusual and comprises three-membered Sip2 four mem- bered [SizP2] and five-membered [Sip,] rings in the same m01ecule.’~ R R CMe /CM% P I R Si,,;\ R\ /R R\SrN,Si/R /Si /R R\Si/ ‘H Si /Si \ /\ \ R’k-N ‘\R R’P R R /P-H R/ R / \ I N H R CMe Me,C /\ H R (38) (39) (40) (37) 6Y 0.J. Scherer R. Konrad E. Guggolz and M. L. Ziegler Chem. Ber. 1983 116 2676. H. W. Roesky H. G. Schmidt M. Noltemeyer and G. M. Sheldrick Chem. Ber. 1983 116 1411. 70 ”W. Clegg M. Haase H. Hluchy U. Klingebiel and G. M. Sheldrick Chem. Ber. 1983 116 290. 72 W. Clegg M. Haase U. Klingebiel and G. M. Sheldrick Chem. Ber. 1983 116 146. 73 R. Hoppenheit R. Mews M. Noltemeyer and G. M. Sheldrick Chem. Ber. 1983 116 874. 74 M. Baudler T. Pontzen U. Schings K. F. Tebbe and M.Feher Angew. Chem. Int. Ed. Engl. 1983 22 775. C,Si Ge,Sn Pb;N P As Sb Bi CMe, I R = Bu' R CMe (42) (43) (41) Trichlorosilanol Cl,SiOH is formed by photolysis of C13SiH and oxygen in silicon tetrachloride uia a radical-chain pathway. The hydfoperoxide could not be detected.% Electron-diff raction studies of bis(methylsily1)ether and bis( dimethyl- sily1)ether in the gas phase has shown that the former has at least two conformers. The major one (64%) has the methyl groups twisted by 124" and 58" away from the positions in which the Si-C bonds are trans to Si-0 bonds. In the dimethylsilyl ether the silyl groups are twisted by 10 1" and 41O away from the symmetrical position in which both Si-H bonds are cis to Si-0 bonds so that the dimethylsilyl groups are staggered with respect to each other.76 The hydrolysis of dichlorosilane in dichloromethane solution either with a stoicheiometric amount of water at -30 to -20 "C or by slow controlled addition of a slight excess of water at 0 "C results in the formation of siloxanes of the type [HZSiO],.In the volatile fraction oligomers with n ranging from 4up to 23 were found.77 Tetramethyldisiloxane and poly(methy1- siloxane) react with chlorine to give 1,3-dichlorotetramethyldisiloxane and poly(methylchlorosiloxane) respectively which undergo substitution with sodium cyclopentadienide to afford the corresponding cyclopentadienyl derivatives. These in turn either with sodium metal or Bu"Li give anionic cyclopentadienide derivatives which react with TiC1,-2py to yield (44) and (45).78 (44) (45) Following the controversy over the claim of a square-planar geometry for bis( o-phenylenedioxy)silane the structures of two related compounds bis( 1,8-naph- tha1enedio~y)silane~~ and bis(tetramethylethylenedioxy)silane,80 have been deter- mined and further refute the original claim.In both the geometry at the spiro silicon atom is distorted tetrahedral the greater distortion observed in the second compound being attributed to the constraints of the five-membered ring rather than to any tendency towards planarization. The racemization of tris(tropolonato)silicon(rv) anion in 1,1,2,2-tetrachloroethaneand acetonitrile follows first-order kinetics and 75 R. Gooden Inorg. Chem. 1983 22 2212.76 D. W. H. Rankin and H. E. Robertson J. Chern. Soc. Dalton Trans. 1983 265. 77 D. Seyferth C. Prud'homme and G. H. Wisernan Inorg. Chem 1983 22 2163. 78 M. D. Curtis J. J. D'Emco N. Duffy P. S. Epstein and L. G. Bell Organornetallics 1983 2 1808. 79 W. Bibber C. L. Barnes D. van der Hlem and J. J. Zuckerman Angew. Chem. Inr. Ed. EngL 1983 22 501. 80 D. Schomburg Angew. Chern. Int. Ed. Engf. 1983 22 65. 94 P. G. Harrison is not accompanied by any detectable decomposition or ligand subsitutition but is promoted by trichloroacetic acid. A mechanism involving bond rupture to give five-co-ordinated intermediates was proposed.” The co-facially joined metallo- macrocyclic polymer {M(Pc)O) (Pc = phthalocyaninato; M = Si Ge or Sn) are precursors for a new class of electrically conductive polymers and their synthesis spectra and structural transport magnetic and optical properties have been reported.82983 The heavy-atom skeleton framework of germyl monothioacetate is almost planar in the gas phase with the Ge-S and C=O bonds in a mutually cis arrangement.84 Ab initio MO calculations using double 5 basis sets have shown that (46) is the lowest energy geometry for the adduct SiF4-NH3.85 The 1 1 adducts of trimethyl- iodosilane and trimethylbromosilane with pyridine comprise the four-co-ordinated [Me,Si.py]+ cation and halide anion.86 The silicon atom in 1-(trifluorosilyl)- 1,2,3,4- tetrahydro- 1,lO-phenanthroline is five-co-ordinated with a trigonal bipyramidal ge~metry.~’ Cyclopropyl- cyclobutyl- and cyclopentyl-trichlorogermaneshave been prepared by the organolithium or Grignard route from GeCl, and can be reduced to the corresponding germanes using LiA1H4.88 Diethyldichlorosilane reacts with alkali metals to produce the diethylcyclosilanes (Et,Si),(n = 4-8) the particular products obtained depending upon the alkali metal and conditions employed.With lithium in thf the major products are the n = 5 and n = 7 rings whereas the n = 4 ring is the major product from sodium in toluene. Photolysis of the n = 5-8 rings leads to the elimination of Et,Si and the formation of the next smaller ring.89 The reaction of (Et,Si) with 1.1 equivalents of sulphur at 50 “C gives high yields of (47) whereas reaction with 2 equivalents at 190°C affords (48) and (49) as the major products along with small amounts of (50).This latter heterocycle appears to arise from the reaction of (48/49) and sulphur which also produces diethylsilanethione [Et Si=S] as a reactive intermediate.” Reaction with alkynes in the presence of palladium catalysts results in ring expansion to yield 3,4,5,6-tetrasilacyclohexenes (5 1) and ultimately 1,4-disilacyclohexa-2,5-dienes (52). With isoprene two addition products (53) and (54) are formed. rn-Chloroperbenzoic acid causes rapid oxidation to the siloxanes (Et Si),O (n = 1-4). Ring-opening occurs with Clz Br, I, LiAlH4 HCl HBr H20 EtOH and acetic acid and slowly with phenyl-lithium to give 1,.l-disubstituted linear tetrasilanes.” Reaction of (C Me 1r),CI4 with triethylsilane gives initially (C,Me Ir),H2C12 and then (C Me,Ir( H),(C1)SiEt3 finally giving the complex C,Me,Ir( H),( SiEt3)2.92The symmetrically-bridged diruthenium complex (55) is obtained from the reaction of ” T.Inque Znorg. Chem. 1983 22 2435. 82 C. W. Dirk T. Inabe K. E. Schoch and T. J. Marks J. Am. Chem. Soc. 1983 105 1539. 83 B. N. Diel T. Inabe J. W. Lyding K. F. Schoch C. R. Kannewurf and T. J. Marks J. Am. Chem. SOC.,1983 105 1551. 84 E. A. V. Ebsworth C. M. Huntley and D. W. H. Rankin J. Chem. SOC.,Dalton Trans. 1983 835. 85 C. J. Marsden Inorg. Chem. 1983 22 3177. 86 K. Hensen T. Zengerly P. Pickel and G. Klebe Angew. Chem. Int. Ed. Engl. 1983 22 725. 87 G. Klebe K. Hensen and H. Fuess Chem. Ber. 1983 116 3125. 88 M.Dakkouri and H. Kehrer Chem. Ber. 1983 116 2041. 89 C. W. Carlson and R. West Organometallics 1983 2 1792. C. W. Carlson and R. West Organometallics 1983 2 1798. 9’ C. W. Carlson and R. West Organornetallics 1983 2 1801. 92 M. J. Fernandez and P. M. Maitlis Organometallics 1983 2 164. C,Si,Ge Sn,Pb; N P As Sb Bi 95 EtZ Et,Si”\I S Et,Si. Si Et2Si/”SiEt2 S I I Et,Si\ ,SiEt Et2SiNS\SiEt2I I S .,SiEt2St 2.072 Et2 Et2 Ru3(CO) and Ph2PCH,SiMe2H which on treatment with trifluoroacetic acid gives the mononuclear phosphinomethyldimethylsilanol complex (56).93The compounds OS~(CO)~~(S~XC~~), (X = Me or C1) have been isolated from the reaction of OS~(CO)~~ with the appropriate silane C1,XSiH at 140 “C under a carbon monoxide pressure (80 atm).The structure of the X = C1 complex has a crystallographic centre of symmetry with a linear SiOs3Si chain which is preserved in solution. The structure of 0s3(P-H)~(CO)~( SiC13)3 is different and has a triangular arrangement of osmium atoms which lie on a mirror plane with the silicon atoms also on the plane.94 The complex (OC)50sOs(C0)3(GeC13) is formed from the reaction of Os(CO) and GeC1,.95 The germanium-manganese complex (57) may be prepared in quite high yield by reaction of gaseous germane with solvent-stabilized (C,H,)Mn(CO) in the presence of traces of acid. (C,Me,)Mn(CO) gives exclus- ively the orange complex (p2-Ge)[(C,Me,)Mn(C0)2]2 having a strictly linear Mn-Ge-Mn skeleton. Solutions of (57) in thf react with diazomethane at low temperatures to afford brown air-stable crystals of the p3,7 methylenegermanediyl complex (58).The main product from the reaction of silane with (C5H,)Mn(CO),.thf was (59).96 Solid-state 29Si and 27Al n.m.r. with magic-angle spinning is now rather a standard technique for the investigation of silicate and aluminosilicate materials and several studies have appeared recently. The surface of dehydrated silica gel has been shown 93 M. J. Auburn R. D. Holmes-Smith S. R. Stobart M. J. Zaworotko T. S. Cameron and A. Kumari J. Chem. SOC.,Chem. Commun. 1983 1523. 94 A. C. Willis G. N. van Buuren R. K. Pomeroy and F. W. B. Einstein Inorg. Chem. 1983 22 1162. 95 F. W. B. Einstein R. K. Pomeroy P. Rushman and A. C. Willis J. Chem. Soc. Chem. Commun. 1983 854.96 W. A. Herrmann J. Weichmann U. Kusthardt A. Schaffer R. Horlein C. Hecht E. Voss and R. Serrano Angew. Chem. Int. Ed. Engl. 22 1983 979. P. G. Harrison to comprise separate regions resembling the 100 and 11 1 faces of P-cri~tabolite:~ and a double-ring silicate has been identified for the first time in the ZSM-5 synthesis mixture.98 A correlation between the average Si-0-T (T = tetrahedral atom) and the associated isotropic 29Si chemical shift in zeolite materials has been e~tablished,~~ but 29Si spin-lattice relaxation times in aluminosilicates vary over three orders of magnitude and can be extremely long.'00 Eight distinct tetrahedral sites for silicon have been identified in freshly crystallized (hexagonal) synthetic cordierite Mg2Al4Si5Ol8 and have been assigned as four in the chain manifold and four in the six-membered aluminosilicate rings.However there are only two sites one in the rings and one in the chains in the aged (orthorhombic) product. The Si :A1 ratios within each manifold can also be determined from the spectra which also allow the course of Si,Al ordering to be charted as thermodynamic equilibrium is approached."' The reaction of synthetic zeolite Na-Y with SiC14 vapour at 560 "C yields an essentially aluminium-free faujasite structure which is highly crystalline and whose n.m.r. spectrum exhibits a single peak characteristic of regular Si(4Si) ordering. The 27Al spectrum of the dry dealuminated material shows two peaks one due to residual lattice aluminium and the other to AlC14-.The 27Al spectrum of washed dealuminated zeolite Y contains two peaks one also due to residual aluminium still on tetrahedral sites in the lattice and an additional peak due to octahedrally co-ordinated cationic aluminium in the zeolite channels. lo* 4 Tin and Lead Bivalent Compounds.-Reaction of tin( 11) chloride with Li( CPh=CPh2) at -78 "C in diethyl ether-hexane-thf gives a deep-red solution believed to contain the 97 D. W. Sindorf and G. E. Maciel J. Am. Chem. Soc. 1983 105 1487. 98 G. Boxhoorn 0.Sudmeijer and P. H. G. van Kasteren J. Chem. Soc. Chem. Commun. 1983 1416. 99 R. H. Jarrnan J. Chem. Soc. Chem. Commun. 1983 512. I00 P. F. Barron R. L. Frost and J. 0. Skjemstad J. Chem. SOC.,Chem. Commun 1983 581. 101 C. A.Fyfe G. C. Gobbi J. Klinowski A. Putnis and J. M. Thomas J. Chem. Soc. Chem. Cornmun. 1983 556. 102 J. Klinowski J. M. Thomas C. A. Fyfe G. C. Gobbi and J. S. Hartman Inorg. Chem. 1983 22 63. C,Si,Ge Sn Pb; N P As Sb Bi 97 unstable dialkenyltin( 11) compound.'03 Chemistry based on stannocene continues to prosper. Cowley'@' has demonstrated the dilithiation to 1,l '-dilithiostannocene which reacts with Me3SiCl and (Pr',N),PCI to give (60) and (61) respectively. The latter derivative was characterized by X-ray analysis. Reaction of pentamethylcyc- lopentadienyltin trifluoromethanesulphonate with B13 in dichloromethane results in tin-boron exchange and the formation of the (C,Me,)BI+ cation."' Related to stannocene is the unusual complex [(C,H,)Co( C2B2C)I2Sn (C2B2C= 4,5-diethyl- 1,3-dimethyl- 1,3-diborolenyl) prepared from the sandwich anion and tin(I1) chloride which has a 'tetradecker' structure bent at the central tin atom.lo6 The germanium tin and lead bis(trimethylsilyl)amides M[N(SiMe3),12 (M = Ge Sn or Pb) are 'V'-shaped monomers in both the gas phase and in the crystal (M = Sn or Pb) although the valence angle at the metal varies somewhat between the phases."' The tin bis( arenedithiolate) Sn( SC6H2B~t3-2,4,6)2 is also 'V-shaped but the tin( 11) and lead( 11) bis(2,6-di-isopropylbenzenethiolates)are trimeric with both bridging and terminal thiolate ligands and four-co-ordinated (central) and three-co-ordinated (terminal) metal atoms.lo* Dimeric [(Me SiO),Sn] has been obtained by the protolysis method from stannocene and trimethylsilanol in t~luene.'~' Veith' lo has described two more stannazane cage molecules Sn,( NBU~)~ and Sn,(NBu'),O.Molecules of the former are held together by van der Waal's forces whereas the latter forms dimers via weak intermolecular C + Sn interactions. The tin atoms in di-ammonium trichlorostannate chloride monohydrate form three short contacts to chlorine with a fourth much longer contact to the chloride anion. Neighbouring SnCl,. C1-units are connected by two longer Sn--Cl bridges forming a chain structure and completing a severely distorted octahedral environ- ment at tin. The anionic chains ammonium cations and the water molecule partici- pate in a three-dimensional hydrogen-bonded network."' The basic unit of the thiourea complex of tin(r1) chloride is the formula unit SnCI,(SC(NH2),} but are tightly bound into chains by both chlorine and sulphur bridging.Interchain N-H. -C1 hydrogen-bonding again results in a three-dimensional structure.' '' Lead-207 chemical shift data have been recorded for a number of bivalent lead compounds including lead( 11) nitrate acetate and perchlorate (all in water) lead(1x) pentafluorobenzoate (in thf) and two lead( 11) dithiophosphoridates (in CH2C12 and thf). In all cases only one signal was observed which in most cases was a consequence of the occurrence of equilibria which are rapid on the n.m.r. time scale. In these cases equilibrium constants were computed and in the case of lead(r1) acetate thermodynamic quantities were derived." Following the determination of the crystal I03 C.J. Cardin D. J. Cardin R. J. Norton H. W. Parge and K. W. Muir J. Chem. SOC. Dalton Trans. 1983 665. I04 A. H. Cowley J. G.Lasch N. C. Norman C. A. Stewart,andT. C. Wright Organometallics 1983,2 1691. 105 F. Kohl and P. Jutzi Angew. Chem. In!. Ed. Engl. 1983 22 56. I06 H. Wadepohl H. Pritzkow and W. Siebert Organornetallics 1983 2 1899. I07 T. Fjeldberg H. Hope M. F. Lappert P. P. Power and A. J. Thome J. Chem. SOC Chem. Commun. 1983 639. I08 P. B. Hitchcock M. F. Lappert B. J. Samways and E. L. Weinberg J. Chem. Soc. Chem. Commun. 1983 1492. 109 W. W. Du Mont and M. Grenz Z. Naturforsch. Teil B 38 1983 113. 110 M. Veith and 0. Recktenwald Z. Naturforsch.Teil B 38 1983 1054. Ill P. G. Harrison B. J. Haylett and T. J. King Inorg. Chim Act4 1983 75 265. P. G. Harrison B. J. Haylett and T. J. King Inorg. Chim. Acta 1983 75 259. 113 P. G. Harrison M. A. Healy and A. Steel J. Chem. SOC.,Dalton Trans. 1983 1845. 98 P. G. Harrison structure of a lead(r1)-EDTA complex last year formation constants in the Pb"- EDTA and Pb"-D-penicillamine systems have been determined.' l4 Adenosine 5'-triphosphate forms a complex of composition Pb2ATP-2H20 with lead( 11) acetate or nitrate in aqueous media. The complex is only sparingly soluble in water but the observation of two distinct 207Pb resonances indicates the presence of two different lead sites. Both this complex and the complex of lead(rr) acetate with dimethylphosphite decompose spontaneously in water or methanol the latter by stepwise elimination of methanol and acetic acid affording lead( 11) phosphite as the final product.' l5 The crystal structure of a hexalead chloride triorthoborate oxide Pb40{ Pb2( B03)3C1} can be regarded as being built up of [Pb,O]tetrahedra [Pb-Pb]dumbells isolated planar [BO,] groups and isolated chloride ions.' l6 Like the thallium compound T1Pb804Br9 Pb9O4Br1 also contains the [Pb804] group which may be considered as four [Pb40] tetrahedra which share common edges with each other.The central [Pb404] cube is reminiscent of the 'cubane' units in the [Pb,(OH);+] The lead atom in PbSO is in a distorted monocapped trigonal prismatic oxygen co-ordination closely related to PbS04.' '' SiMe P( Pr i2N)2 (-J (-J Sn &S'Me3 .-Tetravalent Derivatives.-As in recent years several novel organotin compounds have been synthesized and many characterized crystallographically.The addition of a stoicheiometric amount of Me,SnCl to the di-Grignard reagent BrMgCH2CH2CH2MgBr gave the cyclic oligomers (62)-(64) in ca. 70% yield. Only indirect evidence for the formation of 1,l '-dimethylstannacyclobutane could be obtained due to its high volatility and instability. Nevertheless 1,1,3,3-tetramethylstannacyclobutane could be isolated albeit in only 5% yield. ' l9 Similar Me \ fi/Me Mr:nT;e Me ('1,Me Me-Sn Sn-Me c: z:, S Me/'usn\Me L Me Me d Me7U''Me Me Me (62) (63) (64) I14 M. J. Willes and D. R. Williams Inorg.Chim. Acta 1983 80 L35. 'I5 P. G. Harrison and M. A. Healy Inorg. Chim. Acta 1983 80 279. I16 H. Behm Acta Crystullogr. 1983 C39 1317. 1 I7 H. L. Keller Angew. Chem. Int. Ed. Engl. 1983 22 324. 118 H. D. Lutz W. Buchmeier and B. Engelen Z. Natwrforsch. Teil B 1983 38 523. I19 J. W. F. L. Seetz G. Schat 0. S. Akkerman and F. Bickelhaupt J. Am. Chem. Soc. 1983 105 3336. 99 C Si Ge Sn Pb; N P As Sb Bi H Fe Fe techniques have been employed to prepare the large stannacycloalkanes (65) and (66).I2O The bridgehead carbon atom of tri-stanna-adamantane (67) is one of the most flattened methine carbon atoms known leading to an increased reactivity of the bridgehead hydrogen. 12' Treatment of 1,l'-dilithioferrocene-tetramethylethyl-enediamine with dibutyltin dichloride affords the doubly-bridged compound (68) (R = Bun).'22 Penta(methoxycarbony1)cyclopentadiene reacts with bistributyltin oxide to give the salt [Bu3 Sn(OH2),+][C5 (CO,Me),-] in which the tin has trigonal bipyramidal geometry with apical water d0n0rs.l~~ The use of sterically crowded organic groups usually produces compounds which are generally structurally quite different from the other more typical members.Thus syntheses involving 2,6-diethylphenylmag- nesium bromide result in the formation of hexakis(2,6-diethylphenyl)cyclotristan-noxane which has a planar [Sn,O,] ring rather than a more usual polymeric structure. Reduction of the corresponding diaryltin dichloride using lithium naphthaleneide gives hexakis(2,6-diethylphenyl)cyclotristannane the only example known to date.'24 Crystals of 1-methylstannatrane hexahydrate comprise trimeric units (69) in which the geometry around the central tin atom approximates closely a pentagonal bipyramid.The two crystallographically equivalent end tin atoms have distorted octahedral geometry. N.m.r. data suggest that the trimer unit is retained in ~olution.'~~ The carboxylato group in triphenyltin 2-hydroxy-5-methylazobenzoatechelates the tin atom in a distorted cis-SnC302 five-co-ordinated geometry. Unlike all other triorganotin carboxylates studied to date intermolecular association is completely absent.'26 N-(Trimethylstanny1)succinimide has a helical-associated polymeric I 20 M. Newcomb Y. Azuma and A. R.Courtney Organornetallics 1983 2 175. I21 A. L. Beauchamp S. Latour M. J. Olivier and J. D. Wuest J. Am. Chem. SOC.,1983 105 7778. 122 A. Clearfield C. J. Simmons H. P. Withers and D. Seyferth Inorg. Chim. Acfa 1983 75 139. I23 A. G. Davies J. P. Goddard M. B. Hursthouse and N. P. C. Walker J. Chem. SOC.,Chem. Commun. 1983 597. I24 S. Masamune L. R. Sita and D. J. Williams J. Am. Chem. SOC.,1983 105 630. I25 R. G. Swisher R. 0.Day and R. R. Holmes lnorg. Chern. 1983 22 3692. I26 P. G. Harrison K. Lambert and T. J. King J. Chem. SOC.,Dalfon Trans. 1983 363. P. G. Harrison structure with a trans-0 + Me,Sn-N geometry at tin.12' The triorganometal groups in triorgano-tin and -lead derivatives of N-acetylamino-acids are co-ordinated by unidentate carboxylic groups and the oxygen atom of the amidocarbonyl group.Co-ordination by NH groups does not occur.128 Reaction of chloro{2-(phenylazo)phenyl} mercury with tin metal leads to the formation of dichlorobis 2-(pheny1azo)phenyl tin in which the tin atom is six-co- ordinated in a very distorted fashion with two cis-chlorine and cis-nitrogen atoms in the equatorial plane and two carbon atoms of the ortho-metallated phenyl groups considerably displaced from the trans-axial position.129 Distorted octahedral co- ordination is also found in complexes of diorganotin dichloride with 1,2-bis(diphenylphosphory1)-ethaneand -ethylene (dppoe and dppoet respectively). In the structure of Bu2SnCl2.dppoe one oxygen atom is bonded more loosely than the other,',' whereas in the two complexes R2SnC12-dppoet when R = Bun the ligand chelates symmetrically but when R = Pr" the ligand is essentially uniden- In bis[bis(O,O'-diphenylthiophosphato)diphenyltin]hydroxide an inter-mediate in the hydrolysis of bis( O,O'-diphenylthiophosphato)diphenyltin the molecular units associate through double hydroxide bridges to form centrosymmetric dimers with a planar central [Sn20,] ring.The co-ordination at the tin atoms is best described as a badly distorted trigonal bi~yramid.',~ The phenylphosphonate and phenylarsonate derivatives Me2Sn( PhPO,) Me2 Sn( PhAsO,) and Bu2 Sn(PhAsO,) can be isolated in two modifications depending upon their method of preparation. The &modifications and the single modification of Ph2Sn(PhP03) appear to have infinite-chain structures whilst the a-modifications are suggested to have two- dimensional sheet structure^.'^^ The five-membered ring in Me2SnSCH2CH2S has an envelope conformation with a short intermolecular Sn...S contact completing a distorted trigonal bipyramidal geometry at tin.'34 127 F. E. Hahn T. S. Dory C. L. Barnes M. B. Hossain D. van der Helm and J. J. Zuckerman Organometallics 1983 2 969. G. Roge F. Huber H. Preut A. Silvestri and R. Barbieri J. Chem. SOC.,Dalton Trans. 1983 595. I29 J. L. Brianso X. Solans and J. Vicento J. Chem. Soc.. Dalton Trans. 1983. 169. 130 9. G. Harrison N. W. Sharpe C. Pelizzi G. Pelizzi and P. Tarasconi J. Chem. SOC.,Dalton Trans. 1983 921. 131 P. G. Harrison N. W. Sharpe C.Pelizzi G. Pelizzi and P. Tarasconi J. Chem. SOC.,Dalton Trans. 1983 1687. 132 F. A. K. Nasser M. B. Hossain D. van der Helm and J. J. Zuckerman fnorg. Chem. 1983 22 3107. 133 D. Cunningham P. Firtear K. C. Molloy and J. J. Zuckerman J. Chem. Soc. Dalton Trans. 1983 1523. I34 A. Secco and J. Trotter Actu Crysfallogr. 1983 C39 451. C Si,Ge Sn Pb; N P As Sb Bi 101 Several papers report the use of triorganostannyl-dithiocarboxylates and -thioamides as ligands towards transition metals. The esters Ph SnCS R replace ethylene in (PPh3) PtC2H4 to give the platinum complexes (PPh,) Pt(Ph3 SnCS R). Molecular structure studies of the complex with R = Me show that the ligand is bonded in an q2 fashion via the C=S group with the other sulphur being unco- ordinated.The initial products of the reaction with the thioamides Ph3 SnCSN' (N' = NMeH pyrrolyl) are also q2complexes but undergo an internal oxidative- addition to give the complexes (PPh,),Pt( Ph)(Ph,SnCSN') which contain a direct Pt-Sn bond.13' The lithium salt Ph3CS2Li reacts with pentacarbonyl-manganese and -rhenium bromides to afford the complexes Ph,SnCS,M(CO) (M = Mn or Re) which undergo thermal CO-substitution with phosphines and phosphite~.'~~,'~~ Tin-1 19 n.m.r. data for this type of complex and of the free ligands have been reported.'38 The complex cis-RCl,(CO)( PPh3) reacts with tin( 11) chloride dihydrate in acetone to yield solutions which are active in the catalytic hydroformulation of olefins. N.m.r. data show the solutions to contain the cationic complex trans-RCl(C0)- (PPh,),+ and four anionic complexes three of which have been identified as Pt( SnC13)s3- trans-PtC1( SnCl,),( PPh3)- and trans- PtC1( SnC13),(CO)-.Attempted isolation leads to further rearrangement reactions and only cis-PtC12(PPh3)2 could be isolated. The reaction is extremely solvent-dependent ligand rearrangement occurring in acetone and acetonitrile but in chloroform only simple insertion of SnC1 into one Pt-C1 bond is observed. Comparison of cis-PtC1,(L)(PR3) (L = CO SR2 or p-XC6H4NH2) with cis-PtCi2L2 and cis-PtCl,(PR,) shows that the former is the most active catalyst precursor in the presence of tin( 11) ~hloride.'~~-'~~ The tris(trimethylstanny1) group has been employed as a bulky ligand in the dimolyb- denum complex Mo2Sn( SnMe,) (NMe2)4.142 The first organosilylplumbane Pb( SiMe3)4 has been synthesized by the reaction of lead(11) chloride with Mg(SiMe,) in diethyl ether at -78 OC.14 5 Nitrogen The only reaction of any consequence that takes place in the equimolecular MaN03- KN03 system over the temperature range 500-600°C is the reaction:'@ NO3-NO2-+ )O Double-6 ab initio calculations on dinitrogen tetroxide are in excellent agreement with the experimentally determined structural pararneter~.'~' Molecules of dinitrogen pentoxide in the gas phase at -11 "C comprise two -NO2 groups joined by a fifth 135 A.W. Carr R. Colton D. Dakternieks B. F. Hoskins and R. J. Steen Inorg. Chem. 1983 22 3700, I36 T. Hattich and U. Kunze Z.Nuturforsche. Teil B 1983 38 655. 137 U. Kunze and T. Hattoch Chem. Ber. 1983 116 3071. B. Mathiasch and U. Kunze Inorg. Chim. Actu 1983 75 209. 139 G. K. Anderson H. C. Clark and J. A. Davies Inorg. Chem. 1983 22 427. I40 G. K. Anderson H. C. Clark and J. A. Davies Inorg. Chem. 1983 22 434. 141 G. K. Anderson C. Billard H. C. Clarke J. A. Davies and C. S. Wong Inorg. Chem. 1983 22 439. 14' M. J. Chetcuti M. H. Chisholm H. T. Chiu and J. C. Huffrnan J. Am. Chem. Soc. 1983 105 1060. I43 L. Rosch and U. Starke Angew. Chem. Int. Ed. Engl. 1983 22 557. 144 D. A. Nisseren and D. E. Meeker Inorg. Chem. 1983 22 716. 145 C. W. Bauschlicher A. Komornicki and B. Roos J. Am. Chem. SOC.,1983 105 745. 102 P. G. Harrison oxygen atom by non-collinear bonds.The -NO groups undergo large-amplitude torsional motion about a point of minimum energy corresponding to C symmetry for the molecule with the dihedral angles between these groups and the N-0-N plane each about 30°.146The structure of the gaseous H,NO2-ion in the negative chemical ionization mass spectrum of butyl nitrate is suggested to be the oxygen base HOHNO-and was confirmed by calculation at the 4-31 le~e1.l~' Hydrazoic acid in solution in nitric acid at 97 "C decomposes to form a mixture of NZ N20 and NO in a strongly acid-catalysed reaction. The proposed mechanism involves electrophilic attack by NO2+ on hydrazoic acid to form N,ONO which can then fragment to N + 2NO-or dissociate to N3. + N02-.148 The decomposition of nitroamine in concentrated aqueous perchloric sulphuric and hydrochloric acids proceeds by rate-determining nucleophilic attack of water upon the protonated nitroamine to give hydroxylamine and nitrous acid which then react to give dinitrogen Initially homogeneous solutions of hydroxylamine in nitric acid can react to form a two-layer system one a solution of nitrous acid in nitric acid and the other a solution of hydroxylamine in nitric acid.'" Definitive evidence that N20 arises from a symmetric precursor species in the hydroxylamine-nitrous acid reaction over the entire range pH 5-9 has been pre~ented.'~' High-resolution nitrogen n.m.r.spectra have been recorded for a number of fluoronitrogen cations in anhydrous HF solution. The lines in the linear or planar species N=NF+ NOF2+ and F2N=NF+ show .rr-fluoro effects being shifted upfield relative to those in corresponding species with hydrogen alkyl or aryl groups instead of fluorine despite the reduction in electron density on nitrogen.In non-planar species however the nitrogen line moves strongly downfield with fluorination as in NH4+to NH3F+to NF4+,and is described as a a-fluoro effect and is rationalized at least in part by a decrease in electron density on nitr~gen."~ Perfluoroalkyl-N,N-difluorohydroxylamines R,0NF2 have been synthesized by the reaction of per- fluoroalkyl hypofluorites with difluoramine in the presence of alkali metal fluoride^,'^^ and by the Lewis acid-catalysed addition of NF30 to 01efins.'~~ The unexpected directian of the NF,O addition resulting in exclusive formation of the anti-Markovnikov isomer can be rationalized by a stepwise addition of BF3 and NF30 via an RfBF2intermediate.The reaction of dichloramine with hypochlorous acid is general base catalysed the base assisting proton removal from NHC1 as the nitrogen attacks the chlorine of HOCl. The trichloramine formed reacts with dichloramine to generate more hypochlorous acid thus speeding up the decompo- sition. The electrochemical reduction of fluorenone triphenylphosphazine F1=NN=PPh3 in DMF-0.1 M-Bu4NC104is initially a one-electron process which I46 B. W. McClelland L. Hedberg K. Hedberg and K. Hagen J. Am. Cbem. SOC.,1983 105 3789. 147 M. M. Bursey R. L. Cerny L. G. Pedersen K. E. Gottschalk K. B. Torner and T.A. Lehrnan J. Cbem. SOC. Cbem. Commun. 1983 5 17. 14' B. M. Maya and G. Stedman J. Cbem. SOC.,Cbem. Commun.,1983 257. I49 M. N. Hughes J. R. Lusty and H. L. Wallis J. Cbem. SOC.,Cbem. Commun. 1983 261. 150 R. J. Gowland and G. Stedrnan J. Cbern. SOC.,Cbem. Commun. 1983 1038. ''I F. T. Bonner J. Kada and K. G. Phelan Inorg. Cbem. 1983 22 1389. 152 J. Mason and K. 0. Christe Inorg. Cbem. 1983 22 1849. I53 W. Maya D. Pilipovich M. G. Warner R. D. Wilson and K. 0.Christe Inorg. Chem. 1983 22 810. I54 R. D. Wilson W. Maya D. Pilipovich and K. 0. Christe Inorg. Cbem. 1983 22 1355. I55 V. C. Hand and D. W. Margerum Inorg. Chern. 1983 22 1449. C Si,Ge Sn,Pb; N P As Sb Bi 103 affords the corresponding radical anion F1=NN=PPh3T.This radical anion is unstable on the cyclic voltametric time-scale and decomposes by N-P bond fission to give PPh and the 9-diazofluorene anion radical F1N2T which then can react rapidly with either the starting material or itself to give a stable dimeric diar1i0n.l~~ The photolysis of CF,CF2N=NCF2CF3 with S2C12 at 0 "C affords the first example of a thiadiaziridine CF,CF2N-S-NCF2CF3 but only in 5% ~ie1d.l~' Poly(su1phur nitride) can be synthesized electrochemically in liquid SO2 from cyclopenta- azathenium chloride S5N5C1.15* 6 Phosphorus and Arsenic Probably the most exciting developments occurring in this area of chemistry involve compounds with multiple bonds. Syntheses of compounds containing P=P P=As P=Sb and As=As double bonds have been described.The method devised by ~owley'~~-'~~ employs DBU (1,5-diazabicyclo[5.4.O]undec-5-ene)as a dehy-drohalogenating agent between a silylmethyl Group V element dichloride (Me3Si)2CHMC12 (M = P As or Sb) and the 2,4,6-tri-t-butylphenylphosphine or arsine yielding the derivatives (70). The diaminodiphosphine (Bu'M~~S~),N-P=P-N(S~M~~BU~)~, was obtained by the reaction of (Bu'Me2Si),N-PC12 with either Bu'Li or lithium X-Ray crystallographic studies have been carried out on the latter compound and on the P=As and As=As homologues of (70). The P=P bond in the aminodiphosphine is similar to that in H M=M' But M=M'= PorAs \/ Me,Si-C M = PM' = As or Sb / Me,Si (70) previous examples whilst both the P=As and As=As bond distances are consistent with multiple-bond formation.Treatment of the diaryldiphosphene ArP= PAr (Ar = 2,4,6-But3C6H2) with elemental sulphur affords the monosulphide ArP(S)=PAr whose structure has been confirmed by X-ray analysis (P=P distance is only 0.2 longer than in ArP=PAr). The reaction is reversed by treatment with HMPTA but isomerization to the thiadiphosphirane ArP-S- PAr occurs both photochemically and thermall~.'~ Reaction of (Me3Si),P=P(SiMe3) with anhydrous HC1 gives (71) whereas excess HBF,.Et,O affords (Me,Si),CPH,BF,. In contrast complete P=P bond cleavage occurs when the diaryldiphosphene ArP=PAr is treated with HCl 156 D. E. Herbranson F. J. Theisen M. D. Hawley and R. N. McDonald J. Am. Chem. SOC.,1983,105,2544. I57 R. C. Kumar and J. M. Shreeve J.Chem. SOC. Chem. Commun. 1983 658. 158 A. J. Bannister Z. V. Hauptman and A. G. Kendrick J. Chem. SOC.,Chem. Commun. 1983 1016. 159 A. H. Cowley J:E. Kilduff S. K. Mehrotra N. C. Norman and M. Pakulski J. Ghem. Soc. Chem. Commun. 1983 528. 160 A. H. Cowley J. G. Lasch N. C. Norman M. Pakulski and B. R. Whittlesey J. Chem. SOC.,Chem. Commun. 1983 881. 161 A. H. Cowley J. G. Lasch N. C. Norman and M. Pakulski J. Am. Chem. SOC.,1983 105 5506. 162 E. Nieke R. Ruger M. Lysek S. Pohl and W. Schoeller Angew. Chem. Znt. Ed. Engl. 1983 22 486. 163 M. Yoshifuji K. Shibayama N. Inamoto K. Hirotsu and T. Higuchi J. Chem. SOC.,Chem. Commun. 1983. 862. P. G. Harrison and the cations (72) (initially) and (73) (on warming) are formed with HBF4.Et20.Ia Not surprisingly diphosphenes and diarsines have been employed as ligands towards transition metals.Unlike the complex (74) in which the 7r-electrons of the P=P double bond are donated to the only the n-electron pairs on phos- phorus are used in complexes (75),16' (76),166(77),167and (78).16' In the complex ' [Fe(CO),p-Fe(CO),](ArP=PAr) (Ar = 2,4,6-But3C6H20) the diphosphene func- tions in both ways simultaneously.168 The 7 '-diarsene-chromium complex (79) has also been chara~teri2ed.I~~ Similar complexes with diaminodiphosphene (80)and M = Fe; n = 4 M = Ni; n = 3 (77) CH(SiMe3)2 As=As / / I 2,4,6-But3C6H2 Cr(CO) (79) 164 A. H. Cowley J. E. Kilduff N. C. Norman M. Pakulski J. L. Atwood and W. E. Hunter J.Am. Chem. SOC.,1983 105 4845. 165 J. Borm L. Zsolnai and G. Hutner Angew. Chem. Znr. Ed. Engl. 1983 22 977. 166 K. M. Flynn N. M. Olmstead and P. P. Power J. Am. Gem. SOC.,1983 105 2085. I67 A. H. Cowley J. E. Kilduff J. G. Lasch N. C. Norman M. Pakulski F. Ando and T. C. Wright J. Am. Chem. SOC.,1983 105 7751. 168 K. M. Flynn H. Hope B. D. Murray M. M. Olmstead and P. P. Power J. Am. Chem. SOC.,1983 105 7750. 169 A. H. Cowley J. G. Lasch N. C. Norman and M. Pakulski Angew. Chem. Int. Ed. Engl. 1983.22,978. C Si Ge Sn Pb; N P As Sb Bi 105 (8l) aminophosphinine (82) and (83) aminoarsinidine (84) and (85),"' 'naked' phosphorus atoms (86),17*diphosphorus (:PEP:) (87),'72 and di-t-butylarsanediyl (88),'73ligands have been synthesized and in most cases characterized structurally.(CO),Fe N( SiMe,) N( SiMe,) N(SiMe,) \/ P=P P P=P / 6 I ".\ (Me3Si),N /L Fe(CO) (Me,Si)2N /L Cr(CO) (co),c~ ICr(CO) (80) (81) (82) Me,Si)2 N N(SiMe,) N(SiMe,) N( SiMe,) / I I P-Cr,( CO),=P As As .;i ';c / -A / -\ (C0)2Cr Cr(CO) (CO),Cr -%Cr(CO) (CO),Fe WCO) (83) (84) (85) /ML. P= But nP / (CO),co -Co(CO) M=As 1 .. \ L,M = (CO),Cr COCO But L,M = (CO),W L M = ( $-C,H,)M~I(CO)~ (88) (87) The major product from the reaction of ( Me3Si),CLi with (Me Si),CPCl,/ (2,4,6-t- Bu3C6H2)PC12 mixtures is the new phospha-alkene (89).'74 Phospha-alkenes and -alkynes exhibit different modes of bonding in the transition-metal complexes 7'-bonding is observed in the complexes (90) and (91),175 T2-bonding in the R CPh2 But \/ \CFP / I Me,Si Pt r;t Ph,C=P/ \P=CPh Ph,C=Pk \RP=CPh RR (91) (90) R = mesityl R Bu' \ Ph,C=P./ CH(SiMe,) Ph2 P '&\PPh Ph 2 P-9p" Me P / \P II I H2C\C/CH H2CyCH2 / Ni-c II /\ /\ Me CH,PPh Me CH,PPh Me,P \CH(SiMe,) (92) (93) (94) K. M. Flynn B. D. Murray M. M. Olmstead and P. P. Power J. Am. Chem. SOC.,1983 105 7460. H. Lang L. Zsolnai and G. Huttner Angew. Chem. Znt. Ed. Engl. 1983 22 976. H. Lang L. Zsolnai and G. Huttner Angew. Chem. Int. Ed. Engl. 1983 22 976. 170 171 172 173 M Luksza S. Himmel and W. Malisch Angew. Chem. Znt. Ed. Engl. 1983 22,416. 174 A. H. Cowley J. E. Kilduff M. Pakulski and C. A. Stewart J. Am. Chem.SOC.,1983 105 1655. I75 S. I. Al-Resayes S. I. Klein H. W. Kroto M. F. Meidine and J. F. Nixon J. Chem. SOC.,Gem. Commun. 1983 930. P. G. Harrison complexes (92) (93) and (94),'753'76 whilst an T2-bridging mode occurs in the complexes (95) and (96).'77 Ph-P=C P( Ph)SiMe / 0 \ N-R I SiMe (95) (96) (97) 1,3-Diphosphapropenes (97) are obtained from the reaction of phenyl- bis(trimethylsily1)phosphane with isocyanide dichlorides RN=CC12.17' The first stable phosphaketene has been synthesized according to the route shown in Scheme 22.'79Flash vacuum pyrolysis of the diphosphetanes (98) affords the (iminomethyl- idene)phosphines (99) (Scheme 23).'*' Treatment of (Me3Si),N-P=NSiMe3 with 0 Scheme 22 the sterically hindered lithium reagent 2,4,6-tri-t-butylphenyl-lithium and 2,2,6,6-tetramethylpiperidine hydrochloride leads to the formation of (loo) the first ther- mally stable example of a compound with the C-P=N skeleton.'8' R I P Ph-N=C /\,C=N-Ph 2R-p=C=N-ph P I R Scheme 23 Bu' BulQ P=N SiMe, Bu' ( 100) I76 A.H.Cowley R. A. Jones C. A. Stewart and A. 1. Stuart J. Am. Chem. SOC.,1983 105 3737. I77 G. Becker W. A. Henmann W. Kalcher G. W. Kriechbaum C. Pahl C. T. Wagner and M. L. Ziegler, Angew. Chem. Int. Ed. Engl. 1983 22 413. R. Appel P. Knoch B. Laubach and R. Severs Chem. Ber. 1983 116 1873. I79 R. Appel and W. Paulen Angew. Chem. Int. Ed. Engl. 1983 22 785. I80 C. Wentrup H. Briehl G. Becker G. Uhl H. J. Wessely A. Maquestiau and R.Flamman J. Am. Chem. SOC.,1983 105 7194. V. D. Romanenko A. V. Ruban and L. N. Markovski J. Chem. Soc. Chem. Commun. 1983 187. 107 C,Si Ge Sn Pb; N P As Sb Bi A few papers describing phosphorus ylide chemistry are worthy of note. Theoreti- cal studies for the phosphonium cyclopropylide H3 P=C(CH2)2 show that the ground-state equilibrium geometry has a pyramidal carbanion centre.lB2 The triethyl- amine-catalysed reaction of dimethylzinc with (CF,),PH gives high yields of the monomeric phosphorus(I1) ylide CF3P=CF2 which is stable as a gas at 100 "C or liquid at -78 OC.lS3 Amongst the crystal structure determinations are those of the ylides Ph,P=C( SPh)SePh,lB4 which has a planar [PCSSe] skeleton Ph P=C(CH2) ,IB5 in which the approximately tetrahedral onium centre is inclined to the neighbouring plane of the puckered cyclobutane ring Ph,P=C(PPh2)2,186 which again has a planar [P=CP2] skeleton and (Me2N)3P=C=P(NMe2)3,187 which is linear at the central carbon atom.The pyrolysis of the trialkyldibromo- arsorane (Me SiCH2),AsBr2 under reduced pressure yields the (bromomethyl)arsane (Me3 SiCH2)2AsCH2 Br via the intermediate formation of Br( Me SiCH2)2A~=CH2.188 The gas-phase ion-molecule chemistry of H2 P- studied by the flowing after-glow technique has shown that reaction with N20 C02,OCS CS2 02,NO2,SO2,MeX and Me3SiCl to yield a variety of ion-products arises from nucleophilic attack of H2P- on the neutral molecule followed by intramolecular proton transfer and/or expulsion of a neutral fragrnent.lB9 Phosphenium ions react with dienes to form the corresponding 3-phospholenium ions as the tetrachloraluminates (Scheme 24).190*191 Scheme 24 Tetraphenylfluorophosphorane can exist in at least three different forms including an ionic monomer a molecular monomer and a dimer.192 Low-temperature limiting 19 F and 31Pn.m.r. spectra suggest that the ground-state geometry of the fluxional phosphorane Me(CF3)3 PH has two axial CF groups on a trigonal-bipyramidal frarne~0rk.I~~ In spite of the steric crowding present in the silylmethylphosphine Ph,PC(SiMe,) readily forms phosphonium salts and also the ylide MePh P=C( SiMe3)2. Methanol cleaves trimethylsilyl groups successively but with decreasing ease giving finally Ph2MeP.194 M.A. Vincent H. F. Schaeffer A. Schier and H. Schmidbaur J. Am. Chem. SOC.,1983 105 3806. I83 A. B. Burg Inorg. Chem. 1983 22 2573. 184 H. Schmidbaur C. Zybill C. Kriiger and H. J. Kraus Chem. Ber. 1983 116 1955. H. Schmidbaur A. Schier and D. Neugebauer Chem. Ber. 1983 116 2173. 186 H. Schmidbaur U. Deschler and B. Milewski-Mahrla Chem. Ber. 1983 116 1393. I87 R. Appel U. Baummeister and F. Knoch Chem. Ber. 1983 116 2275. I88 A. Meyer A. Hartl and W. Malisch Chem Bet. 1983 116 348. I89 D. R. Anderson V. M. Bierbaum and C. H. Dehy J. Am. Chem SOC.,1983 105 4244. C. K. SooHoo and S. G. Baxter J. Am. Chem. SOC.,1983 105 7443. 191 A. H. Cowley R. A. Kemp J. G. Lasch N. C. Norman and C. A. Stewart J. Am. Chem. Soc. 1983 105 7444. 192 S.J. Brown and J. H. Clark J. Chem. SOC.,Chem Commun. 1983 1256. 1Y3 L. V. Griend and R. G. Cavell Inorg. Chem. 1983 22 1817. I94 C. Eaborn N. Retta and J. D. Smith J. Chem. Soc. Dalron Trans. 1983 905. 108 P. G. Harrison The adduct H3N.PF5 obtained either from the two components or (better) from HF and (F2P=N)3 has a slightly distorted octahedral geometry at phosphoru~.'~~ The structures of S(PF2)2 Se(PF,), and PF2(SMe) have all been determined in the gas phase by electron diffraction. For the latter three conformations fit the data equally well.'96 Phosphorus(m) acid reacts rapidly with S(PF2)2 to give PHO(OPF2)2 and then more slowly to give P(OPF2),. Reaction with diorganophosphites affords P(OR)2(OPF2) whilst phosphoric acid and other hydroxy-derivatives .of phos- The phorus(v) give difluoroph~sphino-esters.'~~~'~~reaction of bis(penta-methylcyclopentadieny1)fluoroarsine with BF3 affords the bis(pentamethylcyc1o- pentadieny1)arsenium cation which exists as an angular ~andwich.'~~ Tris(pheny1thio)arsine consists of discrete molecules with C3 symmetry.200 Numerous papers describe compounds containing direct phosphorus-phosphorus bonds.The reaction of Pri,NPC12 with magnesium metal in boiling thf gives either the diphosphine (101) or the cyclotetraphosphine (102) depending on the mole Pr' N NPr', \/ Pr' N NPr' P-P \/ I1 P-P c1/p-p\cl Pr' N ' 'NPr' (1011 (102) ratio of the reactants.20' The diphosphabutadiene (103) has been obtained via the routes shown in Scheme 25.202Unsymmetrical tetra-alkyldiphosphanes have been synthesized by the scrambling of the symmetrical diphosphanes in CH2C12.203 The eight-membered [P4C4] heterocycle (104) has been obtained in a one-step reaction II0"C /OSiMe3 Me3Si -P=C /OSiMe3 + C2C16 -c1 -P=C -Me SiCl \CMe -c2& 'CMe +150°CI-Me,SiCI OSiMe, I 0 (Me,Si),P-P(SiMe3)z + C1-C / ____* -2 Me3SiCI I \ CMe OSiMe (103) Scheme 25 I95 W.Storzer D. Schornburg G. V. Roschenthaler and R. Schmutzler Chem. Ber. 1983 116 367. 196 S. E. J. Arnold G. Gundersen D. W.H. Rankin and H. E. Robertson J. Chem. Soc. Dalton Trans. 1983 1989. I97 E. A. V. Ebsworth G. M. Hunter and D. W. H. Rankin J. Chem. SOC.,Dalton Trans. 1983 1983. I98 E. A. V. Ebsworth G. M. Hunter and D.W.H. Rankin J. Chem. SOC.,Dalton Trans. 1983 245. I99 P. Jutzi T. Wippermann C. Kriiger and H. J. Kraus Angew. Chem. Int. Ed. Engl. 1983 22 250. 200 G. C. Pappalardo R. Chakravorly K. J. Irgolic and E. A. Meyers Acra Crysrallogr. 1983 C39 1618. 201 P. B. King N. D. Sadanani and P. M. Sundaram J. Chem. Soc. Chem. Commun. 1983,477. *02 R. Appel V. Barth and F. Knoch Chem. Ber. 1983 116 938. 203 A. A. M. Ali and R. K. Harris J. Chem. Soc. Dalton Trans. 1983 583. C,Si Ge Sn Pb; N P As Sb Bi 109 from 3,4-dimethyl- 1-phenylphosphole and is a very flexible 'crown' ligand being able to adapt its shape to the stereochemical requirements of complexed metals.204 Three-membered rings containing P- P bonds have been prepared by various methods [P2S] rings have been prepared via the reaction of the diphosphene (Me3Si)2N-P=P-N(SiMe3)2 with elemental sulphdo5 or the reaction of mesityl- dichlorophosphine sulphide with magnesium and cyclotelluradiphos- phanes result from reaction of Bu'PC12 or (Bu'PCI) with Na2Te.A four-membered telluratriphosphacyclobutane results from the reaction of Bu'P( SiMe3)2 with ele- mental tell~rium.~~' Tris-t-butyldiphosphastibacyclopropaneis formed in the [2 + 13 cyclocondensation of KBu'P- PBu'K with BU~S~C~,.~~* The spirocycle ( 105) is formed similarly as a mixture of isomers but only in ca. 5% yield.209 The four- membered triphosphaetanones ( 106) readily eliminate CO on exposure to a reaction which is also exhibited by the five-membered tetraphosphaolan-5-one ( 107).,' The linear tetraphosphane Me,SiBu'P-(Bu'P),-PBu'SiMe, is remark- ably stable towards disproportionation and exists in only one conformation in Me MeMe Me 0 But Ph ,PBu' C $$-'k$ph Bu'P,ICI II \ P-P /But ' Bu'-P /\,P-Bu' Bu'P,1 ,PBu' s YI Bu'P' \PBu' P C I II PhMPh R 0 Me MeMe Me (1 05) ( 104) (107) (104) solution below -30 0C.212 The branched tetraphosphane P( Bu'PH), has been iso- lated ir pure form from the reduction of P(Bu'PBr)3 with LiAIH4.Because of the chirality of the Bu'PH groups the compound forms two diastereoisomers in a ratio of ca. 3 1 Pi-donors or acceptors exert a considerable effect on the bond lengths in substituted tetraphosphabicyclo[ 1.1.O]butanes ( 108). The central bond like bicyclo[ 1.1.O]butane possesses double bond character.,I4 P,Me3 has been shown by P{* H} n.m.r.to possess the 3,5,7-trimethyltricyclo[2.2.1.02*6]heptaphosphane structure ( 108) (two isomers).215 The different reactivity of the related cage compound ( 109) has been discussed in terms of a simple MO scheme.216 The triorganononaphos- phanes P9R3 (R = Pr' or Bu') have been synthesized by the reaction of (PriP)4 204 J. Fischer A. Mitschier F. Mathey and F. Mercier J. Chern. SOC. Dalton Trans.. 1983 841. 205 E. Niecke and R. Riiger Angew. Chem. lnt. Ed. Engi. 1983 22 155. 206 M. Yoshifuji K. Ando K. Shibayama N. Inamoto K. Hirotsu and T. Higuchi Angew. Chem. lnt. Ed. En& 1983 22 418. 207 W. W. Du Mont T. Severengiz and B. Meyer Angew. Chem. In?. Ed. EngL 1983 22 983.208 M. Baudler and S. Klautice 2. Nuturforsch. Ted B 1983 124. 209 M. Baudler and W. Leonhardt Angew. Chem. Int. Ed. Engl. 1983 22 632. 210 R. Appel and W. Paulen Chem. Ber. 1983 116 2371. 21 I R. Appel and W. Paulen Chem. Ber. 1983 116 109. 212 M. Baudler G. Reuschenbach and J. Yahn Chem. Ber. 1983 116 847. 213 M. Baudler J. Hellrnann and T. Schmidt Z. .Nuturforsch. Ted B 1983 38 537. 214 W. W. Schoeller and C. Lerch Inorg. Chem. 1983 22 2992. 215 M. Baudler and T. Pontzen 2.Nuturforsch. Teil B 1983 38 955. 216 R. Gleiter M. C. Bohm M. Eckert-Maksic W. Schafer M. Baudler Y. Aktalay G. Fritz and K. D. Hoppe Chem. Ber. 1983 116 2972. P. G. Harrison with PCl or the dehalogenation of a mixture of Bu'PCl and PCl with magnesium metal respectively.For the preparation of the methyl and ethyl homologues the latter reaction may be modified by employing organylcyclophosphanes instead of RPCl,. According to 31P n.m.r. data the nonaphosphanes possess a skeleton analogous to that of deltadecane (110).2'7 The thermolysis of hepta- and nona- phosphanes leads to the formation of P,,Pr' and PI3Pris the latter of which was proposed to have structure (1 1 1) on the basis of n.m.r. data.218 The largest phosphorus cage obtained is the hexadecaphosphide dianion (1 12) (as its lithium salt and octa-thf solvate) from the reaction of white phosphorus with lithum dihydrogenphosphide in boiling thf.219 Me dP\ 'p P \P-P ye/ 'P' Gas phase pyrolysis of the cyclic phosphonite (1 13) generates the monomeric metaphosphonite (1 14) which is trapped by an intramolecular reaction with the adjacent biphenyl group to afford (1 15).220 The mixed-ligand phosphorane ( 116) represents the least distorted example of rectangular pyramidal geometry so far examined being 93-0% displaced from trigonal bipyramidal.221 The reaction of C02 with Me(CF3)3 PNMe yields the neutral six-co-ordinated carbamate Me(CF3)3P0,CNMe2.In solution the CF groups are equivalent but at low tem- peratures the compound exists in the solid-state form.222 217 M. Baudler Y. Aktalay K. Kazmierczak and J. Hahn 2.Naturforsch. Teil B 1983 38 428. 218 M. Baudler Y. Aktalay V. Arndt K. F. Tebber and M. Feher Angew. Chem. Znt. Ed. Engl. 1983 22 1002. 219 M.Baudler and 0. Exner Chem. Ber. 1983 116 1268. 220 S. Bracher J. I. G. Cadogan 1. Gosney and S. Yaslak J. Chem. Soc. Chem. Commun. 1983 857. 22 I A .C. Sau J. M. Holmes R. 0.Day and R. R. Holmes Inorg. Chem. 1983 22 1771. 222 R. G. Cavell and L. V. Griend Inorg. Chem. 1983 22 2066. C Si Ge Sn Pb; N P As Sb Bi C1 (116) Reaction of (Pr',N),P(O)H with Mo(CO) proceeds via deamination and the formation of the complex (P~',NPO),MO~(CO)~, which contains a central [P404M02] cage structure.223 Both P4S3 and P,Se3 have been used as ligands in such complexes as {Ir(P4S3)(PPh3)C1(CO)}~z~4 and (np3)M(P4X3) (M = Ni X = S or Se; M = Pd X = S; np = tris{2-(diphenylphosphino)ethyl}amine).22' In the reac- tion of P4S3 and P4Se3 with [RhCl(cod)] in the presence of triphos {l,l,l- tris(diphenylphosphinomethyl)ethane} cleavage of the cage takes place and the complexes [(triphos)~h(~,~,)1.~,~, (X= s or Se) are isolated.226 The chemistry of P-N bonded compounds is extremely rich.The silylaminophos- phines (Me3Si),NPRPr' (Me3Si)*NPRH and [(Me3Si),NJ2PCHZR have been obtained by the Grignard method from the appropriate chlorophosphine. The P-H phosphines appear to be formed by a process in which the Grignard reagent functions as a reducing agent with the elimination of propene. Alternatively they can be prepared by reduction with LiAlH,. Treatment of the [(Me3Si),N],PCH2R deriva- tives with Me3SiN affords the phosphinimine [( Me,Si),N],PMe~NSiMe,. Similar phosphinimines can also be obtained by the reaction of the phosphonium salts [(Me Si) N],PMe2+I- with alkyl-lithium reagents.With CCl, the [( Me,Si) N],PCH,R compounds gave a mixture of (Me3Si),NPCl( Me,SiCHR)=NSiMe and (Me3Si),NPC1( CH,R)=NSiMe,. The reaction of CC14 with the sterically-congested mesityl derivative (Me3Si),NPRCHzSiMe3 (R = mesityl) unexpectedly afforded the four-membered [P,N,]ring compound (1 17) which on heating under a dynamic vacuum dissociates to the monomeric three-co-ordinated iminomethylenephosphorane( 118). This com- pound (1 18)is stable at room temperature for a short time but reverts to (1 17) after a few days.229 Papers describing P-N rings and cages abound. (5,10,15,20-Tetraphenylpor-phinato)dichlorophosphorus(v) chloride has been synthesized and its electro- 223 E.H.Wong M. M. Turnbull E. J. Gabe F. L. Lee and Y. Le Page J. Chem. SOC.,Chem. Commun. 1983 776. 224 C. A. Ghilardi S. Midollini and A. Orlandini Angew. Chem. Znt. Ed. Engl. 1983 22 790. 225 M.Di Vaira M. Peruzzini and P. Stoppioni Znorg. Chem. 1983 22 2196. 226 M.Di Vaira M.Peruzzini and P. Stoppioni J. Chem. SOC.,Chem. Commun. 1983 903. 227 H. R. O'Neal and R. H. Neilson Znorg. Chem. 1983 22 814. 228 B. L. Li J. S. Engenito R. H. Neilson and P. Wisian-Neilson Inorg. Chem. 1983 22 576. 229 2. M. Xie and R. H.Neilson Orgonometallics 1983 2 1406. P. G. Harrison R Me (1 17) (1 18) chemistry reveals that it undergoes two reductive processes at the porphorin ring.230 The structure of the related (porphinato)phosphorus( v) hydroxide dihydrate shows a distorted octahedral co-ordination for phosphorus which is displaced 0.09 8 from the mean plane of the pyrrole nitrogen atoms and a non-planar porphyrin ring.231 The concentration dependence of the 31P n.m.r.chemical shift of cyclenphosphine oxide (1 19) indicates that a monomer-dimer equilibrium is operating in CDC13 solution.232 Cyclenphosphorane ( 120) readily adds two equivalents of BH3 to afford the bis-adduct ( 121).233 (1 19) (1 20) (121) The cyclophosph(~rr)azanes (CIPNEt), C12P4(NEt), and C12P-NEt-PC12 are formed by suitable variation of the stoicheiometry of a mixture of PCl and ethyl- amine hydrochloride in refluxing sym-tetrachloroethane. 0x0 derivatives are also formed in low yields or by reaction with oxygen or DMS0.234In contrast to the reaction of propenyl-lithium with (N3P3F6) no evidence for degradation reac- tions uia anionic attack on the alkene centre was observed in the reaction of ( 1-1ithioalkoxy)ethylenes.Rather reaction proceeds smoothly to yield N3P3F,- [C(OR)=CH2] (n = 1 or 2) derivative^.^^' Similarly the reactions of enolate anions of acetaldehyde acetone and acetophenone lead exclusively to enol-substituted phosph( ~~~)azenes.*’~’~~’ Reaction of (P3 N3 Cl,) with methyl-lithium leads to the formation of acyclic ‘ring-opened’ phosphazenes and only small amounts of monomethyl- and dimethyl-substituted cyclotriph~sphazenes.~~~ Hexaphenoxy-cyclo(triphosphazene) polymerizes in the ion source of a mass spectrometer.239 The two arsazenes [(CF,),AsN] (n = 3 or 4) are produced by refluxing [(CF,),AS(C~)(S~M~,>]~ in n-hexane or n-heptane.The molecular symmetry of the tetra-arsazene approximates to 4.240 230 C. A. Marrese and C. J. Carrano Inorg. Chem. 1983 22 1858. 23 1 S. Mangani E. F. Meyer D. L. Cullen M. Tsutsui and C. J. Carrano Inorg. Chem. 1983 22 400. 232 J. E. Richman and J. J. Kubale J. Am. Chem. SOC.,1983 105 749. 233 J. M. Dupart S. Pace and J. G. Riess J. Am. Chem. SOC.,1983 105 1051. 234 D. A. Harvey R. Keat and D. G. Rycroft J. Chem. SOC.,Dalton Trans. 1983 425. 235 C. W. Allen and R. P. Bright Inorg. Chem. 1983 22 1291. 236 K. Ramachandran and C. W. Allen Inorg. Chem. 1983 22 1445. 237 P. J. Harris M. A. Schwalke V. Liu and B. L.Fisher Inorg. Chem. 1983 22 1812. 238 P. J. Harris and C. L. Fadeley Inorg. Chem. 1983 22 561. 239 M. Gleria G. Audisio P. Traldi S. Daolio and E. Vecchi J. Chem. SOC.,Chem. Commun. 1983 1380. 240 R. Bohra H. W. Roesky J. Lucas M. Noltemeyer and G. M. Sheldrick .I.Chem. SOC.,Dalton Trans. 1983 1011. C Si Ge Sn Pb; N P As Sb Bi 113 Related to the phosphazenes are P-N-S heterocycles such as (122) formed by the reaction of (Ph2PN),NSCl with Ph3Sb in acetonitrile?’ (123) formed by the thermal conversion of (122) at 150-185 0C,242 and (Ph2PN)2NSI which contains a six-membered [P2SN3] ring,243 as well as the complex (124).244 Other ring-systems studied include the azadiphosphirane (125),245and the azatriphosphetidines (126),245 the 1,3,2-diazaphosphetidin-4-0ne(127),246 the 1,3,2,4-diazadiaphosphetidin-2-oxide (128),246 the 1,2,4,3-thiadiazaphosphetidine-l,l-dioxide(129),246 and spiro systems such as (130),247(131),247 and (132).248 \ Me R R2 I I I N R~-P-NR’ R2-P-p=NR’ /\ 0% /N\ \/ II o=C /P-NEt /p\ /P-NEt2 R2’ P*NR1 R ‘N=P-NR l N Y 1 I R2 Me R 7 Antimony and Bismuth Three papers have reported the synthesis and properties of tetraorganodibismuthines R2Bi-BiR,.The general method is to generate the diorganobismuth sodium inter- mediate which is then treated with 1,2-dichloro- or 1,2-dibromo-ethane all in liquid ammonia. The dibismuthines are red in solution and most are red in the neat liquid or solid. However the tetramethyl- and tetra-iso-butenyl-dibismuthines and (133) 24 1 T.Chivers M. N. S. Rao and J. F. Richardson J. Chem. Soc. Chem. Commun. 1983 186. 242 T. Chivers M. N. S. Rao and J. F. Richardson J. Chem. SOC.,Chem. Commun. 1983 702. 243 T. Chivers M. N. S. Rao and J. F. Richardson J. Chem. SOC.,Chem. Commun. 1983 700. 244 0.J. Scherer J. Kerth and M. L. Ziegler Angew. Chem. Znr. Ed. Engl. 1983 22 503. 245 E. Niecke R. Riiger B. Krebs and M. Dartmann Angew. Chem. Znt. Ed. Engl. 1983 22 552. 246 E. Fluck and H. Richter Chem Ber. 1983 116 610. 247 A. Schmidpeter M. Mayibi P. Mayer and H. Tautz Chem. Ber. 116 1983 1468. 248 R. 0.Day A. Schmidpeter and R. R. Holmes Inorg. Chem. 1983 22 3696. 114 P. G. Harrison freeze to blue solids. The structure of tetraphenyldibismuthine has been deter- mined.249-25 1 Several new vinyldistibanes have been prepared by largely similar methods.These compounds also exhibit thermochromism existing as yellow liquid- phases but freezing as either yellow orange or violet solids.252 Tetramethyldistibane reacts with equimolecular amounts of di-p-tolylditelluride to afford the first Te-Sb bonded compound MeC,H,Te-SbMe .253 The structure of the complex (C,H,)Fe(CO)( PMe3)SbBr2.PMe3 has been determined.254 The main interest in antimony and bismuth halide chemistry lies with several structural determinations although U.V. photoelectron spectra for SbF and the bismuth trihalides,,, and the 35Cl and 121*123Sb n.q.r. frequencies for a number of adducts of antimony(v) chloride have been reported.256 In the solid chain structures are extremely common and are formed by halogen bridging which can be weak or strong.Such chain structures are found in the antimony fluoride [SbF3]3[SbF5],257 and in [IBr2][Sb2F [1Br0.75C10.251[SbC161~58 [Et NH][SbC1,],259 [MeNH3]3[SbC16],259 [Ph3SbC12][SbC13],260 [Ph3SbC1][SbC16],260 and the 4,4’-bipyridyl complex of SbC15 Alternatively as in the 2,2’-bipyridyl complex of SbC15,261 and the compounds A12Sb2112262 halogen and [(C5H5)2Fe]4[Bi4Br,6],z63 bridging produces small cluster species. Of the related complexes of BiCl, BiC13 (pptu) (pptu = 1-phenyl-3-( 2-pyridyl)-2-thiourea} and [BiC13 (deimdt),] (deimdt = N,N’-diethylimidazolidine-2-thione), the former is monomeric whilst the latter is a chlorine-bridged dimer.264 Similarly the structures of several oxide and oxy-acid derivatives have been determined.[SbO,] octahedra are present in monoclinic AsSbO ,265 HSb305,266 and the compounds MSb,0,3 (M = H30 Na or K).267 Octahedral co-ordination for 24Y A. J. Ashe E. G. Ludwig and J. Oleksyszyn Organometallics 1983 2 1859. 250 H. J. Breunig and D. Muller 2. Naturforsch. Ted B 1983 38 125. 25’ F. Calderazzo A. Morvillo G. Pelizzi and R. Poli J. Chem. Commun. 1983 507. 252 A. J. Ashe E. G. Ludwig and H. Pommerening Organometallics 1983 2 1573. 253 W. W. Du Mont T. Severengiz and A. J. Breunig Z. Naturforsch. Teil B,38 1983 1306. 254 H. A. Kaul D. Greissinger W. Malisch H. 0. Klein and U. Thewalt Angew. Chem. ~ni.Ed. Engl. 1983 22 60. 255 I. Hovak and A. W.Potts J. Chem. SOC.,Dalton Trans. 1983 635. 256 J. Rupp-Bensadon and E. A. C. Lucken J. Chem. SOC.,Dalton Trans. 1983 19. 257 W. A. S. Nandana J. Passmore D. C. N.Swindells P. Taylor P. S. White and J. E. Vekris J. Chem. SOC.,Dalton Trans. 1983 619. 258 T. Birchall and R. D. Myers Inorg. Chem. 1983 22 1751. 259 U. Ensinger W. Schwarz and A. Schmidt Z. Naturforsch. Teil B,1983 38 149. 260 M. Hall and D. B. Sowerby J. Chem. SOC.,Dalton Trans. 1983 1095. 26’ A. Lipka Z. Naturforsch. Teil B 1983 38 1615. 262 S. Pohl Z. Naturforsch. Teil B 1983 38 1539. 263 A. L. Rheingold A. D. Uhler and A. G. Landers Inorg. Chem. 22 1983 3255. 264 L. P. Battaglia and A. B. Corradi J. Chem. SOC.,Dalton Trans. 1983 2425. 265 D. Bodenstein A. Brehm P.G. Jones E. Schwarzmann and G. M. Sheldrick Z. Naturforsch. Teil B 1983 38 901. 266 G. Jager P. G. Jones G. M. Sheldrick and E. Schwarzmann 2. Naturforsch. Teil B,1983 38 698. 267 D. Bodenstein W. Clegg G. Jager P. G. Jones H. Rumpel E. Schwarzmann and G. M. Sheldrick Z. Narurforsch. Teil B 1983 38 1972. C Si Ge Sn Pb; N P As Sb Bi antimony is also found in [Me2P02SbC1]:68 and the Me4Sb ~xinate,*~~ whilst in the sulphate (H30)2Sb2(S04):70 and the phosphates Na(SbF)P04. n H20 and NH4 (SbF) P04.H20,27 the antimony enjoys square pyramidal co-ordination with * the lone pair of electrons occupying the sixth octahedral site. The structure of Bi604(OH)4(C104)6.7H20 contains discrete hexanuclear [Bi604(0H):+] clusters in which the six bismuth atoms have a slightly distorted octahedral arrangement.The co-ordination of each bismuth is basically pseudo-trigonal bipyramidal with the lone pair occupying an equatorial site. However four further contacts to oxygen result in an irregular eight-fold co-ordination polyhedron.272 Antimony is in six-fold co-ordination in the two dithiophosporidate derivatives Sb[S,P(OR),] (R = Me and Pri)273 and the xanthate Sb(SzCOEt)2Br,274 where bromine bridging gives rise to a chain structure. The stereochemistry at bismuth in the [Bi( S2C2(CN),),-] anion an infinite polymeric chain has been described either as a highly distorted octahedron with a stereochemically inactive lone pair or more likely a distorted pentagonal bipyramid in which the lone pair is stereochemically active in an equatorial 2h8 S.Blosl W. Schwarr and A. Schmidt Z. Naturforsch. Teil E 1983 38 143. 269 H. Schmidbaur B. Milewski-Mahrla and F. E. Wagner Z. Naturforsch. Teil B 1983 38 1477. 270 R. Mercier J. Douglade P. G. Jones and G. M. Sheldrick Acta Crystallogr. 1983 C39,145. 27 1 R. Mattes and K. Holz Angew. Chem. Int. Ed. EngL 1983 22 872. 272 B. Sundvall Inorg. Chem. 1983 22 1986. 273 D. B. Sowerby I. Haiduc A. Barbul-Rusu and M. Salajan Inorg. Chim. Acta 1983 68 87. 274 R. W. Gable B. F. Hoskins R. J. Steen E. R. T. Tiekink and G. Winter Inorg. Chim. Acta 1983 74 15. 275 G. Hunter and T. J. R. Weakley J. Chem. Soc. Dalton Trans. 1983 1067.