4 Aluminium Gallium Indium and Thallium BY J. P. MAHER School of Chemistry University of Bristol Bristol BS8 1 TS UK The computer search of the literature for papers related to the chemistry of the title elements has taken the same form as previous years this year yielding just over 4000 references slightly more than for 1993. The proportion of papers abstracted element by element was 71% aluminium 14% gallium 10% indium and 5% thallium. Only a very small amount of this work is reported here the great bulk of chemical applications being ignored. However some applications are very striking none more so than the initial reports from SAGE (the Russian American Gallium Solar Neutrino Experi- ment) where a huge pool (57 tons!) of liquid gallium is being used to trap solar neutrinos to test solar models.’ There has also been a great deal of current interest in the preparation and properties of ‘ITO’ (indium-tin-oxide) films.2 The future always seems to be around the corner for GaAs semiconductors despite many favourable report^,^ though there are numerous methods for producing GaAs and the other related Group 3-5 materials and thin films.4 An interesting new catalytic system for fixing carbon dioxide has been based upon a rare earth phosphonate and triisobutylaluminium catalyst this catalyses the formation of a copolymer with epichlorohydrin.s 1 OrganometallicHighlights Organometallic studies dominate current Group 13 chemical research for gallium and indium this probably has a good deal to do with the aforementioned interest in Group 3-5 materials.This year there were as many references to gallanes and indanes as there were to alanes. Compounds which contain aluminium in various ring systems have been prepared and characterized by spectroscopy or by X-ray diffraction. The compound [Me2M(p2- C,H,S)] (M = Al In) has a four-membered Al,S,-ring Me,Al(p-Me)(p2-‘ 0. L. Anosov et al. Philos. Trans. R. SOC.London A 15,346 1994; also J. N. Abdurashitov Phys. Lett. B 1994 328 234. ’ D. Gallagher F. Scanlan R. Houriet H.J. Mathieu and T.A. Ring J. Mater. Res. 1993 8 3135. J. Travis Science 1993 262 1819. V. Lakhotia J. M. Heitzinger A.H. Cowley R.A. Jones and J.G. Ekerdt Chem. Mat. 1994,6,871;M. A. Khan D.T. Olson and J.N. Kuznia Appl. Phys. Lett. 1994 65 64; M.Kitsunai and T. Yuki Appl. Organometallic Chem. 1994 8 167; D. M. Frigo G. J. M. Veneijden P. J. Reuvers and C. J. Smit Chem. Mater. 1994 6 190; B. Fraser L. Brandt W.K. Stovall H.D. Kaesz S.I. Khan and F. Maury J. Organomet. Chem. 1994 472 317; A.C. Jones J. Auld S.A. Rushworth and G. W. Critchlow J. Cryst. Growth 1994,135,285;S. R. Aubuchon A.T. Mcphail R. L. Wells J. A. Giambra and J. R. Bowser Chem. Mater. 1994 6 82. Z. Q. Shen X. H. Chen and Y.F. Zhang Macromol. Chem. Phys. 1994 195 2003. 41 J.P. Maher C,H,S)AlMe an A1,CS-ring and ((2-C,H3s),A1[p-N(H)C(H)(C6H5),]) ,an Al,N,- ring.6A very unusual Zr-A1 ring with an acetylide bridging between the aluminium and the zirconium is found in the complexes Cp,Zr(p-$ :q2-RCCMe)(p-C=CR)AlMe (R = SiMe, cyclohexyl CMe, or Me); seven-membered hetero-dimetallic Al-Zr and A1-Hf cyclic frameworks showing n-agostic o-ally1 Zr and Hf interactions were also found.7 Reactions of Me,Al with 1,4-dioxa-8-azaspir0[4.5]decane in toluene gave the Al,N,-containing [Me,Al-N(CH,CH),-C-(OCH,),1,.8 A silyl-aminoalane ring is found in [(Me,Si),AlN(H)(SiMe3)]2.9 Cyclo-metallation of olefins and of acetylenes with alkylalanes in the presence of Cp,ZrCl has been shown to give 3-substituted alumina-cyclopentanes and -cyclopentenes.In [Al(CH,C(CH,NH),),(A1(CH3)2)3] both four- and six-coordinated A1 atoms have been observed with the tripodal NH groups serving as both chelating and bridging ligands. The four aluminium atoms all lie in a plane with three forming an equilateral triangle around the fourth central Al a central AlN6 unit of the complex has octahedral symmetry and the other three aluminium atoms are in a tetrahedral environment.The central A1 is connected to the terminal A1 by two bridging nitrogen atoms of the tripodal ligand forming three four-membered rings1 The compound ([(Me2A1),(p-OCH,-2-C,H,S),IAI) also contains four- and six-coordinate alumin- ium centres.' The reaction of [(Me3Si),CH],Al-CH,-Al[CH(SiMe,)2]2with LiCH(PMe,) in the presence of tmeda has been shown to lead to the formation of a five-membered AI,C,P heterocycle the crystal structure determination revealed a strongly bent ring with the P located above the plane of the Al,C so that one A1 is coordinated by the carbanionic C atom and the second one coordinated by one P atom.' Rather more common are the four-membered rings found in the neopentyl compounds [Np,AlN(H)Ph], [Np,AlSNp], and [BiphAlN(H)Ph] (Np = Me,CCH and Biph = bi~henyl).'~ The C-H acidic compounds Me,C-AIR and Me,C-CH,-AlR (R = CH(SiMe,),) have been deprotonated by treatment with LiCH(SiMe,) in the presence of 1,3,5-trimethylhexahydrotriazinane, deprotonation occurring at a methyl group of one of the element-organic substituents.The carbanions which are formed are stabilized by coordination to the unsaturated A1 atoms as four-membered heterocy~les.'~ Bu'Li has been shown to react with the recently synthesized methylene bridged dialuminium compound [R,AlCH,AlR,]2 (R = CH(SiMe,),) in the presence of tmeda by p-elimination forming a three-centre- two-electron Al-H-A1 bonded compound [R,Al(p-CH,)p-H(AlR,] .' Alanes with chain structures have been described.An N-Al-0-A1-N linkage has been found in the aluminoxane [(2-C,H,S),Al.N(Me,)CH2CsH4FeCp]20 which was formed from the reaction of (2-C4H,S),A1.0Et with the hydrated H. Rahbarnoohi R. Kumar M. J. Heeg and J. P. Oliver Organometallics 1994 13 3300. ' G. Erker M. Albrecht C. Kruger M. Nolte and S. Werner Organornetallics 1993,12,4979;G. Erker R. Noe and D. Wingbermuhle Chem. Ber. 1994 127 805. J. B. Hill T. A. Talley W.T. Pennington and G. H. Robinson J. Chem. Crystall. 1994 24 61. J. F. Janik E. N. Duesler and R.T. Paine Chern. Ber. 1993 126 2649. lo U. M. Dzhemilev and A. G. Ibragimov J. Organornet. Chem. 1994 466,l.M. D. Li C. C. Chang S.T. Liu G. H. Lee Y. Wang and S. M. Peng Organometallics 1994 13 1504. R. Kumar V. S. J. Demel M. L. Sierra D.G. Hendershot and J. P. Oliver Organometallics 1994,13,2079. l3 W. Uhl and M. Koch Z. Anorg. Allg. Chem. 1994 620 1427. l4 M. D. B. Dillingham S. J. Schauer J. Byershill W. H. Pennington and G. H. Robinson J. Coord. Chem. 1994 31 283. l5 W. Uhl M. Koch S. Pohl and W. Saak Z. Anorg. Allg. Chem. 1994 620 1619. W. Uhl and M. Layh 2. Anorg. Allg. Chem. 1994 620 856. Aluminium Gallium Indium and Thallium 43 amine.' Under mild conditions Al-A1 bonded tetrakis[bis(trimethylsilyl)methyl] dialane reacts with Et,P+Te- to give R,AlTeAlR (R = CH(SiMe,),) in high yields." In the case of [RMe,AlClAlMe,R]Li (R = 2,3,4,5-tetramethyl pyrrole anion) two Me,RAl units are bridged by the chlorine atom and both pyrrole rings are pentahaptocoordinated to the lithium atom.' The tridentate amine ligand Et,NCH,CH,NHCH,CH,NEt (tetraethyldiethylenetriamine tedtaH) reacts with Me,Al in the appropriate ratios to give either AlMe,(tedta) or Al,Me,(tedta) the A1 being coordinated to the central N or to all three nitrogen atoms respectively." No evidence for n-interactions in Al-N or Ga-N bonds has been found from a study using 'H and 13C NMR and X-ray crystallographic analyses of the compounds mes*GaCl(N(H)Ph}.O.25(hexane),mes;GaN(H)Ph mesA1(N(SiMe3),}, mes*Ga (NHPh), and ClGa(N(SiMe,),} (mes = 2,4,6-Me,C6H, mes* = 2,3,6-Bu',C6H2).The data suggest that any n-interactions in the M-N bonds are rather weak and are of the order of 40 kJ mol- ' The reactions of MgCp with an RZA1C1 compound offer a convenient route to the corresponding Cp2AlR species this method has been used to prepare Cp,AlMe(l) and Cp,AlEt (2).The 'H NMR spectrum of the diethyl ether adduct Cp,AlMe.Et,O (3) provided evidence for small amounts of the ligand redistribution species CpAlMe and Cp3A1.,' When (1) or (3) were reacted with Bu'NC in petroleum ether the ligand redistribution product Cp,Al(C=NBu') (4) precipitated selectively from solution.Cp,Al complexes such as (4) and the isomeric adduct Cp,Al(N=CBu') can be prepared more directly in higher yields from AlCl and MgCp,. An X-ray crystal structural analysis of (4) showed it to be a monomer with C symmetry and the cyclopentadienyl rings coordinated in an q' fashion to the aluminium.* In contrast the decamethyl-aluminocenium ion [AlCpz] +,is a n-stabilized cation with an q5-bonding c~nfiguration.'~ ab initio SCF Calculations of the structural and NMR parameters of this newly discovered aluminocene sandwich complex and of the corresponding bis(q5-dicarbollide)aluminium anion are in good agreement with the experimental data.24 Other interesting alanes are [A1,(p3-8-quinolylimide),(CH3)7(p-OCH,)],formed by oxygen-induced structural transformation of the polynuclear organoaluminium complex [A14(p3-8-quinolylimide),(CH3)8];25the first carbon-phosphorus-alumin-ium cage compounds formed by cyclo-oligomerization of phosphaalkynes with trialkylaluminium compounds;26 and an isolable 'Al"' species (bipy)Al[CH(SiMe,),] which has been characterized unambiguously by EPR and UV-visible spectroscopy and by cyclic voltammetry as an Al"' complex of the bipy radical anion." " R.Kumar H. Rahbarnoohi M. H. Heeg D.G. Dick and J. P. Oliver Inorg. Chern. 1994 33 1103. W. Uhl and U. Schutz Z. Naturforsch. Teil B 1994 49 931. l9 H.D. Hausen J. Todtmann and J. Weidlein J. Organornet. Chem. 1994 466 C1. 2o S.J. Trepanier and S.N. Wang Organometallics 1994 13 2213. " P. J. Brothers R. J. Wehmschulte M.M. Olmstead K. Ruhlandtsenge S. R. Parkin and P. P. Power Organometallics 1994 13 2792. 22 J.D. Fisher M.Y. Wei R. Willett and P.J. Shapiro Organometallics 1994 13 3324. " C. Dohmeier H. Schnockel C. Robl U. Schneider and R. Ahlrichs Anyew.Chem. Int. Ed. Engl. 1993,32 1655. 24 U. Schneider and R. Ahlrichs Chem. Phys. Lett. 1994 226 491. 25 S.J. Trepanier and S.N. Wang Angew. Chem. Int. Ed. Engl. 1994 33 1265. 26 B. Breit A. Hoffmann U. Bergstrasser L. Ricard F. Mathey,and M. Regitz Angew. Chem. Int. Ed. Engl. 1994 33 1491. '' S. Hasenzahl W. Kaim and T. Stahl fnorg. Chim. Acta 1994 225 23. 44 J.P. Maher The first alane-phosphine adduct with C,P,-pentacoordination at aluminium has been described namely Al[o-(Ph,PCH,)C,H,] ,. Trigonal bipyramidal coordination at Al is obtained by two of the anionic phosphines acting as chelating ligands spanning equatorial C-atoms and axial site P-atoms while the third phosphine is only C-bonded. The heavier congeners with Ga In and TI are stereochemically non-rigid molecules in solution.In the solid state the indium complex also has the same C,P,-pentacoordination whereas the gallium and thallium compounds have four- coordinate metal centres (C,P). These observations may be rationalized by assuming less polar Ga-P bonds as compared to AI-P and In-P bonds whilst in TlL the ligand bite is insufficient for either five- or six-coordination.28 As with aluminium there has been a great deal of research carried out on cyclic gallium and indium compounds. Thus dimeric and trimeric 1-(dialky1amino)- 1 -galla-3-cyclopentenes [(C,H6)Ga(NR,)] (x = 2,3) and dimeric 3,4-dimethyl derivatives [(2,3-Me2C,H,)Ga(NR,)] have been obtained.29 The first gallacyclopentane [(CH,),Ga-p-AsBu',], has been synthesized.,' Various intramolecularly-stabilized gallium- and indium-organyls have been described namely (CH,),Ga(CH,),NMe, (CH,),GaCH,CHCH,CH,NNMe, and (C,F,)21n(CH,),NMe,;31 a large group of 5-methyl- 1 -galla(inda)-5-azacyclooctanes; and bis[ 3 -(dial ky1amino)propyll gal- lium tris [3- (dialk y1amino)propyll gallium and tris [3- (dialk y1amino)prop y1)indium derivative^.^ The dimer [Me,GaN(Si(H)Me,),] has been prepared from the reaction of Me,Ga with 1,1,3,3-tetramethyldisilazanein toluene the dimer crystal structure was determined.The compounds [Cy,GaNHPh], [Cy,GaNHBu'], and (tetramethyl-piperidine)GaCl feature short Ga-H-N distances of 2.1 13 A 2.33 A and 2.28(9) 8 re~pectively.~~ The compound mes,BN(Bu')GaEt is monomeric with trigonal planar coordinated gallium nitrogen and boron atoms.The B-N bond length is short (1.384(6)A) the Ga-N bond length is rather long (1.937(3) A) although the nitrogen is non-bridging.,' X-Ray structure determinations of the pyrrole derivatives Me,GaC,H,NMe and Me,InNC,Me show two formula units per cell forming 'n-dimers' via short intermolecular M-C contacts of 2.481 8 and 2.575 8 respective-iy.36 The monomeric low coordinate indium amides Bu~InN(2,6-Pr~C,H,)SiPh3 and In(N(SiMe,),} have been characterized by X-ray crystallography. Both have planar coordination at In and N with In-N bond lengths of 2.104(3)A and 2.049(1)8 respectively. These lengths are relatively short in comparison to the sum of atomic radii of indium and nitrogen. This shortening may be accounted for in terms of an ionic contribution to the In-N bond rather than by the presence of significant In-N p-p n-'' G.Muller and J. Lachmann Z. Naturforsch. Teil B 1993 48 1544. 29 G.E. Herberich U. Englert and D. Posselt J. Organomet. Chem. 1993 461 21. 30 A. H. Cowley S. Corbelin R.A. Jones R. J. Lagow and J. W. Nail J. Organornet. Chem. 1994,464 C1. '' H. Schumann 0.Just T. D. Seuss F. H. Gorlitz and R. Weimann J. Organomet. Chem. 1994 466 5. '' H. Schumann 0.Just T. D. Seuss and R. Weimann J. Organomet. Chem. 1994 472 15. 33 H. Schumann T. D. Seuss 0.Just R. Weirnann H. Hemling and F. H. Gorlitz J. Organomet. Chem. 1994 479 171. 34 D.A. Atwood V. 0.Atwood D. F. Carriker,A. H. Cowley F. P. Gabbai R. A. Jones M. R. Bond and C. J. Carrano J. Organomet. Chem.1993 463 29. 35 G. Linti J. Oryunomet. Chem. 1994,465 79. 36 J. Todtmann. W. Schwarz J. Weidlein and A. Haaland Z. Naturforsch. Teil B 1993 48 1437. Aluminium Gallium Indium and Thallium 45 bonding.37 The first example of a monomeric bis(amino)gallane with a gallium-silicon bond (tmp),GaSi(SiMe,) (tmp = 2,2,6,6-tetramethylpiperidino) has a crystal struc- ture containing a trigonal planar coordinated gallium atom with long Ga-N and Ga-Si bonds of 1.918 and 2.47A re~pectively.~~ New phosphinogallanes [Me,GaP(SiMe3),],39 and indanes [Me,InPPh,]340 have been described. In the former which is sterically crowded the Ga-P distance was determined to be 2.456(1)8, in the latter trimer where both In and P have distorted tetrahedral coordination the mean In-P bond distance is 2.62(1)A while the corresponding mean In-C distance is 2.17(1) A.[Ga{ p-PH(Bu'))Bu\)], bis(p-t-buty1phosphido)-bis(di-t-butylgallium),contains an almost planar Ga,P ring with average Ga-P bond lengths of 2.478,.,' In-As bonds have been found to occur in the dimer [R,InAs(SiMe,),] and the mixed bridge compound R,InAs(SiMe,),InR,C1,42 and R,InAs(SiMe,) (R = Me3CCH,).43 The reactivity of organogallium peroxides towards phosphines phosphites and triphenylarsine has been The syntheses and molecular structures of the dialkyl-aluminium and -gallium ~tannoxides,~' and of diphenyl-gallium and -indium ~tannanethiolates,~have been described. Some mixed transition-metal Group 13 compounds have been synthesized and examined. The compounds (q5-Cp)(CO),FeGa(Bu') (5) {(q'-Cp)(CO),Fe),GaBu' (6) and (q5-Cp)(CO),FeGa(But)2(q'-Cp)(CO),Fe), (7) have been synthesized.The average Fe-Ga distances in (5) and (6) are 2.413(4) and 2.411(5) 8,respectively and in (7)the Fe-Ga distance is slightly lengthened to 2.441(1) A. These distances and the IR carbonyl spectra suggest that any n-interaction between the iron and the gallium p-orbital is probably very weak.47 The In-Mo distances 4.0401(5) and 4.0703(5) A and the large In-S-Mo angles indicate no interaction between the two different metal centres in indium(II1) thiolate-bridged molybdenocene complexes [InCl {MoCp,(p-SEt),),][BPh,] .48 Novel stable and volatile organoindium transition metal com- plexes of the type [L(CO),)M],[InR,-,(D)] (M = Mo W Mn Re Fe Co Ni; L = q'-Cp CO; R = CH,SiMe, (CH,),NMe,; D = 0,N donor; n = 1-4; a = 1,2) have been prepared in high yields.49 The reaction of Ar*GaCI with Na[Mn(CO),] in Et,O solution produces a mixed crystal of the first reported digalloxane [Ga(Ar*){Mn(CO),)],O and [Ga(Ar*)(CI){Mn(CO),f] (Ar* = ~,~,~-Bu',C,H,).~' The compounds (C,Me,H),GaCI Ga(C,Me,H) and Ga(C,Me,) have been 37 M.A.Petrie K. Ruhlandtsenge H. Hope and P. P. Power Bull. Soc. Chim. Fr. 1993 130 851. 38 R. Frey G. Linti and K. Polborn Chem. Ber. 1994 127 101. 39 M. D. B. Dillingham J. A. Burns J. Byershill K. D. Gripper W. T. Pennington and G. H. Robinson Inorg. Chim. Acta 1994 216 267. 40 J.A. Burns M. D.B. Dillingham J. B. Hill K. D. Gripper W.T. Pennington and G. H. Robinson Organometallics 1994 13 1514.41 K. Kirschbaum and D. M. Giolando Acta Crystallogr. Sect. C 1994 50 1244. 42 L. J. Jones A. T. Mcphail and R. L. Wells Organometallics 1994 13 3634. 43 M. F. Self A. T. Mcphail L. J. Jones and R. L. Wells Polyhedron 1994 13 625. 44 M. B. Power J. W. Ziller and A. R. Barron Organometallics 1993 12 4908. 45 S.U. Ghazi R. Kumar M. J. Heeg and J. P. Oliver Inorg. Chem. 1994 33 411. " S. U. Ghazi M. J. Heeg and J. P. Oliver Inorg. Chem. 1994 33 4517. 47 X. M. He R.A. Bartlett and P. P. Power Organometallics 1994 13 548. 48 M.A. A. F. D. Carrondo A. R. Dias M. H. Garcia P. Matias M. F. M. Piedade and M. J. V. Debrito J. Organornet. Chem. 1994,466 159. 49 R. A. Fischer E. Herdtweck and T. Priermeier Inorg. Chem. 1994 33 934. 5o A.H.Cowley A. Decken C.A. Olazabal and N.C. Norman Inorg. Chem. 1994 53 3343. 46 J.P. Maher prepared. The latter exists as discrete molecules with all C5Me5 rings q’-bonded to Ga with an average C-Ga distance of 2.037 A metastable solution of GaCl has been shown to react with LiCp or MgCp compounds to form several new cyclopentadienyl- gallium(1) species GaCp* GaCpBu‘ GaCp((SiMe,),) and Ga(cp(B~),).’~ (vide supra A1 cyclopentadienide corn pound^.^^-^^} The new organogallium(1) compound [Ga(CH,CMe,)] has been prepared by the reduction of Ga(CH,CMe,),Cl using either sodium or lithium with naphthalene in thf. The [Ga(CH,CMe,)] probably exists as a mixture of species which are gallium cages containing from 6 to 12 gallium atoms.’ Weak arene-thallium interactions have been observed in the covalent thallium(1)-nitrogen compound [2,6-Pr\C6H,(Me,Si)NTl]4.54 Dimethyl(diphenylphosphinothioato)thallium(m) shows a polymeric structure that can be regarded as a folded ribbon formed by supramolecular association of four-membered TlSOP chelate rings connected through inter-unit dative 0 -+ T1 bonds (Tl-0 = 2.509(7)A) and T1-S secondary interactions (TI-S = 3.402(3)A).Overall the thallium atoms are six-coordinate in a severely distorted octahedral geometry.” The crystal structure of dimethyl(di-n-propy1dithiocarbamato)thal-lium(II1) [TlMe,(S,CNPr2)] has been determined. The thallium atom is coordinated to the two sulfur atoms of a slightly anisotropic bidentate dithiocarbamate ligand and to the two methyl groups which form a highly distorted tetrahedral environment.In the crystal lattice these units are linked by additional weak T1-S interaction^.^^ A new type of stable polymetallic chain compound involving Tl”’ and containing a B-T1-transition metal bond sequence [(rn-H2C,B,,H,)T1(Cl)M(CO),] which is analogous to the B-carboranyl-Hg” derivatives has been formed by the reaction of NaM(CO) (M = Mn Re) with TlCl in thf.57 2 Hydrides Apart from boron none of Group 13 form an extensive series of hydrides recent reviews have described the current state of research.58 Matrix isolation studies in solid argon have been applied to the preparation and study of aluminium gallium and indium di- and tri-hydrides vibrational frequencies and force constant data were disc~ssed.’~ The reaction of equimolar amounts of AlH,NMe and M(CH,SiMe,) (M = Zr Hf) in benzene lead to the exchange of all three Al-H bonds for Al-CH,SiMe bonds and the isolation of Al(CH,SiMe,),NMe,;60 Al(CH,Ph),NMe has been produced from Zr(CH,Ph),.The reaction of H,MNMe, M = A1 or Ga with Hfacac has been shown to cause metallation and reduction (for 51 H. Schumann S. Nickel and R. Weimann J. Organomet. Chem. 1994 468,43. 52 D. Loos and H. Schnockel J. Organomet. Chem. 1993 463 37. 53 0.T. Beachley J. C. Pazik and M. J. Noble Organometallics 1994 13 2885. 54 S. D. Waezsada T. Belgardt M. Noltemeyer and H. W. Roesky Angew. Chem. Int. Ed. Engl. 1994,33 1351. 55 J. S. Casas A. Castineiras 1. Haiduc A. Sanchez J. Sordo and E. M. Vazquezlopez Polyhedron 1994,13 1805.56 J. S. Casas M. V. Castano C. Freire A. Sanchez J. Sordo E. E. Castellano and J. Zukermanschpector Inorg. Chim. Acta 1994 216 15. 51 A.Y. Usyatinskii G.Z. Suleimanov E.A. Zulfugarly V.A. Antonovich V.I. Bregadze and I. P. Beletskaya Russ. Chem. Bull. 1993 42 554. 58 A. J. Downs and C. R. Pulham Chem.SOC.Rev. 1994,23,175; C. L. Raston J. Organomet. Chem. 1994,475 15. 59 P. Pullumbi C. Mijoule L. Manceron and Y. Bouteiller Chem. Phys. 1994 185 13; ibid. 1994 185 25. 60 W.G. Feighery R. U. Kirss C. H. Lake and M. R. Churchill Inorg. Chim. Acta 1994 218 47. Aluminium Gallium Indium and Thallium 47 aluminium) or only reduction (for gallium) of the b-diketone both products are binuclear species [Al {OC(CF )=CHCH (CF )0)(NMe ),I and (R ,R ,S/S,S,R)dia-stereoisomer and [Ga,{rac-OCH(CF,)CH,CH(CF,)O) ,(NMe,),] containing five- or four-coordinate metal centres respectively.61 Bis(diethy1amino)aluminium hydride and lithium tris(dihexy1amino)aluminium hydride have been shown to be much weaker reducing agents than lithium aluminium hydride for a wide variety of organic substrates showing some interesting specific reductions., 3 Metal-Metal Bonded Compounds A novel thallium compound Na,K,,Tl,, containing isolated T1:- and T1;- units has been prepared in high yield by fusion of the elements in sealed Ta containers followed by slow cooling and annealing at 250 “C.The crystal structure shows two T1 units and one Tl unit ordered in layers and well separated by the cations which bond to and bridge between faces edges and vertices of the clusters.The T1 is a distorted trigonal bipyramid the new Tl geometry with (TI-TI) = 3.13-3.44.& can be obtained by substantial elongation of two side edges of a tricapped trigonal prism so that the intervening face-capping atom moves close to that face and becomes eight-b~nded.~~ An alloy previously described in the phase diagram of barium and gallium as ‘BaGa’ has turned out to be containing isolated octahedral Ga clusters which are surrounded by a cuboctahedron of twelve Ba atoms. Application of Wade’s rules to the Ga naked cluster gives an excess of two electrons per formula There have been two reports of materials containing TI-T1 bonds. Tetrakis (hypersily1)dithallium has been described as a divalent thallium c~mpound,~’ and [MeSi(Bu‘NTl),] an amide of tris-(t-buty1amino)methylsilaneas a centrosymmetric dimer held together by TI-T1 bonds.66 In solid thallium(1)-bis(trimethylsilyl)amide cyclic dimers have been shown to be linked to infinite chains by intermolecular T1-TI contacts.67 The anion [R,AlAlR,Br]- (R = CH(SiMe,),) with an aluminium-aluminium and a terminal aluminium-bromine bond has been reported to be formed when A1-A1 bonded [R,AlAlR,] reacts with LiBr in n-pentane in the presence of tmeda.The crystal structure determination shows that the A1-A1 bond length is not significantly different (2.643A) from that in the starting material whereas the Al-Br bond is rather long (2.476A) indicating a weak coordinative bonding.68 The sterically highly shielded bases bis(trimethylsilyl)methyllithiumor bis(dimethylphosphany1)methyllithium react with [R,AlAlR,] to yield under deprotonation of a methyl group a carbanionic species which is stabilized by an interaction with one of the coordinatively unsaturated A1 atoms.With the former base a five-membered heterocycle Al,SiC, is formed the Al-A1 bond remaining uncleaved and the A1-A1 bond length only slightly changed in 61 J. L. Atwood F.C. Lee C. L. Raston and K. D. Robinson J. Chem. SOC.,Dalton Trans. 1994 13 2019. J. S. Cha 0.0.Kwon and J. M. Kim,.Bull. Korean Chem. SOC.,1994,15 132; J. S. Cha 0.0.Kwon and J.C. Lee ibid. 1993 14 743. 63 Z.C. Dong and J. D. Corbett J. Am. Chem. Soc. 1994 116 3429. 64 M.L. Fonasini and M. Pani J.Alloys Comps. 1994 205 179. 65 S. Henkel K. W. Klinkhammer and W. Schwarz Angew. Chem. Int. Ed. Engl. 1994 33 681. 66 M. Veith A. Spaniol J. Pohlmann F. Gross and V. Hunch Chem. Ber. 1993 126 2625. 67 K. W. Klinkhammer and S. Henkel J. Organomet. Chem. 1994 480 167. 68 W. Uhl U. Schutz S. Pohl and W. Saak Z. Naturjorsch. Teil B 1994 49 637. 48 J. P. Maher comparison to the neutral starting compound.69 It was previously observed that [R,AIAIR,] reacts with potassium in 1,2-dimethoxyethane to form the surprisingly stable radical monoanion [R,AIAIR,] * -[K(dme),] + ;however longer reaction times of some days at room temperature and with an excess of potassium give complete decomposition with cleavage of ether molecules and formation of several new products such as R,A1(Me)OC,H40MeK(dme) and R,A1(OC,H,0Me)2K.70 The digallane (tmp),GaGa(tmp),) is a pale yellow solid with a Ga-Ga bond length of 2.525(1)81 and its two-GaN unit twisted by 31" against each other.71 Several new (transition metal)-Group 13 metal cluster compounds have been prepared and characterized.The compound [(Cp*)ZrF,] reacts with AIMe to form a zirconium-aluminium-carbon cluster .72 The intermetallic derivatives [((2,6-Me2-NCH,),C,H,)M(Co(CO),),] (M = Ga In) have been prepared. The crystal struc- tures reveal that only one of the dimethylamine groups is coordinated to Ga so that the CGaCo moiety is pyramidal and the indium compounds has a distorted-trigonal- bipyramidal geometry containing a planar CInCo unit.73 The aqua cluster [Mo (p3-S)(p-0)(p-S),(H,0),14f reacts with indium metal in aqueous solution to give a novel sandwich cubane-type molybdenum-indium mixed-metal cluster [(H,0)9Mo,S,01nOS3Mo,(H20)9]8+ which is oxidized in hydrochloric acid back to the starting material via an intermediate tentatively assigned as [Mo31n(p3-S)(p-O)(p- S)2]:aii.74 Novel types of adducts of nickel carbonyl clusters with indium halides have been synthesized and subsequently characterized by X-ray diffraction.[NEt,] [Ni,(p3-InBr,)(y2-p6-In,Br,)(CO) JMe,CO has an octahedral Ni core capped on two adjacent faces by an In,Br moiety and on a third face opposite to one of the above by an InBr molecule. In [NEt,],[Ni,(y2-pu6-In,Br~),(CO) ,]-Me,CO two In2Br moieties are found to cap two opposite pairs of adjacent triangular faces of the Ni,octahedron.In both anions the remaining triangular faces of the octahedron are capped respectively by five and four face-bridging carbonyl groups whereas each nickel atom binds a terminal carbonyl ligand. The compound [NEt4],[Ni,,(p6- In)(y2-p6-In,Br,(OH)(CO)22)] has been shown to derive from two distinct Ni,(CO),(p2-CO) units sandwiching a unique bare indium atom and bridged by an In,Br4(p2-OH) moiety.75 Finally [(CO),CrTlCr(CO),] - the first complex reported as containing linear twofold-coordinated thallium(i) has been de~cribed.~ 4 Coordination Chemistry The coordination chemistry of aluminium has been reviewed in a recent book which has considered aspects of aqueous coordination chemistry low valent and paramag- netic compounds the chemistry of alkoxides thiolates and the heavier group 16 derivatives of aluminium (and gallium).77 h9 W.Uhl H. H. Karsch U. Schutz and A. Vester Chem. Ber. 1993 126 2637. 70 W. Uhl A. Vester D. Fenske and G. Baum J. Organomet. Chem. 1994 464 23. '' G. Linti R. Frey and M. Schmidt Z.Naturforsch. Teil 8,1994 49 958. " A. Herzog H. W. Roesky Z. Zak and M. Noltemeyer Angew. Chem. Int. Ed. Engl. 1994 33 967, -'C. A. Olazabal F. P. Gabbai A. H. Cowley C. J. Carrano L. M. Mokry and M. R. Bond Orgunometallics 1994 13 42 1. 74 F.G. Sakane Y.G. Yao and T. Shibahara. Inorg. Chim. Actu 1994 216 13. 75 D. E. Martin M.C. Iapalucci and G. Longoni lnorg. Chern. 1993 32 5536. 76 B. Schiemenz and G. Huttner Angew. Chem. lnt. Ed. Engl.1993 32 1772. 77 'Coordination Chemistry of Aluminium' cd. G. H. Robinson VCH New York 1993. Aluminium Gallium Indium and Thallium 49 Unusual coordination geometries have been observed for azaaluminatranes. The compound Al(Me,SiNCH,CH,),N has been shown to contain a trigonal mono- pyramidal aluminium centre and the dimeric azaaluminatrane [Al(Me,SiNCH,CH,),(HNCH2CH2)N]2 possesses an unusual cis-configuration of the central four-membered ring the aluminium atoms displaying a distorted trigonal bipyramidal coordination geometry.78 The related new monomeric azagallatranes Ga(RNCH,CH,),N (R = SiMe, SiMe,Bu') and dimeric azagallatrane [Ga(MeNCH ,CH ,),N] ,have been prepared. There have been further studies on the intriguing tri-radical species Ga(3,6-dbsq) and A1(3,6-dbsq) (dbsq = 3,6-di-t-butyl-l,2-~emiquinonate).EPR spectra recorded on these in a toluene glass at 77 K show signals at g values of 2,4 and 6 indicative of an S = 3/2 ground state. At lower temperatures magnetic measurements show evidence for an S = 3/2 ferromagnetically coupled ground state. The mixed-charge ligand complex (Ga(tmeda)(3,6-dbsq)(3,6-dbcat)shows no band that may be assigned as an interligand intervalence- transfer transition. 8o Di-radical compounds in the indium (111) halide-3,Sdi- t- but yl-o- benzosemiquinone system have also been characterized. Other interesting Group 13 complexes have been prepared. With [(en),M"'(OH),] ligands (M = Cr Co) heteronuclear complexes are formed with AlI'' Ga"' In"' and Tl"' in aqueous solution in all cases the [(en),M"'(OH),] groups act as hydroxo- bridged bidentate ligands.82 Indium(m) complexes of poly(pyrazoly1)borate ligands have been de~cribed,~ as have a series of thallium(1n) porphyrin complexes.84 5 Bioinorganic Chemistry Soil acidification has been shown to lead to increased ratios of absorption by plants of A13+ instead of Ca2+ and Mg2'+ausing in particular inhibitions in Mg2'- regulated biochemical processes which lead in turn to stunted tree With the above in mind the bioinorganic chemistry of A13+ has been reviewed,86 as has possible A13+neurotoxicity in acid rain.87 The determination of 26A1/27Al-ratios in biological materials with an accuracy of ca.2% is now possible by means of accelerator mass spectrometry (AMS).Thus 26A1can be used as a tracer to determine A1 content and distribution within complex chemical and biological systems and to investigate the kinetics and mechanisms of Al-transport pathways.88 Using AMS the aluminium distribution between the major cell compart- ments of human neuroblastoma cells grown in culture has been determined. Whilst 26A1 was retained by the nuclear proteins and nuclear sap 26A1 did not appear to bind " J. Pinkas T. K. Wang R. A. Jacobson and J.G. Verkade Inorg. Chem. 1994 33 4202. 79 J. Pinkas T. L. Wang R. A. Jacobson and J.G. Verkade Inorg. Chem. 1994 33 5244. " C.W. Lange B.J. Conklin and C.G. Pierpont Inorg. Chem. 1994 33 1276. 81 T. A. Annan M. A. Brown A. Elhadad B. R. McGarvey A. Ozarowski and D. G. Tuck Inorg.Chim. Acta. 1994 225 207. 82 F. Rominger A. Muller and U. Thewalt Chem. Ber. 1994 127 797. 83 D. L. Reger S. S. Mason A. L. Rheingold and R. L. Ostrander Inorg. Chem. 1994,33 1803; D. L. Reger S. S. Mason L. B. Regfer A. L. Rheingold and R. L. Ostrander ibid. 1994 33 181 1. x4 M.O. Senge K. Ruhlandtsenge K. J. Regli and K. M. Smith J. Chem. SOC.,Dalton Trans. 1993 3519; M.O. Senge ibid. 1993 3539. 85 W. Kaim and B. Schwederski 'Bioinorganic Chemistry Inorganic Elements in the Chemistry of Life' Wiley Chichester 1994. R6 Z. Kovarova Chem. Listy 1994 88 32. 87 R.B. Martin Acc. Chem. Res. 1994 27 204. " J. P. Day et al. Nuclear Instrum. Methods Phys. Res. Sect. B 1994 92 463. 50 J. P.Maher to the nucleic acids.89 With AMS it was found that for a young rat population 26Al-retention in the liver was seven times that in the brain.90 Also at the ANTARES AMS Centre the medical applications of 26A1 to measure aluminium concentrations in blood serum and in urine have been used so that aluminium resorption factors and rate constants for resorption elimination and exchange between the compartments have been obtained.” The biological availability of aluminium in mixed-ligand media of biological interest has been investigated by means of aluminium inhibition of hexokinase activity in ~itro.~~ Interactions and complexes between A13 + and various biochemicals have been studied including adenosine 5’-tripho~phate,~~ and the effects of aluminium ions on the dephosphorylation of phosvitin catalysed by acid pho~phatase.~~ Ternary complex formation has been studied in the A13+/AMP ADP ATP/oxalic acid lactic acid malic acid systems.Under physiological conditions at micromolar A13+ concentrations and at high ligand excess the aluminium is bound mainly to the nucleotides almost exclusively in the presence of oxalic and lactic acids and about 30% in the presence of malic acid.95 Radiolabelled 67Ga and ‘In-troponate complexes are now routinely used in medicine for tumour diagnosis and for radioimmunotherapy .8 There have been several structural- and solution-studies of complexes relating to this interest.96 The increased use of Group 3-5 semiconductors will increase the possibility of these materials entering the environment and so increased human animal and plant exposure with very uncertain consequences will occur thus it is important that their possible toxicological effects are examined.97 The same caveat is necessary for thallium should there ever be widespread use of thallium-based superconductor materials.98 Despite much chemical research there is scant data on the content and behaviour of thallium in soils and plank9’ 6 Miscellaneous This section highlights various other aspects of Group 13 chemistry not covered in previous sections.A novel microporous layered aluminophosphate (A1 :P = 0.75) in which there are two distinct kinds of eight-membered ring within the layers has been prepared 89 S.J. King et al. ibid. 1994 92 469. 90 D. Fink et al. ibid. 1994 92 473. 91 C. Hohl et al.ibid. 1994 92 478. 92 C. Exley N.C. Price and J.D. Birchall J. lnorg. Biochem. 1994,54 297. 93 I. Dellavia J. Blixt C. Dupressoir and C. Detellier Inorg. Chem. 1994 33 2823. 94 T. P. Geladopoulos and T. G. Sotiroudis J. Inorg Biochem. 1994,54 247. 95 T. Kiss I. Sovago R.B. Martin and J. Pursiainen J. lnorg. Biochem. 1994 55 53. 96 E. Cole R. C. B. Copley J.A. K. Howard D. Parker G. Ferguson J. F. Gallagher B. Kaitner A. Harrison and L. Royle J. Chem. SOC.,Dalton Trans. 1994,1619; F. Nepveu F. Jasanada and L. Walz Inorg. Chim. Acta 1994,215,237; I. Abrahams,N. Choi K. Henrick H. Joyce R. W. Matthews M. Mcpartlin F. Brady and S. L. Waters Polyhedron 1994,13,513; J. E. Bollinger J. T. Mague and D. M. Roundhill lnorg. Chem. 1994 33 1241. Y. Aoki M.M. Lipsky and B. A. Fowler Appl. Organomet. Chem. 1994,8,253;A. Tanaka A. Hisanaga M. Hirata M. Omura N. Inoue and N. Ishinishi Appl. Organomet. Chem. 1994 8 265. 98 R. J. G. Sobott Neues Jahrbuch Fur Mineralogie 1993 166 77. 99 V. Jovic ibid. 1993 166 43. Aluminium Gallium Indium and Thallium [A1,P40 6] [NH,(CH,),NH,][C,H oNH,] .loo The compound [CH,NH,] [Ga (PO,),OH] has a zeolite-like hydroxygalliophosphate framework containing Ga in both tetrahedral and fivefold coordination.' O' The first three-dimensional frame- work cobalt-gallium phosphate [C,H,NH][CoGa,P,O,,] has been described the three-dimensional structure is unique; large pores in the structure hold the pyridinium cations. lo2 The trimer Ga has been observed and characterized from its EPR spectrum in a frozen matrix.'03 Indium amides (III(NH)~), Li,In(NH,), Na,In(NH,)( +x) K,In(NH,)( +x) and indium nitride have been obtained as well as the new ternary nitride Li,InN,.'04 The coordination geometry about the indium in trichlorobis(tetrahydro-furan)indium(m) approximates to a trigonal bipyramid with three Cl atoms in equatorial positions and two axial tetrahydrofuran ligands.'05 The compound (PPh,),Pt,(p3-S),InC13 represents the first report of a square-based pyramidal structure of a five-coordinated adduct of InX3.lo6 The anions [In,SCl6I2 - [In,SBr612- [In,S,C16]3- [In,Se,C16]3- and [Ga,S,C16]3- are the first known chalcogenohalogeno anions of Main Group 13 elements.The first two anions consist of two InSX tetrahedra sharing a common sulfur atom.The frameworks of the remaining three anions each contain a six-membered ring of alternating metal and chalcogen atoms. Two terminal chlorine atoms complete a distorted tetrahedral coordination sphere around each metal atom.107 (PPh,),[In(S,)(S,)Cl] contains anions with trigonal-bipyramidal coordination of In with C1 occupying an axial position and the S and s6 groups being bonded in a chelate manner. In (PPh,),[In(S,)Cl,] the anion has a distorted trigonal-bipyramidal coordination of In atoms the S group occupying one axial and one equatorial position.'08 A new indium telluride [Bu:N],In,Te, has been synthesized by the cathodic dissolution of an In,Te alloy electrode at room temperature in a 1,2-diaminoethane solution of [Bu:N]I.The structure consists of one-dimensional (In,Te,) -chains isotypic to the chains found in the SiS and KFeS structure types.'09 Similarly the cathodic dissolution of Ga,Te gave [Ph,P][GaTe,(en),] the structure of which consists of one-dimensional [GaTe,(en),] chains held together by NH-Te hydrogen bonds.' The properties of thallium-based superconductors have been reviewed,' ' this comprehensive reference deals with just about every aspect of their chemistry including safety aspects of their use. The average valence of thallium in high-T loo R. H. Jones A. M. Chippindale S. Natarajan and J. M. Thomas J. Chem.SOC.,Chem. Commun. 1994,565. lo' F.P. Glasser R.A. Howie and Q.B. Kan Acta Crystallogr. Sect. C 1994 50,848. ln2 A.M. Chippindale and R.I. Walton J.Chem. SOC.,Chem. Commun. 1994 2453. J.A. Howard H. A. Joly and B. Mile J. Chem. Phys. 1994 100 3369. '04 A. P. Purdy Inorg. Chem. 1994 33 282. B. R. Whittlesey and I. P. Ittycheriah Acta Crystallogr. Sect. C 1994 50 693. M. S. Zhou Y. Xu C. F. Lam P. H. Leung L. L. Koh K. F. Mok and T. S. A. Hor Inorg. Chem. 1994,33 1572. lo' B. Krebs W. Bobb H. J. Wellmer and K. Wiesmann 2. Anorg. Allg. Chem. 1994 620 1234. lo' W. Bubenheim and U. Muller Z. Anorg. Allg. Chem. 1994 620 1607. C. J. Warren S. S. Dhingra R.C. Haushalter and A. B. Bocarsly J. Solid State Chem. 1994 112 340. C.J. Warren D. M. Ho R.C. Haushalter and A. B. Bocarsly J. Chem. SOC.,Chem. Commun. 1994,361. l1 'Thallium Based High Temperature Superconductors' ed. A. L. Hermann J. V. Yakhmi Marcel Dekker New York 1994.J. P. Maher T1-Ba-Ca-Cu-0 superconductors has been determined by capillary-tube isotacho- phoresis giving a value of 2.93-2.97.'12 MOCVD methods have been used to prepare phase-pure epitaxial T1,Ba,Ca2Cu,010 thin films (T,= 115OK) on single crystal LaAlO substrates using Ba(hfa),.tet Ca(Hfacac),.tet and Cu(Hfacac) (tet = tetraglyme); thallium was then incorporated into the films via Tl,O,.' l3 A new superconductor T1,~,Hg,~,Ba,Ca2Cu3O,,,, has been synthesized with a T,of 130OK. The possibility of substituting mercury for thallium in the 2223 cuprate was demonstrated.' l4 Another new mercury-thallium-based superconductor with a T of 132OK namely [Hg,~,Tl,.,Ba,(Ca -xSr,),CuO,O +J has been described." Thallium minerak are rare in nature and require due to their low temperature stabilities special physico-chemical conditions for their formation; mineral para- geneses for a wide range of sulfur-based minerals has been described.' l6 K.Watanabe K. Demura and K. Fueki Bull. Chem. SOC.Jpn. 1994 67 1024. B. J. Hinds D. L. Schulz D. A. Neumayer B. Han T.J. Marks Y. Y. Wang V. P. Dravid J. L. Schindler T. P. Hogan and C. R.Kannewurf Appl. Phys. Lett. 1994 65 231. 'l4 F. Goutenoire A. Maignan G.Vantendeloo C.Martin C. Michel M. Hervieu and B. Raveau Solid State Commun. 1994,90,47. N. H. Hur N. H. Kim K. W. Lee Y. K. Park and J. C. Park Muter Res. Bull. 1994 29 959. M. A. Elhaddad and G. H. Moh Neues Jahrbuch Fur Minerdogie 1993 166 9.