3 6,Al Ga In TI By A. J. WELCH Department of Chemistry University of Edinburgh Edinburgh EH9 3JJ 1 Boron The reactions of LaB6 and CeB6 with CO at 500 "C and at ca. 1000 "C have been studied,- and the temperature dependence of the rates of reactions discussed.' In La2Rh3B7 the B atoms form a zigzag chain structure,2 whereas in LuRh4B4 they occur pairwise at the unusually short B-B distance of 1.4(1)A.3The LuRh4B4 structure is the fourth variant discovered for the general class of ternary boride MM13B4 (M = rare earth M' = transition metal) an earlier type being exemplified by NdCo,B,. It is this last polytype to which the new borides EuOs,B and EuIr4B belong; their syntheses powder XRD patterns and magnetic susceptibilities have been reported. Magnetic properties have also been the subject of investigation in solid solutions of (Mn,-,Cr,),B (0 s x d 1) and (Mnl-yM~y)3B4 (0 s y s 0.8) synthesized at high temperatures and pressures.' New 'borides' of cobalt and nickel which catalyse hydrodesulphurization and promote liquefaction of coal are re- ported6 from reaction (400 "C 2000 psi H,) of the anhydrous metal bromide and two equivalents of NaB5Hs.The precise nature of these new species is unclear however since they have resistance to acids characteristic of borides and i.r. spectra that could be interpreted in terms of co-ordinated hydroborates. Ab initio calculations have been employed7 to study a number of water molecule- acceptor atom species (in C, symmetry) including H20B and H20A1. In the ground state of BOH the equilibrium B-0 distance is 2.617(2.704)A and the dissociation energy is 11.30(7.32)kJ mol-' values in parentheses being those obtained by improvement of the basis sets by counterpoise correction.In contrast published thermochemical data have been analysed to establish relationships between bond enthalpy and bond order for a number of simple boron containing molecules.8 The radical anion [B2But4IS a species with a B-B bond order of 1.5 has been synthesized by reductive (Na-K) coupling of But2BX (X = C1 or Br) and identified ' X. Xu M. Peng and J. Gao Huaxue Xuebao 1982,40,233. Yu. B. Kuzrna S. I. Mikhalenko B. Ya. Kotur and Ya. P. Yarmolyuk Dopou. Akad. Nauk Ukr RSR Set. B Geol. Khim. Biol. Nauki 1982 24. K. Yvon and D. C. Johnston Acta Crystallogr.Sect. B 1982 38 247. K. Hiebl P. Rogl and M. J. Sienko Znorg. Chern. 1982 21 1128. T. Ishii M. Shirnada and M. Koizurni Inorg. Chem. 1982,21 1670. A. Bonny R. Brewster and A. Welborn Znorg. Chim. Acta 1982 64 L3. 'J. Bentley J. Am. Chem. SOC.,1982,104,2754. J. B. Holbrook B. C. Smith C. E. Housecroft and K. Wade Polyhedron 1982,1 701. 19 A. J. Welch by e.s.r. ~pectroscopy.~ In a related experiment [B4Buf4IT is obtained from Na-K treatment of trans -B2C12But2. Although the structure of the neutral parent molecule is not known [B4Buf4I7 is assigned" the puckered cyclic geometry (l) as opposed to square or tetrahedral alternatives on the basis of minimized intramolecular crowding and a small boron coupling constant respectively.L (1) R = But Halides.-The adduct given by reaction between (PhO),PO and BC13 .was first reported more than 20 years ago and has recently found use as an inhibitor for the polymerization of (NPC12),. Alternative structures had been proposed but now a crystallographic study' * has verified the initial supposition oiz. co-ordination of the BCl moiety to the phosphoryl oxygen B-0 = lSll(5)A. With o-nitro- phenol BCl and GaCl give 1:1adducts whereas AlBr is spectroscopically shown to afford a 2 :1 (A1:nitrophenol) species.12 Adducts of mixed boron trihalides and tertiary amines have been studied' by multinuclear (especially I9F)n.m.r. spectros- copy from which it has been concluded that the cone angle of the amine rather than its basicity is the major influence on 19F chemical shift.With BF,13-, amines containing an aryl substituent yield cations [B(amine)2F2]+ countered by an anion or mixture of anions containing no boron. Partially hydrogenated boron halides halogenoboranes have significantly ex- panded the synthetic potential of the hydroboration reaction and have been reviewed together with their alkyl derivatives by Brown and K~1karni.l~ A rare non-thermolytic synthetic route to halogenoboranes is afforded by laser irradiation although it has recently been shown that such treatment of BC13-H2-(CH4 or SiF4) mixtures leads only to BHC12.15*'6 XRD and vibrational (i.r. and Raman) studies of K[CH,BF,] (2) have been undertaken in an attempt to assess the effect of CF us. CH3 substitution in boron chemistry." The B-C length 1.575(3) A is the shortest such distance yet measured in a borate and in particular is ca.0.06 A and 0.05 A shorter than those in Li[B(CH3)4] and K[CF,BF,] respectively. Concomitantly the mean B-F distance H. Klusik and A. Berndt J. Organomet. Chem. 1982,232 C21. lo H. Klusik and A. Berndt J. Organomet. Chem. 1982 234 C17. l1 M. L. Levin J. W. Fieldhouse and H. R. Allcock Acta Crystallogr. Sect. B 1982,38 2284. l2 B. A. Suvorov L. N. Orlova and R. V. Dzhagatspanyan Zh. Obshch. Khim. 1982,52,749. l3 A. Fox J. S. Hartman and R. E. Humphries J. Chem. SOC.,Dalton Trans. 1982 1275. l4 H. C. Brown and S. U. Kulkarni J. Organomet. Chem. 1982,239 23. S. V. Volkov A. F. Gurko and V. I. Lutoshkin Ukr.Khim. Zh. 1982,48,451.l6 A. V. Pankratov and G.V. Shmerling Khim. Vys. Energ. 1982,16 69. l7 D. J. Brauer H. Burger and G. Pawelke J. Organomet. Chem. 1982 238 267. B Al Ga,In TI 21 in (2) 1.424(5)A,is the longest yet found in a fluoroborate. Since the B atom in RBF3- is calculated (CNDO) to the positive and since the C in [CF3BF3]- will be less negative than that in [CH,BF3]- a reduction in the electrostatic component of the B-C bond could explain the crystallographic and force constant results. A review of the formation of fluoride-containing co-ordination compounds by the decomposition of transition-metal tetrafluoroborates has appeared. l8 Spectral study" of [CuL,(BF4),] {L = 2-(3,3-dimethyl-2-thiabutyl)pyridine} suggests a distorted octahedral structure in the solid state which is maintained in CH2ClZ solution.In methanol however dissociation of the co-ordinated BF4- ligands (and possibly one Ljoccurs. A crystallographic investigation2' of [Pt{(P(OMe)20)2BFz}z](3) has verified the non-ionic formulation and synthetic and 31P n.m.r. spectroscopic studies suggest that hydrolysis of (3) does not afford the macrocyclic complex (4),as had been Me Me H 00 MeO\I 1 0-P. P (3) (4) previously suggested. In (3) and in the related species [PtC1{(P(OMe)20)2BF2}- (PEt3)Iz1 the six atom PtPOBOP rings adopt distorted chair conformations and interestingly no lengthening of the ring P-0 bonds is observed in these species cf. analogues in which BF2 is replaced by H. BF2-bridged 14-and 16-membered macrocyclic ligands (N donor sets) of Ni and Co have however been synthesized22 and reactions of the nickel species with bases Diboron tetra-iodide B214 decomposes upon meltingz4 to yield B13 B919 and some Bs18.Halogenated B8 and B9 polyhedra will be discussed in the section on boranes. Boron-Oxygen and -Sulphur Compounds.-A new modification of silver(1 j ortho-borate Ag3B03 has been investigated ~rystallographically.~~ Although the silver partial structure and the positions of the B033- units are similar to those of the previous form the mutual orientation of adjacently stacked anions leads to an essentially linear 0-Ag-0 fragment 177.8(3)".The B-0 distance is 1.378(5jA and the B033- has imposed D3,,symmetry. Similar B033-symmetry is suggestedz6 J. Reedijk Comments Znorg.Chem. 1982 1 379. l9 E. W. Ainscough A. M. Brodie and N. G. Larsen J. Chem. SOC.,Dalton Trans. 1982,815. 20 D. E. Berry G.W. Bushnell and K. R. Dixon Inorg. Chem. 1982 21 957. '' S. G.N. Roundhill and D. M. Roundhill Acta Crystallogr. Sect. B 1982 38 2479. 22 J. Chakrabarty and B. Sahoo Indian J. Chern. Sect. A 1982,21 48. 23 J. Chakrabarty K. B. Naik and B. Sahoo Indian J. Chem. Sect. A 1982 21,370. 24 A. G. Massey and P. J. Portal Polyhedron 1982,1 319. '' M. Jansen and G. Bratchel Z. Anorg. Allg. Chem. 1982 489,42. 26 K. Machida G. Adachi and J. Shiokawa Chem. Lett. 1982 41. 22 A. J. Welch in the new haloborates Eu,BO3X (X = C1 or Br) obtained by solid state reaction between Eu,(B03) and EuX2 although the only symmetry required of six molecules per unit cell in space group P63, is C,.Both haloborates are ferromagnetic. Trigonal B03 and tetrahedral BO units occur in borosilicate glasses and such a glass has recently been used as a model to demonstrate that variable-angle sample- spinning ("B) n.m.r. spectroscopy at low magnetic field strength can afford optimum spectral res~lution.~~ 1.r. evidence supports the existence of BO tetrahedra in PbBPOs and P~BAsO,,~' which are structurally related to Stillwellite LnBSiO,. In Ni2NbB06 the BO tetrahedra share all four vertices with Ni06 or Nb06 octahedra and B-0 distances lie in the range 1.435(5) to 1.541(5)A.29 Much more uniform dimensions 1.446(7) to 1.488(7) A in one tetrahedron and 1.480(6) and 1.484(6) in the second are found in palladium metab~rafe.~' The sodium rich hydrated borate Na,[BO,(OH)] represents the first known example of a structure containing isolated partially hydrated triangular borate groups;31 in these the two B-0 bond lengths at 1.351(3) and 1.354(3) are ca.0.08shorter than B-OH 1.439(3)A. In anhydrous CU~~[(B~~~)~(B~~)~~~] B03 triangles occur as isolated groups and linked via 0,as B205 units in conjunction with isolated 0,-ions.32 Parameters within the ubiquitous tetraborate- anion [B405(OH)4]2- have been fairly accurately determined in a structural study of CaK2[B405(OH)4]2.8H20.33 A refinement of the crystal structure of proberite CaNa[B50,(OH)4].3H20 has also yielded parameters of high precision and since the H atoms were successfully located allowed the H-bonding system to be fully de~cribed.~, In proberite the pentaborate polyanion [B5Ol2I9- basic unit is poly- merized in chains by sharing of a tetrahedral corner with a triangular corner of the adjacent polyanion.Two tetrahedral corners however are shared in Na3[B5O9]-H20,a new phase of sodium borate synthesized at 523 K.35 Thermolyses of inderb~rite,~~ CaMg[B303(OH)5H,0],.4H20and of kalib~rite~~ HKMg2B12016(0H)lo-4H20 both yield magnesium tetra- and pyro-borates and respectively calcium tetra- and meta-borates and potassium pentaborate. Diborane reacts with HY zeolites initially to produce the function =Si-OB2H5 which transforms to +Si-O-BH above 500 K. At higher temperatures the zeolite framework is attacked affording the unit sSi-O-B=O via intermediate^.^' B=O double bonds are relatively rare but some multiple bond character is claimed39 for the one crystallographically unique B-0 bond 1.358(6) A in *' S.Schramm and E. Oldfield J. Chem. SOC.,Chem. Commun. 1982,980. 28 P. Tarte and U. De Wispelaere-Schroder C.R.Acad. Sci.,Series II,1982,295,351. 29 G. B. Ansell M. E. Leonowicz M. A. Modrick B.M. Wanklyn and F. R. Wondre Acta Crystallogr. Sect. B 1982,38,892. '(' W. Depmeier and H. Schmid Acta Crystallogr. Sect. B 1982,38,605. 31 S. Menchetti and C. Sabelli Acta Crystallogr. Sect. B 1982 38 1282. '* H. Behm Acta Crystuallogr. Sect. B 1982 38 2781. 33 X. Solans M. Font-Altaba J. Solans and M. V. Domenech Acta Crystallogr. Sect B 1982,38 2438. S. Menchetti C.Sabelli and R. Trosti-Ferroni Acta Crystallogr. Sect. B 1982 38 3072. J4 35 S. Menchetti C. Sabelli and R. Trosti-Ferroni Actu Crystullogr. Sect. B 1982 38 2987. 36 I. G. Saiko G. N. Kononova K. I. Petrov and V. N. Agafonov Zh. Neorg. Khim. 1982,27,2433. 37 I. G. Saiko G. N. Kononova K. I. Petrov and A. Ya. Tavrovskaya Zh. Neorg. Khim.,1982 27 335. 38 G. Geismar and U. Westphal Z. Anorg. Allg. Chem. 1982 487 207. 39 J. F. Sawyer and G. J. Schrobilgen Acta Crystallogr. Sect. B 1982 38 1561. B Al Ga In TI B(OTeF,), (5).The disproportionation of dimethoxyborane HB(OMe)* to diborane and B(OMe)3 has been re-in~estigated.~' Whilst confirmation of the disproportion- ation in the liquid phase was found no evidence was forthcoming for diborane formation in the gas phase only B(OMe) and Hz being detected by m.s.analysis. (Reproduced by permission from Actu Crystullogr. Sect. B 1982,38 1561) .r5) The same paper reports optimized conditions for the hydrogen reduction of B(OMe) to HB(OMe)* in a microwave discharge a method first demonstrated by the authors in 1981. B(OMe)3 reacts with methanol and piperidine in 1:1 1molar ratio to afford piperidinium tetramethoxyborate the anion of which is shown in (6).41The formation of this species supports the contention that the amine-catalysed (Reproduced by permission from Actu Crystullogr. Sect B 1982,38,676) (6) exchange of alkoxy-groups between trialkoxyboranes and alcohols proceeds uia tetra-alkoxyborates that have a discrete ionic existence even though in the present case the [B(OMe)J ion is strongly H-bonded through 0-1 to the piperidinium cation.Alkoxyboranes R,B(OMe)3-,,(n = 1,2 or 3) react (hexane -75 "C) with LiSiMe to yield silylborates [R B(SiMe3)4-n]- and not silylboranes R,B(SiMe3)3-n.42 40 P. M. Jeffers and S. H. Bauer Inorg. Chern. 1982 21 2516. 41 N. W. Alcock R. M. Hagger W. D. Harrison and M. G. B. Wallbridge Actu Crystullogr. Sect. B 1982,38,676. 42 W. Biffar and H. Noth Chem. Ber. 1982 115 934. 24 A. J. Welch Refluxing (benzene) boric acid with oxalic acid in the presence of either metal oxalate (M = K Na or NH,) or a metal carbonate (M = K Cs TI or NH,) or a base A (A = triethylamine or pyridine) yields bis(oxa1ato)borates (A or M)’[B(C,O,),]-; bis(ma1onato)borates are produced by analogous methods.The anions are characterized by i.r. and “B n.m.r. spectroscopies and vibrational spectra of the oxalate species are fully With two equivalents of 5 -aminosalicylic acid (H2L) in aqueous dmso B(OH) affords4 H[BL2].2H20 characterized by i.r. u.v. and n.m.r. spectroscopies and by thermal analyses. This contrasts with the reaction between B(OH)3 and H2L at 200°C described by the same group last year in which the salicylic acid was reported to act as a monofunctional group yielding B(OH)(HL)2.4H20. 8-Hydroxyquinoline (HL’) and a number of its 5-halogeno- and 5,7-dihalogeno-derivativesreact with BH3.thf to produce BH2L‘. These intramolecular adducts contain -0-BH2 tN functions and are efficient reducing agents for cycl~hexanone.~~ The completely novel neutral four co-ordinate boron-containing species B(O,CMe),(acac) (7) has been accidentally prepared (from reaction between Me’ I &‘\Me vanadium diboride and glacial acetic acid) and analysed by an accurate crystallo- graphic The boron atom is tetrahedrally bound to the two acetylacetonato-0 and two acetatu-0 atoms at average distances of 1.450(4) and 1.471(4) 8 respec-tively.In addition the keto-functions of the acetate ligands are symmetrically 0 disposed over tetrahedral faces with B -0 contacts of ca. 2.75 A. Although in localized terms this molecule could be viewed as an internal addition compound the C-0 and C-C distances in the acac ligand show the usual full delocalization. The first tris(trimethylsily1)methyl derivative of boron (Me,Si),CB(Ph)-[O(CH2)4C(SiMe3)3],(8) has been synthesized by reaction between (Me,Si),CLi and BF3 in Et20-thf followed by treatment with PhLi.,’ The initial product is identical to (8)but with F in place of Ph and is presumably formed via (Me3W3CLi cleavage of thf promoted by addition of the thf to either BF3 or (Me3Si),CBF2.The molecular structure of (8)has been determined revealing a distorted trigonally planar geometry at B to which the Ph groups lie perpendicularly. The B-C-1 distance is 1.567(11) A and the angle at B is widest between the two bulkiest groups i.e. C-1-B-C-11 128.6(8)”. 43 E. Bessler and J. Weidlein Z. Naturforsch. Teil B 1982 37 1020. 44 A. Terauda I. Ya. Lange and E. Svarcs Latv. PSR Zinat.Vestis Kim. Ser. 1982 267. N. Farfan and R. Contreras Nouo. J. Chim.. 1982,6,269. 46 F. A. Cotton and W. H. Ilsley Inorg. Chem. 1982 21,300. 47 C. Eaborn N. Retta J. D. Smith and P. B. Hitchcock J. Organomet. Chem. 1982,235,265. B Al Ga,In,TI (Reproduced by permission from J. Organomet. Chem. 1982,235 265) (8) Silyl- and germyl-thiuborane (9) are afforded by reaction of Me,Q-SLi (Q = Si or Ge) with a wide range of derivatives of halogenoboranes BRR'X (R,R' = Me Ph NMez etc; X = Br or Cl) products being characterized by 'H and "B n.m.r. spectroscopies and mass spectrometry. Silylthioboranes are reasonably stable and may be distilled in vucuo without decomposition whilst their germyl analogues disproportionate e.g. Me,GeSB(NEt,) +(Me3Ge),S + B(NEt,), upon attempted di~tillation.~~ Me3Q-Si-B /R R' (9) Boron-Nitrogen and -Phosphorus Compounds.-Boron imides RB=NBu' (R = Et Pr or Bu) that may be stored below -80 "C are produced (530"C)by elimination of ClSiMe from aminoboranes RB(C1)N(Bu')(SiMe3) and observation of v("BN) within the range 201 0-2020 cm-' implies considerable triple-bond character i.e.RB-G'NBu'. Important aspects of the chemistry of the imides include their trimerization to borazines alkyloboration to diborylamines cyclization (PhN,) to tetrazaborolines and formation of tetrazaborolines and azidoaminoboranes upon reaction with Me3SiN3.49 In consecutive publications Noth and co-worker~~" and Parry et al." describe the first well-authenticated examples of di-co-ordinated amidoboron cations.The synthetic routes are analogous uiz. AlBr with (tmp)B(NR2)Br (tmp = 2,2,6,6-tetramethylpiperidine) or with (tmp)B(R)Br (R = Me or Ph) yielding AlBr4- salts of [(tmp)=B=NR,]' or [(tmp)=B-R]' re~pectively,~" and AlCl 48 K. Hennemuth A. Meller and M. Wojnowska Z. Anorg. Allg. Chem. 1982,489,47. 49 P. Paetzold and C. Von Plotho Chem. Ber. 1982,115,2819. so H. Noth R. Staudigl and H.-U.Wagner Znorg. Chem. 1982 21 706. J. Higashi A. D. Eastman and R. W. Parry Znorg. Chem. 1982 21 716. 26 A. J. Welch with B(NR’,)Cl(R‘ = Pr’ or Me) yielding5* AlC1,- salts of [R’,N=B=NR’,]+. The tetramethyl species was found to be unstable in solution and possibly polymerizes or reacts with anion or solvent to increase the boron co-ordination number.A crystal structure determination of [(tmp)=B=NMe2]AIBr4 reveals a nearly linear N-B-N skeleton and planar and mutually orthogonal C,NB units thus confirming these amidoboron cations as heteroallenes. The shortness of both B -N distances 1.30(4)8 (to tmp) and 1.42(4)A to NMe ,imply multiple bond character consistent with i.r. stretching frequencies. Geometry-optimized STO-3G MO calculations on model systems were also performed the important conclusions of which were (i) for diamidoboron cations the DZdconformation (observed crystallographically) is preferred to the all-planar D,, one; (ii) diamidoboron cations are thermodynami- cally more stable than amido(organy1)boron cations because in the former the charge is better delocalized; and (iii) aminomethyleneboranes R2N-B=CH2 the missing link between amidoboron cations and allene would also have a D2d-type structure and might be amenable to synthesis by deprotonation of an amido(methy1)boron cation.Mainly STO-3G and some 4-3 lG calculations have also been used5* to explore the preference for bonding to boron through N or C in cyanide complexes of BX and AlX3 (X = H Me Cl or F). In all cases the preference is for the latter i.e. [NCBX3]- is the preferred species although the difference in energy between the two isomers decreases with increasing electronegativity of X (for X = F there is essentially no real preference). The molecular structure of diaminoborane HB(NH2) has been determined from the microwave spectra of eight of its The molecule is planar CZu, with N-B-N 122.0(3)0and B-N 1.418(1)A.Replacement of the B-bonded H by a further .rr-donating ligand would be expected to cause a lengthening of the B-N bonds because of the limited rr-acceptor capacity of the single (vacant) 2p orbital on boron. In the low-temperature crystal structures4 of B(NMe,) (10)the average B-N length is 1.439(1)& longer indeed than that in diaminoborane but an additional feature in (10) is that N-B rr-overlap is somewhat reduced by virtue of the fact that the (planar) BNC moieties are twisted in propeller-like fashion by ca. 30”relative to the central BN3 plane a result of intramolecular congestion. Comparing B 2p populations in HBF and HB(NH2), Thorne and Gwinn concludes3 that N is a better rr-donor to B than is F.Variable temperature I3C n.m.r. experiments on a series of dialkylaminofluorophenylboranesyield55 barriers to rotation about the B-N bond (and this a crude measurement of B-N bond strength) that are certainly not insignificant ca. 70 kJ mol-’. Indeed these barriers are of the same order as those in the chloro-analogues (whose syntheses and spectra were published ~eparately~~) but it is argued that in moving from (NR,)BPh(Cl) to (NR,)BPh(F) two factors are altered that might be expected to affect the N-B 52 D. S. Marynick L. Throckmorton and R. Bacquet J. Am. Chern. Soc. 1982,104,l. 53 L. R. Thorne and W. D. Gwinn J. Am. Chern. SOC.,1982,104,3822. 54 G.Schmid R. Boese and D. Blaser Z. Nuturforsch. TeilB 1982 37 1230.” R. H. Cragg T. J. Miller and D. 0”.Smith J. Organornet. Chem. 1982 231 C41. 56 R. H. Cragg and T. J. Miller J. Orgunornet. Chem. 1982,232 201. B,Al Ga In,TI (Reproduced by permission from 2.Naturforsch. TeilB 1982 37,1230) (10) rr-bond in opposite senses. First since F is a stronger rr-donor to B in acyclic three-co-ordinate boranes than is C1 N -+B rr-donation would weaken but secondly F is less sterically demanding than C1 and thus in the fluoro-derivative there would be more likelihood of co-planarity (and hence stronger N.-B rr-overlap) between the B and N co-ordination planes. Restricted rotation about the B-N bond is also reported5' for alkoxydialkylaminophenylboranes,for which four preparative methods are described and the same workers later extend their syn- thetic and spectroscopic studies to alkylamino- and dialkylamino-piperidinophenyl-boranes.58 A number of borane adducts of 3-and 4-substituted pyridines have been prepared and characterized and their "B n.m.r. spectra measured in an attempt to assess B-N bond strength (which is assumed to vary with "B chemical shift) as a function of the position of substitution on the pyridine ring.59 It is found that for CN C1 Br and F the B-N bond strength decreases with the substitution sequence 4,3,2 but that this trend is not appropriate to alkyl-substituted pyridineborane. In related publications60*61 Nutt and Wells examine the pathway of reactions between chlorobis(amino)boranes that contain an (organosily1)amino-group and LiBH4.A key step was found to be cleavage of a B-N bond in the aminoborane. 57 R. H. Cragg and T. J. Miller J. Organomet. Chem. 1982 235 135. '' R. H. Cragg and T. J. Miller J. Organomet. Chem. 1982 235 143. 59 S. Ferrence J. Iwamoto S. Levy N. Massey R. Williams and D. R. Martin Znorg. Chim. Acfa,1982 58 131. 6o W. R. Nutt and R. L. Wells Inorg. Chem. 1982 21 2469. 61 W. R. Nutt and R. L. Wells Inorg. Chem. 1982 21 2473. A. J. Welch The first example of the unsymmetrical cleavage of p -aminodiborane (6)occurs62 by reaction with a half molar equivalent of the bidentate base N,N,N',N'- tetramethyl-o -phenylenediamine (tmpd) according to equations (1)and (2). BH3 / [Me2NBH3]-+ (p-Me2N)B2HS% [Me2N 1-+ 0.5(Me2NBH2)2 (2) L BH3 It is presumed that the orrho substitution of the donor functions in tmpd favours formation of the chelated BH2+ moiety which is then protected by the bulky adjacent methyl groups whereas previous donor molecules have simply afforded (donor)-BH,-NR,-BH with j~ -aminodiboranes.In a later paper63 tmpd is shown to promote unsymmetrical cleavage in B4HI0 affording [(tmpd)BH2lfB3H8- and in thf.B,H, affording [(tmpd)BH2]+B3H8- thf and an uncharacterized (thf.BH) polymer. No similar cleavage of Me3N.B3H7 occurs however and possible reasons for this are discussed. Me (11) (12) The 1,3-dimethyl-2-(methylpyrazol-l'-yl)-l,3,2-diazaboracyclopentanes (11) and (12) have been prepared64 by condensation of 1,3-dimethyl-1,3,2-diazaboracy-clopentane with the appropriate pyrazole.In contrast transamination of 1,3-dimethyl-2-dimethylamino-l,3,2-diazaboracyclopentane(13) with pyrazoles is a poor route to such species. Compounds (11)and (12) form 1:1 molar adducts (14) with pyrazoles and in (14) the N-bonded H atom is shown to be delocalized. Me ()-NMe Me or Mez (14) Reaction of 3,s-dimethylpyrazole hydrochloride with LiBH4 affords 3,s-dimethylpyrazoleborane (IS) which on treatment with NaH and then pyrazole 62 P. C. Keller Inorg. Chem. 1982 21 444. 63 P. C. Keller Inorg. Chem. 1982 21,445. " F. Alam and K. Niedenzu J. Organornet. Chem. 1982 240 107. B Al Ga In,TI in dimethylacetamide yields for the first time the (pyrazoly1)borate anion (16)? Ni" (square planar) Zn" and Co" (both tetrahedral) complexes of (16) have been prepared.Chiral amine (A) adducts of cyano(pyrroly1-l)borane A + BH(NC4H4)CN have also recently been synthesized and their chemistries studied.66 If A contains an sp2 hybridized N atom the products are stable for a wide range of basicity of A whereas for sp3N only the stronger bases give stable products. The hydrolyses of hydro(pyrroly1- 1)borates [H B(NC4H4)4-,]- have also been investigated. 67 A low-temperature XRD study68 of adduct triphenylphosphineborane reveals the expected staggered conformation about the P-B bond 1.917 A and suggests only slight pyramidalization at B since the average H-B-H and P-B-H angles are 115" and 103" respectively. Whilst these values are almost certainly correct (unfortunately the spreads of the angles of which there are six of each type were not given nor were any errors quoted) this observation should not be taken as an indication of any inherent weakness in the P-B bond.In an attempt to assess the reactivity differences between Me3SiC1 and the isoelectronic Me2(BH3)PCl reactions of the latter with lithium salts of a variety of amides have been studied.69 Products (17) were obtained from the salts of acetamide 0 BHj 8 bMe2 R/ 'N' R' (17) R = H R' = Me R=Me R'=H R= Me R'= Me N-methyl acetamide and N-methyl formamide but not acetanilide or N-methyl benzamide. N.m.r. experiments imply that of two product isomers that shown in (17) is the major. Lower rotational barriers (C-N bond) are observed in these species than in their silyl analogues and this has been attributed to the polarity of the P-B bond PS+-B" uis-h-uis the Si-Me bond.Such polarity clearly has an 65 E. Frauendorfer and G. Agrifoglio Inorg. Chem. 1982,21,4122. 66 B. Gyori and J. Emri J. Organornet. Chem. 1982,238 159. 67 J. Emri and B. Gyori Polyhedron 1982 1 673. 68 J. C. Huffrnan W. A. Skupinski and K. G. Caulton Cryst. Struct. Commun 1982 11 1435. 69 C. H. Yoder and L. A. Miller J. Organornet. Chem. 1982,228 31. A. J. Welch H3B BH3 II important influence on the observation7' that reaction of 1,8-napthalenediyl-bis(dimethy1phosphane) (18) with thfOBH affords an equilibrium mixture (1:3) of the bisphosphanediborane (19) and cyclic boronate (20). Heterocyclic Derivatives.-As part of a study of cyclic T-conjugated molecules in general Inagaki and Hirabayashi71 have defined calculated and analysed the one electron delocalization energies of a number of 4- 5- and 6-membered boron- containing heterocycles concluding that the delocalizability increases in the order of the localizing < delocalizing < discontinuous conjugation and noting that the stability of these species increases with the number of adjacent donor-acceptor pairs or with the frequency of donor-acceptor alternation.Huckel MO calculation^^^ on B&6 indicate that the ?r-delocalization energy is smaller and the HOMO-LUMO gap larger than in the structurally similar porphine. It is speculated that the fact that B8SI6 is uncharged and that it has such high-lying acceptor orbitals renders it an unlikely potential ligand to transition-metal centres.B-0 n-bonding influences the magnetic screening of oxygen in a number of cyclic organo-boron-oxygen compounds studied by 170 n.m.r. Halogenomethaneboronates find use in a variety of synthetic transformations and a new facile route to them has now been The syntheses of optically active boronic acids and esters were first described two years ago but now these are available by an alternative route asymmetric hydr~boration.~~ Deprotonation of 1,l -diboronic esters yields carbanions that are stabilized by the adjacent boron atom,76 and if a further stabilizing function (e.g. SPh) is also available species of high utility are aff ~rded.~~ In the boronic esters (acety1acetonato)diphenyl boron (21) (two crystalline modifications) and (tropo1onato)diphenylboron (22) the chelate rings are respectively of B-envelope conformation and essentially planar with B-0 and B-C distances in the ranges 1.533(3)-1.555(11) A and 1.605(6)- 1.607(4) From the determination of stability constants evidence is pre~ented~~ that hexamethylborazine (hmb) and 10-methyl-10,9-borazarophenanthrene form T-complexes rather than N-donor complexes with 12.Towards GaCl, however hmb 7n T. Costa and H. Schmidbaur Chem. Ber. 1982 115 1374. 71 S. Inagaki and Y. Hirabayashi Inorg. Chem. 1982,21 1798. 72 B. M. Gimarc and N. Trinajistid Inorg. Chem. 1982 21 21. 73 B. Wrackmeyer and R. Koster Chem. Ber. 1982,115 2022. 74 P. G. M. Wuts and P. A. Thompson J.Organomet. Chem. 1982 234 137. 75 H. C. Brown P. K. Jadhav and M. C. Desai J. Am. Chem. SOC. 1982,104,4303. 76 D. S. Matteson and R. J. Moody Organometallics 1982 1 20. 77 D. S. Matteson and K. H. Arne Organornetallics 1982 1 280. 78 S. J. Rettig and J. Trotter Can. J. Chem. 1982 60 2957. 79 J. E. Frey G. M. Marchand and R. S Bolton Inorg. Chem. 1982,21 3239. B Al Ga,In TI Ph Ph Ph Ph ‘i 0’ ‘0 functions as a simple N-donor to yield an adduct (23) which is shownSo by crystallo- graphic study to possess a distorted B3N3 ring (unique N folded out of the plane by ca. 31” with ring bonds to it significantly the longest). In the solid state (23) is thus isostructural with its AlBr analogue reported last year. In toluene solution (23) is fluctional and interestingly the low temperature limiting spectrum is consistent with 1,3-di-N-donation to pentaco-ordinate gallium.s-s In attempting to investigate the exchange of substituents between 3,5-dibromo- 1,2,4,3,5-trithiadiborolane(24) and 1,2,3-trimethyl-1,3,2-diazaborolidine(25) (which proceeds via adduct formation) Noth and Staudigl serendipitously isolated the adduct (26) a result of using an aged and impure sample of (24).8’Rapid exchange of the bridge N(Me) and S functions occurs when the triazadiborolidine (27)or thiadiazadiborolidine (28)react with (24) or its dimethyl derivative and a possible mechanism for this exchange is discussed.82 The formation of (24) from the dimethyl analogue and the B-bromination of (28) follow endocyclic mechanism^.^^ Br n S‘ s Me Me Me Me Me/N\B/NIMe Br.$T? ‘N-N’ N-N I\ I\ I @-:sMe \/ Me Me/B,N/B\Me Me’B\s/B\Me (25) I ~e he Me (28) (26) (27) The anions of 1,2-azaborolines are isoelectronic with the Cp- anion and are therefore potential sources of 67~ -electrons to transition-metal centres.Numerous examples currently exist of complexes in which this analogy is exploited but all possess only one azaboroline ring per metal atom. Now however Schmid and 13‘’ K. Anton and H. Noth Chem. Ber. 1982,115 2668. H. Noth and R.Staudigl Chem. Ber. 1982,115 813. 82 H. Noth and R. Staudigl Chem. Ber. 1982,115 1555. 83 H. Noth and R. Staudigl Chem. Ber. 1982 115 3011. A. J. Welch co-workers have synthesized bis(1igand) complexes (29) (M = Fe or Co) in both transoid staggered (A) and eclipsed (B) conformations by the metal atom vapour te~hnique'~ and by reaction of the lithium salt of the diazaboroline anion with MBr2." A later paper" by the same group employs the former technique to synthesize the vanadium species and wet-chemistry methods for the But (replacing SiMe,) analogue of (29) and the bent-sandwich molecule [( 1-But-2-Me-1,2-NBC3H3)2TiBr2].In the azasilaboroline (30),incorporation of the (tetra-co-ordinate) Si atom within the heterocycle theoretically restricts the tr-donor capacity of the system to 4e- and in accordance Fe(CO) and CoCp derivatives of (30) and bis(1igand)-Fe and Me -Ni sandwich molecules have been synthesized by traditional and metal-atom vapour techniques respectively8' (R = Me).In a fascinating extension of this work Koster and Seidel" offer a bonding metal an alternative source of four conjugated 7r-electrons by using (30)with R = C(Me)=CH,. Reaction with Fe,(CO) affords both possible products (31) and (32) in 4 1 ratio whereas with 1,5,9-cyclo- "4 S. Amirkhalili U. Hohner and G. Schmid Angew Chem. Int. Ed. EngI. 1982 21 68. S. Amirkhalili R. Boese U. Hohner D. Kampmann G. Schmid and P. Rademacher Chem. Ber. 1982,115,732. 86 G. Schmid S. Amirkhalili U. Hohner D. Kampmann and R. Boese Chem. Ber. 1982 115 3830. 87 R. Koster G. Seidel S. Amirkhalili R. Boese and G. Schmid Chem. Ber. 1982 115. 738. R. Koster and G. Seidel. Angew. Chem. Int. Ed. Engl. 1982,21 207. B Al Ga In TI dodecatrienenickel (a source of Ni’) the dinickel complex (33) is formed.In (33) one Ni atom has access to 16e the other to 18e and they are held in mutual proximity {Ni-Ni 2.643(1) A} by their respective v-ligand systems. Crystallographic study of (34) demonstratesg9 the unique 77 5-co-ordination of the 1,3-diborolene ligand to the metal centre. Tetradecker” (35) and pentadecker” (36) complexes involving 7 5-1,3-diborofenyE ligands {the syntheses of the latter complexes starting from (34)) are also reported by the same group. (33) 0 co co Ni co co (35) The boron chelate (37) is afforded by treatment of tris(2-pyridy1)methanol with either four equivalents of HBF,.OEt or 40% aqueous HBF in propionic anhy- dride.92 Related diarylboron salicylideneaminato chelates have been the subject of recent controversy since following an initial claim93 that the transition state to 89 W.Siebert J. Edwin and H. Pritzkow Angew. Chem. Int. Ed. Engl. 1982 21 148. 90 W. Siebert J. Edwin H. Wadepohl and H. Pritzkow Angew. Chem. Int. Ed. Engl. 1982 21 149. 9‘ M.W. Whitley H. Pritzkow U. Zenneck and W. Siebert Angew. Chem. Int. Ed. Engl. 1982,21,453. 92 D. L. White and J. W. Faller Inorg. Chem. 1982,21 3119. 93 M. S. Korobov L. E. Nivorozhkin L. E. Konstantiovsky and V. I. Minkin J. Chem. Soc. Chem. Commun. 1982,169. A. J. Welch (37) enantiotopomerization (38) involved a species containing planar four-co-ordinate boron subsequent the~retical~~ and experimentalg5 evidence suggested instead that the likely mechanism simply involves ring opening to (39) rotation about B-0 and reclosure.The synthesis and characterization of a number of such chelates represented generally by (40),have been rep~rted,~~ some applications and a molecular structure determined for the specific compound with Z = 0 Y = H R = O-C6&(OH) and R' = Ph. Related chelates in which the fragments are part of the heterocyclic ring have also been reported.99 BPh(R') LN R YR (39) The 1,4-dibora-2,5-cyclohexadienecomplex (41)has been studied"' by semi- empirical MO calculations and by p.e.s. Reproduction of the experimental p.e. spectrum is generally good. Complex (41)is one of several species that may be afforded by nucleophilic substitution (at B) reactions on transition metal complexes of XB(CH=CH)2BX {X = OMe or (C,H4)FeCp}.Of these the ferrocenyl species are themselves particularly interesting in that their SynthTsis proceeds via initial generation of the 67r-electron [XB(CH=CH)2BX]2- dianion. lo' co Me-B-B-Me (41) 94 P. von Schleyer and E.-U. Wiirthwein J. Chem. SOC., Chem. Commun. 1 B2 542. " A. J. Boulton and C. S. Prado J. Chem. Soc. Chem. Commun. 1982 1008. 96 E. Hohaus 2.Anorg. Allg. Chem. 1982 484 41. " E. Hohaus Z. Anal. Chem. 1982 310,70. 98 R. Allmann E. Hohaus and S. Olejnik 2.Naturforsch. Teil B 1982 37 1450. 99 C. M. Lukehart and M. Raja Inorg. Chem. 1982 21 2100. "" M. C. Bohm M. Eckert-MaksiC R. Gleiter G. E. Herberich and B. Hessner Chem. Ber.1982 115 754. '01 G. E. Herberich and B. Hessner Chem. Ber. 1982,115 3115. B Al Ga In TI Boranes and Derivatives.-A comprehensive review by Barton describes both historical and modern systematic classifications of boranes and surveys the struc- tures of known boranes,"' whilst a review by Zakharova discusses the role of clusa-borate anions in the synthetic chemistries of Ni and Pd.lo3 Solid state i.r. and Raman spectra of MeNC-"BH3 its deuterated species CD3NCBH3 CH3NCBD3 and CD3NCBD3 and of MeNCBH3 have been recor- ded.Io4 The value of vNScincreases by ca. 150cm-' upon co-ordination and in agreement normal-co-ordinate analysis yields an NGC force constant ca. 10% larger than in free MeNC. Vibrational studies of BH4- and BD4- doped into alkali halides have shown that these ions retain tetrahedral symmetry in NaC1-type lattices but are distorted towards C3uin lattices with a CsCl ~tructure.'~~ Alkyl-substituted derivatives of the BH4- ion find use as versatile selective reducing agents that can additionally afford steric control of the reduction of cyclic and bicyclic ketones.Systematic synthetic routes to such borohydride derivatives have now been reviewed.lo6 New approaches to the bonding in polyhedral boranes and refinements and extensions of established ideas continue to be sought. Fuller and Kepert describe'" a simple method for calculating the energies of cluso-borane dianions in a variety of geometries that involves significant bonding interactions between all boron atoms.For the three examples quoted BgHg2- B9H92- and BI2Hlz2- the most stable geometries found are those that are well established by previous crystallo- graphic experiments viz. the dodecahedron tricapped trigonal prism and regular icosahedron respectively. An important result of this work is the finding of two alternative 12 vertex polyhedra (the C3h and D3h icosahedra) that could serve as possible transition states for icosahedral isomerization and which are energetically closer to the regular icosahedron than is the cuboctahedron of a diamond-square- diamond (dsd) isomerization. Calculation of the heats of formation of boron hydrides by the molecular orbital-bond index method must and does also involve cross-polyhedral B -B interactions. The method has been used"' to calculate AH," values for a number of nidu-and arachno -species and the only serious discrepancy between theory and experiment arises for B10H14.Calculated B-B bond energies per boron atom for these species as well as for some closu-dianions are also given. In recent years a new theory of the bonding in closo-clusters in general tensor surface harmonic (TSH) theory has been described and in 1982 the extension of TSH theory to nido-and arachno-boranes and -carbaboranes was reported. lo9 Inter alia the theory yields expressions for the HOMO'S of nido-and arachno-clusters that allow the well established analogy between the T systems of say [C2B9Hl1l2- and the Cp- anion. O'Neill and Wade'" have drawn attention to the lo* L. Barton Top. Curr.Chem. 1982 100 169. 1. A. Zakharova Coord. Chem. Rev. 1982,43 313. F. Watari Inorg. Chem. 1982 21 1442. M. I. Memon G. R. Wilkinson and W. F. Sherman J. Mof.Srrucr. 1982,80 113. Io6 H. C. Brown B. Singaram and S. Singaram J. Organornet. Chem. 1982 239,43. D. J. Fuller and D. L. Kepert Inorg. Chem. 1982 21 163. lo* D. Laurie and P. G. Perkins Znorg. Chim. Acta 1982 63 53. A. J. Stone and M. J. Alderton Znorg. Chem. 1982 21 2297. 'I" M. E. O'NeiII and K. Wade Inorg. Chem. 1982 21 461. A.J. Welch fact that closo-polyhedra with anomolous {in the terms of the polyhedral skeletal electron pair (PSEP) theory} electron numbers can occur when the parent borane dianion has non-degenerate frontier orbitals (e.g. dodecahedron B8HS2- LUMO a2 HOMO b,; tricapped trigonal prism B9H92- LUMO a2' HOMO a2'').In the same paper the value of a localized approach to the bonding in closo-polyhedra having n (n + l),and (n + 2) skeletal electron pairs (n = no. of vertices) is assessed and satisfactory bond networks are established for the species Cp4M4B4H4 (M = Co n skeletal electron pairs; M = Ni (n + 2) pairs). The bonding in these molecules has also been described in localized terms by King. ''I Reference to EHMO calcula- tions on these species was made in last year's Annual Report. Two-centre two-electron resonance-stabilized hybrid structures for a range of nido-and arachno- boranes have been established,112 and bond orders and atomic charges calculated by this approach compared with those given by MO calculations and by three-centre topological treatments.Finally a short note has appeared' l3 in which labeIling errors in a previous paper concerned with the localized descrip- tions of B6H10 and BsHs2- (D4d) are corrected and in which additions are made to published lists of valence structures for B8Hs2- (&d) and B12H122-. The value of the "B--"B two-dimensional n.m.r. technique as a structural tool in borane and heteroborane chemistry has been demonstrated' l4 by experiments on carbaboranes with (comparable) un- and H-bridged B-B bonds and on the metallaborane [6-(77-C5MeS)-6-CoB9Hl3 1. Full details have now been publi~hed"~ of a new systematic route to B2H6 B10H14 and most importantly the intermediate boranes and BSHll by hydride ion abstraction reactions that occur when BH4- B9H14-9 B3H8- and B4H9- respectively react with BX3 (X = halide).A typical reaction sequence is illustrated by equations (3) and (4) for the generation of B4H10. B3Hs-+ BX3 B3H7 + HBX3-(3) 0.5 B3H7 + 0.5 B3H7 0.5 B4H10 + (~/x)(BH~)~ (4) Previously the conversion of into B10H14 was of no practical use as the traditional route to the former involves degradation of the latter; however a one-pot synthesis of B1,,HI4 from B5H9 uia B9H14- is also described by the present authors. It has been reported'16 that mechanical activation of a mixture of MBH (M = Li Na or K) and iodine at 25°C affords B2H6. In an attempt to investigate the consequence on the bridge systems of Me for terminal H substitution in B2H6 Beaudet et al.have studied MeB,Hs by microwave spectroscopy. Unfortunately the abstract and the body of the paper are confusingly inconsistent. No asymmetry in the B-H-B bridges is actually found these links only becoming asymmetric (B-pH to the substituted B the shorter) if the substituted B is artificially displaced R. B. King Polyhedron 1982 1 133. W. C. Herndon M. L. Ellzey jun. and M. W. Lee Pure Appl. Chem. 1982 54 1143. 'I' W. N. Lipscomb and I. R. Epstein Inorg. Chem. 1982 21 846. T. L. Venable W. C. Hutton and R. N. Grimes J. Am. Chem. SOC., 1982 104,4716. M. A. Toft J. B. Leach F. L. Himpsl and S. G. Shore Inorg. Chem. 1982,21 1952. 'Ih V. V. Volkov K. G. Myakishev and I. I. Gorbacheva 120. Akad. Nauk SSSR Ser. Khim. 1982,2181. 'I7 C. W. Chiu A. B.Burg and R. A. Beaudet Inorg. Chem. 1982 21 1204. B Al Ga,In,TI towards the other boron. Some asymmetry is detected in the single bridge system of the B2H7- anion (42) structurally characterized'" as its [(Ph,P),N]' salt (with one molecule of CH2C12 of solvation). The overall conformation is staggered about (Reproduced by permission from J. Am. Chem. SOC.,1982,104,7669) the B -* * B vector 2.107(7)A; H1-B1 is 1.27(5) and HI-B2 is l.OO(5) A. This species represents the first example of an unsupported B-H-B bond and in keeping with the results of previous studies of unsupported M-H-M and M-H-B bonds the bridge in B2H7- is bent 136(4)",a finding that is particularly pertinent in view of the fact that the bridge in [Me,Al-H-AlMe,]- has been last year found and this year predi~ted,"~ to be linear.BCH6+ the fascinating missing link between B2H6 and the C2H6'+ di-cation has been predicted12' to be most stable in the (G-H)~ form of diborane and preliminary n.m.r. results1" on a system comprising the isopropyl cation and borane support this contention. Reaction of B3H8- with Hg2C12 in a non-co-ordinating solvent affords12' B3H7Cl- or B3H,C1,- depending upon molar ratios. B3Hs- reacts with Hg2Br2 to afford B,H,Br- (only) but not with Hg212. Some evidence has been found for the (transient) existence of B3H7F-. In B3H7Cl- the chloride is labile and readily substituted by CN- SCN- and BH3CN-. 1.r. and "B n.m.r. data for all the above derivatives of B3Hs- are reported. A structural of B3H7NCS- as its [(Ph,P),N]' salt confirms co-ordination through N and reports an asymmetric face-bridging bonding mode for one hydrogen atom.Unfortunately a recent redetermination of this structure at low temperat~re"~ has failed to locate the face-bridging H indicating instead a di-edge-bridged framework. The electrochemical oxidations of B3H8- and its C1 NCS and NCBH derivatives have been as a preliminary to possible anodic dissolution as a synthetic route to metallaboranes. [CU(H~BCNB,H~)(PP~,)~] successfully synthesized whereas B,H,Cl- and was "'S. G. Shore S. H. Lawrence M. I. Watkins and R. Bau J. Am. Chem. SOC.,1982 104 7669. J. M. Howell A. M. Sapse E. Singman and G. Snyder J. Am. Chem. SOC.,1982,104,4758. P. von R. Schleyer A. J. Kos J. A. Pople and A.T. Balaban J. Am. Chem. SOC., 1982 104 3771. ''I G. A. Olah L. Field and G. K.S. Prakash unpublished results quoted (ref. 7) in G. A. Olah and M. Simonetta J. Am. Chem. SOC.,1982,104 330. G. B. Jacobsen and J. H. Morris Inorg. Chim. Am 1982 59 207. S. J. Andrews A. J. Welch G. B. Jacobsen and J. H. Morris J. Chem. Soc. Chem. Commun. 1982 749. S. J. Andrews and A. J. Welch to be published. G.B. Jacobsen J. H. Morris and D. Reed J. Chem. Res (M), 1982 3601. 38 A. J. Welch B,H7NCS- suffer anodic dehalogenation. NaB,Hs.3L (L = dioxane) decomposes in Z~UCUOat 140°C to yield NaBH4 B5H9,H and L and a reaction scheme that involves the unstable species B2H4 has been proposed.'26 Optimized structures for B3Hs- and for the transient boranes B3H7 B3H9 B4H& and B4H12 have been ~redicted''~ by ab initio MO studies (6-31G basis set extended to 6-31G* with correlation at the MP3/6-31G level at minimum energy geometry).For B3H8- the preferred structure is the CZv form (43) but a single-p -H alternative with C symmetry (44) is only ca. 4 kJ mol-' less stable. B3H7 is predicted to be most stable as the (p-H)2 species (45) B3H9 as the D3h(p-H)3 structure (46) B4Hg as (47) and B4H1 as (48). Calculations at the extended Hiickel level have been 1.810 (43) (44) (45) H\ H H\ ,H H H H GBWH-B iH / 'D' 'H H' (47) employed to study triborane in its three known modes of bonding to transition-metal fragments and to assess its ligand 21s. cluster-component behaviour.lZ8 For B3H7 with B-B-B 120" (as in [(MezPPh)2PtB3H7])the analogy with the q3-allyl ligand is reinforced whilst for B3H8- with B-B-B angles of 60" (as in [(CO),cr B,Hs]-) the triborane still has ligand characteristics bonding in bidentate fashion.For B3H7 with B-B-B 90" {as in [(C0)6Fe2B3H7]} however three assessed criteria (mixing of ligand and metal orbitals density of empty low-lying orbitals and charge distribution) all point to substantial cluster character. Two groups have prepared different isomers of (Cl2B)BsHs. Reaction of KBsHs with BCl affords129 [p2,3-C12B-B5Hs] (49) whereas BCl reactsI3' with B5H9 to yield [1-C12B-B5Hs] (50). Both (49) and (50) were identified by n.m.r. ('H and 11 B) and i.r. spectroscopies and by mass spectrometry. Although treatment of ether adducts of (49) affords a new isomer its"B n.m.r.spectrum is not that of (50). 126 L. V. Titov E. R. Eremin and V. Ya. Rosolovskii Zh. Neorg. Khim. 1982 27 891. 127 M. L. McKee and W. N. Lipscomb Inorg. Chem. 1982 21,2846. 12' C.E. Houscroft and T. P. Fehlner Inorg. Chem. 1982 21,1739. 129 M.A. Nebson M. Kameda S. A. Snow and G. Kodama Inorg. Chem. 1982,21,2898. 13' D. F. Gaines J. A. Heppert D. E. Coons and M. W. Jorgenson Inorg. Chem. 1982 21,3662. B Al Ga In TI [2-C1BsHs] reacts with BCI in a similar manner to B5H9 affording the apically- substituted species [1-Cl,B-2-ClBsH7]. The B-B a-bonds of the 1-substituted molecules are cleaved by ether at elevated temperatures whilst at ambient temperature they readily insert ethene. 2-Aryl derivatives of pentaborane (9) (aryl = phenyl tolyl rn-xylyl) have been synthesized by the AlCl,-catalysed reaction of [2-ClBsH,] with the appropriate alkylbenzene.13' 'H and 13C{lH} n.m.r. studies of the tolyl and m-xylyl derivatives suggest that in both cases only the two least sterically hindered isomers are formed. Adducts of B5H9 with dppm {dppm = bis(diphenylphosphino)methane},dppe {dppe = 1,2-bi~(diphenylphosphino)ethane} and tmen (tmen = N,N,N',N'-tetramethylenediamine) and of B4Hs with tmen have been reported. Accurate structural studies of the B,Hg adducts and an approximate study of B4Hs.tmen show that whilst the P-donor ligands bridge apical and basal B atoms of a flattened pyramidal borane framework in which H atom rearrangement has occurred {see for example (511,the dppe adduct} the tmen adducts have suffered major structural (51) J.A. Heppert and D. F. Gaines. Znorg. Chem. 1982 21,4117 A. J. Welch change. As exemplified by (52) (the B5H9 adduct) the N-donor ligand chelates one originally basal B that is bound only to the originally apical B. The role of the different T bonding capabilities of the P-and N-donor ligands in effecting these changes is Whilst the B5H9 adducts of dppm and dppe are hypho-boranes the B5H9.tmen adduct is perhaps best described as a (tmenBH) adduct of B4Hs having an arachno-arrangement of four boron atoms. (52) The bis(trimethy1phosphine) adduct of diborane(4) has previously been shown to effect the unsymmetrical cleavage of B2H6 and B4H1o.It does not however cause similar cleavage of B5H1 1. Complete halogen exchange on polyhedral boron compounds has been repor- ted134 for the first time B8Cls and B9C19 affording the respective perbromo- derivatives with AlBr,. The same paper also describes cage reduction upon heating BloCllo and BllCllt with hydrogen. B9C18H and B9C17H2 respectively are formed being identified by mass spectral analysis. The first examAe of non-halogenated derivatives of B9H92- and B11Hl12- have been prepared and In B9Hs(NH,)- and B9Hs(NMe3)- the amine substitutes at the 1-position (5-connected with respect to the polyhedron) and both species are stereochemically rigid. [B9H7(COHBloHsSMe2)2]2-is the only product of the reaction between B9H92- and MezSBloH8C0 in acetonitrile and in it the two boranyl substituents are thought to be non-adjacent.With dmso in acetic anhydride B9H9'- yields'36 B9H8SMe2- and bH7(SMe2)2. Both are stereochemically non-rigid the former occurring as a 1:2 equilibrium mixture of the 4-isomer and 1-isomer at room temperature. Raising the temperature increases the proportion of the 1-isomer via an intramolecular rearrangement whose activation barrier is ca. 88 kJ mol-'. B9H7(SMe2)2 crystal- lize~~~~ as the 1,5-isomer (53) but in solution is in equilibrium with the other 13* N. W. Alcock H. M. Colquhoun G. Haran J. F. Sawyer and M. G. H. Wallbridge J. Chem. Soc. Dalton Trans. 1982 2243. 133 M. Kaderna and G. Kodarna Inorg. Chem. 1982,21 1267. '34 A. J. Markwell A. G. Massey and P. J. Portal Pofyhedron,1982 1 134.E. H. Wong and M. G. Gatter Inorg. Cfiirn.Acm. 1982 61. 95. E. H. Wong M. G. Gatter and R. M. Kabbani Inorg. Chem. 1982,21,4022. 13' D. D. Bray R. M. Kabbani and E. H. Wong Acta Crystalfogr. Sect. B 1982 38 957. B Al Ga In TI (531 (Reproduced by permission from Acta Crystallogr.,Sect. B 1982,38 957) non-vicinal possibilities 43- and 1,8- these two isomers becoming increasingly favoured as the temperature increases. B1 lH1 12-yields135 only a mono(dimethylsu1- phide) derivative BllHloSMe2-. Thermolysis of the uruchno-species MC[B9Hl4]- M = CS'~~ or R4N139 (R = Me or Et) is reported to yield mainly the cluso-products M2+[B12H12]2-. [1,10-(N2)2-BloH8] (54) has been studied by X-ray crystallography semi-empirical MO calculations and p.e.s.I4O Overall agreement between experimental and calculated (geometry optimized) connectivity lengths is good.The cage fragment is found to have an electronic structure very similar to that of the parent species BloHlo2- and thus the BN2 capping units are analogized to BH-. In the presence of Lewis acids (e.g. BF3 AlC13 and especially SnC14) lead tetra-acetate oxidizes BloCllo2- to the radical anion B10Cl107 characterized by i.r. e.s.r. and electronic ~pectroscopy.'~~ The new species is shown to be a more powerful oxidizing agent than B9X9; radicals (X = C1 Br or I) generating neutral clusters B9X9 from them. The synthesis of BIoH14 by pyrolysis of mixtures of B2H6 and HZ is reported best yields (ca. 43%) being obtained at 493 K in the presence of an iodine catalyst,14' and the mechanism of molecular tumbling of decaborane (in CD~C~DS) as a function of temperature has been studied by analysis of 'H and "B n.m.r.relaxation times. 143 13* L. I. Isaenko K. G. Myakishev and V. V. Volkov Zzv. Akad. Nauk SSSR Ser. Khim. 1982 19. 139 L. I. Isaenko K. G. Myakishev I. S. Posnaya and V. V. Volkov Zzv. Sib. Otd. Akad. Nauk SSSR Ser. Khim. Nauk 1982,73. 14" T. Whelan P. Brint T. R. Spalding W. S. McDonald and D. R. Lloyd J. Chem. SOC., Dalton Trans. 1982,2469. 14' E. H. Wong M. G. Gatter and R. M. Kabbani Inorg. Chim. Acta 1982 57 25. 142 K. Jaworski P. Stefaniak and A. Urbanska Przem. Chem. 1982 61 124. 143 T. C. Gibb and J. D. Kennedy J. Chem. SOC.,Faraday Trans. 2 1982,78 525.A. J Welch The nido-anion [9-(NEt,)-B,,Hl1]- has been prepared from BI0Hl4 and pre- liminary crystallographic data of the potassium salt furnished. 144 Metallaboranes and Derivatives.-Spectroscopic evidence has been for extensive ion-pairing when NaBH is complexed with poly(ethene oxide) but not in the analogous NaBF complex. Further small amounts of NaBH doped into the NaBF complex do not markedly reduce the conductivity of the latter from which it is concluded that cation transport through the complex is not limited to one-dimensional movement through.the (helical) poly(ethene oxide) chains since such movement would be blocked by ion pairs Na'BH,-. Na[BD3CN] is an important reagent for reactions that are to be followed spectroscopically and a convenient procedure for its preparation has been reported.146 LiBH is a selective and more reactive reducing agent than NaBH, and the preparation of the former (as a 1:1 solvate) from the commercially available latter by metathesis with lithium halides has been described.147 Solvent-free LiBH is best achieved if the solvent is diethyl ether. Alternatively LiBH4 can be conveniently 144 A. V. Aagfonov L. A. Butman K. A. Sofntsev A. A. Vinokurov N. A. Zhukova and N. T. Kusnetzov Zh. Neorg. Khim. 1982,27,63. 145 R. Dupon B.L. Papke M. A. Ratner D. H. Whitmore and D. F. Shriver J. Am. Chem. SOC.,1982 104,6247. 146 T.M.Liang and M. M. Kreevoy Inorg. Synth. 1982 21 167. 147 H.C.Brown Y. M. Choi and S. Narasimhan Inorg. Chem. 1982 21 3657.B,Al Ga,In,TI 43 prepared by the addition reaction between H3B-SMe2 and LiH in ether followed by thermolysis to remove Me2S and Et20. 'Super hydride' LiEt3BH is in turn stronger than LiBH, rapidly reducing most organic functional groups. Accordingly the intermediate species LiR2BH2 and LiRBH3 have been prepared and subjected to preliminary examination as specific reducing agents. 14* NaBH in combination with various metal halides is known to be an efficient reducing agent for a number of functional groups to which NaBH alone is inert but mechanistic details of these systems remained uncertain. Recent experimenta- tion however has now suggested that the Co2B formed in the NaBH4/CoC12 system co-ordinates to certain functional groups and catalyses their NaBH reduction.149 Cp,Zr{C(O)Me}Me reacts with H,B.thf to afford Cp,Zr(BH,)* uia initial decar- bonylation to Cp2ZrMe2. "B n.m.r. studies indicate stepwise formation of inter- mediate species containing co-ordinated (uia 2 Zr-H-B bridges) BH3Me- and BH2Me,- ligands and thus the reaction initially involves the formal insertion of BH into a Zr-Me bond.150 An equimolar amount of BH,- reacts with M(BH4),.2thf (M = La Pr or Nd) in benzene at room temperature to yield [M(BH,),-thf]- whilst with excess BH,- the dianions [M(BH4)5]2- are produced. 15' The mode of attachment of the borohy- dride ligands to the metal atoms in these species is not established although in the related neutral tris-complexes M'(BH,),(M' = La or Ce) p3-co-ordination is claimed on the basis of i.r.data.'52 The co-ordination states p3- p2- and p '-(respectively tridentate bidentate and monodentate) are well established for the BH,- group bound to transition metals. The last mode is the least numerous being accurately characterized for only the first time in 1981 in the complex [Cu(PPh,Me),(p l-BH,)]. From analysis of its B-H stretching frequencies the related species [CU(PP~~M~)~(H~B{O~CM~})] is considered also to have a single Cu-H-B bridge bond,'53 and p'-co-ordination has been unequivocally established lS4 for a second time in [Cu(triphos)BH4] (triphos = 1,1,l-tris{(diphenylphosphino)methyl}ethane) (55) Although the bridging H atom is expected to lie somewhat off the local three-fold axis of the P3Cu moiety if the Cu-H-B bond is a closed 3c-2e one the displacement of HI in (55) appears substantial (one P-Cu-H1 angle is 99" and two are ca.130"). in p 2-Co-ordination of BH4-is establi~hed'~~"~~ [Ru(H)(BH4)-{PhP(CH2CH2CH2PPh2)2}] (56) on the basis of its room temperature 'H n.m.r. spectrum but the molecule is uniquely fiuctional at high temperatures uia p2-to H. C. Brown Gov.Rep. Announce. Index (US.),1982 82 3196. 149 S. W. Heinzman and B. Ganem J. Am. Chem. Soc. 1982,104,6801. I5O J. A. Marsella and K. G. Caultron J. Am. Chem. SOC. 1982 104,2361. 151 L. V. Titov L. A. Gavrilova U. Mirsaidov T. G. Vershinnikova G. N. Boiko and V. Ya. Rosolovskii Zh. Neorg. Khim. 1982 27 1953. 15* U. Mirsaidov A. Kurbonbekov and M. Khikmatov Zh. Neorg. Khim. 1982 27 2436. Is' P.G. Egan and K. W. Morse Polyhedron 1982 1 299. 154 C. A. Ghilardi S. Midollini and A. Orlandini Znorg. Chem. 1982 21,4096. 155 T. J. Mazanec J. B. Letts and D. W. Meek J. Chem. Soc. Chem. Commun. 1982 356. "'J. B. Letts T. J. Mazanec and D. W. Meek J. Am. Chem. SOC.,1982 104 3898. 14' A. J. Welch (Reproduced by permission from Inorg. Chem. 1982,21,4096) pl-rearrangement with subsequent rotations about the Ru-(p'-H)-B linkage (Scheme l),a mechanism that completely scrambles the BH4- H atoms. In (56) the triphosphine ligand occupies three meridional sites of the metal co-ordination sphere. The central part of the complex [Fe(H)(BH,)(triphos)] (57) is thus related to that of (56) as its geometrical isomer. The p2-bonding of the BH4- ligand of (57) is confirmed by a crystallographic study'" and interestingly variable temperature 31P{1H}n.m.r.spectroscopy indicates that (57) too is fluctional the A2X pattern observed at -80 "Ccollapsing to only a broad singlet at 50 "C. Clearly an analogous fluctional process to that occurring in (56)could be used to rationalize this observation. A warning concerned with assignment of the co-ordinating mode of BH4- on the basis of i.r. spectra has been given158 with reference to [Co(terpyridyl)(BH4)]. X-ray and neutral diffraction studies clearly establish p 2-co-ordination but there are three bands rather than the expected two in the B-Htermina stretching region of the i.r. spectrum and three weak/medium-weak bands rather than one or two strong bands in the B-HHbridging region.In the solid state the two bridging hydrogen 15' C. A. Ghilardi P. Innocenti S. Midollini and A. Orlandini J. Orgunomet. Chem. 1982 231,C78. E. J. Corey N.J. Cooper W. M. Canning W. N. Lipscomb and T. F. Koetzle Inorg. Chem. 1982 21. 192. 3,Al Ga,In T1 H H H H HC HC Scheme 1 (Reproduced by permission from J. Am. Chem. SOC.,1982,104 3898) atoms are asymmetrically bound to the metal (the neutron study gives Co-H 1.740(12) 1.707(12) A; B-Hbridge 1.290(9) 1.287(10) A; B-Hterminal 1.214(10) 1.217(11)A). Even greater asymmetry however is found in the bridge bonds of Ga(BH,),H (58) uia analysis of its gas-phase e.d. pattern.'" Similar study of Ti(BH& (59) reveals that each BH,- ligand is p3-bound to the metal atom.160 Somewhat surprisingly the molecule is significantly pyramidal at the metal B .-* Ti . -B 115.8(7)". p3-co-ordinated BH4- also occurs in Zr(BH4) and Hf(BH& and the u.v.p.e. spectra of these species have been re-recorded and re-assigned,16' some assignments differing from those previously published. A parallel description of the bonding in Zr(BH4) is presented based upon the results M. T. Barlow C. J. Dain A. J. Downs G. S. Laurenson and D. W. H. Rankin J. Chem. SOC., Dalton Trans. 1982 597. 160 C. J. Dain A. J. Downs and D. W. H. Rankin Angew. Chem. Int. Ed. Engl. 1982 21 534. A. P. Hitchcock N. Hao N. H. Werstiuk M. J. McGIinchey and T. Ziegler Inorg. Chem. 1982 21 793. A.J. Welch (Reproduced by permission from Angew.Chern. Int. Ed. Engl. 1982 21,534) of semi-empirical MO calculations and these rationalize the preference for p 3-bonding. The paper concludes by predicting that d6 MLs(BH4) species should have p '-bonded BH4- and that in d6 ML4(BH4) the BH4- should be bidentate. To date these predictions are borne out by experiment. An unusual overall reaction occurs'62 when [Ti(salen)Cl,] {salen = N,N'-ethenebis(salicy1ideneiminate)) is treated with LiBH4 in thf since the BH4- ion adds to the imino-group of the salen group rather than reducing the metal (as had been expected). It is argued that the initial reaction is substitutionof C1-by p 2-BH4-. The final product (60) was characterized crystallographically and contains two electron-deficient B-H-Ti-N rings with Ti-H 1.85(10) and 1.84(10) A.An important new text 'Metal Interactions with Boron Clusters' has been published. 163 In it appear authoritative chapters on bonding features transition- metal derivatives of nido -boranes metal derivatives of B3H8- main group metal- laboranes and carbametallaboranes a-bonded derivatives the electrochemistry of metallaboranes and boron clusters with transition-metal -H-bonds. '" G. Dell'Amico F. Marchetti and C. Floriani J. Chem. SOC.,Dalton Trans. 1982 2197. lb3 'Metal Interactions with Boron Clusters' ed. R. N. Grimes Plenum Press New York 1982. ISBN 0-306-40933-X. B Al Ga In T1 The role of small metallaboranes and carbametallaboranes in organometallic syntheses notably oxidative ligand fusion processes and the catalytic hydrogenation of alkenes and alkynes has been re~iewed.'~~ The major (of two) product of the reaction between B2H6Fe2(C0)6 and Fe,(CO) is [HFe4(BH,)(CO)12] (61).This is isoelectronic with the previously characterized [HFe4(CH)(C0)12] and may be classified as an arachno -cluster if the boron atom is considered interstitial. The Fe-H-B interactions in (61) are closed 3c-2e systems and being substantially more symmetric than the Fe-H-C moiety in the CH analogue may represent models that lie further along the reaction co-ordinate for C-H bond cleavage on a metal 0 164 R.N. Grimes Pure Appl. Chem. 1982 54 43. 16' K. S. Wong W. R. Scheidt and T. P. Fehlner J. Am. Chcm. Soc. 1982 104 1111. 48 A. J. Welch In analysing a number of mono-iron derivatives of B6H6,- by self -consistent charge EHMO calculations Spalding and co-workers find again that Fe(CO) units use tangential (3dx,-4px) and (3d,,-4pY) hybrid orbitals in cluster bonding but that there is little evidence for involvement of a (3dz2-4pz- 4s) (radial) orbital.'66 Such findings significantly qualify the often stated isolobal analogy between BH and transition-metal fragments such as Fe(CO) or CoCp.However Fenske-Hall calcu- lations on B5H9 [l-Fe(CO),-B,H,] [2-Fe(CO),-B4H,] and [1,2-{Fe(C0)3}2-B3H7] have been that reassert the validity of the analogy. Preparative routes to a-bonded BSHs complexes of transition metals have been described.16' CpFe(CO),I reacts with BSHs- to afford [2-{CpFe(C0)2}-B5Hs] whilst Co,(CO) reacts with BsH to yield 1-and [2-Co(CO),-B5H,] the latter also being formed by nucleophilic displacement of X from [2-X-BsH,] (X = C1 or Br) during reaction with NaCo(CO),.In contrast U.V. irradiation of CpFe(CO),I with BloHlo2- results169 in oxidative insertion of the CpFe moiety into the cage to afford closo-[CpFeBloHlo]2-. In attempting to assess the consequences of using C5Me,- rather than C5H5- in the system B5Hs-/CoC1,/C5H5- Grimes and co-workers not only produ~ed'~' [2-C5Me,-2-CoB4H,] [1,2-(C5Me5)2-1,2-Co2B4H6], and [1,2,3-(C5Me5),-1,2,3-Co3B4H4] (all of which are analogous to previously synthesized Cp complexes and the last of which (an extremely crowded molecule) was studied crystallographi- tally"') but also dicobalt-B and -B6 derivatives that have no Cp analogues.Under the conditions employed (B9H9 in the presence of NaH in thf) B9HI4- is also generated (see reference 115). Reaction of this with CoCl and CSMe5- affords four products [6-CSMe5-6-CoB9H13] [6,9-(C5Me5)2-6,9-Co2B8H12], [5,7-(C,Me,)2-5,7-Co,B8H12] and [6-C1-5,7-(C,Mes)2-5,7-Co2B8H1 '3 all of which have been to possess decaborane( 14)-like structure with a metal atom substi- tuted in the open face. The first examples of complexes in which metallaborane and carbametallaborane polyhedra are fused about a common metal vertex have been from reaction of B5Hs- or B9H14- with CoC1 in thf followed by addition of R2C2B4H5- (R = Me or Et). Since Co2' reacts much more rapidly with the carbaborane anion than with the borane anion it is necessary that the carbaborane be added last.A number of new species were reported and structurally studied bv n.m.r. spectroscopy and in three cases X-ray diffra~ti0n.l~~ It has already been established that under the reaction conditions employed B9H14- is generated from B5Hs- and the COB fragments obtained have B ,,HI4-like architectures. However 'the COB products obtained from B,H,- have the metal in the 5-position' {see for example (62)} 'while in those generated from B9H14- the metal occupies the 6-position' {see for example (63)). A possible mechanistic implication of this 166 W. K. Pellin T. R. Spalding and P. Brint J. Chem. Res. (M),1982 1335. 167 R. L. DeKock and T. P. Fehlner Polyhedron 1982,1 521. 168 M. B. Fischer D. F. Gaines and J.A. Ulman J. Organomet. Chem. 1982 231 55. Y. Lu X. Huang C. Sun and H. Ding Huaxue Xuebao 1982,40 191. T. L. Venable and R. N. Grimes Inorg. Chem. 1982 21 887. T. L. Venable E. Sinn and R. N. Grimes Inorg. Chem. 1982 21,904. T. L. Venable E. Sinn and R. N. Grimes Inorg. Chem. 1982 21 895. 173 L. Borodinski and R. N. Grimes Znorg. Chem. 1982,21 1921. 174 L. Borodinski E. Sinn and R. N. Grimes Inorg. Chem. 1982 21 1928. 49 B Al Ga In T1 OO.. BH BOtCH3 C H (62) The structure of [~-~~~-S-E~~C~B~H~-S-COB~HIJ Et (63) The structure of [2-thf-6-Et&B7H7-6-C0B9H121 (Structures (62) and (63) reproduced by permission from Inorg. Chern. 1982,21 1921) observation is that whilst the latter species could derive from stereospecific attack by the metal on B9H14-,formation of the former compounds may involve attack of B5H,- on a preformed CoBS or CoB4 cage.One of numerous degradation products of the reaction of B1,Hlo2-with trans-[Ir(CO)Cl(PPh3)2] in methanolic solution is the bis(urtho-cycloboronated) species (64) i~olated’~’ in very small yield (S1%).Essentially quantitative formation of the ortho -cycloboronated product (65)is a~hieved”~ by room temperature reaction of nidu-B9H12-with IrCl(PPh3)3 and (65)is transformed into the isomeric (66) by slight thermolysis (65°C). Both (65) and (66) are formally Ir”’ complexes with B 1oH14 architectures. At 85 “C (66) dehydrogenates to the iso-closo-[H(PPh,)-(Ph2PC6H4)(IrB9H8)],(67) characterized by X-ray crystallography and described as an Ir” species.With the methyl analogue of Vaska’s complex B9H12-J. E.Crook N. N. Greenwood J. D. Kennedy and W. S. McDonald J. Chem. SOC.,Chem. Commun. 1982,383. J. Bould N. N. Greenwood J. D. Kennedy and W. S. McDonald J. Chem. SOC.,Chem. Commun. 1982,465. A. J. Welch affords several new complexes including the degradation product [l,l,l-(CO)-(PMe,)2-1-IrB4H9],177a structural analogue of B5Hll and the arachno -IrB8 species [4,4,4,4-(C0)(H)(PMe,),-4-IrB8H8] (68) and related 1-chloro (and stereoiso- meric) analogue (69).17' Dehydrogenation and partial cage-closure of (68) and (69) occur quantitatively at 50-100 "C affording nido-[(CO)(PMe3)2(IrB,H,,,C1)] (70) and nido -[(CO)(PMe3)2(IrB8Hll)],(7l),respectively. More severe thermoly- sis (135 "C)results in decarbonylation dehydrogenation and further cage-closure to yield iso-closo -species.The product from (71) is isolated in only trace quantities but that from (70)was formed in sufficient amounts to allow structural identification via n.m.r. and crystallographic study. It is shown in (72). The metal atom again described as Ir" is bound to boron atoms 2,4,5 and 7 by links of 2.17-2.20& and to B-3 and B-6 by connectivities of 2.30-2.32A in a novel deltahedral arrangement. 177 J. Bould N. N. Greenwood and J. D. Kennedy J. Chem. SOC.,Dalton Trans. 1982,481. J. Bould J. E. Crook N. N. Greenwood J. D. Kennedy and W. S. McDonald J. Chem. Soc. Chem. Commun. 1982 346; ihid.,772. 17' B Al Ga In TI 51 CI (72) Typical -I and Rh' complexes oxidatively insert into arachno-3H14-to yield 6-metalla(111) derivatives of B10H14 characterized by multiple-resonance n.m.r.spectroscopy and in one case a crystallographic study. 179 With PtC12(PMe2Ph), arachno-[4-Me2S-7-MeO-B9H14] affords,'" inter alia the quite unprecedented species (73) in which a linear P-Pt-Pt-P spine links B6H9 and B3H7 sub-units. N.m.r. study of (73) indicates that the H atoms of the smaller fragment are arranged as in (74). When ~rachno-[(PMe~Ph)~PtB,H,~] is refluxed (toluene) a low yield of the conjuncto -platinaborane (75) is afforded,'" whilst not only conjuncto -species ((76)-(78)} but the unique confacial-conjuncto-product (79) are isolated by reac- tion of PtC12(PMe2Ph)2 with an equimolar mixture of syn-and anti-(previously i-and n-) B18H22.182 Compounds (76)-(78) are all isomers of [(PMe2Ph)2PtB18H20] whilst (79) is [{(PMe2Ph)2Pt}2B 18H 161.In reaction with Rieke metal slurries of Zn Ni and Co BloH14 reacts most unusually as an oxidizing agent since the products [M(BloH12)2]2- contain transi- tion-metal atoms in the +2 A range of oxidation states from Coo to Co'" 179 S. K. Boocock J. Bould N. N. Greenwood J. D. Kennedy and W. S. McDonald J. Chem. SOC. Dalton Trans. 1982 713. '13" R. Ahmad J. E. Crook N. N. Greenwood J. D. Kennedy and W. S. McDonald J. Chem. SOC. Chem. Commun. 1982 1019. M. A. Beckett J. E. Crook N. N. Greenwood J. D. Kennedy and W. S. McDonald J. Chem. SOC. Chem. Commun. 1982,552. Y. M. Check N. N. Greenwood J.D. Kennedy and W. S. McDonald J. Chem. Soc. Chem. Commun. 1982 80. lS3 D. F. Gaines and G. A. Steehler J. Chem. SOC., Chem. Commun. 1982 122. A.J. Welch P-Pt-Ppt -P u (74) are accessible (dependent upon the formal charge of the borane ligand) via electrochemical redox reactions of a number of cobaltaboranes (and one carba- cobaltaborane) in which either P or As atoms are also present in the cluster. The Co'" complex [CO(B~~H~~AS)~]~-, can be oxidized further but it is likely that this step involves a ligand-based 0rbita1.l~~ n (76) (77) W. E. Geiger D. E. Brennan and J. L. Little Inorg. Chem. 1982 21 2529. B Al Ga,In,TI n t Carbaboranes and Carbametal1aboranes.-Using both MO and bond energy calcu- lations on components of the series of equations (5) to (7) the driving forces for the incorporation of unsaturated hydrocarbons into borane clusters are identified as progressive B-C bonding and increased charge flow to and hence form’ed reduction of the C2 unit.ls5 It is argued that these processes are essentially similar to those that occur when such hydrocarbons interact with transition-metal surfaces.With small carbaboranes alkynes can be induced to insert into one or more terminal B-H bonds in the presence of catalytic amounts of the alkyne-bridged dicobalt species [(p-RC2R’)Co2(C0)6] (R = R’ = H Me or Et) this method representing the first general synthetic route to alkenylcarbaboranes.lS6 The exact mechanism of the reaction remains in some doubt.A number of small carbametallaboranes have been studied electrochemically,’87 from which it has been concluded that low metal oxidation-states are less stable in such molecules than in their C2B9analogues. In contrast to a previous suggestion it has now been shown’88 that in (80),one of the major products from the system [2,3-Mez-2,3-C2B4H5]z/NaH/Cp-/CoC12, the carbacobaltaborane and car-baborane frameworks are linked by a single three-centre B-B-B bond. The B4‘-B5’ B4’-B6 and B5‘-B6 distances are 1.737 1.842,and 1.978A (all *0.004 A) respectively. R. L. DeKock T. P. Fehlner C. E. Housecroft T. V. Lubben and K. Wade Znorg. Chem. 1982 21 25. ‘86 R. Wilczynski and L.G. Sneddon Znorg. Chem. 1982,21 506. ‘13’ W. E. Geiger and D. E. Brennan Inorg.Chem. 1982 21 1963. A. J. Borelli jun. J. S. Plotkin and L. G. Sneddon Znorg. Chem. 1982 21 1328. A. J. Welch 'C (Reproduced by permission from Inorg. Chem. 1982 21,1328) A number of peralkylated nido-2,3,4,5-C4B2 species (alkyl = Me Et or Pr') have been studied by multinuclear n.m.r. experiments and various isomers identified.'89 Full details of the formation of the closo-cations [3-Me3L-2,4- C2BsH6]' and [5-Me3L-2,4-C2BSH6lf (L = N or P) by treatment of the appropriate neutral chloro-derivative of C2B5H7 with base followed by C1- abstraction with BC13 have now been given.'" An alternative route to the 3-Me3N cation is from 1-C1-2,4-C2B5H6 followed by rearrangement more probably via the dsd type than by triangular face rotation (tfr).Dsd is also preferred on the basis of observed rate patterns in a study"* of rearrangements in the [B-Me-2,4-C2BsH6] system and plausible dsd pathways for the 1-Me $ 3-Me $ 5-Me isomer interconversion are given in Scheme 2. Direct insertion of a [Pt(PEt3)J fragment into the closo-carbaborane [2,4-Me2- 2,4-C2B5H5] affords the very open quasi-dodecahedra1 species (81) and the more regular (although still somewhat misshapen) tricapped trigonal prismatic carbadi- platinaborane (82). 192 This latter compound (plus regenerated carbaborane) is always given as a by-product during attempted recrystallizations of (8l) suggesting that the initial insertion is reversible. Related experiments in which the carbaborane is treated (1:1 molar ratios) with sources of the other nucleophilic fragments B.Wrackmeyer Z. Naturforsch. Teil B 1982 37 412. G. Siwapinyoyos and T. Onak Inorg. Chem. 1982 21 156. 19' B. Oh and T. Onak Znorg. Chem. 1982,21,3150. G. K.Barker M. P. Garcia M. Green F. G. A. Stone and A. J. Welch J. Chem. SOC., Chem. Commun. 1982,46. 19' B Al Ga In TI 3 -(CH,)CIB,H Scheme 2 (Reproduced by permission from Inorg. Chem. 1982 21,3150) A. J. Welch [Fe(CNBu'),] and [Co(PEt,),] afford (83) and (84) respectively. 193 In common with (81) (83) and (84) have dodecahedra1 polyhedral frameworks and a 1,4,7-CMCB substitution pattern but in (84) the Co-4-B-8 link is bridged by a [Cb(H)(PEt,),] moiety and the bridging links are themselves bridged Co-48-B by (p-H) and Co-Co by (p-PPh,).Such an arrangement is quite without precedent. 193 G. K. Barker M. P. Garcia M. Green F. G. A. Stone H. E. Parge and A. J. Welch J. Chem. Soc. Ckern. Cornmun. 1982,688. B Al Ga In,TI It has previously been observed that the slipping distortion in icosahedral bis(phosphine)carbaplatinaboranesis less than that in their pentagonal bipyramidal analogues; the results of EHMO calculations have now shown that this is primarily due to the differing elevation angles (ideally 26"and 0" respectively) of substituents bound to the metal-bonded pentagonal faces of the two types of polyhedral ligand.'94 Calculations at this level have also been to explore the reason why [Fe(H)2(Me2C2B4H4)2] adopts a fairly symmetrical sandwich structure (85) (in which H atoms are associated with FeB2 faces) whilst in the isoelectronic molecule Cp2Mo(H) the Cp rings- * y tilted with respect to each other.Not @H H only is the resistance to bending of the ligand-metal-ligand angle significantly greater in bis(borane) complexes than in analogous bis(Cp) species but in addition the frontier orbitals of the molecule are less localized on the metal atom in the former so that the cost in energy of bending is not offset by strong metal-hydrido- bonding. In fact bending in bis(boranes) only occurs when demanded by small cage-bridging functions such as OMe.'96 Calhorda and Mingos"' also analyse the bonding in molecules (86)and (87) in which a BH Sn or Ge unit occupies a wedge h h # (86) (87) (Reproduced by permission from J.Am. Chem. SOC.,1982,104,5987) 194 M. J. Calhorda D. M. P. Mingos and A. J. Welch J. Organornet. Chern. 1982,228 309. 195 M. J. Calhorda and D. M. P. Mingos J. Organornet. Chern. 1982 229 229. 196 V. Subrtova K. Maly V. Petricek and A. Linek Acta Crystallogr. Sect. B 1982,38 2028. A. J. Welch position between two cages fused at a common iron vertex {analogues of (86)in which FeCp Co(PEt,), and Pt(PEt,) fragments replace CoCp have also recently been reported}. 19' Consistent with the previous analysis the major interaction involving the wedge ligand is found to be with equatorial atoms of the cages and not with the central metal. In agreement the e.s.r. and magnetic data for [(Me2C2B4H4)Fe-FeLZ] (L2 = 2thf or (OMe)zC2H4),(88) suggest little direct bonding between the metal centres in spite of a crystallographically determined Fe-Fe length of only 2.414(4) A for the (OMe),CZH4 complex.*98 Species (88) are believed to be intermediates in the oxidative fusion of carbaboranes.2RzCZB4H5-FeCI B (85) 5(88) -% Me4C4B8H8 (88) (Reproduced by permission from J. Am. Chem. SOC.,1982,104 5983) It has been dem~nstrated'~~ that the fusion is intramolecular that the conversion (85)+(88)occurs only in fairly basic solvents and that (85)or its cobalt analogue [Co(H)(Me2C2B4H&] can be rapidly converted into the tetracarbon product (presumably via (88)or analogue} by traces of FeCl,. Oxidation of [7,8-CZB9Hl2]- with chromic acid yields two isomers of C4B 18H22. One of these had previously been shown to consist of coupled nido-C2B9 polyhedra and now structural studyzo0 of the other reveals B-B linked claso-C2Blo and nido-CzBs units.Electronic differences between borane and carbaborane transition-metal com- plexes and their formally analogous Cp complexes have been noted above. Hanusa has recently pointed out201 that a variety of experimental evidence suggests that the electronic and especially the steric requirements of the [7,8-C2B9Hl ligand are more realistically mimicked by C,Me5- rather than C5H5-. The species [Co( 1,2-C2BsH11)2]- readily prepared from [7,8-C2B9H11]2- {an unfortunate consequence of the accepted numbering system for heteroboranes is 19' G. K. Barker M. P. Garcia M. Green F. G. A. Stone and A.J. Welch J. Chem. SOC., Dalton Trans. 1982 1679. R. N. Grimes R. B. Maynard E. Sinn G. A. Brewer and G. J. Long J. Am. Chem. Soc. 1982 104,5987. R. B. Maynard and R. N. Grimes J. Am. Chem. SOC.,1982,104,5983. V. Subrtova A. Linek and J. Hasek Actu Crystullogr Sect. B. 1982,38 3147. T. P. Hanusa Polyhedron 1982 1 663. 19' B Al Ga In TI 59 that it might be supposed that the positions of the carbon atoms in precursor and product are substantially different but this is not so-see (89) and (90)} was one of the earliest carbametallaboranes to be synthesized following recognition of the Cp-/C2B9Hll2- analogy by Hawthorne in the mid 1960's. A previous structural study of its Cs' salt suffered from C/B disorder but now similar study of the Et,NH' salt reveals a staggered C-cisoid geometry.20z Thirteen halogenated deriva- tives (containing 1to 6 halogen atoms) of [Co(1,2-C2B9Hll)]- have been prepared identified by n.m.r.and analysed by capillary isotachoph~resis.~~~ 2-7 lo@4 1 2 (89)[7,8-C2B9H1 1]2-framework "10' The sandwich structure of [Co( 1,2-C2B9H1 ,),I-had previously been extended to the triple-and quadruple-decker systems [(C2B9Hll){Co(C2B8H10)},,-Co(C2B9Hl1)]-(n+ 1)with n = 1and n = 2 respectively. Recent ~t~die~~~~*~~~ by Volkov Dvurechenskaya and co-workers now claim to have lengthened these systems to n = 3 n = 6 and n = infinity. Structural analysis of the di- and tri-cobalt compounds showed that the chains necessarily spiralled as they were extended simply because the bridging functions (9 1) have metallabonded pen- tagonal faces that are adjacent (non-parallel).These are afforded by the formal removal of BH2+ units from [1,2-C2BlOHl2] a procedure that is relatively facile because BH adjacent to two CH sites is relatively acidic. However Hawthorne and Busby have now reportedzo7 a high yield degradation (KOH in the presence of crown ether) of [1,12-C2Bl0Hl2] to [2,9-C2BgHl2]-. Reaction of this with CoCI in the presence of KOH affords [2-Cp-2,1,12-CoC2B9Hll] which formally contains the [2,9-C2BgHl1I2- ligand (92). The relationship between (89) and (91) is the same as that between (92) and the as yet hypothetical bridging unit (93). Were (93) to ultimately yield to synthesis linear analogues of the spiral extended systems are feasible.'O' L. Borodinsky E. Sinn and R. N. Grimes Inorg. Chem. 1982.21 1686. '03 L. Matel; F. Macasek P. Rajec S. Hermanek and J. Plesek Polyhedron 1982 1 511. '04 M. Kovel D. Kaniansky L. Matel. and F. Macasek J. Chromatogr. 1982 243 144. *05 V. V. Volkov and S. Ya. Dvurechenskaya Koord. Khim. 1982,8,263. '06 S. Ya. Dvurechenskaya V. V. Volkov S. V. Tkachev and L. S. Den'kina Zh. Neorg. Khim. 1982 27 1740. '" D. C. Busby and M. F. Hawthorne lnorg. Chem. 1982 21,4101. A. J. Welch [2,9-C2B9H12]- is also the starting point for the synthesis of [2,2-(PPh3),-2-H- 2,1,12-RhC2B9Hll] reported to afford faster rates of hydrogenation of alkenes (and to be more stable under catalytic conditions) than its 3,1,2-RhC2B9 or 2,1,7- RhC2B9 isomers.The 3,1,2-RhC2B9 species reacts with sulphuric acid to replace the hydrido H by SO4 and with nitric acid to replace (3-Pqh3-3-H) by 3,3-NO3. Both the monodentate bisulphate (94) and the bidentate nitrate (95) were previously known but now their chemistries have been explored,208 the emphasis lying on reactions at the metal vertex. Several new carbarhodaboranes have thus been prepared. Notably (94) cleaves dihydrogen to regenerate its precursor and sulphuric acid reacts with phenylethyne to afford the zwitterionic metallacyclopentadiene (96) and reacts with sodium cyanide to produce the tetramer [3-PPh3-3-(p-CNj- 3 1,2-RhC2B9H11], (97) which has linear cyano-bridges and a non-planar (RhCN) moiety. Crystal structures of (96) and (97) are reported.With donor ligands L (L = CO or PPh,) (95 j affords [3-PPh,-3-L-3-N0,-3,1,2-RhC2B9Hll], containing the relatively uncommon monodentate NO ligand. When L = PPhMe, however the PPh group of (95) is substituted and the nitrate remains bidentate. Metal substitution reactions involving [3,1 ,2-T1C2B9H1 1]-and either bis(arene)Fe" salts or [(arene)RuCl2l2 aff ord209 an alternative route to species [3-arene-3,1,2-MC2B9Hll] (M = Fe or Ru) analogues of which have previously been prepared by direct insertion; the expected closo-geometry of [3 -(q6-mesity-1ene)-3,1 ,2-FeC2B9H1 1] was confirmed by crystallographic analysis. Exopolyhedral Chemistry of Carbaboranes.-A number of derivatives of [3 -Cp- 3 1,2-FeC2B9H1 which have functional organic groups (CH20H CHO COOH COMe and CH2COOH) substituting at the 1-C cage atom have been prepared and their chemistries studied.210 With respect to the organic group the [3-Cp-3,1,2- FeC2B9HI0]unit is found to be a weaker electron acceptor than its cobalt analogue.*08 W. C. Kalb Z. Dernidowicz D. M. Speckman C. Knobler R.G. Teller and M. F. Hawthorne Inorg. Chem. 1982,21,4027. '09 T. P. Hanusa J. C. Huffman and L. J. Todd Polyhedron 1982 1,77. 'lo L. I. Zakharkin V. V. Kobak A. I. Yanovsky and Yu. T. Struchkov J. Organomet. Chem. 1982 228 119. B Al Ga In Tl 61 An earlier paper from the same group reports211 full details of the synthesis of 1] [9-0rg-1,7-C2B loHl 1],and [2-0rg- 1,12-C2B10H1 [9-0rg-1,2-C2B10H1 1] by reac- tion of the appropriate B-iodo-compound with Grignard reagents.(R= Me Complexes [l-{Ir(CO)(PPh,)(RCN)}-7-Ph-1,7-C2BloHlo] or Ph) have been shown212 to be effective catalysts in the homogeneous hydrogenation of activated alkenes and alkynes. It is believed that dihydro-species [1-{Ir(CO)-(PPh3)(RCN)(H)2}-7-Ph-1,7-C2BloHlo] are intermediates in such reactions. The geometry of the dihydrides is given in (98). With substituted alkenes and alkynes 0 such complexes undergo insertion (into a Ir-H bond) reactions to afford stable hydridoalkyl and hydridoaryl compounds often as isomeric mixtures.’13 These complexes are thermally labile and readily undergo reductive elimination to yield the reduced hydrocarbon. Exclusively cis- alkenes are produced from alkyne hydrogenation.Stereospecificity is also noted214 in the addition of the carbaboranecarbenes [1-CH2-1,2-C2B10Hll] and [1-CH2-1,7-C2B10Hll] (employed as their diazo-compounds) to alkenes.* With trans- alkenes derivatives of trans- cyclopropane are given and in this sense the carbaboranecarbenes behave similarly to phenylcarbene. With cis-alkenes however the major products are derivatives of cislanti-cyclopro- pane whereas similar treatment of phenylcarbene yields an isomeric mixture containing more of the cislsyn-product. Cyclometallation reactions of carbaborane derivatives reported last year for rhenium have now been extended to manganese affording products with a B-Mn bond.215 C-Hg216 and B-Hg bonds in carbaborane derivatives tend to be relatively weak and therefore of synthetic utility.Thus Se or Te readily inserts into a B-Hg bond of (C2B10H11)2Hg to yield ca. 60% of [(C2BloHll)-#-Ig-Se/Te-(C2BloHll)]. Mercury-free products (C2B 10H11)2Se2 and (C2B loHl l)2Te are also rep~rted.~” Lanthanide metals can also substitute mercury in C-and B-carbaboranyls affording solvated di- or tri-valent C-or B-bonded products.218 ’I’ L. I. Zakharkin A. I. Kovredov V. A. OI’Shevskaya and Zh. S. Shaugurnbekova J. Organomet. Chem. 1982,226,217. 212 F. Morandini B. Longato and S. Bresadola J. Organomet. Chem. 1982 239 377. 213 B. Longato and S. Bresadola Inorg. Chem. 1982 21 168. 214 S. L. Chari S.-H. Chiang and M. Jones jun. J. Am. Chem. SOC.,1982 104 3138. V. N. Kalinin A. V. Usatov I. A. Popello and L.I. Zakharkin Zzv. Akad. Nauk SSSR Ser. Khim. 1982 1433. 216 A. V. Medvedev and V. I. Pakhbrnov Koord. Khim. 1982,8,627. 217 V. I. Bregadze V. Ts. Kampel A. Ya. Usiatinsky 0. B. Ponomareva and N. N. Godovikov J. Organomet. Chem. 1982,233 C33. 218 G. Z. Suleimanov V. I. Bregadze N. A. Koval’chuk and I. P. Beletskaya J. Organomet. Chem. 1982,235 C17. * In reference 214 there appears to be an error in Table 1 the final column of which should presumably be headed ‘cislanti-cyclopropane’. A. J. Welch 2 Aluminium Evidence is presented for the presence of aluminium as Alo in the TiC13/LiAlH4 The new ternary phases NbZnAl and TaZnAl have been synthesized and their crystal structures determined to belong to the Friauf-Laves type.220 A new high-pressure modification of SrA1 has been prepared and shown by powder XRD to have a MgCu structure.221 A1S4 Gas, and AlGe tetrahedra share common vertices to form three-dimensional networks in the crystal structures of BaAl,S, BaGa2S,,222 and Ca3AlGe,223 respectively whereas vertex sharing of AlAs units leads to infinite chains in Ca,AlAs, and discrete edge-sharing tetrahedra yield isolated A12Sb6 units in Ba,A1Sb3.,, Using split-valence basis sets (6-21G 3-21G and 3-21G*) Hehre et al.have computed the equilibrium bond distance in AlH3 (D3hsymmetry) to be 1.601 1.599 and 1.587& re~pectively,~~~.~~~ ab initio MO methods have also been employed227 to study model 0x0-alkyl and carbene complexes of molybdenum to which A1H3 is bound as these species are possible intermediates in alkene metathesis reactions.The stimulus for such studies comes from the related experimental work of Osborn’s groups who last year described metathetical reactions involving oxo- molybdenum species and who more recently report228 that the activated tungsten complexes (99) and (100) (X = C1 or Br) efficiently catalyse the metathesis of cis pent-2-ene into but-2-enes and hex-3-enes. The Ga analogue of (99) is similarly active and has a lifetime (X = Br) exceeding 24 h. Synthetic and catalytic on the system [MoC1(NO)(CO)2(PPh3)2]/RAlC12 (R = Me or Et) have shown that it too represents a long-lived highly active catalyst for alkene metathesis. The activation of carbonyl ligands by interaction of the carbonyl oxygen atom with Lewis acids is well established and heats of reaction for [CpMn(CO),] and AlBr, and [CpMn(CO),(PPh,)] or [CpRe(CO),] with AlBr or GaCl, have been AlCl and AlBr react with [MeMn(CO)J to afford the cyclic species 219 R.Dams M. Malinowski and H. J. Geise Transition Met. Chem. 1982 7 37. 220 A. Drasner and Z. Blazina 2.Nuturforsch. Teil B,1982,37 1225. 22 1 G. Cordier E. Czech and H. Schafer 2.Naturforsch. Ted B 1982,37 1442. 222 B. Eisenmann M. Jakowski and H. Schafer Mater. Res. Bull. 1982,17 1169. 223 G. Cordier and H. Schafer Z. Anorg. Allg. Chem. 1982,490 136. 224 G. Cordier G. Savelsberg and H. Schafer 2.Nuturforsch. Teil B 1982,37 975. 225 M. S. Gordon J. S. Binkley J. A. Pople W. J. Pietro and W. J. Hehre J. Am. Chem. Soc.1982 104,2797. 226 W. J. Pietro M. M. Franc] W. J. Hehre D. J. De Frees J. A. Pople and J. S. Binkley J. Am. Chem. SOC.,1982,104 5039. 227 S. Nakamura and A. Dedieu Nouo. J. Chim. 1982,6 23. 228 J. Kress M. Wesolek and J. A. Osborn J. Chem. SOC., Chem. Commun. 1982 514. 229 K. Seyferth and R. Taube J. Organomet. Chem. 1982 229 275. 230 E. N. Gur’yanova A. G. Ginzburg E. S. Isaeva V. N. Setkina and D. N. Kursanov Dokl. Akad. Nauk SSSR. 1982,262 1389. B Al Ga In,TI (101) (X = C1 or Br) but it was unclear until recently whether or not the Lewis acid actually induced the methyl migration (carbonyl insertion) or simply intercepted the co-ordinatively unsaturated intermediate (102). A ‘stopped-flow’ kinetic study has now indicated that the former is indeed the case.231 AlCl and AlMe clearly play important (though not well understood) roles in the coupling of carbonyl and carbyne ligands when [W(CH)(Cl)(PMe,),] reacts with CO in their presence to afford232an q2-HC=COAlX3 complex (X = C1 or Me) characterized by a crystallo- graphic study of the chloro-derivative (103).(103) (Reproduced by permission from Organometallics 1982,1,766) Reaction of the methylene-bridged complex (104) with thf affords2, two para- magnetic products (detected by e.s.r.) [Cp,TiCl(thf)] and the dititanium species (105). This latter complex is thought to be implicated in methylene exchange reactions between (104) and alkenes of the type CH2=CR2. 231 T. G. Richmond F. Basolo and D. F. Shriver Znorg.Chern. 1982 21 1272. 232 M. R. Churchill H. J. Wasserman S. J. Holmes and R. R. Schrock Organornetallics 1982,1 766. 233 P. J. Krusic and F. N. Tebbe Znorg. Chern. 1982 21 2900. A. J. Welch C CpzTi,/C\ /TiCp2 Cp2Ti( )A1Me2 C1 ci (104) (105) LiAlH4 is to display ambivalent co-ordination behaviour in electron- transfer reactions since reaction of pyrazine with LiAlH4 yields the radical (106) in which Li' is co-ordinated whereas quinoxaline and 4,4'-bipyridine (generally L) afford [(H2AI)L(AlH2)]~ containing co-ordinated +AIH2. AlH3 reacts with Cp2YC1 in Et20 to afford [(Cp,YC1)2AIH3.0Et2] whose crystal- line structure (107) involves quasi-5-fold co-ordination of the aluminium atom (107) (Reproduced by permission from J. Organornet.Chem. 1982,235 151) 234 W. Kaim Angew. Chem, Int. Ed. En& 1982 21 141. B Al Ga,In TI 65 since the solvated A1H3 unit is weakly bonded 3.007(7) A to a p-C1 of the (CP~YC~)~ In (107) the A1 atom is linked to different Y atoms'viu hydrogen bridges thus forming a polymeric chain whereas in (108) and (109) the double H-bridging is intramolecular. Compounds (108) and (109) have been tested as potential catalysts for the isomerization of hex- 1-ene to (predominantly truns ) hex-2-ene and only complexes (108) which involve at least one terminal H were found to be effective. A possible mechanism is HX Ti( 'Al' QH' (108) X,X' = H halide alkyl (109) n = 1-3 Calcium alkoxyalanates Ca[AlH4-,(OR),]2 {n = 1-3 R = Pr' Bu' But i-C5Hll cy MeO(CH2)2} are by alcoholysis of Ca(AlH,), and structures are proposed in which the Ca atoms are linked to each A1 atom by (2n -2) alkoxy-bridges and (6 -2n ) H-bridges.A following paper238 describes improved synthesis of the alkoxyalanates and a third239 their reductive properties towards a variety of organic reagents. Most effort centred upon Ca[AlH,(OR),] (110)which has a good balance of stability solubility and hydride content and it was concluded that (110) has a reducing power comparable with more active species such as LiAlH,. The preparation of anhydrous AlF from reaction of Al(OH) with SF under mild conditions is de~cribed.'~' Thermodynamic data for Na3A1F6(s) Na,Al,F,,(s) and NaAlF,(l) have been established,241 such species constituting part of the basic electrolyte in the electrolytic genera tion of aluminium.Three syntheses of CsMAIF6 (M= Cu or Zn) have been and basic crystallographic parameters established. Powder data for the new minerals Ag2MAlF7 Ag2MGaF7 and Ag2M'InF7 (M = Mg Mn Co Cu or Zn; M' = Mg Co or Zn) show that all are isostructural with Weberite Na2MgA1F7,243 whilst a single crystal study of Ba MAlF9 (M = Zn,244 Co Ni or Mg245) reveals that four Al/ZnF6 octahedra are linked by vertices to yield tetrameric units further connected to form a stepped network. 235 E. B. Lobkovskii G. L. Soloveichik A. B. Erofeev B. M. Bulychev and V. K. Bel'Skii J. Organomet. Chem. 1982,235 151. 236 B. M. Bulychev E. V. Evdokimova A. I. Sizov and G. L. Soloveichik J. Orgunornet. Chem.1982 239 313. 237 S. Cucinella G. Dozzi,and G. Del Piero J. Organornet. Chem. 1982 224 1. 238 G. Dozzi S. Cucinella and M. Bruzzonne J. Orgunomet. Chem. 1982 224 13. 239 S.Cucinella G. Dozzi and M. Bruzzonne J. Organomet. Chem. 1982 224 21. 240 V. P. Shendrik 0.D. Lyakh and L. M. Yagupol'skii Ukr.Khim. Zh. 1982,48 1108. 24 1 A. Serten K. Hamberg and I. Maeland Acta Chem. Scund. Sect. A 1982 36 329. 242 T. Fleischer and R. Hoppe J. Fluorine Chem. 1982,19 529. 243 J. Koch C. Hebecker and H. John 2. Nuturforsch. Teil B,1982 37 1659. 244 T. Fleischer and R. Hoppe 2.Anorg. Allg. Chem. 1982,492 83. 245 T. Fleischer and R. Hoppe Z. Anorg. Allg. Chem. 1982 493 59. A. J. Welch For years AlI and Gar3 have been assigned to be isostructural in the crystalline phase with 1111,.Accurate structural on all three iodides have now shown however that whilst GaI and InI exist as discrete dimers M216 (lll) AlI has the infinite chain structure (112).n n 2.~78 . Upper parameters M = In Lower parameters M = Ga (Reproduced by permission from Angew. Chem. Int. Ed. Engl. 1982 21 386) A1 n.m.r. spectroscopy has been used to investigate the dissociation of AlCl into AlC14- and solvated A1Cl2+ and/or A1C12+ in various ether solutions and additionally has revealed the existence of exchange proce~seq.~~~ Thermodynamics of the reactions NiC12(s) + MCI3(g) + NiMCIS(g) and NiC12(s) + M2C16(g) -B NiM2C18(g) (M = A1 or Ga) have been established248 and compared with the results of a previous study in which M = In.It is concluded that NiGaC1 is the least stable member of the NiMCl series and that all three molecular structures within each series are similar. The a-bonded zwitterionic complex (Me4C4)-A1Cl3 formed by condensation of two but-2-yne molecules in the presence of AlCl is a convenient source of the Me4C4 ligand in reaction with Ni(CO) in CH2C12 and (Me4C4)NiC12 results. Under appropriate reaction conditions AlC13 Ni(C0)4 and but-2-yne react in CH2C12 to afford [(Me4C4)Ni(Me6C6)]2Alc14? in which cyclodimerization and cyclotrimerization of the alkyne has Solid AlCl promotes the sym- metrical cleavage of S4N4to yield S2N2(AlC13)2 (113) shown by a crystallographic 24b R. Kneip P. Blees and W. Poll Angew Chem. In?.Ed. Engl. 1982,21 386.247 H.Noth R. Rurlander and P. Wolfgardt Z. Naturforsch. Teil B 1982,37,29. F. P. Emmenegger P. Favre and M. Kluczkowski Inorg. Chern. 1982,21,2934. 249 H. Hoberg and H. J. Riegel J. Organomet. Chem. 1982,229 85. B Al Ga,In TI CI2 CI3 (Reproduced by permission from Angew. Chem. Int. Ed. Engl. 1982,21,634) study to possess a planar S2N2ring and to have a rather short S..-C1-2 contact distance.250 In extending their recent studies on the AlBr,/MeCN system to AlCl, Dalibart et al. find evidence,251 from i.r. Raman and 35Cl and 27Al n.m.r. spectroscopies for AlCl,- complexes of [A1(MeCN),l3’ [AlC1(MeCN)5]2t and [AlCl,(MeCN),]’ although the stereochemistry of the last cation remains unclear. Evidence for the new species [A1(MeCN),l3’ is presented.A later paper2s2 examines competition reactions between MeCN and NMe,Cl MeN02 and water with respect to complex formation with AlCl,. With pyridine (py) AlCl forms not only a simple 1 1adduct but also 2 1 and 3 1 (N :Al) systems now identified crystallographically as trans -[A1Cl2py4]AlCl4 and rner-[A1C13py3] re~pectively.~’~ The A1C13/n-butylpyridinium chloride (bpc) system represents the archetypal anhydrous molten fused salt system. Such melts are inter alia useful media for the study of the co-ordination of transition-metal ions by C1- and data pertaining to FeC142- FeC1,- and NiC1,2- have recently appeared.254 However the AlCl,/bpc system has practical limitations including a rather narrow ‘electrochemical window’ (the difference between anodic and cathodic decomposition potentials) that have restricted its applicability.In exploring new systems it has been shown that dialkyl- imidazolium chloroaluminium have wider cathodic limits and that the AlC13/1-n-butyl-4-(dimethylamino)pyridinium chloride has a potential range shifted to ca. 700 mV more negative that AlCl,/bpc. An alternative melt is that afforded by NaCl and AlCl, and the solubility (as a function of temperature) of NaCl in this system has been Anodic oxidation of sulphur dissolved in the NaC1/A1Cl3 melt had previously yielded 250 U. Thewalt and M. Burger Angew. Chem. Int. Ed. Engl. 1982 21,634. 251 M. Dalibart J. Derouault P. Granger and S. Chapelle Znorg. Chem. 1982 21 1040. 252 M. Dalibart J. Derouault and P.Granger Znorg. Chem. 1982 21 2241. 253 P. Pullman K. Hensen and J. W. Bats Z. Narurforsch. Teil B 1982,37 1312. 254 T. M. Laher and C. L. Hussey Inorg. Chem. 1982 21,4079. ”’ J. S. Wilkes J. A. Levisky R. A. Wilson and C. L. Hussey Inorg. Chem. 1982,21 1263. ”‘ G. T. Cheek and R. A. Osteryoung Znorg. Chem. 1982,21,3581. 257 H. A. Hjuler A. Mahan J. H. von Barner and N. J. Bjerrum Znorg. Chem. 1982 21,402. 68 A. J. Welch species in which the formal oxidation states are +4 +2,+1 and +$and now evidence is for the anodic synthesis of lower oxidized species S4+ S8+,and SI2+ in a 37 :63,?ole ratio melt (NaCl :AlCl,) at 150 "C. The reduced ion S3- exists in CsCl/AIClj melts and has been shown by e.s.r. study to be coupled to an AlCl or AlC1,- unit probably uia the central 1.r.analysis of the KC1/A1C13 melt reveals the presence in it of A12C17- ions,26o and vibrational spectra (i.r. and Raman) and normal co-ordinate analysis of A12C17- A12Br7- and A1217- in the solid state have been reported.261 Consistent with the results of previous studies it is suggested that the symmetry of these anions is higher in the liquid (linear Al-X-A1 bridge) than in the solid (bent AI-X-A1 bridge) phase. The thermodynamics of the reaction between AIF and molten NaCl or KCl at 810 "C (yielding A1C13 and AlF,-) have been investigated,262 and the gas-phase structures of LiA1F4 and MgAIFs examined by extended-basis set MO calcula- tion~.~~~ By repeating Li and MgF fragments about A1 from face- to edge- to corner-bridging geometries it is concluded that (i) the (experimentally observed) edge-bridged structure is most stable (ii) the less stable structures are not sufficiently metastable to be likely to be observed and (iii) the potential energy curve in the region of the edge-bridged structure is shallow enough to allow some distortion to be possible.In the solid state the cations in LiAlCl and NaAlCl are surrounded by respec- tively 6 and 7 near C1 atoms from adjacent AlCl,- anions. At 293 K Li --C1 distances range from 2.475(7) to 2.841(7)A and Na -* C1 is 2.788(4) to 3.229(3)A with increasing temperaturi these lengths increase by ca. 0.025 8 per 100 "C. No change in AI-Cl distances occurs up to 364 K (Lithium salt) and 393 K (Sodium In Cu(AlCl& two A1C14 tetrahedra are linked to each copper by four strong C1 bridges (Cu-Cl 2.29-2.31A) in a square plane.A pair of weak Cu --C1 contacts 2.951 A completes a tetragonal co-ordination sphere about each Cu atom leaving one C1 per AlCl non-bridging. The Al-C1 lengths show an excellent inverse relationship to the degree of bridging e~perienced.~~' Unfortu-nately Ono et al. do not acknowledge that c~(AlC1~)~ had already been accurately studied by single crystal XRD two years previously.266 Neutron powder diffraction of a-TiA1,C18 (the low-temperature modification) reveals a chain structure in which adjacent Ti atoms are linked via distorted triple corner sharing with two AICl tetrahedra (1 14). Vibrational frequencies for TiA12C18 correlate well with the reduction in symmetry (Td in AlCl,-+ C3uin TiA12C18) and this method is also used to provide supportive evidence for local CZusymmetry at A1 in [(q-C6H6)Ti(A1C14)2].Co-incidentally single-crystal XRD study of the arene complex has been published,268 unequivocally confirming the predicted structure (115).The 258 R. Fehrmann N. J. Bjerrum and E. Pederseii Inorg. Chem. 1982 21 1497. 2s9 R. Fehrmann S. von Winbush G. N. Papatheodorou R. W. Berg and N. J. Bjerrum Inorg. Chem. 1982,21 3396. 260 A. I. Morozov and 0.A. Solovkina Zh. Neorg. Khim. 1982 27 326. 26' A. Manteghetti and A. Potier Spectrochim. Acta Part A 1982 38 141. 262 R. V. Chernov Zh. Neorg. Khim. 1982 21 1162. 263 L. A. Curtiss Inorg. Chem. 1982 21,4100. 264 E. Perenthaler H. Schulz and A. Rabenau Z.Anorg. Allg. Chem. 1982 491 259. 265 N. Kitajima H. Shimanouchi Y. Ono and Y. Sasada Bull. Chem. SOC.,Jpn. 1982,55 2064. 266 H. Schafer M. Binnewies R. Laumanns and H. Wachter Z. Anorg. Allg. Chem. 1980,461 31. 267 A. Justnes E. Rytter and A. F. Andresen Polyhedron 1982 1 393. 268 U. Thewalt and F. Stollmaier J. Organornet. Chem. 1982 228 149. B Al Ga,In TI reductive Friedel-Crafts synthesis of arene-transition-metal complexes often yields chloroaluminate anions and two novel such species containing linking oxygen atoms have recently been studied by XRD. In both (116) and (117) the oxygen atoms are trigonally-planar bound to three metals and in (116) the unique aluminium atom is q~asi-5-co-ordinate.~~~ C 13 4 (114) (Reproduced by permission from Polyhedron 1982,1,393) (Reproduced by permission from J.Organornet. Chern. 1982,228 149) U. Thewalt and F. Stollmaier Angew. Chern. Int. Ed. Engl. 1982 21 133. A. J. Welch 2-C1 c1 I c1 ‘A]’ The reactions between Et,AlC13-,(n = 0 1 or 3) and 3,6-di(But)-1,2-benzoquinone afford long-lived radical derivatives in which three kinds of metal- ligand bonding fluctional monodentate non-fluctional monodenate (seen for the first time with aluminium) and bidentate have been observed (e.s.r. spectroscopy) dependent upon reaction conditions.270 Although Kashireninov et al. contend271 that ‘there is currently no direct proof of A102 formation in the gas-phase reactions of A1 atoms with oxygen’ Serebrennikov et al. have reacted A1 (and Ga In and TI) atoms with 0 in an argon matrix at 14 K and have interpreted the i.r.spectra of their products in terms of the formation of MO molecules with cyclic structures of Czv With phenol at 140-150 “C aluminium is to yield (PhO),AlOH which affords the 0-bridged dimer (PhO),A1-O-Al(OPh)2 by elimination of water. This second species can be considered a derivative of an aluminoxane (R,AlOAlR,), whose description in this simple way has recently been It appears that at least for R = Et a more appropriate description is given by the equilibrium of equation (8). (n -1) R2Al(OAIR),-IOAIR2 + (n -l)AlR3 $ R3AI(OAIR),-IOAIR2+ -(AIR& 2 (8) In order to impart selectivity in the reducing properties of magnesium hydrides Goel et ~1.’~~ have prepared the mixed isopropoxy-hydride of magnesium and aluminium [Pr’OMgA1(OPri)zHz] and tentatively assign it the structure shown in (118) (Sol = solvent).Compound (118) is afforded by reaction of equimolar 270 A. G. Davies Z. Florjanczyk E. Lusztyk and J. Lusztyk J. Organomef.Chem. 1982 229 215. 271 0.E. Kashireninov A. D. Chervonnyi and V. A. Piven High. Temp. Sci. 1982.15 79. 272 L. V. Serebrennikov S. B. Osin and A. A. Maltsev J. Mol. Struct. 1982 81 25. 273 I. M. Zerzeva N. L. Voloshin E. V. Lebedev P. L. Klimenko and V. I. Lozovaya Ukr. Khim. Zh. 1982,48,728. 274 A. Wolinska J. Organornet. Chem. 1982 234 1. 275 A. B. Goel. E. C. Ashby and R. C. Mehrotra Inorg. Chim. Acfa 1982,62 161. 71 B Al Ga In,TI amounts of MgH2 and Al(OPr'), and with two equivalents of the latter the alkoxyaluminate Mg[A1(OPri),Hl2 is produced.No structural information for this is given but the possible complexity of such species is demonstrated by the structure advanced276 (on the basis of n.m.r. studies) for Mg2[A1(OEt),], (119). OEt I EtO EtO-Mg-OEt OEt I \/ 'Al' OEt A1 EtO' 'OEt EtO' 'OEt 'Al' OEt )< /\ EtO EtO-Mg-OEt OEt I OEt Examination of the U.V. spectra of aqueous solutions of AIC13 A1(C104), Al(NO3), and A12(S04) of varying concentrations has that (i) the absorption maximum found at ca 240nm for the chloride and perchlorate (and in low concentrations for the sulphate) arise from the charge transfer equation (9) [Al"'( 0H-)(OH2),I2' +[Al"(OH)(OH2)5I2+ (9) (the Al"' di-cation is in equilibrium with [A1(OH2)6]3+) (ii)above 0.1Mthe sulphate bound cation [Al(S04)(0H2)5]' is formed and (iii) no evidence for inner sphere co-ordination of nitrate is found in spite of the absence of an absorption maximum at 240nm.Although solutions of aluminium nitrate do absorb at 240nm the spectra are dominated by a peak at 303nm which is a direct function of NO3- concentration. [A1(OH2),I3' and [Al(OH)(OH,),]*' ions react with HL2- and L3- (H,L = 8-hydroxy-7-{(6'-sulpho-2'-naphthyl-l)azo}quinoline-5-sulphonic acid) to afford A1L(OH2), in which L co-ordinates through its heterocyclic nitrogen and phenolic oxygen atoms.278 Low-temperature Raman spectra of the allums CSAI(SO~)~- 12D20,CsA1(Se0,),.12H20 and C~Al(S0,)~.12D~0 have been fully and self- consistently assigned279 between 300and 1200cm-'.In this region occur the internal modes of and of [A1(OH2)6]3+ and the librational modes of OH2 bound to A13+ and Cs'. For the [A1(OH2),I3+ cation the vl v2,and v5 modes occur at 542 473,and 347cm-' respectively. Current research interest in A1203is centred mainly in two areas-polymorphism studies and heterogeneous catalysis. Over the last two years Saeki et al. have investigated the conditions necessary for the preparation of fine powders of A1203 from vapour-phase reactions of AlCl,. With O2containing about 2-5% H20 AlCl affords280 amorphous A1203below 600 "C mainly y-A1203 at 900 "C and y-and S -A1203 at 1000 "C. Thermolysis of the amorphous phase affords x -A12O3 at 276 N.Ya. Turova N. I. Kozlova and M. I. Yanovkanya Koord. Khim. 1982 8 148. 277 J. F. McIntyre R. T. Foley and B. F. Brown Znorg. Chem. 1982,21 1167. 278 K. Hayashi K. Okamoto J. Hidaka and H. Einaga J. Chem. SOC.,Dalton Trans. 1982 1377. 279 S. P. Best R. S. Armstrong and J. K. Beattie J. Chem. Soc. Dalton Trans. 1982 1655. 280 Y. Shoji R. Matsuzaki and Y. Saeki Bull. Chem. SOC.Jpn. 1982 55,473. 72 A. J. Welch ca. 700 "C teAl2O3 at ca. 800"C and a-A1203 at 1000 "C. Heating r-Al,O pro-duces S (at 900 "C) then @ (at 1000 "C) A1203 the @-phase transforming to A1203 if held at 1000"C. The y to 6 to @ to a thermolysis has aiso been followed (using i.r. spectroscopy) by other workers.z81 q -A120 is affordedza2 as a thin crystalline coating when an aluminium anode is sparked" (150 V 303-353 K 120-300 s).In heterogeneous catalysis alumina is either used as a ~~pp~rt~~~-~~~ or as an active species itself. In its former role pre-treatment of the alumina is sometimes important and in these cases the alumina is clearly more than simply supportive. Thus Cr- Mo- and W-hexacarbonyls on dehydroxylated alumina (alumina calcined at 500°C) can be fully decarbonylated to afford catalysts that are ca. 1000-times more effective in alkene hydrogenation than were the alumina not pre-treated.z86 As an active catalyst in its own right A1203 will for example when dusted onto a glassy carbon electrode strongly absorb compounds such as catechols and catalyse their It is likely that the acid-base character of the alumina surface is an important factor in determining catalytic activity and a recent study2" has probed the acid-base properties of a number of modified A1203 surfaces.Numerous papers on aluminates have been published in 1982 and we here attempt only to identify a few of the more interesting and hopefully more relevant ones. In Na17A1506 there exist discrete chains of five A10 tetrahedra sharing corners. The angles at bridging oxygens are 173(1) and 159.9(7)" and are dis- cussed in terms of possible O(p.rr)-Al(d.rr) In 5 Sr0.4A1203.H20 a structurally new framework is observed,290 being built from rings of three and six tetrahedra. The p-form' of another strontium aluminate SrA1407 has also been characterized by single crystal XRD and a densely-packed three- dimensional (A1407)oo network identified.29' Other aluminates to have been struc- turally studied include PbA1204 ,292 Srl .33Pb0.67A1601 ,294 ,293 Pb8(Pbo.sSro.4)A18021 Nd2Fe15A19038295 A series of and (from neutron powder data) Ba3TiA110020.296 accurate high temperature (295 450 600 750 900 and 1200 K) XRD data sets have been obtained from CuAlO, and refinements have shown non-uniform expansion of the linked A106 Diffraction is by no means the only "' M.I. Baraton and P. Quintard J. Mol. Struct. 1982 79 337. "' M. Yamada and I. Mita Chem. Lett. 1982 759. 283 B. Zhao Y. Zhang L. Duan Y. Xie and Y. Tang Cuihua Xuebao 1982,3 101. 284 E. I. Bogolepova S. B. Verbovetskaya and A. N. Bashkirov Neftekhimiya 1982 22 207. '13' H. Niizuma T. Mori A.Miyamoto T. Hattori H. Masuda H. Imai and Y. Murakami J. Chem. SOC.. Chem. Commun. 1982 562. 286 D. A. Hucal and A. Brenner J. Chem. SOC. Chem. Commun. 1982,830. 287 J. Zak and T. Kuwana J. Am. Chem. SOC.,1982,104,5514. 288 E. A. Paukshtis P. I. Soltanov E. N. Yurchenko and K. Jiratova Collect. Czech. Chem. Commun. 1982,47,2044. 289 M. G. Barber P. G. Gadd and S. C. Wallwork J. Chem. SOC.,Chem. Commun. 1982 516. 290 L. S. Dent Glasser A. P. Henderson and R. A. Howie Acta Crysf. Sect. B 1982,32 24. 291 K.-I. Machida G.-Y. Adachi J. Shiokawa M. Shimada and M. Koizumi Acta Cryst. Sect. B 1982 38 889. 292 K.-B. Plotz and Hk. Muller-Buschbaum Z. Anorg. Allg. Chem. 1982,488 38. 293 K.-B. Plotz and Hk. Miiller-Buschbaum 2.Anorg. Allg. Chem. 1982,491 253.294 K.-B. Plotz and Hk. Muller-Buschbaum Z. Naturforsch. Teil B 1982,37 108. 295 U. Lehmann and Hk. Muller-Buschbaum 2.Anorg. Allg. Chem. 1982,486,45. 296 M. C. Cadee D. J. W. Ijdo and G. Blasse J. Solid State Chem. 1982 41 39. 297 T. Ishiguro N. Ishizawa N. Mizutani and M. Kato J. Solid State Chem. 1982,41 132. * The page numbered 761 of this paper should be read before page 760. B Al Ga,In,TI 73 physical method used to study aluminate structures however; recent papers have illustrated the capabilities of vibrational and of solid-state n.m.r. (27A1299.300 and for aluminosilicates 29Si301) techniques in this respect. The reaction of toluene 3,4-dithiol H2TDT with A1Me3,302 Me2A1C1,303 and A1C13,303 affords TDTAlMe TDTAlCl and the 2,7-dimethyltrianthrene radical cation respectively whereas the nature of the products of the reaction between H2TDT and adducts AlMe3.L depends markedly upon the nature of L.304 For L = HNMe the reaction is straightforward and TDTA1Me.HNMe2 is afforded.When L = NMe, (TDT),A12.2Nhle3 and AlMe3.NMe3 are produced by facile rearrangement of TDTAlMe-NMe,. Using the H,NMe adduct affords an ill-charac- terized polymeric species and when L = OEt the products are solvent dependent. A number of soluble alkoxy- aryl- and alkylamido-derivatives of sodium tetra-amidoaluminate NaAl(NH,), have been synthesized by its reaction with alcohols arylamines and sodium tetrakis(alkylamido)aluminates,respectively. ‘H n.m.r. data are reported for all With the aim of using amphoteric ligands with both metal- and oxygen-binding centres to activate CO and encourage its reduction Labinger Miller and co- workers have synthesized a series of aluminaminophosphines R2PN(R’)AIR’’2 (120).In adjacent communications they show that such ligands to facilitate the formation of CO insertion products reaction of (120) (R = Ph R’ = But R“= Et) with [CpFe(CO),Me] affording306 first (121) {AlNP is a short form of (120)) by co-ordination of the acid centre to 0,then (122) by insertion and thereafter internal nucleophilic attack to yield (123). Compound (123) can be isolated and was characterized by a crystallographic study. Although kinetically favoured it is however thermodynamically unstable over a period of days to yield metallacyclic complexes.With HMn(CO) the same derivative of (120) aff ords307 an analogous complex (124) but use of the derivative with R” = Me yields the unexpected product whose skeleton is shown in (125) and in which the C-4 0-4 ligand has been reduced to an aluminoxyphosphinomethyl function by a second molecule of 298 M. C. Saine E. Husson and H. Brusset Spectrochim. Acta Part A 1982 38 25. 299 W. Gessner D. Miiller H.-J. Behrens and G. Scheler 2.Anorg. Allg. Chem. 1982,486 193. 3oo F. von Lampe D. Miiller W. Gessner A.-R. Grimmer and G. Scheler 2.Anorg. Allg. Chem. 1982 489 16. 301 G.Engelhardt D. Hoebbel M. Tarmack A. Samoson and E. Lippmaa 2.Anorg. Allg. Chem. 1982 484,22. 302 A. A. Carey and E. P. Schram Inorg. Chim. Acta 1982 59 75. 303 A. A. Carey and E.P. Schram Inorg. Chim. Acta 1982,59,79. 304 A. A. Carey and E. P. Schram Inorg. Chim. Acta 1982 59 83. 305 0.Kriz F. Mares and B. Casensky Collect. Czech. Chem. Commun. 1982 47 384. 306 J. A. Labinger and J. S. Miller J. Am. Chem. SOC. 1982 104 6856. 307 D. L. Grimmett J. A. Labinger J. N. Bonfiglio S. T. Masuo E. Shearin and J. S. Miller J. Am. Chem. SOC.,1982,104,6858. 74 A. J. Welch (120). In (125) the quasi-octahedral co-ordination at Mn includes the H atom of an Al-bound methyl group. OHA? (CO)dMn<I N /C-p’ H (1241 (125) (Reproduced by permission from J. Am. Chem. SOC.,1982,104,6858) The radicals (126) and (127) in which the A1 atoms are in 6-positions with respect to the radical centre have been generated and have been studied by em.In contrast to AIMe, HAIBU‘~ affords radical complexes with N-heterocycles such as pyrazine and 2,2’-or 4,4’-bipyridine by single electron transfer reactions.309 /,O -AlMe3 Mek-CN-AIMe3 Mek-C The effect of adding a hydrogen atom to A1 in AlCH has been studied by ab initiu MO calculations with an STO-3G basis set. In agreement with a previous investigation the AI-C bond in AICY is found to be essentially single (optimized length 1.948 A) but this bond is substantially shortened (to 1.684A) by addition of H to Al and thus gains some double bond character. Since H-addition reduces 308 S. Brumby I. Chem. Soc. Chem. Commun. 1982,677. 309 W.Kaim,2. Naturforsch. Teil B 1982 37 783. 75 B Al Ga In TI the charge on the metal it is suggested that a highly electronegative substituent might lead to a full Al=C double bond.310 In contrast both BCH2 HBCH are calculated to have B=C double bonds.The conclusion that ‘Boron should more readily form double bonds with carbon than will aluminium’ also results inter alia from experimental study of the gas-phase positive-ion chemistries of BMe and A1Me,.3 Aluminium trialkyls react with crown ethers (CE) to afford stable isolable complexes312 {crystal structures of (A1Me3)2 (dibenzo- 18-crown-6) and (A1MeJ4 (15-crown-5) are reported} that encourage the solubility of many species MX (M = wide range of metal-containing cations; X = wide range of anions) in aromatic solvents thereby ultimately aff or‘ding M[A1R3X] and M[A12R6X].Although not obtained via a CE adduct “Me,] [A1,Me6(MeC00)] and Rb[Ga2Me6(MeC00)] have been prepared and structurally analy~ed.~~~ The overall anion geometry is similar for both species and is shown for the Ga complex in (128). (128) (Reproduced by permission from Orgunometullics 1982,1 1179) 13 C n.m.r. studies of tricyclopropylaluminium dimer have concluded that the most probable mechanism for bridge-terminal ligand exchange proceeds via the singly bridged intermediate (129). Similar study of Ga(c-C3HS) and I~(C-C,H~)~ c-C~H~ H c-C~H~ HA1 g A15c-C3H5 c-C3H5’ c-C~H~ (129) as functions of temperature and of concentration have been interpreted in terms of monomer4imer equilibrium and thus for the first time are formally saturated groups suggested to act as sufficiently strong bridging functions between two Ga 310 C.M. Cook and L. C. Allen Organometallics 1982 1 246 311 M. M. Kappes J. S. Uppal and R. H. Staley Organometallics 1982 1 1303. 312 J. L. Atwood D. C. Hrncir R. Shakir,M. S. Dalton R. D. Priester and R. D. Rogers Organometallics 1982,1 1021. 3’3 M. J. Zaworotko R. D. Rogers and J. L. Atwood Organometallics 1982,1 1179. A. J Welch or two In A12(o-tolyl) has the usual dibridged geometry in the crystalline phase,315 but the A1 * * A1 distance 2.817(2)& is rather long and may be related to the previously established low stability of the dimer form. In contrast tribenzylaluminium has uniquely a monomeric solid state geom- etry.,16 However the co-ordinative unsaturation of the metal is mitigated some- what by an interesting moderately strong a-interaction between its vacant 3p orbital the 2p(7r) orbital of only one carbon atom (an ortho one) of a phenyl ring of an adjacent molecule.The A1 -.C distance is 2.453(6) A and A1 -C-C angles are ca. 95 and 98". In consequence the A1 atom is located ca. 0.48 A out of its formal co-ordination plane in a direction towards the unique phenyl-C. Al(p-C5H5)Me2 has a similar to its gallium analogue and to In(p- C,H,(V~-C,H~)~ in that the p-C,H functions 1,3-bridge MR2 fragments in infinite chains. The bridging Al-C bonds are asymmetric 2.203(2) and 2.248(2) A and there is clear indication of 7r-bond localization in the C-4-C-5 bond 1.355(3) A of the bridging ligand. In [(Me5C,)A1(R)(p-C1)I2 (R = Me Et or Pr') the penta- methylcyclopentadienyl ligands are only q3-bonded to the metal3l8 {the structure of the R = Me derivative is shown in (130))thus representing further examples of slipped ring structures.Although the uncoordinated C-C ring distances are some- what shorter than C-1-C-5 and C-2-C-5 there is no discernable folding of the C5 pentagon. In parallel the bonding within these species has been studied by Fenske-Hall MO calculations. (130) (Reproduced by permission from Organometallics 1982 1 799) KH reacts with Al(CH,SiMe,) at 70 "C to produce K[AI(CH,SiMe,),H] but there is inconclusive evidence that this product can be pyrolysed to afford K[A1(CH2SiMe3),] by reductive elimination. A new synthetic route to Al( CH2SiMe3) is reported.31 314 R. D. Thomas and J. P. Oliver Organometallics 1982 1 571. 315 M. Barber D. Liptak and J. P. Oliver Orgunometalfics 1982 1 1307. 316 A. F. M. M. Rahman K. F. Siddiqui and J. P. Oliver Organometallics 1982,1 881. 317 B. Tecle P. W. R. Corfield and J. P. Oliver Znorg. Chem. 1982 21,458. 318 P. R. Schonberg R. T. Paine C. F. Campana and E. N. Duesler Orgunometuflics 1982 1 799. 319 0.T. Beachley jun. C. Tessier-Youngs R. G. Simmons and R. B. Hallock Znorg. Chem. 1982 21 1970. B Al Ga In TI Evidence is to support the view that the transition-state complex derived from reaction of two equivalents of AIR3 (R = alkyl) with one equivalent of ketone is better described by (131) than by (132). Following their previous study of the hydroalumination of ethyne Gropen and Haaland have investigated theoretically the reaction between AlH3 and ethene.321 The reaction scheme is shown in (133).In a possible first step the symmetric .rr-complex (b) is formed (hE = -36kJmol-' relative to components at infinite separation). Transformation of this to the asymmetric transition state (c) is followed by Al-H bond breaking to yield EtAlH,. The overall activation energy for this process is ca. 50 kJ mol-' considerably higher than the experimental estimate. AE =-36kJmol-l AE = 0 1 H H160A '!I AEf-123 kJ mol'l (133) (Reproduced by permission from Acta Chem. Scand. Sect. A 1982,36,435) When A1 atoms are allowed to react with ethene and with ethyne in inert gas matrices at -4 K the .rr-bonded complex (134) (which additionally has an interac- tion between a half-occupied A1 3p orbital and the ligand .rr* MO) and theu-bonded 320 E.C. Ashby and R. S. Smith J. Urganomet. Chem. 1982,225,71. 321 0.Gropen and A. Haaland Acta Chem. Scand. Sect. A 1982,36 435. A. J. Welch vinyl complex (135) are generated. Full details of the spectra of these species and of the results of their photoirradiations have now been irradiation of (134) affords a possible bis(ethene) complex whilst irradiation of (135) induces cis-trans isomerization. 3 Gallium The intermetallic compound KGa is one of several species known in the K-Ga system and a single crystal diffraction has shown that in KGa there exist triangulated dodecahedra1 Ga clusters linked into an infinite 3-D lattice by two exopolyhedral Ga atoms.Structural ~t~die~~~~,~~~ of two phases of Na,Gal have revealed the presence of Ga12 icosahedra and open Gals clusters. Ga12 icosahedra are linked both directly and via non-cluster gallium atoms in Na22Ga39.326 The kinetics and equilibria of the reactions between the Ga3' ion and a set of substituted salicylic acids have been in~estigated,~~' and evidence is presented for an associative mode of activation (SN2,).Calorimetric reveal that the formation of the azide GaN32+ (from GaIII perchlorate and NaN3) is much more exothermic than analogous formation of I~IN,~+. In a study whose aim is to assess the feasibility of gallium removal from the protein transferrin Raymond et af.have investigated the solution equilibria of the reactions of Gal1* (and In"') with two sulphated hexadentate and one sulphonated bidentate catechoylamide sequestering ligands at varying pH's and conclude that the hexadenate ligands are at least 1000-times more effective than is transferrin at binding gallium.329 Such studies are very important in developing the use of gallium-67 and indium-1 11 radionu-clides as tumour-imaging reagents. TlGaF6 and ThF6 are isostructural with VF in the solid state and each therefore possesses a statistical distribution of M"' metal ions.33o BallGa4F34 a member of the BaF2-GaF system represents an anion-excess fluorite-related superstruc- t~re.~~~ It is well established that the Ga2X62- ion (X = halide) has an ethane-like structure with a Ga-Ga bond.Nuclear quadrupole resonance (n.q.r.) spectra (35Cl 81 Br and 69Ga) for L2Ga2X6 (L = Me,N or Et4N; X = C1 or Br) are 322 P. H. Kasai I. Am. Chem. SOC.,1982,104 1165. 323 C. Belin and R. G. Ling C.R. Acad. Sci.,Series ZZ 1982 294 1083. 324 U. Frank-Cordier G. Cordier and H. Schafer Z. Naturforsch. Teil B 1982,37 119. 325 U. Frank-Cordier G. Cordier and H. Schafer Z. Nuturforsch. Ted B 1982,37 127. 326 R. G. Ling and C. Belin Acta Crystallogr. Sect. B 1982,38 1101. 32' R. Corigli F. Secco and M. Venturini Znorg. Chem. 1982,21 2992. 328 E. Avsar Acta Chem. Scand. Sect. A 1982.36 627. 329 V. L. Pecoraro G. B. Wong and K. N. Raymond Inorg. Chem. 1982,21,2209. 330 R. Losch Ch. Hebecker and Z. Ranft Z. Anorg.Allg. Chem. 1982,491 199. 331 R. Awadallah J.-P. Laval and B. Frit C.R. Acad. Sci.,Series II 1982 295 725. 332 T. Okuda N. Yoshida M. Hiura H. Ishihara K. Yamada and H. Negita I.Mol. Struct. 1982,96 169. B Al Ga In T1 79 and the n.q.r. frequencies used to calculate the electron distributions on metal and halide atoms in the anions The Ga2162- ion exists (as its Ga' salt) in the metal-rich gallium iodide 'Ga213' and a crystallographic study of it has yielded a Ga-Ga distance of 2.387(5) A identical to that in the chloride. The same paper3, reports a structural analysis of 'GaI,' i.e. the expected Ga'[GaI,]:. An important aspect of both studies is the influence upon the crystal structures of the non-bonding electron-pair of the Ga' ions. Ga-Ga bonds also occur in the covalent dimeric species Ga2Br4( 1,4-dio~ane)~ Ga-Ga 2.395(6) and Ga2Br4py2 Ga-Ga 2.421(3) A.335The former compound is similar to its chloride analogue and thus represents a second example of the family Ga2X,.2L (L = potentially bidentate ligand) which are metal-metal bonded covalent species in which L acts in only unidentate fashion (as opposed to the mixed-oxidation state alternative formulation [GaL,]'[GaX,]->.The pyridine compound represents the first member of the potentially large class Ga,X,L' (L' = monodentate ligand) whose feasibility was suggested by the existence of the dioxane species. In crystals of Cu(GaCl,) the central Cu" atom has a square planar geometry being linked to each Ga atom by a pair of chloride bridges and Raman spectroscopy indicated that a similar structure is retained in the vapour The dimer [(thf)(C2H3)GaFe(CO)4]2 has a similar structure to that of the isoelectronic species [(2,2'-bipy)ZnFe(CO)4]2 and [Et,GeFe(CO),], uiz a centro- symmetric four-membered GaFeGaFk ring core with pendant vinyl and thf (on Ga) and CO (on Fe) ligands.The average Ga-Fe bond distance is 2.516(3)A.337 Ga-Mn bonded species [C14-,Ga{Mn(CO)5}n]- (n = 1,2 or 3) are afforded338 by reaction of GaC1 with Na[Mn(CO)5]. InCl gives analogous products but In(C3H7C02) reacts with Na[Mn(CO),L] [L = CO or PPh3) to yield [(C3H7C02)2 InMn(CO),L] in which the two carboxylato ligands chelate to give an indium co-ordination number of five. In the series [Me,-,MCl,]- (M = Ga or In) both the M-Cl and M-C stretching force constants determined from normal co-ordinate analysis of vibrational frequencies increase substantially and monatomically from n = 0 to n = 4 results that have been discussed in terms of a combination of inductive and resonance In the adduct Me,NGaCl the Ga-N stretching force constant has a calculated value34o of 2.50 mdyn A-' larger than that in Me3NGaH3 (2.43) and in Me,NGaMe$ (1.61) (in which the gallium centre is a progressively weaker acid) and much larger than that in H,NGaH3 (1.08)341(where the gallium is a weaker acid and the amine a weaker base).The Ga-P bond in Me,PGaCl3 has a stretching force constant of 2.01 mdyn kl, and the lower value of the metal-ligand force 333 G. Gerlach W. Honle and A. Simon 2.Anorg.Allg. Chem. 1982 486 7. 334 R. W. H. Small and I. J. Worrall Acta Crystallogr. Sect. B 1982 38 250. 335 R. W. H. Small and I. J. Worrall Acta Crystallogr. Sect. B 1982 38 86. 336 C. Verries-Peylhard C.R. Acad. Sci. Series ZZ 1982,295 171. 337 J. C. Vanderhooft R. D. Ernst F. W. Cagle jun. R. J. Neustadt and T. H. Cymbaluk Znorg. Chem. 1982,21 1876. H.-J. Haupt F. Neumann and B. Schwab 2.Anorg. Allg. Chem. 1982,485 234. 339 A. Haaland and J. Weidlein Acta Chem. Scand. Sect. A 1982.36 805. 340 J. R. Durig and K. K. Chatterjee J. Mol. Strwct. 1982,95 105. 34' J. R. Durig C. B. Bradley and J. D. Odom Znorg. Chem. 1982 21 1466. A. J. We,& constant here compared to that in the trimethylamine analogue is quite consistent with the reduced base-strength of PMe us.NMe3.342 Urotropine C6H12N4 has four potential base sites. However in reaction with Me,M (M = Al Ga In or T1) in various (1 1 to 1:4 respectively) molar ratios stable 1 1 1:2 and 1:3 but no 1:4 adducts are afforded.343 Vibrational spectroscopy clearly shows the changes in symmetry of the C6N4 skeleton in the series of adducts (1:1 C3u;1:2 CZu;1:3 C,,),and structural conformation of the 1:1 (136) and 1:2 (137) adducts for M = Ga is afforded by crystallographic studies. c2' c7 (137) (Reproduced by permission from J. Organomet. Chem. 1982,235,253) 342 J. R. Durig and K. K. Chatterjee J. Mol. Struct. 1982 81 167. 343 H. Krause K. Sille H.-D. Hausen and J. Weidlein J. Organomel. Chem. 1982 235 253. B Al Ga In T1 RGaC12 (R = Me or Bu) reacts with two equivalents of (Me3S&NH to afford [R(C1)GaN(H)SiMe312,(138).Five geometrical isomers of (138) are feasible but the reaction products have only narrow melting point ranges suggesting that only one is present in the solid Single-crystal XRD study of the methyl analogue (H)(Me3Si)N-Ga(C1) (R) II (R)(CI)Ga-N(SiMe3) (H) (138) of (138)shows this to have the trans-trans information (Cisymmetry) and compara- tive i.r. spectra suggest that this is also the stereochemistry of the butyl compound. Although two equivalents of (Me3Si)NH were used no evidence is found for the possible adduct R(C1)GaN (H)SiMe3.N (H)SiMe3. Reaction of Me3M (M = Ga or In) with LY -tropolone yields dimethylmetal tropol- onates Me2M(C5H702) monomeric in solution but dimeric at least for M = Ga in the solid In the crystallographically determined structure (139) the intramolecular Ga-0 bonds 1.974(5) and 2.025(3)A,are supplemented by a weaker intermolecular contact Ga-0- l’ 2.463(3)A.Rather surprisingly the shorter intramolecular Ga-0 bond is to 0-1. ,*z\ F:. c,,&I?a\\, c2-\ ‘\ 1 c‘-I /Q.-C,* 7l-O’. \ /cs “\ q\ C,-C I 8;O:C c71 (139) (Reproduced by permission from J. Organomet. Chem. 1982,232 99) The accepted trend of increasing bond strength In-0 < Ga-0 < A1-0 is consistent with observed trends (19F n.m.r. spectroscopy) in coalescence tem- peratures and activation energies for cis-trans rearrangements via bond rupture in stereochemically non-rigid tris(p -diketonates) with fluoro-s~bstituents.~~~ The structure of @-Ga203 consists of edge-sharing Ga06 octahedra and vertex- sharing GaO tetrahedra.Assuming a mean Ga-0 distance of 1.83 A analysis of the vibrational spectra of p -Ga203 between 4 and 1000K has allowed calculation347 344 W. R.Nutt R.E. Stimson M. F. Leopold and B. H. Rubin Znorg. Chem. 1982 21 1909. 345 I. Waller T. Halder W. Schwarz and J. Weidlein J. Organomet. Chem. 1982 232 99. 346 D. T. Haworth J. W. Beery and M. Das Polyhedron 1982 1 9. 347 D. Dohy and G. Lucazeau J. Mol. Struct. 1982. 79 419. A. J. Welch of stretchingforce-constantsof 0.6-1.3 mdyn k'and 1.65-2.2 mdyn A-' respec-tively for these two types of Ga-0 bonds. Ga203 reacts with PbO at ca. 700 "C to afford Pb9GaEOzl shown crystallographically348 to contain vertex sharing GaO tetrahedra the mean Ga-0 distance in which is 1.835A.Adamantane-like thio- and seleno-anions Ga4Sl;- In4SlO8- and In4SeloE- have been isolated by nucleophilic degradation of M2X3 by Mf2X(M' = alkali metal) in aqueous As potassium salts (with 16 molecules of water of crystalliz- ation) all are isotypic and the anions are represented by the Ga4Slo8- ion (140). Analysis of vibrational spectroscopic data for the sulphides yields stretching force-constants below the accepted values for M-S single bonds. (140) (Reproduced by permission from horg. Chim. Actu 1982,65 L101) Gas tetrahedra occur as part of extended lattices in LaGaS3,350 Fe2Ga2S5,351 and (Mo),Ga2S5 (M = Nd,352 Ce353 and La353) whilst in La3,,,Ga6O2SI2 there exist sheets of both Gas4 and GaOS3 tetrahedra.354 Throughout this series of mixed sulphides the Ga-S bond lengths span the fairly narrow range 2.191(8)-2.358(6)A.4 Indium An investigation of the kinetics of the reaction between the In3' ion and the indicator ferron 8-hydroxy-7-iodoquinolinium-5-sulphonate, offers evidence3s5 348 K.-B. Plotz and Hk. Muller-Buschbaum Z. Anorg. AIIg. Chem. 1982 484 153. 349 B. Krebs D. Voelker and K.-0. Stiller Znorg. Chim. Acta 1982,65 L101. 350 M. Julien-Pouzol S. Jaulmes and C. Dagron Actu Crystullogr. Sect. B 1982.38. 1566. 351 L. Dogguy-Smiri and N. Huy-Dung Actu Crystallogr. Sect. B 1982 38 372. 352 J. Dugu6 and M. Guittard Actu Crystallogr. Sect. B 1982 38 2368.353 S. Jaulmes E. Godleweski M. Palazzi and J. Etienne Acta Crystullogr. Sect. B 1982 38 1707. 354 A. Mauzurier M. Guittard and S. Jaulmes Acra Crystallogr. Sect. B 1982 38 379. 355 B. Perlmutter-Hayman F. Secco and M. Venturini J. Chem. Soc. Dalton Trans. 1982 1945. B Al Ga In TI 83 that an associative Eigen mechanism is appropriate. In the hydrolysis of In3' numerical analysis356 supports the species In(OH)" In(OH),' and In4(OH)48' as 'best models' whilst in a separate In2(0H):' and are con- sidered important. InCp has been studied theoretically by CNDO calculations and the calculated MO energies compared with the experimental p.e. In this the lowest ionization potential is assigned to removal of an electron from the lone pair on In in contrast to previous interpretations.The bonding in InCp is discussed in terms of essentially covalent interaction between indium valence orbitals and Cp T-orbitals. InCp has been a suitable point for entry into indium(1) chemistry because of its generally greater solubility than indium(1) halides InX. However the best route to InCp starts with InX as described by Tuck et al. last year. Clearly a direct entry into In' chemistry from InX would be desirable and that has now been gained via the by the same authors that halides InX are soluble in either toluene or CH2C12 containing neutral organic bases at temperatures below 0 "C. Inter alia the InX solutions are useful precursors for the adducts In2X4.2L (L = tmen PR3 etc.).An alternative route to adducts of this type is via reaction of InX2 with L and this method has been exploited by Tuck and co-~orkers~~~ (who describe the preparation of In2X4.2L,L = tmen or PEt3; and 111~&(tmen)~.C~H~ X = Br or I) and by Sinclair and W0rra11~~~ (InzX4-2L X = C1 Br or I and L = 1,4-dioxane tetrahydropyran thf or tetrahydrothibphene; X = Br or I and L = dmso and In2X4-4L X = C1 Br or I and L = piperidine piperazine or morpholine; X = Br or I and L = py or dmso).Both groups have analysed solid-state vibrational spectra of these species in terms of the metal-metal bonded species (141) or (142) v~,,-~, occurring at ca. 170-175cm-' (X = Cl) ca. 140-145cm-1 (X = Br) and ca. L \ xx IIl-Ii' ;A \L xx In2X4.2L In2X4.4L (141) (142) 105-115 cm-' (X = I).Unfortunately it has not yet proven possible to grow crystals of either species suitable for X-ray diffraction. Whilst formally In" species,36o the total valency of the metal atoms in these dimers is obviously three. Suitable crystals have been obtained of the series of [NBu4]' salts of InC14- InBr4- InBrC13- and InBr3C1- and all have been studied by XRD.362 All are isomorphous and str,uctural study affords two crystallographically independent In-X distances per structure. For the tetrahalides these are 2.345(3) and 2.355(3)A and 2.479(2) and 2.479(3) A respectively. The mixed species are 356 P. L. Brown J. Ellis and R. N. Sylva J. Chem. SOC.,Dalton Trans. 1982 1911. 357 G. Biedermann and D. Ferri AcfaChem. Scand. Secf.A. 1982 36 611. 358 C.S. Lin and D. G. Tuck Can.J. Chem. 1982,60,699. 359 C. Peppe D. G. Tuck and L. Victoriano J. Chem. SOC.,Dalton Trans. 1982 2165. 360 M. J. Taylor D. G.Tuck and L. Victoriano Can.J. Chem. 1982,60 690. 361 I. Sinclair and I. J. Worrall Can.J. Chem. 1982 60 695. 362 M. A. Khan and D. G.Tuck Acta Crystallogr. Sect. B 1982 38 803. A. J Welch disordered with the odd halide having 25% occupancy of all four co-ordination sites. Not surprisingly measured In-X distances are intermediate between the two previous extremes. BaInClS Ba21nCl7 and Ba31nC1 have been (by differential thermal analysis) in the phase diagram of BaC1,/InC13. Double salts in the KX/InX3/Hz0 systems (X = C1 or Br) at 21°C are K31nC16-Hz0 and Kz[InCl5.HZ0] and K31nBr6- 1.5H20 Kz[InBr,.H20] K[InBr4(H20)2] and K31n2Br9 as identified by Raman spectroscopy and (less reliably) polycrystalline XRD.364 The oxysulphide of indium and lanthanum In6Lal0O6Sl7 has been subjected to a full 3-D crystallo- graphic analysis,365 whilst a study of In3z0N17F34 both X-ray and neutron diffrac- tiop366 reveals a fluorite-related structure.In6WOI has a fluorite ~uperstructure,~~' In centres having a distorted cubic environment of seven nearest-neighbour oxygens with six In-0 distances between 2.07 and 2.28 A and one of 2.77 A an arrange- ment that is similar to that in the bixbyite (LnzO3) structure of Inz03. Reduced In203 has recently been shown to be a superior oxide to reduced Fe203 for the generation of HZ from steam since the indium-based process operates at lower temperatures and has almost quantitative conversion.A number of carriers of In203 in this process have now been best results being obtained for TiOz Zr02 ZnO active carbon. In [H30][In(H20)2(S04)2]-2H20 the bound water atoms are mutually trans -In-OH2 2.134(5) and 2.143(5) A and each SO function links two metal atoms In-OS(O),O 2-104(6) to 2.157(6) A into infinite Double oxides of zinc and indium Zn31nz06 Zn4In2O7 Zn,In208 and Zn7In2Ol0 have been synthesized by calcination of differing ratios of ZnO and In203 and have been characterized by vibrational The double sulphides A121n4S9 and GazIn4S are obtained by chemical vapour transport and their powder XRD data have been In [Inz(dto)5]4- (dto = 1,2-dithio-oxalate) structurally studied as its Ph4As' salt one dto Iigand bridges the two metal-centres in a trans conformation (143).The geometry at In is distorted octahedral with In-S to the bridging ligand substantially longer than that to the terminal dto functions 2.638(4) us. 2.544(3)-2.560(3) A 363 R. Blachnik and J. E. Alberts 2.Anorg. Alig. Chem. 1982 490 235. 364 J. P. Wignacourt G. Mairesse P. Barbier A. Lorriaux-Rubbens and F. Wallart Can. J. Chem. 1982,60 1747. 365 L. Gastaldi D. Carre and M. P. Pardo Acta Crystallogr. Sect. B 1982 38 2365. 366 N. Abriat J.-P. Laval B. Frit and G. Roult Acta Crystallogr. Sect. B 1982 38 1088. 367 D. Michel and A. Khan Acta Crystallogr. Sect. B 1982 38 1437. K. Otsuka S. Shibuya and A. Morikawa Chem. Lett. 1982,987. 369 R.Caminiti G. Marongiu and G. Paschina Cryst. Struct. Commun. 1982 11 955. 370 N. V. Filatkina N. V. Porotnikov and K. I. Petrov Zh. Neorg. Khim. 1982 27 1664. 37' M. Schulte-Kellinghaus and V. Kramer 2.Naturforsch. Ted B,1982 37 390. 85 B Al Ga In Ti re~pectively.~~’ A metal geometry that is nearly midway along the trigonal- bipyramidai (tbp) to square-pyramidal (sp) Berry co-ordinate is observed in [In{S2C2(CN)2}C1]2’(144),with S-1 and S-1’approximating to quasi-axial ligand~.,~~ 2c \ CN The compounds Ar21nCl and ArMe21n {Ar = 2-Me2NCH(Z)C6H4;Z = H or (S)-Me} could contain either 3- 4- or 5-co-ordinate indium and 3- or 4-co-ordinate indium respectively as Ar is a potential mono- or bi-dentate ligand. ‘H and I3C n.m.r. spectroscopic study indicates its bidentate nature in both but that in pyridine solution the intramolecular In-N bond of ArMe21n is weakened and ultimately cleaved via the scheme outlined in (145) wherein the py ligand becomes co-ordinated.Three pyridine ligands are bound to Inr*’ in a meridional arrangement in InBr3py3.py as established by structural Reaction of InC13 with hmpa {hmpa = hexamethylphorarnide O=P(NMe2),} the adduct InC13(hmpa)z (146),which has a trans tbp geometry whereas In(btsa) {btsa = bis(trirnethylsilyl)amide,N(SiMe),} reacts with O=PMe3 to afford the presumably pseudo-tetrahedral In(bt~a),(OPMe,),~’~ both reactions simply demonstrating the Lewis acidity of InX species. Research has continued towards improved synthetic to InP an important photocathodic material whose surface characteristics are critical to its performance 372 L.Golic N. Bulc and W. Dietzsch Inorg. Chern. 1982 21 3560. 373 R. 0.Day and R. R. Holmes Inorg. Chem. 1982,21,2379. J. T. B. H. Jastrzebski G. van Koten D. G. Tuck H. A. Meinema and J. G. Noltes Otganometallics 1982 1 1492. 375 R. W. H. Small and I. J. Worrall Acta Crystaflogr.,Sect. B 1982 38 932. 37b S. P. Sinha T. T. Pakkenen T. A. Pakkenen and L. Niinisto Polyhedron 1982 1 355. 377 D. C. Bradley and Y. C. Gao Polyhedron 1982 1 307. 378 A. F. Witt Gou. Rep. Announce. Index (US.),1982,82 1452. A. J. Welch Y c** N1 c3 1 c4 (146) (Reproducedby permission from Polyhedron 1982,1 355) in this respect. Spectroscopic ellipsometry and low-energy (He) ion scattering spectroscopy that the 11 1(A) (indium) face of p-InP used as photocathode in solar cells consists of a hydrated Jn203layer (48,thick) below which is a mixed intermediate layer (ca.10 8,)before pure InP. The structures of InMe and TlMe3 in the vapour phase have been redetermined by electron diffra~tion.~~' In the refinements overall C3molecular symmetry are assumed and In-C andT1-C bond lengths of 2.161(3) and 2.206(3) A respectively are detkrmined. The former is in much closer agreement with that obtained in the gas phase for (the dimeric) dimethyl(propyny1)indium and with many In-CH3 distances determined by XRD than was the previously established value of 2.093(6)8, and thus the new length probably represents the better measurement.[LiI2[(PhC),] reacts with InC13py3 and with [Ph4As][InC14] to afford respec- tively (147),and (148),the first examples of unsaturated C41n heterocycles charac- terized by microanalyses and 'H n.m.r. ~pe~tr~~~~py.~~' Evidence for the spiro anion (148) is reinforced by 13C n.m.r. spectroscopy and by its reaction with maleic anhydride. 5 Thallium Reaction of the alloy of composition KTlSn with ethylenediamine (en) contain- ing a stoicheiometric amount of (2,2,2-crypt) affords [222-crypt-K]3+[TlSn9]o.53-[TlSng]o.53-en, structurally identified by X-ray crystallography. The 379 H. J. Lewerenz D. E. Aspnes B. Miller D. L. Malm and A. Heller J. Am. Chem. SOC. 1982 104 3325. 380 T. Fjeldberg A. Haaland R. Seip Q. Shen and J. Weidlein Actu Chem.Scand. Sect. A 1982 36 495. 38' C. Peppe and D. G. Tuck Polyhedron 1982,1,549. B Al Ga,In,TI Ph Ph Ph Ph Ph anion structures are shown in (149) and (150) and geometrically are a bicapped square antiprism and a tricapped trigonal prism respectively. Evidence for the anionic charges derives from (i) the lack of an e.s.r. signal that would be expected if for example one anion were -4 the other -2 and (ii) the fact that -3 charges for both are consistent with the PSEP count for closo-clusters. In both species the heteroatom occupies a vertex of lowest possible connectivity and this is discussed (149) (Reproduced by permission from J. Am. Chem. SOC.,1982,104,2804) Large values of the thallium shielding anisotropy (from measurement of the solid-state *03Tland *''TI n.m.r.spectra) in the ionic TIN03suggest the potential for even larger values in covalent compounds of 382 R. C. Burnsand J. D. Corbett J. Am. Chem. SOC.,1982,104,2804. 383 K.R.Metz and J. F.Hinton I. Am. Chem. SOC.,1982,104,6206. A. J. Welch RbTlBr4.H20 NH4TlBr4-2H20 and (at -50 "C)KTlBr4.2H20 have all been subjected to single-crystal XRD study yielding Tl-Br distances in the anionic tetrahedra of 2.567(3) 2.53 1(9) and 2.549( 11)A re~pectively.~'~ In solid "Bud]- [TlI,] the Tl-I bond lengths lie between 2.723(4) and 2.840(5) A whereas a value of 2.771(3) A is determined from X-ray diffraction of a concentrated solution of the tetrapentylammonium Comparisons are made between the M-X dist-ances in various d" tetrahalides and vibrational spectra of the [NBu,]' salt are also reported.A later paper386 reports solution diffraction studies of the anions TlC14- and TlC1:- (tetrahedral Tl-Cl 2.43(1)A octahedral Tl-Cl 2.59(1)A respectively) and a third387 extends the study to solutions of the hydrated species [Tl(OH2)6]3+,T1-0 2.235(5)A truns-[TlBr2(0H)4]+ Tl-Br 2.481(2)A truns-[T1Br,(OH2),] tbp Tl-Br 2.512(2)A and T1Br4- Tl-Br 2.564(2)A. Two low-valent atoms TI' and Snl*have for the first time been incorporated into a single cage. Reaction of T1-N(Bu')-Si(Me),-O(Bu') (151) with Sn-N(Bu')-Si(Me),-N(Bu') in Bu'OH affords3" the trigonal bipyramidal molecule (152). Although no reference is made to measurement of the dipole moment of (152) it is likely that the molecule is not substantially polar presumably a consequence of the lone pairs of electrons on each metal centre.The analogue of (151) in which But is replaced by Me has been prepared and its chemistry explored by the same group.389 (152) (Reproduced by permission from Angew. Chem. Int. Ed. En& 1982 21,858) A re-e~amination~~'of the mechanism of the reaction between RTl(OAc)2 (OAc = acetate) and P(OMe)3 has suggested initial formation of a 1:1 adduct RTI(OAC)~-P(OM~) rather than disproportionation of the diacetate 384 H. W. Rotter and G. Thiele 2.Nuturforsch. Teil B 1982 37 995. 385 J. Glaser P. L. Goggin M. Sandstrom and V. Lutsko Acta Chem. Scund. Sect. A 1982,36 55. 386 J. Glaser Acta Chem. Scand. Sect. A 1982 36,451. 387 J. Glaser and G.Johansson Acta Chem. Scand. Sect. A 1982,36 125. 388 M. Veith and R. Rosler Angew. Chem. Int. Ed. Engl. 1982 21 858. 389 M. Veith and R. Rosler J. Organomet. Chem. 1982,229 131. 390 H. Kurosawa and M. Sato Organometallics 1982 1,440. B Al Ga In,TI into R,TlOAc and Tl(OAc),. Crystallographic of Tl(OAc),.H20 reveals a simple relationship between its structure and that of the anhydrous compound. Whilst thallium(rI1) carboxylates have been successfully used to prepare organo- platinum compounds that are otherwise intractable no evidence for stable heterodinuclear complexes (containing a Pt-TI bond) has been in marked contrast to the results of similar studies using (the isoelectronic) mcrcury(I1) carboxy- lates. A crystal structure determinati~n~~’ of 4-MeC6H4-T1(S2CNEt,) (153) reveals a distorted square-pyramidal geometry (p-tolyl ligand axial) and affords TI-C and T1-S distances of 2.15(1) and 2.569(4) (to S-1) and 2.762(4)A (to S-2) respectively.P“ c7 c3 C6 c4 lC36 (Reproduced by permission from 2.Anorg. Aflg. Chern. 1982,485 217) In the linear [Me-T1-Me]’ cation ‘threaded’ through the crown ethers (dibenzo- 18-cr0wn-6)~~~ and (dicyclohexano-18-crown-6,two isomers)395 TI-C distances span 2.097(9) to 2.180(7)A. One of the main thrusts of this work is restriction of the effects of solvent and/or anion on the cation in order to simplify measurement of n.m.r. parameters. 391 R. Faggiani and I. D. Brown Acta Crystallogr. Sect. B 1982 38 2473. 392 A. F. M. J. van der Ploeg G.van Koten and K.Vrieze Inorg. Chim. Acra 1982 58 35. 393 Ch. Burschka 2. Anorg. Allg. Chem. 1982,485 217. 394 K. Henrick R. W. Matthews B. L. Podejma and P. A. Tasker J. Chem. SOC. Chem. Commun. 1982,118. 395 D. L. Hughes and M. L. Truter J. Chem. Soc. Chem. Commun. 1982,727.