Malcolm G. H. Wallbridge

Synthesis of di-, tri- and penta-nuclear titanium(IV) species from reactions of titanium(IV) alkoxides with 2,2′-biphenol (H2L1) and 1,1′-binaphthol (H2L2); crystal structures of [Ti3(μ2-OPri)2(OPri)8L1], [Ti3(OPri)6L13], [Ti5(μ3-O)2(μ2-OR)2(OR)6L14](R = OPri, OBun) and [Ti2(OPri)4L22]

Reaction of titanium(IV) alkoxides [Ti(OR)4] (R = OPri, OBun) with 2,2′-biphenol [C12H8(OH)2, H2L1] affords two trinuclear species [Ti3(OPri)10L1] and [Ti3(OPri)6L13] each possessing an open-chain V-shaped arrangement of three titanium atoms with the former having both bridging alkoxide and biphenylate groups and the latter having only biphenylate as bridging groups. Variations in reaction conditions yield the pentanuclear species [Ti5(μ3-O)2(OR)8L14] (R = OPri, OBun) which have two central bridging oxygen atoms in the Ti5 framework and bridging alkoxide and biphenylate groups. In contrast 1,1′-binaphthol [C24H12(OH)2, H2L2] yields the dinuclear [Ti2(OPri)4L22] where only the binaphthylate ligands act as bridging groups. Some of the compounds show catalytic activity in esterification reactions.

Synthesis and properties of some gallium amidine complexes [GaXyL3–y][X = Me, Et or Cl; L = RNCR′NR (R, R′= H, alkyl or aryl); y= 0–2]. Crystal structures of [GaMe2(PhNCPhNPh)] and [GaMe(PhNCPhNPh)2]

The amidinato compounds [GaMe2L][L = RNCR′NR (R,R′= H, alkyl or aryl)], [GaMe(PhNCPhNPh)2], [GaEt(PhNCMeNPh)2] and [Ga(PhNCRNPh)3](R = Me or Ph) have been isolated from the reaction of the appropriate gallium trialkyl with 1, 2 and 3 mol of amidine RNCR′N(H)R, respectively. The chloro derivatives [GaCl3{RNCR′N(H)R}](R = Ph or p-ClC6H4; R′= Me) and [GaCl2(p-ClC6H4NCMeNC6H4Cl-p)] have also been prepared. The compounds have been fully characterised, and mass spectrometric data indicate that the volatile dimethylgallium derivatives exist as either monomers or dimers in the gas phase. X-Ray crystallographic studies on [GaMe2(PhNCPhNPh)] and [GaMe(PhNCPhNPh)2] revealed monomeric structures and the presence of chelating amidinate ligands, with distorted tetrahedral and trigonal-bipyramidal co-ordination respectively at the metal centres. Cleavage of the Ga–Me bond occurs on photolysis in the presence of a spin-trapping agent, and thermal decomposition of the solids leads to the formation of gallium nitride.

Preparation and characterisation of novel organoindium derivatives; X-ray crystal structure of dimethyl(salicylaldehyde)indium

Abstract The reaction of trimethylindium with one equivalent of salicylaldehyde, 2-car☐ybenzaldehyde, 2-pyrrolidinone or N, N′-diphenylacetamidine results in the formation of the corresponding dimethylindium derivatives in good yields. The product obtained from the reaction with salicylaldehyde has been shown by a single crystal X-ray diffraction study to consist of centrosymmetric dimers with five-coordinate indium atoms, In-C 2.122(5), In-O(CHO) 2.34(4), In-O(OH) 2.188(3) and 2.383(3)A˚. The reactions between triethylindium and phenylacetylene and ethanolamine are described.

An octameric titanium oxo metallacycle with host–guest interactions

Treatment of TiCl4 with carboxylic acids RCO2H (R = C6F5, CH2C6F5, CH2OC6F5) yields a series of titanium oxo compounds; the X-ray molecular structure of [TiO(O2CC6F5)2] reveals an octameric unit and a unique 16-membered Ti8O8 ring, with two toluene molecules encapsulated above and below the ring in the molecular cavity.

Carbaborane derivatives of the late- and post-transition elements. Part 2. Dicarbaundecaboranyl compounds of copper(I), gold(I), and mercury(II); the crystal and molecular structure of 3-triphenylphosphine-3-mercura-1,2-dicarbadodecaborane(II), a pseudo-σ-bonded metallacarbaborane

The novel d10 metallacarbaboranes B9C21,2[Hg(PPh3)]3H11(1), [AsPh4][B9C21,2(HgMe)3H11], B9C21,2[Au(PPh3)]3(NC5H5)4H10, B9C21,2[Cu(PPh3)]3(NC5H5)4H10, and [3.3′-{HgB9C21,2(NC5H5)4H10}2] have been prepared by reactions of [{HgCl2(PPh3)}2] with Tl[B9C21,2Tl3H11], [HgMe(O2CMe)] with aqueous K[B9C2H12]–K[OH], and Na[B9C27,8(NC5H5)9H10] with [AuCl(PPh3)], [{CuCl(PPh3)}4], and HgCl2 respectively. The molecular structure of compound(1), as the 0.5-dioxan solvate, has been determined at –60 °C, and shows the mercury atom to be co-ordinated almost linearly by PPh3 and the unique boron atom of the C2B3 face, implying a direct mercury–boron σ bond (Hg–B 2.20, Hg–P 2.39 A, P–Hg–B 172°). The crystals are triclinic, space group P with cell dimensions a= 10.913 5(17), b= 11.188 3(19), c= 12.007 1(18)A, α= 83.50(1), β= 86.98(1), γ= 61.55(1)°, and Z= 2, and the structure has been refined to R= 0.037 for 2 447 independent observed reflections.

Synthesis and chemical properties of dicyclopentadienylzirconium bis(diphenylarsenide) and bis(diphenylantimonide), [(η-C5H5)2Zr(EPh2)2] (E = As OR Sb)

Abstract Treatment of Cp 2 ZrCl 2 (Cp = η-C 5 H 5 ) with LiEPh 2 (E = As or Sb) affords the corresponding pentelide complexes Cp 2 Zr(EPh 2 ) 2 . In the particular case of the Cp 2 TiCl 2 /LiAsPh 2 system there is evidence for reduction to Cp 2 TiAsPh 2 . The spectral and elemental characterisation and thermal degradation properties (from mass spectrometric studies) of these new compounds are discussed. The reactions of the metal(IV) pentelide complexes with protic reagents (including water) and halogen-containing compounds have been investigated, and compared with similar reactions for the phosphide-derivative Cp 2 Zr(PPh 2 ) 2 ; the majority are metathetical reactions involving halide /EPh 2 exchange.

The high-yield preparation of arachno-thiaboranes 4-SB8H12 and 4-SB8H−11

Abstract The oxidative degradation of arachno -6-SB 9 H − 12 , using formaldehyde as an oxidizing agent, affords arachno -4-SB 8 H 12 in practically quantitative yield; the deprotonation of 4-SB 8 H 12 with NaH produces the new arachno -4-SB 8 H − 11 anion, in quantitative yield.

Preparation and properties of some chlorotitanium carboxylates. X-ray crystal and molecular structures of [{TiCl3(O2CCMe3)}3] and [Ti2Cl7(O2CR)(RCO2H)] (R=p-ClC6H4 or CH=CHMe)

Reactions of TiCl4 with carboxylic acids yield the trichloro(carboxylate) compounds [TiCl3(O2CR)](R = Ph, p-MeC6H4, o-MeC6H4, 2,4,6-Me3C6H2, CMePh2, CHMe2, Me3C 1, C9H6N, CHCHPh or CHCHMe). The air-sensitive pivalate 1 is trimeric from crystal-structure analysis, with all carboxylates symmetrically bridging between two Ti atoms, and with one double and one triple bridging Cl {triclinic, space group P, R= 0.059 for 3718 observed [I/σ(I) > 3.0] reflections}. Spectroscopic data suggest similar carboxylate bonding modes in the remaining compounds. Some reactions of the [TiCl3(O2CR)] compounds are described. Under more moderate conditions intermediates of composition [Ti2Cl7(O2CR)(RCO2H)] are obtained. Single-crystal X-ray analyses have been obtained for two such products, 2(R =p-ClC6H4){triclinic, space group P, R= 0.078 for 1727 observed [I/σ(I) > 2.0] reflections} and 3(R = CHCHMe){triclinic space group, P, R= 0.070 for 1219 observed [I/σ(I) > 2.0] reflections}. They show similar structures, with each having a carboxylate anion bridging a bent Ti2Cl6 unit, and the sixth position of the octahedral titanium atom occupied by Cl and the co-ordinated neutral acid molecule.

Characterisation of degradation products in the oxidation of the dodecahydro-7,8-dicarba-nido-undecaborate(1–) ion: a new synthesis of 4,5-dicarba-nido-nonaborane(11)

Degradation of aqueous 1 mol dm–3 K[B9C27,8H12] by aqueous FeCl3(1.25 mol dm–3) yields B8C25,6H12(33%) as previously reported, together with B8C25,6H11(OH)(1.6%), B8C25,6ClH11(0.9%). and B7C24,5H11(4.2%). The yield of B7C24,5H11 may be increased substantially by using lower concentrations of reactants (0.1–0.2 mol dm–3), and this reaction thus provides a simple synthesis of this otherwise highly inaccessible carba-borane. The mass spectrum of B7C24,5H11 has been obtained. The 11B n.m.r. spectrum of B8C25,6ClH11, when compared with spectra of the four isomers of B10ClH13, suggests that substitution has occurred at the 10 position, but the position of substitution of the hydroxy-group in B8C25,6H11(OH) remains uncertain.

N,N′-Unsubstituted amidinato metallacycle complexes of Group 13 metal alkyls: the crystal structure of trimeric [{Me2Al(μ-HNCPhNH)}3]

Abstract The amidinato complexes [Me 2 ML] (L=HNCPhNH, M=Al, Ga, In; L=HNCBu t NH, M=Ga) result from the reaction of the trialkylmetal with an equimolar amount of the amidine. MS data indicate that the complexes exist as dimers or trimers in the gas phase. X-ray crystallographic studies on [{Me 2 Al(μ-HNCPhNH)} 3 ] ( 1 ) reveal a novel trimeric structure in the solid state, with bridging benzamidinato ligands, and a 12-membered metallacycle. Reaction of InMe 3 with two moles of benzamidine yields a cyclic imidoylamidinato derivative with a six-membered [InNCNCN] ring.