Tertiary amine and N-heterocyclic carbene coordinated haloalanes--synthesis, structure, and application.

The preparation of several tertiary amine and N-heterocyclic carbene coordinated chloro- and bromoalanes has been studied and routes to their gram-scale synthesis optimized. This provides a catalogue of well-characterized, thermally stable haloalanes for future application. All complexes have been investigated by spectroscopy (IR, NMR) and, where possible, single-crystal X-ray diffraction structure determination.

Hydride-bromide exchange at an NHC-a new route to brominated alanes and gallanes.

The reaction of [MH(3)(Quinuclidine)] (M = Al or Ga) with an air stable dibrominated N-heterocyclic carbene (NHC) affords the hydride-bromide exchange product [MBr(2)H(NHC)].

Bulky triazenide complexes of alumino- and gallohydrides.

The sterically bulky triazenes DitopN(3)(H)pTol, DitopN(3)(H)Mes, DmpN(3)(H)pTol and DmpN(3)(H)Mes, where Ditop = 2,6-di-p-tolylphenyl, Dmp = 2,6-dimesitylphenyl, pTol = p-MeC(6)H(4) and Mes = 2,4,6-Me(3)C(6)H(2), have been prepared. The reactivity of these triazenide precursors with LiAlH(4) and, in the cases of DmpN(3)(H)pTol and DmpN(3)(H)Mes, LiGaH(4), with diethyl ether as the solvent, has been examined. All reactions were undertaken in a 1:1 ratio giving rise to a variety of aluminium and gallium complexes that either incorporate LiH with a metal to triazenide ratio of 1:1 or generate 'LiH-free' aluminohydrides with aluminium to triazenide ratios of 1:1 or 1:2 dependant on triazenide bulk.

The synthesis of a dichloroalane complex and its reaction with an alpha-diimine.

Reaction of an alpha-diimine, {MesN=CH}2 (Mes=2,4,6-trimethylphenyl), with the dichloroalane [AlCl2H(IMes)] (IMes=1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene) affords an N-heterocyclic carbene (NHC) transfer complex [AlCl2{MesNC(=IMes)C(H)NMes}] rather than the expected hydroalumination product.