Gallane complexes

Treatment of GaH3(quin) (quin = quinuclidine) with 1 equivalent of the sterically bulky formamidine as shown in Scheme 40 resulted in formation of a monomeric amido-gallane complex containing a monodentate amidinate ligand. Reaction of this species with a second equivalent of the amidine led to displacement of the quinuclidine ligand and formation of a five-coordinate monohydride complex, which could also be prepared directly by a one-pot reaction of GaHsfquin) with the free amidine in a molar ratio of 1 2 ... 

The l-azabicyclo[2.2.2]octane (quinuclidine) gallane complex is a colorless crystalline solid, highly sensitive to air and moisture. Melting point... 

As mentioned in Section IV.C, the replacement of boron by its heavier congeners aluminium and gallium markedly affects the coordination behavior of the DPE ligands (E = group 13 element) toward AuCl. In particular, the zwitterionic and neutral forms of the diphosphine-gallane complex 103 were shown to coexist and interconvert in solution.27... 

Gallane and its Lewis base complexes react readily with protic acids to eliminate hydrogen. Thus complexes of the type GaH2X(NMe3) and GaHX2(NMe3) (X = Cl, Br) are readily prepared by reaction of HX on the gallane complex at low temperatures. The reactions shown in Scheme T are examples of an elimination-condensation reaction with a secondary amine and the reduction of an imine both reaction types have been observed for alumimun hydrides. 

Unlike boron, the development of heavier Group 13 congener complexes with carbenes has been sluggish. Like boron, however, early examples of carbene complexes with Al, Ga, and In were simple Lewis adducts of the carbene with ER3 species (E = Al, Ga, or In R = alkyl, aryl, halide, or hydride). Recently, Aldridge explored the coordination chemistry of NHC-EHj adducts (104, E = Al or Ga) with [M(CO)4(COD)] (M = Cr, Mo), and was able to prepare the first examples of o-gallane complexes (105, Seheme 5.18). ... 

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