Thermally-induced transformations of gallium and indium alkyl phosphido complexes: Dealkylsilylation routes to MP (M=Ga, In)

The dehalosilylation reaction of (Bu2GaCl)-Bu-n with 1 equiv of P(SiMe3)(3) provided [(Bu2GaP)-Bu-n(SiMe3)(2)](2) (1) in good yield. A similar reaction between (BuGaCl2)-Bu-n and P(SiMe3)(3) gave [Bu-n(Cl)GaP(SiMe3)(2)](2) (2). Compound 1 was characterized by X-ray crystallography and possesses an approximately square planar Ga2P2 molecular core. Both the P and the Ga centers are in distorted tetrahedral environments. Thermolysis of 1, at 400 degrees C, produced GaP and BuSiMe3 and no other crystalline products, as confirmed by thermogravimetric and spectroscopic analysis. The indium analogue of 1, [(Bu-n)(2)InP(SiMe3)(2)](2) (3), was prepared from the reaction of (Bu-n)(2)InCl with P(SiMe3)(3). The thermolysis of 3 at 400 degrees C under nitrogen produced butene, butane, and butyltrimethylsilane as organic products and a dark grey solid. Powder X-ray diffraction of this solid revealed it to consist of InP add metallic indium. Combination of In(Bu-n)(3) with P(SiMe3)(3) produced the monomeric adduct (Bu-n)(3)In . P(SiMe3)(3) (4). The thermal reactivity of complex 4 was investigated at various temperatures. At 130 degrees C in a sealed tube, the products of thermolysis are [(Bu-n)(2)InP(SiMe3)(2)](2) (3) and In-0. While complex 1 is a potential precursor to GaP via a dealkylsilylation mechanism, the indium analogue 3 and the adduct 4 appear to have a more facile beta-hydrogen elimination pathway which makes them less suitable for the production of pure InP.