Direct syntheses and complete characterization of halide-free tetrakis(dialkylamino)silanes

Efficient syntheses of tetrakis(dimethylamino)silane, tetrakis(methylethylamino)silane, and tetrakis(diethylamino)silane yield analytically pure compounds as halide-free species whose volatility systematically decreases with the addition of each ethyl group. Tetrakis(dialkylamino)silanes of the general formula Si(NRR′) 4 (R = R′ CH 3 , CH 2 CH 3 , or R ≠ R′ = CH 3 and CH 2 CH 3 ) were prepared as halide-free, analytically pure compounds whose volatility scales with alkyl group size. The successful syntheses relied on the heavier silicon halides, SiBr 4 , and SiI 4 . In the case of SiBr 4 incomplete amination with amines bulkier than dimethylamine ultimately led exclusively to BrSi(NR 2 ) 3 , whereas SiI 4 starting material afforded only homoleptic Si(NR 2 ) 4 whose complete characterization is presented. The tetrakis(dialkylamino)silanes failed to react with alcohols, even at elevated temperatures, and only slowly hydrolyze.