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

Tetrakis(dialkylamino)silanes of the general formula Si(NRR′)4 (R = R′ CH3, CH2CH3, or R ≠ R′ = CH3 and CH2CH3) were prepared as halide-free, analytically pure compounds whose volatility scales with alkyl group size. The successful syntheses relied on the heavier silicon halides, SiBr4, and SiI4. In the case of SiBr4 incomplete amination with amines bulkier than dimethylamine ultimately led exclusively to BrSi(NR2)3, whereas SiI4 starting material afforded only homoleptic Si(NR2)4 whose complete characterization is presented. The tetrakis(dialkylamino)silanes failed to react with alcohols, even at elevated temperatures, and only slowly hydrolyze.