Silicon–nitrogen compounds. Part VIII. Base-promoted disproportionation of N-methyl- and N-phenyl-disilazane

Abstract

Liquid N-methyldisilazane, (SiH₃)₂NMe, disproportionates when mixed with ammonia or methylamine at or below room temperature to give silane, hydrogen, and chiefly involatile products. Moderate heating is necessary with pyridine, trimethylamine, or tetradrofuran. Rates of silane evolution lie in the order: NH₃ > NH₂Me C₅H₅N NMe₃ > C₄H₈O. N-Phenyldisilazane reacts similarly, but more slowly, and the order of bases is: NH₃ > NH₂Me PhNH₂∼ C₅H₅N. From the stoicheiometry of the reactions and the properties, including i.r. spectra, of the products, it appears that tertiary amines yield essentially linear oligomers with SiH₃NR end-groups. Primary amines and ammonia induce amine exchange and form cross-linked polmers with NR bridging groups and chiefly NHR end-groups. A mechanism to account for these facts is proposed. Polymer derived from (SiH₃)₂NMe and methylamine slowly reduces gaseous methylamine to ammonia at room temperature.