Synthesis of Poly(dialkylphosphazenes) from N-Silylphosphinimines

Many N-silylphosphinimines Me₃SiN?P(X) RR′ undergo facile thermal decomposition with elimination of substituted silanes Me₃SiX and formation of cyclic or polymeric phosphazenes (RR′PN). The process which is a new, general synthesis of phosphazenes has been used to prepare poly(dimethylphosphazene), (Me₂PN), in nearly quantitative yield from Me₃SiN?P(OCH₂CF₃)Me₂. Convenient synthetic routes to the necessary silicon-nitrogen-phosphorus precursors are described and the results of their decomposition reactions are reported.