Poly(Alkyl/Arylphosphazene) Chains and Rings Via Condensation Reactions of Si-N-P Precursors

The thermal decomposition of P-functional N-silylphosphoranimines, Me 3 SiN = P(X)R 2 , is an effective synthetic route to cyclic and polymeric phosphazenes that are fully substituted with P-alkyl/aryl side groups. Results of some recent studies of this condensation reaction and its products are reported, including: (1) the synthesis of a variety of new precursors with P-alkoxy and P-aryloxy substituents, (2) the effect of the leaving group (X) on the polymerization/cyclization process, and (3) the synthesis of a series of dialkyl cyclic phosphazenes, [R 2 PN] n (e.g., n = 3, 4, 5; R = Et, n-Pr, n-Bu, n-Hx).