Synthesis and characterization of mixed-substituent N-silylphosphoranimines

The preparation of a large series of new N-silyl-P-alkylphosphoranimines and their (silylamino)phosphine precursors is reported. Oxidative bromination of the P-functional (silylamino)phosphines, (Me3Si)(2)NP(R)X [R = n-Pr, n-Bu, i-Pr, t-Bu; X = Br, OR' (R' = CH2CF3, Ph)], occurred smoothly at 0 degreesC and afforded the desired P-bromophosphoranimines, Me3SiN=P(R)(X)Br. Nucleophilic substitution reactions of the P-dibromo members of this series with LiOR' gave the corresponding P-trifluoroethoxy- and P-phenoxyphosphoranimines, Me3SiN=P(R)(OR')(2) (R' = CH2CF3, Ph). All of these N-silylphosphoranimines, which are potential precursors to new cyclic and/or polymeric phosphazenes, were obtained as thermally stable, distillable liquids and were characterized by NMR (H-1, C-13, and P-31) spectroscopy and elemental analysis.