RING EXPANSION AND EQUILIBRATION IN ORGANOPHOSPHAZENES AND THE RELATIONSHIP TO POLYMERIZATION

A series of cyclic trimeric phosphazenes that bear both halogen and organic side groups have been found to undergo ring expansion-equilibration reactions at elevated temperatures. Compounds N3P3F5CMe3, N3P3F5Ph, non-gem-N3P3F4(CMe3)2, N3P3F4Ph2, N3P3Cl4Me2, N3P3Cl4Et2, N3P3Cl3Me3, and N3P3Cl3Et3yield cyclic tetramers, pentamers, hexamers, and, in some cases, heptamers, octamers, and nonamers when heated. The cyclic tetramers (NPClMe)4and (NPClEt)4also equilibrate to a range of cyclic species that range from trimer to hexamer. Several of these equilibrations also lead to the formation of high polymers. The results are discussed in terms of possible mechanisms for ring-ring equilibration and polymerization. © 1990, American Chemical Society. All rights reserved.