ABSTRACT
There is a long history of studies of the structure and stability of phosphonitrilic materials dating back to 1834, when Leibig [1] and Rose [2] first observed that phosphorus pentachloride would react with ammonia to yield a stable, white, crystalline solid. Continued work on this compound later concluded that the chemical formula is (NPC12)3 and the structure is a cyclic trimer form [3-6]. Subsequent research uncovered a number of cyclic homologues in addition to the timer and an "inorganic rubber" that resulted from heating this compound [7-9]. This inorganic rubber, discovered by Stokes, was probably the reactive polymer intermediate that forms the basis for most polyphosphonitrilic chemistry, and its discovery is surprising in light of its great hydrolytic instability and the experimental apparatus available at that time. Development of these compounds has since proceeded slowly because of their distinct differences from their organic counterparts.
