what are PhosphazineCompounds

these compounds are also called  Phosphonitrilic Compounds

Although there are many compounds that contain phosphorus and nitrogen, the phosphazines or phosphonitrilic compounds are unique. Because both N and P have fi ve electrons in the valence shell, it is possible to have a six-membered heterocyclic ring in which the phosphorus atoms are bonded to two other atoms. Phosphazines having both linear and cyclic structures have been prepared. Historically, chlorides having the general formula (PNCl 2 ) n were the fi rst compounds of this type prepared, and the original preparation of (PNCl 2 ) n was carried out in 1832 by J. von Liebig using the reaction of NH 4 Cl and PCl 5 .