Wikipedia
Hexachlorophosphazene
Hexachlorophosphazene is an inorganic compound with the formula (NPCl). The molecule has a cyclic backbone consisting of alternating phosphorus and nitrogen atoms. It can be viewed as a trimer of the hypothetical compound N≡PCl. Hexachlorophosphazene together with the related (NPCl) are precursors to inorganic polymers called polyphosphazenes.