Compounds of stoichiometric composition [X2PN]n, in which X is alkoxy, halogen, or other electronegative group, and n is a variable integer, the value of which may not be known.
See: phosphazenes
PAC, 1995, 67, 1307. 'Glossary of class names of organic compounds and reactivity intermediates based on structure (IUPAC Recommendations 1995)' on page 1358 (