Phosphonitrilics

So, How do you make them?

Treating PCl5 with NH4Cl gives a mixture of oligomers,

Where n is between 3 and 10. The oligomer we wish to use to polymerise is the 6-membered ring. To obtain this you separate the ether soluble cyclic oligomers from the insoluble linear oligomers. The 6-membered ring is the most basic so then extract with HCl to obtain it, then distill to insure a pure product.

Heating this 6-membered ring gives you the polymer,