The phosphorylation of a series of diaminopyridines (2,3-, 3,4-, 2,5- and 2,6-diaminopyridine), with various molecular equivalents of chlorodiphenylphosphine in the presence of TEA has been studied. Notably, phosphorylation of 2,3- and 3,4-diaminopyridine affords compounds with diphosphinoamine (P-N-P) and iminobiphosphine (N=P-P) entities co-existing in the same molecule. Phosphorylations of 2,5- and 2,6-diaminopyridine afford compounds containing only diphosphinoamine units. The solid-state structure of three compounds has been determined including the first example of a crystallographically characterized compound containing both a diphosphinoamine group and an iminobiphosphine group in the same structure.