Condensation of diaminomaleonitrile with PCl3, ME2NPCl2< (Me2N)2PCl, (Me2N)3P or (Et2N)3P yields the 4,5-dicyano 1,3,2-diazaphosphole ring. In a slower reaction the two cyano groups by adding Me2NH or Et2NH form a second fivemembered ring to give 1,3,5,2-triazaphosphapentalenes.