Addition of paraformaldehyde to phosphonodihydrazides PhP(X)(NCH3NH2)(2), 1a (X = S) or 1b (X = O), led to 1,2,4,5,3-perhydrotetrazaphosphorines 4a or 4b and then to stable phosphonodihydrazones PhP(X)(N(CH3)N=CH2)(2), 6a (X = S) or 6b (X = O). Similarly, addition of paraformaldehyde to the hexahydrazino cyclotriphosphazene N3P3(NCH3NH2)(6) afforded a tris(1,2,4,5,3-perhydrotetrazaphosphorine 12, which in turn is transformed to the stable hexakis(N-methyleneamine)cyclotriphosphazine 13 by addition of paraformaldehyde. The crystal and molecular structure of 13 was examined by single crystal X-ray diffraction. Treatment of 6a or 6b with the phosphanylium ion (iPr(2)N)(2)P+CF3SO3-, 15, gave a mixture of bicyclic phosphonium salts 17 and 18 or 19 and 20 respectively. A pyridinium salt 21 was prepared by reacting 6a with trifluoro acetic anhydride in the presence of pyridine. Interaction of the borenium salt (C5H9)(2)B+CF3SO3-, 22, with 6a led to the salt 23 [6a.2B(C5H9)(2).CF3SO3].