The reactions of bis(dichlorophosphinyl)methylamine, [Cl2P(:O)]2NMe, with dimethylamine and with NN-dimethyl(trimethylsilyl)amine have been studied. Mono, non-geminal bis-, tris-, and tetrakis-dimethylaminoderivatives have been identified; the bis-derivative has been separated into diastereomeric forms which interconverted either when heated, or in the presence of tetraethylammonium chloride. The mono-derivative was also obtained from the reactions of phosphoryl halides with heptamethyldisilazane, (Me3Si)2NMe, and the geminal bis- and the tris-derivatives were obtained from the condensation reactions of (Me2N)2P(:O)·NHMe with phosphoryl chloride and Cl2P(:O)·NMe2, respectively. Structures were established by 1H and 31P n.m.r. spectroscopy and the results compared with those obtained for the dimethylaminolysis of hexachlorocyclotriphosphazatriene, N3P3Cl6.