Studies of phosphazenes. Part 31. Kinetic studies of the reactions of hexachlorocyclotriphosphazene with aromatic primary amines: evidence for the intermediacy of a reactive three-co-ordinated phosphorus(V) species

Abstract

Kinetic studies of the reactions of hexachlorocyclotriphosphazene with aromatic primary amines(aniline, p-toluidine, and p-anisidine) have been investigated with a view to developing ‘model systems’ for analogous reactions with aromatic diamines. The first and second stages of chlorine replacement proceed by an SN2(P) mechanism in both tetrahydrofuran (thf) and methyl cyanide. Kinetic evidence is obtained for a base-catalysed E1(c.b.) mechanism for the formation of geminal products in thf in the presence of an excess of tri-n-butylamine. The intermediacy of a three-co-ordinate PV species is established by trapping experiments with methanol and by the isolation of the unusual products [NHEt3][gem-N3P3CL4(NHR)(O)][R = Ph, C6H4Me-p, or C6H4(OMe)-p]. These triethylammonium salts on dimethylaminolysis afford the hydroxy derivatives gem-N3P3(NHR)(OH)(NMe2)4, which exist in their oxophosphazadiene tautomeric forms.