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 $S_N2(P)$ mechanism in both tetrahydrofuran (thf) and methyl cyanide. Kinetic evidence is obtained for a base-catalyzed $E_1(c.b.)$ mechanism for the formation of geminal product in thf in the presence of an excess of tri-n-butylamine. The intermediacy of a three-coordinate $P^V$ species is established by trapping experiments with methanol and by the isolation of the unusual products $[NHEt_3]$ $[gem-N_3P_3Cl_4(NHR)(O)]$ $[R = P4, C_6H_4Me_{-p}$ or $C_6H_4{(OMe)}_{-p}]$. These triethylammonium salts on dimethylaminolysis afford the hydroxy derivatives ${gem-N}_3P_3$ $(NHR)(OH){(NMe_2)}_4$, which exist in their oxophosphazadiene tautomeric forms