Structure and stability of cyano-derivatives of organochlorophosphate(V) ions

Abstract

The organochlorophosphate(V) ions [PRCl₅]^–(R = Et, C₆F₅, or CCl₃) react with excess AgCN to form [PEt(CN)₅]^–, [P(C₆F₅)Cl(CN)₄]^–(one isomer), and [P(CCl₃)Cl₂(CN)₃]^–(all three isomers) respectively; salts containing these ions have been isolated and characterised. Several intermediate chlorocyanophosphates have been detected by ³¹P n.m.r. spectroscopy and isomeric configurations have been assigned by the method of pairwise interactions. A possible rationalisation of the degree of substitution by cyanide into these and other organochlorophosphates is proposed, based on the relative stabilities of the six-co-ordinate anions and the five-co-ordinate phosphoranes from which they are derived.