Preparation and properties of iodo(trifluoromethyl)phosphine and exchange reactions of some simple trifluoromethylphosphines

Abstract

Iodo(trifluoromethyl)phosphine, F₃CP(H)I, can be prepared by the reaction of iodine with F₃CPH₂, or by exchange between F₃CPH₂ and F₃CPl₂ with which it is in equilibrium. Chlorine reacts with F₃CPH₂ to give F₃CP(H)Cl, (F₃CPH)₂, and HCl. Replacement reactions of iodine in F₃CP(H)I with silver(I) and mercury(II) halides lead to the preparation of mixtures containing F₃CP(H)Cl and of pure F₃CP(H)Br. With Ag[CN] and Hg[CN]₂, F₃CP(H)I gives (F₃CP)₄ and F₃CP(CN)₂ respectively; in the latter case there is evidence for a mercury–phosphorus intermediate. The diphosphane (F₃CPH)₂ can be prepared by reduction of F₃CP(H)I with mercury or by its reaction with SbF₃, CdF₂, or NaF. Reactions between all possible pairs of compounds F₃CPX₂–F₃CPY₂(X or Y = F, Cl, Br, I, H, or CN) give the mixed species F₃CP(X)Y, characterised by n.m.r. spectroscopy, in all cases except when X = F and Y = H, I or CN, although the reaction is often more complex than simple exchange. The vibrational spectra of F₃CP(H)X and F₃CP(D)X (X = Br or I) have been analysed in terms of group vibrations.