Diiodophosphoranes. Synthesis and structure in the solid state and in solution

Abstract

Nineteen diiodophosphoranes, R₃PI₂(R₃= Ph₃, substituted triaryl, mixed arylalkyl, or trialkyl), the vast majority of which have previously not been reported, are described. Their ³¹P{H} NMR data indicate an ionic [R₃PI]I structure in CDCl₃ solution, in keeping with results of other solution studies of a limited number of dihalogenophosphoranes, but solid-state ³¹P-{H} magic angle spinning NMR data for R₃PI₂(R₃= Ph₃, PhMe₂ or Me₃) indicate a molecular four-co-ordinate R₃P–I–I structure, strongly suggesting that this is the common structure for diiodophosphoranes, and not the five-co-ordinate trigonalbipyramidal structure of conventional wisdom.