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

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.