An unexpected reaction product; the crystal and molecular structure of 1,2-bis(chlorodiphenylphosphonium)ethane pentachloroantimonate(III)

Abstract

Reaction of the cyclic triphosphenium ion derived from dppe and PCl 3 with SbCl 5 did not cause chlorination at the middle phosphorus atom, but has led to isolation of the ionic title compound [Ph 2P(Cl)CH 2CH 2P(Cl)Ph 2] 2+ [SbCl 5] 2−, the structure of which has been ascertained by X-ray crystallography. The cation has been structurally characterised for the first time; the geometry about each phosphorus atom is approximately tetrahedral, with a slightly larger angle between the bulky phenyl groups than between the other ligands. The pentachloroantimonate(III) anion exists as an isolated species, with a stereochemically active lone pair. This gives an approximately square pyramidal structure, with the shortest SbCl bond trans to the lone pair position.