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

Reaction of the cyclic triphosphenium, ion derived from dppe and PCl3 with SbCl5 did not cause chlorination at the middle phosphorus atom, but has led to isolation of the ionic title compound [Ph2P(Cl)CH2CH2P(Cl)Ph-2](2+)[SbCl5](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. (C) 2002 Elsevier Science B.V. All rights reserved.