High yield synthesis of trinuclear [M 3S 4X 3(diphos) 3] + (M=Mo, W; X=Cl, Br and diphos=dmpe, dppe) molecular clusters from solid state materials. Synthesis and structure of [W 3S 4H 3(dppe) 3](BPh 4)

Abstract

The excision of polymeric {M 3S 7X 4} x (M=Mo, W; X=Cl, Br) cluster phases with diphosphines (dmpe, dppe) in acetonitrile affords a one step general synthetic route for the preparation of trinuclear molecular clusters with formula [M 3S 4X 3(diphos) 3] + (M=Mo, W; X=Cl, Br and diphos=dmpe, dppe) in high yields. Following this strategy, the cluster cations [Mo 3S 4Br 3(dmpe) 3] + and [W 3S 4Br 3(dppe) 3] + have been prepared for the first time. This last tungsten cluster has proved to be a useful synthon for the synthesis of the hydride derivative [W 3S 4H 3(dppe) 3] + in moderate yields. The crystal structure of [W 3S 4H 3(dppe) 3](BPh 4) consists of a equilateral tungsten triangle with one capping and three bridging sulfur atoms defining a incomplete W 3S 4 cuboidal unit in which the tungsten and the sulfur atoms occupy adjacent vertex of a cube with a metal atom missing. The hydride ligand occupies the outer position of the metal in a pseudo-octahedral environment. The other two outer positions on each metal are occupied by the diphosphine phosphorus atoms, located one above and one bellow the M 3 plane resulting in two different 31P{ 1H} NMR signals. Electrochemical studies for all trinuclear clusters reported show one quasi reversible and one irreversible reduction process.