Anionic Tungsten Carbonyl Complexes Containing Dithiocarboxylate, Dithiocarbamate, and Xanthate Ligands

Abstract

The reaction of Et4N[W(CO)5Cl] with sodium dithiobenzoate, ethylxanthate, or various dithiocarbamates gave the corresponding salts Et4N[W(CO)4(SSCX)] (X = Ph, NEt2, N(H)t-Bu, NPh2, OEt) which contain the dithio ligand in a chelating bonding mode. Two of them (X = N(H)t-Bu, NPh2) were characterized by X-ray crystallography. The tungsten atom resides in the center of a slightly distorted octahedron surrounded by a symmetrically bidentate planar dithio ligand and four CO groups. Reaction with PPh3 or PMe3 at elevated temperature gave the tricarbonyl complexes Et4N[W(CO)3(PR3)(SSCX)] and in one case a ring-opened addition product, Et4N[W(CO)4(PMe3)(SC(S)OEt)]. For two of them X-ray structure determinations were carried out. A comparison of the four structures shows that while the W-C bond length decreases progressively with increasing electron density at the tungsten atom, the W-S and W-P bond lengths remain essentially constant.