Formation of a Dithiophosphinate Ligand Ph2PS2 by Sulfur Insertion into the Metal−Phosphido Bond on Heterobimetallic Phosphido-Bridged Complex Cp(CO)2W(μ-PPh2)Mo(CO)5: A Rare Example of a Neutral Six-Electron Mixed-Metal Cluster with a Mo2WS4 Core

Abstract

Reflux of a dichloromethane solution of elemental sulfur and phosphido-bridged heterodinuclear complex (1) afforded (2) and a neutral six-electron mixed-metal incomplete cubane-like cluster, CpW(μ3-S)(μ-S)2Mo2(μ-S)(μ-S2PPh2)(S2PPh2)2 (3), together with known compounds Cp(CO)3W(μ-PPh2)Mo(CO)5 and (CpW(S)(μ-S))2. The electron-deficient 28e heterodinuclear complex 2 is stabilized via S(pπ) → Mo(d) ligand-to-metal dative π-bonding interactions. Room-temperature stirring of a THF solution of 2 and DMAD (dimethyl acetylenedicarboxalate) yielded compounds (4) and (5). Compounds 2−5 were characterized by single-crystal X-ray diffraction analysis. Molecular structures of 2 and 3 reveal sulfur insertion into the metal−phosphido bond on 1, resulting in a dithiophosphinate ligand Ph2PS2. Formation of the C−S bonds in 4 and 5 has resulted through the reaction of sulfide ligands on 2 and DMAD.