Molybdenum Dithiolene Complexes: Trinuclear Mixed-Valence Complexes and Geometrical Isomers of Dinuclear Complexes

The reaction of an oxygen- and sulfur-bridged incomplete cubane-type molybdenum complex [Mo3(µ3-S)(µ-S)2(µ-O)(dtp)3(µ-dtp)(CH3CN)] (3) (dtp, diethyl dithiophosphate) with methyl propiolate (HC≡CCOOCH3, MP) and phenyl acetylene (HC≡CC6H5, PA) yields trinuclear mixed-valence Mo3(IV, V, V) complexes [Mo3(O)2(µ3-S)(µ3-SCH=C(COOCH3)S)(dtp)3(µ-OAc)] (3MP) and [Mo3(O)2(µ3-S)(µ3-SCH=C(C6H5)S)(dtp)3(µ-OAc)] (3PA), respectively, and also dinuclear Mo2(V, V) complexes [Mo2(O)2(µ-S)(µ-SCH=C(COOCH3)S)(dtp)2] (2aMP and 2bMP (a geometrical isomer of 2aMP)) and [Mo2(O)2(µ-S)(µ-SCH=C(C6H5)S)(dtp)2] (2aPA and 2bPA (a geometrical isomer of 2aPA)), respectively. The origin of the geometrical isomerism of the dimers comes from the unsymmetric nature of the acetylene derivatives. All of the structures were determined by X-ray crystallography, which revealed that each complex has two carbon-sulfur (µ-S) bonds arising from the adduct formation reaction between complex 3 and an acetylene derivative MP or PA. 1H NMR spectroscopy h...