Ligand Exchange in Tungsten−Rhenium Acetylide Complexes (C5Me5)WRe(μ-X)(CCPh)(CO)5, X = Br, I, SPh, and O2CMe, and the Conversion to Complexes LWRe(μ-SO2Ph)(CCPh)(CO)5, L = Cp and C5Me5, Bearing a Sulfinate Bridge via Oxidation Using Hydrogen Peroxide

Heterobimetallic acetylide compounds (C 5 Me 5 )WRe(μ-X)(CCPh)(CO) 5, X = I and Br ( 1a, b ), were obtained in high yields from the combination of (C 5 Me 5 )W(CO) 3 (CCPh) and Re(CO) 5 X, X = Br and I. These complexes possess a nearly symmetrical halide bridge and an acetylide ligand, linked to the W atom via σ-bonding and to the Re atom via a π-interaction. The conversion to the corresponding thiolate and acetate complexes LWRe(μ-X)(CCPh)(CO) 5 [L = C 5 Me 5, X = SPh ( 2a ) and O 2 CMe ( 3 ); X = SPh, L = Cp ( 2b )] was realized by reactions of the halide complexes with thiophenol or with acetic acid, respectively, in the presence of triethylamine or pyridine. Related reactions of (C 5 Me 5 )W(CO) 3 (CCPh) with [Re(CO) 4 (μ-SPh)] 2 or with [Re(CO) 4 (μ-O 2 CMe)] 2 afforded the identical thiolate and acetate complexes through a reaction sequence involving the dissociation of these dimeric starting materials. Reactions of 1 − 3 with P(OMe) 3 were also examined, and only the thiolate complex 2a gave the isolated monosubstituted complex (C 5 Me 5 )WRe(μ-SPh)(CCPh)(CO) 4 [P(OMe) 3 ] ( 4 ) in good yield. Oxidation of the bridging thiolate ligand in 2a, b using 30% H 2 O 2 solution yielded sulfinate complexes with the formula LWRe(μ-SO 2 Ph)(CCPh)(CO) 5, L = C 5 Me 5 ( 6 ) and L = Cp ( 7, 8 ). Two linkage isomers were characterized by single-crystal X-ray diffraction studies: One bears a μ-η 2 -SO 2 Ph ligand with the bridging oxygen atom coordinated to the W atom, while in the second the bridging oxygen atom is coordinated to the Re atom. The isomerization caused by the interchange of the bridging and the terminal oxygen atom of the sulfinate group is discussed.