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 (C₅Me₅)WRe(μ-X)(CCPh)(CO)₅, X = I and Br (1a,b), were obtained in high yields from the combination of (C₅Me₅)W(CO)₃(CCPh) and Re(CO)₅X, 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 = C₅Me₅, X = SPh (2a) and O₂CMe (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 (C₅Me₅)W(CO)₃(CCPh) with [Re(CO)₄(μ-SPh)]₂ or with [Re(CO)₄(μ-O₂CMe)]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 (C₅Me₅)WRe(μ-SPh)(CCPh)(CO)₄[P(OMe) ₃] (4) in good yield. Oxidation of the bridging thiolate ligand in 2a,b using 30% H₂O₂ solution yielded sulfinate complexes with the formula LWRe(μ-SO₂Ph)(CCPh)(CO)₅, L = C₅Me₅ (6) and L = Cp (7, 8). Two linkage isomers were characterized by single-crystal X-ray diffraction studies: One bears a μ-η²-SO₂Ph 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.