Coordinations of vinyltetrahydrothiophene to a trirhenium cluster

The reaction of Re3(CO)10(NCMe)2(μ-H)3 with 2-vinyltetrahydrothiophene (VTHT) at 25°C for 22 h yielded two products: Re3(CO)10(μ-H)3(μ-S(CH2)3CHCHCH2) (1; 50% yield), and Re3(CO)9(μ-H)3(μ-η3-S(CH2)3CHCHCH2) (2; 12% yield). Compound 1 exists in solution as a mixture of isomers in a dynamic equilibrium at room temperature. One of the isomers of 1 and 2 were characterized by single-crystal X-ray diffraction analyses. Compound 1 contains a triangular trirhenium cluster with ten linear terminal carbonyl ligands, three bridging hydride ligands and a bridging vinyltetrahydrothiophene ligand coordinated to two metal atoms by using both of the lone pairs of the electrons on the sulfur atom of the vinyltetrahydrothiophene molecule. Compound 2 contains a triangular cluster of three rhenium atoms and a triple-bridging vinyltetrahydrothiophene ligand that is coordinated to two of the rhenium atoms through the sulfur atom and a π-coordination of the vinyl group to the third metal atom. In both complexes there is a bridging hydride ligand across each of the three rhenium–rhenium bonds in the cluster. Facile interconversion of the two isomers of 1 was observed by 2D EXSYS 1H-NMR spectroscopy. Compound 2 can be obtained from 1 in 98% yield via thermal decarbonylation by refluxing a solution in methylene chloride for 18 h.