Reactions of dithiolate ligands in mononuclear complexes of rhenium(V)

Article abstract of DOI:10.1021/ja020125z

The thermal reactions of the Re(V) dithiolate complex Cp′ReCl₂(SCH₂CH₂S), 1 (where Cp′ = EtMe₄C₅), and related derivatives have been studied. When 1 is heated in toluene in a sealed evacuated tube at 100°C, a dehydrogenation reaction occurs to form a new rhenium complex with a dithiolene ligand, Cp′ReCl₂(SCHCHS), 6, in ca. 40% yield. The structure of 6 has been confirmed by an X-ray diffraction study. Under the thermal conditions studied, 1 also undergoes an olefin extrusion reaction. Free ethene is detected in the NMR spectrum of the products, and insoluble rhenium products are also formed. When 1 is reacted with excess ethene under mild conditions, a new organic product, 1,4-dithiane, is formed. Complex 1 is also found to react with oxidants, such as O₂ and S₈, under mild conditions to form the dehydrogenation product 6. Kinetic studies of the thermal reaction of 1 and related derivatives have been completed, and possible mechanisms for the thermally induced dehydrogenation reaction are discussed.