Reversible Reductive Dimerization of Diiron µ-Vinyl Complex via C–C Coupling: Characterization and Reactivity of the Intermediate Radical Species

The diiron mu-vinyl complex [Fe2Cp2(CO)(2)(mu-CO){mu-eta(1):eta(2)-CH=CH(Ph)}]-[BF4], [1][BF4], reacted with CoCp2 affording selectively the C-C coupling product [Fe2Cp2(CO)(2)(mu-CO){mu-CHCH(Ph)}](2). 2. The cation [1](+) was regenerated from 2 in good yield by I-2-induced oxidative cleavage. The cation [1](+) underwent two sequential monoelectron reductions, the first one being an electrochemically reversible process that generated the radical species [Fe2Cp2(CO)(2)(mu-CO){mu-CHCH(Ph)}], [1](center dot). The latter was characterized by EPR spectroelectrochemistry. The structures of [1](+), [1](center dot) and 2 were optimized for the gas phase by DFT calculations. The reaction of [1] [BF4] with NEt3 in the presence of excess PhSSPh gave [Fe2Cp2(CO)(2)(mu-CO){mu-CHCH(Ph)(SPh)}], 3. The new compounds 2 and 3 were fully characterized by IR and NMR spectroscopy, elemental analysis, and X-ray diffraction studies.