Reversible reductive dimerization of diiron μ-vinyl complex via C-C coupling: Characterization and reactivity of the intermediate radical species

摘要

vinyl complex [Fe_2Cp_2(CO) _2(μ-CO){μ-η~1:η~2-CH=CH(Ph)}] [BF_4], [1][BF_4], reacted with CoCp_2 affording selectively the C-C coupling product [Fe_2Cp_2(CO) _2(μ-CO){μ-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 [Fe_2Cp_2(CO) _2(μ-CO){μ-CHCH(Ph)}], [1]?. The latter was characterized by EPR spectroelectrochemistry. The structures of [1]~+, [1]~?, and 2 were optimized for the gas phase by DFT calculations. The reaction of [1][BF_4] with NEt_3 in the presence of excess PhSSPh gave [Fe_2Cp_2(CO) _2(μ-CO){μ-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.