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The reduction of the compound [Fe2(CO)4(κ2-dmpe){μ-(SCH2)2NBn}] [dmpe = 1,2-bis(dimethylphosphino)ethane], which is considered as an FeI-FeI model of the [2Fe]H subsite of [Fe-Fe]H2ases with a rotated conformation in the solid state, was investigated by cyclic voltammetry. Under reductive conditions, [Fe2(CO)4(κ2-dmpe){μ-(SCH2)2NBn}] undergoes electron-transfer-catalyzed isomerization to afford an isomer featuring a bridging diphosphine [Fe2(CO)4(μ-dmpe){μ-(SCH2)2NBn}]. Comparison of the crystallographic structures of the two isomers affords unique and direct experimental evidence that dissymmetrical coordination of the chelate ligand is required to promote the rotated conformation at one iron atom in this compound. DFT calculations were performed to rationalize this isomerization process and the slightly distorted structure of [Fe2(CO)4(μ-dmpe){μ-(SCH2)2NBn}]. The symmetrization of the coordination sphere results in the disruption of the agostic interaction that stabilized the rotated isomer. [ABSTRACT FROM AUTHOR]

Rotated geometry: The first example of a dinuclear iron(I)–iron(I) complex featuring a fully rotated geometry related to the active site of [Fe–Fe] hydrogenase is reported (see figure). [ABSTRACT FROM AUTHOR]