LAUSR

Abstract μ-(SCH(CH 2 CH 3 )CH 2 S)-Fe 2 (CO) 4 (κ 2 -DPPE) (complex 1, DPPE is 1,2-bis (diphenylphosphor) ethane), which can be regarded as a model of the [FeFe]‑hydrogenase active site, was synthesized and characterized. The reversible isomerization of complex 1 under N 2 and CO atmosphere was demonstrated by cyclic voltammetry, IR spectroscopy and 31 P NMR. Furthermore, we discovered that both the presence of a CO atmosphere and the addition of H 2 O can independently trigger the same inversion of configuration of complex 1 . The electrocatalytic proton reduction capacity of 1 was evaluated under varying conditions. It was found that addition of a little H 2 O to CH 3 CN can facilitate its efficiency of electrocatalytic proton reduction. The possible mechanism of transition between axial/basal and dibasal isomers and the function of H 2 O in the electrocatalytic reaction are discussed.