[FeFe]‐Hydrogenase models featuring dithiolato‐bridgehead functionality: Preparation, structures, and electrocatalytic proton reduction

Abstract

To further develop the active site models of [FeFe]-hydrogenases, a new series of diiron model complexes [{(μ-SCH 2 ) 2 CHCH 2 OC(O)C 6 H 4 I)}Fe 2 (CO) 6 ] (I is located at -para for 1, -meta for 2, and -ortho for 3) bearing dithiolato-bridgehead functionality were successfully prepared by treatments of bridghead-hydroxyl-containing parent complex [{(μ-SCH 2 ) 2 CHCH 2 OH)} Fe 2 (CO) 6 ] (A) and three different iodobenzoic acids (IC 6 H 4 CO 2 H) in the presence of 4-dimethylaminopyridine (DMAP) as catalyst and dicyclohexylcarbodiimide (DCC) as dehydrating reagent. All these new complexes 1-3 have been fully characterized through elemental analysis, FT-IR and NMR ( 1 H, 13 C) spectroscopies, and X-ray crystallography. Further electrochemical and electrocatalytic properties of complexes 1-3 are studied and compared in the absence and presence of acetic acid (HOAc) as a proton source by cyclic voltammetry (CV), indicating that they may be considered as the active biomimetic electrocatalysts for proton reduction to hydrogen (H 2 ).[a] S.-F. Bai, X.