Synthesis, crystal structures and electrocatalytic properties of bridgehead-C-functionalized diiron dithiolate complexes

Abstract

To investigate the influence of bridgehead-C functionality in diiron dithiolate complexes on the molecular structure and electrocatalytic properties of [FeFe]-hydrogenase models, three new bridgehead-C-functionalized model complexes 1–3 have been synthesized and structurally characterized. Treatments of parent complex [(μ-SCH2)2CHCO2H][Fe2(CO)6] (A) with the esterification agents o-MeC6H4OH, p-ClC6H4OH, or p-HOC6H4CHO in the presence of 4-dimethylaminopyridine and dicyclohexylcarbodiimide in CH2Cl2 at room temperature resulted in formation of [(μ-SCH2)2CHCO2R][Fe2(CO)6] (R = o-MeC6H4–, 1; p-ClC6H4–, 2; p-OHCC6H4–, 3) in 53–55% yields. The new complexes 1–3 were characterized by elemental analysis, IR and NMR spectroscopy, and especially determined by X-ray crystallography. The electrochemical properties of 1–3 and the electrocatalytic H2 evolution catalyzed by 1 have been investigated by cyclic voltammetry, where 1 is a catalyst for HOAc proton reduction to H2 under electrochemical conditions.