Mono- and di-substituted [FeFe]-hydrogenase H-cluster mimics bearing the 3,4-dimercaptobenzaldehyde bridge moiety: Insight into synthesis, characterization and electrochemical investigations

Abstract

This report describes the synthesis and characterization of [FeFe]-hydrogenase mimic, namely [Fe2(CO)6{μ-bdtf}] (2, bdtf = 3,4-dimercaptobenzaldehyde) obtained from the reaction of 3,4-dimercaptobenzaldehyde with Fe3(CO)12. Moreover, treatment of complex 2 with PPh3 ligand yielded both mono- and disubstituted complexes [Fe2(CO)5PPh3{μ-bdtf}] (3), [Fe2(CO)4(PPh3)2{μ-bdtf}] (4), while in the case of P(OMe)3 ligand afforded only the disubstituted complex [Fe2(CO)4(P(OMe)3)2{μ-bdtf}] (5). The molecular structures of complexes 2–5 were confirmed by X-ray diffraction analysis. Furthermore, the influence of the substituent on the benzene ring as well as at the iron center on the electrochemistry and catalysis of these mimics toward proton reduction have been evaluated by cyclic voltammetry. All complexes show their potentials toward hydrogen formation in the presence of weak acid, such as acetic acid (AcOH).