Mono- and dinuclear mimics of the [FeFe] hydrogenase enzyme featuring bis(monothiolato) and 1,3,5-triaza-7-phosphaadamantane ligands

Abstract Two new complexes [Fe2(µ-SC6H4CH3-p)2(CO)5(PTA)] 1 and [Fe(κ1-SC6H4CH3-p)2(CO)2(PTA)2] 2 with bis(monothiolato) ligands, resembling the active site of iron hydrogenases have been synthesized and analyzed for proton reduction activity using cyclic voltammetric techniques. The structure and geometry of the complexes have been studied by spectroscopic, crystallographic and computational analysis. The influence of bis(monothiolato) and bulky electron-donating phosphine ligands on electrocatalytic proton reduction process was examined. Both the complexes were found to be potent electrocatalysts with CECE or ECC(on S-atom)E (for 1) and CEEC(C) (for 2) mechanisms for hydrogen production.