Investigations on the synthesis, structural characterization and electrochemical properties of diiron azadithiolate complexes and phosphine-substituted derivatives

Abstract

Three novel diiron azadithiolate complexes Fe2[(μ-SCH2)2NCH2CH2CH(CH3)2](CO)6 (1), Fe2[(μ-SCH2)2NCH(CH2CH3)2](CO)6 (2) and Fe2[(μ-SCH2)2NCH2CH2CH2SCH3](CO)6 (3) have been synthesized by treatment of Fe2(μ-SCH2OH)2(CO)6 with primary amines RNH2 (R=CH2CH2CH(CH3)2, CH(CH2CH3)2, CH2CH2CH2SCH3). Meanwhile, reaction of Fe2(μ-SCH2OH)2(CO)6 and diphosphine ligand Ph2PCH2PPh2 (dppm), followed by the addition of amines NH2CH2CH2CH(CH3)2 and NH2CH(CH2CH3)2 resulted in the formation of the target phosphine-substituted diiron azadithiolate complexes Fe2[(μ-SCH2)2NCH2CH2CH(CH3)2](CO)5(dppm) (4) and Fe2[(μ-SCH2)2NCH(CH2CH3)2](CO)5(dppm) (5). Complexes 1–5 have been fully characterized by elemental analysis, FTIR, and NMR (1H, 13C, 31P) spectroscopies, and particularly for 1–3 by X-ray crystallography. In addition, complexes 1–5 were found to be catalysts for hydrogen production under electrochemical conditions.