Synthesis, Structures and Electrochemical Properties of Nitro‐ and Amino‐Functionalized Diiron Azadithiolates as Active Site Models of Fe‐Only Hydrogenases

Complex [{(μ‐SCH 2 ) 2 N(4‐NO 2 C 6 H 4 )}Fe 2 (CO) 6 ] ( 4 ) was prepared by the reaction of the dianionic intermediate [(μ‐S) 2 Fe 2 (CO) 6 ] 2− and N , N ‐bis(chloromethyl)‐4‐nitroaniline as a biomimetic model of the active site of Fe‐only hydrogenase. The reduction of 4 by Pd‐C/H 2 under a neutral condition afforded complex [{(μ‐SCH 2 ) 2 N(4‐NH 2 C 6 H 4 )}Fe 2 (CO) 6 ] ( 5 ) in 67 % yield. Both complexes were characterized by IR, 1 H and 13 C NMR spectroscopy and MS spectrometry. The molecular structure of 4 , as determined by X‐ray analysis, has a butterfly 2Fe2S core and the aryl group on the bridged‐N atom slants to the Fe(2) site. Cyclic voltammograms of 4 and 5 were studied to evaluate their redox properties. It was found that complex 4 catalyzed electrochemical proton reduction in the presence of acetic acid. A plausible mechanism of the electrocatalytic proton reduction is discussed.