Synthesis and Characterization of Bio‐Inspired Diiron Complexes and Their Catalytic Activity for Direct Hydroxylation of Aromatic Compounds

Abstract

AbstractThree [FeFe]‐hydrogenase model complexes [(μ‐dmedt){Fe(CO)3}2] [1; dmedt = SCH(CH3)CH(CH3)S], [(μ‐dmedt){Fe(CO)3}{Fe (CO)2PPh3}] (1‐PPh3), and [(μ‐dmest){Fe(CO)3}2] [1‐O; dmest = SCH(CH3)CH(CH3)S(O)], 1‐O were synthesized and characterized. These model complexes, which are generally used as the functional biomimics of the hydrogen‐producing dinuclear active site in [FeFe]‐hydrogenase, were used as efficient catalysts for the selective hydroxylation of aromatic compounds to phenols under mild conditions. Because both the dithiolato‐sulfur site and the Fe–Fe bond in the model complexes were possible active oxidation sites, DFT calculations were used to investigate the oxygenated products, that is, the S‐oxygenated products or the Fe‐oxygenated forms of the model complexes, which may be involved in the catalytic cycle. The experimental and computational results indicate that the thermodynamically favored Fe‐oxygenated intermediates dominate the hydroxylation of the aromatic compounds. A possible mechanism for the hydroxylation is also proposed.