Diphosphine ligand‐containing model complex of [Fe]‐H2ase active site as direct phenol hydroxylation catalyst in the aqueous phase

Abstract

AbstractBACKGROUNDDihydroxybenzene (DHB) is a common feedstock in the pharmaceutical and dyestuff industries, which can be prepared by hydroxylation of phenol. It has great potential to find a highly selective catalyst to promote this process.RESULTSTwo novel model complexes, FeI2(CO)2DPPE (1) and FeI2(CO)2DPPP (2), were designed and synthesized, which mimic the active site of [Fe]‐hydrogenase. IR and UV–vis spectroscopies and single‐crystal X‐ray diffraction were used to characterize the structures of complexes 1 and 2. According to the IR spectra, complexes 1 and 2 have two cis‐CO ligands, which is similar to the Fe‐GP cofactor isolated from the enzyme. The single‐crystal X‐ray diffraction analysis of complex 1 revealed an angle of 93.7° between the two cis‐CO ligands, confirming the structural similarity to the active site of natural [Fe]‐H2ase. Complex 1 exhibits excellent catalytic properties in phenol hydroxylation, achieving 19.6% phenol conversion and 82.5% DHB selectivity under optimal conditions.CONCLUSIONSComplex 1 is an excellent candidate for mild phenol hydroxylation catalysis. Additionally, a proposed mechanism for hydroxylation catalyzed by complex 1 is presented. © 2021 Society of Chemical Industry (SCI).