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

BACKGROUND Dihydroxybenzene (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. RESULTS Two novel model complexes, FeI 2 (CO) 2 DPPE ( 1 ) and FeI 2 (CO) 2 DPPP ( 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]-H 2 ase. Complex 1 exhibits excellent catalytic properties in phenol hydroxylation, achieving 19.6% phenol conversion and 82.5% DHB selectivity under optimal conditions. CONCLUSIONS Complex 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).