Synthesis and Benzene Hydroxylation Properties of Amino Substituted [FeFe]-Hydrogenase Model Compounds

Abstract

Two novel, amino-substituted [FeFe]-hydrogenase model compounds were synthesized and characterized using IR, NMR, mass and UV–Vis spectroscopies as well as elemental analysis. The electrochemical properties (cyclic voltammetry) and catalytic performances of compounds 1 and 2 for the hydroxylation of benzene were investigated. The reduction peaks of compounds 1 and 2 were observed at − 1.93 V, which agrees with the value of the electron density of diiron centers. Compounds 1 and 2 nearly the same electron density around the Fe–Fe bond, but the position of –NH2 group on the pyridine ring largely influenced the stability. Compound 1 demonstrated a higher phenol yield (equal to 12.8%) than compound 2 (10.2%). The biomimetic catalyst formed by the 4-aminopyridine ligand with two iron nuclei, resembling an enzyme active site, had better stability and higher catalytic activity than the 2-aminopyridine derivative. Compared the catalytic performance of complexes 1–2, despite 1 and 2 have the same electron density around the Fe–Fe bond, the 4-aminopyridine derivative 1 (12.8%) was more stable and with better catalytic activity compared to 2-aminopyridine derivative 2 (10.2%)