DFT studies on the mechanism of veratryl alcohol oxidation catalyzed by Cu–phen complexes

Abstract

Density functional theory (DFT) calculations have been performed to investigate the catalytic mechanism for the oxidation of veratryl alcohol to veratraldehyde by Cu–phen (phen = 1,10-phenanthroline) catalyst. The catalytic cycle consists of alcohol oxidation and O₂ reduction. For the alcohol oxidation, both mononuclear mechanism (path A) and binuclear mechanism (path B) are proposed. Our calculations show that path B is preferred over path A. Namely, for the Cu–phen (phen = 1,10-phenanthroline) catalytic system, the mechanism is the binuclear mechanism, which is consistent with the experimental suggestion. For the O₂ reduction, two possible paths are proposed as well, which are (1) “path I” in which Cu^I is oxidized by O₂ via a binuclear mechanism, and (2) “path II” in which Cu^I is oxidized by O₂ via a mononuclear mechanism. According to our calculations, path I is favored both in thermodynamics and kinetics.