Catalysis of the Reduction of O2 to H2O by Vanadium-Schiff Base complexes in Acetonitrile

摘要

In recent reports, we described the acid-induced disproportionation of V~(IV)O(salen) (H2salen = N,N-ethylenebis(salicylideneamine)) in acetonitrile to form V~VO(salen)~+ and V~(III)(salen)~+. The stoichiometry and kinetics of the reaction between V~(III)(salen)~+ and O2 were also examined. The possible application of these complexes in the catalytic reduction of was noted but not pursued because of the instability of the V~(III)(salen)~+ complex and the low rate of its reaction with O2. The novelty of the chemistry involved in the catalysis provided an impetus for an expanded study of analogous vanadium complexes of other Schiff base ligands modified to enhance the stability and catalytic activity of their vanadium complexes. A variety of oxovanadium(IV) complexes with different Schiff base ligands, V~(IV)O(SB) (SB = Schiff base), have been synthesized and examined as catalysts for the catalytic reduction of O2. Performance much superior to that of salen-based catalysts was achieved.