An investigation on catalytic nitrite reduction reaction by bioinspired Cu^II complexes

Catalytic nitrite reductions by Cu^II complexes containing anionic ^Me2Tp, neutral ^Me2Tpm, or neutral TIC ligands in the presence of L-ascorbic acid, which served as an electron donor and proton source, were investigated. The results showed that auxiliary ligands are important for copper-mediated catalytic nitrite reduction. Furthermore, the electronic effects of the ligand govern the nitrite reduction efficiency, which should be considered at two control points: one is the susceptibility of the LCu^I-nitrite species to protonation and the other is the susceptibility of LCu^II to reduction giving LCu^I. In addition, an external strong acid leads to the production of nitrous acid, which may suggest that the reactivity of nitrous acid toward the LCu^I species is a third control point.