Mechanism of Reduction of the Nitrite Ion by CuI Complexes

The reaction of Cu+aq with NO2− was studied. The results are consistent with the mechanism: Cu+aq + NO2− →← (Cu+NO2−), K = 140 ± 30 M−1; (Cu+NO2−) + H+ → Cu2+ + NO + OH−, k = 4.6 × 105 M−1s−1. It is proposed that the copper is bound to the nitrogen in the transient complex (Cu+NO2−). In addition, the reaction was studied with (CuILi)+ complexes. The results show that the ligands reduce the value of K and that their effect on k depends on the redox potential of the (CuII/ILi) couple. This reaction is the simplest model for the CuNIR (NIR = Nitric reductase) enzymes. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)