Influence of Copper Coordination Spheres on Nitrous Oxide Reductase (NOr) Activity of a Mixed-Valent Copper Complex Containing a {CuS} Core.

A new mixed-valent dicopper complex was generated from ligand exchange by dissolving a bis(CHCN) precursor in acetone. Introduction of a water molecule in place of an acetonitrile ligand was evidenced by base titration and the presence of a remaining coordinated CHCN by IR, F NMR, and theoretical methods. The proposed structure (CHCN-Cu-(SR)-Cu-OH) was successfully DFT-optimized and the calculated parameters are in agreement with the experimental data. has a unique temperature-dependence EPR behavior, with a localized valence from 10 to 120 K that undergoes delocalized at room temperature. The electrochemical signatures are in the line of the other parent and sensibly different from the rest of the series. Similar to the case of , was finally capable of single turnover NO reduction at room temperature. N was detected by GC-MS, and the redox character was confirmed by EPR and ESI-MS. Kinetic data indicate a reaction rate order close to 1 and a rate 10 times faster compared to . is thus the second example of that kind and highlights not only the main role of the Cu-OH motif, but also that the adjacent Cu-X partner (X = OTf in and CHCN in ) is a new actor in the casting to establish structure/activity correlations.