Influence of Copper Coordination Spheres on Nitrous Oxide Reductase (N2Or) Activity of a Mixed-Valent Copper Complex Containing a {Cu2S} Core

A new mixed-valent dicopper complex [5] was generated from ligand exchange by dissolving a bis(CH 3 CN) precursor [3] 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 CH 3 CN by IR, 19 F NMR, and theoretical methods. The proposed structure (CH 3 CN-Cu-(SR)-Cu-OH 2 ) was successfully DFT-optimized and the calculated parameters are in agreement with the experimental data. [5] 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 aquo paren [2] and sensibly different from the rest of the series. Similar to the case of [2] , [5] was finally capable of single turnover N 2 O reduction at room temperature. N 2 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 [2] . [5] is thus the second example of that kind and highlights not only the main role of the Cu-OH 2 motif, but also that the adjacent Cu-X partner (X = OTf - in [2] and CH 3 CN in [5] ) is a new actor in the casting to establish structure/activity correlations.