A One-Hole CuS Cluster with NO Reductase Activity: A Structural and Functional Model for Cu.

During bacterial denitrification, two-electron reduction of NO occurs at a [Cu(μ-S)] catalytic site (Cu*) embedded within the nitrous oxide reductase (NOR) enzyme. In this Communication, an amidinate-supported [Cu(μ-S)] model cluster in its one-hole (S = /) redox state is thoroughly characterized. Along with its two-hole redox partner and fully reduced clusters reported previously, the new species completes the two-electron redox series of [Cu(μ-S)] model complexes with catalytically relevant oxidation states for the first time. More importantly, NO is reduced by the one-hole cluster to produce N and the two-hole cluster, thereby completing a closed cycle for NO reduction. Not only is the title complex thus the best structural model for Cu* to date, but it also serves as a functional Cu* mimic.