A One-Hole Cu₄S Cluster with N₂O Reductase Activity: A Structural and Functional Model for Cu_Z*

Abstract

During bacterial denitrification, two-electron reduction of N 2 O occurs at a [Cu 4 (μ 4 -S)] catalytic site (Cu Z *) embedded within the nitrous oxide reductase (N 2 OR) enzyme. In this Communication, an amidinate-supported [Cu 4 (μ 4 -S)] model cluster in its one-hole ( S = 1 / 2 ) 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 4 (μ 4 -S)] model complexes with catalytically relevant oxidation states for the first time. More importantly, N 2 O is reduced by the one-hole cluster to produce N 2 and the two-hole cluster, thereby completing a closed cycle for N 2 O reduction. Not only is the title complex thus the best structural model for Cu Z * to date, but it also serves as a functional Cu Z * mimic.