A One-Hole Cu_4S Cluster with N_2O Reductase Activity: A Structural and Functional Model for Cu_z*

摘要

During bacterial denitrification, two-electron reduction of N_2O occurs at a [Cu_4(μ_4-S)] catalytic site (Cu_z*) embedded within the nitrous oxide reductase (N_2OR) enzyme. In this Communication, an amidinate-supported [Cu_4(μ_4-S)] model cluster in its one-hole (S ＝ ½) 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_2O is reduced by the one-hole duster to produce N_2 and the two-hole cluster, thereby completing a dosed cycle for N_2O 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.