N2O reduction by the mu4-sulfide-bridged tetranuclear CuZ cluster active site.

Nitrous oxide (N2O) reduction is a chemical challenge both in the selective oxidation of organic substrates by N2O and in the removal of N2O as a green-house gas. The reduction of N2O is thermodynamically favorable but kinetically inert, and requires activating transition-metal centers. In biological systems, N2O reduction is the last step in the denitrification process of the bacterial nitrogen cycle and is accomplished by the enzyme nitrous oxide reductase, whose active site consists of a micro4-sulfide-bridged tetranuclear CuZ cluster which has many unusual spectroscopic features. Recent studies have developed a detailed electronic-structure description of the resting CuZ cluster, determined its catalytically relevant state, and provided insight into the role of this tetranuclear copper cluster in N2O activation and reduction. Copyright 2004 Wiley-VCH Verlag GmbH & Co.