A Cu₄S model for the nitrous oxide reductase active sites supported only by nitrogen ligands

Abstract

To model the (His)7Cu4Sn (n = 1 or 2) active sites of nitrous oxide reductase, the first Cu4(μ4-S) cluster supported only by nitrogen donors has been prepared using amidinate supporting ligands. Structural, magnetic, spectroscopic, and computational characterization is reported. Electrochemical data indicates that the 2-hole model complex can be reduced reversibly to the 1-hole state and irreversibly to the fully reduced state.

N2O Reductase Activity of a [Cu4S] Cluster in the 4CuI Redox State Modulated by Hydrogen Bond Donors and Proton Relays in the Secondary Coordination Sphere

“…This 4Cu I complex lacks any well‐defined redox chemistry or N 2 O reactivity but, separately, has shown intriguing photochemical properties . Our group recently accessed the 2Cu I :2Cu II and 3Cu I :1Cu II redox states of a [Cu 4 (μ 4 ‐S)] cluster using the bridging formamidinate ligands [(2,4,6‐Me 3 C 6 H 2 N) 2 CH] − , but the 4Cu I state that would model the active form of Cu Z was unstable and could not be accessed synthetically.…”

Probing the electronic and mechanistic roles of the μ4-sulfur atom in a synthetic CuZ model system

“…Finally, a formamidinate-supported [Cu 4 S] cluster in its formally 3Cu I :1Cu II ([4Cu:1S] 1À ) state was found to reduce 15 N 2 O to 15 N 2 (Scheme 1b). 22,23 Here the m 4 -sulde bridge remained intact during a formal oxidation to the 2Cu I :2Cu II ([4Cu:1S] 0 ) redox state of the cluster, allowing us to establish a closed cycle for N 2 O reduction. Based on these results, the potential role (or lack thereof) of the bridging sulde ligand in copper-sulfur clusters merits further investigation.…”

A magnetic self-contained thermochromic system with convenient temperature range

“…The thermochromic Oh-Td switching in Co 2+ complexes should also be accompanied by a significant change in the magnetic moment in line with the loss of orbital contribution on switching from the orbital triplet (octahedral) to the orbital singlet (tetrahedral), 18 Figure 3. 1 H NMR is a useful method to determine magnetic moment in solution 19,20 and here the Evans' method was used to determine the magnetic moment across the temperature range of the thermochromic switching, yielding textbook values for the orbital singlet and triplet forms at 70 and 30°C respectively, Table 1 and Figure 4 (Figures S9-S10). By containing the change in coordination number within the ionic liquid, the only input required to effect the change in moment is temperature, i.e.…”