Probing the Electronic Structures of [Cu_2(í-XR_2)]^(n+) Diamond Cores as a Function of the Bridging X Atom (X = N or P) and Charge (n = 0, 1, 2)

A series of dicopper diamond core complexes that can be isolated in three different oxidation states ([Cu_2(μ-XR_2)]^(n+), where n = 0, 1, 2 and X = N or P) is described. Of particular interest is the relative degree of oxidation of the respective copper centers and the bridging XR_2 units, upon successive oxidations. These dicopper complexes feature terminal phosphine and either bridging amido or phosphido donors, and as such their metal−ligand bonds are highly covalent. Cu K-edge, Cu L-edge, and P K-edge spectroscopies, in combination with solid-state X-ray structures and DFT calculations, provides a complementary electronic structure picture for the entire set of complexes that tracks the involvement of a majority of ligand-based redox chemistry. The electronic structure picture that emerges for these inorganic dicopper diamond cores shares similarities with the Cu_2(μ-SR)_2 Cu_A sites of cytochrome c oxidases and nitrous oxide reductases.