Tuning of the [[[Cu.sub.3]([mu]-O)].sup.4+/5+] redox couple: spectroscopic evidence of charge delocalization in the mixed-valent [[[Cu.sub.3]([mu]-O)].sup.5+] species

Trinuclear [Cu.sup.II]-complexes are prepared and characterized and the effect of substitution of terminal ligands, as well as 4-R groups, in the one-electron oxidation process is examined by using cyclic voltammetry. The results have shown that the triangular, mixed-valent [[[Cu.sub.3]([mu]-O)].sup.5+] intermediate of pMMO catalytic activity might be characterized by its near infrared spectrum, provided it adopts the [super 1][A.sub.1] electronic structure.