[CuO]+ and [CuOH]2+ Complexes: Intermediates in Oxidation Catalysis?

ConspectusCharacterization of monocopper intermediates in enzymes and other catalysts that attack strong C–H bonds is important for unraveling oxidation catalysis mechanisms and, ultimately, designing new, more efficient catalytic systems. Because initially formed 1:1 Cu/O2 adducts resulting from reactions of Cu(I) sites with O2 react relatively sluggishly with substrates with strong C–H bonds, it has been suggested that reductive O–O bond scission might occur instead to yield more reactive [CuO]+ or protonated [CuOH]2+ cores. Experimental and theoretical studies of [CuO]+ species in the gas phase have provided key insights into the possible reactivity of these species, but detailed information is lacking for discrete complexes with the [CuO]+ or [CuOH]2+ core in solution or the solid state. We describe herein our recent efforts to address this issue through several disparate approaches. In one strategy based on precedent from studies of enzymes and synthetic compounds with iron-α-ketocarboxylate motifs, ...