Characterization of copper 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. New insights into the nature of such intermediates may be obtained through the design, synthesis, and characterization of copper-oxygen complexes. Two key proposed examples contain [CuO2]+ and [CuOH]2+ cores, which have been suggested as possible reactive intermediates in monocopper enzymes such as lytic polysaccharide monooxygenase.