Theoretical perspective on mononuclear copper-oxygen mediated C–H and O–H activations: A comparison between biological and synthetic systems

Abstract

Dioxygen activations constitute one of core issues in copper-dependent metalloenzymes. Upon O 2 activation, copper-dependent metalloenzymes such as particulate methane monooxygenases (pMMOs), lytic polysaccharide monooxygenases (LPMOs) and binuclear copper enzymes PHM and DβM, are able to perform various challenging C–H bond activations. Meanwhile, various copper-oxygen core containing complexes have been synthetized to mimic the active species of metalloenzymes. Dioxygen activation by mononuclear copper active site may generate various copper-oxygen intermediates, including Cu(II)-superoxo, Cu(II)-hydroperoxo, Cu(II)-oxyl as well as the Cu(III)-hydroxide species. Intriguingly, all these species have been invoked as the potential active intermediates for C–H/O–H activations in either biological or synthetic systems. Due to the poor understanding on reactivities of copper-oxygen complex, the nature of active species in both biological and synthetic systems are highly controversial. In this account, we will compare the reactivities of various mononuclear copper-oxygen species between biological systems and the synthetic systems. The present study is expected to provide the consistent understanding on reactivities of various copper-oxygen active species in both biological and synthetic systems. Reactivities of various mononuclear copper-oxygen have been compared between the synthetic and biological systems, showing that all species are reactive toward O–H activations but only [CuO] + species could be responsible for C–H activations in monooxygenases.