Water as a proton mediator for dioxygen-selective oxidation of alcohols by a planar dinuclear butterfly-like Cu[sbnd]Cu bonding complex: A combined experimental and computational study

Abstract

The selective catalytic oxidation of alcohols is important both in laboratory and industrial production, and traditional oxidants cause environmentally lethal wastes. The development of dioxygen selective oxidation efficient has been pursued from atom-efficient, economic and environmental view of points. Using DFT calculation and ESI-MS experiments, we studied the activation of the CuCu bonded planar complex Cu2(ophen)2 to dioxygen and the application of the dioxygen-copper system for the selective oxidation of alcohols. For practical application and green chemistry, this catalytic system avoided the use of a large excess of base and expensive nitroxyl derivatives. In the cycle of oxidation, two oxidative dehydrogenation processes featuring superoxide/peroxide (I) and hydroperoxide (II) occurred along with a series of conformational changes of the butterfly-like Cu-complex from stretched to folded to stretched. Additionally, we characterized the role of the water molecule asa proton mediator in the dioxygen-copper system.