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

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• 作者：Nicole Gagnon ; William B. Tolman
• 刊名：Accounts of Chemical Research
• 出版年：2015
• 出版时间：July 21, 2015
• 年：2015
• 卷：48
• 期：7
• 页码：2126-2131
• 全文大小：344K
• ISSN：1520-4898

文摘

Characterization of monocopper intermediates in enzymes and other catalysts that attack strong C鈥揌 bonds is important for unraveling oxidation catalysis mechanisms and, ultimately, designing new, more efficient catalytic systems. Because initially formed 1:1 Cu/Ob>2b> adducts resulting from reactions of Cu(I) sites with Ob>2b> react relatively sluggishly with substrates with strong C鈥揌 bonds, it has been suggested that reductive O鈥揙 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-伪-ketocarboxylate motifs, reactions of Ob>2b> with Cu(I)-伪-ketocarboxylate complexes were explored, with the aim of identifying reaction pathways that would implicate the intermediacy of a [CuO]⁺ species. A second approach focused on the reaction of N-oxides with Cu(I) complexes, with the goal being to elicit O鈥揘 bond heterolysis to yield [CuO]⁺ complexes. For both strategies, the course of the reactions depended on the nature of the supporting bidentate N-donor ligand, and indirect evidence in support of the sought-after [CuO]⁺ intermediates was obtained in some instances.