Department of Chemistry and Nano Science, Center for Biomimetic Systems, Ewha Womans University, Seoul 03760, Korea.
Center for Catalytic Hydrocarbon Functionalizations, Institute for Basic Science (IBS), Daejeon 34141, Korea.
Nat Commun. 2017 Mar 24;8:14839. doi: 10.1038/ncomms14839.
Terminal cobalt(IV)-oxo (Co-O) species have been implicated as key intermediates in various cobalt-mediated oxidation reactions. Herein we report the photocatalytic generation of a mononuclear non-haem [(13-TMC)Co(O)] (2) by irradiating [Co(13-TMC)(CFSO)] (1) in the presence of [Ru(bpy)], NaSO, and water as an oxygen source. The intermediate 2 was also obtained by reacting 1 with an artificial oxidant (that is, iodosylbenzene) and characterized by various spectroscopic techniques. In particular, the resonance Raman spectrum of 2 reveals a diatomic Co-O vibration band at 770 cm, which provides the conclusive evidence for the presence of a terminal Co-O bond. In reactivity studies, 2 was shown to be a competent oxidant in an intermetal oxygen atom transfer, C-H bond activation and olefin epoxidation reactions. The present results lend strong credence to the intermediacy of Co-O species in cobalt-catalysed oxidation of organic substrates as well as in the catalytic oxidation of water that evolves molecular oxygen.
终端钴（IV）-氧（Co-O）物种被认为是各种钴介导的氧化反应中的关键中间体。在此，我们报告了在[Ru（bpy）]、NaSO 和水作为氧源的存在下，通过辐照[Co（13-TMC）（CFSO）]（1）来光催化生成单核非血红素[(13-TMC)Co（O）]（2）。中间体 2 也可以通过将 1 与人工氧化剂（即碘苯）反应获得，并通过各种光谱技术进行了表征。特别是，2 的共振拉曼光谱在 770 cm 处显示出一个二原子 Co-O 振动带，这为存在终端 Co-O 键提供了确凿的证据。在反应性研究中，2 被证明是金属间氧原子转移、C-H 键活化和烯烃环氧化反应中的有效氧化剂。目前的结果有力地证明了 Co-O 物种在钴催化氧化有机底物以及水的催化氧化生成分子氧中的中间体作用。
