Synthesis and reactivity of a mononuclear non-haem cobalt(IV)-oxo complex.
Synthesis and reactivity of a mononuclear non-haem cobalt(IV)-oxo complex.
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DOI：
10.1038/ncomms14839
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发表时间：
2017-03-24
影响因子：
16.6
通讯作者：
Nam W
中科院分区：
文献类型：
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作者：
Wang B;Lee YM;Tcho WY;Tussupbayev S;Kim ST;Kim Y;Seo MS;Cho KB;Dede Y;Keegan BC;Ogura T;Kim SH;Ohta T;Baik MH;Ray K;Shearer J;Nam W
末端钴（IV）-氧代（CoIV-O）物质在各种钴介导的氧化反应中被认为是关键中间体。本文报道了在[RuII（bpy）3]2+、Na 2S 2 O 8和水作为氧源的存在下，通过照射[CoII（13-TMC）（CF 3SO 3）]+（1），光催化生成单核非血红素[（13-TMC）CoIV（O）]2+（2）。中间体2也是通过1与人工氧化剂（即碘酰苯）反应得到的，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−1处显示出双原子Co-O振动带，这为末端Co-O键的存在提供了确凿的证据。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。本研究结果提供了强有力的证据CoIV-O物种在钴催化氧化的有机底物，以及在水的催化氧化，演变成分子氧的中间。末端CoIV-氧代物种是各种钴介导的氧化反应中的关键中间体，但对其化学性质知之甚少。在这里，作者生成并分离出单核非血红素CoIV-O复合物，并分析其结构和对一系列催化转化的反应性。
Terminal cobalt(IV)–oxo (CoIV–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)CoIV(O)]2+ (2) by irradiating [CoII(13-TMC)(CF3SO3)]+ (1) in the presence of [RuII(bpy)3]2+, Na2S2O8, 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−1, 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 CoIV–O species in cobalt-catalysed oxidation of organic substrates as well as in the catalytic oxidation of water that evolves molecular oxygen. Terminal CoIV-oxo species are key intermediates in various cobalt-mediated oxidation reactions, but little is known about their chemical properties. Here the authors generate and isolate a mononuclear non-haem CoIV-O complex and analyse its structure and reactivity towards a range of catalytic transformations.