Connecting Organometallic Ni(III) and Ni(IV): Reactions of Carbon-Centered Radicals with High-Valent Organonickel Complexes
Connecting Organometallic Ni(III) and Ni(IV): Reactions of Carbon-Centered Radicals with High-Valent Organonickel Complexes
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DOI：
10.1021/jacs.9b02411
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发表时间：
2019-06-05
影响因子：
15
通讯作者：
Sanford, Melanie S.
中科院分区：
文献类型：
--
作者：
Bour, James R.;Ferguson, Devin M.;Sanford, Melanie S.
本文描述了可分离的Ni-III和Ni-IV配合物通过与碳中心自由基（R中心点）反应的单电子相互转化。首先，模型Ni-III络合物被示出与烷基和芳基自由基反应以提供Ni-IV产物。初步的机理研究暗示了一个途径，涉及直接添加一个碳中心的自由基的镍-III中心。这直接类似于Ni-II络合物与R中心点的已知反应性，这是通常涉及催化的步骤。第二，Ni-IV-CH_3配合物与芳基和烷基通过S（H）_2-型机理反应生成C-C键。利用该途径能够在温和条件下形成具有挑战性的H3C-CF 3键。总体而言，这些调查表明，镍-II/III/IV序列可能是可行的氧化还原途径在高氧化态镍催化。
This paper describes the one-electron interconversions of isolable Ni-III and Ni-IV complexes through their reactions with carbon-centered radicals (R center dot). First, model Ni-III complexes are shown to react with alkyl and aryl radicals to afford Ni-IV products. Preliminary mechanistic studies implicate a pathway involving direct addition of a carbon-centered radical to the Ni-III center. This is directly analogous to the known reactivity of Ni-II complexes with R center dot, a step that is commonly implicated in catalysis. Second, a Ni-IV-CH3 complex is shown to react with aryl and alkyl radicals to afford C-C bonds via a proposed S(H)2-type mechanism. This pathway is leveraged to enable challenging H3C-CF3 bond formation under mild conditions. Overall, these investigations suggest that Ni-II/III/IV sequences may be viable redox pathways in high-oxidation-state nickel catalysis.