Southern Laboratories-208 A, Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, 208016, India.
Molecular Inorganic Chemistry, Stratingh Institute for Chemistry, University of Groningen, 9747 AG, Groningen, The Netherlands.
Angew Chem Int Ed Engl. 2022 Oct 10;61(41):e202211345. doi: 10.1002/anie.202211345. Epub 2022 Sep 2.
Cytochrome P450s and Galactose Oxidases exploit redox active ligands to form reactive high valent intermediates for oxidation reactions. This strategy works well for the late 3d metals where accessing high valent states is rather challenging. Herein, we report the oxidation of Ni (salen) (salen=N,N'-bis(3,5-di-tert-butyl-salicylidene)-1,2-cyclohexane-(1R,2R)-diamine) with mCPBA (meta-chloroperoxybenzoic acid) to form a fleeting Ni bisphenoxyl diradical species, in CH CN and CH Cl at -40 °C. Electrochemical and spectroscopic analyses using UV/Vis, EPR, and resonance Raman spectroscopies revealed oxidation events both on the ligand and the metal centre to yield a Ni bisphenoxyl diradical species. DFT calculations found the electronic structure of the ligand and the d-configuration of the metal center to be consistent with a Ni bisphenoxyl diradical species. This three electron oxidized species can perform hydrogen atom abstraction and oxygen atom transfer reactions.
细胞色素 P450s 和半乳糖氧化酶利用氧化还原活性配体形成反应性高价中间体，用于氧化反应。这种策略在后期 3d 金属中效果很好，因为很难进入高价态。在此，我们报告了 mCPBA（间氯过氧苯甲酸）与 Ni（salen）（salen=N，N'-双（3,5-二叔丁基水杨醛）-1,2-环己烷-（1R，2R）-二胺）在 CH3CN 和 CH2Cl 中-40 °C 下氧化生成瞬态 Ni 双酚氧自由基物种。使用 UV/Vis、EPR 和共振拉曼光谱进行的电化学和光谱分析表明，配体和金属中心都发生了氧化事件，生成了 Ni 双酚氧自由基物种。DFT 计算发现配体的电子结构和金属中心的 d 构型与 Ni 双酚氧自由基物种一致。这种三电子氧化物种可以进行氢原子提取和氧原子转移反应。
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