Reactivity Differences of Trigonal Pyramidal Nonheme Iron(IV)‐Oxo and Iron(III)‐Oxo Complexes: Experiment and Theory
Reactivity Differences of Trigonal Pyramidal Nonheme Iron(IV)‐Oxo and Iron(III)‐Oxo Complexes: Experiment and Theory
复制标题
三角锥非血红素铁(IV)-Oxo 和铁(III)-Oxo 配合物的反应性差异：实验与理论
DOI：
10.1002/chem.202300271
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发表时间：
2023
期刊：
影响因子：
--
通讯作者：
de Visser, Sam P.
中科院分区：
文献类型：
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作者：
Cao, Yuanxin;Valdez‐Moreira, Juan A.;Hay, Sam;Smith, Jeremy M.;de Visser, Sam P.
高价金属氧物种在酶催化中发挥着关键作用，但它们的性质仍然知之甚少。在这项工作中，我们报告了对仿生铁（IV）-氧和铁（III）-氧配合物的综合实验和计算研究，这些配合物具有限制底物进入的紧密的第二配位球环境。该工作表明，第二配位球显着减慢了从甲苯中提取氢原子的步骤，并且动力学在底物中是零级的。然而，形成的铁(II)-羟基具有较低的还原电位，因此不能有利地进行 OH 反弹。然后溶液中的甲苯基自由基与替代反应伙伴进一步反应。相比之下，铁(IV)-氧物种主要通过 OH 回弹反应形成醇产物。我们的研究表明，金属的氧化态极大地影响底物的反应性和选择性，并且酶可能需要铁（IV）中心来催化 C−H 羟基化反应。
High‐valent metal‐oxo species play critical roles in enzymatic catalysis yet their properties are still poorly understood. In this work we report a combined experimental and computational study into biomimetic iron(IV)‐oxo and iron(III)‐oxo complexes with tight second‐coordination sphere environments that restrict substrate access. The work shows that the second‐coordination sphere slows the hydrogen atom abstraction step from toluene dramatically and the kinetics is zeroth order in substrate. However, the iron(II)‐hydroxo that is formed has a low reduction potential and hence cannot do OH rebound favorably. The tolyl radical in solution then reacts further with alternative reaction partners. By contrast, the iron(IV)‐oxo species reacts predominantly through OH rebound to form alcohol products. Our studies show that the oxidation state of the metal influences reactivities and selectivities with substrate dramatically and that enzymes will likely need an iron(IV) center to catalyze C−H hydroxylation reactions.