Characterization of the Fe V =O Complex in the Pathway of Water Oxidation
Characterization of the Fe V =O Complex in the Pathway of Water Oxidation
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DOI：
10.1002/ange.202003278
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发表时间：
2020-05
影响因子：
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通讯作者：
R. Ezhov;A. K. Ravari;Y. Pushkar
中科院分区：
文献类型：
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作者：
R. Ezhov;A. K. Ravari;Y. Pushkar
高价FeV=O物种涉及有机底物的多种氧化反应，以及对人工光合作用至关重要的催化水氧化反应。光谱表征的FeV物种是极其罕见的，到目前为止，这些物种是由Fe络合物与过氧酸或过氧化氢氧化产生的：这些反应需要断裂O−O键以形成FeV=O片段。在水氧化反应中引发O−O键形成的关键FeV=O物种仍然没有被检测到，可能是因为它们具有很高的反应活性。在这里，我们实现了对催化水氧化生成的六配位[Fev=O，(OH)(Pytacn)]2+(Pytacn=1‐(2′‐pyridylmethyl)‐4，7‐dimethyl‐1，4，7‐triazacyclononane)(2)]的冷冻猝灭捕获。X射线吸收光谱(XAS)证实了FeV的氧化状态和在≈1.60 ä处FeV=O键的存在。EPR和DFT相结合的方法表明，2含有As=3/2FeV中心。2是第一个光谱表征的高自旋氧-FeV络合物，并构成了催化水氧化反应的FeV=O(OH)物种的范例。
Hypervalent FeV=O species are implicated in a multitude of oxidative reactions of organic substrates, as well as in catalytic water oxidation, a reaction crucial for artificial photosynthesis. Spectroscopically characterized FeVspecies are exceedingly rare and, so far, were produced by the oxidation of Fe complexes with peroxy acids or H2O2: reactions that entail breaking of the O−O bond to form a FeV=O fragment. The key FeV=O species proposed to initiate the O−O bond formation in water oxidation reactions remained undetected, presumably due to their high reactivity. Here, we achieved freeze quench trapping of six coordinated [FeV=O,(OH)(Pytacn)]2+(Pytacn=1‐(2′‐pyridylmethyl)‐4,7‐dimethyl‐1,4,7‐triazacyclononane) (2) generated during catalytic water oxidation. X‐ray absorption spectroscopy (XAS) confirmed the FeVoxidation state and the presence of a FeV=O bond at ≈1.60 Å. Combined EPR and DFT methods indicate that2contains aS=3/2 FeVcenter.2is the first spectroscopically characterized high spin oxo‐FeVcomplex and constitutes a paradigmatic example of the FeV=O(OH) species proposed to be responsible for catalytic water oxidation reactions.