Concerted and Stepwise Proton-Coupled Electron Transfers in Aquo/Hydroxo Complex Couples in Water: Oxidative Electrochemistry of [OsII(bpy)2(py)(OH2)]2+
Concerted and Stepwise Proton-Coupled Electron Transfers in Aquo/Hydroxo Complex Couples in Water: Oxidative Electrochemistry of [OsII(bpy)2(py)(OH2)]2+
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DOI：
10.1002/cphc.200800361
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发表时间：
2009-01-12
期刊：
影响因子：
2.9
通讯作者：
Teillout, Anne-Lucie
中科院分区：
文献类型：
--
作者：
Costentin, Cyrille;Robert, Marc;Teillout, Anne-Lucie
过渡金属（II）水配合物的连续氧化（（MOH 2）-O-II至（MOH）-O-III）是其中质子耦合电子转移反应极为常见的领域。这些PCET反应的机制-协调或逐步-是一个重要的问题，在理解和设计的自然或人工系统催化水的四电子氧化形成双氧。协调的质子耦合电子转移从对水金属（II）的氢氧化金属（III）的配合物需要一个质子接受基团的pK值之间的水配合物的紧密接近。否则，涉及高能量中间体的逐步电子-质子或质子-电子途径如下。以水为质子受体或质子供体的质子-电子协同路径效率低下。循环伏安法的标题配合物在缓冲水溶液中，并重新检查以前的结果，为一些复杂的连接到电极表面上，用于建立这些结论，这提供了一个起点上的路线，以更高程度的氧化，如那些参与催化水氧化。
Successive oxidation of transition metal(II) aqua complexes ((MOH2)-O-II to (MOH)-O-III) is a domain in which proton-coupled electron transfer reactions are extremely common. The mechanism of these PCET reactions-concerted or stepwise-is an important issue in the understanding and design of natural or artificial Systems catalyzing the formation of dioxygen by four-electron oxidation of water. Concerted proton-coupled electron transfer from on aqua metal(II) to a hydroxo metal(III) complex requires the close proximity of a proton-accepting group with a pK value between those of the aqua complexes. Otherwise, stepwise electron-proton or proton-electron pathways involving high-energy intermediates are followed. Concerted proton-electron pathways involving water as proton-acceptor or proton-donor group are inefficient. Cyclic voltammetry of the title complex in buffered aqueous solution and re-examination of previous results for the some complex attached to on electrode surface are used to establish these conclusions, which provide a starting point on the route to higher degrees of oxidation, such as those involved in the catalysis of water oxidation.