Detection and mechanistic relevance of transient ligand radicals formed during [Ru(bPY)2(OH2)]2O4+-catalyzed water oxidation
Detection and mechanistic relevance of transient ligand radicals formed during [Ru(bPY)2(OH2)]2O4+-catalyzed water oxidation
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DOI：
10.1021/ja077276s
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发表时间：
2008-01-23
影响因子：
15
通讯作者：
Hurst, James K.
中科院分区：
文献类型：
--
作者：
Cape, Jonathan L.;Hurst, James K.
解释水氧化钌二亚胺络合物的反应性的机制建议经常引起通过溶剂与聚吡啶配体的反应形成的共价水合或假碱中间体的参与。探测这些中间体已被证明是困难的，因为可检测的活性物质的浓度在常用的实验条件下非常低。然而，我们最近发现，这些瞬变积累在中性pH值的光催化氧化系统中。在这项工作中，我们表明，这些瞬态物种的反应速率与催化活性，因此，他们满足最低动力学标准是真正的反应中间体。
Mechanistic proposals to account for the reactivity of water-oxidizing ruthenium diimine complexes have often invoked participation of covalently hydrated or pseudobase intermediates formed by reaction of solvent with the polypyridyl ligands. Probing for these intermediates has proven difficult because the concentrations of detectable reactive species are very low under commonly used experimental conditions. However, we have recently found that these transients accumulate in photocatalytic oxidation systems at neutral pH. In this work, we show that the reaction rates of these transient species correlate with catalytic activity and, therefore, that they meet minimal kinetic criteria to be true reaction intermediates.