Theory of Chemical Bonds in Metalloenzymes XVII. Symmetry Breaking in Manganese Cluster Structures and Chameleonic Mechanisms for the O-O Bond Formation of Water Splitting Reaction
Theory of Chemical Bonds in Metalloenzymes XVII. Symmetry Breaking in Manganese Cluster Structures and Chameleonic Mechanisms for the O-O Bond Formation of Water Splitting Reaction
复制标题
金属酶中的化学键理论 XVII。
DOI：
10.1002/qua.23255
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发表时间：
2012
影响因子：
2.2
通讯作者：
Toru Saito
中科院分区：
文献类型：
--
作者：
Tamura;K.;Ohashi;Y.;Tsubota;T.;Takeuchi;D.;Hirabayashi;T.;Yaguchi,M.,Matsuyama;M.;Sekine;T. and Miyashita;Y.;中村亮介;Toru Saito
锰氧化物的簇结构中的对称性破坏的Ca（II）离子的掺杂检查有关的水裂解反应的变色龙机制。轨道和自旋相关图已被描绘，以澄清反应的单电子转移和电子对转移机制。应用自旋极化的分子轨道模型研究了多中心钙锰氧化物及相关体系催化氧-氧（O-O）键形成和氧析出的反应机理与磁耦合模式之间的对应关系.本UB 3LYP计算，然后自然轨道分析已被执行，以阐明关键中间体的电子结构和过渡态结构的O-O键形成。结果表明，反应通过连续的类二自由基机制进行，而没有离散的自由基碎片和/或由纯低自旋单重态的Ca（II）的对称性破缺引起的电子对转移机制。计算结果分别与低自旋态和高自旋态O-O键形成的局域单重态和三重态双自由基耦合机制相一致。因此，在析氧复合物中的磁（交换）耦合模式与可溶性甲烷单加氧酶的情况下的局部单线态和三线态双自由基机制直接相关。© 2011 Wiley Periodicals，Inc.国际量子化学杂志，2012年
Symmetry breaking in cluster structures of manganese oxides by doping of Ca(II) ion is examined in relation to chameleonic mechanisms of water splitting reaction. The orbital and spin correlation diagrams have been depicted to clarify one‐electron transfer and electron‐pair transfer mechanisms for the reaction. The spin‐polarized molecular orbital models have been applied to elucidate correspondence between magnetic‐coupling mode and reaction mechanism of the oxygen–oxygen (OO) bond formation and oxygen evolution catalyzed by multicenter Ca(II) manganese oxides and related systems. The present UB3LYP calculations followed by the natural orbital analyses have been performed to elucidate electronic structures of the key intermediates and the transition state structure for the OO bond formation. The results indicate that the reaction proceeds through the continuous diradicaloid mechanism without discreet free radical fragments and/or electron‐pair transfer mechanism induced by symmetry breaking with Ca(II) in the pure low‐spin singlet state. The computational results are compatible with local singlet and triplet diradical‐coupling mechanisms for the OO bond formation in the low‐ and high‐spin states, respectively. Thus, magnetic (exchange) coupling modes in the oxygen evolution complex are directly related to the local singlet and triplet diradical mechanisms as in the case of soluble methane monooxygenase. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2012