Ab Initio Modeling of the Effect of Oxidation Coupled with HnO Deprotonation on Carboxylate Ligands in Mn/Ca Clusters

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• 作者：Wooi Yee Chuah ; Rob Stranger ; Ron J. Pace ; Elmars Krausz ; Terry J. Frankcombe
• 刊名：Journal of Physical Chemistry B
• 出版年：2014
• 出版时间：April 3, 2014
• 年：2014
• 卷：118
• 期：13
• 页码：3553-3558
• 全文大小：294K
• 年卷期：v.118,no.13(April 3, 2014)
• ISSN：1520-5207

文摘

Oxidation of some manganese complexes containing both carboxylate and water/hydroxo ligands does not result in changes to the carboxylate stretching frequencies. The water oxidizing complex of photosystem II is one motivating example. On the basis of electronic structure theory calculations, we here suggest that the deprotonation of water or hydroxo ligands minimizes changes in the vibrational frequencies of coligating carboxylates, rendering the carboxylate modes 鈥渋nvisible鈥?in FTIR difference spectroscopy. This deprotonation of water/hydroxo ligands was also found to balance the redox potentials of the Mn(II)/Mn(III) and Mn(III)/Mn(IV) couples, allowing the possibility for successive manganese oxidations at a relatively constant redox potential.