Lee, Heui Beom and Shiau, Angela A. and Marchiori, David A. and Oyala, Paul H. and Yoo, Byung-Kuk and Kaiser, Jens T. and Rees, Douglas C. and Britt, R. David and Agapie, Theodor (2021) CaMn₃^(IV)O₄ Cubane Models of the Oxygen Evolving Complex: Spin Ground States S < 9/2 and the Effect of Oxo Protonation. Angewandte Chemie International Edition, 60 (32). pp. 17671-17679. ISSN 1433-7851. PMCID PMC8319083. doi:10.1002/anie.202105303. https://resolver.caltech.edu/CaltechAUTHORS:20210527-093456375
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Abstract
We report the single crystal XRD and MicroED structure, magnetic susceptibility, and EPR data of a series of CaMn₃^(IV)O₄ and YMn₃^(IV)O₄ complexes as structural and spectroscopic models of the cuboidal subunit of the oxygen-evolving complex (OEC). The effect of changes in heterometal identity, cluster geometry, and bridging oxo protonation on the spin-state structure was investigated. In contrast to previous computational models, we show that the spin ground state of CaMn₃^(IV)O₄ complexes and variants with protonated oxo moieties need not be S=9/2. Desymmetrization of the pseudo-C₃-symmetric Ca(Y)Mn₃^(IV)O₄ core leads to a lower S=5/2 spin ground state. The magnitude of the magnetic exchange coupling is attenuated upon oxo protonation, and an S=3/2 spin ground state is observed in CaMn₃^(IV)O₃(OH). Our studies complement the observation that the interconversion between the low-spin and high-spin forms of the S₂ state is pH-dependent, suggesting that the (de)protonation of bridging or terminal oxygen atoms in the OEC may be connected to spin-state changes.
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Alternate Title: | CaMn3IVO4 Cubane Models of the Oxygen Evolving Complex: Spin Ground States S < 9/2 and the Effect of Oxo Protonation | ||||||||||||||||||||
Additional Information: | © 2021 Wiley-VCH GmbH. Issue Online: 26 July 2021; Version of Record online: 01 July 2021; Accepted manuscript online: 26 May 2021; Manuscript received: 25 April 2021. This research was supported by the NIH (R01-GM102687B to T.A.), Dow Next Generation Educator (instrumentation), NSF-1531940 (Caltech EPR facility), the Division of Chemical Sciences, Geosciences, and Biosciences (R.D.B. grant DE-SC0007203) of the Office of Basic Energy Sciences of the U.S. Department of Energy. We thank Dr. Michael K. Takase and Mr. Lawrence M. Henling at Caltech for assistance with XRD; Dr. Ignacio B. Martini at UCLA for assistance with magnetometry (NSF, MRI-1625776). We thank Andrey Malyutin and Songye Chen for their support during the microED data collection conducted at the Caltech cryoEM facility, and the Beckman Institute at Caltech for their generous support of the cryoEM facility and the Molecular Observatory. The authors declare no conflict of interest. | ||||||||||||||||||||
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Subject Keywords: | electronic structure; magnetic susceptibility; model complexes; oxygen-evolving complex; spin states | ||||||||||||||||||||
Issue or Number: | 32 | ||||||||||||||||||||
PubMed Central ID: | PMC8319083 | ||||||||||||||||||||
DOI: | 10.1002/anie.202105303 | ||||||||||||||||||||
Record Number: | CaltechAUTHORS:20210527-093456375 | ||||||||||||||||||||
Persistent URL: | https://resolver.caltech.edu/CaltechAUTHORS:20210527-093456375 | ||||||||||||||||||||
Official Citation: | CaMn₃^(IV)O₄ Cubane Models of the Oxygen Evolving Complex: Spin Ground States S < 9/2 and the Effect of Oxo Protonation. H. B. Lee, A. A. Shiau, D. A. Marchiori, P. H. Oyala, B.-K. Yoo, J. T. Kaiser, D. C. Rees, R. D. Britt, T. Agapie, Angew. Chem. Int. Ed. 2021, 60, 17671; DOI: 10.1002/anie.202105303 | ||||||||||||||||||||
Usage Policy: | No commercial reproduction, distribution, display or performance rights in this work are provided. | ||||||||||||||||||||
ID Code: | 109270 | ||||||||||||||||||||
Collection: | CaltechAUTHORS | ||||||||||||||||||||
Deposited By: | George Porter | ||||||||||||||||||||
Deposited On: | 27 May 2021 22:08 | ||||||||||||||||||||
Last Modified: | 02 Aug 2021 20:20 |
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