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Mnᴵⱽ₄O₄ Model of the S₃ Intermediate of the Oxygen-Evolving Complex: Effect of the Dianionic Disiloxide Ligand

Shiau, Angela A. and Lee, Heui Beom and Oyala, Paul H. and Agapie, Theodor (2022) Mnᴵⱽ₄O₄ Model of the S₃ Intermediate of the Oxygen-Evolving Complex: Effect of the Dianionic Disiloxide Ligand. Inorganic Chemistry . ISSN 0020-1669. doi:10.1021/acs.inorgchem.2c01612. (In Press)

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Synthetic complexes provide useful models to study the interplay between the structure and spectroscopy of the different Sn-state intermediates of the oxygen-evolving complex (OEC) of photosystem II (PSII). Complexes containing the Mnᴵⱽ₄ core corresponding to the S₃ state, the last observable intermediate prior to dioxygen formation, remain very rare. Toward the development of synthetic strategies to stabilize highly oxidized tetranuclear complexes, ligands with increased anion charge were pursued. Herein, we report the synthesis, electrochemistry, SQUID magnetometry, and electron paramagnetic resonance spectroscopy of a stable Mnᴵⱽ₄O₄ cuboidal complex supported by a disiloxide ligand. The substitution of an anionic acetate or amidate ligand with a dianionic disiloxide ligand shifts the reduction potential of the MnᴵᴵᴵMnᴵⱽ₃/Mnᴵⱽ₄ redox couple by up to ∼760 mV, improving stability. The S = 3 spin ground state of the siloxide-ligated Mnᴵⱽ₄O₄ complex matches the acetate and amidate variants, in corroboration with the MnIV4 assignment of the S₃ state of the OEC.

Item Type:Article
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URLURL TypeDescription
Shiau, Angela A.0000-0003-4395-9847
Lee, Heui Beom0000-0002-9550-2649
Oyala, Paul H.0000-0002-8761-4667
Agapie, Theodor0000-0002-9692-7614
Additional Information:© 2022 American Chemical Society. Published online 13 July 2022. This article is part of the Discrete Coordination Cages and Metal Clusters special issue. This research was supported by the NIH (Grant R01-GM102687B). We thank the Beckman Institute at Caltech and the Dow Next Generation Educator Fund for instrumentation support. Magnetic data were acquired on a SQUID supported by NSF Grant MRI-1625776. We thank Dr. Michael Takase and Lawrence Henling for assistance with X-ray crystallography and Dr. Ignacio Martini with SQUID magnetometry. The authors declare no competing financial interest. Accession Codes. CCDC 2171723 and 2171724 contain the supplementary crystallographic data for this paper
Funding AgencyGrant Number
Caltech Beckman InstituteUNSPECIFIED
Dow Next Generation Educator FundUNSPECIFIED
Subject Keywords:Cluster chemistry, Ligands, Quantum mechanics, Redox reactions, Transition metals
Record Number:CaltechAUTHORS:20220714-369441000
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Official Citation:Mnᴵⱽ₄O₄ Model of the S₃ Intermediate of the Oxygen-Evolving Complex: Effect of the Dianionic Disiloxide Ligand Angela A. Shiau, Heui Beom Lee, Paul H. Oyala, and Theodor Agapie Inorganic Chemistry Article ASAP DOI: 10.1021/acs.inorgchem.2c01612
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:115556
Deposited By: George Porter
Deposited On:14 Jul 2022 23:08
Last Modified:14 Jul 2022 23:08

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