MnO Model of the S Intermediate of the Oxygen-Evolving Complex: Effect of the Dianionic Disiloxide Ligand

Overview

Journal Inorg Chem

Specialty Chemistry

Date 2022 Jul 13

PMID 35829634

Authors

Angela A Shiau

Heui Beom Lee

Paul H Oyala

Theodor Agapie

Affiliations

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Abstract

Synthetic complexes provide useful models to study the interplay between the structure and spectroscopy of the different S-state intermediates of the oxygen-evolving complex (OEC) of photosystem II (PSII). Complexes containing the Mn core corresponding to the S 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 MnO 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 MnMn/Mn redox couple by up to ∼760 mV, improving stability. The = 3 spin ground state of the siloxide-ligated MnO complex matches the acetate and amidate variants, in corroboration with the Mn assignment of the S state of the OEC.

Citing Articles

Coordination Number in High-Spin-Low-Spin Equilibrium in Cluster Models of the S State of the Oxygen Evolving Complex.

Shiau A, Lee H, Oyala P, Agapie T J Am Chem Soc. 2023; 145(27):14592-14598.

PMID: 37366634 PMC: 10575483. DOI: 10.1021/jacs.3c04464.

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