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MO: Fachverband Molekülphysik
MO 15: Spectroscopy of Metal Clusters
MO 15.5: Vortrag
Mittwoch, 13. März 2024, 15:45–16:00, HS 3042
Electronic state of a dioxidomanganese(V) and bis(mu-oxo) di-manganese oxide cluster revealed by XAS and XMCD — •O.S. Ablyasova1,2, E.B. Boydas3, M. Ugandi3, V. Zamudio-Bayer1, K. Hirsch1, M. Flach1,2, M. da Silva Santos1,2, M. Timm1, B. von Issendorff2, M. Römelt3, and J.T. Lau1,2 — 1HZB, Albert-Einstein-Straße 15, 12489 Berlin, Germany; — 2Universität Freiburg, Hermann-Herder-Straße 3, 79104 Freiburg, Germany — 3Humboldt Universität, Brook-Taylor-Straße 2, 12489 Berlin, Germany
The CaMn4O5 cluster’s electronic structure plays a crucial role in understanding dioxygen formation in the Kok cycle. The S4 state, responsible for O2 formation, is difficult to observe because of the millisecond time scale of the transition. Two main models for the S4 state feature different oxidation states of +4 and +5 of the manganese atom at the reaction site. We report on the characterization of cold cationic gas-phase manganese oxide complexes via XAS and XMCD. We identify oxidation and spin states by comparison with reference spectra of manganese compounds with known oxidation states, accompanied by multireference and density functional theory calculations. We demonstrate that cationic Mn(V)O2+ is only the second manganese oxo complex to exist in a high-spin state. Our most important result is the identification of a Mn2O3+ species with Mn(V) in a high-spin state. This is the first observation of the elusive Mn(V) high-spin state in a polymanganese oxido complex, which may have implications for the future study of CaMn4O5 complex structure.
Keywords: Photosystem II; Manganese oxide cluster; XAS; XMCD; Oxidation state