biostudies-literatureHenthorn JTDeutsche ForschungsgemeinschaftAlexander von Humboldt-StiftungMax-Planck-Gesellschaft328-333https://www.ebi.ac.uk/biostudies/studies/S-EPMC8898764biostudies-literatureUnknown14(3)The electronic structure and ground spin states, S, observed for mixed-valent iron-sulfur dimers (Fe^II-Fe^III) are typically determined by the Heisenberg exchange interaction, J, that couples the magnetic interaction of the two metal centres either ferromagnetically (J > 0, S = 9/2) or antiferromagnetically (J < 0, S = 1/2). In the case of antiferromagnetically coupled iron centres, stabilization of the high-spin S = 9/2 ground state is also feasible through a Heisenberg double-exchange interaction, B, which lifts the degeneracy of the Heisenberg spin states. This theorem also predicts intermediate spin states for mixed-valent dimers, but those have so far remained elusive. Herein, we describe the structural, electron paramagnetic resonance and Mössbauer spectroscopic,Nature chemistryStabilization of intermediate spin states in mixed-valent diiron dichalcogenide complexes.PMC88987641877/1-2DeBeer SHenthorn JTCutsail GEWeyhermuller TfalseStabilization of intermediate spin states in mixed-valent diiron dichalcogenide complexes.The electronic structure and ground spin states, S, observed for mixed-valent iron-sulfur dimers (Fe^II-Fe^III) are typically determined by the Heisenberg exchange interaction, J, that couples the magnetic interaction of the two metal centres either ferromagnetically (J > 0, S = 9/2) or antiferromagnetically (J < 0, S = 1/2). In the case of antiferromagnetically coupled iron centres, stabilization of the high-spin S = 9/2 ground state is also feasible through a Heisenberg double-exchange interaction, B, which lifts the degeneracy of the Heisenberg spin states. This theorem also predicts intermediate spin states for mixed-valent dimers, but those have so far remained elusive. Herein, we describe the structural, electron paramagnetic resonance and Mössbauer spectroscopic,2022-01-01T00:00:00Z2022 Mar2026-05-31T08:53:39.914Z2026-04-08T08:12:41.172ZS-EPMC88987643505861010.1038/s41557-021-00853-5