Effect of the Mn Oxidation State on Single-Molecule-Magnet Properties: Mn^III vs Mn^IV in Biologically Inspired DyMn₃O₄ Cubanes

Inspired by the ferromagnetic coupling in the cubane model CaMn^IV₃O₄ of the oxygen-evolving complex of photosystem II, 3d–4f mixed-metal DyMn₃O₄ clusters were prepared for investigation of the magnetic properties. For comparison, YMn^IV₃O₄ and YMn^IV₂Mn^IIIO₄ clusters were investigated as well and showed ferromagnetic interactions, like the calcium analogue. DyMn^IV₃O₄ displays single-molecule-magnet properties, while the one-electron-reduced species (DyMn^IV₂Mn^IIIO₄) does not, despite the presence of a Mn^III center with higher spin and single-ion anisotropy