Effect of the Mn Oxidation State on Single-Molecule-Magnet Properties: Mn^(III) vs Mn^(IV) in Biologically Inspired DyMn_3O_4 Cubanes

Inspired by the ferromagnetic coupling in the cubane model CaMn^(IV)_3O_4 of the oxygen-evolving complex of photosystem II, 3d–4f mixed-metal DyMn_3O_4 clusters were prepared for investigation of the magnetic properties. For comparison, YMn^(IV)_3O_4 and YMn^(IV)_2Mn^(III)O_4 clusters were investigated as well and showed ferromagnetic interactions, like the calcium analogue. DyMn^(IV)_3O_4 displays single-molecule-magnet properties, while the one-electron-reduced species (DyMn^(IV)_2Mn^(III)O_4) does not, despite the presence of a Mn^(III) center with higher spin and single-ion anisotropy