Ferromagnetic Coupling in a Mixed‐Valence Hexavanadate Core: Quantum‐Chemical Forecast

The electronic structure and magnetic properties of the recently synthesized VIV/VV mixed‐valence alkoxo‐polyoxovanadate comprising a hexanuclear vanadium core with four unpaired electrons have been studied within the DFT framework. The results of calculations suggest that the d electrons are completely trapped within the hexavanadate core, in agreement with the experimental observations. The exchange coupling constants computed using the broken symmetry formalism appeared to be of a ferromagnetic nature. Such interactions are very rare in oxovanadium complexes and are a consequence of a specific core geometry imposed by the polyoxometalate architecture. It has been shown that the earlier proposed intramolecular electron transfer cannot change the ground spin‐state multiplicity irrespective of the sign of the exchange parameters.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)