Structure and redox properties of a novel decavanadium cluster [(VO)10(μ2-O)9(μ3-O)3(C5H7O2)6] in dichloromethane

A novel decavanadium cluster [(VO)10(μ2-O)9(μ3-O)3(C5H7O2)6] bearing ten oxovanadium(V) centers linked with bridging oxygen atoms was prepared. In contrast to the well known decavanadate ion V10O286−, the molecule was soluble in organic solvents such as dichloromethane and 1,1,2,2-tetrachloroethane due to the peripheral acetylacetone ligands. X-ray crystallographic analysis revealed a molecular framework formed by nine square-pyramidal VO5 polyhedra surrounding one VO4 tetrahedron linked through the corners. The molecule consists of approximate three-fold rotational symmetry, allowing the classification of ten vanadium atoms into four chemically equivalent categories. The unique metal core geometry persists in solution, which was demonstrated by the four peaks in the 51V-NMR spectrum. However, the four types of vanadium atom could not be distinguished by electrochemical measurements; consequently, the molecule was a multielectron reservoir which showed a broad cathodic wave near 0.6 V vs. Ag | AgCl due to the reduction of the vanadium(V) centers to vanadium(IV).