Structure and redox properties of a novel decavanadium cluster [(V=O)(10)(mu(2)-O)(9)(mu(3)-O)(3)(C5H7O2)(6)] in dichloromethane

A novel decavanadium cluster [(V=O)(10)(mu (2)-O)(3)(C-5-O)(3)(C5H7O2)(6)] bearing ten oxovanadium(V) centers linked with bridging oxygen atoms was pr epared. In contrast to the well known decavanadate ion V10O286-, the molecu le was soluble in organic solvents such as dichloromethane and 1,1,2,2-tetr achloroethane due to the peripheral acetylacetone ligands. X-ray crystallog raphic analysis revealed a molecular Framework formed by nine square-pyrami dal VO5 polyhedra surrounding one VO4 tetrahedron linked through the corner s. The molecule consists of approximate three-fold rotational symmetry, all owing the classification of ten vanadium atoms into four chemically equival ent categories. The unique metal core geometry persists in solution, which was demonstrated by the four peaks in the V-51-NMR spectrum. However, the f our types of vanadium atom could not be distinguished by electrochemical me asurements; 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). (C) 2001 Elsevier Science B.V. All rights reserved.