PREPARATION AND PROPERTIES OF NEW POLYOXOVANADATES

Preet Mahalay, Khalil A. Abboud and George Christou

Department of Chemistry, University of Florida, Gainesville FL-32611-7200, USA

Metal oxides are widely used in industry as heterogeneous catalysis for oxidation processes. Iso- and mixed-metal polyoxometalates are molecular species that can be considered soluble fragments of the metal-oxide lattice. Interest in the field of polyoxometalates is currently growing because of its applications in catalysis, zeolites, materials with striking electronic and magnetic properties, biological systems and sensors. Most polyoxovanadates have been synthesized from meta and orthovanadates, (Cat)VO₃ or (Cat)₃VO₄ (Cat⁺  = NH₄⁺, K⁺ or Na⁺), which have infinite chains of corner-sharing VO₄ tetrahedra, under acidic aqueous conditions; the first such product  was the decavanadate cluster [V₁₀O₂₈]^6-. We will describe new types of synthetic schemes to various polyoxovanadates, highlighting their structural differences to the other reported clusters as well as the bulk V₂O₅ lattice. We will also discuss the data obtained from ⁵¹V- and ¹⁷O- NMR spectroscopy, cyclic voltammetry and EPR spectroscopy.