| Popis: |
A novel anion derived from the Anderson structure has been obtained in aqueous acid solution by condensation of three pairs of edge-sharing molybdenum octahedra around a central arsenite. This association forms a hexanuclear ring of Mo(V) with three external sulphate groups bridging the binuclear molybdenum units. This compound crystallizes in the presence of alkaline ions and its orthorhombic structure was solved by single crystal X-ray diffraction [ Cmca , a =24.3189(3) A, b =12.4454(1) A, c =26.9211(3) A, V =8 147,9 A 3 ] from 4 277 unique reflections [ I ≥2 σ ( I )], R 1 =0.0471 and w R 2 =0.1429. The solid is a three-dimensional network built up from cluster anions strongly connected to alkaline ions via ionic links. This soluble compound, presenting labile peripheral sulphates, is predisposed for exchanges to build new anions. © 2000 Academie des sciences / Editions scientifiques et medicales Elsevier SAS polyoxometalate / sulphate / reduced cluster / arsenite / molybdenum |
