Synthesis and structural characterization of a hydrated sodium–caesium tetracosatungstate(VI), Na5Cs19[W24O84]·21H2O

Abstract

Crystal formation of pentasodium nonadecacesium tetracosatungstate(VI) heneikosahydrate, Na5Cs19[W24O84]·21H2O, was successfully achieved by the conversion of [H2W12O42]10− through the addition of excess Cs+. The crystal structure comprising the toroidal isopolyoxidometalate is presented, as well as its Raman spectrum. Na5Cs19(H2O)21W24O84 crystallizes in the rhombohedral space group R\overline{3} with an obverse centering. The title compound represents the addition of a new member to the isopolytungstate family with mixed alkali counter-ions and contains rarely observed five-coordinate tungsten(VI) atoms in the [W24O84]24− anion (site symmetry C3i) arising from the conversion mediated by Cs+ counter-ions.

Keywords

• crystal structure
• polyoxidometalates
• isopolytungstates
• toroidal structures
• counter-ion conversion.