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

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 C_3i) arising from the conversion mediated by Cs⁺ counter-ions.. Authors: Deblonde, Gauthier [Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)] (ORCID:0000000208258714); Colliard, Ian [Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)]. DOE Contract: AC52-07NA27344. Subjects: 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; counter-ion conversion; crystal structure; isopolytungstates; polyoxidometalates; toroidal structures