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M. Weil, B. Stöger, C. Larvor, I. Raih, C. Gierl-Mayer:
"The hydrous sodium oxotellurates(VI) Na[TeO(OH)5)], Na2[TeO2(OH)4)], Na4[Te2O6(OH)4)](H2O)6, and a third polymorph of anhydrous Na2TeO4";
Zeitschrift für Anorganische und Allgemeine Chemie, 643 (2017), 23; 1888 - 1897.

Single crystals of the compounds Na[TeO(OH)5] (I), Na2[TeO2(OH)4] (II), Na4[Te2O6(OH)4](H2O)6 (III), and of a third polymorph (denoted as γ-) of anhydrous Na2[TeO4] (IV) were obtained from aqueous solutions (I and III), under hydrothermal conditions (II) and from a NaNO3 melt (IV), respectively. Structure determinations on basis of single-crystal X-ray diffraction data revealed a lowering of the previously reported cubic symmetry and the presence of a fourfold superstructure for (I), whereas (II) - (IV) crystallize in new structure types. Common features of the four sodium oxotellurate(VI) structures are [TeO6] octahedra. They are isolated in the structures of (I) and (II), condensed into a dinuclear [Te2O6(OH)4]4- anion in (III) and into an infinite zigzag 1∞[TeO4/2O2/1]2- chain in (IV). The coordination numbers of the sodium cations in the four structures range from four to seven. The temperature behaviour of (I), (II), and (III) was investigated by thermal analysis measurements (thermogravimetry, differential scanning calorimetry, differential thermal analysis) and in situ powder X-ray diffraction, revealing multistep decomposition sequences for the three compounds.

http://dx.doi.org/10.1002/zaac.201700245