X-ray single crystal, thermal analysis and vibrational study of (NH4)2(SO4)0.92H(AsO4)0.08⋅Te(OH)6

The crystal structure of (NH4)2(SO4)0.92H(AsO4)0.08⋅Te(OH)6 [NSAsTe] crystallizes in the monoclinic system P21/c with the following parameters: a = 11.382(5) Å, b = 6.615(5) Å, c = 13.707(5) Å, β = 106.731(5)° and Z = 4. The structure is formed by a set of anions ( TeO 6 - 6 , S O 4 2 - and HAs O 4 2 - ) and NH4+ groups connected by two types of hydrogen bonds OH⋯O and NH⋯O which make the building of the crystal. The differential scanning calorimetry (DSC) analysis has shown three-phase transitions before the decomposition at 399 K, 466 K and 471 K. The thermal analyses (DTA) and (TG) of the title compound has proven that the decomposition of this material starts at a temperature equal to 475 K. The Raman spectroscopy at various temperatures, it has confirmed the presence of the phase transitions shown in DSC and DTA. The vibrational study at room temperature shows the presence and the independence of anionic groups, ammonium groups and gives more importance to the strong hydrogen bonds.