Note: Crystal Structure, Vibrational Spectrum and Thermal Behavior of the Ammonium Hexathiohypodiphosphate Dihydrate, (NH4)4P2S6 · 2H2O

Single crystals of (NH4)4P2S6 ・ 2H2O could be obtained and the crystal structure determined (monoclinic, P21/c with a = 6.931(1), b = 12.730(2), c = 17.446(2) Å , β = 96.87(1)°, V = 1528.2(4) Å3, Z = 4). The NH4 +, and [P2S6]4− ions and the water molecules are involved in an extended hydrogenbonding network. The FT-Raman and FT-IR spectra have been recorded and the observed vibrational frequencies assigned to tetrahedral NH4 + and [P2S6]4− (D3d) ions as well as to H2O molecules. The thermogravimetric analysis has shown that (NH4)4P2S6 · 2H2O starts to decompose at around 60 °C (up to 170 °C), but no distinct intermediates could be observed.