Hydrothermal synthesis and characterization of a new hydrated ammonium barium thioarsenate:: (NH4)BaAsS4•2H2O

A new alkaline-earth thioarsenate, (NH4)BaAsS4 . 2H(2)O, has been prepared using low-temperature solvothermal methods and characterized by single-crystal X-ray diffraction, both infrared and diffuse reflectance spectroscopies, and thermogravimetric analysis. The title compound crystallizes as large transparent yellow columns in the space group Pnma (no. 62) with a = 11.890(3), b = 6.929(3), c = 12.095(4) Angstrom, V = 996.5(6) Angstrom(3) and Z = 4 with R/R-w = 0.0230/0.0307. The compound exhibits a low-dimensional structure built from barium interactions with discrete tetrahedral Ass, units, creating a framework in which the barium, ammonium cations and water molecules reside. Thermal analysis indicates the loss of both water and ammonia at relatively low temperatures. (C) 2000 Editions scientifiques et medicales Elsevier SAS. All rights reserved.