Single crystal growth and crystal structure of HgTeO 2FOH—a layered fluorohydroxooxotellurate(IV) stabilized by weak F⋯OH interactions

Abstract

Light-yellow crystals of HgTeO 2FOH were obtained under hydrothermal conditions by reacting stoichiometric amounts of TeO 2 and HgO in diluted HF, or alternatively, by dissolution of TeO 2 and Hg(NO 3) 2·H 2O in 15 wt.% HF and subsequent slow evaporation of the solution. The crystal structure (space group Pca2 1 (#29), Z = 4, a = 7.8960(7), b = 6.7845(6), c = 6.8641(6) Å, 1044 structure factors, 56 parameters, R[ F 2 >2 σ( F 2)] = 0.0186, Goof = 1.007) was determined from a single crystal diffractometer data set and is made up from distorted [Hg IIO 4F 2(OH)] polyhedra and (Te IVO 2F(OH)) 2− anions. These main building units form a layered assembly parallel to (0 1 0). Upon heating, HgTeO 2FOH decomposes above 300 °C in a two-step mechanism under formation of the mixed-valent α-Hg II 2Te IV/VI 2O 7 and traces of Hg II 2Te VIO 5 in the first step, and of formation of TeO 2 in the second step.