Single crystal growth and crystal structure of HgTeO2FOH-a layered fluorohydroxooxotellurate(IV) stabilized by weak F⋯OH interactions

Light-yellow crystals of HgTeO2FOH were obtained under hydrothermal conditions by reacting stoichiometric amounts of TeO2 and HgO in diluted HF, or alternatively, by dissolution of TeO2 and Hg(NO3)2·H2O in 15 wt.% HF and subsequent slow evaporation of the solution. The crystal structure (space group Pca21 (#29), Z = 4, a = 7.8960(7), b = 6.7845(6), c = 6.8641(6) Å, 1044 structure factors, 56 parameters, R[F2 >2σ(F2)] = 0.0186, Goof = 1.007) was determined from a single crystal diffractometer data set and is made up from distorted [HgIIO4F2(OH)] polyhedra and (TeIVO2F(OH))2− anions. These main building units form a layered assembly parallel to (0 1 0). Upon heating, HgTeO2FOH decomposes above 300 °C in a two-step mechanism under formation of the mixed-valent α-HgII2TeIV/VI2O7 and traces of HgII2TeVIO5 in the first step, and of formation of TeO2 in the second step.