Crystal chemistry of Te(IV) fluorinated compounds

Two new types of oxyfluorotellurates(IV): ScTeO3F and InTeO3F

“…In conclusion, these three structure types differ in the manner of connection of the M(O,F) 6 octahedra and in the respective O/F distribution in these octahedra, but they have an interesting common feature: in the MTeO 3 F (M = Fe, Cr and Ga) type, in ScTeO 3 F and to a first approximation in InTeO 3 F, the fluoride anions are not directly bonded to the tellurium cations, which are threefold coordinated by O atoms only. This feature draws these compounds closer to Te oxides than to the Te fluorides or oxyfluorides described previously, the latter phases being characterized by four-or fivefold coordination (Guillet et al, 1999(Guillet et al, , 2001Ider et al, 1996Ider et al, , 1999. This may also explain the unusually high thermal and chemical stability of these phases compared with the main oxyfluorotellurates(IV) already known.…”

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

“…The lone-pairs E of the Te IV atoms are stereochemically active and are arranged oppositely to each other. Like in many other tellurites(IV) [20] or Te(IV) fluorinated compounds [21], the lone-pairs point towards the cavities of the structure, in this case to the inter-sheet spaces. Two neighbouring layers are connected perpendicular to each other only by weak F · · · OH interactions at a distance of 2.82 Å (Fig.…”

The low-temperature barium fluoridozirconate variety α-BaZr2F10

“…Compounds with the general formula MM 0 2 F 10 are uncommon, but BaTe 2 F 10 (Laval et al, 1996) can also be compared with -BaZr 2 F 10 ; in a study devoted to the crystal chemistry of fluoridotellurates and oxyfluoridotellurates(IV) (Guillet et al, 2001), it was shown that the anionic polyhedra of Te 4+ are remarkably similar to the homologous polyhedra of Zr 4+ , U 4+ and Th 4+ , which are among the biggest tetravalent cations, with Te 4+ shifted off centre of its anionic polyhedra under the influence of its stereochemically active E lone pair. Indeed, this lone pair repels some of the anions of the Te 4+ coordination sphere, resulting in four or five F À anions being strongly bonded (Te-F = 1.8-2.2 Å ) and three or four F À anions at longer distances (Te-F= 2.5-3.5 Å ).…”