Single crystals of the cerium(IV) oxotellurate(IV) CeTe2O6

Orange-red, coffin-shaped single crystals of CeTe2O6 (monoclinic, P2(1)/n; a = 703.71(5), b = 1106.32(8), c = 735.24(5) pm, beta = 108.066(6)degrees, Z = 4) were obtained by the reaction of admixtures of cerium dioxide and te llurium dioxide (CeO2, TeO2; molar ratio 1: 2) in the presence of fluxing C sCl (750 degreesC, 4 d) in evacuated silica tubes. The crystal structure co ntains eightfold coordinated Ce4+ cations, which are surrounded by irregula r trigonal dodecahedra of oxygen atoms. The interconnection of these [CeO8] polyhedra occurs via two edges (O2-O2 ' and O3-O3 ') with equatorial orien tation relative to each other forming zigzag chains (1)(infinity){[CeO4/1O4 /2](8-)} which run parallel to [100] and ar-range as a hexagonal packing of rods. Both crystallographically different Te4+, cations exhibit trigonal n on-planar coordination figures (Psi (1) tetrahedra) with three oxygen atoms each as a result of the stereochemical activity of the nonbinding electron pairs ("lone pairs"). They also are responsible for the necessary cross-li nkage of the anionic (1)(infinity){[CeO6](8-)} chains. The isotypical relat ionship with Ce(SeO3)(2) therefore justifies the formulation Ce(TeO3)(2) fo r CeTe2O6.