Rich Structural Chemistry in Scandium Selenium/Tellurium Oxides: Mixed-Valent Selenite-Selenates, Sc2(SeO3)2(SeO4) and Sc2(TeO3)(SeO3)(SeO4), and Ternary Tellurite, Sc2(TeO3)3

Both single crystals and pure bulk phases of three new scandium selenium/tellurium oxides, Sc-2(SeO3)(2)(SeO4), Sc-2(TeO3)-(SeO3)(SeO4), and Sc-2(TeO3)(3), have been synthesized through hydrothermal and solid-state reactions. X-ray diffractions were used to determine the structures and confirm the phase purities of the reported materials. Isostructural Sc-2(SeO3)(2)(SeO4) and Sc-2(TeO3)(SeO3)(SeO4) reveal three-dimensional frameworks with Sc02 pentagonal bipyramids, SeO3 (and TeO3) trigonal pyramids, and SeO4 tetrahedra. A novel ternary scandium tellurite, Sc-2(TeO3)(3), also shows a three-dimensional framework that is composed of ScO6 octahedra, ScO7-capped octahedra, and TeO3 trigonal pyramids. All three materials accommodate local asymmetric coordination moieties owing to the lone pairs on Se4+ and Te4+ cations. The effect of coordination environments of constituent cations on the frameworks, dimensionalities, and centricities of products is discussed. Thorough characterizations including elemental analyses, infrared and UV-vis diffuse reflectance spectroscopies, thermal analyses, and dipole moment calculations for the reported materials are reported. Crystal data: Sc-2(SeO3)(2)(SeO4), monoclinic, space group P2(1)/c (No. 14), a = 6.5294(2) angstrom, b = 10.8557(4) angstrom, c = 12.6281(6) angstrom, beta = 103.543(3)degrees, V = 870.21(6) angstrom(3), and Z = 4; Sc-2(TeO3)(SeO3)(SeO4), monoclinic, space group P2(1)/c (No. 14), a = 6.5345(12) angstrom, b = 10.970(2) angstrom, c = 12.559(2) angstrom, beta = 102.699(10)degrees, V = 878.3(6) angstrom(3), and Z = 4; Sc-2(TeO3)(3), monoclinic, space group P2(1)/n (No. 14), a = 5.2345(3) angstrom, b = 24.3958(15) angstrom, c = 6.8636(4) angstrom, beta = 106.948(2)degrees, V = 838.42(9) angstrom(3), and Z = 4.