화학공학소재연구정보센터
Inorganic Chemistry, Vol.49, No.24, 11627-11636, 2010
Syntheses and Crystal Structures of a Series of Alkaline Earth Vanadium Selenites and Tellurites
Six new novel alkaline-earth metal vanadium(V) or vanadium(IV) selenites and tellurites, namely, Sr-2(VO)(3)(SeO3)(5), Sr(V2O5)(TeO3), Sr-2(V2O5)(2)(TeO3)(2)(H2O), Ba-3(VO2)(2)(SeO3)(4), Ba-2(VO3)Te4O9(OH), and Ba2V2O5(Te2O6), have been prepared and structurally characterized by single crystal X-ray diffraction analyses. These compounds exhibit six different anionic structures ranging from zero-dimensional (OD) cluster to three-dimensional (3D) network. Sr-2(VO)(3)(SeO3)(5) features a 3D anionic framework composed of VO6 octahecra that are bridged by SeO3 polyhedra. The oxidation state of the vanadium cation is +4 because of the partial reduction of V2O5 by SeO2 at high temperature. Ba-3(VO2)(2)(SeO3)(4) features a 0D [(VO2)(SeO3)(2)](3-) anion. Sr(V2O5)(TeO3) displays a unique 1D vanadium(V) tellurite chain composed of V2O8 and V2O7 units connected by tellurite groups, forming 4- and 10-MRs, whereas Sr-2(V2O5)(2)(TeO3)(2)(H2O) exhibits a 2D layer consisting of [V4O14] tetramers interconnected by bridging TeO32--anions with the Sr2+ and water molecules located at the interlayer space. Ba-2(VO3)Te4O9(OH) exhibits a one-dimensional (1D) vanadium tellurite chain composed of a novel 1D [Te4O9(OH)](3-) chain further decorated by VO4 tetrahedra. Ba2V2O5(Te2O6) also features a 1D vanadium(V) tellurites chain in which neighboring VO4 tetrahedra are bridged by [Te2O6](4-) dimers. The existence of V4+ ions in Sr-2(VO)(3)(SeO3)(6) is also confirmed by magnetic measurements. The results of optical diffuse-reflectance spectrum measurements and electronic structure calculations based on density functional theory (DFT) methods indicate that all six compounds are wide-band gap semiconductors.