Syntheses and structural characterization of vanado-tellurites and vanadyl-selenites: SrVTeO<inf>5</inf>(OH), Cd<inf>2</inf>V<inf>2</inf>Te<inf>2</inf>O<inf>11</inf>, Ca<inf>3</inf>VSe<inf>4</inf>O<inf>13</inf>·H<inf>2</inf>O and Ba<inf>2</inf>VSe<inf>3</inf>O<inf>10</inf>

Four new quaternary vanado-tellurites and vanadyl-selenites, namely, SrVTeO5(OH)(1), Cd2V2Te2O11(2), Ca3VSe4O13·H2O(3) and Ba2VSe3O10(4) have been synthesized and structurally characterized by single crystal X-ray diffraction. The oxidation state of vanadium is +5 in tellurites 1 and 2 and +4 in selenites 3 and 4. The structures of SrVTeO5(OH)(1) and Cd2V2Te2O11(2) compounds consist of (VTeO5(OH))2- and (V2Te2O11)4-anionic chains respectively, which are built from tetrahedral VO4 and disphenoidal TeO4 moieties. Similarly the structures of Ca3VSe4O13·H2O(3) and Ba2VSe3O10(4) respectively contain (VSe2O7)2- and (VSe3O10)4- anionic chains, which are made up of octahedral VO6 and pyramidal SeO3 units. Compounds 1 and 3 have been characterized by thermogravimetric and infrared spectroscopic methods. Compounds 1 and 2 are wide band gap semiconductors.