Syntheses and structural characterization of new mixed-valent tellurium oxides, A<inf>4</inf>[Te<inf>5</inf>⁶⁺Te<inf>3</inf>⁴⁺]O²³ (A = Rb and K)

Two new isostructural mixed-valent tellurium oxides, A4[Te 56+Te34+]O23 [A = Rb (1) and K (2)], have been synthesized by solid-state reactions and characterized by X-ray diffraction and infrared spectroscopy. Compound 1 could be prepared by hydrothermal reaction as well. These compounds, as determined from the single-crystal X-ray structure of 1, consist of corrugated [Te6O 23] layers, built from corner-connected TeO6 octahedra and TeO5 square pyramids. These layers are connected to one another by tetravalent telluriums, having square-pyramidal and disphenoid geometries. Both compounds crystallize in the orthorhombic space group Pna21 (33) with Z = 4 and have the following unit cell parameters: For 1, a = 19.793(4), b = 14.664(4), and c = 7.292(4) Å. For 2, a = 19.573(3), b = 14.448(2), and c = 7.273(8) Å. © 2005 American Chemical Society.