Synthese und Kristallstruktur des Barium -Kupfer-Tellurit-Tellurats BaCuTeO₃TeO₄ / Synthesis and Crystal Structure of the Barium Copper Tellurite-Tellurate BaCuTeO₃TeO₄

Abstract

Single crystals of BaCuTe03T e 0 4 have been prepared by crystallisation from melts. X-ray investigations lead to orthorhombic symmetry, space group C2v-Ama2, a = 5.4869(8), b = 15.412(1), c = 7.2066(4) A , Z = 4. This compound represents a new structure type, containing B aO 10, C u 0 5, T e 0 6 and T e 0 4 polyhedra. The lone pair (E ) of TeIV completes the TeIV0 4 polyhedron to a trigonal T e 0 4E bipyramid. The Te to E distance is estimated by calculations o f the Coulomb terms of lattice energy to 1.43 A .

Antiferromagnetic Order and Spin-Canting Transition in the Corrugated Square Net Compound Cu3(TeO4)(SO4)·H2O

“…The trigonal bipyramid coordination for Te is rarely observed in copper tellurium sulfates and, to the best of our knowledge, was reported only as a tetragonal pyramid in Cu 7 TeO 4 (SO 4 ) 5 • KCl 18. The average Te−O bond lengths of the title compound range from 1.9087(14) to 2.1285(18) Å, comparable to those of several other copper tellurium oxides such as Cu 7 TeO 4 (SO 4 ) 5 •KCl, Ba 2 Cu 2 Te 2 P 2 O 13 ,22 Cu 2 Te 3 O 8 ,20 Nb 2 Te 4 O 13 ,23 and BaCuTeO 3 TeO 4 24. The O ax −Te−O eq (axial and equatorial oxygens) bond angles in Cu 3 (TeO 4 )-…”

Syntheses and Structural Characterization of New Mixed-Valent Tellurium Oxides, A4[Te56+Te34+]O23 (A = Rb and K)

“…Had the Te(6), in compounds 1 and 2 , also been hexavalent and octahedrally coordinated with an additional oxygen atom, then the resulting A 4 Te 8 O 24 phases, with corrugated [Te 6 O 24 ] layers, would have constituted a new structural modification of the A 2 Te 4 O 12 compounds. There are a few structurally characterized, mixed-valent tellurium oxides known − in other ternary and quaternary systems, and they contain different proportions of Te 6+ with octahedral coordination and Te 4+ with trigonal-pyramidal or disphenoidal coordination. BaCuTe 2 O 7 and α and β modifications of Hg 2 Te 2 O 7 are two-dimensional compounds, , in which TeO 6 octahedra and TeO 4 disphenoids constitute [Te 6+ Te 4+ O 7 ] 4- layers that are interleaved with divalent cations.…”

Planare CuO4-Polygone und eine einseitig offene Te4+O3-Koordination in SrCuTe2O6 / Planar CuO4 Polygons and a One-Sided Open Te4+O3 Coordination in SrCuTe2O6

“…Beispiele hierfür sind die tetragonal pyramidale Koordination von 0 2~ um Te4+ in BaTe20 6 [4] und um Te(l) in CuTe0O5 [10]. Eine trigonal pyramidale Koordination des Tellurs liegt in B aC u(Te03)(T e04) [8 ] vor und wur de auch in CuTe20 5 um Te(2) beobachtet. Einseitig dreifach koordiniertes Tellur tritt im monoklinen SrTe03 auf (z.…”

“…An Bariumtelluriten sind bekannt: BaTe20 6 [4], eine orthorhombische Form von B aT e03 [5] und eine monokline [5,6], sowie Ba3Te40 n [7] mit parti ell sechswertigem Tellur. B aC u(Te03)(T e04) [8] ist bisher das einzige Erdalkalimetall-Kupfertellurit/-tellurat mit Te4+ in einseitig offener Koordina tion in Form einer trigonalen Bipyramide mit dem freien Elektronenpaar an einer der Pyramidenspit zen. Erwähnt sei, daß auch ein Tellurit des M agne siums, MgTe20 5 [9], bekannt ist.…”