A rare multi-coordinate tellurite, NH4ATe4O9·2H2O (ARb or Cs): The occurrence of TeO3, TeO4, and TeO5 Polyhedra in the same material

Two new tellurites, NH4RbTe4O9·2H2O and NH4CsTe4O9·2H2O have been synthesized and characterized. The compounds were synthesized hydrothermally, in near quantitative yields, using the alkali metal halide, TeO2, and NH4OH as reagents. The iso-structural materials exhibit layered, two-dimensional structural topologies consisting of TeOx (x=3, 4, or 5) polyhedra separated by NH4+, H2O, Rb+ or Cs+ cations. Unique to these materials is the presence of TeO3, TeO4, and TeO5 polyhedra. Thermogravimetric and infrared spectroscopic data are also presented. Crystal data: NH4RbTe4O9·2H2O: Monoclinic I2/a (no. 15), a=18.917(3) Å, b=6.7002(11) Å, c=21.106(5) Å, β=101.813(2)°, V=2618.5(9) Å3, Z=8; NH4CsTe4O9·2H2O: Monoclinic I2/a (no. 15), a=18.9880(12) Å, b=6.7633(4) Å, c=21.476(2) Å, β=102.3460(10)°, V=2694.2(3) Å3, Z=8.

Two unprecedented tellurites, NH4ATe4O9·2H2O (A=Rb or Cs) have been synthesized and characterized. The materials represent rare examples of tellurites that contain TeO3, TeO4, and TeO5 polyhedra in the same compound. All of the polyhedra are in asymmetric polar coordination environments attributable to their stereo-active lone-pair.Figure optionsDownload as PowerPoint slide