Syntheses, structures, and characterization of new lead(II)-tellurium(IV)-oxide halides:: Pb3Te2O6X2 and Pb3TeO4X2 (X = Cl or Br)

The syntheses, structures, and characterization of four new lead(II)-tellurium(IV)-oxide halides, Pb3Te2O6X2 and Pb3TeO4X2 (X = Cl or Br) are reported. The materials are synthesized by solid-state techniques, using Pb3O2Cl2 or Pb3O2Br2 and TeO2 as reagents. The compounds have three-dimensional structural topologies consisting of lead-oxide halide polyhedra connected to tellurium oxide groups. In addition, the Pb2+ and Te4+ cations are in asymmetric coordination environments attributable to their stereoactive lone pair. We also demonstrate that Pb-3-Te2O6X2 and Pb2TeO4X2 can be interconverted reversibly through the loss or addition of TeO2. X-ray data: Pb-3-TeAC12, monoclinic, space group C2/m (No. 12), a = 16.4417(11) Angstrom, b = 5.6295(4) Angstrom, c = 10.8894(7) Angstrom, beta = 103.0130(10)degrees, Z = 4; Pb3Te2O6Br2, monoclinic, space group C2/m (No. 12), a = 16-8911(8) Angstrom, b = 5.6804(2) Angstrom, c = 11.0418(5) Angstrom, beta = 104.253(2)degrees, Z = 4; Pb3TeO4Cl2, orthorhombic, space group Bmmb (No. 63), a = 5.576(1) Angstrom, b = 5.559(1) Angstrom, c = 12.4929(6) Angstrom, Z = 4; Pb3TeO4Br2, orthorhombic, space group Bmmb (No. 63), a 5.6434(4) Angstrom, b = 5.6434(5) Angstrom, c = 12.9172(6) Angstrom, Z = 4.