Tellurium Polycations Stabilized by Halogenobismutates – Syntheses and Crystal Structure of te4[bi6Cl20] and te4[bi2br8]

The reaction of Te, TeX4 and BiX3 [X = Cl, Br] in sealed, evacuated glass ampoules in the temperature range 170° 100°C yields a variety of compounds composed of tellurium polycations and halobismutate anions. Two of these have been identified by crystal structure analyses as Te4[Bi6Cl20] (triclinic, P., a = 738.8(2), b = 875.1(2), c = 1389.1(6) pm, α = 87.89(2), β = 82.87(4), γ = 87.89(2) ·, Z = 1) and Te4[Bi2Nr8 (triclinic, P., a = 726.0(4), b = 773.7(4), c = 901.8(5) pm, α = 92.95(2), β = 102.23(2), γ = 92.87(2)., Z = 1). Both compounds were obtained as black crystals with a violet lustre and contain square-planar Te42+ cations. Te4[Bi6Cl20] contains a two-dimensional polymeric anion [Bi6Cl20]2− made up of corner- and edge-sharing BiCl6 octahedra with attached BiCl3 groups. The Bi–Cl distances vary over a very wide range from 245 to 334 pm. Te4[Bi2Br8] consists of a onedimensional chain [BiBr2Br4/2−[n of cis-edge-connected BiBr6 octahedra with Bi–Br distances ranging from 264 to 318 pm.