Multiplicity of Te–Te Bonds in Tellurium-Containing Lanthanide Compounds

The structures of 272 compounds containing 337 LnTe_n coordination polyhedra, where Ln is any lanthanide from La to Lu in the crystals, are analyzed using Voronoi–Dirichlet(VD) polyhedra. It is shown that the parameters of VD polyhedra allow determination of the valence state of Ln atoms. It is established that tellurides contain Ln(II) and Ln(III) atoms bonding from 4 to 9 tellurium atoms that exist as Te^2–or Tе⁻ ions. The VD polyhedra of Te atoms are determined and it is found that homoatomic Te–Te bonds appear only when there is a deficit of electron donor metal atoms in the composition of crystalline compounds. The dependence of the multiplicity of the Te–Te covalent bond on its length is revealed through the parameters of VD polyhedra. The reliability of this dependence is tested for some compounds, including polytellurides containing 4⁴ networks of tellurium atoms.