title: Polytelluride
text: # Polytelluride
  
  In chemistry, a polytelluride usually refers to anions of the formula $(Te_n)^{2-}.$ Many main group and transition metals form complexes with polytelluride anions.
  
  ## Preparation
  
  Conceptually, polytellurides are derived from polytelluranes $H_2Te_n,$ but such neutral species are not known (even $H_2Te$ is labile). Instead, analogous to the preparation of many Zintl ions, polytellurides are produced by reduction of elemental Te with alkali metals. Such reactions can be conducted by heating a mixture of the solids or by dissolving Te metal in amine solvents of alkali metals. Once generated, these alkali metal polytellurides can be converted to lipophilic salts by treatment cryptand ligands or by ion exchange with quat salts.
  
  ## Structures
  
  Salts of polytellurides have often been characterized by X-ray crystallography. Polytelluride salts generally feature open chains, which adopt a zig-zag conformation. In some cases, cyclic structures are observed as in $Li_2Te_7,$ which features a square-planar Te center bound to two Te-Te-Te chains.
  
  As ligands in coordination complexs, polytellurides are generally bidentate. Complexes of penta-, tetra-, and tritelluride ligands are known. One example is the spirocyclic $[Zn(Te_4)_2]^{2-}.$
  
  