Fluoride crystal structures. Part IV. Tellurium tetrafluoride

Abstract

Crystals of tellurium tetrafluoride are orthorhombic, space group P2₁2₁2₁, a= 5·36, b= 6·22, c= 9·64 Å. The structure was refined by three-dimensional least-squares methods, the final R being 0·084 for 376 reflections. Each tellurium atom in the structure is surrounded by three terminal and two bridging fluorine atoms arranged at the apices of a distorted square pyramid. The square-pyramidal units are linked by cis bridging atoms into endless chains with a bridge angle of 159°. The geometry of the [TeF₅] group is consistent with steric activity of the non-bonding electron pair and the arrangement can be described as a distorted octahedral co-ordination of the tellurium atom by five fluorine ligands and the electron pair.