Mössbauer spectra of some tellurium complexes

Abstract

Tellurium-125 Mössbauer spectra are reported for various tellurates and tellurites, and for a series of compounds of TeCl₆^2–, TeBr₆^2–, Tel₆^2–, and TeF₅^– with various cations. The chemical isomer shift is found to be characteristic of the onion and is rather insensitive to the nature of the cation. By use of compounds enriched in ¹²⁵Te, differences in chemical isomer shift as small as 3% of the Heisenberg width of the resonance can be detected with confidence. Trends deduced from previous data on the halogen complexes are shown to be in error. The spectrum of a frozen solution of CsTeF₅ in hydrofluoric acid is compatible with the presence of the TeF₅^– anion rather than TeF₆^2–. The significance of the results is discussed in terms of the sign of δR/R for ¹²⁵Te and the details of bonding in the complexes.