The vibrational spectra of the halides, complex halides and mixed halides of thallium(III). Part I. The vibrational spectra of TlBr3, TlBr4, TlCl63– and TlCl4–

Abstract

The Raman spectrum of a solution of thallic bromide in ethanol to which lithium bromide has been added is compatible with the existence of the TlBr₄ anion (symmetry T_d). A number of other solutions containing this anion were also investigated. The i.r. and Raman spectra of solutions of thallic bromide in ethanol and in tri-n-butyl phosphate (TBP) indicate that these solutions consist of a mixture of TlBr₃ and TlBr₄^–, and not the TlBr₄^– anion alone as reported previously. The Raman spectrum of a solution of thallic chloride in 1 OM-aqueous lithium chloride shows that this solution contains the TlCl₆^3– anion, of point group O_h. The tri-n-butyl phosphate extract of this solution gives the Raman spectrum of the TlCl₄^– anion. A number of other solutions containing this anion are also investigated. The far-i.r. spectrum (20–400 cm.^–1) of NEt₄TlCl₄ is also reported. Solutions of NEt₄TlCl₃Br and NEt₄TlBr₃Cl in acetonitrile are shown to consist of mixtures of the TlBr₄^– and TlCl₄^– anions.