The vibrational spectra of some penta- and hexa-halogeno-complexes of tin, titanium, and tellurium

Abstract

The preparation of the salts (Et₄N)SnCl₅, (Bu₄N)SnCl₅, (Et₄N)SnBr₅, (Et₄N)TiCl₅, (Et₄N)Ti₂Cl₉, (Et₄N)TeCl₅, and (Et₄N)Te₃Cl₁₃ is described; the infrared spectra (400–90 cm.^–1) of all the compounds and the Raman spectra of the tin compounds are reported. The spectra indicate that the tin and titanium compounds are salts of the trigonal bipyramidal ions SnCl₅^–, SnBr₅^–, and TiCl₅^– while for the TeCl₅^– ion the symmetry is probably lower than that of a square pyramidal structure. For (Et₄N)Te₃Cl₁₃ the probable structure is (Et₄N⁺)(TeCl₃⁺)₃(Cl^–)₄, and (Et₄N)Ti₂Cl₉ appears to contain the chlorine-bridged Ti₂Cl₉^– ion. The assignment of the vibrational spectra of solid tellurium tetrachloride is discussed.

The infrared spectra of some salts of the hexahalogeno-ions SnCl₆^–, SnBr₆^–, TiCl₆^2–, TeCl₆^2–, TeBr₆^2–, and the Raman spectra of the TeCl₆^2– and TeBr₆^2– ions are also reported, and evidence is presented for interaction between the anion bending fundamental ν₄ with lattice modes for the tin and tellurium compounds.