Vibrational spectra of halides and complex halides. Part III. Hexahalogenotellurates

Abstract

Raman and far-infrared spectra of solid halogenotellurates, M₂^I[TeX₆], are reported and discussed. ν₃ Is unusually broad and sometimes split, but the splitting is not different in origin from those shown by other [MX₆]^2– ions. It is concluded that there is no static distortion due to the lone pair but that the breadth of ν₃ is associated with its presence in a symmetric orbital, as suggested by Urch. His description also accounts for the anomalous ratio of the bond-stretching force constants, K(Te–Br)/K(Te–Cl), which we find.