Investigation of the structure of the compounds TeCl4 · AlCl3 and SeCl4 · AlCl3 by means of the Raman effect

Raman spectra of the addition compounds TeCl4 · AlCl3 and SeCl4 · AlCl3 in the liquid as well as in the solid state show, besides other lines, three more or less characteristic strong lines, for which in the case of liquid Tecl4. AlCl3 some information has been obtained with regard to their polarization state. The frequencies of these lines are compared with those of the component parts and of the AlCl4−; ion. The findings point to an ionic structure for both compounds (TeCl3+ · AlCl4− and SeCl3+ · AlCl4−). The assigned frequency values for TeCl3+ and SeCl3+ in these compounds are somewhat higher than the corresponding lines in TeCl4 and SeCl4. This makes it probable that the interaction between TeCl3+ (and SeCl3+) and its surrounding anions (Cl− and AlCl4− respectively) is stronger in the compound TeCl4 (and SeCl4) than in the corresponding addition compound. Force constants have been calculated for TeCl3+ in the compound TeCl4 · AlCl3.