(Contribution from the laboratory for prop. inorganic chemistry and from the laboratory for general and inorganic chemistry of the University of Amsterdam).Raman spectra of the addition compounds TeCl, . AlCl, and S e a , . MCl, 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 TeCl,.AlCI, 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 AIC1,-ion.The findings point to an ionic structure for both compounds (TeCI,+ . AlC1,-and SeCl,+ . ma,-). The assigned frequency values for TeU,+ and Sea,+ in these compounds are somewhat higher than the corresponding lines in TeU, and SeCl,. This makes it probable that the interaction between TeU,+ (and SeCI,+) and its surrounding anions (Cland A Q -respectively) is stronger in the compound T e a , (and SeCI,) than in the corresponding addition compound. Force constants have been calculated for T e a , + in the compound TeCI, . AICl,.