The structure of selenium tetrachloride in the solid and of tellurium tetrachloride in the liquid and the solid state

Raman spectra were obtained for SeCl4 in the solid and for TeCl4 in the solid and the liquid state. Polarization measurements were performed for the stronger Raman lines of liquid TeCl4. The four stronger Raman lines of SeCl4 are very close in frequency to those of pyramidal AsCl3; there is also a close analogy between the frequencies of the stronger Raman lines of TeCl4 (both in the solid and in the liquid state) and those of antimony trichloride. These findings favour the assumption that solid SeCl4 and TeCl4 have to be written as SeCl3+Cl− and TeCl2+Cl− respectively, SeCl3+ being isosteric with AsCl3 and TeCl2+ with SbCl3. Force constant and frequency calculations have been effected for the hypothetical SeCl3+ and TeCl3+ ions. The results support the above assumption.