Structure of the molecules of alkali metal tetrachloroaluminates

metal atom in the function of the molecular component of the intensity of scattering sM(s), because of the large charge of the nucleus of the chlorine atom, is smaller for tetrachloroaluminates than for tetrafluoroaluminates, so that the position of the metal atom is determined less reliably. There is no published information on the vibrational spectra of tetrachloroaluminates, and no quantum-mechanical calculations have been carried out, so that the results and conclusions of the present work are based only on the data obtained in the hightemperature electron diffraction study, carried out to investigate the structure in the series KAICI4, RbAICI4, and CsAICI~. The study of the KAICIa molecule was described in detail earlier [5]. It may be noted that the work carried out could not give an unambiguous answer concerning the structure of the KAICIa molecule [5]. It is only after comparison with the results of the present study of the structure of the RbAICIa and CsAICI~ molecules that it is possible to reach a definite conclusion about the structure of the equilibrium configuration of the KAICI~ molecule. The apparatus and procedure used to obtain and process the electron diffraction patterns were the same as in the study of the KAICI, molecule [5]. The specimens taken for the volatilization were equimolar melts of AICI3 and MCI (where M = Rb, Cs). The temperature close to the jet of the molybdenum ampul was 580-660~ for RbAICIa, and 560-580~ for CsAICI4. Tensimetric studies have shown that under the conditions of the experiment, the vapor contains TABLE i. Values of the Internuclear Distances r a and the Mean Amplitudes of the Vibrations I m for the RbAICI4 and CsA!CIa Molecules