Matrix isolation infrared and Raman spectra of binary and mixed zinc dihalides, isotopic effects, force constants, and thermodynamic properties

Raman and infrared matrix solution spectra for all ZnX2 and ZnXY (X,Y=Cl,Br,I) molecules are reported. These spectra complete the vibrational information on the binary dihalides and provide the first experimental evidence for the existence of the mixed zinc dihalides. All three fundamentals are assigned for all molecules. Isotopic effects due to the halogen atoms, the zinc atoms, or both were resolved in the stretching mode bands. From these, stretching, bending, and interaction force constants were evaluated, the criterion for their calculation being the reproduction of band frequencies within experimental error and the best fit of the frequency differences in the resolved isotopic fine structures. The possibility that not all molecules are linear is indicated. The effect of temperature and deviations from linearity on calculated entropies is shown.