Vibrational Spectra, Potential Constants, and Calculated Thermodynamic Properties of cis- and trans-BrHC=CHBr, and cis- and trans-BrDC=CDBr

Abstract

Raman displacements for the liquid and infrared absorption wave numbers for both liquid and gas, together with quantitative depolarization factors for the Raman lines and semiquantitative relative intensities for both Raman and infrared bands, have been obtained for cis‐ and trans‐BrHC=CHBr and cis‐ and trans‐BrDC=CDBr. Assignments, consistent with the selection rules, were made for the 4 molecules. As a further check on the assignments a normal coordinate treatment (Wilson FG matrix method) was carried out. The heat content, free energy, entropy, and heat capacity for each of the molecules were calculated for 12 temperatures from 100 to 1000°K for the ideal gaseous state at 1 atmos pressure. Finally the energy difference between the cis‐ and trans‐isomers of C₂H₂Br₂ has been calculated.