The infrared intensities and polar tensors of the fluorochloromethanes

Abstract

The polar tensors of CF 3Cl, CF 2Cl 2 and CFCl 3 have been calculated using recent measurements of their gas phase infrared fundamental intensities. The polar tensors obtained for CF 2Cl 2 and CFCl 3 are in very good agreement with those obtained previously since the more recent experimental intensity results are in good agreement with those reported earlier. For CF 2Cl 2 ρ ̄ C =+1.626, ρ ̄ F =−0.577 and ρ ̄ Cl =−0.26e whereas ρ ̄ C =+1.369, P ̄ F =−0.478 and ρ ̄ Cl =−0.297 e for CFCl 3. However, two sets of significantly different mean dipole moment derivatives are obtained from the experimentally measured intensities of CF 3Cl reported by two different laboratories. On the other hand, the differences in the mean derivatives of these two sets are not large enough so that results from electronegativity models, potential models for core ionization energies and quantum chemical calculations at the Moller-Plesset 2 and B3LYP density functional levels are sufficient to indicate which set is the correct one. As such average values of ρ ̄ C =+1.907±0.178e, ρ ̄ F =−0.590±0.056e and ρ ̄ Cl =−0.139±0.013e obtained from both sets of polar tensor elements are recommended for the CF 3Cl mean dipole moment derivatives.