The infrared intensities and polar tensors of the fluorochloromethanes

The polar tensors of CF3Cl, CF2Cl2 and CFCl3 have been calculated using rec ent measurements of their gas phase infrared fundamental intensities. The p olar tensors obtained for CF2Cl2 and CFCl3 are in very good agreement with those obtained previously since the more recent experimental intensity resu lts are in good agreement with those reported earlier. For CF2Cl2 <(<rho>)o ver bar>(C) = + 1.626, <(<rho>)over bar>(F) = - 0.577 and <(<rho>)over bar> (Cl) = - 0.26e whereas <(<rho>)over bar>(C) = + 1.369, (P) over bar (F) = - 0.478 and <(<rho>)over bar>(Cl) = - 0.297e for CFCl3. However, two sets of significantly different mean dipole moment derivatives are obtained from t he experimentally measured intensities of CF3Cl reported by two different l aboratories. 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 ar e sufficient to indicate which set is the correct one. As such average valu es of <(<rho>)over bar>(C) + 1.907 +/- 0.178e, <(<rho>)over bar>(F) - 0.590 +/- 0.056e and <(<rho>)over bar> = - 0.139 +/- 0.013e obtained from both s ets of polar tensor elements are recommended for the CF3Cl mean dipole mome nt derivatives. (C) 2001 Elsevier Science B.V. All rights reserved.