Characteristic Vibrations of CCl3F

(C3v or Cs symmetry)

CCl3F (trichlorofluoromethane, also known as CFC-11 or Freon-11) is a approximately tetrahedral. There do not appear to be significant natural sources of this molecule, and the current atmospheric abundance of ~0.268 ppb is the result of human activity. Like other chlorofluorocarbon molecules, CCl3F was synthesized as a refrigerant, in part because of its chemical inertness. Unfortunately, this chemical inertness allowed the CFC's to accumulate in the atmosphere (mean lifetime of  CCl3F ≈ 50 years). In the stratosphere CCl3F is fragmented by ultraviolet light, generating chlorine radicals (Cl•) that promote the decomposition of ozone. CFC production was phased out starting in the late 1980's. Human-induced emissions of CCl3F are a minor contributor to the Earth's enhanced greenhouse effect, adding a radiative forcing ≈ 0.07 Watts/m2 (IPCC).
Chlorine has two common stable isotopes (35Cl - 75.77%, 37Cl - 24.23%) that are mixed more or less randomly in CCl3F molecules, yielding both asymmetric (12C37Cl35Cl219F, ~41%; 12C37Cl235Cl19F, ~13% -- both with Cs symmetry) and symmetric (12C35Cl319F, ~43%; 12C37Cl319F, ~1% -- both with C3v symmetry) species. Both symmetric and asymmetric molecules have six distinct vibrational modes that all interact with infrared light, absorbing or scattering infrared heat radiation from the Earth before it can escape to space. The normal modes depicted below were modeled using hybrid density functional theory (B3LYP) and the cc-pVTZ basis set. Vibrational frequencies tabulated by Snels et al. (2001, J. Mol. Spectrosc. 205:102-109) are also shown -- values for the 12C35Cl319F, isotopologue are listed first, with values for 12C37Cl35Cl219F underneath. Symmetry species are shown for 12C35Cl319F. Listed frequencies have not been corrected for anharmonicity.

ν1 = 1081.3 cm-1 (sym.)
1080.7 (asym.)
A1 Symmetry

ν2 = 538.2 cm-1 (sym.)
535.6 cm-1 (asym.)
A1 Symmetry

ν3 = 351.4 cm-1 (sym.)
349.2 cm-1 (asym.)
A1 Symmetr

ν4 = 849.5 cm-1 (sym.)
848.7 cm-1 (asym.)
E Symmetry

ν5 = 399.2 cm-1 (sym.)
395.9 cm-1 (asym.)
E Symmetry

ν6 = 244.1 cm-1 (sym.)
242.2 cm-1 (asym.)
E Symmetry

  Go to Molecular Vibrations