Infrared Spectra Of CF2=CHD and CF2=CD2: Scaled Quantum-chemical Force Fields And An Equilibrium Structure For 1,1-difluoroethylene
Infrared (IR) spectra in the gas phase are reported for CF2=CHD and CF2=CD2 in the region 350-4000 cm(-1). Ab initio calculations of an harmonic force-field and anharmonicity constants have been made with an MP2/aug-cc-pVTZ model. These enable a number of Fermi resonances in each species to be analyzed and a complete set of "observed" harmonic frequencies to be derived. The latter are combined with similar data for CF2=CH2 in a scaling of the model harmonic force field to both anharmonic and harmonic frequencies. Inspection of the scale factors reveals minor defects of the model, evident in the out-of-plane wagging modes and in the CF stretch/CF stretch interaction force constant. Fermi resonance treatments involved in all isotopomers studied are compatible with the overall force-field refinement results. The treatment leaves a small anomaly in the C-13 shift on v(1). Improved microwave spectra are reported for five isotopic species, and a semiexperimental equilibrium structure for F2C=CH2 is determined and compared favorably with the structure obtained from new high-level ab initio calculations. Centrifugal distortion constants are predicted for the five isotopic species, and those for F2C=CH2 are compared with values fit to microwave spectra.
McKean, Donald C., Mark M. Law, Peter Groner, Andrew R. Conrad, et al. 2010. "Infrared Spectra Of CF2=CHD and CF2=CD2: Scaled Quantum-chemical Force Fields And An Equilibrium Structure For 1,1-difluoroethylene." Journal Of Physical Chemistry A 114(34): 9309-9318.
American Chemical Society
Journal of Physical Chemistry A
Chemistry and Biochemistry
Correlated molecular calculations, Phase electron-diffraction, Gaussian-basis sets, Vibrational anharmonicity, Microwave spectra, Ab initio calculations, Difluoroethylenes, Butadiene, Hydrogen, Ethylene, Chemistry, physical, Physics, atomic, molecular & chemical