Ab initio calculations of vibrational frequencies, potential functions of internal rotations and vibrational infrared and Raman spectra for 3,3,3-trifluoropropanal

The conformational behavior and structure of 3,3,3,-trifluoropropal have been investigated by utilizing ab initio calculations with the 6-31G** basis set (valence double zeta basis with polarization functions on all atoms) at the restricted Hartree Fock (RHF), second-order Moller-Plesset perturbation (MP2), and Density Functional (B3LYP) levels. The molecule is predicted to have a cis double left right arrow gauche conformational equilibrium. Full optimization of the transition states was performed and the rotational barriers of both the CHO and CF3 rotors were calculated. Vibrational frequencies were computed at the three levels and the zero-point corrections were included into the calculated asymmetric CHO rotational barrier. Complete vibrational assignments were made on the basis of normal coordinate calculations for both stable conformers of the molecule.