화학공학소재연구정보센터
Journal of Physical Chemistry A, Vol.112, No.14, 3127-3132, 2008
Ab initio study of the interaction of CHX3 (X = H, F, Cl, or Br) with benzene and hexafluorobenzene
In this paper, the results of a study of the interaction of methane, fluoroform, chloroform, and bromoform with benzene and hexafluorobenzene are presented. The benzene complexes were studied at the MP2/6-31G(d) and MP2/6-311++G(2d,p) levels, and the hexafluorobenzene complexes were only studied at the MP2/6-31G(d) level. The optimized geometries, stabilization energies, potential energy surfaces, harmonic frequencies, and vibrational intensities are reported. A net attraction is predicted for all four benzene complexes, whereas for the CHX3 center dot C6F6 complexes, it was found that MP2/6-31G(d) predicts a net attraction for the CH4, CHCl3, and CHBr3 complexes and does not predict a stable complex for CHF3 center dot C6F6. The three complexes with net attractions all have blue-shifts of the CHX3 CH stretching wavenumber and a slight contraction (0.001-0.003 angstrom) of the CH bond in CHX3. The MP2/6-31G(d) level predicts that the intensity of the CHX3 CH stretch will vary widely. For CH4 center dot C6H6 and CHF3 center dot C6H6, it is predicted that the intensity will be smaller for the complexes than the free molecules, whereas for the other complexes, anywhere from a 30% increase to an increase of 87 times is predicted. The atoms in molecules analysis showed that only three of the eight criteria for normal hydrogen bonding are satisfied for all eight complexes studied. Criterion 3 (value of the Laplacian at the bond critical point) is not satisfied for any of the eight complexes.