A dynamic polarization model for vibrational optical activity and the infrared circular dichroism of a dihydro[5]helicene

The vibrational circular dichroism of (S)-(+)-9,10-dihydrodibenzo[c,g]-phenanthrene has been obtained over the frequency region of the C-H stretching mode fundamentals. A major contribution to the vibrational optical activity of the CH 2 groups is found to originate in the dynamic polarization of the naphthalene ring systems of the enantiomer by the transition dipole of the localized symmetric or antisymmetric C-H stretching mode of each group. An analogous mechanism accounts for the optical activity observed in the frequency region of the aromatic C-H stretching fundamentals.