Time-resolved resonance Raman and density functional study of the radical cations of chlorobiphenyls

We have obtained time-resolved resonance Raman spectra of the radical cations of 4-chlorobiphenyl, 3-chlorobiphenyl, and 2-chlorobiphenyl. We have performed density functional theory B3LYP/6-31G∗∗ calculations to find the optimized structures and predicted vibrational spectra for the ground states of the chlorobiphenyl radical cations. The computational and experimental results suggest that all of these chlorobiphenyl radical cations are nonplanar. The 2-chlorobiphenyl radical cation is noticeably more nonplanar than the other two radical cations and this appears to be due mainly to steric interactions. The radical cations are more noticeably nonplanar than the corresponding T1 states of the neutral molecules.