Molecular and electronic structures as well as vibrational spectra assignment of biphenyl, 2,2′- and 4,4′-dichlorobiphenyl from density functional calculations

Density functional calculations of biphenyl, 2,2′-dichlorobiphenyl and 4,4′-dichlorobiphenyl are performed. The geometries and electronic structures of these compounds are reported and the substituent effects of the chlorine atoms and the reactivity of the compounds are discussed. The IR frequency/intensity are calculated for these compounds and compared with corresponding experimental results. The vibrations are assigned assisted with animated pictures. The wrong report of the B1 vibration modes for biphenyl in a previous research work is pointed out.