The electronic absorption and vibrational spectra of 2,6-and 3,5-dichlorobenzonitriles

The electronic absorption spectra of 2.6- and 3,5-dichlorobenzonitriles have been photographed in vapour phase on medium quartz spectrograph. The observed spectra correspond to A1g → B2u transition of benzene. The 0,0 band of the observed absorption systems for 2,6- and 3,5-dichlorobenzo- nitriles have been identified at 34 015 and 34 262 cm-1 respectively. Best of the bands were assigned as ground and excited state fundamentals, their combinations and overtones. In the case of 2,6-dichlorobenzonitrile the shorter wavelength band system corresponding to A1g → B1u transition of benzene has also appeared. The infrared absorption spectra of these mole- cules have also been studied in the region (200-4 000 cm-1). The assigned ground and excited state fundamentals from ultraviolet absorption spectra have been correlated with infrared data