Abstract
The infrared spectra of complexes of 1-methyl-2-pyridone and 1-methyl-2-quinolone with Lewis acids are consistent with interaction at the carbonyl group. The stretching frequency of this group, vco, is lowered on complex formation, the change being proportional to the Lewis acidity. Two other bands, at 1 670 and 1 380 cm−1 move to lower frequency in much smaller steps and are associated with ring modes.