Substituent effects in infrared spectroscopy. Part 6. meta- and para-Substituted N-ammoniobenzamidates

Abstract

The i.r. spectra from 1 300 to 1 650 cm^–1 of a number of meta- and para-substituted N-ammoniobenzamidates have been studied. The strong bands near 1 560 and 1 355 cm^–1 in water are assigned to asymmetrical and symmetrical stretching vibrations of the CO group. The coupling of ν_a(CO) and ν₈ ring modes is shown up by the solvent variation method. It causes the failure of the Hammett equation for ν_a(CO). The similarity of the mechanics of vibration of the benzamidate and benzoate groups is emphasized.