Substituent effects in infrared spectroscopy-VII. Meta and para substituted methanesulphonanilides

Article abstract of DOI:10.1016/0584-8539(82)80069-X

Substituent effects on the NH frequencies of the conformers of methanesulphonanilides, their cyclic dimers and their hydrogen bonded complexes with acetonitrile have been analysed by means of the Hammet equation.An electron-withdrawing substituent may either increase or decrease ν(NH) in the XC6H4NHY series according to the electronic nature of the Y group.This can be explained by the non-monotonic dependence of the NH stretching frequency on the ionic character of the NH bond.