A study of conformation about the aryl C-N bonds in N-aryl imides by dynamic N.M.R. spectroscopy

Abstract

A series of α, β-(9,10-dihydroanthracene-9,10-diyl)-N-arylsuccinimide derivatives has been prepared and their N.M.R. spectral studies are reported. The effect of the substituents at the N-phenyl group on the conformational process about the aryl C-N bond has been investigated.The asymmetric cage moiety present in this system was employed for the conformational study.  The N.M.R. spectra provided evidence for the non-planar conformation and restricted rotation about the aryl C-N bond in the case of ortho-substituted derivatives. Electronegative substituents were found to have a preferred conformation (anti to the cage moiety). The energy barrier (ΔGt) of the order of 86 kJ/mol has been determined by their temperature-dependent spectra. Free rotation about the aryl C-N bond was observed for the meta- and para-substituted derivatives. No buttressing effect by meta substituents has been noticed.