Proton magnetic non-equivalence in the 1,3,5-trinitropentadienide system of certain Meisenheimer complexes
Abstract
N.m.r. spectra have been recorded for a series of asymmetrical Meisenheimer complexes of 1,3,5-trinitrobenzene. In certain of the complexes the protons of the 1,3,5-trinitropentadienide system show a chemical shift difference of about 0·1 p.p.m. It is argued that such a chemical shift difference reflects the existence of hindered rotations.