Crystallographic studies of intra- and inter-molecular interactions. Crystal and molecular structure of N,N-dimethyl-4-nitro-3,5-xylidine. Structural evidence against the classical through-resonance concept in p-nitroaniline and derivatives

Abstract

An analysis of the geometry of N,N-dimethyl-4-nitroaniline and its 3,5- and 2,6-dimethyl derivatives presents structural evidence against the classical concept of through-resonance(throughconjugation), according to which the most important contribution is the quinoid structure with full charge transfer from the amine to the nitro group. Application of the HOSE model gives results which are in line with calculations performed by Hiberty and Ohanessian on p-nitroaniline.