Hydrogen Bonding in Nitroanilines:  Neutron Diffraction Study of m-Nitroaniline at 100 K

An appreciable degree of pyramidalization of the amine nitrogen atom is observed in the title compound. The existence of polar chains, induced by N−H···O synthons and stabilized by a C(ar)−H···O interaction, is confirmed. An N−H···N interaction, disregarded in molecular orbital calculations, was found to stabilize even further the known head-to-head assembling of the chains and to be responsible for the polar layer's formation. The structure can be described as polar layers on the bc plane, embodying chains interlinked by N−H···N interactions and connected by weak C(aryl)−H···O interactions.