Hydrogen bonding in nitroanilines: Neutron diffraction study of m-nitroaniline at 100 K

An appreciable degree of pyramidalization of the amine nitrogen atom is obs erved 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 confirme d. 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 struc ture can be described as polar layers on the be plane, embodying chains int erlinked by N-H . . .N interactions and connected by weak C(aryl)-H . . .O interactions.