Halogen bonds versus hydrogen bonds in the crystal packing formation of halogen substituted anilines

The regularities of crystal structure organization were studied in a series of para- and ortho-halogenanilines using an approach based on comparison of interaction energies between molecules calculated by an ab initio method. The halogen substituent position in anilines significantly affects intermolecular interactions, differing between para- and ortho-halogen anilines. In para-halogen anilines, the amino group mainly acts as a hydrogen-bond donor, with no significant halogen bonds and weak stacking interactions. In ortho-halogen anilines, the amino group functions as both donor and acceptor, with stronger hydrogen and halogen bonding. Crystal packing analysis shows columnar organization across samples, with zig-zag columns in para-substituted anilines and triple columns in ortho-substituted ones. Overall, halogen bonds play a minor role, mainly connecting neighboring columns.