Probing the Electronic Properties and Interaction Landscapes in a Series of -(Chlorophenyl)pyridinecarboxamides.

A 3 × 3 isomer grid of nine -(chlorophenyl)pyridinecarboxamides () is reported with physicochemical studies and single crystal structures ( = pyridinoyl moiety; = aminochlorobenzene ring; = -/-/-), as synthesized by the reaction of the substituted -/-/-pyridinecarbonyl chlorides () with -/-/-aminochlorobenzenes (). Several of the nine crystal structures display structural similarities with their halogenated and methylated relatives ( = -//-substitutions; = F, Br; = methyl). Indeed, five of the nine crystal structures are isomorphous with their analogues as the /, /, /, /, and / pairs. In the series, the favored hydrogen bonding mode is aggregation by N-H···N interactions, though amide···amide intermolecular interactions are noted in and . For the triad, intramolecular N-H···N interactions influence molecular planarity, whereas (as a monohydrate) exhibits O-H···O, N-H···O1W, and O1W-H···N interactions as the primary hydrogen bonding. Analysis of chlorine-containing compounds on the CSD is noted for comparisons. The interaction environments are probed using Hirshfeld surface analysis and contact enrichment studies. The melting temperatures ( ) depend on both the lattice energy and molecular symmetry (Carnelley's rule), and the melting points can be well predicted from a linear regression of the two variables. The relationships of the values with the total energy, the electrostatic component, and the strongest hydrogen bond components have been analyzed.