Intermolecular Interactions of Trichloromethyl Group in the CrystalState, the Case of 2‑Trichloromethyl‑3H‑4-quinazoline Polymorphsand 1‑Methyl-2-trichloroacetylpyrrole−Hirshfeld Surface Analysis ofChlorine Halogen Bonding

Intermolecular interactions in the crystal state, apossible source of the observed polymorphism, are investigatedwith the use of the combined crystallographic methods, theoreticalcomputations, and a modern approach of Hirshfeld surface analysis.Special attention is paid to a trichloromethyl group, a potentialdonor of halogen bonding. It is demonstrated that due to packingeffects and stacking interactions, its conformation does not have tocorrespond to the lowest energy structure of an isolated molecule,leading to formation of different polymorphs. The analysis ofHirshfeld surfaces, in contrast to standard geometrical criterion ofsum of van der Waals radii, indicates the dominant role of variouschlorine intermolecular contacts into the overall molecular packing and reveals the characteristic features of the obtainedfingerprint plots. These interactions, a subject of our special interest, are discussed in details in order to provide theircomprehensive description by means of Hirshfeld surface analysis tools