Quantitative investigation of intermolecular interactions in dimorphs of 3-Chloro-N-(2-fluorophenyl)benzamide and 2-Iodo-N-(4- bromophenyl)benzamide

Abstract: In this study, we have analyzed the role of different intermolecular interactions in the polymorphic modifications of 3-chloro-N-(2-fluorophenyl)benzamide (I) and 2-iodo-N-(4- bromophenyl)benzamide (II). The crystals were obtained via slow evaporation method with the alteration of solvents for crystallization. The already reported form [Cryst. Growth Des. (2011) 11:1578] crystallizes in P2₁/c with Z^′=2 [Form IA], while the new form crystallizes in Pna2₁ with Z^′=1 [Form IB]. The latter compound crystallizes in P2₁/n with Z^′=1 [Form IIA] and in Pbca with Z^′=1 [Form IIB]. Weak Cl· · · Cl and C-H· · · F interactions in the former (IA, IB) and weak I· · · I and C-H· · · π interactions in the latter (IIA, IIB) play a vital role in the formation of different polymorphic modifications leading to the observation of conformational and packing polymorphs, respectively. PIXEL calculations show that most of the interactions present in the crystal structures are dispersive in nature. 2D Fingerprint plots revealed that the relative contribution of different intermolecular interactions in different polymorphic forms was different. Graphical abstract: SYNOPSIS We have analyzed the role of different intermolecular interactions and evaluated their contributions in the polymorphic modifications of 3-chloro-N-(2-fluorophenyl)benzamide (I) and 2-iodo-N-(4- bromophenyl)benzamide (II).