Solvatomorphism in (Z)-4-fluoro-N′-(3-fluorophenyl)benzimidamide: the role of intermolecular O–H⋯F interaction

Abstract

The synthesized compound (Z)-4-fluoro-N′-(3-fluorophenyl)benzimidamide exhibits solvatomorphism in the solid state. The anhydrous and the hydrate forms were obtained at room temperature from slow evaporation of cyclohexane and hexane solvents, respectively. Both forms crystallize in the triclinic P with two symmetry-independent molecules in the asymmetric unit. The crystal packing of the anhydrous form is stabilized via a strong N–H⋯N chain, whereas the hydrate form is stabilized via a strong (N–H⋯N)–(N–H⋯O)–(O–H⋯N) chain. The water molecule plays an important role in the crystal packing by the formation of “extremely short” N–H⋯O and O–H⋯N hydrogen bonds, which are further supported by weak O–H⋯F–C and C–H⋯O interactions. The basic structural building motifs were structurally and energetically equivalent in both forms. PIXEL and QTAIM approaches provide quantitative insights into the nature and energetics of strong as well as weak intermolecular interactions. The NCI descriptor shows the “attractive” nature of the rarely observed O–H⋯F interaction. The thermal stabilities of the solvatomorphs were characterized via differential scanning calorimetry, hot stage microscopy, and thermogravimetric analysis. Hirshfeld surface analysis and 2D fingerprint plots of the individual molecules present in both forms differentiate the trends in crystal packing as well as the contribution from the different intermolecular interactions.