Influence of reactant 4-Aminobenzonitrile inclusion on the crystal structure of (Z)-4-(4-oxopent-2-en-2-ylamino)benzonitrile

The title compound (Z)-4-(4-oxopent-2-en-2-ylamino)benzonitrile, C ₁₂H₁₂N₂O, was synthesized by the condensation of acetylacetone and 4-aminobenzonitrile in methanol, with a few drops of formic acid as catalyst. Crystallization of the reaction product solution yielded both pure crystals of the title compound, as well as an inclusion product with a strict 1:1 stoichiometry with one of the reactants, 4-aminobenzonitrile. Crystals of the reactant-inclusion compound, C₁₂H₁₂N ₂O-C₇H₆N₂ (I), and pure C ₁₂H₁₂N₂O (II) have been determined at 143(2) and 88(2) K, respectively. The mixed-form crystals crystallized in the monoclinic system, whereas pure-form crystals crystallized in the triclinic system. Intramolecular hydrogen bonds of the type N-H···O were observed in both the mixed and pure-form crystals. However, in the mixed-form, the two components are connected by a N3- H3···N2 intermolecular hydrogen bond, which gives rise to a planar structure and parallel packing of adjacent molecules. In contrast, the structure of the pure compound without any reactant molecule interactions is not planar and exhibits a more complicated stacking array for adjacent molecules. Graphical Abstract: The title compound (Z)-4-(4-oxopent-2-en-2-ylamino) benzonitrile, C₁₂H₁₂N₂O, was synthesized by the condensation of acetylacetone and 4-aminobenzonitrile in methanol. Crystallization of the reaction product solution yielded both pure crystals of the title compound, as well as an inclusion product with a strict 1:1 stoichiometry with one of the reactants, 4-aminobenzonitrile. The mixed-form crystals crystallized in the monoclinic system, whereas pure-form crystals crystallized in the triclinic system. Intramolecular hydrogen bonds of the type N-H···O were observed in both the mixed and pure-form crystals. However, in the mixed-form, the two components are connected by a N3-H3···N2 intermolecular hydrogen bond, which gives rise to a planar structure and parallel packing of adjacent molecules. In contrast, the structure of the pure compound without any reactant molecule interactions is not planar and exhibits a more complicated stacking array for adjacent molecules.[Figure not available: see fulltext.]