Crystal structures and Hirshfeld surface analyses of 2-amino-4-(4-bromophenyl)-6-oxo-1-phenyl-1,4,5,6-tetrahydropyridine-3-carbonitrile hemihydrate and 1,6-diamino-2-oxo-4-phenyl-1,2-dihydropyridine-3,5-dicarbonitrile

Abstract

In 2-amino-4-(4-bromophenyl)-6-oxo-1-phenyl-1,4,5,6-tetrahydropyridine-3-carbonitrile hemihydrate, C18H14BrN3O·0.5H2O, (I), pairs of molecules are linked by pairs of N—H...N hydrogen bonds, forming dimers with an R22(12) ring motif. The dimers are connected by N—H...Br and O—H...O hydrogen bonds, and C—Br...π interactions, forming layers parallel to the (010) plane. 1,6-Diamino-2-oxo-4-phenyl-1,2-dihydropyridine-3,5-dicarbonitrile, C13H9N5O, (II), crystallizes in the triclinic space group P\overline{1} with two independent molecules (IIA and IIB) in the asymmetric unit. In the crystal of (II), molecules IIA and IIB are linked by intermolecular N—H...N and N—H...O hydrogen bonds into layers parallel to (001). These layers are connected along the c-axis direction by weak C—H...N contacts. C—H...π and C—N...π interactions connect adjacent molecules, forming chains along the a-axis direction. In (I) and (II), the stability of the packing is ensured by van der Waals interactions between the layers. In (I), Hirshfeld surface analysis showed that the most important contributions to the crystal packing are from H...H (37.9%), C...H/H...C (18.4%), Br...H/H...Br (13.3%), N...H/H...N (11.5%) and O...H/H...O (10.0%) interactions, while in (II), H...H interactions are the most significant contributors to the crystal packing (27.6% for molecule IIA and 23.1% for molecule IIB).

Keywords

• crystal structure
• disorder
• hydrogen bonds
• dimers
• van der waals interactions
• hirshfeld surface analysis