Two polymorphs of N,N′-diphenyl-2-[1-(propylamino)ethylidene]propanediamide

Abstract

Two polymorphs of the title compound, C20H23N3O2, have been isolated. Polymorph (I) crystallizes in the monoclinic space group P2 1/n and polymorph (II) in the tetragonal space group I4 1/a. The main difference between the two polymorphs on the molecular level is the orientation of the n-propyl group. This group is antiperiplanar in (I) and synclinal in (II). The core of the molecule consists of two carbamoyl units bound to an enamine unit. The most prominent features are intramolecular N—H...O hydrogen bonds in both polymorphs. Both polymorphs form dimers with graph set R 2 2(12) via intermolecular N—H...O hydrogen bonds. Adjacent dimers of (I) are connected via a weak C—H...O interaction, resulting in a chain parallel to the crystallographic a-axis. The dimers of (II) are connected by weak C—H...π interactions, forming intermolecular chains along the c-axis direction.