(–)-(S)-N,N′-Bis[1-(1-naphthyl)ethyl]oxalamide

Abstract

The title molecule, C26H24N2O2, displays C2 symmetry, with the molecule located on a twofold axis perpendicular to the plane of the oxalamide unit –NH—CO—CO—NH–. The oxalamide core deviates from planarity, as reflected by the O=C—C=O and N—C—C—N torsion angles of 164.3 (5) and 163.2 (5)°, respectively. The naphthyl groups are oriented toward the same face of the oxalamide mean plane and make a dihedral angle of 43.76 (8)°. This conformation is suitable for the formation of intermolecular N—H...O hydrogen bonds, giving noncentrosymmetric dimers incorporating R22(10) ring motifs. These nonbonding interactions propagate along the 61 screw axis normal to the molecular twofold axis, resulting in a single-stranded right-handed helix parallel to [001]. In the crystal, Δ helices are arranged side-by-side and interact through π–π contacts between naphthyl groups. The shortest centroid–centroid separation between interacting benzene rings is 3.623 (4) Å.