An unusual conformation of gabapentin (Gpn) in Pyr-Gpn-NH-NH-Pyr stabilized by weak interactions

Abstract

The crystal structure ofN-[(1-{2-oxo-2-[2-(pyrazin-2-ylcarbonyl)hydrazin-1-yl]ethyl}cyclohexyl)methyl]pyrazine-2-carboxamide monohydrate (Pyr-Gpn-NN-NH-Pyr·H2O), C19H23N7O3·H2O, reveals an unusualtrans–gauche(tg−) conformation for the gabapentin (Gpn) residue around the Cγ—Cβ(θ1) and Cβ—Cα(θ2) bonds. The molecular conformation is stabilized by intramolecular N—H...N hydrogen bonds and weak C—H...O interactions. The packing of the molecules in the crystal lattice shows a network of strong N—H...O and O—H...O hydrogen bonds together with weak C—H...O and π–π inteactions.