Low Temperature X-Ray Crystallographic Structure of the Antiplasmodial Compound 5-N-Hydroxyethanequindoline Hydrochloride 0.5CH3OH.

Abstract

The structure of 5-N-hydroxyethanequindoline hydrochloride methanolate, C17H15ON2 Cl·½CH3OH, M r = 314.78, has been determined from X-ray diffraction data. The crystals are monoclinic, space group C2/c, with Z = 8 molecules per unit cell and a = 18.179(11), b = 7.317(5), c = 24.125(15) Å, β = 110.155(10)°, V c = 3012(3) Å3, crystal density D c = 1.388 Mg m−3. The structure was solved by direct methods, and the asymmetric unit comprises the 5-N-hydroxyethanequindoline hydrochloride and ½CH3OH moiety. The methanol is unusually disordered over a twofold axis with the C atom slightly removed from the twofold axis. Restraints were applied to the bond lengths of the two components of the disordered CH3OH, and to the anisotropic thermal displacement parameters of the disordered CH3OH carbon atom. The heterocyclic quindoline ring system and the first C atom of the hydroxyethane side chain are planar within 0.02 Å, with the terminal C–OH atoms of the side chain significantly out of the plane. The crystal structure is maintained via three hydrogen bonds all involving the chlorine atom an oxygen in the hydroxyethane side chain, a nitrogen in the quindoline moiety and the methanol oxygen.