1-(5-Carboxy-pent-yl)-2,3,3-trimethyl-3H-indol-1-ium bromide monohydrate.

Abstract

In the title compound, C17H24NO2 +·Br−·H2O, the pentyl group chain in the cation extends nearly perpendicular [N—C—C—C = −64.4 (3)°] to the mean plane of the indole ring with the carboxyl end group twisted such that the dihedral angle between the mean planes of the indole and carb­oxy groups measures 43.2 (4)°. Both ions in the salt form inter­molecular hydrogen bonds (O—H⋯Br and O—H⋯O) with the water mol­ecule. As a result of the Br⋯H—O—H⋯Br inter­actions, a zigzag chain is formed in the c-axis direction. The crystal packing is influenced by the collective action of the O—H⋯O and O—H⋯Br inter­molecular inter­actions as well as π–π stacking inter­molecular inter­actions between adjacent benzyl rings of the indole group [centroid–centroid distance = 3.721 (13) Å] and inter­molecular C—H⋯π inter­actions between a methyl hydrogen and the benzyl ring of the indole group. The O—H⋯Br inter­actions form a distorted tetra­hedral array about the central Br atom. A MOPAC AM1 calculation provides support to these observations.