Enrofloxacin hydrochloride dihydrate

Abstract

The asymmetric unit of the title compound, C19H23FN3O3+·Cl−·2H2O [systematic name: 4-(3-carboxy-1-cyclopropyl-6-fluoro-4-oxo-1,4-dihydroquinolin-7-yl)-1-ethylpiperazin-1-ium chloride dihydrate], consists of two independent monocations of the protonated enrofloxacin, two chloride anions and four water molecules. In the cations, the piperazinium rings adopt chair conformations and the dihedral angles between the cyclopropyl ring and the 10-membered quinoline ring system are 56.55 (2) and 51.11 (2)°. An intramolecular O—H...O hydrogen bond is observed in each cation. In the crystal, the components are connected via O—H...Cl, N—H...Cl and O—H...O hydrogen bonds, and a π–π interaction between the benzene rings [centroid–centroid distance = 3.6726 (13) Å], resulting in a three-dimensional array.