Enrofloxacinium oxalate

The title salt, 2C(19)H(23)FN(3)O(3) (+)·C(2)O(4) (2−) {systematic name: bis-[4-(3-carb­oxy-1-cyclo­propyl-6-fluoro-4-oxo-1,4-di­hydro­quino­lin-7-yl)-1-ethyl­piperazin-1-ium] oxalate}, crystallizes with two independent monocations (A and B) and an oxalate dianion (C) in the asymmetric unit. The piperazinium ring in both the cations adopts a slightly disordered chair conformation. The dihedral angles between the mean planes of the cyclo­propyl ring and the 10-membered quinoline ring are 50.6 (5)° (A) and 62.2 (5)° (B). In each of the cations, a single O—H⋯O intra­molecular hydrogen bond is observed. In the crystal, the oxalate anions inter­act with the cations through N—H⋯O hydrogen bonds and weak C—H⋯O inter­actions, forming R (2) (2)(8) graph-set ring motifs. Weak C—H⋯F inter­actions along with further C—H⋯O inter­actions are observed between the cations, forming zigzag chains along [001]. In addition, π–π stacking inter­actions are observed with centroid–centroid distances of 3.5089 (13), 3.5583 (13), 3.7900 (13) and 3.7991 (13) Å.