Crystal structure of (RS)-4-(3-carb­oxy-1-ethyl-6,8-di­fluoro-4-oxo-1,4-di­hydro­quinolin-7-yl)-2-methyl­piperazin-1-ium 3-carb­oxy-5-fluoro­benzoate

In the title organic salt, C(17)H(20)F(2)N(3)O(3) (+)·C(8)H(4)FO(4) (−), proton transfer leads to one protonated lomefloxacin mol­ecule (HLf(+)) and one 3-carb­oxy-5-fluoro­benzoate (5-F-Hip(−)) anion in the asymmetric unit. The HLf(+) cation is bent, with a dihedral angle of 38.3 (1)° between the quinoline ring and the piperazinium moiety. In the crystal, two kinds of N—H⋯O and O—H⋯O hydrogen-bonded chains cross-link each other to produce a three-dimensional network structure that is additionally stabilized by weak C—H⋯O and C—H⋯F hydrogen bonds, as well as π–π inter­actions. The methyl group attached to the piperazinium ring is disordered over two sets of sites [refined ratio: 0.645 (5):0.335 (5)], indicating the presence of both enanti­omers of the cation in the structure.