X-ray crystal structure investigation of an N-substituted ciprofloxacin:1-cyclopropyl-6-fluoro-1,4-dihydro-7-[4-(1-isovaleramido- 1-trifluoromethyl-2,2,2-trifluoroethyl)-1-piperazinyl]-4-oxoquinoline- 3-carboxylic acid

The x-ray crystal and molecular structure of an N-substituted ciprofloxacinC25H27F7N4O4(I) was determined: sp. gr. P21/c; a=9.870(1); b=28.443(3), and c=9.534(1) A; β=99.09(1) deg., Z=4; and R=0.046 [automated CAD-4 diffractometer,λCuKα; 2687 unique reflections with I≥2σ]. Molecule I contains a flattened bicyclic 1,4-dihydro-4-oxoquinoline skeleton and a COOH group coplanar to it, which forms a strong intramolecular hydrogen bond with the 4-oxo group. The piperazine ring in I has a chair conformation, and the plane through its four C atoms forms an angle of 37 deg. with the plane through the adjacent benzene ring. Two unusual intramolecular hydrogen bonds are observed in the structure: C(sp3)-H···F-C(ar) and N(sp2)-H···F-C(sp3). In the crystal, molecules I are connected by the intermolecular hydrogen bonds ···O=C-N-H···O=C-N-H···etc., into infinite chains running along the z-axis