Bis(dihydrogen norfloxacinium) tri-μ2-chlorido-bis[trichloridobismuthate(III)] chloride dihydrate

The title compound, {systematic name: (3-carboxy-1-ethyl-6-fluoro-7-piperazin-4-ium-1-yl-1H-quinolin-4-ylidene)oxonium tri-μ2-chlorido-bis[trichloridobismuthate(III)] chloride dihydrate], (C16H20FN3O3)2[Bi2Cl9]Cl·2H2O, is composed of [Bi2Cl9]3− anions lying on crystallographic twofold rotation axes, Cl− anions also on twofold axes, C16H20FN3O3 2+ cations, and water molecules. The BiIII coordination polyhedron is a distorted octahedron and two such octahedra share a triangular face to form the complex anion. There are three short terminal Bi—Cl bonds [2.5471 (6)–2.5781(5 Å] and three longer bridging bonds [2.8599 (5)–2.9984 (6) Å] in each octahedron. Anions, cations and water molecules are linked by hydrogen bonds to form a three-dimensional network. There are also π–π stacking interactions between quinoline ring systems, with an interplanar distance of 3.27 (1) Å.


Related literature
For the Cambridge Structural Database (Version 5.28) used to identify related structures, see: Allen (2002).
The asymmetric unit of the title compound, (I), contains one Bi atom, five chlorine atoms, one nfH 3 cation and one H 2 O molecule. The Bi atoms are coordinated by six Cl atoms in a distorted octahedral geometry. Two Bi-centred octahedra are linked by triple Cl bridges to form a dinuclear [Bi 2 Cl 9 ] 3complex ( Fig. 1), which lies on a twofold rotation axis, with a The protonation of nfH 3 2+ is realised on the carbonyl atom O3 and N3 of the piperazine ring (Fig. 2). The hydrogen atom H3 is linked by an intramolecular hydrogen bond with O1 of the carboxyl group. O2 and N3 in the cation act as hydrogen-bond donors, via H2, H3A and H3B.
Water molecules, uncoordinated chloride anions (Cl6) and nfH 3 2+ cations are linked in zigzag chains by hydrogen bonds parallel to the [102] direction (Fig. 3). In the chain, the nfH 3 2+ cations are pairwise parallel (as a result of inversion symmetry), and there exist also π-π interactions between quinoline ring systems, with an interplanar distance of 3.27 (1) Å.
The combination of the hydrogen bonds and π-π stacking generates a three-dimensional network (Fig. 4).
Yellow crystals were obtained after evaporation for 72 h at room temperature.

S3. Refinement
H atoms (for H 2 O) were located in a difference map and refined with U iso (H) = 1.5U eq (O) and the O-H distances were restrained to be similar. The other H atoms were positioned with idealized geometry using a riding model with C-H = 0.94, 0.97 and 0.98 Å; N-H = 0.91 Å and O-H = 0.83 Å. All H atoms were refined with U iso set to 1.2 or 1.5 times U eq of the parent atom. The maximum peak and the deepest hole are located 0.77 Å and 1.33 Å from Bi, respectively.    Fragment of the zigzag chain formed from water molecules, chloride anions and nfH 3 2+ canions, with hydrogen bonds shown as dashed lines.

Figure 4
The crystal structure of the title compound viewed along the c axis. Dashed lines represent hydrogen bonds.
(3-carboxy-1-ethyl-6-fluoro-7-piperazin-4-ium-1-yl-1H-quinolin-4-ylidene)oxonium tri-µ 2 -chlorido-  (17) Special details Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes. Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.