Tetrakis(dihydrogen pefloxacinium) di-μ2-chlorido-bis[tetrachloridobismuthate(III)] tetrachloride octahydrate

The title compound {systematic name: tetrakis[4-(3-carboxy-1-ethyl-6-fluoro-4-hydroxonio-1,4-dihydro-7-quinolyl)-1-methylpiperazin-1-ium] di-μ2-chlorido-bis[tetrachloridobismuthate(III)] tetrachloride octahydrate}, (C17H22FN3O3)4[Bi2Cl10]Cl4·8H2O, is composed of edge-shared centrosymmetric dinuclear [Bi2Cl10]4− anions, Cl− anions, dihydrogen pefloxacinium cations and water molecules. The BiIII coordination polyhedron is a distorted octahedron. There are four short terminal Bi—Cl bonds [2.5037 (10)–2.6911 (7) Å] and two longer bridging bonds [2.8834 (8) and 3.0687 (9) Å] in each octahedron. Two sets of chloride ions and water molecules are disordered over the same sites with site occupancies of 1/3 and 2/3, respectively. Anions, cations and water molecules are linked by O—H⋯O, O—H⋯Cl and N—H⋯Cl hydrogen bonds, forming a three-dimensional framework. There are also π–π stacking interactions between quinoline ring systems [centroid–centroid distance = 3.575 (1) Å].


Related literature
For a description of the Cambridge Structural Database, see: Allen (2002).
Data collection: SMART (Bruker, 1998); cell refinement: SAINT (Bruker, 2003); data reduction: SAINT ; program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL ; molecular graphics: XP in SHELXTL; software used to prepare material for publication: publCIF (Westrip, 2008). The protonation of pfH 3 2+ is realised on the carbonyl atom O3 and N2 of the piperazine ring (Fig. 3). The hydrogen atom H3 is linked by an intramolecular hydrogen bond with O1 atom of the carboxyl group. Atoms O2 and N2 in the cation act as hydrogen-bond donors, via H4 and H2 There are three uncoordinated chlorine atoms (Cl5, Cl6 and Cl7) of which Cl6 and Cl7 are disordered and statistically replaced by atoms O6 and O7 of water molecules, respectively [Wyckoff positions 8j and 4i for Cl6/O6 and Cl7/O7, respectively]. Site occupation factors of these chloride ions were assigned equal to 1/3, and water molecule to 2/3 from the crystal chemistry considerations. The refinement of the Cl6/O6 and Cl7/O7 site occupation factors resulted in the same values with accuracy within 0.04. As the hydrogen atoms were not located for disordered water molecules, probable hydrogen bonds involving these atoms are given in Table 3. In the crystal structure, the cations are packed along the aaxis. There exist π-π stacking interactions between quinoline ring systems (Fig.4), with nearest C···C contacts are in the range 3.292 (5)

S2. Experimental
Bi(OH) 3 (1.00 g, 3.85 mmol) was reacted with pfH (1.50 g, 5.77 mmol) in a solution of HCl (35%, 15 ml). Yellow crystals were obtained after evaporation for 72 h at room temperature. All H atoms were refined with U iso set to 1.2 or 1.5 times U eq of the parent atom. Atoms Cl6 and O6, and also Cl7 and O7, are disordered between them with site occupancies of 1/3 and 2/3, respectively. H atoms belonging to the disordered water molecules could not be located. The maximum peak and the deepest hole are located 0.86 Å and 1.13 Å from Bi, respectively.

Figure 2
The crystal structure of the title compound, viewed along the c axis. Dashed lines represent hydrogen bonds.  A view of the pfH 3 2+ canion, with displacement ellipsoids drawn at the 50% probability level. The intramolecular hydrogen bond is shown as a dashed line.

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq Occ. (