2-(3-Pyridinio)benzimidazolium pentachloridobismuthate(III) monohydrate

In the title compound, (C12H11N3)[BiCl5]·H2O, the BiIII atom is coordinated by five chloride anions in a distorted square-pyramidal geometry. The planar imidazole ring system [maximum deviation = 0.012 (3) Å] is oriented at a dihedral angle of 6.08 (5)° with respect to the protonated pyridine ring. An O—H⋯Cl interaction links the water molecule to the dianion. In the crystal structure, intermolecular O—H⋯Cl, N—H⋯O and N—H⋯Cl interactions link the molecules into a three-dimensional network.

In the title compound, (C 12 H 11 N 3 )[BiCl 5 ]ÁH 2 O, the Bi III atom is coordinated by five chloride anions in a distorted squarepyramidal geometry. The planar imidazole ring system [maximum deviation = 0.012 (3) Å ] is oriented at a dihedral angle of 6.08 (5) with respect to the protonated pyridine ring. An O-HÁ Á ÁCl interaction links the water molecule to the dianion. In the crystal structure, intermolecular O-HÁ Á ÁCl, N-HÁ Á ÁO and N-HÁ Á ÁCl interactions link the molecules into a three-dimensional network.
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: HK2717). Bismuthate(III) compounds have received great attention owing to their anti-ulcer activity (Turel et al., 1998) and their unique optical and electronic properties, including nonlinear optical activity, luminescence and semiconductivity (Goforth et al., 2004). We report herein the crystal structure of the title compound.
The asymmetric unit of the title compound, (Fig. 1), contains a 2-(3′-pyridinio)benzimidazolium dication, a pentachlorobismuthate dianion and a water molecule. In the dianion, the bismuth (III) atom is coordinated by five chloride anions in a distorted square-pyramidal geometry. The Bi-Cl distances are in the range of 2.519 (3)-2.787 (3) Å. In the dication, the planar imidazole ring system [with maximum deviation of 0.012 (3) Å for atom C3] is oriented with respect to the pyridine ring at a dihedral angle of 6.08 (5)°. Intramolecular O-H···Cl interaction links the water molecule to the dianion (Table 1).
In the crystal structure, intramolecular O-H···Cl and intermolecular N-H···O and N-H···Cl interactions (Table 1) link the molecules into a three-dimensional network (Fig. 2), in which they may be effective in the stabilization of the structure.

S2. Experimental
For the preparation of the title compound, concentrated hydrochloric acid (12 M) was added dropwise to a mixture of 2-(3-pyridinio)benzimidazole (0.1 mmol) and water (7 ml), until complete dissolution of the solid phase. Concentrated hydrochloric acid was similarly added dropwise to dissolve the solid phase persisting in a mixture of bismuth chloride (0.3 mmol) and water (5 ml). The two solutions were then mixed and stirred for 20 min. The resulting precipitate was filtered off and dissolved in hydrochloric acid. Colorless crystals suitable for X-ray analysis were obtained after several weeks by slow evaporation of the solvent at room temperature.  The molecular structure of the title molecule, with the atom-numbering scheme. Displacement ellipsoids are drawn at the 30% probability level

2-(3-Pyridinio)benzimidazolium pentachloridobismuthate(III) monohydrate
Crystal data (C 12  where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 1.28 e Å −3 Δρ min = −2.37 e Å −3 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.