Poly[[2-(3-pyridinio)-1H,3H +-benzimidazolium] [μ4-oxido-di-μ3-oxido-tetra-μ2-oxido-hexaoxidotetramolybdenum(VI)]]

The reaction of MoO3 with 2-(3-pyridyl)benzoimidazole and water in the presence of MnSO4·5H2O at 453 K under hydrothermal conditions afforded the title compound, {(C12H11N2)[Mo4O13]}n, in which infinite molybdenum oxide anionic chains are charge-balanced by diprotonated 2-(3-pyridyl)benzoimidazole (H23-PBIM2+) cations. Eight [MoO6] octahedra are edge-shared, forming compact octamolybdate subunits which are connected through pairs of Mo—O—Mo bridges into extended one-dimensional arrays propagating along the a-axis direction. The asymmetric unit of the metal oxide chain contains one half of the octamolybdate unit, denoted [Mo4O13], the other half being generated by an inversion center. These molybdenum oxide chains are further connected through the 2-(3-pyridinio)benzoimidazolium cations into a three-dimensional network via N—H⋯O hydrogen bonds. In addition, neighbouring diprotonated cations are arranged in a head-to-tail fashion with a plane-to-plane separation of 3.63 (10) Å, indicating the existence of weak aromatic π–π stacking interactions.

The reaction of MoO 3 with 2-(3-pyridyl)benzoimidazole and water in the presence of MnSO 4 Á5H 2 O at 453 K under hydrothermal conditions afforded the title compound, {(C 12 H 11 N 2 )[Mo 4 O 13 ]} n , in which infinite molybdenum oxide anionic chains are charge-balanced by diprotonated 2-(3pyridyl)benzoimidazole (H 2 3-PBIM 2+ ) cations. Eight [MoO 6 ] octahedra are edge-shared, forming compact octamolybdate subunits which are connected through pairs of Mo-O-Mo bridges into extended one-dimensional arrays propagating along the a-axis direction. The asymmetric unit of the metal oxide chain contains one half of the octamolybdate unit, denoted [Mo 4 O 13 ], the other half being generated by an inversion center. These molybdenum oxide chains are further connected through the 2-(3-pyridinio)benzoimidazolium cations into a three-dimensional network via N-HÁ Á ÁO hydrogen bonds. In addition, neighbouring diprotonated cations are arranged in a head-to-tail fashion with a planeto-plane separation of 3.63 (10) Å , indicating the existence of weak aromaticstacking interactions.

Experimental
Crystal data (C 12  metal-organic compounds Table 2 Hydrogen-bond geometry (Å , ). Data collection: CrystalClear (Rigaku, 2002); cell refinement: CrystalClear; data reduction: CrystalClear; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008) and DIAMOND (Brandenburg, 1999)'; software used to prepare material for publication: SHELXL97. The exploration of metal oxide-based inorganic-organic hybrid materials is of contemporary interest in the fields of solid state chemistry, not only because of their fascinating properties and potential applications in many fields, such as catalysis, sorption, electrical conductivity, magnetism and optical materials (Pope & Müller, 1991, Pope, 1983. Owing to their versatile stoichiometry, different structure, and high reactivity (Kong, 2004), molybdenum polyoxoanions are good candidates to function as building blocks for inorganic-organic hybrid materials. Through exploiting the strategy of synergistic interaction between organic and inorganic components, many examples of molybdenum oxide-based solid materials with one-dimensional chain, two-dimensional sheet and three-dimensional framework structures have been successfully synthesized (Hagrman et al., 1999, Lu et al., 2002. The organic components often function as charge compensating cations or as a linking bridges, to extend the molybdenum oxide building units into multi-dimensional networks. We report here the synthesis and crystal structure of the title compound, in which the organic component acts as a charge compensating cation. The structure of title compound consists of an infinite molybdenum oxide chain which is charge balanced by diprotonated H 2 3-PBIM 2+ cations. As shown Fig  In the solid state of the title compound, the one-dimensional molybdenum oxide chains are held together and extended to three-dimensional framework via strong N-H···O hydrogen bonding and weak aromatic π-π stacking interactions. As ligands along the a-direction are arranged in a head-to-tail fashion with a plane-to-plane separation of 3.63 (10) Å, indicating the existence of weak aromatic π-π stacking interactions (Janiak, 2000).

S2. Experimental
A mixture of MoO 3 , MnSO 4 .5H 2 O, 2-(3-pyridyl)benzoimidazole and H 2 O in the molar ratio 1.0:1.2:1.0:1835 was sealed in a 18 ml Teflon-lined Parr acid digestion bomb and heated for 3 days at 453 K and autogeneous pressure. After allowing the reaction mixture to cool down to room temperature, colorless needle-like crystals of title compound were collected, washed with water and air dried.

S3. Refinement
The positions of all hydrogen atoms were generated geometrically (C-H and N-H bonds fixed at 0.96 Å and 0.86 Å, respectively), assigned isotropic thermal parameters, and allowed to ride on their respective parent C or N atoms before the final cycle of least-squares refinement.     Packing diagram of title compound along a axis. Broken lines indicate hydrogen bonds. All H atoms, which do not participate in the bydrogen bonds, have been omitted for clarity.

Poly[[2-(3-pyridinio)-1H,3H + -benzimidazolium] [µ 4 -oxido-di-µ 3 -oxido-tetra-µ 2 -oxidohexaoxidotetramolybdenum(VI)]]
Crystal data (C 12  where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max = 0.001 Δρ max = 0.98 e Å −3 Δρ min = −1.14 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.