catena-Poly[[[2-(2-pyridyl)-1H-benzimidazole]cadmium(II)]-μ-benzene-1,4-dicarboxylato]

In the title compound, [Cd(C8H4O4)(C12H9N3)]n, each CdII ion is six-coordinated in a distorted octahedral geometry by four carboxylate O atoms from two benzene-1,4-dicarboxylate anions (L), and two N atoms from one 2-(2-pyridyl)benzimidazole ligand. The neighboring CdII ions are bridged by the L ligands, forming a zigzag polymeric chain structure. The chains are further extended into a three-dimensional supramolecular structure through intermolecular N—H⋯O hydrogen bonds.

In the title compound, [Cd(C 8 H 4 O 4 )(C 12 H 9 N 3 )] n , each Cd II ion is six-coordinated in a distorted octahedral geometry by four carboxylate O atoms from two benzene-1,4-dicarboxylate anions (L), and two N atoms from one 2-(2-pyridyl)benzimidazole ligand. The neighboring Cd II ions are bridged by the L ligands, forming a zigzag polymeric chain structure. The chains are further extended into a three-dimensional supramolecular structure through intermolecular N-HÁ Á ÁO hydrogen bonds.
Selected bond distances are listed in Table 1. Each Cd II center is six-coordinated by two N atoms of the chelating PyBM ligand and four O atoms from two L ions. The neighboring Cd II ions are bridged by L ligands to form a zigzag polymeric chain structure (Fig. 2).
In the crystal structure, the adjacent chains are linked via N-H···O hydrogen bonds (Table 2) resulting in the formation of a three-dimensional supramolecular structure.

S3. Refinement
The H atom bonded to atom N3 was located in a difference map and refined with the N-H distance restrained to 0.85 (2) Å. C-bound H atoms were positioned geometrically (C-H = 0.93 Å) and refined as riding, with U iso (H) = 1.2U eq (C).  The coordination environment of the Cd II ion in the title compound, showing the atom-numbering scheme. Displacement ellipsoids are drawn at the 30% probability level. Symmetry code: (i) 1 + x, 1/2 -y, 1/2 + z.

Figure 2
Part of the polymeric chain in the title compound.

catena-Poly[[[2-(2-pyridyl)-1H-benzimidazole]cadmium(II)]-µ-benzene-1,4-dicarboxylato]
Crystal data 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