catena-Poly[(trans-diaquacadmium)-bis{μ-5-[4-(1H-imidazol-1-yl)phenyl]tetrazol-1-ido}]

In the title compound, [Cd(C10H7N6)2(H2O)2], the CdII atom lies on an inversion centre and is coordinated by four N atoms from 5-[4-(1H-imidazol-1-yl)phenyl]tetrazol-1-ide ligands and two O atoms from the coordinated water molecules in an octahedral arrangement. The complex polymeric chains are interconnected via intermolecular water O—H⋯N hydrogen bonds into a three-dimensional network.

In the title compound, [Cd(C 10 H 7 N 6 ) 2 (H 2 O) 2 ], the Cd II atom lies on an inversion centre and is coordinated by four N atoms from 5-[4-(1H-imidazol-1-yl)phenyl]tetrazol-1-ide ligands and two O atoms from the coordinated water molecules in an octahedral arrangement. The complex polymeric chains are interconnected via intermolecular water O-HÁ Á ÁN hydrogen bonds into a three-dimensional network.

Comment
The ligands having more N atoms can be used to synthesize complexes of variety of cordination modes. Our research group has show great interest in the metal-organic complexes with imidazole and tetrazole derivatives, such as 2-propylimidazole-4,5-dicarboxylic acid (Tong, Li et al., 2011;Li et al., 2010) and 1-tetrazole-4-imidazolebenzene. In this paper, we report the synthesis and structure of a new Cd II complex, [Cd(C 8 H 9 N 2 O 4 ) 4 (H 2 O) 2 ] n obtained under hydrothermal conditions. An asymmmetric unit of the title complex molecule includes one Cd II , 1-tetrazole-4-imidazolebenzene ligand and a coordinated water molecule (Fig. 1). The Cd II atom is octahedrally coordinated and lies on an inversion centre, connected with four ligands [two imidazole N and two tetrazole N, Cd-N =2.264 (2) and 2.385 (2) Å] and two coordinated water molecules [Cd-O=2.461 (2) Å] ( Table 1) (Table 2). For related structures of complexes with this ligand, see Huang et al. (2009) andCheng (2011).

Experimental
A mixture of cadmium nitrate (0.1 mmol, 0.020 g) and 1-tetrazole-4-imidazole-benzene (0.2 mmol, 0.043 g) in 12 mL of water and 3 mL of alcohol was sealed in an autoclave equipped with a Teflon liner (25 mL) and then heated at 413 K for 3 days. Crystals of the title compound were obtained by slow evaporation of the solvent at room temperature.

Refinement
H atoms of the water molecule were located in a difference-Fourier map and refined as riding with an O-H distance restraint of 0.85 Å, with U iso (H) = 1.5 U eq . The imidazolyl and phenyl H atoms were located in a difference-Fourier but were refined as riding with C-H = 0.93 Å and U iso (H) = 1.5U eq (C).

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.