Diaquabis{1-[(1H-benzimidazol-2-yl)methyl]-1H-imidazole-κN 3}dichloridocadmium hexahydrate

In the title complex, [CdCl2(C11H10N4)2(H2O)2]·6H2O, the CdII atom is located on a twofold rotation axis and is coordinated by two N atoms from two 1-[(1H-benzimidazol-2-yl)methyl]-1H-imidazole ligands and two water O atoms in equatorial positions and by two Cl atoms in axial positions, leading to an elongated octahedral environment. The two coordinating and two of the lattice water molecules are also located on twofold rotation axes. In the crystal, complex molecules and solvent water molecules are linked through a complex intermolecular N—H⋯O, O—H⋯N, O—H⋯O and O—H⋯Cl hydrogen-bonding scheme into a three-dimensional network.

In the title complex, [CdCl 2 (C 11 H 10 N 4 ) 2 (H 2 O) 2 ]Á6H 2 O, the Cd II atom is located on a twofold rotation axis and is coordinated by two N atoms from two 1-[(1H-benzimidazol-2yl)methyl]-1H-imidazole ligands and two water O atoms in equatorial positions and by two Cl atoms in axial positions, leading to an elongated octahedral environment. The two coordinating and two of the lattice water molecules are also located on twofold rotation axes. In the crystal, complex molecules and solvent water molecules are linked through a complex intermolecular N-HÁ Á ÁO, O-HÁ Á ÁN, O-HÁ Á ÁO and O-HÁ Á ÁCl hydrogen-bonding scheme into a threedimensional network.

Related literature
For background information on Cd II complexes constructed from N-heterocyclic ligands see: Jin et al. (2012); Liu et al. (2008).
Colourless crystals were obtained from the filtrate and dried in air.

Refinement
H atoms bound to C and N atoms were positioned geometrically and refined as riding atoms, with C-H = 0.93 (aromatic) Å and 0.97 (CH 2 ) Å, N-H = 0.86 Å. H atoms bound to O atoms were found from difference maps and refined with distance restraints of O-H = 0.85 Å. All H atoms were refined with U iso (H) = 1.2 U eq (C,N,O).

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