Bis[bis(1H-benzimidazol-2-ylmethyl)amine]copper(II) dichloride methanol disolvate dihydrate

In the title compound, [Cu(C16H14N5)2]Cl2·2CH4O·2H2O, the cationic metal complex resides on a crystallographic centre of inversion, with the Cu2+ bonded to two bis(1H-benzimidazol-2-ylmethyl)amines (IDB). The coordination geometry of the Cu2+ ion is distorted octahedral with an N6 ligand set. A three-dimensional framework structure is formed by means of hydrogen bonds and π–π interactions formed between imidazole and phenyl rings, and between phenyl and phenyl rings, with centroid-to-centroid distances of 3.690 (2)–3.977 (2) Å and interplanar spacings of 3.445 (2)–3.502 (2) Å.

The main geometric parameters of (I) are listed in Table 1, and the molecule structure is illustrated in Fig. 1. In (I), the Cu atom displays a distorted octahedral coordination geometry provided by two tridentate IDB ligands: one amine N atom and one benzimidazolyl N atom of each ligand make up the equatorial plane and another benzimidazolyl N atom of each ligand occupies the axial position. As shown in Table 2 and Fig. 2, the molecules are stablized by intermolecular Cl···H-N, Cl···H-O and O···H-N hydrogen bonds and π···π stacking, leading to the formation of a three dimension network.

S2. Experimental
All reagents and solvents were used as obtained without further purification. Bis(benzimidazol-2-yl-methyl)amine (IDB) was prepared according to the method described by Adams et al. (1990). Compound (I) was synthesized by reaction of IDB (0.54 g, 2 mmol) and copper(II) chloride dihydrate (0.17 g, 1 mmol) in methanol (40 ml) at 333 K for 8 h. The resulting solution was filtered and purple crystals of (I) suitable for X-ray diffraction were obtained by slow evaporation of the filtrate at room temperature after one week (yield 55%).

S3. Refinement
All H atoms bonded to C atoms were placed in calculated positions and constrained to ride on their parent atoms, with C -H distances in the range 0.93-0.97 Å, with U iso (H) = 1.2U eq (C). H atoms bonded to N atoms were located in a difference map and were refined with distance restraints of N-H = 0.86 (1)Å and U iso (H) = 1.2U eq (N). Similarly located water H atoms were refined with distance restraints of O-H = 0.82 (1) Å, H···H = 1.35 (1)Å and U iso (H) = 1.5U eq (O).
During the refinement of the structure, electron-density peaks were located that were believed to be highly disordered solvent molecule molecules (possibly methanol and water solvent). Attempts made to model the solvent molecules were not successful. The SQUEEZE option in PLATON (Spek, 2003) indicated there was a solvent cavity of volume 209 Å 3 containing approximately 18 electrons. In the final cycles of refinement, this contribution to the electron density was removed from the observed data. The density, the F(000) value, the molecular weight and the formula are given without taking into account the results obtained with the SQUEEZE option PLATON (Spek, 2003). Similar treatment of disordered solvent molecules were carried out by Suresh et al. (2006, and references therein

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.