trans-Diamminedichloridobis(1H-imidazole-κN 3)nickel(II)

The whole molecule of the title compound, [NiCl2(C3H4N2)2(NH3)2], is generated by inversion symmetry. The NiII ion, which is located on an inversion center, has a distorted octahedral coordination environment and is surrounded by two ammine N atoms and two Cl atoms in the equatorial plane, with two N atoms of two imidazole groups occupying the axial positions. The imidazole ring makes a dihedral angle of 81.78 (18)° with the Ni/N/Cl equatorial plane. In the crystal, molecules are linked via N—H⋯Cl hydrogen bonds and C—H⋯π interactions, forming a three-dimensional network.

The chemistry of imidazole occupies an extremely important position within the family of five-membered heterocyclic compounds. Synthesis of imidazole derivatives has attracted great interest in recent years due to their broad spectrum of biological activities (Gaonkar et al., 2009). Herein we report on the crystal structure of the title compound.
The molecular structure of the title compound as illustrated in Fig In the crystal, molecules are linked via N-H···Cl hydrogen bonds and C-H···π interactions forming a three-dimensional network (Table 1 and Fig. 2).

Experimental
A total of 10 mL of a 0.01 M aqueous solution of NiCl 2 was slowly mixed with 20 mL of a 0.02 M ammonia solution.
After 1 h, 20 mL of a 0.02 M aqueous solution of imidazole was added drop wise. The mixture was slowly evaporated at room temperature, and deep-green block-like crystals of the title complex were obtained within 5 days. The crystals were filtered, washed with water, and dried in a desiccator over P 4 O 10 .

Refinement
All the H atoms were fixed geometrically and allowed to ride on their parent N or C atoms: N-H = 0.86 and 0.89 Å for NH and NH 3 H atoms, respectively, C-H = 0.93-0.97 Å; U iso (H) = 1.5U eq (C-methyl) and = 1.2U eq (N,C) for other H atoms.

Figure 2
The crystal packing of the title compound viewed along the c axis. Dashed lines show the N-H···Cl hydrogen bonds [see

trans-Diamminedichloridobis(1H-imidazole-κN 3 )nickel(II)
Crystal data [NiCl 2 (C 3  where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 0.76 e Å −3 Δρ min = −1.00 e Å −3 Special details Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds 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 > 2sigma(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.