Crystal structure of dichloridobis(1,3,4,5-tetramethyl-1H-imidazol-2-ium-2-thiolate-κS)nickel(II)

In the molecular structure of the title compound, [NiCl2(C7H12N2S)2], the NiII atom has a distorted tetrahedral geometry, coordinated by two Cl atoms [Ni—Cl= 2.2336 (6) Å] and two thione S atoms [Ni—S= 2.3024 (6) Å]. The angles at the NiII cation, which lies on a twofold rotation axis, are Cl—Ni—Cl = 115.58 (3)° and S—Ni—S = 94.55 (3)°. All other angles at the central NiII atom range from 109.46 (2) to 112.96 (2)°. The C—S—Ni angle is 99.91 (6)°. The planes of two imidazolium rings make a dihedral angle of 70.56 (6)°.

Supporting information for this paper is available from the IUCr electronic archives (Reference: HP2071).

S1. Structural commentary
We are interested in the chemistry of N,N-dimethylimidazole-thione derivatives due to their ability to act as effective  (6) Å. The C-S bond length in the title compound is elongated to 1.719 (2)Å by coordination to Nickel and closer to a single bond 1.81Å than a double bond 1.56Å (Williams et al., 1997). The intramolecular hydrogen bonds between the chlorine atom and hydrogen atoms of methyl group, H2a--Cl and H7b--Cl amount to 3.093 and 3.557.respectively.

S2. Synthesis and crystallization
To a solution of 1,3,4,5-tetra-methylimidazoline-2-thione (0.390mg, 2.75mmol) in 40 ml acetonitrile, NiCl 2 (0.162 mg, 1.25 mmol) ) was added and the mixture was stirred at room temperature for 24h. After removal of the solvent and subsequent drying in vacuum the residue was crystallized by diffusion of diethyl ether into a concentrated acetonitrile solution to give green single-crystals of the title complex.

S3. Refinement
Crystal data, data collection and structure refinement details are summarized in Table 1. All H-atoms were clearly identified in difference syntheses and then refined at idealized positions riding on the carbon atoms with isotropic displacement parameters Uiso(H) = 1.5U(-CH 3 ) and C-H 0.98 Å. All CH 3 hydrogen atoms were allowed to rotate but not to tip.

Figure 1
Molecular structure of the title compound with anisotropic displacement parameters drawn at the 50% probability level.

Dichloridobis(1,3,4,5-tetramethyl-1H-imidazol-2-ium-2-thiolate-κS)nickel(II)
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.