Diaquabis(2-ethyl-5-methylimidazole-4-sulfonato-κ2 N 3,O)nickel(II) dihydrate

In the title complex, [Ni(C6H9N2O3S)2(H2O)2]·2H2O, the NiII atom lies on an inversion center and is chelated by N and O atoms of two symmetry-equivalent imidazolesulfonate ligands in the basal plane, and two water O atoms in axial positions in an overall octahedral configuration. The crystal structure displays O—H⋯O and N—H⋯O hydrogen bonds, which connect the components into an extended three-dimensional network.

In the title complex, [Ni(C 6 H 9 N 2 O 3 S) 2 (H 2 O) 2 ]Á2H 2 O, the Ni II atom lies on an inversion center and is chelated by N and O atoms of two symmetry-equivalent imidazolesulfonate ligands in the basal plane, and two water O atoms in axial positions in an overall octahedral configuration. The crystal structure displays O-HÁ Á ÁO and N-HÁ Á ÁO hydrogen bonds, which connect the components into an extended three-dimensional network.

Experimental
A solution of the potassium salt of the 2-ethyl-4-methyl-imidazole-5-sulfonic acid was prepared by combining 1 g (5.25 mmol) of the free acid with 1.5 equivalents of KOH solution, and diluting the solution to 1M based on K + . (All solutions were made with distilled water.) Two test reactions were done in vials with 0.5 M solutions of Ni(BF 4 ) 2 ·6H 2 O and MnSO 4 ·H 2 O, a 0.2 ml metered pipet was used for the additions, and each vial contained one addition of all three solutions. After 1 month, one vial were heated to a boil and allowed to cool and the other remained at room temperature.
After one year, large blue crystals of the title compound grew in the solution that was not heated.

Computing details
Data collection: CrysAlis PRO (Agilent, 2012); cell refinement: CrysAlis PRO (Agilent, 2012)   Packing diagram viewed down the c axis, displaying the hydrogen bonded interactions of both the coordinated and uncoordinated water molecules.

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.