Bis(4-aminobenzenesulfonato-κN)diaquabis(dimethylformamide-κO)nickel(II) dihydrate

In the title compound, [Ni(C6H6NO3S)2(C3H7NO)2(H2O)2]·2H2O, the NiII ion (site symmetry ) is coordinated by two –NH2 groups from two 4-aminobenzenesulfonate anions, two O atoms from two dimethylformamide molecules and two water molecules, forming a slightly distorted trans-NiN2O4 octahedral geometry. In the crystal structure, intermolecular O—H⋯O, O—H⋯(O,O) and N—H⋯O hydrogen bonds link the components into a three-dimensional network. The O atoms of the sulfonate group are disordered over two sets of sites in a 0.833 (4):0.167 (4) ratio and the O atom of the uncoordinated water molecule is disordered over two sites in a 0.637 (18):0.363 (18) ratio.

In the title compound, [Ni(C 6 H 6 NO 3 S) 2 (C 3 H 7 NO) 2 (H 2 O) 2 ]Á-2H 2 O, the Ni II ion (site symmetry 1) is coordinated by two -NH 2 groups from two 4-aminobenzenesulfonate anions, two O atoms from two dimethylformamide molecules and two water molecules, forming a slightly distorted trans-NiN 2 O 4 octahedral geometry. In the crystal structure, intermolecular O-HÁ Á ÁO, O-HÁ Á Á(O,O) and N-HÁ Á ÁO hydrogen bonds link the components into a three-dimensional network. The O atoms of the sulfonate group are disordered over two sets of sites in a 0.833 (4):0.167 (4) ratio and the O atom of the uncoordinated water molecule is disordered over two sites in a 0.637 (18):0.363 (18) ratio.
In this paper, we report the structure of the title compound, (I), im which the Ni II ion is located on a crystallographic inversion center and is coordinated by two -NH 2 groups from two 4-aminobenzenesulfonate ligands and four oxygen atoms from two water molecules and two N,N′-dimethylformamide molecules (Table 1 and Fig. 1), forming a slightly distorted octahedral coordination environment.
In the crystal structure, intermolecular O-H···O and N-H···O hydrogen bonds link the title complex into a threedimensional network (Table 2 and Fig.2).

S2. Experimental
An ethanol solution (20 ml) containing nickel chloride (0.237 g, 1 mmol) was added dropwise to an aqueous solution containing 4-aminobenzenesulfonic acid (0.180 g, 1 mmol) and sodium hydroxide (0.040 g, 1 mmol) with stirring over a period of 10 min. The green solid compound was separated out and dissolved in N,N-dimethylformamide, then the green solution was filtrated. After 20 days, green blocks of (I) were produced from the filtrate (yield: 35.3%).

S3. Refinement
The -SO 3 group is disordered over two positions with respect to the O atoms in a 0.83 (1)  The molecular structure of (I), with displacement ellipsoids drawn at the 30% probability level. Unlabelled atoms in the complex are generated by the symmetry operation (1-x, -y, 1-z).  Part of the crystal structure of the title compound showing hydrogen bonds as dashed lines.

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.