Aqua(2,2′-bipyridine-κ2 N,N′){(E)-[(5-chloro-2-oxidobenzylidene)amino-κ2 N,O]methanesulfonato-κO}zinc

In the title compound, [Zn(C8H6ClNO4S)(C10H8N2)(H2O)], the ZnII atom is six-coordinated by two O atoms and one N atom from a tridentate Schiff base ligand and two N atoms from a chelating 2,2′-bipyridine ligand and one water molecule, forming a slightly distorted octahedral geometry. In the crystal, O—H⋯O hydrogen bonds link pairs of complex molecules into dimers. An intramolecular O—H⋯O hydrogen bond is also present.

In the title compound, [Zn(C 8 H 6 ClNO 4 S)(C 10 H 8 N 2 )(H 2 O)], the Zn II atom is six-coordinated by two O atoms and one N atom from a tridentate Schiff base ligand and two N atoms from a chelating 2,2 0 -bipyridine ligand and one water molecule, forming a slightly distorted octahedral geometry. In the crystal, O-HÁ Á ÁO hydrogen bonds link pairs of complex molecules into dimers. An intramolecular O-HÁ Á ÁO hydrogen bond is also present.
Data collection: SMART (Bruker, 2007); cell refinement: SAINT (Bruker, 2007); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL. Zn(CH 3 CO 2 ) 2 .4H 2 O as well as 2,2′-bipyridine. In the title compound, the Zn II atom forms one five-membered and one sixmembered chelating rings with the Schiff base ligand (Fig. 1). The coordinating environment of the Zn II atom is different from that reported by He et al. (2007) and Xu et al. (2007). The bond length of Zn-O(sulfonate) is longer than that of Zn -O(aqua) and also longer than that of Zn-N(imine). It indicates that the coordinating capability of the sulfonate group is weaker than that of water and imine group. In the crystal, O-H···O hydrogen bonds link two complex molecules into a dimer (Table 1). An intramolecular O-H···O hydrogen bond is also present.

Experimental
The complex was prepared by mixing a methanol-water solution of 5-chlorosalicylaldelyde (1.0 mmol), aminomethanesulfonic acid (1.0 mmol) and potassium hydrate (1.0 mmol) with heating and stirring. After 2 h, an aqueous solution containing zinc acetate (1 mmol) was added dropwise under stirring. The pH value of the mixture was adjusted to 6 with 0.5 mol/L HCl solution, followed by the dropwise addition of a methanol solution containing 2,2′-bipyridine (1 mmol) with stirring. The resulting yellow filtrate was allowed to stand at room temperature and slowly evaporate for one month to afforded yellow block-shaped crystals.

Refinement
H atoms attached to C atoms were positioned geometrically and refined as riding atoms, with C-H = 0.93 (CH) and 0.97 (CH 2 ) Å and with U iso (H) = 1.2U eq (C). The water H atoms were located from a difference Fourier map, one of them was refined isotropically and the other was refind as riding, with U iso (H) = 1.5U eq (O).  The molecular structure of the title compound. Displacement ellipsoids are drawn at the 30% probability level. H atoms have been omitted for clarity.

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.