Tetraaquabis(N-phenylsulfonyl-l-leucinato)cadmium(II) dihydrate

In the title compound, [Cd(C12H16NO4S)2(H2O)]·2H2O, the Cd atom is located on a twofold rotation axis and a distorted CdO8 dodecahedral arrangement arises from the coordination of the two chelating ligands and four water molecules. A network of N—H⋯O, O—H⋯O and C—H⋯O hydrogen bonds help to establish the crystal packing. Both coordinated and uncoordinated water molecules are disordered with an approximate half-occupation for each of the water molecules.

In the title compound, [Cd(C 12 H 16 NO 4 S) 2 (H 2 O)]Á2H 2 O, the Cd atom is located on a twofold rotation axis and a distorted CdO 8 dodecahedral arrangement arises from the coordination of the two chelating ligands and four water molecules. A network of N-HÁ Á ÁO, O-HÁ Á ÁO and C-HÁ Á ÁO hydrogen bonds help to establish the crystal packing. Both coordinated and uncoordinated water molecules are disordered with an approximate half-occupation for each of the water molecules.

Related literature
For background to the design and synthesis of metal complexes, see: Zhang et al. (2007).
The author thanks the National Natural Science Foundation of China (20671073), the Natural Science Foundation of Shandong (Y2007B60) and Weifang University for research grants.

S1. Comment
During the last decade, the design and synthesis of metal complexes have attracted considerable attention due to their potential uses as biological activities (Zhang et al., 2007). The synthesis and structure of the title compound (I) is reported.
Two molecules of water complete the structure of (I) and a network of hydrogen bonds helps to establish the crystal packing (Table 1).

S2. Experimental
1 mmol of cadmium chloride was added to a solution of 2-phenylsulfonyl chloride-L-leucine (2 mmol) in 10 ml of CH 3 OH/H 2 O (v/v 1:1). The mixture was continuously stirred for 4 h at refluxing temperature, evaporating some methanol, then, upon cooling, the solid product was collected by filtration and dried in vacuo (yield 69%). Clear blocks of (I) were obtained by evaporation from a methanol solution after a week.

S3. Refinement
The water H atoms were located in a difference map and refined as riding in their as-found relative positions with U iso (  The complex molecule, with 30% probabiility ellipsoids.  where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max = 0.001 Δρ max = 0.70 e Å −3 Δρ min = −0.56 e Å −3 Absolute structure: Flack (1983), 1247 Freidel pairs Absolute structure parameter: 0.00 (8) 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.