Bis[2-(2-pyridylmethyleneamino)benzenesulfonato-κ3 N,N′,O]cadmium(II) dihydrate

The title complex, [Cd(Paba)2]·2H2O or [Cd(C12H9N2O3S)2]·2H2O, was synthesized by the reaction of the potassium salt of 2-(2-pyridylmethyleneamino)benzenesulfonic acid (PabaK) with CdCl2·2.5H2O in methanol. The CdII atom lies on a crystallographic twofold axis and is coordinated by four N atoms and two O atoms from two deprotonated tridentate 2-(2-pyridylmethyleneamino)benzenesulfonate ligands in a slightly distorted octahedral environment. There are extensive hydrogen bonds of the type O—H⋯O between the uncoordinated water molecules and the sulfonate O atoms, through which the complex forms a layered structure parallel to (001).

The O-H donor group of the guest waters and the S=O acceptor group of the Paba ligands participate in the hydrogen bonding and form a two-dimensional network in the ab plane (Fig. 2).
For the preparation of the title complex, the ligand PabaK (1 mmol, 0.30 g) was dissolved in methanol (10 ml) at 333 K and an aqueous solution (10 ml) containing CdCl 2 .2.5H 2 O (0.5 mmol, 0.12 g) was added.The resulting mixture was stirred at 333 K for 4 h.Then the mixture was filtrated and the filtrate was left to stand at room temperature.Yellow crystals suitable for X-ray diffraction were obtained after a week in a yield of 35%.Elemental analysis,.found(%): C, 46.91; H, 3.36; N, 8.30; S, 9.45; calc (%): C, 42.96; H, 3.31; N, 8.35; S, 9.56.

S3. Refinement
H atoms bonded to C were positioned geometrically with C-H distance 0.93 Å, and treated as riding atoms,with U iso (H)= 1.2U eq (C).Water hydrogens were placed in fixed positions and assigned U iso values of 1.5 U eq of the water oxygen atom.

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 Rfactors based on ALL data will be even larger.
The title complex, [Cd(Paba) 2 ]Á2H 2 O or [Cd(C 12 H 9 N 2 O 3 S) 2 ]Á-2H 2 O, was synthesized by the reaction of the potassium salt of 2-(2-pyridylmethyleneamino)benzenesulfonic acid (PabaK) with CdCl 2 Á2.5H 2 O in methanol.The Cd II atom lies on a crystallographic twofold axis and is coordinated by four N atoms and two O atoms from two deprotonated tridentate 2-(2-pyridylmethyleneamino)benzenesulfonate ligands in a slightly distorted octahedral environment.There are extensive hydrogen bonds of the type O-HÁ Á ÁO between the uncoordinated water molecules and the sulfonate O atoms, through which the complex forms a layered structure parallel to (001).

Figure 2 2
Figure 2 2-D network, as viewed down the c axis.Dashed lines indicate hydrogen bonds.