Poly[[(2,2′-bipyridine)(μ3-2-sulfonatobenzoato)lead(II)] dihydrate]

In the title compound, {[Pb(sbc)(bpy)]·2H2O}n [bpy is 2,2′-bipyridine (C10H8N2) and sbc is the 2-sulfonatobenzoate dianion (C7H4O5S)], the PbII ion is bonded to four O atoms including carboxylate and sulfonate from three sbc dianions, and two N atoms from a chelating 2,2′-bipyridine ligand. The sbc ligand acts as a μ3-bridging ligand by one O atom of the sulfonate group and the two O atoms of the carboxylate. Of these two last O atoms, one builds up a dinuclear framework arranged around an inversion center whereas the second one links each dinuclear unit, forming a chain extending along the b axis. These polymeric chains are linked through O—H⋯O hydrogen bonds involving the water molecules, forming a layer parallel to (10).

In the title compound, {[Pb(sbc)(bpy)]Á2H 2 O} n [bpy is 2,2 0bipyridine (C 10 H 8 N 2 ) and sbc is the 2-sulfonatobenzoate dianion (C 7 H 4 O 5 S)], the Pb II ion is bonded to four O atoms including carboxylate and sulfonate from three sbc dianions, and two N atoms from a chelating 2,2 0 -bipyridine ligand. The sbc ligand acts as a 3 -bridging ligand by one O atom of the sulfonate group and the two O atoms of the carboxylate. Of these two last O atoms, one builds up a dinuclear framework arranged around an inversion center whereas the second one links each dinuclear unit, forming a chain extending along the b axis. These polymeric chains are linked through O-HÁ Á ÁO hydrogen bonds involving the water molecules, forming a layer parallel to (102).
The Pb atom might be regarded as six or seven coordinates if the second carboxylate O atom is considered as weakly bonding to the metal as observed in the related compound (C 34 H 20 N 2 O 8 Pb2)n (Yin & Yu, 2007) (Fig. 1). The Pb1-O2(symmetry code: ), 3.045 \%A, is much longer than the 2.745 \%A reported in the related complex, but it is still shorter than the sum of the Van der Waals radii. The geometry around the metal might be described as highly distorted monocaped octahedron.
The sbc ligand acts as a µ 3 -bridging ligands by one O atom of the sulfone group, and the two O atoms of the carboxylate.
Of these two last O atoms, one is building a dinuclear framework arranged around inversion center whereas the second one is linking each dinuclear unit to form a chain developping along the b axis. (Fig.2).
Interestingly, the water molecules are intercalated between the polymeric chains and link these chains through O-H ··· O hydrogen bonds to build up layers developping parallel to the (1 0 -2) plane (Table 1

Experimental
The title compound was synthesized by adding the DMF solution (10 ml) of 2,2'-bipyridine (0.03 g, 0.2 mmol) and 2,2'-dithiosalicylic acid (0.06 g, 0.2 mmol) dropwise to a stirred water solution (10 ml) of lead nitrate (0.07 g, 0.2 mmol) at 298 K temperature. Then the reaction mixture was filtered and the filtrate stood for about six weeks until the prism colorless crystals were obtained. The prism shaped crystals suitable for X-ray diffraction were collected by filtration, washed with water and ethanol and dried in air. The structure of (I) was determined by single crystal X-ray crystallography. Intensity data and unit-cell parameters for (I) were measured at 298 K on a Bruker Smart 1000 CCD diffractometer with graphite-monochromated Mo Kα radiation (λ=0.71073 Å) and a graphite monochromator using the ω-scan mode. All empirical absorption supplementary materials sup-2 corrections were applied by using the SADABS program [Bruker, 2002]. The structure was solved by direct methods and refined on F 2 by full-matrix leastsquares using the SHELXL-97 program package [Bruker, 2002].

Refinement
The water H atoms were refined subject to the restraint O-H = 0.82 (5) Å. The other H atoms were positioned geometrically and allowed to ride on their parent atoms at distances of 0.93 Å with U iso = 1.2U eq (parent atom).

Special details
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds 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 Rfactors(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.