catena-Poly[[[[3-(2-pyridyl)-1H-pyrazole]cadmium(II)]-μ-oxalato] dihydrate]

In the title compound, {[Cd(C2O4)(C8H7N3)]·2H2O}n, the CdII ion is chelated by two O,O′-bidentate oxalate ions and an N,N′-bidentate 3-(2-pyridyl)-1H-pyrazole molecule, thereby generating a distorted cis-CdN2O4 octahedral geometry. Adjacent pairs of Cd ions are bridged by oxalate ions, resulting in wave-like polymeric chains propagating in [100]. The packing is consolidated by N—H—O and O—H—O hydrogen bonds.

As a continuation of these studies, we now report the crystal structure of the title complex.
As shown in figure 1, the Cd II ions are hexcoordianted, chelated by two oxalate and one 3-(2-pyridyl)pyrazole ligand (Table 1). While each oxalate ligand acts as one bridige to chalate two Cd ions, forming one wave-like line with Cd···Cd distance being 5.950 /%A, shown in Figure 2. The structure is consolidated by N-H···O and O-H···O hydrogen bonds (Table 2, Figure 3).
Upon cooling, colorless prisms of (I) were obtained from the reaction mixture.

S3. Refinement
All hydrogen atoms bound to carbon were refined using a riding model with C-H = 0.93 and U iso (H) = 1.2U eq (C). Two solvent water molecules are refined by using the ′DFIX′ command with the hydrogen atoms were separated with 1.38 Å, and the lengths of bond H-O were constrained with 0.82 Å with error 0.02Å and U iso = 1.5U eq (O).  A view of the title compound with the unique atom-labelling scheme. Displacement ellipsoids are drawn at the 30% probability level. Atoms labeled with A are at the symmetry position (-x,-y + 2,-z + 2).

Figure 2
A view of the chain strcuture of (I).  A view of the packing strcuture of (I).

catena-Poly[[[[3-(2-pyridyl)-1H-pyrazole]cadmium(II)]-µ-oxalato] dihydrate]
Crystal data Hall symbol: -P 1 a = 7.920 (2) Å b = 9.663 (2) Å c = 9.675 (2) Å α = 92.940 (4) where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max = 0.001 Δρ max = 0.38 e Å −3 Δρ min = −0.31 e Å −3 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.