catena-Poly[[aqua(2-iodobenzoato-κO)cobalt(II)]-μ-aqua-μ-2-iodobenzoato-κ2 O:O′]

The asymmetric unit of the polymeric title compound, [Co(C7H4IO2)2(H2O)2]n, contains one CoII cation, two iodobenzoate anions and two water molecules. One iodobenzoate anion and one water molecule bridge adjacent Co cations, forming a polymeric chain running along the a axis, while the other iodobenzoate anion and water molecule coordinate in a monodentate manner to the CoII cation, completing the slightly distorted octahedral geometry. In the two independent anionic ligands, the carboxylate groups are twisted away from the attached benzene rings by 51.38 (18) and 39.89 (11)°, and the two benzene rings are nearly perpendicular to each other with a dihedral angle of 86.09 (10)°. Intramolecular O—H⋯O hydrogen bonds between coordinating water molecules and adjacent carboxylate O atoms help to stabilize the molecular structure. In the crystal, weak C—H⋯O hydrogen bonds link the polymeric chains into a three-dimentional supramolecular network.

The asymmetric unit of the polymeric title compound, [Co(C 7 H 4 IO 2 ) 2 (H 2 O) 2 ] n , contains one Co II cation, two iodobenzoate anions and two water molecules. One iodobenzoate anion and one water molecule bridge adjacent Co cations, forming a polymeric chain running along the a axis, while the other iodobenzoate anion and water molecule coordinate in a monodentate manner to the Co II cation, completing the slightly distorted octahedral geometry. In the two independent anionic ligands, the carboxylate groups are twisted away from the attached benzene rings by 51.38 (18) and 39.89 (11) , and the two benzene rings are nearly perpendicular to each other with a dihedral angle of 86.09 (10) . Intramolecular O-HÁ Á ÁO hydrogen bonds between coordinating water molecules and adjacent carboxylate O atoms help to stabilize the molecular structure. In the crystal, weak C-HÁ Á ÁO hydrogen bonds link the polymeric chains into a three-dimentional supramolecular network.
The asymmetric unit of the title compound, (I), contains one Co II ion, two 2-iodobenzoate (IB) ligands and two water molecules ( Fig. 1). In the crystal of the title compound, each Co II ion is coordinated by one IB ligand, one water molecule, two symmetry related IB ligands and two symmetry related water molecules, while the symmetry related Co(II) ions are bridged by the two O atoms of the symmetry related IB ligands and the two O atoms of the two symmetry related water molecules forming a polymeric chain. The coordination around the Co(II) ion is a slightly distorted octahedral (Fig. 2).
In the crystal, O-H···O and weak C-H···O hydrogen bonds (Table 2) link the molecules into a three-dimentional supramolecular network. A weak C-H···π interaction is also found in the crystal structure.

Experimental
The title compound was prepared by the reaction of CoSO 4 .7H 2 O (1.41 g, 5 mmol) in H 2 O (100 ml) with sodium 2-iodobenzoate (2.70 g, 10 mmol) in H 2 O (50 ml) at room temperature. The mixture was filtered and set aside to crystallize at ambient temperature for one week, giving orange single crystals.

Refinement
Atoms H51, H52, H61 and H62 (for H 2 O) were located in a difference Fourier map and were refined by applying restraints. The C-bound H-atoms were positioned geometrically with C-H = 0.95 Å for aromatic H-atoms, and constrained to ride on their parent atoms, with U iso (H) = 1.2 × U eq (C).

Figure 1
The asymmetric unit of the title molecule with the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level.  Part of the polymeric chain of the title compound.

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 > 2sigma(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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq I1