Tetrakis(μ-2-iodobenzoato-κ2 O:O′)bis[aquacopper(II)]

In the centrosymmetric binuclear title complex, [Cu2(C7H4IO2)4(H2O)2], the two CuII ions [Cu⋯Cu = 2.6009 (5) Å] are bridged by four 2-iodobenzoate (IB) ligands. The four nearest O atoms around each CuII ion form a distorted square-planar arrangement, the distorted square-pyramidal coordination being completed by the O atom of the water molecule at a distance of 2.1525 (16) Å. The dihedral angle between the benzene ring and the carboxylate group is 25.67 (13)° in one of the independent IB ligands and 6.44 (11)° in the other. The benzene rings of the two independent IB ligands are oriented at a dihedral angle of 86.61 (7)°. In the crystal, O—H⋯O interactions link the molecules into a two-dimensional network. π–π contacts between the benzene rings [centroid–centroid distances = 3.810 (2) and 3.838 (2) Å] may further stabilize the structure.

In the centrosymmetric binuclear title complex, [Cu 2 (C 7 H 4 -IO 2 ) 4 (H 2 O) 2 ], the two Cu II ions [CuÁ Á ÁCu = 2.6009 (5) Å ] are bridged by four 2-iodobenzoate (IB) ligands. The four nearest O atoms around each Cu II ion form a distorted square-planar arrangement, the distorted square-pyramidal coordination being completed by the O atom of the water molecule at a distance of 2.1525 (16) Å . The dihedral angle between the benzene ring and the carboxylate group is 25.67 (13) in one of the independent IB ligands and 6.44 (11) in the other. The benzene rings of the two independent IB ligands are oriented at a dihedral angle of 86.61 (7) . In the crystal, O-HÁ Á ÁO interactions link the molecules into a two-dimensional network.contacts between the benzene rings [centroidcentroid distances = 3.810 (2) and 3.838 (2) Å ] may further stabilize the structure.

Experimental
The title compound was prepared by the reaction of CuSO 4 .5H 2 O (1.25 g, 5 mmol) in H 2 O (100 ml) with sodium 2-iodobenzoate (2.70 g, 10 mmol) in H 2 O (50 ml). The mixture was set aside to crystallize at ambient temperature for one day, giving green single crystals.

Refinement
Atoms H51 and H52 (for H 2 O) were located in a difference Fourier map and refined isotropically. 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 molecular structure of the title compound with the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level. Primed atoms are generated by the symmetry operator:(′) -x, -y, -z.

Tetrakis(µ-2-iodobenzoato-κ 2 O:O′)bis[aquacopper(II)]
Crystal data 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.