Diaquabis(2-iodobenzoato-κO)bis(nicotinamide-κN 1)copper(II)

In the title complex, [Cu(C7H4IO2)2(C6H6N2O)2(H2O)2], the CuII cation is located on an inversion center and is coordinated by two monodentate 2-iodobenzoate (IB) anions, two nicotinamide (NA) ligands and two water molecules in a distorted octahedral coordination geometry. The dihedral angle between the carboxylate group and the adjacent benzene ring is 32.12 (14)°, while the pyridine ring and the benzene ring are oriented at a dihedral angle of 82.02 (5)°. The coordinating water molecule links with the carboxylate group via an intramolecular O—H⋯O hydrogen bond. In the crystal, N—H⋯O, O—H⋯O and weak C—H⋯O hydrogen bonds link the molecules into a three-dimensional supramolecular network.

In the title complex, [Cu(C 7 H 4 IO 2 ) 2 (C 6 H 6 N 2 O) 2 (H 2 O) 2 ], the Cu II cation is located on an inversion center and is coordinated by two monodentate 2-iodobenzoate (IB) anions, two nicotinamide (NA) ligands and two water molecules in a distorted octahedral coordination geometry. The dihedral angle between the carboxylate group and the adjacent benzene ring is 32.12 (14) , while the pyridine ring and the benzene ring are oriented at a dihedral angle of 82.02 (5) . The coordinating water molecule links with the carboxylate group via an intramolecular O-HÁ Á ÁO hydrogen bond. In the crystal, N-HÁ Á ÁO, O-HÁ Á ÁO and weak C-HÁ Á ÁO hydrogen bonds link the molecules into a three-dimensional supramolecular network.
In the title mononuclear complex, Cu II cation is located on an inversion center and is coordinated by two 2-iodobenzoate (IB) anions, two nicotinamide (NA) ligands and two water molecules, all ligands coordinating in a monodentate manner ( Fig. 1) (Aydın et al., 2012), (Sertçelik et al., 2012b) have also been reported, where all the ligands coordinate to the metal atoms in a monodentate manner.
In the title complex, the four symmetry related O atoms (O1, O1′, O4 and O4′) in the equatorial plane around the Cu II ion form a slightly distorted square-planar arrangement, while the slightly distorted octahedral coordination is completed 2.5078 (16) Å (for water oxygens), and the Cu-N bond length is 1.9984 (16) Å, close to standard values (Allen et al., 1987). The Cu atom is displaced out of the mean-plane of the carboxylate group (O1/C1/O2) by -0.5995 (1) Å. The dihedral angle between the planar carboxylate group and the adjacent benzene ring A (C2-C7) is 32.12 (14)°. The benzene A (C2-C7) and the pyridine B (N1/C8-C12) rings are oriented at a dihedral angle of A/B = 82.02 (5)°. The coordinating water molecule links with the carboxylate group via an O-H···O hydrogen bond (Table 1).
In the crystal, intermolecular N-H···O, O-H···O and weak C-H···O hydrogen bonds (Table 1) link the molecules into a three-dimensional supramolecular network, in which they may be effective in the stabilization of the structure.

Experimental
The title compound was prepared by the reaction of CuSO 4 .5H 2 O (1.248 g, 5 mmol) in H 2 O (200 ml) and NA (1.220 g, 200 mmol) in H 2 O (20 ml) with 2-iodobenzoic acid (2.700 g, 10 mmol) in H 2 O (20 ml) at room temperature. The mixture was filtered and set aside to crystallize at ambient temperature for one week, giving blue single crystals.

Refinement
Atoms H21 and H22 (for NH 2 ) and H41 and H42 (for H 2 O) were located in a difference Fourier map and were refined freely. The C-bound H-atoms were positioned geometrically with C-H = 0.93 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 molecule with the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level [symmetry code: (′) -x, 1-y, -z].

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.