Aquabis(isonicotinamide-κN 1)bis(4-methylbenzoato)-κO;κ2 O,O′-cadmium(II) monohydrate

In the crystal structure of the title compound, [Cd(C8H7O2)2(C6H6N2O)2(H2O)]·H2O, the CdII cation is coordinated by two 4-methylbenzoate (PMB) anions, two isonicotinamide (INA) ligands and one water molecule in a distorted octahedral CdN2O4 geometry. One of PMB ions acts as a bidentate ligand while the other and the two INA are monodentate ligands. An O—H⋯O hydrogen bond links the uncoordinated water molecule to the carboxyl groups of the complex. The dihedral angles between the carboxyl groups and the adjacent benzene rings are 10.28 (11) and 21.24 (9)°, while the two benzene rings and the two pyridine rings are oriented at dihedral angles of 6.90 (4) and 88.64 (4)°, respectively. In the crystal structure, O—H⋯O and N—H⋯O hydrogen bonds link the molecules into a supramolecular structure. A π–π contact between the benzene rings [centroid–centroid distance = 3.911 (1) Å] may further stabilize the crystal structure. Weak C—H⋯π interactions involving the pyridine rings also occur in the crystal structure.

In the crystal structure of the title compound, [Cd(C 8 H 7 O 2 ) 2 -(C 6 H 6 N 2 O) 2 (H 2 O)]ÁH 2 O, the Cd II cation is coordinated by two 4-methylbenzoate (PMB) anions, two isonicotinamide (INA) ligands and one water molecule in a distorted octahedral CdN 2 O 4 geometry. One of PMB ions acts as a bidentate ligand while the other and the two INA are monodentate ligands. An O-HÁ Á ÁO hydrogen bond links the uncoordinated water molecule to the carboxyl groups of the complex. The dihedral angles between the carboxyl groups and the adjacent benzene rings are 10.28 (11) and 21.24 (9) , while the two benzene rings and the two pyridine rings are oriented at dihedral angles of 6.90 (4) and 88.64 (4) , respectively. In the crystal structure, O-HÁ Á ÁO and N-HÁ Á ÁO hydrogen bonds link the molecules into a supramolecular structure. Acontact between the benzene rings [centroid-centroid distance = 3.911 (1) Å ] may further stabilize the crystal structure. Weak C-HÁ Á Á interactions involving the pyridine rings also occur in the crystal structure.

Comment
As a part of our ongoing investigation on transition metal complexes of nicotinamide (NA), one form of niacin (Krishnamachari, 1974), and/or the nicotinic acid derivative N,N-diethylnicotinamide (DENA), an important respiratory stimulant (Bigoli et al., 1972), the title compound was synthesized and its crystal structure is reported herein.  (Hökelek et al., 2009d) have also been reported.
In (II), the two benzoate ions are coordinated to the Cd atom as bidentate ligands. In the other structures one of the benzoate ligands acts as a bidentate ligand, while the other is monodentate ligand.
In the title compound ( Fig. 1), the average Cd-O bond length (Table 1)  In the crystal structure, intramolecular O-H···O and intermolecular O-H···O and N-H···O hydrogen bonds (Table 2) link the molecules into a supramolecular structure, in which they may be effective in the stabilization of the structure. The π-π contact between the benzene rings, Cg1-Cg2 i , [symmetry code (i): 1 + x, y, z, where Cg1 and Cg2 are the centroids of rings A (C2-C7) and B (C10-C15)] may further stabilize the structure, with centroid-centroid distance of 3.911 (1) Å.
There also exists two weak C-H···π interactions involving the pyridine rings C and D (Table 2).

Experimental
The title compound was prepared by the reaction of 3CdSO 4 .8H 2 O (1.29 g, 5 mmol) in H 2 O (40 ml) and INA (1.22 g, 10 mmol) in H 2 O (15 ml) with sodium 4-methylbenzoate (1.58 g, 10 mmol) in H 2 O (350 ml). The mixture was filtered and set aside to crystallize at ambient temperature for one week, giving colorless single crystals.
supplementary materials sup-2 Refinement Atoms H21, H22, H41, H42 (for NH 2 ) and H71, H72, H81, H82 (for H 2 O) were located in a difference Fourier map and refined isotropically. The remaining H atoms were positioned geometrically with C-H = 0.93 and 0.96 Å for aromatic and methyl H atoms and constrained to ride on their parent atoms, with U iso (H) = xU eq (C), where x = 1.5 for methyl H and x = 1.2 for aromatic H atoms. Fig. 1. The molecular structure of the title molecule with the atom-numbering scheme. Displacement ellipsoids are drawn at the 30% probability level. Dashed lines indicate the hydrogen-bondings.

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.