Diaquabis[4-(dimethylamino)benzoato](isonicotinamide)zinc(II)

The molecule of the title ZnII complex, [Zn(C9H10NO2)2(C6H6N2O)(H2O)2], contains two 4-(dimethylamino)benzoate (DMAB) ligands, one isonicotinamide (INA) ligand and two water molecules; one of the DMAB ions acts as a bidentate ligand while the other and INA are monodentate ligands. The four O atoms in the equatorial plane around the Zn atom form a distorted square-planar arrangement, while the distorted octahedral coordination is completed by the N atom of the INA ligand and the O atom of the water molecule in the axial positions. Intramolecular C—H⋯O hydrogen bonding results in the formation of a six-membered ring adopting an envelope conformation. The dihedral angle between the carboxyl groups and the adjacent benzene rings are 4.87 (16) and 2.2 (2)°, while the two benzene rings are oriented at a dihedral angle of 65.13 (8)°. The dihedral angle between the benzene and pyridine rings are 11.47 (7) and 74.83 (8)°, respectively. In the crystal structure, intermolecular O—H⋯O, O—H⋯N and N—H⋯O hydrogen bonds link the molecules into a supramolecular structure. π–π contacts between the pyridine and benzene rings and between the benzene rings [centroid–centroid distances = 3.695 (1) and 3.841 (1) Å, respectively] further stabilize the structure. Weak intermolecular C—H⋯π interactions are also present.

The molecule of the title Zn II complex, [Zn(C 9 H 10 NO 2 ) 2 -(C 6 H 6 N 2 O)(H 2 O) 2 ], contains two 4-(dimethylamino)benzoate (DMAB) ligands, one isonicotinamide (INA) ligand and two water molecules; one of the DMAB ions acts as a bidentate ligand while the other and INA are monodentate ligands. The four O atoms in the equatorial plane around the Zn atom form a distorted square-planar arrangement, while the distorted octahedral coordination is completed by the N atom of the INA ligand and the O atom of the water molecule in the axial positions. Intramolecular C-HÁ Á ÁO hydrogen bonding results in the formation of a six-membered ring adopting an envelope conformation. The dihedral angle between the carboxyl groups and the adjacent benzene rings are 4.87 (16) and 2.2 (2) , while the two benzene rings are oriented at a dihedral angle of 65.13 (8) . The dihedral angle between the benzene and pyridine rings are 11.47 (7) and 74.83 (8) , respectively. In the crystal structure, intermolecular O-HÁ Á ÁO, O-HÁ Á ÁN and N-HÁ Á ÁO hydrogen bonds link the molecules into a supramolecular structure.contacts between the pyridine and benzene rings and between the benzene rings [centroidcentroid distances = 3.695 (1) and 3.841 (1) Å , respectively] further stabilize the structure. Weak intermolecular C-HÁ Á Á interactions are also present.

Diaquabis[4-(dimethylamino)benzoato](isonicotinamide)zinc(II)
T. Hökelek, H. Dal, B. Tercan, Ö. Aybirdi and H. Necefoglu Comment Nicotinamide (NA) is one form of niacin. A deficiency of this vitamin leads to loss of copper from the body, known as pellagra disease. Victims of pellagra show unusually high serum and urinary copper levels (Krishnamachari, 1974). The nicotinic acid derivative N,N-Diethylnicotinamide (DENA) is an important respiratory stimulant (Bigoli et al., 1972). Transition metal complexes with biochemical molecules show interesting physical and/or chemical properties, through which they may find applications in biological systems (Antolini et al., 1982). Some benzoic acid derivatives, such as 4-aminobenzoic acid, have been extensively reported in coordination chemistry, as bifunctional organic ligands, due to the varieties of their coordination modes (Chen & Chen, 2002;Amiraslanov et al., 1979;Hauptmann et al., 2000).
The structure-function-coordination relationships of the arylcarboxylate ion in Zn II complexes of benzoic acid derivatives may also change depending on the nature and position of the substituted groups on the benzene ring, the nature of the additional ligand molecule or solvent, and the pH and temperature of synthesis (Shnulin et al., 1981;Antsyshkina et al., 1980;Adiwidjaja et al., 1978). When pyridine and its derivatives are used instead of water molecules, the structure is completely different (Catterick et al., 1974).
The structure determination of the title compound, (I), a zinc complex with two 4-dimethylaminobenzoate (DMAB) and one isonicotinamide (INA) ligands and two water molecules, was undertaken in order to determine the properties of the ligands and also to compare the results obtained with those reported previously.
In the monomeric title complex, (I), the Zn atom is surrounded by two DMAB and INA ligands and two water molecules.
One of the DMAB ions acts as a bidentate ligand, while the other and INA are monodentate ligands (Fig. 1). The four O atoms (O1, O3, O4 and O7 atoms) in the equatorial plane around the Zn atom form a highly distorted square-planar arrangement, while the distorted octahedral coordination is completed by the N atom of the INA ligand (N1) and the O atom of the water molecule (O6) in the axial positions (Table 1 and (8), A/C = 11.47 (7) and B/C = 74.83 (8) °. Intramolecular C-H···O hydrogen bond (Table 2) results in the formation of a six-membered ring D (Zn1/O1/O2/O6/C1/ H61) adopting envelope conformation, with atom Zn1 displaced by 0.610 (1) Å from the plane of the other ring atoms. In (I), the O3-Zn1-O4 angle is 60.03 (6) Greenaway et al., 1984].

Experimental
The title compound was prepared by the reaction of   Fig. 1. The molecular structure of the title molecule with the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level. Hydrogen bond is shown as dashed line.

Diaquabis[4-(dimethylamino)benzoato](isonicotinamide)zinc(II)
Crystal data [Zn(C 9   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-supplementary materials sup-4 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.