Diaquabis[4-(dimethylamino)benzoato-κO](isonicotinamide-κN 1)manganese(II)

The title MnII complex, [Mn(C9H10NO2)2(C6H6N2O)(H2O)2], contains two 4-(dimethylamino)benzoate (DMAB) anions, one isonicotinamide (INA) ligand and two coordinated water molecules. One of the DMAB anions acts as a bidentate ligand, while the other is monodentate. The four O atoms in the equatorial plane around the Mn atom form a highly distorted square-planar arrangement, while the distorted octahedral coordination geometry is completed by the N atom of the INA ligand and the O atom of the second water molecule in the axial positions. In the crystal structure, strong intermolecular O—H⋯O, O—H⋯N and N—H⋯O hydrogen bonds link the molecules into a two-dimensional network parallel to (010). Two weak C—H⋯π interactions are also found.

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 Mn 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, as in Zn II complexes (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 manganese 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 Mn atom is surrounded by two DMAB and INA ligands and two water molecules.  (Table 2) results in the formation of a six-membered ring D (Mn1/O1/O2/O6/C1/H61) adopting twisted conformation.
In the crystal structure, strong intermolecular O-H···O, O-H···N and N-H···O hydrogen bonds (Table 2) link the molecules into a two-dimensional network, in which they may be effective in the stabilization of the structure. Two weak C-H···π interactions ( and set aside to crystallize at ambient temperature for one week, giving colorless single crystals.

Refinement
H atoms of water molecules were located in difference Fourier maps and refined isotropically, with restrains of O6-H61    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.