Diaquabis(2-bromobenzoato-κO)bis(N,N-diethylnicotinamide-κN 1)manganese(II)

The title MnII complex, [Mn(C7H4BrO2)2(C10H14N2O)2(H2O)2], is centrosymmetric. The molecule contains two 2-bromobenzoate (BB) and two diethylnicotinamide (DENA) ligands and two water molecules, all ligands being monodentate. The four O atoms in the equatorial plane around the Mn atom form a slightly distorted square-planar arrangement, while the distorted octahedral coordination is completed by the two N atoms of the DENA ligands in the axial positions. The dihedral angle between the carboxyl group and the adjacent benzene ring is 79.95 (11)°, while the pyridine and benzene rings are oriented at a dihedral angle of 45.66 (6)°. In the crystal structure, intermolecular O—H⋯O hydrogen bonds link the molecules into infinite chains.

Diaquabis(2-bromobenzoato-κO)bis(N,N-diethylnicotinamide-κN 1 )manganese(II) Tuncer Hökelek, Hakan Dal, Barış Tercan, F. Elif Özbek and Hacali Necefoğlu S1. Comment Transition metal complexes with biochemically active ligands frequently show interesting physical and/or chemical properties, as a result they may find applications in biological systems (Antolini et al., 1982). The structural functions and coordination relationships of the arylcarboxylate ion in transition metal complexes of benzoic acid derivatives change depending on the nature and position of the substituent groups on the benzene ring, the nature of the additional ligand molecule or solvent, and the medium of the synthesis Shnulin et al., 1981). The nicotinic acid derivative N,N-diethylnicotinamide (DENA) is an important respiratory stimulant (Bigoli et al., 1972).
The structure determination of the title compound, (I), a manganese complex with two 2-bromobenzoate (BB), two diethylnicotinamide (DENA) 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 crystal structure, intermolecular O-H···O hydrogen bonds (Table 1)

S2. Experimental
The title compound was prepared by the reaction of MnSO 4 .H 2 O (0.85 g, 5 mmol) in H 2 O (20 ml) and DENA (1.78 g, 10 mmol) in H 2 O (20 ml) with sodium 2-bromobenzoate (2.23 g, 10 mmol) in H 2 O (50 ml). The mixture was filtered and set aside to crystallize at ambient temperature for 2 d, giving colorless single crystals.

S3. Refinement
H atoms of water molecule were located in difference Fourier maps and refined isotropically, with restrains of O4-H41 = 0.870 (15) Å and H41-O4-H42 = 106.6 (19)°. The remaining H atoms were positioned geometrically with C-H = 0.93, 0.97 and 0.96 Å, for aromatic, methylene 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 all other H atoms.

Special details
Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s 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 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.