Di-μ-nicotinamide-κ2 N 1:O;κ2 O:N 1-bis[aquabis(4-bromobenzoato)-κO;κ2 O,O′-manganese(II)]

In the centrosymmetric dinuclear title compound, [Mn2(C7H4BrO2)4(C6H6N2O)2(H2O)2], the MnII atom is coordinated by one N atom from one bridging nicotinamide ligand and one O atom from another symmetry-related bridging nicotinamide ligand, three O atoms from two 4-bromobenzoate ligands and one water molecule in a distorted octahedral geometry. The dihedral angles between the carboxylate groups and the adjacent benzene rings are 10.89 (16) and 8.4 (2)°, while the benzene rings are oriented at a dihedral angle of 6.09 (13)°. Intermolecular O—H⋯O, N—H⋯O and weak C—H⋯O hydrogen bonds link the molecules into a three-dimensional network. π–π interactions, indicated by short centroid–centroid distances [3.845 (2) Å between the benzene rings, 3.650 (2) Å between the pyridine rings and 3.700 (3) Å between the benzene and pyridine rings] further stabilize the structure.

In the centrosymmetric dinuclear title compound, [Mn 2 (C 7 H 4 BrO 2 ) 4 (C 6 H 6 N 2 O) 2 (H 2 O) 2 ], the Mn II atom is coordinated by one N atom from one bridging nicotinamide ligand and one O atom from another symmetry-related bridging nicotinamide ligand, three O atoms from two 4bromobenzoate ligands and one water molecule in a distorted octahedral geometry. The dihedral angles between the carboxylate groups and the adjacent benzene rings are 10.89 (16) and 8.4 (2) , while the benzene rings are oriented at a dihedral angle of 6.09 (13) . Intermolecular O-HÁ Á ÁO, N-HÁ Á ÁO and weak C-HÁ Á ÁO hydrogen bonds link the molecules into a three-dimensional network.interactions, indicated by short centroid-centroid distances [3.845 (2) Å between the benzene rings, 3.650 (2) Å between the pyridine rings and 3.700 (3) Å between the benzene and pyridine rings] further stabilize the structure.

Refinement
Atoms H6A, H6B (for H 2 O) and H2A, H2B (for NH 2 ) were located in a difference Fourier map and were freely refined.
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) = 1.2U eq (C). Fig. 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, -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.