Abstract
The asymmetric unit of the title compound, [Mn(C7H4NO4)2(C6H6N2O)2(H2O)2], contains one Mn(II) atom, one 4-nitro-benzoate (NB) anion, one nicotinamide (NA) ligand and one water mol-ecule; NA and NB each act as a monodentate ligand. The Mn(II) atom, lying on an inversion centre, is coordinated by four O atoms and two pyridine N atoms in a distorted octa-hedral geometry. The water mol-ecules are hydrogen bonded to the carboxyl-ate O atoms. The dihedral angle between the carboxyl-ate group and the adjacent benzene ring is 24.4 (3)°, while the benzene and pyridine rings are oriented at a dihedral angle of 86.63 (11)°. In the crystal, O-H⋯O and N-H⋯O hydrogen bonds link the mol-ecules, forming a layer parallel to the ab plane. The layers are further linked via weak C-H⋯O hydrogen bonds, a π-π stacking inter-action [centroid-centroid distance = 3.868 (2) Å] and a weak C-H⋯π inter-action, resulting in a three-dimensional network.