Transition metal complexes with ligands of biochemical inter­est such as imidazole and some N-protected amino acids show inter­esting physical and/or chemical properties, through which they may find applications in biological systems (Antolini et al., 1982 ▸). The crystal structures of metal complexes with benzoic acid derivatives have been reported extensively because of the varieties of the coordination modes, for example, Co and Cd complexes with 4-amino­benzoic acid (Chen & Chen, 2002 ▸). The structures of some mononuclear complexes obtained from the reactions of transition metal(II) ions with nicotinamide (NA) and some benzoic acid derivatives as ligands have been determined previously, e.g. [Zn(C7H5O3)2(C6H6N2O)2] [(II); Necefoğlu et al., 2002 ▸], [Mn(C7H4ClO2)2(C10H14N2O)2(H2O)2] [(III); Hökelek et al., 2008 ▸] and [Zn(C7H4BrO2)2(C6H6N2O)2(H2O)2] [(IV); Hökelek et al., 2009 ▸].