Bis(μ-4-methyl­benzoato-κ(2) O:O′)bis­[aqua­(4-methyl­benzoato-κ(2) O,O′)zinc(II)]–bis­(μ-4-methyl­benzoato-κ(2) O:O′)bis­[(4-methyl­benzoato-κO)(nicotinamide-κN)zinc(II)]–water (1/1/2)

The crystal structure of the title compound, [Zn(2)(C(8)H(7)O(2))(4)(H(2)O)(2)]·[Zn(2)(C(8)H(7)O(2))(4)(C(6)H(6)N(2)O)(2)]·2H(2)O, consists of two kinds of dinuclear Zn(II) complexes (complex A and complex B) and uncoordinated water mol­ecules. In complex A, [Zn(2)(C(8)H(7)O(2))(4)(H(2)O)(2)], each Zn cation is chelated by a 4-methyl­benzoate (PMB) anion and coordinated by a water mol­ecule, and is further bridged by two PMB anions in a trigonal-bipyramidal geometry. In complex B, [Zn(2)(C(8)H(7)O(2))(4)(C(6)H(6)N(2)O)(2)], each Zn(II) cation is coordinated by a monodentate PMB anion and one nicotinamide (NA) ligand, and is further bridged by two PMB anions in a tetra­hedral geometry. Weak intra-mol­ecular π–π stacking between adjacent benzene rings is observed in complex B, the centroid–centroid distance being 3.710 (2) Å. Extensive O—H⋯O and N—H⋯O hydrogen bonding and weak C—H⋯O hydrogen bonding is present in the crystal structure. The crystal studied was a racemic twin; the minor twin component refined to 38%.