Diaqua­(5-carb­oxy­benzene-1,3-dicarboxyl­ato-κ(2) O (1),O (1′))(6,6′-dimethyl-2,2′-bipyridine-κ(2) N,N′)nickel(II) hepta­hydrate

In the title compound, [Ni(C(9)H(4)O(6))(C(12)H(12)N(2))(H(2)O)(2)]·7H(2)O, the Ni(II) atom is six-coordinated by two O atoms from a chelating carboxyl­ate group of a 5-carb­oxy­benzene-1,3-dicarboxyl­ate ligand, two O atoms of two water mol­ecules and two N atoms from a 6,6′-dimethyl-2,2′-bipyridine ligand in a distorted octa­hedral geometry. The compound exhibits a three-dimensional supra­molecular structure composed of the complex mol­ecules and lattice water mol­ecules, which are linked together by inter­molecular O—H⋯O hydrogen bonds and partly overlapping π–π inter­actions between the pyridine and benzene rings [centroid–centroid distances = 3.922 (2) and 3.921 (2) Å]. One of the lattice water mol­ecules is disordered over two positions in an occupancy ratio of 0.521 (6):0.479 (6).