Bis(2-amino-6-methyl­pyridinium) trans-diaqua­bis­(pyrazine-2,3-dicarboxyl­ato)cuprate(II) hexa­hydrate

The title compound, (C(6)H(9)N(2))(2)[Cu(C(6)H(2)N(2)O(4))(2)(H(2)O)(2)]·6H(2)O, was obtained by the reaction of CuCl(2)·2H(2)O with pyrazine-2,3-dicarb­oxy­lic acid (pyzdcH(2)) and 2-amino-6-methyl­pyridine (2a-6mpy) in aqueous solution. The Cu(II) atom is located on an inversion centre and has an overall octa­hedral coordination environment. Two N and two O atoms from (pyzdc)(2−) ligands define the equatorial plane and two water mol­ecules are in axial positions, resulting in a typical tetra­gonally Jahn–Teller-distorted environment. Extensive classical O—H⋯O, O—H⋯N and N—H⋯O and non-classical C—H⋯O hydrogen bonds, as well as π–π stacking inter­actions between aromatic rings of the cations [centroid–centroid distance = 3.58 (9) Å], lead to the formation of a three-dimensional supra­molecular structure.