Bis(2-amino-6-methyl-pyridinium) trans-diaqua-bis-(pyrazine-2,3-dicarboxyl-ato)cuprate(II) hexa-hydrate.

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-dicarb-oxy-lic acid (pyzdcH(2)) and 2-amino-6-methyl-pyridine (2a-6mpy) in aqueous solution. The Cu(II) atom is located on an inversion centre and has an overall octa-hedral coordination environment. Two N and two O atoms from (pyzdc)(2-) ligands define the equatorial plane and two water mol-ecules are in axial positions, resulting in a typical tetra-gonally 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 inter-actions between aromatic rings of the cations [centroid-centroid distance = 3.58 (9) Å], lead to the formation of a three-dimensional supra-molecular structure.