A new CoII proton transfer compound based on pyrazine-2,3-dicarboxylic acid has been synthesized and structurally characterized. The title compound (2a- 6mpyH)2[Co(pyzdc)2(H2O)2]·8H2O, was obtained by the reaction of CoCl2·6H2O with pyrazine-2,3-dicarboxylic acid and 2-amino-6- methylpyridine in aqueous solution (molar ratio 1:2:2). The CoII ion is situated on an inversion centre and is coordinated by two O and two N atoms of two symmetry-related pyrazine-2,3-dicarboxylate ligands and two water molecules and has a disorted octahedral coordination environment. The asymmetric unit also contains four water molecules (Fig. 1). In the crystal structure, extensive intermolecular classical N−H···O, O−H···O and O−H···N hydrogen bonds and slipped or offset - stacking interactions [centroid-centroid distance = 3.490 (1) Å] connect the various components, forming a three-dimensional network. The water molecules in 1 can play an important role as gluing factor in the stabilization of supramolecular systems by creating divers H- bonds and resulted in the creation of six supramolecular synthons as R22(8), R34(10),R35(10), R4 5(15), R4 4(18), R4 4(26).

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