The crystal structure of a new polymorph of hexaaquanickel(II) bis(6-oxo-1,6-dihydropyridine-3-carboxylate)

In a new polymorph of the title salt, [Ni(H2O)(6)](C6H4NO3)(2), the metal atom of the cationic complex lies on a symmetry centre and is coordinated by six water molecules to provide a quite regular octahedral coordination environment. These cations interact with 6-oxo-1,6-dihydropyridine-3-carboxylate anions through electrostatic interactions and by means of O-H center dot center dot center dot O and N-H center dot center dot center dot O hydrogen bonds involving the carboxylate, keto and protonated imine groups of the anion, and the coordinating water molecules from the cationic complex entity to generate a supramolecular three-dimensional architecture. The previously reported polymorph of this compound presents a network of hydrogen bonds, in which the organic anions establish mutual hydrogen-bonding interactions involving their keto and protonated imine groups.