Hexakis(1H-imidazole-κN3)nickel(II) triaquatris(1H-imidazole-κN3)nickel(II) bis(naphthalene-1,4-dicarboxylate)

The crystal structure of the title compound, [Ni(C3H4N2)6][Ni(C3H4N2)3(H2O)3](C12H6O4)2, contains uncoordinated naphthalenedicarboxylate dianions and two kinds of NiII complex cations, both assuming distorted octahedral geometries. One NiII ion is located on an inversion center and is coordinated by six imidazole molecules, while the other NiII ion is located on a twofold rotation axis and is coordinated by three water molecules and three imidazole molecules in a mer-NiN3O3 arrangement. The naphthalenedicarboxylate dianion links both NiII complex cations via O—H...O and N—H...O hydrogen bonding, but no π–π stacking is observed between aromatic rings in the crystal structure. One imidazole ligand is equally disordered over two sites about a twofold rotation axis; one N atom and one water O atom have site symmetry 2