Bis(dimethylmalonato-κ2O,O′)bis[4-(4-pyridylamino-κN4)pyridinium]nickel(II) hexahydrate

In the title compound, [Ni(C5H6O4)2(C10H10N3)2]·6H2O, divalent nickel ions situated on the crystallographic twofold axis are octahedrally coordinated by four O atoms from two dimethylmalonate ligands in a 1,3-chelating mode and two N atoms from two protonated monodentate 4,4′-dipyridylamine molecules. The molecules link into chains via N—H...O hydrogen bonding mediated by protonated pyridyl groups. The chains form layer patterns via π–π stacking [centroid–centroid distance = 3.777 (2) ] . Water molecule hexamers are generated from the unligated water molecules (three per asymmetric unit) by inversion centers at Wyckoff position d. These clusters are situated between the pseudolayers, providing hydrogen-bonding pathways that build up the three-dimensional structure.