The interplay of coordination, π-π stacking and hydrogen bonding in the supramolecular self-assembly of bis(μ-7-iodo-8-hydroxyquinoline-5-sulfonato-κ3N,O:O′)bis[triaquanickel(II)] tetrahydrate

The title compound, [Ni(C9H4INO6S)(2)(H2O)(6)].4H2 O, is isomorphous with the corresponding cobalt(II) complex of ferron. Two inversion-related ligands and two Ni-II atoms form a cage-like dimer. Both ligands of the dimer are bridged by a pair of inversion-related Ni-O(sulfonate) bonds. The octahedral coordination geometry of nickel(II) is made up of the ring N atom, the deprotonated quinolinol O atom (the usual bidentate chelation), one of the sulfonate O atoms, and three water molecules. The ligands in the dimer are stacked over one another. This architecture is further stabilized by a number of O-H...O hydrogen bonds involving the deprotonated quinolinol O atom, sulfonate O atoms, and uncoordinated and coordinated water molecules.