Tetra-aqua-(ethane-1,2-di-amine-κ,')nickel(II) naphthalene-1,5-di-sulfonate dihydrate.

The reaction of ethane-1,2-di-amine (en, CHN), the sodium salt of naphthalene-1,5-di-sulfonic acid (HNDS, CHOS), and nickel sulfate in an aqueous solution resulted in the formation of the title salt, Ni(CHN)(HO)·2HO or Ni(en)(HO)·2HO. In the asymmetric unit, one half of an [Ni(en)(HO)] cation and one half of an NDS anion, and one water mol-ecule of crystallization are present. The Ni cation in the complex is positioned on a twofold rotation axis and exhibits a slight tetra-gonal distortion of the -NiON octa-hedron, with an Ni-N bond length of 2.0782 (16) Å, and Ni-O bond lengths of 2.1170 (13) Å and 2.0648 (14) Å. The anion is completed by inversion symmetry. In the extended structure, the cations, anions, and non-coordinating water mol-ecules are connected by inter-molecular N-H⋯O and O-H⋯O hydrogen bonding, as well as C-H⋯π inter-actions, forming a three-dimensional network.