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

The reaction of ethane-1,2-di-amine (en, C(2)H(8)N(2)), the sodium salt of naphthalene-1,5-di-sulfonic acid (H(2)NDS, C(10)H(8)O(6)S(2)), and nickel sulfate in an aqueous solution resulted in the formation of the title salt, [Ni(C(2)H(8)N(2))(H(2)O)(4)](C(10)H(6)O(6)S(2))·2H(2)O or [Ni(en)(H(2)O)(4)](NDS)·2H(2)O. In the asymmetric unit, one half of an [Ni(en)(H(2)O)(4)](2+) cation and one half of an NDS(2-) anion, and one water mol-ecule of crystallization are present. The Ni(2+) cation in the complex is positioned on a twofold rotation axis and exhibits a slight tetra-gonal distortion of the cis-NiO(4)N(2) octa-hedron, with an Ni-N bond length of 2.0782†(16)†à , and Ni-O bond lengths of 2.1170†(13)†à and 2.0648†(14)†à . 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.