Synthesis, crystal structure and Hirshfeld surface analysis of di-aqua-bis-(o-phenyl-enedi-amine-κ2N,N')nickel(II) naphthalene-1,5-di-sulfonate.

The reaction of o-phenyl-enedi-amine (OPD), sodium naphthalene1,5-di-sulfonate (Na2NDS) and nickel sulfate in an ethanol-water mixture yielded the title compound, [Ni(OPD)2(H2O)2]·NDS or [Ni(C6H8N2)2(H2O)2](C10H6O6S2). This salt consists of a complex [Ni(OPD)2(H2O)2]2+ cation with two bidentate OPD ligands and trans aqua ligands, and a non-coordinating NDS2- anion, which is the double-deprotonated form of H2NDS. The NiII atom is situated at a center of inversion and exhibits a slightly tetra-gonally distorted {O2N4} octa-hedral coordination environment, with four shorter equatorial Ni-N bonds [2.0775 (17) and 2.0924 (18) Å] and a longer axial Ni-O bond [2.1381 (17) Å]. The OPD ligand is located about an inversion center and is nearly coplanar with the NiN4 plane [dihedral angle 0.95 (9)°]. In the crystal, the cations and anions are connected by charge-assisted inter-molecular N-H⋯O and O-H⋯O hydrogen-bonding inter-actions into the tri-periodic network structure. Hirshfeld surface analysis indicates that the most important contributions to the crystal packing are from H⋯H (44.1%), O⋯H/H⋯O (34.3%), C⋯H/H⋯C (14.8%) C⋯C (6.5%) (involving the cations) and O⋯H/H⋯O (50%), H⋯H (25%), C⋯H/H⋯C (15.3%), C⋯C (8.2%) (involving the anions) inter-actions.

Tetra-aqua-(ethane-1,2-di-amine-κ2N,N')nickel(II) naphthalene-1,5-di-sulfonate dihydrate.

The reaction of ethane-1,2-di-amine (en, C2H8N2), the sodium salt of naphthalene-1,5-di-sulfonic acid (H2NDS, C10H8O6S2), and nickel sulfate in an aqueous solution resulted in the formation of the title salt, [Ni(C2H8N2)(H2O)4](C10H6O6S2)·2H2O or [Ni(en)(H2O)4](NDS)·2H2O. In the asymmetric unit, one half of an [Ni(en)(H2O)4]2+ cation and one half of an NDS2- anion, and one water mol-ecule of crystallization are present. The Ni2+ cation in the complex is positioned on a twofold rotation axis and exhibits a slight tetra-gonal distortion of the cis-NiO4N2 octa-hedron, with an Ni-N bond length of 2.0782 (16) Å, and Ni-O bond lengths of 2.1170 (13) Šand 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.