Synthesis, crystal structure and Hirshfeld surface analysis of diaquabis(o-phenylenediamine-κ2N,N')-nickel(II) naphthalene-1,5-disulfonate

The reaction of o-phenylenediamine (OPD), sodium naphthalene1,5-di-sulfonate (Na2NDS) and nickel sulfate in an ethanol-water mixture yielded the title compound, [Ni(OPD)(2)(H2O)(2)]center dot 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 Ni-II atom is situated at a center of inversion and exhibits a slightly tetragonally distorted {O2N4} octahedral coordination environment, with four shorter equatorial Ni-N bonds [2.0775 (17) and 2.0924 (18) angstrom] and a longer axial Ni-O bond [2.1381 (17) angstrom]. The OPD ligand is located about an inversion center and is nearly coplanar with the NiN4 plane [dihedral angle 0.95 (9)degrees]. In the crystal, the cations and anions are connected by charge-assisted intermolecular N-H center dot center dot center dot O and O-H center dot center dot center dot O hydrogen-bonding interactions into the tri-periodic network structure. Hirshfeld surface analysis indicates that the most important contributions to the crystal packing are from H center dot center dot center dot H (44.1%), O center dot center dot center dot H/H center dot center dot center dot O (34.3%), C center dot center dot center dot H/H center dot center dot center dot C (14.8%) C center dot center dot center dot C (6.5%) (involving the cations) and O center dot center dot center dot H/H center dot center dot center dot O (50%), H...H (25%), C center dot center dot center dot H/H center dot center dot center dot C (15.3%), C center dot center dot center dot C (8.2%) (involving the anions) interactions.