Synthesis, crystal structure and Hirshfeld surface analysis of di-aqua-bis-( o -phenyl-enedi-amine-κ 2 N , N ')nickel(II) naphthalene-1,5-di-sulfonate.

The reaction of o -phenyl-enedi-amine (OPD), sodium naphthalene1,5-di-sulfonate (Na 2 NDS) and nickel sulfate in an ethanol-water mixture yielded the title compound, [Ni(OPD) 2 (H 2 O) 2 ]·NDS or [Ni(C 6 H 8 N 2 ) 2 (H 2 O) 2 ](C 10 H 6 O 6 S 2 ). This salt consists of a complex [Ni(OPD) 2 (H 2 O) 2 ] 2+ cation with two bidentate OPD ligands and trans aqua ligands, and a non-coordinating NDS 2- anion, which is the double-deprotonated form of H 2 NDS. The Ni II atom is situated at a center of inversion and exhibits a slightly tetra-gonally distorted {O 2 N 4 } 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 NiN 4 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.