Nickel(II) Coordination Polymer Using Pyrazine Linkers and Phthalate Counter-Anion: Synthesis, Crystal Structure, Hirshfeld Surface and Voids Analysis

Herein, a new Ni(II) carboxylate polymer, [Ni(Pyr)·4H 2 O]Phth, is synthesized by the reaction of NiSO 4 ·7H 2 O with equimolar amounts of phthalic acid (PhthH 2 ) as the counter-anion and pyrazine (Pyr) as an ancillary ligand in aqueous media. The crystal structure of [Ni(Pyr)·4H 2 O]Phth is investigated by single crystal X-rays diffraction analysis, which inferred the ionic nature of the complex. In cation, the Ni-center is coordinated by two pyrazine rings and four water molecules to form an octahedral coordination geometry. The crystal structure exists as a one-dimensional polymeric structure. The crystal packing is stabilized by O–H⋯O and C–H⋯O bonding. The non-covalent interactions are investigated by Hirshfeld surface analysis. The enrichment ratio delivers the tendency of the interaction of the pair of chemical moieties, which are involved in the packing of crystals. Moreover, void analysis is executed to look at the packing efficiency, which helps in predicting the mechanical response of the compound.