A Hirshfeld surface analysis, synthesis, structure and characterization of a new Ni(II) diamagnetic complex with the bidentate ligand homopiperazine

A new Ni(II) complex with the bidentate ligand homopiperazine, [Ni(C5H12N2)2](CH3COO)2.4H2O, has been prepared and characterized by single crystal X-ray diffraction, elemental analysis and IR spectroscopy. The basic coordination patterns of the homopiperazine coordinated metal cations are slightly distorted square planar. In the atomic arrangement, the cationic complexes [Ni(C5H12N2)2]2+ are interconnected by the CH3COO−anions via NH⋯O and CH⋯O hydrogen bonds to form layers parallel to the (a, b) plane. These layers are connected by hydrogen bonds generated with water molecules to build a three dimensional network. The charge density of the compound could be refined from X-ray diffraction data measured at cryogenic temperature. Intermolecular interactions were investigated by Hirshfeld surfaces. The title compound is diamagnetic as confirmed by theoretical calculations, allowing its 13C and 15N solid-state NMR spectra to be recorded. Absorption bands were identified by infrared spectroscopy. Electronic properties such as HOMO and LUMO energies were also obtained. [Display omitted] •A new coordination compound [Ni(C5H12N2)2](CH3COO)2.4H2O was synthesized.•The Ni(II) ion is in a slightly distorted square planar coordination geometry.•The crystal packing is stabilized by multiple hydrogen bonds.•Hirshfeld surface analysis was used to evaluate intermolecular contacts.