Differently structural Cu(II) and Ni(II) complexes of a nonsymmetrical tetradentate half-salamo like N3O-donor ligand: Synthesis, crystal structure, spectral properties and theoretical studies

•A quinoline-including half-salamo like N3O-donor ligand was synthesized.•Differently structural Cu(II) and Ni(II) complexes were synthesized and structurally characterized.•The intermolecular interactions were quantitatively analyzed by hirshfeld surfaces and 2D fingerprint plots. A half-salamo like N3O-donor ligand HL was synthesized and used for the construction of Cu(II) and Ni(II) complexes, namely as [Cu(L)(NO3)] (1) & [Ni2(L)2(NO3)2]·2H2O (2). The constructed complexes were structurally characterized by X‐ray crystallography technique. The results revealed that the complex 1 is the most common mononuclear species, in which Cu(II) ion is penta-coordinate with twisted square pyramid configuration. Unlike complex 1, the central Ni(II) ions of dinuclear complex 2 are hexa-coordinate possessing slightly distorted octahedron. The final supramolecular structures of the two complexes are stabilized and expanded by noncovalent interactions. In addition, spectral characteristics of the title complexes were examined. The frontier molecular orbitals as well as energy gaps of the complexes were explored by density functional theory calculation. The primary aspects of the ultraviolet absorption spectra were interpreted using time-dependent density functional theory computation. Thorough analysis of the Hirshfeld surfaces quantifies the interactions involved in the crystal structures of the Cu(II) and Ni(II) complexes. Two differently structural metal(II) complexes [Cu(L)(NO3)] (1) and [Ni2(L)2(NO3)2]·2H2O (2) containing a half-salamo like N3O-donor ligand were successfully synthesized and characterized. The spectral properties of the two complexes were studied. Moreover, the frontier molecular orbitals as well as energy gaps of the complexes were explored by DFT calculation. The Hirshfeld surfaces analyses and 2D fingerprint plots were performed to quantify the interactions involved in the crystal structures of the two complexes. [Display omitted]