A NOVEL TETRANUCLEAR NICKEL(II) SALAMO-BASED COMPLEX ADOPTING TWO OPEN CUBIC STRUCTURES: SYNTHESIS, CHRACTERIZATION, DFT CALCULATION, HIRSHFELD ANALYSIS, AND FLUORESCENT PROPERTIES.

A novel tetranuclear Ni(II) complex [Ni₄(L)₂(N₃)₄Cl(MeOH)₃]·CH₃COCH₃ is synthesized via a symmetrical salamo-based ligand H₂L, NiCl₂·6H₂O, and NaN₃. The structure is characterized by elemental analyses, IR and UV-Vis spectroscopy, and X-ray diffraction analysis. The X-ray crystal analysis shows that Ni(II) atoms in the Ni(II) complex have distorted octahedral geometries. It is the key factor that the ligand containing 3-position methoxy groups gives rise to the formation of the tetranuclear Ni(II) complex. When anions are used to bridge two Ni2 atoms, there are two symmetrical open cubic structures. The Ni(II) complex forms a 3D supramolecular structure through intermolecular hydrogen bond interactions. Using the Hirshfeld surface to clarify interactions between the molecules, the percentages of C–H/H–C, O–H/H–O, and H–H/H–H contacts are calculated as 19.0%, 15.3%, and 54.0%, respectively. Density functional theory (DFT) studies show that the stability of the Ni(II) complex is much higher than that of H₂L. The calculation of the fluorescence titration experiment can give K = 1.05·10⁸ M^–1, which further proves the stability of the Ni(II) complex. [ABSTRACT FROM AUTHOR]