Synthesis, structure, properties and theoretical studies of novel tetranuclear nickel(II) bis(salamo)-like complex

Abstract

Novel tetranuclear Ni(II) complex [Ni4(L)(acac)4(EtOH)2]⋅4CH2Cl2 was synthesized by a rigid bis(salamo)-like ligand H4L and Ni(acac)2 in ethanol/dichloromethane mixed solvents, and characterized by different physicochemical methods. The X-ray diffraction result showed that all Ni(II) atoms are hexa-coordinated with slightly distorted octahedral geometries, and four Ni(II) atoms are correlated with each other through inversion. Acetylacetone anions acted as auxiliary ligands for bidentate chelation, and the monodentate ethanol molecules of solvent participated in the coordination. The properties of the ligand H4L and its Ni(II) complex were studied, including molecular electrostatic potential surface (MEPs), Hirshfeld surface and interaction region indicator (IRI) analysis. Through the above study, the reaction active sites were visualized, and the intermolecular interactions of the Ni(II) complex were clarified, which is consistent with the crystal structure of the Ni(II) complex. In addition, fluorescence spectra of the ligand H4L and its Ni(II) complex were investigated.