Structural, fluorescent and theoretical studies of a more flexible salamo-type ligand and its uncommon tetranuclear chloride-bridged nickel(II) complex

•Synthesis of a uncommon chloride-bridged salamo-type Ni(II) complex.•The TD-DFT calculation verifies the type of ultraviolet electronic transition.•Quantitative analyzes of intermolecular interactions in the crystalline structures were performed by Hirshfeld analysis.•The reaction sites were predicted by IRI, ESP and other weak interaction force analysis. What is the shape of a more flexible salamo-type ligand? Unexpectedly single crystals of the ligand and a uncommon tetranuclear chloride-bridged complex with Ni(II) [Ni4(L)2(µ2Cl)2(µ3OMe)2(MeOH)2] were acquired. Single-crystal X-ray analyzes revealed the true structure of the ligand to be a twisted rectilinear shape, with a unique structure providing a diverse coordination environment for the metal ions. The involvement of halogens in the bridging is uncommon, and Single-crystal X-ray analysis of the complex showed that each deprotonated methoxy group bridges three Ni(II) metals, and then three Ni(II) metals are bridged by two chloride ions, each chloride ion bridges two Ni(II) metals. At this point the geometries of all four Ni(II) atoms adopt 6-coordinated octahedral configurations. It was demonstrated in UV–visible titration test that the metal-to-ligand ratios in solution and the structure of the complex obtained by single-crystal X-ray analysis are consistent. The properties were predicted analytically by DFT theory calculations and the UV–vis absorption spectra obtained by TD-DFT theory calculations in general coincide with the test results. The weak interactions in the complex were analyzed by cell freedom, Hirshfed surface analysis, ESP and IRI calculations. Finally, the fluorescence properties were explored in detail. [Display omitted]