INVESTIGATING THE STRUCTURAL AND SURFACE PROPERTIES OF COPPER AND NICKEL COMPLEXES FLUORINE-BASED SALEN TYPE SCHIFF BASES

Two new transition metal complexes, NiL1 (1) and CuL2 (2), with formulations C18H12F6N2NiO4 and C18H12CuF6N2O4, respectively, were synthesized through the slow evaporation method in ethanol. The synthesized complexes were extensively characterized using X-ray diffraction, Fourier transform infrared spectroscopy, and UV-Vis spectroscopy techniques. X-ray crystallographic analysis revealed that the Ni(II) and Cu(II) salen complexes consist of double deprotonated tetrafunctional chelating ligands, namely L1 for NiL1 and L2 for CuL2, along with the corresponding metal cations, Ni+2 and Cu+2. The asymmetric unit of NiL1 comprises half of the molecule, while the asymmetric unit of CuL2 consists of a single molecule. In the crystal lattice, the molecules of both complexes are interconnected through C–H···O and C–H···F hydrogen bonds. Additionally, weak π···π interactions contribute to the formation of a layered structure in both complexes. To gain further insight into the intermolecular interactions, Hirshfeld surface analysis was employed, enabling the identification of atom locations with potential for hydrogen bonding and providing a quantitative assessment of these interactions in the complexes. The analysis revealed that the dominant contributions to the Hirshfeld surface originated from F···H, H···H, and O···H contacts in both NiL1 and CuL2 complexes.