Synthesis, spectral characterization, and theoretical investigation of Ni(II) and Pd(II) complexes incorporating symmetrical tetradentate Schiff base ligand: Suzuki-Miyaura cross-coupling reaction using PdLSym

In the present work, a potential symmetric ONNO-tetradentate chelating ligand (H2LSym) has been utilized to prepare stable Ni(II) and Pd(II) complexes. The ligand was synthesized using 4,5-dimethyl-1,2-phenylenediamine and 3-ethoxysalicylaldehyde as precursors in the alcoholic media, while the complexes were prepared by using their corresponding acetate salts and ligand in a 1:1 molar ratio. The prepared compounds were then characterized by different analytical techniques like FT-IR, NMR, and CHN to detect their molecular structures. Furthermore, the electronic properties of the synthesized compounds were explored by using density functional theory (DFT). The molecular structures of the synthesized compounds were also optimized with the help of B3LYP method. The findings of the spectroscopic and theoretical data revealed that the ligand is coordinated via phenolic oxygen and imine nitrogen atoms. Finally, the catalytic potential of the palladium complex was explored for Suzuki-Miyaura cross-coupling reactions.