Synthesis, structural characterization, and catalytic performance of Pd(II) complexes with fluorine- and methyl-substituted Schiff bases: Experimental and theoretical insights

• Published in: INORGANIC CHEMISTRY COMMUNICATIONS
• Main Authors: Nasaruddin, Nur Husnina; Ahmad, Shahrul Nizam; Tajuddin, Amalina Mohd; Indriyani, Nova Pratiwi; Sakti, Aditya Wibawa; Permana, Yessi; Rahman, Nor Mas Mira Abd; Yusof, Nor Saadah Mohd; Bahron, Hadariah
• Format: Article
• Language: English
• Published: ELSEVIER 2025
• Subjects: Chemistry
• Online Access: https://www-webofscience-com.uitm.idm.oclc.org/wos/woscc/full-record/WOS:001440604100001
• ISSN: 1387-7003; 1879-0259
• DOI: 10.1016/j.inoche.2025.114186

Two meta-substituted Schiff bases were synthesized and characterized using physicochemical and spectroscopic analysis. These Schiff bases were complexed with palladium(II) to form [Pd(AD1F)] and [Pd(AD1Me)], both characterized through single-crystal X-ray diffraction, elemental analysis, molar conductivity, FTIR, 1H NMR, and UV-Vis spectroscopy. Pd(AD1F) crystallized in a monoclinic system (P21/c space group), with the phenolic oxygen and azomethine nitrogen chelating Pd(II) to form a distorted square planar geometry. The formation of the Pd(II) complexes was observed through the shifting of nu(C = N) peak and delta(HC = N) in IR and 1H NMR spectra, respectively. Additionally, the shift of the n-pi*(C = N) band in UV-Vis spectra corroborated the involvement of azomethine nitrogen in the complexation. Pd(AD1Me) has been previously reported in our earlier work. DFT calculations revealed similar electronic transitions at 259 nm (pi -> pi*) and 333 nm (n -> pi*), dominated by specific HOMO to LUMO transitions for [Pd(AD1Me)] and [Pd(AD1F)] with minor effects from substituents. [Pd(AD1F)] demonstrated catalytic activity in copper-free Sonogashira coupling, achieving a TOF of 2.4 h- 1 and a TON of 7.1 at 120 degrees C. Its higher ionization potential and lower electron affinity, as determined by DFT, support its superior catalytic performance compared to [Pd(AD1Me)].