Synthesis, characterization, DFT quantum chemical calculations and catalytic properties of azobenzene-bearing Schiff base palladium(II) complexes for the Suzuki-Miyaura Cross-Coupling reaction in aqueous solvent
Journal of Molecular Structure, cilt.1328, 2025 (SCI-Expanded, Scopus)
- Yayın Türü: Makale / Tam Makale
- Cilt numarası: 1328
- Basım Tarihi: 2025
- Doi Numarası: 10.1016/j.molstruc.2024.141296
- Dergi Adı: Journal of Molecular Structure
- Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Chemical Abstracts Core, Chimica, Compendex, INSPEC
- Anahtar Kelimeler: Azo-azomethine, Pd(II) complexes, Suzuki-miyaura coupling, C-C bond formation
- Sağlık Bilimleri Üniversitesi Adresli: Evet
Özet
A series of azobenzene-bearing Schiff base ligands, 4-((E)-(4-ethylphenyl)diazenyl)-2-((E)-(p-tolylimino)methyl)phenol (2), 4-((E)-(4-ethylphenyl)diazenyl)-2-((E)-((4-methoxyphenyl)imino)methyl)phenol (3), 2-((E)-((3,4-dimethoxyphenyl)imino)methyl)-4-((E)-(4-ethylphenyl)diazenyl)phenol (4), 2-((E)-((4-chlorophenyl)imino)methyl)-4-((E)-(4-ethylphenyl)diazenyl)phenol (5), 2-((E)-((4-bromophenyl)imino)methyl)-4-((E)-(4-ethylphenyl)diazenyl)phenol (6), 2-((E)-(tert‑butylimino)methyl)-4-((E)-(4-ethylphenyl)diazenyl)phenol (7), 2-((E)-(cyclohexylimino)methyl)-4-((E)-(4-ethylphenyl)diazenyl)phenol (8) and their homoleptic Pd(II) complexes have been synthesized. Ligand structures were characterized by the combination of 13CNMR, 1HNMR, FTIR, UV–Visible spectroscopy and elemental analyses. According to the UV–visible, FTIR, elemental analyses and HRMS data, the Pd(II) complexes 9–15 are formed by the coordination of N, O atoms of the ligands. Examining the coordination of the free ligands with the central metal ion, the new weak bands observed in the 633–581 and 543–481 cm−1 ranges in the spectra of the Pd(II) metal complexes can be attributed to M-O and M-N stretching peaks, respectively. DFT calculations were performed to determine the optimized structures of Pd(II) complexes utilizing the GAUSSIAN 16 software package with appropriate basis sets. The HOMO and LUMO energies of complexes 9–15 were calculated at the studied theory level in the gas phase. The ∆E values were found to be 3.136–3.239 eV range suggests the high chemical reactivity for those of Pd(II) complexes. In addition, Pd(II) complexes were used as catalysts for Suzuki-Miyaura coupling reactions of phenylboronic acid with aryl bromide in aqueous media. All complexes exhibited notably high catalytic properties in the Suzuki-Miyaura coupling reactions. It was found that the substitüe groups in the aryl bromide has an impact on the catalytic reaction. In the presence of an electron-withdrawing group such as 4-bromobenzaldehyde, the highest yields were obtained with catalysts 12 and 15, while the lowest yield was observed when catalyst 11 was used with 86 % efficiency.