Synthesis, spectral characterization, and X-ray crystal structure of Pd(II) complexes containing the orthometallated C,C-chelating ligand C₆H₄-PPh₂C(H)C(O)CH₂Cl

Abstract

The ylide-phosphonium salt [PPh₃CH₂C(O)CH₂Cl]⁺Cl⁻ (1) reacted with Pd(OAc)₂ to give the chloro-bridged dinuclear complex [Pd{C(H)PPh₃C(O)CH₂Cl}(μ-Cl)(OAc)]₂ (2), which underwent bridge cleavage reactions with a neutral bidentate N-donor to afford the cationic orthometallated complexes [Pd{(C,C)-C₆H₄PPh₂C(H)C(O)CH₂Cl}(N−N)]CF₃SO₃ [N−N=bipy (2,2’-bipyridine) (3), phen (1,10-phenanthroline) (4), 4-Me-phen (4-methyl-1,10-phenanthroline) (5), and 5-NO₂ phen (5-nitro-1,10-phenanthroline) (6)]. The complexes were identified and characterized by spectroscopic studies (IR and NMR). X-ray single-crystal analysis of 4 and 5 revealed the presence of an orthometallated C₆H₄-PPh₂ unit and a C-linked ylide Pd−C(H). Thermal behavior of 3–6 is investigated by thermogravimetry.

Keywords:

• CH-bond activation
• Cyclopalladated complex
• Phosphorus ylide
• Crystal structure

Acknowledgement

We are grateful for the financial support from the Department of Chemistry, Isfahan University of Technology (IUT).