Synthesis and characterization of some transition metal complexes with pyridinium ylide and application of its palladium (II) complex in Suzuki-Miyaura coupling reaction

Pyridinium ylides are able to form stable complexes and could be characterized by spectroscopic techniques. They can behave as ambidentate ligands because the carbanion located at the Cα of the ylide is able to donate electron density to a transition metal. This work reports the synthesis and catalytic properties of new palladium complex which prepared by reaction of new pyridinium ylides (Y) and PdCl2. The reaction of pyridine with 2-Bromo-4 -fluoro acetophenone in dry chloroform produces new pyridinium salt (S). The action of Na2CO3 on S compound leads to a new type of stable ylide. The reaction of Y with palladium (II) Chloride in dry methanol as a solvent led to the formation of C-coordinated dimeric complex [PdY2Cl2]. Characterization of the Pd(II) complex was Optimized by IR, 1H and 13C NMR spectroscopy confirmed coordination of the ylide to the metal through the carbon atom. Also this complex has been found to act as efficient catalysts for the Suzuki cross-coupling reaction. Various aryl bromides were coupled with aryl boronic acids in DMF, under air, in the presence of 0.2 mol% of the catalyst to afford corresponding cross-coupled products in good to excellent yields. [1-3]