X-ray structure of palladium (II) complex and its catalytic activity on Suzuki-Miyaura reaction under mild conditions

Abstract

Palladium (II) complex with 4-tert-butylbenzoic hydrazide (TBBH)/triphenylphosphine (PPh3) ligands was successfully synthesized and characterized by X-ray, H-1-NMR, C-13-NMR, P-31-NMR, FT-IR, UV-Vis, elemental analysis and magnetic measurements. Palladium (II) complex possesses distorted square planar geometry bearing neutral ligands at trans positions and two chloride anions as counter ions. The homogenous catalytic activity of synthesized complex was investigated on Suzuki-Miyaura reaction between phenyboronic acid and selected aryl halides. The effect of solvent, temperature, base, reaction time and substrate type were investigated. From the results, water mixed solvents including methanol, ethanol, dimethyl formamide and dimethyl sulfoxide found to be the most suitable solvents rather than the pure ones. Potassium carbonate, as an inorganic base, found to be much more effective than organic base additives (triethylamine and trimethylamine). Increasing reaction temperature and time resulted to obtain higher product yields. The best biphenyl formation was observed in methanol/water (1:1) mixture with the conversion value of 98.5%, at 50 degrees C in 1-h reaction time.