Suzuki–Miyaura and Hiyama coupling catalyzed by PEPPSI-type complexes with non-bulky NHC ligand

• Synthesis and characterization of PEPPSI-type complexes bearing small NHC ligand.
• High catalytic activity of PEPPSI-type complexes in Suzuki and Hiyama reactions in ethylene glycol.
• Spectroscopic evidence of labile character of N-ligands coordinated to palladium.
• XPS and TEM identification of Pd(0) and Pd(0) NPs formed under reaction conditions.
• High and constant yield of non-symmetric biphenyl in ten subsequent runs.

Palladium PEPPSI-type complexes with small NHC ligand were applied as catalyst precursors in cross-coupling reactions forming a wide range of non-symmetric biaryls with high yields. The recycling of the in situ formed palladium composite was successfully performed in 10 subsequent runs. Mechanistic studies confirmed a labile character of the N-ligands coordinated to palladium by ligand exchange monitored using 1H NMR. The formation of Pd(0) NPs during the catalytic process was evidenced by TEM.

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