Palladium(II) Complexes Bearing a Mixed Set of aNHC/Py/PR3/I2 Ligands: Applications in α-Arylation of Amide and Suzuki-Miyaura Coupling Reactions

ABSTRACT Complexes possessing abnormal or mesoionic carbene (aNHC or MIC) ligands are finding widespread applicability in organometallic chemistry owing to their various catalytic applications. Palladium(II) complexes bearing a mixed aNHC/Py/PR3/I2 (R = Ph, Cy) donor set are presented starting from a biphenyl derived triazolium salt. The complexes have been characterized by NMR spectroscopy and ESI mass spectrometry. Two complexes have also been structurally characterized by single crystal XRD. The PdII complexes have been tested as potent precatalysts for α-arylation of oxindole and Suzuki-Miyaura cross coupling reactions. Different donor ligands such as pyridine, 3-chloropyridine, 4-methoxypyridine, PPh3 and PCy3 have been used to compare the catalytic activities. The PdII complexes containing mixed aNHC/PR3/I2 donor set appeared to be more active catalysts when compared with the complexes bearing mixed aNHC/Py/I2 donor set in both catalytic transformations.