Synthesis, characterization and catalytic activity in Suzuki-Miyaura coupling of palladacycle complexes with n-butyl-substituted N-heterocyclic carbene ligands

A series of monomeric palladacycle complexes bearing n-butyl-substituted N-heterocyclic carbenes, namely [Pd(NHC)X(dmba)] (dmba: dimethylbenzylamine and [Pd(NHC)X(ppy)]; NHC: 1-n-butyl-3-substituted benzylimidazol-2-ylidene; ppy: 2-phenylpyridine), were prepared either by transmetallation from the corresponding silver carbene complexes or by the reaction of the corresponding acetate-bridged palladacycle dimer with N-heterocyclic carbene ligands in high yields. The palladium(II) complexes were characterized using elemental analyses, APCI-MS, H-1 NMR and C-13 NMR spectroscopies. These complexes are efficient in the Suzuki-Miyaura coupling reaction between phenylboronic acid and aryl bromides.