Synthesis, structural characterization and catalytic activity of two N-heterocyclic carbene–phosphine palladium(II) complexes

Two new N-heterocyclic carbene (NHC)-phosphine palladium(II) complexes Pd(IMeo)PPh3I2 1 and Pd(IMeo) P(C6H4-p-Me)3I2 2 (IMeo = 1,3-di-4-methoxyphenyl- imidazolin-2-ylidene) have been easily prepared from the reaction of the corresponding iodide-bridged NHC dimer with phosphine ligands in high yields. Complexes 1 and 2 were characterized by elemental analysis, IR, 1H NMR, ESI-MS and single-crystal X-ray analysis. Complex 1 adopts a trans geometry in the solid state, while 2 is cis. The common features of the structures of these complexes are intermolecular Csingle bondH⋯I and Csingle bondH⋯O hydrogen bonds. These complexes were found to be efficient catalysts for the Suzuki reaction of aryl bromides.