Synthesis, crystal structures, and catalytic activities of palladium imidazole complexes formed by 2-hydroxyethyl group cleavage

Abstract

N-4,6-dimethyl-2-pyrimidinylimidazole 1 and its hydroxyethyl derivative 1-(2-hydroxyethyl)-3-(4,6-dimethyl-2-pyrimidinyl)imidazolium chloride 2 have been synthesized and characterized. The attempted synthesis of bis(N-heterocyclic carbene)palladium complexes via the direct reaction of 2 with Pd(OAc)2 results in the unexpected formation of a bis(N-arylimidazole) palladium complex 3. Additionally, the analogous bis(N-methylimidazole) palladium complex 4 has also been synthesized by the above method. Compounds 1–4 were characterized by elemental analysis, IR, and 1H NMR. Additionally, their crystal structures have been determined by X-ray diffraction. Complexes 3 and 4 were found to be efficient catalysts for the Suzuki reaction.