2-Phenylimidazole−PdCl2 and 2-Phenylimidazoline−PdCl2 Complexes: Single-Crystal and Powder X-ray Diffractometry, 1H NMR Spectra, and Comparison of Catalytic Activities in Coupling Reactions

Single-crystal X-ray diffractometry and powder X-ray diffractometry of the complexes dichlorobis(2-phenyl-1H-imidazole)palladium(II) (1) and dichlorobis(2-phenyl-4,5-dihydro-1H-imidazole)palladium(II) (2) and 1H NMR structure elucidation in DMF-d7 solution are discussed. In the case of complex 1, we found that changing the solvent for recrystallization from a mixture of DMF and toluene (method A) to only DMF (method B) afforded complexes 2 and 2′, having crystallographically different structures. 1H NMR studies indicated that the spectra of the solid samples 2 and 2′ are the same in DMF-d7. This indicated that the Pd−N bond rotates easily in solution, whereas complexes 2 and 2′ coexist through strong packing in the solid state. The catalytic activities of Pd complexes 1 and 2 in coupling reactions such as the Mizoroki−Heck reaction and Suzuki−Miyaura coupling will also be disclosed.