2-Phenylimidazole−PdCl<sub>2</sub> and 2-Phenylimidazoline−PdCl<sub>2</sub> Complexes: Single-Crystal and Powder X-ray Diffractometry, <sup>1</sup>H 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-1<i>H</i>-imidazole)palladium(II) (<b>1</b>) and dichlorobis(2-phenyl-4,5-dihydro-1<i>H</i>-imidazole)palladium(II) (<b>2</b>) and <sup>1</sup>H NMR structure elucidation in DMF-<i>d</i><sub>7</sub> solution are discussed. In the case of complex <b>1</b>, we found that changing the solvent for recrystallization from a mixture of DMF and toluene (method A) to only DMF (method B) afforded complexes <b>2</b> and <b>2′</b>, having crystallographically different structures. <sup>1</sup>H NMR studies indicated that the spectra of the solid samples <b>2</b> and <b>2′</b> are the same in DMF-<i>d</i><sub>7</sub>. This indicated that the Pd−N bond rotates easily in solution, whereas complexes <b>2</b> and <b>2′</b> coexist through strong packing in the solid state. The catalytic activities of Pd complexes <b>1</b> and <b>2</b> in coupling reactions such as the Mizoroki−Heck reaction and Suzuki−Miyaura coupling will also be disclosed.