Structure, dynamics and catalytic activity of palladium(II) complexes with imidazole ligands
作者:M.S. Szulmanowicz、W. Zawartka、A. Gniewek、A.M. Trzeciak
DOI:10.1016/j.ica.2010.08.037
日期:2010.12
Several palladium complexes of the type [Pd(im)(2)Cl-2], [Pd(im)(3)Cl]Cl, and [Pd(im)(4)]Cl-2 (im = imidazole 1,1-methylimidazole 2, 1,2-dimethylimidazole 3, 1-butylimidazole 4, 4a, 1-phenylimidazole 6, 1-phenylimidazoline 7, and 1-methylimidazoline 8) were prepared and structurally characterized. The square planar structure of two new complexes with the composition [Pd(im)(4)]Cl-2 (2b, 4b) was confirmed by X-ray analysis. In solution, exchange of imidazole ligands leading to heteroleptic products was evidenced by ESI-MS studies. Two bis-ligated complexes, bearing 1-methylimidazole (2a) and 1-propoxymethylimidazole (5) ligands, were obtained in the reaction of palladium with imidazoles formed by deprotection of one nitrogen atom in the respective imidazolium halides. Catalytic Suzuki-Miyaura reactions were carried out using the obtained palladium complexes in isopropanol-water solution. High yields of the cross-coupling products were obtained at 40 and 60 degrees C when 2-bromotoluene, 4-bromotoluene, and 4-bromoanizole were used as substrates. (C) 2010 Elsevier B.V. All rights reserved.