Imidazole-based phosphane gold(I) complexes as potential agents for cancer treatment: synthesis, structural studies and antitumour activity.

The reaction of the imidazolyl-4(5)-phosphane ligands 2-isopropylimidazol-4(5)yl-diphenylphosphane (4-MIP(iPr)) and tris(2-isopropylimidazol-4(5)yl)phosphane (4-TIP(iPr)) towards gold(I) has been explored and compared to those of analogous 1-methylimidazol-2-ylphosphane ligands. The structure of [(4-MIP(iPr))AuCl] () shows a linear P-Au-Cl coordination, whereas the 4-TIP(iPr) ligand forms a dinuclear complex [{(4-TIP(iPr))Au}(2)]Cl(2) (). Here, 4-TIP(iPr) bridges two gold(I) atoms in a head-to-tail P,N fashion. Complex forms in the presence of the hard Lewis acid ZnCl(2) the bimetallic complex [AuCl(4-TIP(iPr))ZnCl]Cl (), in which 4-TIP(iPr) bridges the two metal centers. In accordance with the HSAB concept the Au(I) atom is coordinated by the P atom and the zinc(II) by three N atoms in a N,N,N fashion. The solid-state structures of the complexes have been elucidated by single-crystal X-ray analysis. The Au(I)-Au(I) contact in is 2.8821(15) A. The biological activities of all imidazol-2-yl- and imidazol-4(5)-ylphosphane gold(I) complexes towards nine human cancer cell lines including seven ovarian cancer cell lines of different sensitivity towards cisplatin and two leukemia cell lines have been explored.