Palladium(II) and Platinum(II) Deprotonated Diaminocarbene Complexes Based on <i>N</i>-(2-Pyridyl)ureas with Oxadiazole Periphery

Abstract

Metal mediated coupling of isocyanides with substituted N-(pyridine-2-yl) ureas was first used to incorporate privileged biological motifs into platinum metal complexes. We synthesized two palladium(II) and two platinum(II) cyclometallated species with oxadiazole cores. The compounds were isolated in good yields (61–73%) and characterized by high-resolution mass spectrometry and 1H, 13C, and 195Pt NMR spectroscopies. The structures of three complexes were additionally elucidated by X-ray diffraction analysis. These complexes indeed showed cytotoxic activity. The species bearing the 1,3,4-oxadiazole moiety exhibit more potency than the ones with the 1,2,4-oxadiazole ring. Particularly, the cytotoxic effect of both 1,3,4-oxadiazole-based complexes towards T98G cells significantly exceeds the common antitumor metal-drug cisplatin.

Keywords

• cyclometallated platinum metal complexes
• <i>N</i>-(pyridine-2-yl) ureas
• metal mediated coupling
• isocyanides
• cytotoxic activity