Cationic gold(i) heteroleptic complexes bearing a pyrazole-derived N-heterocyclic carbene: syntheses, characterizations, and cytotoxic activities

Abstract

A series of cationic gold(I) heteroleptic complexes bearing the pyrazole-derived N-heterocyclic carbene (NHC) FPyr (1,2,3,4,6,7,8,9-octahydropyridazino[1,2-a]indazolin-11-ylidene), and either a 1,3-disubstituted benzimidazole-derived NHC of the type RR′-bimy (3: R = R′ = CHPh₂; 4: R = CHPh₂, R′ = ⁱPr; 5: R = R′ = CH₂Ph; 6: R = R′ = ⁱBu; 7: R = R′ = n-Pr; 8: R = R′ = Et; 9: R = R′ = 2-propenyl) or a non-NHC co-ligand L (10: L = PPh₃; 11: L = P(OPh)₃; 12: L = DMAP) (DMAP = 4-dimethylaminopyridine) have been synthesized from [AuCl(FPyr)] (1). Complexes 3–12 have been characterized using multinuclei NMR spectroscopies, ESI mass spectrometry, and elemental analysis. X-ray diffraction analyses have been performed on complexes 5, 6, and 9–11. To the best of our knowledge, 11 represents the first gold–NHC complex to bear the P(OPh)₃ ligand. The cytotoxic activities of complexes 3–12 have been studied in vitro with the NCI-H1666 non-small cell lung cancer cell line.