Use of 1,2,4-triazolo[1,5-a]pyrimidines to design new “piano-stool” ruthenium(II) compounds

A series of neutral half-sandwich organometallic ruthenium(II) complexes of the general formula [(η6-p-cym)Ru(L)Cl2], where η6-p-cym – p-cymene, was prepared by the direct reaction of a dichloride p-cymene ruthenium(II) dimer, [{(η6-p-cym)Ru(μ-Cl)}2Cl2], with corresponding 1,2,4-triazolo[1,5-a]pyrimidine ligands (L), namely, L-1,2,4-triazolo[1,5-a]pyrimidine (tp) (1), 5,7-dimethyl-1,2,4-triazolo[1,5-a]pyrimidine (dmtp) (2), 5,7-ditertbutyl-1,2,4-triazolo[1,5-a]pyrimidine (dbtp) (3), 7-isobutyl-5-methyl-1,2,4-triazolo[1,5-a]pyrimidine (ibmtp) (4), and 5,7-diphenyl-1,2,4-triazolo[1,5-a]pyrimidine (dptp) (5). The complexes were prepared in molar ratios of 1:2 (except (1), for which an excess of tp was used). The structures of the complexes were determined by multinuclear magnetic resonance (1H, 13C, 15N) spectroscopy and X-ray diffraction. According to all the spectroscopic data, the molecules adopted the usual “piano-stool” geometry with a monodentate N3 triazolopyrimidine ligand. Studies on these lipophilic ruthenium(II) complexes revealed rather low in vitro antiproliferative activities against two human cell lines.

Neutral half-sandwich organometallic ruthenium(II) complexes of the general formula [(η6-p-cym)Ru(L)Cl2], where η6-p-cym – p-cymene, was prepared by the direct reaction of a dichloride p-cymene ruthenium(II) dimer, [{(η6-p-cym)Ru(μ-Cl)}2Cl2], with corresponding 1,2,4-triazolo[1,5-a]pyrimidine ligands (L), namely, L-1,2,4-triazolo[1,5-a]pyrimidine (tp) (1), 5,7-dimethyl-1,2,4-triazolo[1,5-a]pyrimidine (dmtp) (2), 5,7-ditertbutyl-1,2,4-triazolo[1,5-a]pyrimidine (dbtp) (3), 7-isobutyl-5-methyl-1,2,4-triazolo[1,5-a]pyrimidine (ibmtp) (4), and 5,7-diphenyl-1,2,4-triazolo[1,5-a]pyrimidine (dptp) (5). The complexes were prepared in molar ratios of 1:2 (except (1), for which an excess of tp was used). The structures of the complexes were determined by multinuclear magnetic resonance (1H, 13C, 15N) spectroscopy and X-ray diffraction. According to all the spectroscopic data, the molecules adopted the usual “piano-stool” geometry with a monodentate N3 triazolopyrimidine ligand. Studies on these lipophilic ruthenium(II) complexes revealed rather low in vitro antiproliferative activities against two human cell lines.Figure optionsDownload as PowerPoint slide