Hydrolysis and cytotoxic properties of osmium(II)/(III)-DMSO-azole complexes. Short communication.

The antiproliferative properties of the osmium(II) complexes cis,fac-[Os(II)Cl(2)(DMSO)(3)(L)] and trans,cis,cis-[Os(II)Cl(2)(DMSO)(2)(L)(2)] (L = 1H-pyrazole, 1H-imidazole) were studied in three human cancer cell lines, namely 41M (ovary), SK-BR-3 (breast), and SW480 (colon). Their activities were compared with those of osmium(III) and ruthenium(III) NAMI-A type complexes on HT-29 (colon) and SK-BR-3 cancer cell lines. While IC(50) values of all the Os(II) complexes were found to be >1000 microM in all cell lines, Os and Ru-NAMI-A type complexes showed remarkable antiproliferative activity.

Synthesis, structure, spectroscopic properties, and antiproliferative activity in vitro of novel osmium(III) complexes with azole heterocycles.

Reactions of (H 2azole) 2[OsCl 6], where Hazole = pyrazole, Hpz, ( 1), indazole, Hind, ( 2), imidazole, Him, ( 3) and benzimidazole, Hbzim, ( 4) with the corresponding azole heterocycle in 1:4 molar ratio in boiling isoamyl alcohol or hexanol-1 afforded novel water-soluble osmium(III) complexes of the type trans-[OsCl 2(Hazole) 4]Cl, where Hazole = Hpz ( 5a), Hind ( 6a), Him ( 7a), and Hbzim ( 9a) in 50-70% ( 5a, 7a, 9a) and 5% ( 6a) yields. The synthesis of 7a was accompanied by a concurrent reaction which led to minor formation (<4%) of cis-[OsCl 2(Him) 4]Cl ( 8). The complexes were characterized by elemental analysis, IR spectroscopy, UV-vis spectroscopy, ESI mass spectrometry, cyclic voltammetry, and X-ray crystallography.

Osmium NAMI-A analogues: synthesis, structural and spectroscopic characterization, and antiproliferative properties.

The osmium(III) complex [(DMSO)2H][trans-OsIIICl4(DMSO)2] (1) has been prepared via stepwise reduction of OsO4 in concentrated HCl using N2H(4).2HCl and SnCl(2).2H2O in DMSO.