Methoxido-Bridged Lacunary Heterocubane Oxidovanadium(IV) Cluster with Azo Ligands: Synthesis, X-ray Structure, Magnetic Properties, and Antiproliferative Activity

The new μ3-methoxido bridged trinuclear vanadium(IV) complexes [VIV3O3(μ3-OMe)(μ2-OMe)3(L1,2)2] (1 and 2) have been synthesized using the azo ligands 1-(2-(thiazol-2-yl)diazenyl)naphthalene-2-ol (HL1) and 2-(2-(thiazol-2-yl)diazenyl)-4-methylphenol (HL2). X-ray crystallography revealed a trinuclear structure with a lacunary heterocubane {(VO)3(μ3-OMe)(μ2-OMe)3}2+ core unit for complex 1, which contains a central μ3-methoxido bridge. All three vanadium centers are in a slightly distorted octahedral coordination environment. Magnetic and theoretical studies reveal an antiferromagnetic coupling between the three vanadium(IV) centers within the triangular arrangement in 1. The complexes were also screened for in vitro cytotoxicity study against HeLa and HT-29 cancer cell lines. The results indicated that both the complexes are cytotoxic but possess varying specificity towards different cell types.