Synthesis, characterization, and cytotoxicity studies of diimine derivatives and their ruthenium(II)-p-cymene complexes

The reaction of five di-imines obtained by condensation of etilendiamine with 4-hydroxybenzaldehyde (L¹), 2,4-dihydroxibenzaldehyde (L²) and 1-(2,4-dihydroxyphenyl)ethan-1-one (L³) or, condensations of glyoxal with 4-aminophenol (L⁴) and 4-amino-3-fluorphenol (L⁵) with [Ru₂(Cl)₄(η⁶-p-cymene)₂] was studied. In absence of silver salts, four cationic complexes of formula [RuCl(η⁶-p-cymene)(Lⁿ)]X where n = 1, 3, 4 and X = Cl and, n = 5 and X = PF₆ could be isolated as pure solid materials. The complexes were characterized by different spectroscopic techniques and the X-ray structures of the L¹ hydrate and its complex [RuCl(η⁶-p-cymene)(L¹)]Cl were also determined. These studies confirm the N,N’-bidentate nature of the ligand L¹ and the pseudo-octahedral geometry of the ruthenium coordination environment in the complex. Furthermore, the complex derived from L³, shows a potent cytotoxic activity against tumor cell line A549.