Redox-Active Organoruthenium(II)– and Organoosmium(II)–Copper(II) Complexes, with an Amidrazone–Morpholine Hybrid and [CuICl2]− as Counteranion and Their Antiproliferative Activity

Abstract

A novel proligand HLH has been prepared from 2-pyridinamidrazone and 6-(morpholinomethyl)pyridine-2-carboxaldehyde. Subsequently, starting from HLH and CuCl2·2H2O in the presence of triethylamine, a series of homo- and heterometallic complexes with [CuICl2]− as counteranion, namely mononuclear complex [CuIICl(HLOMe)][CuICl2] (1), dinuclear Ru(II)–Cu(II) complex [CuIIRuII(η6-p-cymene)Cl2(LH)][CuICl2]·1.5H2O (2·1.5H2O), Os(II)–Cu(II) complex [CuIIOsII(η6-p-cymene)Cl2(LH)][CuICl2]·H2O (3·H2O), and tetranuclear complex [CuII4(L1)2(L2)2Cl2]·5MeOH (4·5MeOH), where HLOMe, L1, and L2 are Schiff base ligands derived from HLH, were synthesized. The structures of metal complexes were established by X-ray diffraction. Complexes 1–3 demonstrated quasireversible one-electron reduction of Cu(II) in complex cations and one-electron oxidation of [CuICl2]− counterion, confirmed by UV–vis and EPR spectroelectrochemical measurements. They exhibited moderate antiproliferative activity against ovarian carcinoma and cervical ad...