N-Heterocyclic Carbene Complexes RuII(Arene) and their Application as ROMP Catalysts, Antioxidant and Anticancer Agents

Abstract

N-Heterocyclic carbenes (NHCs) play an important role in metal complex catalysis and stabilisation, providing stability under non-inert conditions and a high σ-donor capacity. They are crucial ligands for the synthesis of organometallic compounds like Ru^II-complexes, which can operate as very active catalysts for a variety of chemical transformations and functionalizations. RA(Ruthenium-arene)NHC complexes, known for their piano-stool structure, stabilise Ru(II) oxidation state by occupying three ruthenium coordination sites with a η⁶-coordinated arene ligand. The development of dual-acting Ru^II-arene complexes has sparked increased interest in their catalytic and biological properties. Because of their broad spectrum, metal complexes can give distinct mechanisms of pharmacological action from organic drugs. This study aimed to explore the impact of ligand amphiphilicity and counterion on bioactivity, designing a family of compounds with the NHC ligand bearing an ester moiety and switching the wingtip substituent from methyl to benzyl units. All synthesized compounds were tested in norbornene ROMP, a benchmark reaction for Ru^II potential catalysts and as anticancer and antioxidant compounds.