Photochemical Reactivity of RuII(η6-p-cymene) Flavonolato Compounds

Photoactivation is a promising approach for modulating the biological activity of RuII compounds. In this work, RuII flavonolato compounds, [Ru(η6-p-cymene)(L)(3-Hfl)]OTf (8; 3-Hfl = monoanion of 3-hydroxyflavone; L = solvent) and [Ru(η6-p-cymene)Cl(3-Hfl-X)] (3a–3c; 3-Hfl-X = p-H, -Cl, or -F on the flavonolato phenyl substituent), have been evaluated for photoinduced reactivity within the flavonolato unit upon irradiation with UV (300 nm) or visible (419 nm) light under aerobic conditions. For each compound, irradiation in CH3CN was found to result in the loss of the p-cymene ligand and the formation of products resulting from oxidative ring opening of the flavonolato ligand in a dioxygenase-type reaction. This reaction also results in the release of carbon monoxide. The RuII products generated in these reactions are [RuII(solvent)(carboxylato)]+ and [Ru(CO)(solvent)(carboxylato)]+ (carboxylato = O-benzoylsalicylato or benzoato) species, as determined by ESI-MS. The amount of free CO generated depends on...