Holm Petzold

Influence of Oxygenation on the Reactivity of Ruthenium-Thiolato Bonds in Arene Anticancer Complexes: Insights from XAS and DFT

Thiolate ligand oxygenation is believed to activate cytotoxic half-sandwich [(eta(6)-arene)Ru(en)(SR)](+) complexes toward DNA binding. We have made detailed comparisons of the nature of the Ru-S bond in the parent thiolato complexes and mono- (sulfenato) and bis- (sulfinato) oxygenated species including the influence of substituents on the sulfur and arene. Sulfur K-edge XAS indicates that S(3p) donation into the Ru(4d) manifold depends strongly on the oxidation state of the sulfur atom, whereas Ru K-edge data suggest little change at the metal center. DFT results are in agreement with the experimental data and allow a more detailed analysis of the electronic contributions to the Ru-S bond. Overall, the total ligand charge donation to the metal center remains essentially unchanged upon ligand oxygenation, but the origin of the donation differs markedly. In sulfenato complexes, the terminal oxo group makes a large contribution to charge donation and even small electronic changes in the thiolato complexes are amplified upon ligand oxygenation, an observation which carries direct implications for the biological activity of this family of complexes. Details of Ru-S bonding in the mono-oxygenated complexes suggest that these should be most susceptible to ligand exchange, yet only if protonation of the terminal oxo group can occur. The potential consequences of these results for biological activation are discussed.

Metal and Ligand Control of Sulfenate Reactivity: Arene Ruthenium Thiolato‐Mono‐S‐Oxides

Going OS: Oxygenation of thiolate sulfur atoms can control biological signaling processes. Rare examples of a monodentate sulfenate ligands stabilized by hydrogen bonding to a diamine ligand within organometallic ruthenium arene complexes of pharmaceutical interest and their unusual acid/base properties are reported.

Oxidation induced by the antioxidant glutathione (GSH)

Remarkably efficient oxygen atom transfer from an intermediate of glutathione (GSH) autoxidation to an organometallic ruthenium arene thiolato complex is observed under physiologically-relevant conditions.

Selective Light Induced Cyclometalation in trans-(MesPh2P)2PtCl2

Reaction of mesityl diphenylphosphine (1) with PtCl2(cod) at room temperature afforded trans-PtCl2[(1)]2 (2). Using K2PtCl4 as starting material in refluxing mesitylene, the cyclometalated complex trans-PtCl[(1)(1– H)] (3) was isolated. Irradiation of complex 2 in dichloromethane with sunlight for 5 h provided a mixture of complexes 2 and 3 in a 1:4 ratio. The structures of 2 and 3 were established by X-ray crystallography.