@article {ISI:000270186500047, title = {Influence of oxygenation on the reactivity of ruthenium-thiolato bonds in arene anticancer complexes: insights from XAS and DFT.}, journal = {J. Am. Chem. Soc.}, volume = {131}, number = {37}, year = {2009}, month = {sep}, pages = {13355{\textendash}61}, publisher = {American Chemical Society}, abstract = {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.}, keywords = {Antineoplastic Agents, Antineoplastic Agents: chemical synthesis, Antineoplastic Agents: chemistry, Antineoplastic Agents: metabolism, AROMATIC, Aromatic: chemistry, DFT, DNA, DNA: metabolism, Drug Design, ELECTRONS, HYDROCARBONS, LIGANDS, metal-based drugs, models, MOLECULAR, Molecular Conformation, ORGANOMETALLIC COMPOUNDS, Organometallic Compounds: chemical synthesis, Organometallic Compounds: chemistry, Organometallic Compounds: metabolism, OXYGEN, Oxygen: chemistry, quantum theory, ruthenium, Ruthenium: chemistry, Spectrum Analysis, Sulfhydryl Compounds, Sulfhydryl Compounds: chemistry, X-Rays, XAS}, issn = {1520-5126}, doi = {10.1021/ja903405z}, url = {http://www.ncbi.nlm.nih.gov/pubmed/19719101 http://dx.doi.org/10.1021/ja903405z}, author = {Sriskandakumar, Thamayanthy and Petzold, Holm and Bruijnincx, Pieter C A and Habtemariam, Abraha and Sadler, Peter J and Kennepohl, Pierre} } @article {ISI:000254173600010, title = {N-heterocyclic carbene complexes of Rh: reaction with dioxygen without oxidation.}, journal = {J. Am. Chem. Soc.}, volume = {130}, number = {12}, year = {2008}, month = {mar}, pages = {3724{\textendash}5}, abstract = {The reaction of oxygen with rhodium complexes containing N-heterocyclic carbenes was found to give dioxygen complexes with rare square planar geometries and unusually short O-O bond lengths. Analysis of the bonding in these complexes by Rh L-edge X-ray absorption spectroscopy (XAS), Raman spectroscopy, and DFT calculations provides evidence for a bonding model in which singlet oxygen is bound to a Rh(I) d8 metal complex, rather than the more common Rh(III) d6 peroxo species with octahedral geometry and O-O bond lengths in the 1.4-1.5 A range.}, keywords = {chemical, DFT, dioxygen complexes, Heterocyclic Compounds, Heterocyclic Compounds: chemistry, METHANE, Methane: analogs \& derivatives, Methane: chemistry, models, MOLECULAR, molecular structure, ORGANOMETALLIC COMPOUNDS, Organometallic Compounds: chemical synthesis, Organometallic Compounds: chemistry, OXYGEN, Oxygen: chemistry, rhodium, Rhodium: chemistry, SPECTROMETRY, X-Ray Emission, X-Ray Emission: methods, XAS}, issn = {1520-5126}, doi = {10.1021/ja7108213}, url = {http://www.ncbi.nlm.nih.gov/pubmed/18321109}, author = {Praetorius, Jeremy M and Allen, Daryl P and Wang, Ruiyao and Webb, Jonathan D and Grein, Friedrich and Kennepohl, Pierre and Crudden, Cathleen M} }