Oxygen-Oxygen bond formation is the key step for the oxidation of water to molecular oxygen: a reaction of interest from a biological perspective and also for establishing new energy conversion schemes. A few Ru complexes have been described recently that are capable of catalyzing the water oxidation reaction, and their performance has been shown to be strongly dependent on, nuclearity, oxidation state and ligand topology.[1] A step forward in the field consists on unravelling the different reaction pathways trough which these reactions proceed. We have tackled this challenging topic by carrying out thorough electrochemical, spectroscopic and kinetic analysis together with O-18 labeling studies and DFT calculations. The combination of all these results gives evidence for mechanisms involving: intramolecular O-O bond formation, water nucleophilic attack and bimolecular O-O bond formation.[2]
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[1] (a) Sala, X.; Rodriguez, M.; Romero, I.; Escriche, L.; Llobet, A. Angew. Chem. Int. Ed. 2009, 48, 2842. (b) Romain, S.; Vigara, L.; Llobet, A. Acc. Chem. Res. 2009, 42, 1944-1953.
[2] (a) Sens, C.; Llobet, A. et al. J. J. Am. Chem. Soc. 2004, 126, 7798. (b) Mola, J.; Llobet, A. et al. Angew. Chem. Int. Ed. 2008, 47, 5830-5832. (c) Romain, S.; Bozoglian, F.; Sala, X.; Llobet, A., J. Am. Chem. Soc. 2009, 131, .2768. (d) Bozoglian, F.; Romain, S.; Ertem, Cramer, C. J.; Gagliardi, L.; Llobet, A. et al. J. Am. Chem. Soc. 2009, 15176-15187. (e) Sartorel, A.; Miró, P.; Llobet, A.; Bo, C.; Bonchio, M. et al. J. Am. Chem. Soc. 2009, 16051–16053. (f) Sala, X.; Ertem, M. Z.; Cramer, C. J.; Gagliardi, L.; Llobet, A. et al. Angew. Chem. Int. Ed. 2010, 49, 7745-7747. (g) Duan, L.; Bozoglian, F.; Mandal, S.; Stewart, B.; Privalov, T.; Llobet, A.; Sun, L., Nat. Chem. 2012, in press.