Catalytic Water Oxidation by Mononuclear Ru Complexes with an Anionic Ancillary Ligand
2013 (English)In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 52, no 5, 2505-2518 p.Article in journal (Refereed) Published
Mononuclear Ru-based water oxidation catalysts containing anionic ancillary ligands have shown promising catalytic efficiency and intriguing properties. However, their insolubility in water restricts a detailed mechanism investigation. In order to overcome this disadvantage, complexes [Ru-II(bpc)(bpy)OH2](+) (1(+), bpc = 2,2'-bipyridine-6-carboxylate, bpy = 2,2'-bipyridine) and [Ru-II(bpc)(pic)(3)](+) (2(+), pic = 4-picoline) were prepared and fully characterized, which features an anionic tridentate ligand and has enough solubility for spectroscopic study in water. Using Ce-IV as an electron acceptor, both complexes are able to catalyze O-2-evolving reaction with an impressive rate constant. On the basis of the electrochemical and kinetic studies, a water nucleophilic attack pathway was proposed as the dominant catalytic cycle of the catalytic water oxidation by 1(+), within which several intermediates were detected by MS. Meanwhile, an auxiliary pathway that is related to the concentration of Ce-IV was also revealed. The effect of anionic ligand regarding catalytic water oxidation was discussed explicitly in comparison with previously reported mononuclear Ru catalysts carrying neutral tridentate ligands, for example, 2,2':6',2 ''-terpyridine (tpy). When 2(+) was oxidized to the trivalent state, one of its picoline ligands dissociated from the Ru center. The rate constant of picoline dissociation was evaluated from time-resolved UV-vis spectra.
Place, publisher, year, edition, pages
2013. Vol. 52, no 5, 2505-2518 p.
Dinuclear Ruthenium Complex, Molecular Catalysts, Spectral Properties, Redox Properties, Photosystem-Ii, Dimer Complex, Site, Mechanism, Evolution, IV
IdentifiersURN: urn:nbn:se:kth:diva-104805DOI: 10.1021/ic302446hISI: 000315763300034ScopusID: 2-s2.0-84874636594OAI: oai:DiVA.org:kth-104805DiVA: diva2:567443
FunderSwedish Research CouncilVinnovaKnut and Alice Wallenberg Foundation
QC 20130408. Updated from manuscript to article in journal.2012-11-132012-11-132013-04-08Bibliographically approved