Mononuclear ruthenium(II) complexes that catalyze water oxidation

Huan Wei Tseng, Ruifa Zong, James T. Muckerman, Randolph Thummel

Research output: Contribution to journalArticle

297 Citations (Scopus)

Abstract

Two series of mononuclear ruthenium(II) complexes involving polypyridine-type ligands have been prepared, and their ability to act as catalysts for water oxidation has been examined. One series is of the type [Ru(tpy)(NN)CI](PF6) (tpy = 2,2′; 6,2″-terpyridine), where NN is one of 12 different bidentate ligands, and the other series includes various combinations of 4-picoline, 2,2′-bipyridine (bpy), and tpy as well as the tetradentate 2,9-dipyrid-2′-yl-1,10-phenanthroline (dpp). The electronic absorption and redox data for these compounds have been measured and reported. The long-wavelength metal-to-ligand charge-transfer absorption and the first oxidation and reduction potentials are found to be consistent with the structure of the complex. Of the 23 complexes, 14 catalyze water oxidation and all of these contain a tpy or dpp. Kinetic measurements indicate a first-order reaction and together with a catalyst recovery experiment argue against the involvement of RuO2. A tentative mechanism is proposed that involves a seven-coordinate RuVI=O species that is attacked by water to form the critical O-O bond. Density functional theory calculations, which support the proposed mechanism, are performed.

Original languageEnglish
Pages (from-to)11763-11773
Number of pages11
JournalInorganic Chemistry
Volume47
Issue number24
DOIs
Publication statusPublished - Dec 1 2008

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Inorganic Chemistry

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