Water Oxidation with Mononuclear Ruthenium(II) Polypyridine Complexes Involving a Direct RuIV鈺怬 Pathway in Neutral and Alkaline Media
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- 作者：Yosra M. Badiei ; Dmitry E. Polyansky ; James T. Muckerman ; David J. Szalda ; Rubabe Haberdar ; Ruifa Zong ; Randolph P. Thummel ; Etsuko Fujita
- 刊名：Inorganic Chemistry
- 出版年：2013
- 出版时间：August 5, 2013
- 年：2013
- 卷：52
- 期：15
- 页码：8845-8850
- 全文大小：373K
- 年卷期：v.52,no.15(August 5, 2013)
- ISSN：1520-510X
文摘
The catalytic water oxidation mechanism proposed for many single-site ruthenium complexes proceeds via the nucleophilic attack of a water molecule on the RuV鈺怬 species. In contrast, Ru(II) complexes containing 4-t-butyl-2,6-di-1鈥?8鈥?(naphthyrid-2鈥?yl)-pyridine (and its bisbenzo-derivative), an equatorial water, and two axial 4-picolines follow the thermodynamically more favorable 鈥渄irect pathway鈥?via [RuIV鈺怬]2+, which avoids the higher oxidation state [RuV鈺怬]3+ in neutral and basic media. Our experimental and theoretical results that focus on the pH-dependent onset catalytic potentials indicative of a PCET driven low-energy pathway for the formation of products with an O鈥揙 bond (such as [RuIII鈥揙OH]2+ and [RuIV鈥揙O]2+) at an applied potential below the RuV鈺怬/RuIV鈺怬 couple clearly support such a mechanism. However, in the cases of [Ru(tpy)(bpy)(OH2)]2+ and [Ru(tpy)(bpm)(OH2)]2+, the formation of the RuV鈺怬 species appears to be required before O鈥揙 bond formation. The complexes under discussion provide a unique functional model for water oxidation that proceeds by four consecutive PCET steps in neutral and alkaline media.