A Ru(II) Bis-terpyridine-like Complex that Catalyzes Water Oxidation: The Influence of Steric Strain

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• 作者：Nattawut Kaveevivitchai ; Lars Kohler ; Ruifa Zong ; Maya El Ojaimi ; Nirja Mehta ; Randolph P. Thummel
• 刊名：Inorganic Chemistry
• 出版年：2013
• 出版时间：September 16, 2013
• 年：2013
• 卷：52
• 期：18
• 页码：10615-10622
• 全文大小：354K
• 年卷期：v.52,no.18(September 16, 2013)
• ISSN：1520-510X

文摘

The complexation of 2,9-dicarboxy-1,10-phenanthroline (DPA) with [Ru(tpy)Cl₃] (tpy = 2,2鈥?6,2鈥?terpyridine) provides a six-coordinate species in which one carboxyl group of DPA is not bound to the Ru(II) center. A more soluble tri-t-butyl tpy analogue is also prepared. Upon oxidation, neither species shows evidence for intramolecular trapping of a seven-coordinate intermediate. The role of the tpy ligand is revealed by the preparation of [Ru(tpy)(phenq)]²⁺ (phenq = 2-(quinol-8鈥?yl)-1,10-phenanthroline) that behaves as an active water oxidation catalyst (TON = 334). This activity is explained by the expanded coordination geometry of the phenq ligand that can form a six-membered chelate ring that better accommodates the linear arrangement of axial ligands required for optimal pentagonal bipyramid geometry. When a 1,8-naphthyidine ring is substituted for each of the two peripheral pyridine rings on tpy, increased crowding in the vicinity of the metal center impedes acquisition of the prerequisite reaction geometry.