Tuning of Redox Potentials by Introducing a Cyclometalated Bond to Bis-tridentate Ruthenium(II) Complexes Bearing Bis(N-methylbenzimidazolyl)benzene or -pyridine Ligands

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• 作者：Wen-Wen Yang ; Yu-Wu Zhong ; Shinpei Yoshikawa ; Jiang-Yang Shao ; Shigeyuki Masaoka ; Ken Sakai ; Jiannian Yao ; Masa-aki Haga
• 刊名：Inorganic Chemistry
• 出版年：2012
• 出版时间：January 16, 2012
• 年：2012
• 卷：51
• 期：2
• 页码：890-899
• 全文大小：550K
• 年卷期：v.51,no.2(January 16, 2012)
• ISSN：1520-510X

文摘

A series of asymmetrical bis-tridentate cyclometalated complexes including [Ru(Mebib)(Mebip)]⁺, [Ru(Mebip)(dpb)]⁺, [Ru(Mebip)(Medpb)]⁺, and [Ru(Mebib)(tpy)]⁺ and two bis-tridentate noncyclometalated complexes [Ru(Mebip)₂]²⁺ and [Ru(Mebip)(tpy)]²⁺ were prepared and characterized, where Mebib is bis(N-methylbenzimidazolyl)benzene, Mebip is bis(N-methylbenzimidazolyl)pyridine, dpb is 1,3-di-2-pyridylbenzene, Medpb is 4,6-dimethyl-1,3-di-2-pyridylbenzene, and tpy is 2,2鈥?6鈥?2鈥?terpyridine. The solid-state structure of [Ru(Mebip)(Medpb)]⁺ is studied by X-ray crystallographic analysis. The electrochemical and spectroscopic properties of these ruthenium complexes were studied and compared with those of known complexes [Ru(tpy)(dpb)]⁺ and [Ru(tpy)₂]²⁺. The change of the supporting ligands and coordination environment allows progressive modulation of the metal-associated redox potentials (Ru^II/III) from +0.26 to +1.32 V vs Ag/AgCl. The introduction of a ruthenium cyclometalated bond in these complexes results in a significant negative potential shift. The Ru^II/III potentials of these complexes were analyzed on the basis of Lever鈥檚 electrochemical parameters (E_L). Density functional theory (DFT) and time-dependent DFT calculations were carried out to elucidate the electronic structures and spectroscopic spectra of complexes with Mebib or Mebip ligands.