Tuning of redox potentials by introducing a cyclometalated bond to bis-tridentate ruthenium(II) complexes bearing bis(N -methylbenzimidazolyl) benzene or -pyridine ligands

Wen Wen Yang, Yu Wu Zhong, Shinpei Yoshikawa, Jiang Yang Shao, Shigeyuki Masaoka, Ken Sakai, Jiannian Yao, Masa Aki Haga

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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′:6′,2″-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's 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.

Original languageEnglish
Pages (from-to)890-899
Number of pages10
JournalInorganic chemistry
Issue number2
Publication statusPublished - Jan 16 2012


All Science Journal Classification (ASJC) codes

  • Physical and Theoretical Chemistry
  • Inorganic Chemistry

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