title: Proton-induced tuning of metal-metal communication in rack-type dinuclear Ru complexes containing benzimidazolyl moieties.
abstract: Ru complexes bearing a bis-tridentate benzimidazolyl ligand have been synthesized. The dinuclear ones act as a bibasic acid with pK(a1)=4.36 and pK(a2)=5.90. The protonated form of the dinuclear complex exhibited two one-electron oxidations at +0.91 and +1.02 V versus the ferrocenium/ferrocene (Fc/Fc(+)) couple (the potential difference (ΔE)=0.11 V), but the di-deprotonated form showed two waves at +0.50 and +0.58 V versus Fc/Fc(+) (ΔE=0.08 V). Since the potential difference between two waves reflects the strength of the metal-metal interaction, the deprotonation of the benzimidazole moieties in the complexes weakened the Ru-Ru communication. The degree of electronic coupling between two metal centers, estimated from the intervalence charge transfer (IVCT) band, was greater for the protonated form. DFT calculations for the protonated and deprotonated forms of the dinuclear complex suggest that the Ru(II)-L(H(2)) π* interaction plays a key role in the Ru-Ru interaction.
authors: Department of Applied Chemistry, Faculty of Science and Engineering, Chuo University, 1-13-27 Kasuga, Bunkyo-ku, Tokyo 112-8551, Japan.
authors: Katsuaki
authors: K
authors: Kobayashi
authors: Masamichi
authors: M
authors: Ishikubo
authors: Katsuhiko
authors: K
authors: Kanaizuka
authors: Keiko
authors: K
authors: Kosuge
authors: Shigeyuki
authors: S
authors: Masaoka
authors: Ken
authors: K
authors: Sakai
authors: Koichi
authors: K
authors: Nozaki
authors: Masa-aki
authors: MA
authors: Haga