TY - JOUR
T1 - Proton-induced tuning of metal-metal communication in rack-type dinuclear Ru complexes containing benzimidazolyl moieties
AU - Kobayashi, Katsuaki
AU - Ishikubo, Masamichi
AU - Kanaizuka, Katsuhiko
AU - Kosuge, Keiko
AU - Masaoka, Shigeyuki
AU - Sakai, Ken
AU - Nozaki, Koichi
AU - Haga, Masa Aki
PY - 2011/6/14
Y1 - 2011/6/14
N2 - Ru complexes bearing a bis-tridentate benzimidazolyl ligand have been synthesized. The dinuclear ones act as a bibasic acid with pKa1=4.36 and pKa2=5.90. The protonated form of the dinuclear complex exhibited two one-electron oxidations at +0.91 and +1.02V versus the ferrocenium/ ferrocene (Fc/Fc+) couple (the potential difference (ΔE)=0.11V), but the di-deprotonated form showed two waves at +0.50 and +0.58V versus Fc/Fc+ (ΔE=0.08V). 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 RuII-L(H2) π* interaction plays a key role in the Ru-Ru interaction.
AB - Ru complexes bearing a bis-tridentate benzimidazolyl ligand have been synthesized. The dinuclear ones act as a bibasic acid with pKa1=4.36 and pKa2=5.90. The protonated form of the dinuclear complex exhibited two one-electron oxidations at +0.91 and +1.02V versus the ferrocenium/ ferrocene (Fc/Fc+) couple (the potential difference (ΔE)=0.11V), but the di-deprotonated form showed two waves at +0.50 and +0.58V versus Fc/Fc+ (ΔE=0.08V). 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 RuII-L(H2) π* interaction plays a key role in the Ru-Ru interaction.
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U2 - 10.1002/chem.201100074
DO - 10.1002/chem.201100074
M3 - Article
C2 - 21590824
AN - SCOPUS:79958084957
VL - 17
SP - 6954
EP - 6963
JO - Chemistry - A European Journal
JF - Chemistry - A European Journal
SN - 0947-6539
IS - 25
ER -