After double deprotonation, 2,6-diaryl-p-benzoquinonodiimidazoles (aryl = 4-tolyl (I) or 2-pyridyl (II)) bridge two Ru(bpy)22+ (bpy = 2,2'-bipyridine) complex fragments through the imidazolate N and p-quinone O (I$\rightarrow$12+) or through the imidazolate N and pyridyl N donor atoms (II$\rightarrow$22+). Characterization by crystal structure anal., 1H/13C NMR spectroscopy, cyclic and differential pulse voltammetry, and spectroelectrochem. (UV/visible/NIR, IR, EPR) in combination with TD-DFT calcns. revealed surprisingly different electronic structures for redox systems 1n and 2n. Whereas 12+ is reduced to a radical complex with considerable semiquinone character, the redn. of 22+ with its exclusive N coordination exhibits little spin on the now redox-innocent quinone moiety, compared with the electron uptake by the pyridyl-imidazolate chelating site. The 1st of two close-lying oxidn. processes occurs at the bridging heteroquinone ligand, whereas the 2nd oxidn. is partly (14+) or predominantly (24+) centered on the metal atoms. on SciFinder(R)
%0 Journal Article
%1 Ansari.2018
%A Ansari, Mohd. Asif
%A Beyer, Katharina
%A Schwederski, Brigitte
%A Kaim, Wolfgang
%A Lahiri, Goutam Kumar.
%D 2018
%J Chemistry - An Asian Journal
%K ESR complex complex;ruthenium crystal diarylbenzoquinonodiimidazole potential prepn redox ruthenium structure
%N 19
%P 2947--2955
%R 10.1002/asia.201801101
%T Diruthenium Complexes of p-Benzoquinone-Imidazole Hybrid Ligands: Innocent or Noninnocent Behavior of the Quinone Moiety
%V 13
%X After double deprotonation, 2,6-diaryl-p-benzoquinonodiimidazoles (aryl = 4-tolyl (I) or 2-pyridyl (II)) bridge two Ru(bpy)22+ (bpy = 2,2'-bipyridine) complex fragments through the imidazolate N and p-quinone O (I$\rightarrow$12+) or through the imidazolate N and pyridyl N donor atoms (II$\rightarrow$22+). Characterization by crystal structure anal., 1H/13C NMR spectroscopy, cyclic and differential pulse voltammetry, and spectroelectrochem. (UV/visible/NIR, IR, EPR) in combination with TD-DFT calcns. revealed surprisingly different electronic structures for redox systems 1n and 2n. Whereas 12+ is reduced to a radical complex with considerable semiquinone character, the redn. of 22+ with its exclusive N coordination exhibits little spin on the now redox-innocent quinone moiety, compared with the electron uptake by the pyridyl-imidazolate chelating site. The 1st of two close-lying oxidn. processes occurs at the bridging heteroquinone ligand, whereas the 2nd oxidn. is partly (14+) or predominantly (24+) centered on the metal atoms. on SciFinder(R)
@article{Ansari.2018,
abstract = {After double deprotonation, 2,6-diaryl-p-benzoquinonodiimidazoles (aryl = 4-tolyl (I) or 2-pyridyl (II)) bridge two [Ru(bpy)2]2+ (bpy = 2,2'-bipyridine) complex fragments through the imidazolate N and p-quinone O (I$\rightarrow$12+) or through the imidazolate N and pyridyl N donor atoms (II$\rightarrow$22+). Characterization by crystal structure anal., 1H/13C NMR spectroscopy, cyclic and differential pulse voltammetry, and spectroelectrochem. (UV/visible/NIR, IR, EPR) in combination with TD-DFT calcns. revealed surprisingly different electronic structures for redox systems 1n and 2n. Whereas 12+ is reduced to a radical complex with considerable semiquinone character, the redn. of 22+ with its exclusive N coordination exhibits little spin on the now redox-innocent quinone moiety, compared with the electron uptake by the pyridyl-imidazolate chelating site. The 1st of two close-lying oxidn. processes occurs at the bridging heteroquinone ligand, whereas the 2nd oxidn. is partly (14+) or predominantly (24+) centered on the metal atoms. [on SciFinder(R)]},
added-at = {2022-06-15T11:26:56.000+0200},
author = {Ansari, Mohd. Asif and Beyer, Katharina and Schwederski, Brigitte and Kaim, Wolfgang and Lahiri, Goutam Kumar.},
biburl = {https://puma.ub.uni-stuttgart.de/bibtex/2ec7c905fa492ba1dcba10ef7ce5ba723/huebleriac},
doi = {10.1002/asia.201801101},
interhash = {066a4dd866264b073923bd222ed1fa72},
intrahash = {ec7c905fa492ba1dcba10ef7ce5ba723},
issn = {1861-4728},
journal = {Chemistry - An Asian Journal},
keywords = {ESR complex complex;ruthenium crystal diarylbenzoquinonodiimidazole potential prepn redox ruthenium structure},
number = 19,
pages = {2947--2955},
timestamp = {2022-06-15T09:26:56.000+0200},
title = {Diruthenium Complexes of p-Benzoquinone-Imidazole Hybrid Ligands: Innocent or Noninnocent Behavior of the Quinone Moiety},
volume = 13,
year = 2018
}
