Redox-Induced Hydrogen Bond Reorientation Mimicking Electronic Coupling in Mixed-Valent Diruthenium and Macrocyclic Tetraruthenium Complexes

We present the coordination-driven self-assembly of three tetranuclear metallacycles containing intracyclic NH2, OH, or OMe functionalities through the combination of various isophthalic acid building blocks with a divinylphenylene diruthenium complex. All new complexes of this study were characteri...

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Veröffentlicht in:Inorganic chemistry 2020-11, Vol.59 (22), p.16703-16715
Hauptverfasser: Fink, Daniel, Staiger, Anne, Orth, Nicole, Linseis, Michael, Ivanović-Burmazović, Ivana, Winter, Rainer F
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Sprache:eng
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Zusammenfassung:We present the coordination-driven self-assembly of three tetranuclear metallacycles containing intracyclic NH2, OH, or OMe functionalities through the combination of various isophthalic acid building blocks with a divinylphenylene diruthenium complex. All new complexes of this study were characterized by means of nuclear magnetic resonance spectroscopy, ultrahigh-resolution ESI mass spectrometry, cyclic and square wave voltammetry and, in two cases, X-ray diffraction. The hydroxy functionalized macrocycle 4-BOH and the corresponding half-cycle 2-OH stand out, as their intracyclic OH···O hydrogen bonds stabilize their mixed-valent one- (2-OH, 4-BOH) and three-electron-oxidized states (4-BOH). Despite sizable redox splittings between all one-electron waves, the mixed-valent monocations and trications do not exhibit any intervalence charge-transfer band, assignable to through-bond electronic coupling, but nevertheless display distinct IR band shifts of their charge-sensitive Ru­(CO) tags. We ascribe these seemingly contradicting observations to a redox-induced shuffling of the OH···O hydrogen bond(s) to the remaining, more electron-rich, reduced redox site.
ISSN:0020-1669
1520-510X
DOI:10.1021/acs.inorgchem.0c02695