Kineticomechanistic study of the redox pH cycling processes occurring on a robust water-soluble cyanido-bridged mixed-valence {CoIII/FeII}2 square
| Autor: | Manuel Martínez, Paul V. Bernhardt, Mercè Font-Bardia, Laura Alcázar, Albert Gallen, Timothy J. Zerk, Montserrat Ferrer, Jack S. Peters, Jesús Jover |
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| Přispěvatelé: | Universitat de Barcelona |
| Předmět: |
Valence (chemistry)
010405 organic chemistry Hydrogen bond Propietats magnètiques Protonation 010402 general chemistry Ligands 01 natural sciences Redox Complexos metàl·lics 0104 chemical sciences Ion Inorganic Chemistry chemistry.chemical_compound Crystallography Deprotonation Lligands Cyclen chemistry Metal complexes Magnetic properties Density functional theory Physical and Theoretical Chemistry |
| Zdroj: | Recercat. Dipósit de la Recerca de Catalunya instname Dipòsit Digital de la UB Universidad de Barcelona |
| Popis: | A kineticomechanistic study of reversible electron-transfer processes undergone by the water-soluble, cyanido-bridged mixed-valence [{CoIII{(Me)2(μ-ET)cyclen}}2{(μ-NC)2FeII(CN)4}2]2- square has been carried out. The oxidation reaction consists of a two-step process with the participation of a solvent-assisted outer-sphere complex, as a result of the establishment of hydrogen bonds that involve the oxo groups of the oxidant (peroxodisulfate) and the terminal cyanido ligands of the tetrametallic square. The formally endergonic reduction reaction of the fully oxidized ([{CoIII{(Me)2(μ-ET)cyclen}}2{(μ-NC)2FeIII(CN)4}2]) core by water, producing hydrogen peroxide from water even at low pH values, is also a two-step process. Each one of these processes requires a set of two preequilibria involving the association of OH- and its subsequent deprotonation by a further OH- anion. The structure of the square compound in its fully protonated form has also been determined by X-ray diffraction and shows the existence of strong hydrogen-bonding interactions, in agreement with the rather high basicity of the terminal cyanido ligands. Likewise, density functional theory calculations on the tetrametallic complex showed zones with negative electrostatic potential around the FeII centers of the square that would account for the establishment of the hydrogen bonds found in the solid state. Spectroelectrochemistry experiments demonstrated the singular stability of the {CoIII/FeII}2 2- complex, as well as that of their partially, {Co2 III/FeIIIFeII}-, and fully, {CoIII/FeIII}2, oxidized counterparts because no hysteresis was observed in these measurements.. |
| Databáze: | OpenAIRE |
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