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Two-electron transf...
Two-electron transfer for Tl(aq)(3+)/Tl(aq)(+) revisited. Common virtual Tl-II-Tl-III (4+) intermediate for homogeneous (superexchange) and electrode (sequential) mechanisms
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Khoshtariya, D. E. (författare)
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Dolidze, T. D. (författare)
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Zusman, L. D. (författare)
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- Lindbergh, Göran (författare)
- KTH,Kemiteknik
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- Glaser, Julius (författare)
- KTH,Kemi
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(creator_code:org_t)
- 2002-03-12
- 2002
- Engelska.
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Ingår i: Inorganic Chemistry. - : American Chemical Society (ACS). - 0020-1669 .- 1520-510X. ; 41:7, s. 1728-1738
- Relaterad länk:
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https://urn.kb.se/re...
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https://doi.org/10.1...
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Abstract
Ämnesord
Stäng
- Homogeneous and electrochemical two-electron transfers within the TI(aq)(3+)/TI(aq)(+) couple are considered on a common conceptual basis. For the 2 equiv electrochemical reduction of TI(aq)(3) to TI(aq)(+), the intermediate state with a formal reduction potential, E-1* = 1.04 +/- 0.10 V vs the normal hydrogen electrode, was detected, different from the established value of 0.33 V for a TI3+/TI2+ couple. Examination of obtained electrochemical (cyclic voltammetry (CV) and rotating disk electrode techniques, along with the CV-curve computer simulation procedure) and literature data indicate that the detected formal potential cannot be the property of electrode-adsorbed species, but rather of the covalently interacting dithallium intermediate [TI11-TI11](4+) located at the outer Helmholtz plane. The analysis of microscopic mechanisms, based on the recent hypothesis of H. Taube and the Marcus-Hush theory extended by Zusman and Beratan, and Koper and Schmickler, revealed that the homogeneous process most probably takes place through the superexchange inner-sphere two-electron-transfer mechanism, via an essentially virtual (undetectable) dithallium intermediate. In contrast, the electrochemical process occurs through a sequential mechanism, via the rate-determining step of TI(aq)(2+) ion formation immediately followed by activationless formation of the metastable (CV-active) dithallium state. The second electrochemical electron-transfer step is fast, and shows up only in the peak height (but not in the shape) of the observed CV cathodic wave, The anodic wave for a microscopically reverse process of the oxidation of TI(aq)(+) to TI(aq)(3+) cannot be observed within the considered potential range due to the blocking of through-space electron transfer by the competitor process of ion transfer to the electrode.
Nyckelord
- 2-electron transfer-reactions
- acidic aqueous-solution
- equilibrium dynamics
- thallium
- energy
- complexes
- platinum
- kinetics
- bromide
- system
Publikations- och innehållstyp
- ref (ämneskategori)
- art (ämneskategori)
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