The Impact of Huge Structural Changes on Electron Transfer and Measurement of Redox Potentials: Reduction of ortho-12-Carborane
- Brookhaven National Lab. (BNL), Upton, NY (United States)
- Czech Academy of Sciences, Prague (Czech Republic)
- Univ. of Colorado, Boulder, CO (United States); Czech Academy of Sciences, Prague (Czech Republic)
A massive structural change accompanies electron capture by the 1,2-dicarba-closo-dodecaborane cage molecule (1). Bimolecular electron transfer (ET) by pulse radiolysis found a reduction potential of E0 = –1.92 V vs Fc+/0 for 1 and rate constants that slowed greatly for ET to or from 1 when the redox partner had a potential near this E0. Moreover, two electrochemical techniques could detect no current at potentials near E0, finding instead peaks or polarographic waves near –3.1 V, which is 1.2 V more negative than E0. Voltammetry could determine rate constants, but only near –3.1 V. DigiSim simulations can describe the irreversible voltammograms but require electrochemical rate constants near 1 × 10–10 cm/s at E0, a factor of 10–10 relative to molecules undergoing facile ET. This factor of 10–10 compared to ~10–5 for bimolecular ET introduces a puzzle. This puzzle can be understood as a manifestation of one of the “Frumkin Effects” in which only part of the applied voltage is available to drive ET at the electrode.
- Research Organization:
- Brookhaven National Laboratory (BNL), Upton, NY (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES)
- Grant/Contract Number:
- SC0012704
- OSTI ID:
- 1572367
- Report Number(s):
- BNL-212237-2019-JAAM; TRN: US2001322
- Journal Information:
- Journal of Physical Chemistry. B, Condensed Matter, Materials, Surfaces, Interfaces and Biophysical Chemistry, Vol. 123, Issue 45; ISSN 1520-6106
- Publisher:
- American Chemical SocietyCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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