Kinetic Investigation of the Electrochemical Oxidation of Bis(benzene)chromium(0) in Diethyl ketone/N,N-Dimethylformamide
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The cyclic voltametric technique utilizing a platinum working electrode was applied for the investigation of the electrochemical oxidation of bis(benzene)chromium(0), (C6H6)2Cr to bis(benzene)chromium(I), (C6H6)2Cr+ in diethyl ketone (DEK), N,N-dimethylformamide (DMF), and DEK/DMF binary mixtures containing n-tetrabutylammonium hexafluorophosphate (TBAPF6) as the supporting electrolyte at T=298.15 K. The half-wave potentials (E 1/2) of the (C6H6)2Cr+/0 redox couple in DEK, DMF and DEK/DMF binary mixtures, were determined. The variation of E 1/2 with the solvent composition was found to be almost linear. The E 1/2 results were analyzed in terms of the electron-donating power of the solvent medium. The diffusion coefficients, D, were calculated using the Randles-Sevcik equation. The kinetics of the electrode reaction were investigated through the determination of the heterogeneous electron-transfer rate constants, k s, according to the electrochemical rate equation proposed by Nicholson. Furthermore, the activation Gibbs energies for the electron-transfer process (ΔG ≠) were also calculated. The results indicate that the redox couple (C6H6)2Cr+/0 exhibits an electrochemically reversible and diffusion-controlled process in all the investigated solvent media.
KeywordsActivation Gibbs energy Electron transfer Bis(benzene)chromium(0) Cyclic voltammetry Diethyl ketone Diffusion coefficient Electron transfer rate constant Half-wave potential N,N-Dimethylformamide
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