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The Decamethylferrocenium/Decamethylferrocene Redox Couple: A Superior Redox Standard to the Ferrocenium/Ferrocene Redox Couple for Studying Solvent Effects on the Thermodynamics of Electron Transfer

1999; American Chemical Society; Volume: 103; Issue: 32 Linguagem: Inglês

10.1021/jp991381+

1520-6106

Indra Noviandri, Kylie N. Brown, Douglas S. Fleming, Peter T. Gulyas, Peter A. Lay, Anthony F. Masters, Leonidas Phillips,

Electrochemical Analysis and Applications

The solvent dependence of the formal redox potentials of the ferrocenium/ferrocene (Fc+/0) and 1,2,3,4,5-pentamethylferrocenium/1,2,3,4,5-pentamethylferrocene (Me5Fc+/0) couples versus the decamethylferrocenium/decamethylferrocene (Me10Fc+/0) couple indicates that the latter is a superior redox standard for studying solvent effects on the thermodynamics of electron transfer. The couples were studied in 29 solvents and the differences in formal redox potentials between the MenFc+/0 (n = 5, 10) and Fc+/0 couples are surprisingly solvent dependent. In the case of the Fc+/0 couple versus the Me10Fc+/0 couple, the potential difference ranges from +583 mV in 2,2,2-trifluoroethanol to +293 mV in water. The positive shifts for the Me5Fc+/0 couple versus the Me10Fc+/0 couple were about half of these values. The Me10Fc+/0 redox couple can also be used in easily oxidized solvents, such as N-methylaniline and N,N-dimethylaniline, or in conjunction with a Hg working electrode. Statistical multiparameter analysis of th...