Role of electron-transfer processes in reactions of diarylcarbenium ions and related quinone methides with nucleophiles

Armin R. Ofial; Kei Ohkubo; Shunichi Fukuzumi; Roland Lucius; Herbert Mayr

doi:10.1021/ja035191v

Role of electron-transfer processes in reactions of diarylcarbenium ions and related quinone methides with nucleophiles

Armin R. Ofial, Kei Ohkubo, Shunichi Fukuzumi, Roland Lucius, Herbert Mayr

Department of Chemistry & Nanoscience

Research output: Contribution to journal › Article › peer-review

47 Scopus citations

Abstract

Second-harmonic alternating current voltammetry has been used to determine one-electron reduction potentials of 15 diarylcarbenium ions and 5 structurally analogous quinone methides, which have been employed as reference electrophiles for the development of nucleophilicity scales. A linear correlation (r ² = 0.993) between the empirical electrophilicity parameters E and the reduction potentials in acetonitrile (E = 14.091 E°_red - 0.279) covering a range of 1.64 V (or 158 kJ mol^-1) has been observed. For a large number of nucleophiles, it has been demonstrated that the observed activation free energies of the electrophile-nucleophile combinations are 61-195 kJ mol^-1 smaller than the free energy change of electron transfer from nucleophile to electrophile, which definitely excludes outer-sphere electron transfer occurring during these reactions.

Original language	English
Pages (from-to)	10906-10912
Number of pages	7
Journal	Journal of the American Chemical Society
Volume	125
Issue number	36
DOIs	https://doi.org/10.1021/ja035191v
State	Published - 10 Sep 2003

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title = "Role of electron-transfer processes in reactions of diarylcarbenium ions and related quinone methides with nucleophiles",

abstract = "Second-harmonic alternating current voltammetry has been used to determine one-electron reduction potentials of 15 diarylcarbenium ions and 5 structurally analogous quinone methides, which have been employed as reference electrophiles for the development of nucleophilicity scales. A linear correlation (r 2 = 0.993) between the empirical electrophilicity parameters E and the reduction potentials in acetonitrile (E = 14.091 E°red - 0.279) covering a range of 1.64 V (or 158 kJ mol-1) has been observed. For a large number of nucleophiles, it has been demonstrated that the observed activation free energies of the electrophile-nucleophile combinations are 61-195 kJ mol-1 smaller than the free energy change of electron transfer from nucleophile to electrophile, which definitely excludes outer-sphere electron transfer occurring during these reactions.",

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T1 - Role of electron-transfer processes in reactions of diarylcarbenium ions and related quinone methides with nucleophiles

AU - Ofial, Armin R.

AU - Ohkubo, Kei

AU - Fukuzumi, Shunichi

AU - Lucius, Roland

AU - Mayr, Herbert

PY - 2003/9/10

Y1 - 2003/9/10

N2 - Second-harmonic alternating current voltammetry has been used to determine one-electron reduction potentials of 15 diarylcarbenium ions and 5 structurally analogous quinone methides, which have been employed as reference electrophiles for the development of nucleophilicity scales. A linear correlation (r 2 = 0.993) between the empirical electrophilicity parameters E and the reduction potentials in acetonitrile (E = 14.091 E°red - 0.279) covering a range of 1.64 V (or 158 kJ mol-1) has been observed. For a large number of nucleophiles, it has been demonstrated that the observed activation free energies of the electrophile-nucleophile combinations are 61-195 kJ mol-1 smaller than the free energy change of electron transfer from nucleophile to electrophile, which definitely excludes outer-sphere electron transfer occurring during these reactions.

AB - Second-harmonic alternating current voltammetry has been used to determine one-electron reduction potentials of 15 diarylcarbenium ions and 5 structurally analogous quinone methides, which have been employed as reference electrophiles for the development of nucleophilicity scales. A linear correlation (r 2 = 0.993) between the empirical electrophilicity parameters E and the reduction potentials in acetonitrile (E = 14.091 E°red - 0.279) covering a range of 1.64 V (or 158 kJ mol-1) has been observed. For a large number of nucleophiles, it has been demonstrated that the observed activation free energies of the electrophile-nucleophile combinations are 61-195 kJ mol-1 smaller than the free energy change of electron transfer from nucleophile to electrophile, which definitely excludes outer-sphere electron transfer occurring during these reactions.

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Role of electron-transfer processes in reactions of diarylcarbenium ions and related quinone methides with nucleophiles

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