Chemical and electrochemical oxidation of CpRe(PAr3)2H2 complexes to give stable 17-electron radical cations. Disproportionation to diamagnetic species via electron-transfer catalysis

1987 ◽  
Vol 109 (19) ◽  
pp. 5666-5673 ◽  
Author(s):  
Michael R. Detty ◽  
William D. Jones
Keyword(s):  
Electron Transfer ◽  
Electrochemical Oxidation ◽  
Radical Cations

Electrochemical oxidation of 6-propionyl-2-(N,N-dimethylamino)naphthalene (prodan) in acetonitrile on Pt electrodes: Reversible dimerization of prodan radical cations

2002 ◽  
Vol 80 (9) ◽  
pp. 1232-1241 ◽  
Author(s):  
Marcela Beatriz Moressi ◽  
María Alicia Zón ◽  
Héctor Fernández
Keyword(s):  
Electron Transfer ◽  
Cyclic Voltammetry ◽  
Diffusion Coefficient ◽  
Electrochemical Oxidation ◽  
Digital Simulation ◽  
Formation Rate ◽  
Radical Cations ◽  
Cyclic Voltammograms ◽  
Controlled Potential ◽  
Reversible Dimerization

The electrooxidation of 6-propionyl-2-(N,N-dimethylamino)naphthalene (prodan) has been investigated for the first time. It has been performed on both conventional size platinum electrodes and platinum ultramicroelectrodes in acetonitrile by cyclic voltammetry with convolution analysis and controlled-potential electrolysis. The voltammetric responses at room temperature are similar to those corresponding to a kinetically controlled anodic electron-transfer process. Cyclic voltammetry measurements were also carried out at different concentrations of prodan and at different temperatures. Chemical transformation of the radical monocation formed after the electrochemical oxidation of prodan, as deduced from reverse controlled potential bulk electrolysis and cyclic voltammetry measurements, gives evidence for the reversible dimerization of prodan radical cations. Both diagnostic criteria and digital simulation confirm that radical–radical coupling is the reversible chemical reaction coupled to the initial electron transfer step, to give the corresponding dimeric dication. The kinetic and thermodynamic parameters for the first electron transfer reaction and the dimerization process were estimated from digital simulation at 293 K. Values of 8.0 × 106 M–1 and 3.2 × 105 M–1 s–1 were determined for the dimerization reaction equilibrium constant and the dimer formation rate constant, respectively. The diffusion coefficient of prodan was determined from both limiting currents from convoluted cyclic voltammograms as well as limiting currents on ultramicroelectrodes. For such cases where the electron number exchanged in the electrode process is unknown, a method derived from the combination of data previously indicated is also proposed to obtain the diffusion coefficient of the electroactive species.Key words: prodan, cyclic voltammetry, reaction mechanism, reversible dimerization, electron transfer reactions, radical cation.

scholarly journals Spectral Probe for Electron Transfer and Addition Reactions of Azide Radicals with Substituted Quinoxalin-2-Ones in Aqueous Solutions

2021 ◽  
Vol 22 (2) ◽  
pp. 633
Author(s):  
Konrad Skotnicki ◽  
Slawomir Ostrowski ◽  
Jan Cz. Dobrowolski ◽  
Julio R. De la Fuente ◽  
Alvaro Cañete ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Aqueous Solutions ◽  
Absorption Spectra ◽  
Density Functional ◽  
Reduction Potential ◽  
Biological Significance ◽  
Radical Cations ◽  
Basis Sets ◽  
Double Bonds ◽  
Reduction Potentials

The azide radical (N3●) is one of the most important one-electron oxidants used extensively in radiation chemistry studies involving molecules of biological significance. Generally, it was assumed that N3● reacts in aqueous solutions only by electron transfer. However, there were several reports indicating the possibility of N3● addition in aqueous solutions to organic compounds containing double bonds. The main purpose of this study was to find an experimental approach that allows a clear assignment of the nature of obtained products either to its one-electron oxidation or its addition products. Radiolysis of water provides a convenient source of one-electron oxidizing radicals characterized by a very broad range of reduction potentials. Two inorganic radicals (SO4●−, CO3●−) and Tl2+ ions with the reduction potentials higher, and one radical (SCN)2●− with the reduction potential slightly lower than the reduction potential of N3● were selected as dominant electron-acceptors. Transient absorption spectra formed in their reactions with a series of quinoxalin-2-one derivatives were confronted with absorption spectra formed from reactions of N3● with the same series of compounds. Cases, in which the absorption spectra formed in reactions involving N3● differ from the absorption spectra formed in the reactions involving other one-electron oxidants, strongly indicate that N3● is involved in the other reaction channel such as addition to double bonds. Moreover, it was shown that high-rate constants of reactions of N3● with quinoxalin-2-ones do not ultimately prove that they are electron transfer reactions. The optimized structures of the radical cations (7-R-3-MeQ)●+, radicals (7-R-3-MeQ)● and N3● adducts at the C2 carbon atom in pyrazine moiety and their absorption spectra are reasonably well reproduced by density functional theory quantum mechanics calculations employing the ωB97XD functional combined with the Dunning’s aug-cc-pVTZ correlation-consistent polarized basis sets augmented with diffuse functions.

Surface photochemistry: Semiconductor mediated reactions of some 1,2-diarylcyclopropanes

1987 ◽  
Vol 65 (5) ◽  
pp. 976-979 ◽  
Author(s):  
Philip A. Carson ◽  
Paul de Mayo
Keyword(s):  
Electron Transfer ◽  
Radical Cations ◽  
Transfer Mechanism ◽  
Electron Transfer Mechanism ◽  
Trans Isomerization

1,2-Diphenylcyclopropane (1) was found to be oxidized on illuminated ZnO in the presence of air while 1-(p-methoxyphenyl)-2-phenylcyclopropane (2) and 1,2-bis(p-methoxyphenyl)cyclopropane (3) were found to be similarly oxidized on illuminated CdS. Compounds 2 and 3 were found, also, to undergo a rapid photochemical cis-trans isomerization on CdS whereas 1 did not undergo such isomerization. An electron transfer mechanism involving formation of the radical cations of the substrates is proposed.

scholarly journals Electron self-exchange activation parameters of diethyl sulfide and tetrahydrothiophene

2013 ◽  
Vol 9 ◽  
pp. 1448-1454
Author(s):  
Martin Goez ◽  
Martin Vogtherr
Keyword(s):  
Electron Transfer ◽  
Photoinduced Electron Transfer ◽  
Nuclear Polarization ◽  
Activation Barrier ◽  
Activation Parameters ◽  
Radical Cations ◽  
Free Energies ◽  
Time Resolved ◽  
Diethyl Sulfide ◽  
Chemically Induced

Electron transfer between the title compounds and their radical cations, which were generated by photoinduced electron transfer from the sulfides to excited 2,4,6-triphenylpyrylium cations, was investigated by time-resolved measurements of chemically induced dynamic nuclear polarization (CIDNP) in acetonitrile. The strongly negative activation entropies provide evidence for an associative–dissociative electron exchange involving dimeric radical cations. Despite this mechanistic complication, the free energies of activation were found to be well reproduced by the Marcus theory of electron transfer, with the activation barrier still dominated by solvent reorganization.

ChemInform Abstract: ELECTRON TRANSFER BETWEEN TETRAALKYLHYDRAZINE RADICAL CATIONS AND TETRAALKYLHYDRAZINES

1975 ◽  
Vol 6 (44) ◽  
pp. no-no
Author(s):  
S. F. NELSEN ◽  
P. J. HINTZ ◽  
J. M. BUSCHEK ◽  
G. R. WEISMAN
Keyword(s):  
Electron Transfer ◽  
Radical Cations
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