Substituenteneffekte und Störung von π-Systemen, XXXV Radikalanionen Zinn-substituierter Naphthaline/ Substituent Effects and Perturbation of n Systems, XXXV Radical Anions of Tin-Substituted Naphthalenes

1978 ◽  
Vol 33 (11) ◽  
pp. 1223-1226 ◽  
Author(s):  
Hans Bock ◽  
Wolfgang Kaim ◽  
Holger Tesmann
Keyword(s):  
Charge Transfer ◽  
Substituent Effects ◽  
Esr Spectra ◽  
Group Iv ◽  
Ionization Potentials ◽  
Radical Anions ◽  
Spin Distribution ◽  
Reduction Potentials ◽  
Half Wave ◽  
Wave Reduction

Abstract Novel radical anions of trimethylstannyl substituted naphthalenes and their ESR spectra are reported. Both 119 Sn and 117 Sn coupling can be assigned unequivocally. The perturbation of π systems by R3X substituents of group IV b elements X = C, Si, Ge, Sn and Pb is discussed with respect to photoelectron ionization potentials, charge transfer excitations, half-wave reduction potentials and ESR spin distribution.

Merostabilization in radical ions, triplets, and biradicals. 4. Substituent effects on the half-wave reduction potentials and n,π* triplet energies of aromatic ketones

1980 ◽  
Vol 58 (23) ◽  
pp. 2537-2549 ◽  
Author(s):  
William J. Leigh ◽  
Donald R. Arnold ◽  
Robert W. R. Humphreys ◽  
Po Cheong Wong
Keyword(s):  
Substituent Effects ◽  
Radical Ions ◽  
Normal Behaviour ◽  
Reduction Potentials ◽  
Half Wave ◽  
Substituent Constants ◽  
Parameter Function ◽  
Two Parameter ◽  
Wave Reduction ◽  
Abinitio Calculations

The half-wave reduction potentials, measured by cyclic voltammetry, and n,π* triplet energies, measured by phosphorescence spectroscopy, were determined for a series of eighteen symmetrically and unsymmetrically substituted benzophenones. Attempts are made to correlate the results with Hammett substituent constants. Better correlations are observed when the data are correlated with a two-parameter function consisting of Hammett substituent constants and a set of substituent parameters describing variations in free radical stability. Significant deviations from "normal" behaviour are observed for benzophenones substituted by both electron-donating and electron-withdrawing substituents. These deviations are attributed to merostabilization of the radical-like species, and an empirical approach designed to evaluate the importance of this effect is developed. Abinitio calculations of molecular orbital energies in meta- and para-substituted benzaldehydes are used to evaluate the substituent effects on E1/2red and ETn,π* in terms of the effect on the energies of the n- and π*-orbitals.

Halbstufen-Reduktionspotentiale Bor-substituierter Benzolderivate / Half-Wave Reduction Potentials of Boron Substituted Benzene Derivatives

1971 ◽  
Vol 26 (6) ◽  
pp. 525-528 ◽  
Author(s):  
Hans Bock ◽  
Werner Fuss
Keyword(s):  
Molecular Orbital ◽  
Coupling Constants ◽  
Radical Anions ◽  
Benzene Derivatives ◽  
Reduction Potentials ◽  
Half Wave ◽  
Wave Reduction

The reversible one-electron insertion into mono- and 1,4-di-substituted benzene derivatives is favored by dialkoxyboron and especially by dialkylboron groups. The assumption that it should be the symmetric e2u benzene molecular orbital which is occupied in the resulting radical anions can be supported by comparison of ESR coupling constants.

Correlations of substituent effects on proton and fluorine chemical shifts with inverse ionization potentials

1967 ◽  
Vol 45 (24) ◽  
pp. 3143-3151 ◽  
Author(s):  
T. Schaefer ◽  
F. Hruska ◽  
H. M. Hutton
Keyword(s):  
Electric Fields ◽  
Chemical Shifts ◽  
Substituent Effects ◽  
Group Iv ◽  
The Other ◽  
Ionization Potentials ◽  
Time Dependent ◽  
Practical Application ◽  
Methyl Proton ◽  
Proton Chemical Shifts

The fluorine and proton chemical shifts in some geminally disubstituted vinylidene fluorides and ethylenes are discussed. For these compounds, at least, there are difficulties with an interpretation based on intramolecular time-dependent electric fields. On the other hand, the shifts correlate with the inverse ionization potentials of the substituents, indicating a paramagnetic effect arising from the second term in Ramsey's expression. It is suggested that the effect operates via the bonds and not across space. Methyl proton shifts in a series of substituted methyl compounds of group IV, V, and VI elements show similar correlations. A practical application of the correlation to spectral analysis problems is given.

Electrochemical evaluation of electron acceptor materials

1984 ◽  
Vol 62 (10) ◽  
pp. 1877-1885 ◽  
Author(s):  
R. O. Loutfy ◽  
C. K. Hsiao ◽  
B. S. Ong ◽  
B. Keoshkerian
Keyword(s):  
Electron Acceptor ◽  
Methylene Chloride ◽  
Energy Levels ◽  
Mercury Electrode ◽  
Transport Processes ◽  
Reduction Potentials ◽  
Half Wave ◽  
Intermediate Anion ◽  
Wave Reduction ◽  
Anion Radicals

The electrochemical half-wave reduction potential (E1/2) of 33 electron acceptor molecules in dry methylene chloride has been measured by cyclic voltammetry (CV) at a mercury electrode. The differences in E1/2 values for the reversible reduction to the corresponding anion radicals reflect the electronic influence of the substituent at different ring positions.The measurements of the half-wave reduction potentials provided a convenient method for determining the conducting energy levels of the electron relay molecules in condensed media. Repetitive potential cycle measurements provided information on the chemical stability and cyclability of the intermediate anion radicals formed during electron transport processes.

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