Spectra Of Radical Anions Research Articles

EPR spectra of anion radicals of certain alkyl-substituted polysilanes

1. A hyperfine interaction of the unpaired electron in the anion radical\(\left[ {(C_2 H_5 )_2 Si} \right]_6^ \bullet - \) with silicon and carbon atoms was detected. 2. The formation of anion radicals in the reduction of [CH3C2H5Si]6 and (CH3)3SiSi(CH3)2Si(CH3)2Si(CH3)2 Si(CH3)3 was established according to the EPR spectra.

Linewidth Effects in the ESR Spectra of 2,2′-Dinitrodiphenyl Radical Anion Obtained by Alkali Metal Reduction

The ESR spectra of anion radicals, obtained by reduction of 2,2′dinitrodiphenyl with lithium, sodium, and potassium in dimethoxyethane (DME) and tetrahydrofuran (THF), in the temperature range +50°– − 80°C, are discussed. The two nitrogen couplings are not equivalent in the anion radical obtained by lithium reduction, while they are equal in the case of sodium and potassium reduction in both DME and THF. Anomalous linewidth behavior is observed in all these spectra which depend on temperature and solvent, as well as the cation. Freed and Fraenkel's relaxation-matrix theory is used to explain the observed linewidth behavior, taking into account the metal-ion exchange between the two nitro groups. Such pronounced variation in linewidth, which has not been hitherto reported in the metal reduction of dinitro compounds, is attributed to the favorable spatial disposition of the nitro groups in 2,2′-dinitrodiphenyl.

Electron Spin Resonance of Anion Radicals of N-Alkyl Phthalimides and Aromatic Acid Anhydrides

Abstract The ESR spectra of anion radicals of N-methyl, N-ethyl, and N-n-butyl phthalimides, naphthalic acid anhydride, and pyromellitic acid anhydride were measured in acetonitrile. Both the electrolytic and alkali metal reduction methods were used for the radical generation. The spin densities of these anion radicals were then calculated by McLachlan’s method; the calculated results were partly in agreement with the experimental data. Satellite lines due to three kinds of 13C nuclei in the pyromellitic acid anhydride anion radical were observed; one of these splitting constants was assigned to the position 1.

EPR spectra of anion radicals of ?,??-azoisobutyro-dinitrile and the diethyl ester of azoacetic acid

1. The EPR spectra of the anion radicals ofα,α′-azoisobutyrodinitrile and the diethyl ester of azoacetic acid were studied. 2. In the formula describing the interaction of the unpaired electron with the nitrogen nucleus, the value of the polarization parameter for the 2s-electrons of the nitrogen atoms, due to the spin density on the nitrogen atom, possesses a value of 9.8 Oe for the sp2-hybridized carbon atom next to the nitrogen, and 5.3 Oe for the sp3-state.

EPR spectra of radical anions obtained in the electrochemical reduction of nitrocyclopropane, nitroalkanes, and nitroalkylenes

EPR spectra of radical anions obtained in the electrochemical reduction of nitrocyclopropane, nitroalkanes, and nitroalkylenes

EPR spectra of anion radicals containing a cyclopropyl group

1. The delocalization of the unpaired electron on the cyclopropyl group in the phenylcyclopropane anion radical was detected by the EPR method. 2. On the basis of the EPR spectra of alkyl and cyclopropyl ketyls it was shown that the cyclopropyl group is more electrophilic.

Temperature Dependence of ESR Linewidths of Some Nitrobenzene Anion Radicals

Electron spin resonance spectra of anion radicals of nitrobenzene and p-nitrobenzoic acid in dimethylformamide and of p-nitrophenol in dimethylformamide and acetonitrile have been obtained over a range of temperatures. Linewidths have been measured and the variations among them are discussed in terms of the Freed—Fraenkel theory. It is concluded that the anisotropy of molecular tumbling must be considered for these systems, but a complete analysis has not been made.

Electron Spin Resonance Study of the Sym-Trinitrobenzene Anion and Related Radicals

The electron spin resonance spectra of anion radicals generated by the electrolytic reductions of sym-trinitrobenzene, trinitromesitylene, trinitrobenzoic acid, trinitrotoluene, trinitroanisole, picramide, and the picrate ion are reported and discussed. Measurements were carried out in three solvents; dimethylformamide, dimethylsulfoxide, and acetonitrile. In addition, perturbations in the spectrum of the trinitrobenzene anion produced by the presence of various monovalent and divalent cations were studied. The trinitrobenzene and trinitromesitylene anions show an alternating linewidth effect which increases as the interaction between the anion and its environment increases. This effect implies correlated fluctuations in the spin densities of three equivalent nitrogroups.