Journal ArticleDOI
Analysis of the Electron Spin Resonance Spectra of Aromatic Nitrosubstituted Anion Radicals
TLDR
In this paper, a good quantitative correlation was obtained between the calculated spin densities and the experimental proton hyperfine splittings for most of the compounds studied, and an equation was formulated which gave excellent predictions of the splitting from N14 nuclei in the nitro groups.Abstract:
Molecular orbital calculations using the Huckel LCAO theory and the approximate configuration interaction treatment suggested by McLachlan have been performed on a large series of nitrosubstituted aromatic anion radicals By properly adjusting the Coulomb and resonance integrals for the nitro group, a good quantitative correlation is obtained between the calculated spin densities and the experimental proton hyperfine splittings for most of the compounds studied Procedures are developed to account for the variations in hyperfine splittings with different solvents, and an equation is formulated which gives excellent predictions of the splitting from N14 nuclei in the nitro groups In addition, the calculations provide a basis for the qualitative discussion of the effects of sterically hindered nitro groups on the hyperfine splittings, and of the apparently anomalous spin densities and linewidth variations in some of the meta‐dinitrobenzene anions Polarographic half‐wave potentials are also correlated withread more
Citations
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THEORETICAL INTERPRETATION OF CARBON-13 HYPERFINE INTERACTIONS IN ELECTRON SPIN RESONANCE SPECTRA. Technical Note Report No. 9
M. Karplus,G.K. Fraenkel +1 more
TL;DR: In this article, a quantitative theory of the isotropic electron−nuclear spin interactions of carbon 13 in pi-electron radicals is presented and applied to the hyperfine splittings observed in the electron spin resonance spectra of these substances.
Journal ArticleDOI
On the spin-forbiddeness of gas-phase ion–molecule reactions: a fruitful intersection of experimental and computational studies
TL;DR: In this article, the effects of spin changes on the efficiencies and product distributions of gas-phase ion-molecule reactions are analyzed, and the examples discussed include metal- as well as non-metal containing systems, with some emphasis on various types of bond activation by "naked" transition-metal cations and structurally simple cationic transition metal oxides.
Journal ArticleDOI
Anisotropic Rotational Diffusion and Electron Spin Resonance Linewidths
TL;DR: In this paper, the authors extended the theory of ESR linewidths for dilute solutions of free radicals developed by Freed and Fraenkel to cover the possibility that the rotational motions of the free radicals are anisotropic.
Journal ArticleDOI
Electron Spin Resonance Study of the Pairing Theorem for Alternant Hydrocarbons : 13C Splittings in the Anthracene Positive and Negative Ions
TL;DR: The pairing theorem for alternant hydrocarbons predicts that the pi-electron spin densities at corresponding positions of the negative and positive ions of a hydrocarbon should be the same, but significant differences have been found previously for the proton hyperfine splittings in electron spin resonance spectra as discussed by the authors.
Journal ArticleDOI
Dynamic Frequency Shifts and the Effects of Molecular Motions in the Electron Spin Resonance Spectra of Dinitrobenzene Anion Radicals
TL;DR: In this paper, the electron spin resonance spectra of the m−dinitrobenzene anion radical and several of its derivatives were examined under a variety of conditions in order to study the alternating linewidth effect and, for the first time, the associated dynamic second-order frequency shifts.
References
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Journal ArticleDOI
Self-consistent field theory of the electron spin distribution in π-electron radicals
TL;DR: In this paper, the Pariser and Parr theory was used to derive the spin density in a single determinant wave function with one unpaired electron, and 2n paired ones in n orbitals.
Journal ArticleDOI
Theory of Linewidths in Electron Spin Resonance Spectra
Jack H. Freed,George K. Fraenkel +1 more
TL;DR: In this article, it was shown that a composite line arising from a set of degenerate nuclear-spin states should, in general, consist of a sum of superimposed lines of Lorentzian shape with different widths rather than a single line with an over-all shape.
Journal ArticleDOI
Theoretical Interpretation of Carbon‐13 Hyperfine Interactions in Electron Spin Resonance Spectra
TL;DR: In this paper, a quantitative theory of the isotropic electron−nuclear spin interactions of carbon 13 in pi-electron radicals is presented and applied to the hyperfine splittings observed in the electron spin resonance spectra of these substances.
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Electron Spin Resonance and Polarographic Investigation of Substituted Nitrobenzene Negative Ions
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