Theory of Line Widths in Electron Spin Resonance Spectra: Motion of Methyl Groups

1964 ◽  
Vol 86 (17) ◽  
pp. 3477-3484 ◽  
Author(s):  
Jack H. Freed ◽  
George K. Fraenkel
Keyword(s):  
Electron Spin Resonance ◽  
Electron Spin ◽  
Methyl Groups ◽  
Spin Resonance ◽  
Line Widths

A PARAMAGNETIC RESONANCE STUDY OF HINDERED DIARYLMETHYL RADICALS AND RELATED COMPOUNDS: I. ANALYSIS OF THE SPECTRA

1966 ◽  
Vol 44 (12) ◽  
pp. 1387-1395 ◽  
Author(s):  
H. R. Falle ◽  
F. C. Adam
Keyword(s):  
Electron Spin Resonance ◽  
Electron Spin ◽  
Ion Pair ◽  
Coupling Constants ◽  
Methyl Groups ◽  
Steric Repulsion ◽  
Paramagnetic Resonance ◽  
Spin Resonance ◽  
Phenyl Rings ◽  
Related Compounds

Several ortho-substituted radicals of the benzhydryl type and a variety of diaryl ketyls have been studied through the nuclear hyperfine structure of their electron spin resonance spectra. A strong similarity is found between the spectra of a given ketyl and its hydrocarbon analogue. This suggests that when ketones are reduced, a very tight ion pair is formed between the ketyl anion and its cation. Although the coupling constants of the protons vary with different reducing agents, larger variations are observed when bulky groups are substituted into ortho positions. These larger changes are attributed to a forced internal rotation of the phenyl rings. The distortion results from the steric repulsion between the ortho groups. The effect of 'buttressing' of ortho methyl groups is also studied. Deuterium and 13C substitutions have been effected in some of the compounds.

Electron Spin Resonance Line-Widths in Solutions of Copper and Silver Dithiocarbamates

Nature ◽  
1961 ◽  
Vol 190 (4772) ◽  
pp. 258-259 ◽  
Author(s):  
ROLAND AASA ◽  
RUNE PETTERSSON ◽  
TORE VÄNNGÅRD
Keyword(s):  
Electron Spin Resonance ◽  
Electron Spin ◽  
Resonance Line ◽  
Electron Spin Resonance Line ◽  
Spin Resonance ◽  
Line Widths

Electron spin resonance studies of radiation damage. Part I. An alternating linewidth effect for the (CH3)2ĊOH radical in gamma-irradiated acetone at low temperatures

1968 ◽  
Vol 46 (6) ◽  
pp. 1029-1031 ◽  
Author(s):  
F. P. Sargent
Keyword(s):  
Electron Spin Resonance ◽  
Temperature Dependence ◽  
Radiation Damage ◽  
Electron Spin ◽  
Low Temperatures ◽  
Methyl Groups ◽  
Oh Groups ◽  
Restricted Rotation ◽  
Spin Resonance ◽  
Gamma Irradiated

The e.s.r. spectrum of the (CH3)2ĊOH radical showed a drastic temperature dependence of linewidth in the range −196 to −100 °C, this being particularly pronounced for the M1 = ±2 lines. Possible mechanisms are discussed in terms of restricted rotation of the methyl groups and of the OH groups.

An electron spin resonance study of the oxidation of benzene solutions of phenols by means of silver oxide

1968 ◽  
Vol 302 (1470) ◽  
pp. 329-330
Keyword(s):  
Electron Spin Resonance ◽  
Electron Spin ◽  
Silver Oxide ◽  
Electron Spin Resonance Study ◽  
Methyl Groups ◽  
Substituted Phenols ◽  
Heterogeneous Oxidation ◽  
Spin Resonance ◽  
Oxidation Of Benzene ◽  
Spin Resonance Study

The heterogeneous oxidation of some substituted phenols has been studied by means of electron spin resonance. Strong signals, observed during the oxidation of the phenols with a free para -position, are due to secondary radicals derived from C 4 —O linked dimeric and polymeric phenols ( A ) are not to substituted 4, 4'-di-pheno-semiquinones ( B ). Special attention has been given to the oxidation of 2, 6-dimethylphenol which yields a radical with non-equivalent methyl groups. The e. s. r. spectra of the secondary radicals from some 4-substituted 2, 6-dimethylphenol are identical to each other and to that from 2, 6-dimethylphenol itself. This indicates that in these radicals the para -substituent had been displaced by an aryloxy group. The ease of this displacement can be determined by use of the flow technique.

THE ELECTRON-SPIN RESONANCE SPECTRA OF SOME METHYLATED ANTHRASEMIQUINONES: EVIDENCE FOR RESTRICTED ROTATION

1965 ◽  
Vol 43 (5) ◽  
pp. 1553-1559 ◽  
Author(s):  
R. M. Elofson ◽  
K. F. Schulz ◽  
B. E. Galbraith ◽  
R. Newton
Keyword(s):  
Electron Spin Resonance ◽  
Electron Spin ◽  
Steric Hindrance ◽  
Methyl Groups ◽  
Redox Potentials ◽  
Restricted Rotation ◽  
Spin Resonance

The hyperfine electron-spin resonance spectra of a number of methyl-substituted 9,10-anthrasemiquinones have been determined. The spectra have been analyzed by computer techniques, and splitting constants have been assigned for all protons. The results indicate that, while the parent quinones are essentially free of steric hindrance, the methyl groups in the α position of the reduced quinones are not free to rotate. The methyl groups in the β position of the semiquinones show normal hyperconjugative behavior. These results are consistent with the different redox potentials of these compounds revealed in a previous study.

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