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 of fluorine-substituted nitro-aromatic anion radicals

1968 ◽  
Vol 46 (24) ◽  
pp. 3847-3856 ◽  
Author(s):  
P. H. H. Fischer ◽  
H. Zimmermann
Keyword(s):  
Electron Spin Resonance ◽  
Electron Spin ◽  
Half Life ◽  
Coupling Constants ◽  
Acetonitrile Solution ◽  
Spin Resonance ◽  
Related Compounds ◽  
Nitro Benzene ◽  
Nitro Aromatic ◽  
Anion Radicals

Electron spin resonance spectra have been observed for anion radicals derived from 2-fluoro-nitro-benzene, 3-fluoro-nitrobenzene, 2,4-difluoro-nitrobenzene, 2,5-difluoro-nitrobenzene, 4-fluoro-2-nitro-phenol, 2-fluoro-6-nitrophenol, and 3-fluoro-6-nitrophenol. All radicals were generated electrolytically in dimethoxyethane/acetonitrile solution, acetonitrile, or dimethylformamide. The radicals are generally quite stable with the exception of those from 2-fluoro-6-nitrophenol and 3-fluoro-6-nitrophenol, the latter decaying with a half-life of approximately 6 min. All spectra can be interpreted completely, and coupling constants are assigned by comparison to related compounds and consistency arguments.

A comparison of electron spin resonance α- and β-hyperfine coupling constants in para-substituted α-phenethyl radicals

1986 ◽  
Vol 64 (4) ◽  
pp. 769-772 ◽  
Author(s):  
Donald R. Arnold ◽  
A. Martin de P. Nicholas ◽  
Kent M. Young
Keyword(s):  
Electron Spin Resonance ◽  
Experimental Evidence ◽  
Linear Relationship ◽  
Electron Spin ◽  
Hyperfine Coupling ◽  
Coupling Constants ◽  
Hyperfine Coupling Constants ◽  
Spin Resonance ◽  
Benzyl Radicals ◽  
Spin Delocalization

The linear relationship between the electron spin resonance hyperfine coupling constants (hfc) of the α- and β-hydrogens of para-substituted α-phenethyl radicals provides experimental evidence that the magnitude of both the α- and β -hfc is determined largely by the extent of spin delocalization in these benzylic systems. The [Formula: see text] scale, developed using substituted benzyl radicals, is shown to apply to phenethyl radicals as well.

Paramagnetic resonance and optical absorption of trapped holes and electrons in irradiated KCI: Ag

1963 ◽  
Vol 271 (1345) ◽  
pp. 243-267 ◽  
Keyword(s):  
Electron Spin Resonance ◽  
Low Temperature ◽  
Optical Absorption ◽  
Electron Spin ◽  
Optical Absorption Spectra ◽  
Paramagnetic Resonance ◽  
Spin Resonance ◽  
Impurity Ions ◽  
Temperature Irradiation ◽  
Positive Holes

The electron spin resonance and optical absorption spectra of crystals of KCl containing silver impurity ions were examined after the crystals had been X -irradiated at 77 °K. It is shown that the silver impurity ions act as traps for both electrons and positive holes. A description is given of the annealing behaviour of the crystals after low-temperature irradiation.

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