Organometallic peroxy radicals. 4. Electron spin resonance spectra of the radicals produced by reaction of organophosphorus(IV) and organoarsenic(IV) radicals with 17O-enriched oxygen

1978 ◽  
Vol 56 (16) ◽  
pp. 2163-2166 ◽  
Author(s):  
J. A. Howard ◽  
J. C. Tait
Keyword(s):  
Electron Spin Resonance ◽  
Hyperfine Coupling ◽  
Coupling Constants ◽  
Peroxy Radicals ◽  
Factors Associated ◽  
Spin Resonance ◽  
Anisotropic Hyperfine ◽  
Unpaired Spin ◽  
Small Change ◽  
Alkylperoxy Radicals

It bas been shown that some tetra-coordinate phosphorus and arsenic radicals combine with oxygen to give peroxy radicals. The magnitude of the oxygen isotropic and anisotropic hyperfine coupling constants indicates that nearly all the unpaired spin is associated with the two oxygen nuclei with ca. 60% on the terminal oxygen. The large isotropic g-factors associated with Group VB peroxy radicals relative to alkylperoxy radicals is attributed to a small change in geometry of the peroxy function.The radicals with ap ∼ 9 G obtained during the reaction of photochemically generated tert-butoxy radicals with trialkylphosphites in the presence of oxygen are secondary species which appear to contain only one oxygen atom.

Electron spin resonance study of γ-irradiated ethyleneimine in the solid state

1969 ◽  
Vol 47 (14) ◽  
pp. 2601-2603 ◽  
Author(s):  
D. Cordischi ◽  
R. Di Blasi
Keyword(s):  
Electron Spin Resonance ◽  
Electron Spin ◽  
Hyperfine Coupling ◽  
Glassy State ◽  
Coupling Constants ◽  
Electron Spin Resonance Study ◽  
Γ Irradiation ◽  
Spin Resonance ◽  
Anisotropic Hyperfine ◽  
Spin Resonance Study

The electron spin resonance (e.s.r.) study of the ethyleneimine in polycrystalline and glassy state shows that the radical [Formula: see text] is formed by γ-irradiation at 77 °K. The features of the e.s.r. spectrum of this radical are discussed in terms of the isotropic and anisotropic hyperfine coupling constants of the hydrogen and nitrogen nuclei. The effects of bleaching the γ-irradiated sample with visible and ultraviolet light are also reported.

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.

Nitroxide derivatives of acetylacetone as spin-labelled ligands

1981 ◽  
Vol 59 (1) ◽  
pp. 156-163 ◽  
Author(s):  
D. Plancherel ◽  
D. R. Eaton
Keyword(s):  
Electron Spin Resonance ◽  
Metal Complex ◽  
Electron Spin ◽  
Hyperfine Coupling ◽  
Esr Spectra ◽  
Enol Form ◽  
Coupling Constants ◽  
Spin Resonance ◽  
Steric Factors ◽  
Derivatives Of

Electron spin resonance spectra are reported from a number of radicals derived from 2,4-pentadione substituted at the 3 position with nitroxide-containing groups. If the substituent is t-butyl nitroxide no metal complexes are formed. This is attributed to steric factors which prevent the formation of the enol form of the β-diketone. If the substituent is trifluoromethyl nitroxide two types of metal complex have been observed. The esr spectra of the first type are very similar to that of the uncomplexed radical. Such complexes are formed with Co(III) and Al(III). The esr spectra of the second type show considerably increased 14N and 19F hyperfine coupling constants and in some cases large couplings to the metal nucleus. Complexes for the second type have been observed with Pd(II), Pt(II), and Rh(III). The possible structures of these radicals are discussed.

E.P.R. studies of the anions of some peri-alkylnaphthalenes

1972 ◽  
Vol 25 (11) ◽  
pp. 2353 ◽  
Author(s):  
RFC Claridge ◽  
BM Peake
Keyword(s):  
Electron Spin Resonance ◽  
Molecular Orbital ◽  
Electron Spin ◽  
Hyperfine Coupling ◽  
Inductive Effect ◽  
Coupling Constants ◽  
Radical Anions ◽  
Hyperfine Coupling Constants ◽  
Spin Resonance ◽  
Aliphatic Substituent

The hyperfine coupling constants for the radical anions of 2,3-dihydro- phenalene (perinaphthane) and 7,8,9,l0-tetrahydrocyclohepta[de]naphthalene have been determined from analysis of the electron spin resonance spectra in solution. The results are compared with data from other mono- and di-peri- substituted naphthalenes. A simple H�ckel molecular orbital treatment is used to describe the inductive effect of the aliphatic substituent.

Substituent effects on benzyl radical hyperfine coupling constants. Part 2. The effect of sulphur substituents

1984 ◽  
Vol 62 (6) ◽  
pp. 1164-1168 ◽  
Author(s):  
Danial D. M. Wayner ◽  
Donald R. Arnold
Keyword(s):  
Electron Spin Resonance ◽  
Spin Density ◽  
Oxidation State ◽  
Esr Spectroscopy ◽  
Hyperfine Coupling ◽  
Substituent Effects ◽  
Coupling Constants ◽  
Benzyl Radical ◽  
Spin Resonance ◽  
Benzyl Radicals

Several 4-substituted benzyl radicals of the general form R(On)SC6H4CH2•(n = 0, 1, 2; R = Me, Ph, Tol, COCH3 OCH3) have been investigated by electron spin resonance (esr) spectroscopy. In general, the ability to delocalize spin density onto the substituent decreases as n increases. The effect of R on the spin density depends on the oxidation state of the sulphur. These trends are explained by considering the sulphur to be either a spin donor or a spin acceptor, depending on the oxidation state. The σ•α values are determined.

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