661. The electron spin resonance spectra of γ-irradiated fumaric acid

Cook, Raymond; Rowlands, J. R.; Whiffen, D. H.

doi:10.1039/jr9630003520

Cited by 14 publications

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“…These latter studies showed that the sign of the fluorine coupling in the C-F fragment is positive, in contrast to the negative coupling in the C-H fragment. This may be taken as evidence for electron delocalization between carbon and fluorine; similar conclusions were reached in a single crystal study of x-irradiated mono-fluoracetamide [8].…”

Section: Introductionsupporting

confidence: 73%

“…calculations using the method due to McLachlan with appropriate molecular orbital parameters for fluorine [8] and the nitro group [19]. The resulting spin densities are shown in the table.…”

Section: Theorymentioning

confidence: 99%

“…in equation (2) the first term arises from spin polarization of the C-F a bonding electrons due to unpaired spin on the carbon atom and the second term represents the spin polarization of fuorine ls and 2s electrons due to spin density in a 2p~r orbital on fluorine; one expects Qc to be negative and QF to be positive. Accurate values of the constants are not yet available although a number of estimates have been made [7,8,20].…”

Section: Introductionmentioning

confidence: 99%

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Electron resonance studies of fluorine hyperfine interactions

1965

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Section: Introductionsupporting

confidence: 73%

Section: Theorymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Electron resonance studies of fluorine hyperfine interactions

1965

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“…In toluene and 4-fluorotoluene, 6~ measured as -0.59 Hz, implying a larger magnitude of QCF in (H,CH3) and 6~ (F,CH3) are a measure of QHcH and the 4FS than in 4-fluorotoluene. The methyl group is a n electron composite (34,36) Q: F at the position para to the methyl donor, whereas the vinyl group is electronically neutral (37). group (26,35).…”

Section: ~4mentioning

confidence: 99%

¹H and ¹⁹F NMR conformational studies of the monofluorostyrenes in solution. Comparison with theory and vapor phase behavior

Schaefer¹,

Sebastian²

1990

Can. J. Chem.

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. Can. J. Chem. 68, 1383 (1990). The parameters for the high resolution 'H and "F NMR spectra of 2-, 3-, and 4-fluorostyrene are reported for solutions in CS, and acetone-d6 at 300 K. The populations of the planar cis and trans conformers of 2-and 3-fluorostyrene are deduced from the long-range coupling constants involving the meta and a protons. These populations are insensitive to solvent and appear to be in reasonable agreement with previous 6-3 1G MO computations for the free molecule; they are also compared with populations deduced from recent rotational and vibronic spectra. The long-range coupling constants for the protons of 4-fluorostyrene imply an internal barrier to rotation about the exocyclic carbon-carbon bond very similar to that in styrene, in agreement with the 6-3 1 G results. The signs of the coupling constants involving "F and the protons in the side chain are reported and discussed in terms of coupling mechanisms for the three molecules. An earlier surmise, of a positive a electron contribution to the coupling constant over six bonds in an all-trans arrangement, is confirmed for the meta and trans-p protons in 3-fluorostyrene.Key words: monofluorostyrenes, 'H and "F NMR, conformations, long-range coupling mechanisms, MO calculations of internal barriers.TED SCHAEFER et RUDY SEBASTIAN. Can. J . Chem. 68, 1383 (1990).On a dttermink les paramktres pour les spectres RMN a haute rksolution du 'H et du "F des 2-, 3-et 4-fluorostyrknes, en solutions dans le CS2 et dans I'acktone-d6, a 300 K. On a dCduit les populations des conformkres plans cis et trans prtsents dans les 2-et 3-fluorostyrknes en se basant sur les constantes de couplage a longue distance impliquant les protons me'ta et a . Ces populations sont insensibles la nature des solvants et elles semblent en bon accord avec des prkvisions faites antkrieurement en se basant sur des calculs d'OM effectuCs au niveau 6-31G, sur la molCcule libre; on a aussi compark ces rCsultats avec les populations qui ont rkcernment Ct C dCduites de spectres de rotation et de vibration. Les constantes de couplage a longue distance qui sont observkes dans le 4-fluorostyrkne impliquent que la barrikre interne la rotation autour de la liaison carbone-carbone exocyclique est trks semblable a celle qui est observke dans le styrkne; cette conclusion est en accord avec les prkdictions faites a l'aide de calculs au niveau 6-3 I G. On rapporte aussi les signes des constantes de couplage entre le "F et les protons de la chaine latCrale et on en discute en fonction de mkcanismes de couplage opCrant dans ces trois moltcules. Pour les protons me'ta et trans-p du 3-fluorostyrkne, on confirme la prkdiction antCrieure a l'effet que, dans un arrangement complktement trans, il existe une contribution a klectronique positive a la constante de couplage travers six liaisons.

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“…Therefore, it is interesting to investigate x-or g-damage in the [TMAHF-FA]. It is also fruitful to study g-irradiated [TMAHF-FA] compound due to its potential polymerization in the solid state considering the study of Cook et al [6] where they have shown that polymerization occurs in g-irradiated fumaric acid through observing that the dominant radical presents after the irradiation is of the forms HO 2 CCH(R)Ċ HCO 2 H and HO 2 CCH 2 Ċ HCO 2 H.…”

Section: Introductionmentioning

confidence: 99%

Structural, spectroscopic characterization and EPR studies of tetramethylammonium-hydrogen fumarate–fumaric acid complex

Bozkurt¹,

Uçar²,

Kartal³

et al. 2008

Journal of Physics and Chemistry of Solids

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661. The electron spin resonance spectra of γ-irradiated fumaric acid

Cited by 14 publications

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Electron resonance studies of fluorine hyperfine interactions

Electron resonance studies of fluorine hyperfine interactions

¹H and ¹⁹F NMR conformational studies of the monofluorostyrenes in solution. Comparison with theory and vapor phase behavior

Structural, spectroscopic characterization and EPR studies of tetramethylammonium-hydrogen fumarate–fumaric acid complex

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661. The electron spin resonance spectra of γ-irradiated fumaric acid

Cited by 14 publications

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Electron resonance studies of fluorine hyperfine interactions

Electron resonance studies of fluorine hyperfine interactions

1H and 19F NMR conformational studies of the monofluorostyrenes in solution. Comparison with theory and vapor phase behavior

Structural, spectroscopic characterization and EPR studies of tetramethylammonium-hydrogen fumarate–fumaric acid complex

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¹H and ¹⁹F NMR conformational studies of the monofluorostyrenes in solution. Comparison with theory and vapor phase behavior