1H,13C and77Se NMR study of tetraselenafulvalene derivatives supported by novel H(Se)C and H(C)Se triple-resonance experiments at natural abundance

2008 ◽  
Vol 46 (2) ◽  
pp. 150-155 ◽  
Author(s):  
Michal Maloň ◽  
Tatsuro Imakubo ◽  
Hiroyuki Koshino
Keyword(s):  
Natural Abundance ◽  
Triple Resonance ◽  
Triple Resonance Experiments ◽  
Nmr Study

scholarly journals Signs of proton–proton and proton–fluorine spin–spin coupling constants in 2-fluoro-3-methylpyridine. Sigma and pi contributions to coupling in a nitrogen heterocycle

1969 ◽  
Vol 47 (9) ◽  
pp. 1507-1514 ◽  
Author(s):  
T. Schaefer ◽  
S. S. Danyluk ◽  
C. L. Bell
Keyword(s):  
Nitrogen Atom ◽  
Long Range ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Nitrogen Heterocycle ◽  
Triple Resonance ◽  
Triple Resonance Experiments ◽  
Proton Proton ◽  
Spin Coupling Constants ◽  
Spin Spin Coupling

The signs of all proton–proton and proton–fluorine spin–spin coupling constants in 2-fluoro-3-methylpyridine have been determined by double and triple resonance experiments. The signs of the longrange coupling constants, JH,CH3 and JF,CH3 are the same as in fluorotoluene derivatives. Their magnitudes are consistent with the assumption that the nitrogen atom primarily polarizes the σ bonds in the molecule, leaving the π contribution to the long-range coupling relatively unaffected.

Collisional Transfer of Energy in Ammonia; Some Triple Resonance Experiments

1973 ◽  
Vol 28 (10) ◽  
pp. 1703-1706 ◽  
Author(s):  
Harold Jones ◽  
Achim Eyer
Keyword(s):  
Microwave Power ◽  
Triple Resonance ◽  
Population Changes ◽  
Triple Resonance Experiments ◽  
Collisional Transitions

Infrared-microwave-microwave triple resonance experiments in ammonia are reported. The power modulated P13 line of a N2O laser was used to pump the ν2[Q(8,7)] transition of ammonia. The dependance of the intensity of the collisionally induced signals produced at the (7,7), (6,6), (5,5) and (4,4) microwave transitions on c. w. microwave power applied to the (8,7) transition was measured. From the null signal observed for the (7,7) transition when the (8,7) transition was saturated, it was concluded that population changes produced in the (7,7) levels occur predominently via direct collisional transitions which are strongly parity sensitive and that other processes have little contribution. The signals observed for the (6,6), (5,5) and (4,4) are produced by processes which are largely insensitive to parity.

ESR and ENDOR Investigations of Adrenochrome Semiquinone and Related Amino-1,2-Benzosemiquinone Radicals

1985 ◽  
Vol 40 (7-8) ◽  
pp. 531-534 ◽  
Author(s):  
Hartmut B. Stegmann ◽  
Hoang Dao-Ba ◽  
Klaus Scheffler ◽  
Martin G. Peter
Keyword(s):  
Hyperfine Structure ◽  
Spin Density ◽  
Ethanol Solution ◽  
Coupling Constants ◽  
Triple Resonance ◽  
Triple Resonance Experiments ◽  
Proton Coupling ◽  
Endor Spectroscopy ◽  
Nitrogen Coupling

Abstract Dimethyl or diethylamine reacts very smoothly in ethanol solution with catechols to the corresponding aminoquinones. The paramagnetic intermediates, the semiquinones, are investigated by ESR and ENDOR spectroscopy using the spin stabilisation technique with diarylthallium cations. The spectra of these radicals show clearly the thallium and nitrogen coupling and the hydrogen hyperfine structure. For some examples the signs of the proton coupling constants are determined by TRIPLE resonance experiments. The results indicate a negative spin density in one position of the unsymmetrically substituted radical 3. With the results obtained for the monocyclic aminosemiquinones the hyperfine structure of the adrenochrome semiquinone is analysed.

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