H(C)P and H(P)C triple-resonance experiments at natural abundance employing long-range couplings

2007 ◽  
Vol 45 (9) ◽  
pp. 770-776 ◽  
Author(s):  
Michal Maloň ◽  
Hiroyuki Koshino
Keyword(s):  
Long Range ◽  
Natural Abundance ◽  
Triple Resonance ◽  
Triple Resonance Experiments

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.

P.M.R. spectra of heteroaromatic molecules containing bridgehead nitrogen atoms. I. Tetrazolo[1,5-a]quinoline and 5-Methyltetrazolo[1,5-a]quinoline

1976 ◽  
Vol 29 (4) ◽  
pp. 799 ◽  
Author(s):  
ML Heffernan ◽  
GM Irvine
Keyword(s):  
Nitrogen Atom ◽  
Long Range ◽  
Coupling Constants ◽  
Triple Resonance ◽  
Relative Sign ◽  
Coupling Constant ◽  
Triple Resonance Experiments ◽  
Aromatic Molecules ◽  
Bridgehead Nitrogen

This paper is the first of a series dealing with the analysis of the 100-MHz p.m.r, spectra of hetero-aromatic molecules containing a bridgehead nitrogen atom as part of the conjugated system, e.g. pyrrolo[l,2-a]quinoline. The spectra of the aza-substituted derivatives tetrazolo[l,5-a]quinoline and 5-methyltetrazolo[l,5-a]quinoline in Me2SO and CDCl3 solutions are analysed in detail. Special attention was directed to the determination of the long-range inter-ring coupling constants and their relative signs by multiple-resonance techniques. The analysis of the spectrum of the 5-methyl compound was considerably simplified by decoupling of the methyl protons from the remainder. Evidence was found for a five-bond long-range coupling constant, J4,6, and a seven-bond coupling constant, J4,8 both having a magnitude around 0.3 Hz. Selective double and triple resonance experiments indicated that the relative sign of both of these long-range coupling constants was positive.

High Resolution 13C Spectrum and Long-Range 13C,H Couplings in 2-Pyrone

1975 ◽  
Vol 53 (13) ◽  
pp. 1980-1983 ◽  
Author(s):  
A. A. Chalmers ◽  
K. G. R. Pachler
Keyword(s):  
High Resolution ◽  
Long Range ◽  
Natural Abundance ◽  
Related Compounds

The natural abundance 13C n.m.r. spectrum of 2-pyrone has been analyzed by the 13C–{1H} SPI technique. The magnitudes and signs of all long-range 13C,H couplings have been obtained and are compared with those of related compounds.

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.

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