Measurement of C',C coupling constants in carbon-13 labeled proteins: a new method for the stereospecific assignment of .gamma.-methyl groups in valine residues

1993 ◽  
Vol 115 (17) ◽  
pp. 7878-7879 ◽  
Author(s):  
H. Schwalbe ◽  
A. Rexroth ◽  
U. Eggenberger ◽  
T. Geppert ◽  
C. Griesinger
Keyword(s):  
Coupling Constants ◽  
New Method ◽  
Methyl Groups ◽  
Stereospecific Assignment

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.

scholarly journals Real-time broadband proton-homodecoupled CLIP/CLAP-HSQC for automated measurement of heteronuclear one-bond coupling constants

RSC Advances ◽  
2016 ◽  
Vol 6 (91) ◽  
pp. 87848-87855 ◽  
Author(s):  
István Timári ◽  
Lukas Kaltschnee ◽  
Mária H. Raics ◽  
Felix Roth ◽  
Nicholle G. A. Bell ◽  
...  
Keyword(s):  
Real Time ◽  
Nmr Spectra ◽  
Coupling Constants ◽  
Extra Cost ◽  
New Method ◽  
Measurement Time ◽  
Automated Measurement

A new method is proposed that allows broadband homonuclear decoupled CLIP/CLAP-HSQC NMR spectra to be acquired at virtually no extra cost in measurement time.

Anharmonicity corrections from Coriolis coupling constants

1975 ◽  
Vol 28 (12) ◽  
pp. 2727 ◽  
Author(s):  
TR Ananthakrishnan ◽  
G Aruldhas
Keyword(s):  
Coupling Constants ◽  
New Method ◽  
Coriolis Coupling ◽  
Harmonic Frequencies ◽  
Anharmonicity Constants

A new method is suggested for calculating the ratios of harmonic frequencies for certain types of molecules and their isotopic forms by making use of Coriolis coupling constants. The method applies to cases where there are two distinct degenerate vibrations with the same species. The anharmonicity constants for these vibrations can then be evaluated.

scholarly journals Synthese und spektroskopische Charakterisierung mehrfach silylierter Ethene / Synthesis and Spectroscopic Characterization of Di- and Trisilylethenes

1987 ◽  
Vol 42 (12) ◽  
pp. 1543-1548 ◽  
Author(s):  
H. Schmidbaur ◽  
J. Ebenhöch
Keyword(s):  
Nmr Spectra ◽  
Spectroscopic Characterization ◽  
Coupling Constants ◽  
Methyl Groups ◽  
Coupling Constant ◽  
Catalytic Hydrosilylation

AbstractDi- and trisilylethenes have been prepared by catalytic hydrosilylation of trimethylsilyl-, bis-(trimethylsilyl)- and bis(trichlorosilyl)ethyne and converted into the hydrogenated derivatives by LiAlH4-reduction. The stereochemistry of the products and the effects of substitution of methyl vs. chlorine ligands on the NMR coupling constants J(29Si/1H) have been investigated by analysis of selectively (Me)-decoupled 29Si NMR spectra. From the results it has been concluded, that the catalytic hydrosilylation of silylated ethynes proceeds in a stereospecific syn fashion yielding trans adducts. Substitution of methyl by chlorine at one or two Si-atoms in tris(trimethylsilyl)ethene leads to an increase of the coupling constant J(29Si/1H vinyl) with the chlorinated Si-atoms and reduces the values for those Si-atoms, where the methyl groups are retained.

Vicinal proton-proton coupling constants V. Couplings to methyl groups

1997 ◽  
Vol 91 (2) ◽  
pp. 343-356 ◽  
Author(s):  
By JOAQUIN GUILLEME ◽  
JESUS SAN FABIAN ◽  
ERNESTO DIEZ
Keyword(s):  
Coupling Constants ◽  
Methyl Groups ◽  
Proton Proton ◽  
Proton Coupling ◽  
Vicinal Proton

Zum Mikrowellenspektrum des Isobutyronitrils

1967 ◽  
Vol 22 (4) ◽  
pp. 543-545 ◽  
Author(s):  
G. E. Herberich
Keyword(s):  
Lower Bound ◽  
Internal Rotation ◽  
Barrier Height ◽  
Microwave Spectrum ◽  
Coupling Constants ◽  
Methyl Groups ◽  
Kcal Mole ◽  
Rotational Constants ◽  
Quadrupole Coupling ◽  
Nuclear Quadrupole

The microwave spectrum of isobutyronitrile has been investigated in the region from 5 — 30 GHz. A and C type transitions have been observed. No splittings due to internal rotation of the methyl groups could be detected and a lower bound of 2.6 kcal/mole for the barrier height is established.Values for the rotational constants are 7.940 95 ± 0.000 04, 3.968 039 ± 0.000 010 and 2.901 030 ± 0.000 010 GHz.The nuclear quadrupole coupling constants are χαα=—3.905±0.010 MHz, χbb=2.077±0.02 MHz and χcc=1.828±0.017 MHz.

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