Minimalist Relativistic Force Field: Prediction of Proton–Proton Coupling Constants in 1H NMR Spectra Is Perfected with NBO Hybridization Parameters

2015 ◽  
Vol 80 (10) ◽  
pp. 5218-5225 ◽  
Author(s):  
Andrei G. Kutateladze ◽  
Olga A. Mukhina
Keyword(s):  
Force Field ◽  
1H Nmr ◽  
Nmr Spectra ◽  
1H Nmr Spectra ◽  
Coupling Constants ◽  
Proton Proton ◽  
Proton Coupling

scholarly journals Allylic Proton-Proton Coupling in Stereodefined Alkylidenecyclobutanes and Alkylidenecycopentanes

2019 ◽  
Vol 53 (3) ◽  
Author(s):  
William F. Bailey ◽  
Timo V. Ovaska
Keyword(s):  
Dihedral Angle ◽  
1H Nmr ◽  
Nmr Spectra ◽  
1H Nmr Spectra ◽  
Proton Proton ◽  
Proton Coupling

Analysis of the 1H NMR spectra of eight stereodefined alkylidenecycloalkanes allows determination of the magnitude of allylic coupling in these compounds. In contrast to the trend normally observed, the magnitude of transoid-allylic coupling was found to be invariably greater by ~0.5 Hz than the cisoid-allylic coupling. The larger transoid-allylic coupling may be attributed to the slightly smaller dihedral angle relating allylic =C–C–H plane with the C=C–C plane in the E-isomers.

Structural revision of glabramycins B and C, antibiotics from the fungus Neosartorya glabra by DFT calculations of NMR chemical shifts and coupling constants

RSC Advances ◽  
2015 ◽  
Vol 5 (46) ◽  
pp. 36858-36864 ◽  
Author(s):  
Yang Li
Keyword(s):  
Natural Products ◽  
Dft Calculations ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
Proton Proton ◽  
Structural Revision ◽  
Proton Coupling ◽  
Vicinal Proton ◽  
C Nmr

The 13C NMR spectra and vicinal proton–proton coupling constants of two tricyclic macrolactone natural products were analyzed using computational methods, which resulted in their structural revisions.

Über die Berechnung der 1H-NMR-Spektren linearer Di-aza-acene / On the Calculation of 1H-NMR-Spectra of Linear Di-aza-acenes

1972 ◽  
Vol 27 (10) ◽  
pp. 1164-1165 ◽  
Author(s):  
G. Ege ◽  
H. Vogler
Keyword(s):  
1H Nmr ◽  
Nmr Spectra ◽  
1H Nmr Spectra ◽  
Coupling Constants

It is shown, that the calculation of chemical proton shifts and coupling constants of linear di-aza-acenes within the framework of HMO-theory gives values close to experimental ones.

15N, 13C, and 1H NMR spectra of acylated ureas and thioureas

1987 ◽  
Vol 52 (10) ◽  
pp. 2474-2481 ◽  
Author(s):  
Josef Jirman ◽  
Antonín Lyčka
Keyword(s):  
1H Nmr ◽  
Electron Acceptor ◽  
Sulfur Atom ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
1H Nmr Spectra ◽  
Coupling Constants ◽  
Nmr Chemical Shifts ◽  
H Nmr ◽  
Better Than

A series of 1-acylated and 1,3-diacylated (acyl = acetyl or benzoyl) ureas and thioureas have been prepared and their proton-coupled and proton-decoupled 15N, 13C, and 1H NMR spectra have been measured. All the signals have been assigned. The 15N NMR chemical shifts in 1-acylated ureas and thioureas are shifted downfield as compared with δ(15N) of urea and thiourea, resp. This shift is greater for N-1 than for N-3 nitrogen atoms in both the series. When comparing acylureas and acylthioureas it is obvious from the Δδ(15N) differences that the CS group is better than CO group in transferring the electron-acceptor effect of acyl group. The proton-coupled 15N NMR spectra of the acylureas dissolved in hexadeuteriodimethyl sulphoxide exhibit a doublet of NH group and a triplet of NH2 group at 25 °C. At the same conditions the acylthioureas exhibit a doublet of NH group, the NH2 group signal being split into a doublet of doublets with different coupling constants 1J(15N, H). The greater one of these coupling constants is due to the s-trans proton with respect to the sulfur atom of the thiourea.

A correlation involving 1H NMR spectra and exchange coupling constants of a family of phenoxo-bridged macrocyclic dicopper(ii) complexes

2001 ◽  
Vol 25 (11) ◽  
pp. 1466-1471 ◽  
Author(s):  
Sasankasekhar Mohanta ◽  
Bibhutosh Adhikary ◽  
Sujoy Baitalik ◽  
Kamalaksha Nag
Keyword(s):  
1H Nmr ◽  
Exchange Coupling ◽  
Nmr Spectra ◽  
1H Nmr Spectra ◽  
Coupling Constants

1H NMR spectra of some chloro-alkenes

1981 ◽  
Vol 46 (11) ◽  
pp. 2924-2934
Author(s):  
Seán Cawley ◽  
Jan Schraml ◽  
Petr Svoboda ◽  
Robert Ponec ◽  
Václav Chvalovský
Keyword(s):  
Nmr Spectra ◽  
Chemical Shifts ◽  
Dipole Moments ◽  
Coupling Constants ◽  
The Other ◽  
Dominant Factor ◽  
Proton Proton ◽  
Electric Field Effects ◽  
H Nmr ◽  
Proton Coupling

1H NMR spectra and electric dipole moments of a series of propene derivatives, (CH3)3-nCln.CCH=CH2 (n = 0-3), were measured and the spectra analyzed. Discrepancies in literature data on compounds with n = 0 and 3 are probably due to systematic spectrometer errors. Vinylic proton chemical shifts are found to vary linearly with n in the direction expected on the electronegativity ground (the variations with n occurs in the order HA > HB ≥ HC). Calculations show that even with the extreme reported values of C-C and C-Cl bond magnetic anisotropies, the shift variations with n cannot be accounted for by magnetic anisotropy effects of a freely rotating (CH3)3-nClnC group. Similar calculations rule out electric field effects as the dominant factor. On the other hand, the electron charge distribution, as obtained from CNDO/2 calculations, including d-orbitals and employing Del Bene-Jaffé parametrization, is linearly related to the vinylic proton shifts. This finding supports the earlier interpretation of NMR spectra of vinylsilanes in terms of back-bonding. The vinyl proton-proton coupling constants decrease with increasing n, the changes being larger in the constants which couple proton A (cis) to the other two.

scholarly journals Diagnostically analyzing 1H NMR spectra of sub-types in chaetoglobosins for dereplication

RSC Advances ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 1946-1955 ◽  
Author(s):  
Chen Lin ◽  
Jian-chun Qin ◽  
Yong-gang Zhang ◽  
Gang Ding
Keyword(s):  
Chemical Shift ◽  
1H Nmr ◽  
Nmr Spectra ◽  
Diagnostic Information ◽  
1H Nmr Spectra ◽  
Coupling Constants ◽  
H Nmr

1H-NMR spectra provide abundant diagnostic information including chemical shift values, splitting patterns, coupling constants, and integrals.

Pertrimethylsilylation as a method for improvement of chemical shift additivity through conformational homogenization. 1H and 13C NMR spectra of pertrimethylsilylated derivatives of methyl β-D-xylopyranosides

1983 ◽  
Vol 48 (7) ◽  
pp. 1829-1841 ◽  
Author(s):  
Jan Schraml ◽  
Eva Petráková ◽  
Otomar Pihar ◽  
Ján Hirsch ◽  
Václav Chvalovský
Keyword(s):  
Chemical Shift ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Population Analysis ◽  
Coupling Constants ◽  
Proton Proton ◽  
1H And 13C Nmr ◽  
Proton Coupling ◽  
Derivatives Of ◽  
C Nmr

All possible mono-, di-, and tri- O-methyl, O-benzyl, O-benzoyl, and O-acetyl derivatives of methyl β-D-xylopyranoside were fully trimethylsilylated and their 1H and 13C NMR spectra measured in deuteriochloroform solutions. The spectra were analysed and the chemical shifts completely assigned on the basis of decoupling experiments. The proton-proton coupling constants vary only very little throughout the series. Conformer population analysis by the method of average coupling constants shows that trimethylsilylation increases the C1 conformer population and makes the series conformationally homogenous. Owing to this conformational homogeneity chemical shifts (both 1H and 13C) satisfy very well direct additivity rule. It is suggested that pertrimethylsilylation should be employed whenever deviations from chemical shift additivity are caused by conformational mobility of the investigated series of compounds and when bulky groups can stabilize one of the conformers.

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