Correlation of the chemical shifts with ?-electron densities in mono-derivatives of benzene, pyridine, and pyrazine

1968 ◽  
Vol 17 (5) ◽  
pp. 951-958
Author(s):  
G. G. Dvoryantseva ◽  
V. P. Lezina ◽  
V. F. Bystrov ◽  
T. N. Ul'yanova ◽  
G. P. Syrova ◽  
...  
Keyword(s):  
Chemical Shifts ◽  
Electron Densities ◽  
Derivatives Of

Proton chemical shifts and electron densities in aromatic and heteroaromatic molecules. II. Derivatives of pyrrole and furan

1967 ◽  
Vol 20 (7) ◽  
pp. 1325 ◽  
Author(s):  
PJ Black ◽  
RD Brown ◽  
ML Heffernan
Keyword(s):  
Electron Distribution ◽  
Chemical Shifts ◽  
Membered Ring ◽  
Electron Densities ◽  
Heteroaromatic Compounds ◽  
Derivatives Of ◽  
Proton Chemical Shifts

In this paper, the methods outlined in Part I are used to estimate the electron distribution from the proton chemical shifts in a series of five-membered ring heteroaromatic compounds. The systems studied are pyrrole and furan, their benzo and dibenzo derivatives, indazole, indolizine, the azaindolizines, and purine. It is found that the estimated excess charges are not as closely represented by the BJ VESCF method as was the case for the azine derivatives and that the role of the σ-electrons is in urgent need of closer investigation.

Solvent effects on the chemical shifts of halogenated derivatives of diphenyl sulphone, dibenzothiophene and dibenzothiophene 5,5-dioxide

1990 ◽  
pp. 2071-2074 ◽  
Author(s):  
Angela R. Suárez ◽  
Margarita C. Briñón ◽  
María M. de Bertorello ◽  
Manuel González Sierra ◽  
Pedro Joseph-Nathan
Keyword(s):  
Solvent Effects ◽  
Chemical Shifts ◽  
Derivatives Of

29Si-Kernresonanzuntersuchungen an N-Trimethylsilyl-substituierten Aminen und Amiden / 29Si Nuclear Magnetic Resonance Studies on N-Trimethylsilyl Derivatives of Amines and Amides

1977 ◽  
Vol 32 (2) ◽  
pp. 163-166 ◽  
Author(s):  
B. Heinz ◽  
H. C. Marsmann ◽  
U. Niemann
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Aromatic Amines ◽  
Chemical Shifts ◽  
Substituent Effects ◽  
Electronic Charge ◽  
Magnetic Resonance Studies ◽  
Basic Character ◽  
Silyl Derivatives ◽  
Trimethylsilyl Derivatives ◽  
Derivatives Of

The 29Si chemical shifts of several trimethyl silyl derivatives of amines and amides are measured and compared to other chemical and theoretical properties such as the basicities or the electronic charge on the nitrogen or the hydrogen of the N-H group of the amine or the amide. Whereas the 29Si chemical shift of saturated amines can be rationalized in terms of substituent effects, the shifts of aromatic amines show some dependency on the basic character of the amine. There seems to be little correlation between 29Si chemical shifts and electronic charge, but there is a similarity of 29Si with 1H chemical shifts of the NH group, which is interpreted as depending on anisotropy effects.

ChemInform Abstract: (19)F NMR CHEMICAL SHIFTS IN FLUOROPHENYL DERIVATIVES OF SILICON-PLATINUM COMPLEXES

1974 ◽  
Vol 5 (13) ◽  
pp. no-no
Author(s):  
C. EABORN ◽  
M. R. HARRISON ◽  
P. N. KAPOOR ◽  
D. R. M. WALTON
Keyword(s):  
Chemical Shifts ◽  
Platinum Complexes ◽  
Nmr Chemical Shifts ◽  
Derivatives Of ◽  
19 F Nmr

N.M.R. spectra and stereochemistry of the bipyridyls. III. 2,2'-Bipyridyl and dimethyl derivatives, 3,3'- bipyridyl, and 4,4' - bipyridyl

1967 ◽  
Vol 20 (6) ◽  
pp. 1227 ◽  
Author(s):  
TM Spotswood ◽  
CI Tanzer
Keyword(s):  
Hydrogen Bonding ◽  
Electrostatic Field ◽  
Field Effect ◽  
Chemical Shifts ◽  
Lone Pair ◽  
Diamagnetic Anisotropy ◽  
Equal Importance ◽  
Nitrogen Lone Pair ◽  
Lone Pair Electrons ◽  
Derivatives Of

The analysis of the n.m.r, spectra of 2,2?-, 3,3?-, and 4,4?-bipyridyl and three dimethyl-2,2?-bipyridyls is reported and the factors determining the relative chemical shifts of the ring protons and methyl groups in several solvents are discussed. The diamagnetic anisotropy of the neighbouring ring and electrostatic field effect of the nitrogen lone pair electrons are shown to be of roughly equal importance for derivatives of 2,2?-bipyridyl except in hydrogen bonding solvents. Attenuation of the electrostatic field effect in polar, and particularly in hydrogen bonding solvents, is established for 4- picoline, and for the bipyridyls, and this effect is responsible for striking changes in the spectrum of 2,2?-bipyridyl in hydrogen bonding solvents. An approximate interplanar angle of 58� is derived for 3,3?- dimethyl-2,2?-bipyridyl, and 2,2?-bipyridyl and its 4,4?- and 5,5?- dimethyl derivatives appear to be trans coplanar in all solvents. 3,3?- Bipyridyl and 4,4?-bipyridyl are probably highly twisted in all solvents, or alternatively, behave as essentially free rotors. The predicted conformations are in good agreement with the electronic spectral data.

Elektronendichte und chemische Verschiebung der Styryldiazin- und Diazaphenanthrenprotonen / Electrondensity and Proton Chemical Shift of Styryldiazines and Diazaphenanthrenes

1972 ◽  
Vol 27 (2) ◽  
pp. 310-319
Author(s):  
H.-H. Perkampus ◽  
Th. Bluhm ◽  
J. Knop
Keyword(s):  
Ring Current ◽  
Chemical Shifts ◽  
Lone Pair ◽  
Current Effect ◽  
Electron Densities ◽  
Paramagnetic Effect ◽  
Nitrogen Lone Pair ◽  
Chemische Verschiebung ◽  
Lone Pair Electrons ◽  
Proton Chemical Shifts

AbstractProton chemical shifts in styryldiazines and diazaphenanthrenes linearly correlate with SCF-π-electron densities of the attached carbon atom and with the electron densities of the hydrogen atom (calculated by the CNDO/2 method). The observed deviations from linearity are discussed in terms of ring current effect, steric effects and the paramagnetic effect of the nitrogen lone pair electrons. An appreciable weakening of ring current is found for diazaphenanthrenes with two adjacent N-atoms. Under the same condition the paramagnetic effect on ortho-hydrogens is increased.

Calcul des déplacements chimiques par la méthode des perturbations finies au niveau INDO avec GIAO et approximation de London. I. 13C et 1H

1982 ◽  
Vol 60 (8) ◽  
pp. 957-969 ◽  
Author(s):  
E. Vauthier ◽  
S. Odiot ◽  
F. Tonnard
Keyword(s):  
Perturbation Method ◽  
Chemical Shifts ◽  
Average Precision ◽  
Electron Densities ◽  
Screening Constant ◽  
First Order ◽  
Finite Perturbation

A formalism for the calculation of σ in the finite perturbation method is developed by keeping hermitian the first order perturbed matrix in B. The σ formalism is separated into mono, di, and triatomic terms, and the importance of the electron densities of neighboring and remote bonds is shown. 13C chemical shifts depend only slightly on the remote bonds in contrast to those for 1H. A calculation of the screening constant for a series of 16 sp and sp2 carbons gives an average precision of 5 ppm for the 13C nuclei. [Journal Translation]

15N NMR study of amino-imino tautomerism in derivatives of 1,4-bis(substituted amino)-9,10-anthraquinones and 1,4-bis(substituted amino)-2,3-dihydro-9,10-anthraquinones

1987 ◽  
Vol 52 (3) ◽  
pp. 736-741 ◽  
Author(s):  
Antonín Lyčka ◽  
Libuše Havlíčková ◽  
Alois Koloničný ◽  
Josef Jirman
Keyword(s):  
Chemical Shifts ◽  
Coupling Constants ◽  
15N Nmr ◽  
Nmr Study ◽  
Derivatives Of ◽  
Tautomeric Mixture

The 15N chemical shifts and 1J(15N, H) coupling constants of 1,4-bis(substituted amino)-9,10-anthraquinones and 1,4-bis(substituted amino)-2,3-dihydro-9,10-anthraquinones indicate that these derivatives exist as true aminoderivatives except for 1,4-bis(phenylamino)-2,3-dihydro-9,10-anthraquinone which forms a tautomeric mixture of the amino and imino forms in deuteriochloroform and hexadeuteriodimethyl sulphoxide.

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