scholarly journals Understanding 125Te NMR chemical shifts in disymmetric organo-telluride compounds from natural chemical shift analysis

2020 ◽  
Vol 22 (4) ◽  
pp. 2319-2326 ◽  
Author(s):  
Ewa Pietrasiak ◽  
Christopher P. Gordon ◽  
Christophe Copéret ◽  
Antonio Togni
Keyword(s):  
Chemical Shift ◽  
Chemical Shifts ◽  
Lone Pair ◽  
Magnetic Coupling ◽  
Nmr Chemical Shifts ◽  
Shift Analysis ◽  
Theoretical Investigations ◽  
Chemical Shift Analysis

Magnetic coupling of the lone pair: theoretical investigations reveal the origin of 125Te chemical shift in disymmetric organotellurides

Chemical-shift analysis of O Kα by EPMA color-mapping method for BiSrCaCuO superconductive specimen

1992 ◽  
Vol 50 (1) ◽  
pp. 82-83
Author(s):  
H. Takahashi ◽  
T. Okumura ◽  
Y. Seo ◽  
A. Kabaya ◽  
C. Nielsen
Keyword(s):  
Chemical Shift ◽  
Crystal Structures ◽  
Chemical Shifts ◽  
Mapping Method ◽  
Color Mapping ◽  
Shift Analysis ◽  
Spectral Peaks ◽  
Sintering Method ◽  
Chemical Shift Analysis ◽  
Acid Phthalate

The chemical shifts of x-ray spectra are now frequently observed with EPMA (Electron Probe Microanalysis). The conventional method of chemical-shift analysis with EPMA is to compare the peak shapes and peak positions of standard spectra with those of unknown spectra. We reported that O-Kα peak shapes detected by using a TAP (Thallium acid phthalate) crystal reflect their crystal structures. Fig. 1 shows these O-Kα spectral peaks. In the present study, concerning the BiSrCaCuO superconductor made by the sintering method, it was observed that the O-Kα spectra of several kinds of phases reflected their crystal structures. Moreover, it is now possible to observe these chemical shifts of spectra by using the color mapping method in EPMA.

Origin of the 29Si NMR chemical shift in R3Si–X and relationship to the formation of silylium (R3Si+) ions

2020 ◽  
Vol 49 (45) ◽  
pp. 16453-16463 ◽  
Author(s):  
Winn Huynh ◽  
Matthew P. Conley
Keyword(s):  
Chemical Shift ◽  
Chemical Shifts ◽  
29Si Nmr ◽  
Surface Oxygen ◽  
Nmr Chemical Shift ◽  
Dft Methods ◽  
Nmr Chemical Shifts

The origin in deshielding of 29Si NMR chemical shifts in R3Si–X, where X = H, OMe, Cl, OTf, [CH6B11X6], toluene, and OX (OX = surface oxygen), as well as iPr3Si+ and Mes3Si+ were studied using DFT methods.

Carbon-13 chemical shifts of alkene carbons in 2-acylidene-3,5-diaryl-2,3-dihydro-1,3,4-thiadiazoles and related benzothiazoles and -selenazoles, and their relationship to other push-pull alkenes

1996 ◽  
Vol 74 (7) ◽  
pp. 1329-1334 ◽  
Author(s):  
Jennifer L. Mueller ◽  
Martin S. Gibson ◽  
J. Stephen Hartman
Keyword(s):  
Chemical Shift ◽  
Key Words ◽  
Chemical Shifts ◽  
Charge Delocalization ◽  
Nmr Chemical Shifts ◽  
Charge Polarization

Carbon-13 chemical shifts of alkene carbons are observed in the ranges 78–109 ppm (Cα) and 154–164 ppm (Cβ) for a series of 11 2-acylidene-3,5-diaryl-2,3-dihydro-1,3,4-thiadiazoles, 3 2-acylidene-3-alkyl-2,3-dihydrobenzothiazoles, and 2 2-acylidene-3-alkyl-2,3-dihydrobenzoselenazoles of known geometry, indicating appreciable charge polarization in these compounds as in other push–pull olefins. Substitution that promotes more extensive charge delocalization results in the Cα signal shifting to the higher-frequency end of the chemical shift range. The observed shifts are compared with those calculated according to the Pretsch scheme. Key words: carbon-13 NMR, chemical shifts, push–pull olefins, 1,3,4-thiadiazoles, benzothiazoles, benzoselenazoles.

Probing structural patterns of ion association and solvation in mixtures of imidazolium ionic liquids with acetonitrile by means of relative1H and13C NMR chemical shifts

2015 ◽  
Vol 17 (35) ◽  
pp. 23183-23194 ◽  
Author(s):  
Bogdan A. Marekha ◽  
Oleg N. Kalugin ◽  
Marc Bria ◽  
Abdenacer Idrissi
Keyword(s):  
Ionic Liquids ◽  
Chemical Shift ◽  
Chemical Shifts ◽  
Ion Association ◽  
Ion Solvation ◽  
Mixture Composition ◽  
Imidazolium Ionic Liquids ◽  
Structural Patterns ◽  
Nmr Chemical Shifts ◽  
Molecular Solvents

Competition between ion solvation and association in mixtures of imidazolium ionic liquids and molecular solvents can be systematically addressed by the analysis of relative chemical shift variation with mixture composition.

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