The stereochemistry of organometallic compounds. XIV. trans-Effects in the 13C N.M.R. spectra of Dicarbonyltriphenyl-phosphine- and -arsine-(arene)chromium compounds

1976 ◽  
Vol 29 (11) ◽  
pp. 2431 ◽  
Author(s):  
WR Jackson ◽  
CF Pincombe ◽  
ID Rae ◽  
D Rash ◽  
B Wilkinson
Keyword(s):  
Chemical Shifts ◽  
Organometallic Compounds ◽  
Triphenyl Phosphine ◽  
13C Chemical Shifts ◽  
Chromium Compounds ◽  
Group 5 ◽  
Deshielding Effect

The 13C chemical shifts of some triphenyl-phosphine and -arsine dicarbonyl(arene)chromiums are reported. The shifts are discussed in terms of a deshielding effect on the arene ring carbons trans to the Group 5 atom in the preferred conformations of these molecules.

Substituent effects on the 13C chemical shifts of monosubstituted twistanes

1977 ◽  
Vol 55 (17) ◽  
pp. 3161-3165 ◽  
Author(s):  
Helmut Beierbeck ◽  
John K. Saunders
Keyword(s):  
Chemical Shift ◽  
Substituent Effect ◽  
Chemical Shifts ◽  
Substituent Effects ◽  
13C Chemical Shifts ◽  
Bond Interaction ◽  
Chemical Shift Data ◽  
Shift Data ◽  
Deshielding Effect

The 13C chemical shift data for some hydroxy, chloro, bromo, and oxo twistane derivatives are presented and compared to the shifts observed in corresponding adamantanes. The substituent effect at the α and β carbons is more pronounced in twistanes than in adamantanes. The substituent shift induced at an antiperiplanar γ carbon is shown to depend on the presence or absence of 1,3-diaxial hydrogen–hydrogen interactions between the substituted and γ carbons. If such an interaction is present the effect is of shielding whereas if it is absent, the effect is of deshielding. The deshielding effect appears to occur via a through bond interaction.

The High Resolution NMR Spectra of Pesticides. II. The DDT-Type Compounds

1969 ◽  
Vol 52 (5) ◽  
pp. 1074-1092 ◽  
Author(s):  
L H Keith ◽  
A L Alford ◽  
A W Garrison
Keyword(s):  
Nuclear Magnetic Resonance ◽  
High Resolution ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
Aromatic Rings ◽  
Nuclear Magnetic Resonance Spectra ◽  
High Resolution Nmr ◽  
Related Compounds ◽  
Deshielding Effect

Abstract The high resolution nuclear magnetic resonance spectra of the DDT class of pesticides and related compounds are discussed, including a study of the resonances of the aromatic protons as they are affected by various substiluents. The CCl3 moiety on the α-carbon strongly deshields the ortho protons on the aromatic rings, and this deshielding effect is greatly enhanced by substitution of a chlorine ortho rather than para on the aromatic ring. These deshielding effects are explained by a consideration of the electronegativity of the substituents and the stereochemistry of the molecule. The chemical shifts and coupling constants are tabulated.

scholarly journals Real-time prediction of 1H and 13C chemical shifts with DFT accuracy using a 3D graph neural network

2021 ◽  
Author(s):  
Yanfei Guan ◽  
S. V. Shree Sowndarya ◽  
Liliana C. Gallegos ◽  
Peter C. St. John ◽  
Robert S. Paton
Keyword(s):  
Neural Network ◽  
Real Time ◽  
Quantum Chemical ◽  
Organic Molecules ◽  
Chemical Shifts ◽  
13C Chemical Shifts ◽  
Time Prediction ◽  
Nmr Data ◽  
Proton Chemical Shifts

From quantum chemical and experimental NMR data, a 3D graph neural network, CASCADE, has been developed to predict carbon and proton chemical shifts. Stereoisomers and conformers of organic molecules can be correctly distinguished.

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