Dependence of Calculated NMR Proton Chemical Shifts on Electron Density Properties in Proton-Transfer Processes on Short Strong Hydrogen Bonds

2004 ◽  
Vol 108 (52) ◽  
pp. 11783-11792 ◽  
Author(s):  
Luis F. Pacios ◽  
Pedro C. Gómez
Keyword(s):  
Hydrogen Bonds ◽  
Proton Transfer ◽  
Electron Density ◽  
Chemical Shifts ◽  
Transfer Processes ◽  
Proton Chemical Shifts

Carbon-13 and proton chemical shifts of cyclohexanes in relation to interaction energy

1970 ◽  
Vol 48 (16) ◽  
pp. 2639-2643 ◽  
Author(s):  
A. S. Perlin ◽  
H. J. Koch
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Interaction Energy ◽  
Electron Density ◽  
Chemical Shifts ◽  
Nuclear Magnetic Resonance Spectra ◽  
Proton Chemical Shifts ◽  
Magnetic Resonance Spectra ◽  
Nuclear Magnetic

A comparison of nuclear magnetic resonance spectra for isomeric cyclohexane derivatives (methyl, hydroxyl, halogen) shows that net shielding of carbon-13 nuclei of these compounds increases additively with an increase in repulsive non-bonding interactions, and thus with decreasing enthalpy in the series. By contrast, an inverse shielding pattern is found for the appended protons. Hence, a destabilizing interaction in these compounds alters polarization of the C—H bond, placing greater electron density on carbon, and its impact appears to be delocalized over many C—H bonds of the molecule.

The electron attachment effect on the structure and properties of orto-hydroxyaryl Schiff and Mannich bases – hydrogen/proton transfer processes

2021 ◽  
Author(s):  
Jerzy Jański ◽  
Szczepan Roszak ◽  
Kazimierz Wladyslaw Orzechowski ◽  
Lucjan Sobczyk
Keyword(s):  
Hydrogen Bonds ◽  
Proton Transfer ◽  
Electron Attachment ◽  
Mannich Bases ◽  
Biological Processes ◽  
Structure And Properties ◽  
Intramolecular Hydrogen Bonds ◽  
Transfer Processes ◽  
Intramolecular Hydrogen

The attachment of electrons is known to significantly influence some chemical and biological processes. The chemical differences between Schiff and Mannich bases characterized by strong intramolecular hydrogen bonds, result from...

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