학술논문
Geometries and Tautomerism of OHN Hydrogen Bonds in Aprotic Solution Probed by H/D Isotope Effects on 13C NMR Chemical Shifts.
Document Type
Article
Author
Source
Subject
*TAUTOMERISM
*HYDROGEN bonding
*SOLUTION (Chemistry)
*HYDROGEN isotopes
*NUCLEAR magnetic resonance spectroscopy
*TEMPERATURE effect
*FINITE geometries
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Language
ISSN
1089-5639
Abstract
The 1H and 13C NMR spectra of 17 OHN hydrogen-bonded complexes formed by CH313COOH(D) with 14 substituted pyridines, 2 amines, and N-methylimidazole have been measured in the temperature region between 110 and 150 K using CDF3/CDF2Cl mixture as solvent. The slow proton and hydrogen bond exchange regime was reached, and the H/D isotope effects on the 13C chemical shifts of the carboxyl group were measured. In combination with the analysis of the corresponding 1H chemical shifts, it was possible to distinguish between OHN hydrogen bonds exhibiting a single proton position and those exhibiting a fast proton tautomerism between molecular and zwitterionic forms. Using H-bond correlations, we relate the H/D isotope effects on the 13C chemical shifts of the carboxyl group with the OHN hydrogen bond geometries. [ABSTRACT FROM AUTHOR]