Geometries and Tautomerism of OHN Hydrogen Bonds in Aprotic Solution Probed by H/D Isotope Effects on 13C NMR Chemical Shifts
| Autor: | Jing Guo, Nikolai S. Golubev, Hans-Heinrich Limbach, Benjamin Koeppe, Peter M. Tolstoy, S. N. Smirnov, Gleb S. Denisov |
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| Rok vydání: | 2010 |
| Předmět: |
Carbon Isotopes
Magnetic Resonance Spectroscopy Nitrogen Isotopes Nitrogen Pyridines Chemistry Hydrogen bond Stereochemistry Chemical shift Temperature Hydrogen Bonding Carbon-13 NMR Deuterium Tautomer Spectral line Oxygen Solutions Crystallography Isomerism Kinetic isotope effect Protons Physical and Theoretical Chemistry Acetic Acid |
| Zdroj: | The Journal of Physical Chemistry A. 114:10775-10782 |
| ISSN: | 1520-5215 1089-5639 |
| DOI: | 10.1021/jp1027146 |
| Popis: | The (1)H and (13)C NMR spectra of 17 OHN hydrogen-bonded complexes formed by CH(3)(13)COOH(D) with 14 substituted pyridines, 2 amines, and N-methylimidazole have been measured in the temperature region between 110 and 150 K using CDF(3)/CDF(2)Cl mixture as solvent. The slow proton and hydrogen bond exchange regime was reached, and the H/D isotope effects on the (13)C chemical shifts of the carboxyl group were measured. In combination with the analysis of the corresponding (1)H 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 (13)C chemical shifts of the carboxyl group with the OHN hydrogen bond geometries. |
| Databáze: | OpenAIRE |
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