## Abstract The 251 MHz ^1^H and the natural‐abundance 63.1 MHz ^13^C NMR spectra of __N__,__N__'‐dimethylimidazolidine have been measured from −50 to −170°C. Below about −140°C. nitrogen inversion in the compound becomes slow on the NMR time scale and both the ^1^H and the ^13^C spectra indicate t
Magnetization transfer NMR study of nitrogen inversion in 2,2-dimethylaziridine
✍ Scribed by Eric R. Johnston
- Publisher
- John Wiley and Sons
- Year
- 1995
- Tongue
- English
- Weight
- 411 KB
- Volume
- 33
- Category
- Article
- ISSN
- 0749-1581
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✦ Synopsis
Abstract
The slow inversion at pyramidal nitrogen in 2,2‐dimethylaziridine was investigated by NMR spectroscopy at 304 K using one‐dimensional spin locking methods and two‐dimensional exchange spectroscopy. The activation free energy was found to be 17.5 kcal mol^−1^ (73.2 kJ mol^−1^) at this temperature. This value represents a lower limit for the unimolecular inversion barrier height as autocatalytic and water‐catalyzed inversion pathways can in principle also contribute to the observed rate. The spin locking experiments described employ non‐selective pulses and are particularly useful for the quantitative study of slow chemical exchange between nuclei of similar resonance frequency where selective magnetization transfer experiments are difficult or impossible.
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