Structural studies on aryl-substituted enaminoketones and their thio analogues. Part I. Analysis of high-resolution 1H, 13C NMR and 13C CP MAS spectra combined with GIAO-DFT calculations
✍ Scribed by Marta Bugaj; Piotr A. Baran; Piotr Bernatowicz; Patrycja Brożek; Krystyna Kamieńska-Trela; Adam Krówczyński; Bohdan Kamieński
- Publisher
- John Wiley and Sons
- Year
- 2009
- Tongue
- English
- Weight
- 613 KB
- Volume
- 47
- Category
- Article
- ISSN
- 0749-1581
- DOI
- 10.1002/mrc.2477
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✦ Synopsis
Abstract
A series of aryl‐substituted enaminoketones and their thio analogues in CDCl~3~ solution and in the solid state were studied by the use of high‐resolution ^1^H and ^13^C as well as ^13^C cross polarization magic angle spinning (CP MAS) NMR spectra in combination with gauge including atomic orbitals‐density functional theory (GIAO‐DFT) calculations performed at the B3PW91/6–311 + + G(d,p) level of theory using the B3PW91/6‐311 + + G(d,p)‐optimized geometries. The analysis of the ^13^C NMR spectra in solution was done by using the Incredible Natural Abundance DoublE QUAntum Transfer Experiment (INADEQUATE) technique, whereas trends observed in the ^13^C shielding constants, calculated for the compounds studied, were a great help in assigning most of the signals in the ^13^C CP MAS NMR spectra. It was established on the basis of the experimental and theoretical NMR data that both groups of compounds exist in the form of Z‐s‐Z‐s‐E isomers in CDCl~3~ solution as well as in the solid state, with the N__H__ hydrogen atom involved in intramolecular hydrogen bonding. This conclusion is in agreement with the fact that some of the compounds studied reveal liquid‐crystalline properties. Three‐bond H, H and C, H coupling constants measured in solution played a crucial role in the structure elucidation. Copyright © 2009 John Wiley & Sons, Ltd.