Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5406937 | Journal of Magnetic Resonance | 2009 | 8 Pages |
Abstract
Using quantum chemistry methods we have evaluated the solvent effects on the 14N NMR chemical shifts in five oxa- and oxadiazoles dissolved in twelve solvents. These solvents differ in their polarity with the dielectric constants varying from 2 to 80. Moreover, three of them have a hydrogen-bond donor character. All possible hydrogen-bonding in the water solution with the oxygen and nitrogen (hydrogen-acceptor) centers in oxazoles (2) and oxadiazoles (3) have been considered in our studies. It has been shown that both the pure solvent and hydrogen-bonding effects are significant and result in 14N magnetic shielding increase. In water solutions the pure solvent effect is larger than the hydrogen-bonding effect. In addition, the solvent effect has been analyzed in terms of its direct and indirect contributions. It should be emphasized that our theoretical results for 14N chemical shifts in oxa- and oxadiazoles remain in a very good agreement with the accurate experimental data.
Keywords
Related Topics
Physical Sciences and Engineering
Chemistry
Physical and Theoretical Chemistry
Authors
Agnieszka Ksiazek, Piotr Borowski, Krzysztof Wolinski,