Table 1.
19F NMR shifts (experimental and calculated) and fluorine electrostatic potential (charge) for stable tautomers of 2-fluoro- and 4-fluoro-imidazole analogues.
| 2F isomers, τ-tautomers | 2F-His | 2F-MeIm | 2F-Im |
|---|---|---|---|
| ESP charge | -0.264 | -0.278 | -0.280 |
| 19F NMR shifts (calculated) | 54.96 | 53.62 | 52.50 |
| 19F NMR shifts (experimental) | 59.80 | 58.59 | 56.60 |
| 4F isomers, π-tautomers | 4F-His | 4F-MeIm | 4F-Im |
| ESP charge | -0.290 | -0.275 | -0.308 |
| 19F NMR shifts (calculated) | 16.54 | 13.83 | 21.97 |
| 19F NMR shifts (experimental) | 20.25 | 16.91 | 23.43 |