Doi: 10.1002/mrc.1481

The tautomerism of 1H-pyrazole-3(5)-(N-tert-butyl)carboxamide in the solid state and in solution

The X-ray crystal structure of 1H-pyrazole-3-(N-tert-butyl)-carboxamide was determined. In the solid state, the ¹³C and ¹⁵N CP/MAS NMR spectra correspond to this tautomer. In solution, both tautomers are present in a ratio that depends on the temperature (at 293 K, 90% 3-substituted/10% 5-substituted). Some unusual ¹H, ¹H couplings involving the NH proton were observed. DFT (GIAO) calculations were carried out.