15N NMR chemical shifts of NH‐pyrazoles in the solid state and in solution at low temperature

The 15N chemical shifts of thirteen NH‐pyrazoles in the solid state and of seven NH‐pyrazoles in [2H8] THF solution at 170–175 K (with frozen annular tautomerism) are reported. The solid‐state values are discussed using an additive model. The differences in chemical shifts between the solid state and solution are due to the different intermolecular hydrogen bonds present in the various environments.