High-resolution solid-state carbon-13 nuclear magnetic resonance spectra of mofebutazone, phenylbutazone, and oxyphenbutazone in relation to X-ray crystallographic data.

The solid-state 13C NMR spectra of mofebutazone, phenylbutazone, and oxyphenbutazone monohydrate and anhydrate are presented. The crystal structures of these pyrazolidinedione derivatives, obtained by single-crystal X-ray analysis, were previously reported, revealing distinct differences in crystal structure. In this report, the chemical shift values observed for the solid-state 13C spectra are related to the chemical environment of the various carbon atoms and compared with the crystallographic data. Results indicate that solid-state NMR spectroscopy is potentially useful in the study of drugs in the solid state.