Crystal structures and IR, NMR and UV spectra of 4-formyl- and 4-acetylpyridine N(4)-methyl- and N(4)-ethylthiosemicarbazones

4-Formyl- and I-acetylpyridine N(4)-methyl- and N(4)-ethylthiosemicarbazone have been prepared, their structures solved and IR, NMR and UV spectra recorded. Intramolecular and intermolecular hydrogen bonding are both present, but the mode of the intermolecular interaction differs in the four compounds. Further, there is a significant difference in their angles between the mean planes of the pyridine ring and thiosemicarbazone moiety. The H-1 NMR spectral studies show significant differences between the compounds as do UV and IR spectra. (C) 2001 Elsevier Science B.V. All rights reserved.