X-ray and IR spectroscopic studies of specific intermolecular interactions in N'-substituted isonicotinohydrazides

N'-Thenylidene- and N'-(o-nitrobenzylidene)hydrazides of isonicotinic acid have been studied by X-ray structural analysis and IR spectroscopy. In the crystalline state, these molecules are linked through intermolecular N-H ... N-Py hydrogen bonds. Carbonyl groups are not involved in intermolecular hydrogen bonds. However, it was found that the C=O group participates in an attractive interaction with the sulfur atom of the thiophene group. The energy of this interaction is comparable with the energies of intermolecular C=O ... H-N hydrogen bonds in amides.