Intra- and intermolecular interactions in crystals of N′-furfurylideneisonicotinic hydrazide and related compounds.: IR spectroscopic and X-ray diffraction studies

The reaction of isonicotinic hydrazide with furfural yielded N'-furfurylideneisonicotinic hydrazide. IR spectroscopic studies demonstrated that crystallization from different solvents afforded products with an intermolecular NH...O=C hydrogen bond. Conditions of crystallization were chosen under which single crystals with the NH N-Py intermolecular hydrogen bond (1) were grown. X-ray diffraction analysis demonstrated that the molecular and crystal structure of 1 is identical to that of N'-thienylideneisonicotinic hydrazide (2). The crystal structure consists of layers. The molecules in the layers are linked in zigzag chains through NH...N-Py intermolecular hydrogen bonds. The molecules of the adjacent chains (in the layer) are linked through C=O...H-C intermolecular hydrogen bonds between the O atom of the carbonyl group and the alpha-H atom of the furan ring. (In the structure of 2, the chains are linked through specific intermolecular interactions of different nature but with approximately identical energy.) The replacement of the thiophene fragment (2) by the furan ring (1) is accompanied by a change in the intramolecular electronic effects, which is reflected both in the geometric and spectral characteristics of the molecules in the crystal.