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

The reaction of isonicotinic hydrazide with furfural yieldedN′-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...NPy intermolecular hydrogen bond (1) were grown. X-ray diffraction analysis demonstrated that the molecular and crystal structure of1 is identical to that ofN′-thienylideneisonicotinic hydrazide (2). The crystal structure consists of layers. The molecules in the layers are linked in zigzag chains through NH...NPy 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 α-H atom of the furan ring. (In the structure of2, 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.