J. Bellanato, F. Florencio, S. G. Blanco
Nov 2, 1987
Citations
0
Influential Citations
9
Citations
Journal
Journal of Molecular Structure
Abstract
Abstract Seven 2-amino-4 H -pyran derivatives have been studied by IR and Raman spectroscopy and the crystal structure of one (2-amino-3,5-dicyano-4-isopropyl-6-methyl-4 H -pyran) has been determined by X-ray diffraction. For the purposes of comparison 3,5-dicyano-2,6-dimethyl-4-phenyl-4 H -pyran has also been studied. The seven 2-amino-4 H -pyran derivatives considered contain an enaminonitrile system in their structure and present similar spectroscopic characteristics. However, the electronic properties of the substituents at the C(5) and C(6) atoms induce frequency and intensity changes in the corresponding ν(CC) IR and Raman band (“γ-pyran” band) and consequently in the degree of coupling with the ν(CC) of the C(2)C(3) bond (enamine band). The spectra reveal differences in the strength of hydrogen bonding and in the “planarity” of the ring. X-ray data for 2-amino-3,5-dicyano-4-isopropyl-6-methyl-4 H -pyran show that the conformation of the pyran ring is a distorted boat. The N⋯NC intermolecular distances also indicate weak intermolecular hydrogen bonds in the crystal between the amino group of each molecule and two cyano groups of two neighbouring molecules.