AB INITIO ANALYSIS OF THE STRUCTURE AND INFRARED SPECTRA OF THE FURYLIMIDAZOLES

Abstract

Each of the four isomers (1-, 2-, 4- and 5-) of (2-furyl) imidazole has two stable conformers varying by the mutual orientation of the rings. Ab initio calculations at the $6-31G^{\ast\ast}/MP2$ level show that two of these conformers are nonplanar while the others are completely planar. The degree of nonplanarity is highly sensitive to the level of the calculation, and misleading results can be obtained with smaller basis sets or without correction for electron correlation. Vibrational frequencies have been calculated at the $6-31G^{\ast\ast}$ level, using the $6-31G^{\ast\ast}/MP2$ geometries for the non-planar conformers, and will be scaled using scaling factors derived from furan and imidazole.