Structural and Vibrational Study of 2-(2’- Furyl)-1H-imidazole

A. E. LEDESMA, S. A. BRANDÁN, J. ZINCZUK, O. E. PIRO, J. J. LÓPEZ GONZÁLEZ, A. BEN ALTABEF

JOURNAL OF PHYSICAL ORGANIC CHEMISTRY

John Wiley & Sons, Ltd.

Lugar: New York; Año: 2008 vol. 21 p. 1086 - 1097

0894-3230

The 2-(2 -furyl)-1H-imidazole (1) has been prepared and characterized using infrared,Raman, and multidimensional nuclear magnetic resonance spectroscopies. Twoconformations of this species obtained by rotation of 180°, approximately, around theC C inter-ring bond are detected. Likewise, the crystal and molecular structure of 1has been analyzed by X-ray diffraction methods and it evidenced that bothconformations are present in the lattice with equal occupancy and linked in alternateway to the N H---N bonded polymeric chains along the crystal [101] direction.Theoretical calculations have been carried out by employing the density functionaltheory (DFT)/B3LYP method, in order to optimize the geometry in gas phase of bothconformers and to support the assignments of the vibrational bands of 1 to theirnormal modes. For a complete assignment of the compound, DFT calculations werecombined with Pulay´s SQMFF methodology in order to fit the theoretical frequencyvalues to the experimental one. The nuclear magnetic resonance spectrum observedfor 1 is successfully compared with the calculated chemicals shifts at B3LYP/6-311++G** level of theory for the two conformers. Furthermore, natural bond orbital(NBO) analysis and topological (AIM) calculations for an oligomer, containing threealternated units of the N H---N bonded chain found in the crystal, reveals thecharacteristics of the hydrogen bonds present in the polymeric structure.