Investigations on the hydrogen bond interaction in the aniline-furan complex and its cation by infrared depletion spectroscopy

The vibrational spectra of the NH2 stretching modes of the aniline-furan complex and its cation in a supersonic jet have been measured by infrared depletion spectroscopic methods. Two absorption bands have been observed at 3409 and 3497 cm(-1) in the spectrum of the neutral aniline-furan complex, which is red-shifted from the corresponding bands of aniline monomer by 12 and 11 cm(-1), respectively. The main intermolecular interaction of the complex has been found to be a weak hydrogen bond between the NH bond of aniline and the lone pair of the oxygen atom of furan. As for the aniline-furan cation complex, two strong absorption bands have been observed at 3315 and 3446 cm(-1) in the infrared spectrum. In this case, the main intermolecular interaction has been found to be the NH-pi type hydrogen bond between one of the NH bonds and the pi-electron of the aromatic ring of furan. The difference between the interactions of the neutral and the cation complexes has been discussed.