Vibrational assignment of 4-amino-3-penten-2-one

The infrared and Raman spectra of 4-amino-3-penten-2-one and its two deuterated analogous have been measured. Comparison between the spectra recorded with two techniques, density functional theory (DFT) calculations and the spectral behavior upon deuteration was used for assignment of the vibrational spectra of the titled compound. DFT suggests a relatively strong intramolecular bent hydrogen bond with N⋯O distance in the range of 2.64–2.67 Å, which is in agreement with the observed νNH at 3180 cm −1. Existence of an intermolecular hydrogen bond is also shown in both solid and solution phases. The spectroscopic data support the enamine structure for this compound rather than imine structure.