Normal coordinate analysis of the enol form of pentane-2,4-dione and its 2H-isotopomers

Abstract

The harmonic and anharmonic vibrational frequencies of the cis-enol form of pentane-2,4-dione (PD) and its 2 H-isotopomers were calculated by density functional theory method (DFT), performed at the B3LYP level. The results of the DFT calculations were subjected to a normal coordinate analysis, giving potential energy distribution (PED) and detailed assignments. Excellent agreement between observed and calculated anharmonic vibrational frequencies was obtained. It is well illustrated that the band frequencies resulted from movements of the enolic ring atoms are considerably coupled with the terminal groups' vibrations.