ИСТИНА

Hexafluoroacetone (HFA) is a compound that widely used in organic synthesis, chemistry of heat resistant polymers and biochemistry. The vibrational spectra of HFA have been previously studied [1]. However, absolute IR intensities of HFA were not measured, and an ab initio prediction of its anharmonic IR intensities was not performed either. We re-measured gasphase infrared spectra of HFA with a resolution of 1 cm−1 in the range of 2000–340 cm−1. For the first time, experimental absolute IR intensities of bands were determined. Theoretical ab initio molecular structures, semi-diagonal quartic potential energy surfaces (PES), and cubic surfaces of dipole moments (DM) components of the HFA were calculated by the second-order Møller-Plesset electronic perturbation theory (MP2) with a correlation consistent Dunning triple-ζ basis set (cc-pVTZ). The numerical-analytic implementation of the second-order operator canonical Van Vleck perturbation theory (CVPT2) was employed for predicting anharmonic IR spectra of HFA. Double canonical transformations of DM expansions were used for prediction of integral intensities of fundamental transitions in IR spectra. The main result is presented in Fig. 1. A good agreement between observed and predicted IR intensities is observed. A thorough interpretation of the IR experimental spectra and existing literature data for HFA is accomplished, and a number of assignments reconsidered.