Infrared vibrational spectra and absolute intensities of fundamental bands of bis(trifluoromethyl)ketene: ab initio interpretation using the second order operator Van Vleck perturbation theoryстатьяИсследовательская статья
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Дата последнего поиска статьи во внешних источниках: 3 ноября 2021 г.
Аннотация:Bis(triuoromethyl)ketene (BTFMK, (CF3)2C=C=O) is an important chemical compound for the organic synthesis and in polymer chemistry. In this work, IR spectra of gaseous BTFMK were recorded in the range of 2280–400 cm-1 with a resolution of 1 cm-1. The experimental absolute IR intensities of 17 fundamental bands of BTFMK were measured and juxtaposed with ab initio anharmonic ones. The molecular structures, semi-diagonal quartic potential energy surfaces (PES), and cubic surfaces of dipole moment components (^μα) were calculated at the MP2/cc-pVTZ level of theory. The predicted frequencies were refined by substituting the harmonic part of PES with the MP2/cc-pVQZ counterparts. The second-order operator canonical Van Vleck perturbation theory (CVPT2) was employed for predicting anharmonic energy levels, IR integral intensities and full experimental (re)-assignments. The deviation of predicted IR intensities from observations for ν1-ν4, ν6, ν7, ν9, ν14, ν15, ν22 was ≤12% on average. Three predicted Fermi resonances were experimentally identified: ν14/ν6+ν20, ν17/ν9+ν21 and ν18/ν7+ν25.