Article ID Journal Published Year Pages File Type
1238124 Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 2008 10 Pages PDF
Abstract
The conformational stability of 2,2,3,3,3-pentafluoro-1-propanol was investigated by the DFT-B3LYP/6-311+G** and the ab initio MP2/6-311+G** calculations. The calculated potential energy curves of 2,2,3,3,3-pentafluoro-1-propanol at both levels of theory were consistent with three distinct minima that correspond to Trans-gauche-gauche (Tgg), trans-trans-gauche (Ttg) and trans-gauche-gauche(−) (Tgg1) conformers in the order of decreasing relative stability. The equilibrium constants for the conformational interconversion of 2,2,3,3,3-pentafluoro-1-propanol were calculated and found to correspond to an equilibrium mixture of about 46% Tgg, 43% Ttg and 11% Tgg1 conformations at 298.15 K. The calculated (%Ttg/%Tgg) ratio of 0.93 is consistent with the 0.85 ratio of the observed intensities of the 772 and 794 cm−1 lines in the Raman spectrum of the liquid. The nature of the high energy Ttg conformation was verified by solvent experiments using formamide (ɛ = 109.5) and acetonitrile (ɛ = 37). The vibrational frequencies of the molecule in its stable forms were computed at B3LYP level and complete vibrational assignments were made based on normal coordinate calculations and comparison with experimental data of the molecule.
Related Topics
Physical Sciences and Engineering Chemistry Analytical Chemistry
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