Partially Fluorinated Butatrienes: A Coupled Cluster Study

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• 作者：Christian Ehm ; Dieter Lentz
• 刊名：Journal of Physical Chemistry A
• 出版年：2010
• 出版时间：March 18, 2010
• 年：2010
• 卷：114
• 期：10
• 页码：3609-3614
• 全文大小：263K
• 年卷期：v.114,no.10(March 18, 2010)
• ISSN：1520-5215

文摘

The geometries of 19 different partially fluorinated butatrienes and their related butenyne isomers have been calculated at the Møller−Plesset second order perturbation theory level with Dunning’s valence triple-ζ basis set. Final energies were determined at the CCSD(T)/cc-pVQZ level of theory. Increasing fluorine substitution has only a limited effect on the bond lengths but a substantial effect on the angles. The CCC bond angles of 4 of the 5 partially fluorinated butatrienes show a deviation of more than 2° from collinearity, therefore representing angle-strained butatrienes. Increasing degree of fluorination has a substantial effect on the isomerization energies. The energy difference between the least stable enyne nonfluorinated at the acetylenic center and the most stable enyne fluorinated at the acetylenic center decreases from 66.8 kJ/mol, in case of the monofluorinated system, to 29.7 kJ/mol in the triple fluorinated system. The acetylenic F substitution is crucial in raising the energies of fluorinated but-1-en-3-yne relative to their butatriene isomers. Within the triple fluorinated system and unprecedented for all discussed molecules, 1,1,4-trifluoro-but-1-en-3-yne represents the only molecule fluorinated at the acetylenic center that is more stable than its triene isomer.