Ab Initio ¹³C NMR and Structural Studies of the (Trifluoromethyl)cyclopentyl Carbocations
Ab initio calculations at the MP2/cc-pVTZ level of theory show that the classical 1-(trifluoromethyl)cyclopentyl cation (11) is substantially destabilized (by 9.8 kcal/mol) as compared to its isomeric µ-hydrido-bridged global minimum structure 16. However, the classical carbocation 11 is relatively more stable than the nonclassical cyclobutylmethyl cations 6 and 7, by 7.9 and 3.6 kcal/mol, respectively. We have also shown involvement of the noncovalent H···F bonding interactions in the µ-hydrido bridged structures, 13, 16, 19, and 20. The latter H···F bond distances are dependent on the number of fluorines in the fluoroalkyl group, and decrease in the order: 16 (CF3) > 20 (CHF2) > 19 (CH2F), in accordance with the decreased basicity of the fluorine atom across this series.
P. Reddy et al., "Ab Initio ¹³C NMR and Structural Studies of the (Trifluoromethyl)cyclopentyl Carbocations," Journal of Fluorine Chemistry, vol. 210, pp. 83-87, Elsevier B.V., Jun 2018.
The definitive version is available at https://doi.org/10.1016/j.jfluchem.2018.03.001
Keywords and Phrases
13C NMR; Ab initio; Carbocations; GIAO-MP2; Hydrogen bonding; Trifluoromethyl; Î¼-hydrido bridged
International Standard Serial Number (ISSN)
Article - Journal
© 2018 Elsevier B.V., All rights reserved.
01 Jun 2018