Title

Ab Initio ¹³C NMR and Structural Studies of the (Trifluoromethyl)cyclopentyl Carbocations

Abstract

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.

Department(s)

Chemistry

Comments

Dedicated to the memory of Professor George A. Olah.

Keywords and Phrases

13C NMR; Ab initio; Carbocations; GIAO-MP2; Hydrogen bonding; Trifluoromethyl; μ-hydrido bridged

International Standard Serial Number (ISSN)

0022-1139

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2018 Elsevier B.V., All rights reserved.

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