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Rearrangement of Perfluorocyclobutyne

Published

Author(s)

K B. Wiberg, M Marquez, Carlos A. Gonzalez

Abstract

The energies of cyclobutyne, perfluorocyclobutyne and related compounds have been calculated at levels from MP2/6-31G* through QCISD(T)/6-311+G*, and also at B3LYP and B3PW91/6-311+G*. The relative energies found with the larger basis sets are quite consistent. Cyclobutyne is calculated to be a transition state at most levels of theory, leading to cyclopropylidenecarbene. However, the latter does not have C^2^v symmetry, but rather undergoes a tilt of the carbene carbon toward a ring carbon leading to a distorted C^s structure. Perfluorocyclobutyne is calculated to have a significant activation energy for rearrangement at the MP2 level, but higher levels of theory suggest that it will rearrange spontaneously to perfluorocyclopropylidenecarbene, again with a distorted structure. The calculated heats of hydrogenation of the cyclobutynes are about 70 kcal/mol greater than for acetylene. The energies of a process by which perfluorocyclobutyne might be formed are also calculated.
Citation
Journal of the Chemical Society-Perkin Transactions 2
Volume
No. 11

Keywords

Ab Initio, carbenes, cyclobutyne, rearrangement

Citation

Wiberg, K. , Marquez, M. and Gonzalez, C. (1999), Rearrangement of Perfluorocyclobutyne, Journal of the Chemical Society-Perkin Transactions 2 (Accessed July 16, 2024)

Issues

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Created October 31, 1999, Updated October 12, 2021