| Popis: |
Gas-phase 1H NMR spectra of a sample containing 4 Torr of trimethylsilylcyclopentadiene, 1 Torr of CHCl3, and 707 Torr SF6 show exchange broadened line shapes consistent with the degenerate migration of the trimethylsilyl group in the 5-isomer via 1-2 sigmatropic shifts. The kinetic parameters for this process in the gas phase, Δ H ‡ =15.4(0.2) kcal mol −1 , Δ S ‡ =−1.1(0.1) kcal mol −1 , and Δ G ‡ =15.7 kcal mol −1 are slightly higher than values reported previously for the neat liquid. The small solvent effect observed indicates that a large charge separation in the transition state is unlikely. |
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