Isotopenstörung zum nachweis einer cope-umlagerung bei semibullvalenen

Askani, R.; Kalinowski, H.‐O.; Pelech, B.; Weuste, Burkhard

doi:10.1016/s0040-4039(01)80245-8

Cited by 18 publications

(1 citation statement)

References 17 publications

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“…Askani et al demonstrated that the isotopomers of CD 3 -2a differ in ZPVE by approx. 0.01 kcal mol À1 , [35] nearly one order of magnitude less than the corresponding isotopomers of d 1 -2a,w hichb arely dependso nt he degree of deuteration( for an extended discussion, see Supporting Information) or symmetry (Table 4).…”

Section: Influence Of the Thermodynamic Drivingforcementioning

confidence: 95%

Heavy‐Atom Tunneling in Semibullvalenes: How Driving Force, Substituents, and Environment Influence the Tunneling Rates

Schleif

Tatchen

Rowen

et al. 2020

Chemistry A European J

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The Cope rearrangement of selectively deuterated isotopomers of 1,5‐dimethylsemibullvalene 2 a and 3,7‐dicyano‐1,5‐dimethylsemibullvalene 2 b were studied in cryogenic matrices. In both semibullvalenes the Cope rearrangement is governed by heavy‐atom tunneling. The driving force for the rearrangements is the small difference in the zero‐point vibrational energies of the isotopomers. To evaluate the effect of the driving force on the tunneling probability in 2 a and 2 b, two different pairs of isotopomers were studied for each of the semibullvalenes. The reaction rates for the rearrangement of 2 b in cryogenic matrices were found to be smaller than the ones of 2 a under similar conditions, whereas differences in the driving force do not influence the rates. Small curvature tunneling (SCT) calculations suggest that the reduced tunneling rate of 2 b compared to that of 2 a results from a change in the shape of the potential energy barrier. The tunneling probability of the semibullvalenes strongly depends on the matrix environment; however, for 2 a in a qualitatively different way than for 2 b.

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Section: Influence Of the Thermodynamic Drivingforcementioning

confidence: 95%