Our group has recently described a new form of kinetic isotope effect that arises
from dynamic selectivity in the bifurcation of a reaction pathway on the slope of an
energy surface. Since the selection between products does not occur at a potential energy
saddle point, we proposed that the isotope effect is decided by dynamic factors that are
not necessarily related to zero point energy effects on the surface. As an alternative
explanation, it has recently been suggested that variational transition state theory can
account for these isotope effects. The dynamic explanation and variational transition state
theory explanation make distinct predictions as to the temperature dependence of these
isotope effects. I describe here my studies of the temperature dependence of the
intramolecular isotope effects for the reaction of singlet oxygen with gemtetramethylethylene-
d6. The selectivity observed for this reaction across a broad
temperature range is clearly a non-Eyring distribution and thus the mechanism cannot be
adequately described solely using transition state theory or even some variation of it.
After using these results to evaluate competing theories it was concluded that this
mechanism could only be properly understood using a dynamic explanation.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/ETD-TAMU-1057 |
| Date | 15 May 2009 |
| Creators | Ruiz, N. Rebecca |
| Contributors | Singleton, Daniel A. |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Thesis, text |
| Format | electronic, application/pdf, born digital |
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