An inverse reactivity-selectivity relationship. Kinetic nitrogen isotope effects on methyl transfer to pyridines
Journal of Physical Chemistry
This paper reports that values of the 14N/15N rate constant ratio for methyl transfer to alkyl-substituted pyridines decrease (become more inverse) as CH3X becomes more reactive and may also decrease as the pyridine becomes more reactive. These changes in K14/K15 demonstrate increasing selectivity for 15N in preference to 14N as reactivity increases and thus are in violation of the reactivity-selectivity principle. However, these observed changes in K14/K15 are consistent with a very recent prediction that such ''anti-Hammond'' effects should result from changes in quantum mechanical mixing of configurations in the transition state and should dominate the more familiar effects of structural perturbations of the free energy surface.
Kurz, Joseph L, and Nasr, Moheb M., "An inverse reactivity-selectivity relationship. Kinetic nitrogen isotope effects on methyl transfer to pyridines" (1982). Faculty Scholarship. 288.