Isotope effect perturbation treatment

As already indicated above, kinetic studies of steric isotope effects afford a possibility of testing our present ideas about the transition state. Bartell s perturbation treatment (Section II, A) involves a timeaveraging of the repulsion energy with respect to the ordinary vibrational motion within the transition state. The passage through the... 

Prakash et al. (1985) used the deuterium isotope effect on the l3C NMR spectrum of [47] to provide further evidence for the symmetrical, homoaromatic nature of this ion. They prepared the specifically deuterated trishomocyclopropenyl cation [57] by superacid treatment of the corresponding alcohol [58]. The 13C NMR spectrum of [57] displayed a triplet for the deuterated methine only 0.2 ppm to higher field than the undeuterated methine, indicating only an isotopic perturbation of resonance and not a rapidly equilibrating classical ion system (see Siehl, 1987). 

---