intramolecular isotope effect
A kinetic isotopic effect observed when a single substrate, in which the isotopic atoms occupy equivalent reactive positions, reacts to produce a non-statistical distribution of isotopomeric products. In such a case the isotope effect will favour the pathway with lower force constants for displacement of the isotopic nuclei in the transition state.
PAC, 1994, 66, 1077. 'Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994)' on page 1130 (