## inverse isotope effect

https://doi.org/10.1351/goldbook.I03142
A @[email protected] in which $$\frac{k^{\text{l}}}{k^{\text{h}}}<1$$, i.e. the heavier substrate reacts more rapidly than the lighter one, as opposed to the more usual 'normal' @[email protected], in which $$\frac{k^{\text{l}}}{k^{\text{h}}}>1$$. The @[email protected] will normally be 'normal' when the frequency differences between the isotopic @[email protected] are smaller than in the reactants. Conversely, an inverse @[email protected] can be taken as evidence for an increase in the corresponding @[email protected] on passing from the reactant to the @[email protected]
Source:
PAC, 1994, 66, 1077. (Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994)) on page 1130 [Terms] [Paper]