title: The normal range for secondary Swain-Schaad exponents without tunneling or kinetic complexity.
abstract: An analysis is presented of the range of secondary Swain-Schaad exponents to be expected at 25 degrees C in the absence of tunneling or kinetic complexity. From 15 996 sets of exact harmonic semiclassical equilibrium isotope effects for simple C-H/D/T exchange reactions and 954 sets of exact harmonic semiclassical secondary H/D/T kinetic isotope effects for C-H positions in simple organic reactions, the distribution of Swain-Schaad exponents versus magnitude of the isotope effect is determined. This distribution defines when a secondary Swain-Schaad exponent may be considered to implicate nonsemiclassical behavior, revises the expected Swain-Schaad exponent for extrapolation of secondary isotope effects, and serves as a guide to the uncertainty in such extrapolations.
authors.affiliation: Department of Chemistry, Texas A&M University, P.O. Box 30012, College Station, Texas 77842, USA.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Hirschi
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Singleton
mesh_terms: D006859:Hydrogen / Q000737:chemistry; D007700:Kinetics; D008956:Models, Chemical; D011789:Quantum Theory
chemical_list: D006859:Hydrogen