Transition-state geometry measurements from (13)c isotope effects. The experimental transition state for the epoxidation of alkenes with oxaziridines.
We here suggest and evaluate a methodology for the measurement of specific interatomic distances from a combination of theoretical calculations and experimentally measured (13)C kinetic isotope effects. This process takes advantage of a broad diversity of transition structures available for the epoxidation of 2-methyl-2-butene with oxaziridines. From the isotope effects calculated for these transition structures, a theory-independent relationship between the C-O bond distances of the newly forming bonds and the isotope effects is established. Within the precision of the measurement, this relationship in combination with the experimental isotope effects provides a highly accurate picture of the C-O bonds forming at the transition state. The diversity of transition structures also allows an evaluation of the Schramm process for defining transition-state geometries on the basis of calculations at nonstationary points, and the methodology is found to be reasonably accurate.
Hirschi
Jennifer S
JS
Department of Chemistry, Texas A&M University, College Station, Texas 77842, USA.
Takeya
Tetsuya
T
Hang
Chao
C
Singleton
Daniel A
DA
D000475:Alkenes / Q000737:chemistry*; D001388:Aziridines / Q000737:chemistry*; D002247:Carbon Isotopes; D004852:Epoxy Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D008958:Models, Molecular; D013816:Thermodynamics
D000475:Alkenes; D001388:Aziridines; D002247:Carbon Isotopes; D004852:Epoxy Compounds