Chirality without Stereoisomers: Insight from the Helical Response of Bond Electrons

Tianlv Xu, Xing Nie, Shuman Li, Yong Yang, Herbert Früchtl, Tanja van Mourik, Steven R. Kirk, Martin J. Paterson, Yasuteru Shigeta, Samantha Jenkins

Research output: Contribution to journalArticlepeer-review

Abstract

The association between molecular chirality and helical characteristics known as the chirality-helicity equivalence is determined for the first time by quantifying a chirality-helicity measure consistent with photoexcitation circular dichroism experiments. This is demonstrated using a formally achiral SN2 reaction and a chiral SN2 reaction. Both the achiral and chiral SN2 reactions possess significant values of the chirality-helicity measure and display a Walden inversion, i. e. an inversion of the chirality between the reactant and product. We also track the chirality-helicity measure along the reaction path and discover the presence of chirality at the transition state and two intermediate structures for both reactions. We demonstrate the need for the chirality-helicity measure to differentiate between steric effects due to eclipsed conformations and chiral behaviors in formally achiral species. We explain the significance of this work for asymmetric synthetic reactions including the intermediate structures where the Cahn-Ingold-Prelog (CIP) rules cannot be used.

Original languageEnglish
JournalChemPhysChem
Early online date16 Jul 2021
DOIs
Publication statusE-pub ahead of print - 16 Jul 2021

Keywords

  • S 2 reaction
  • Walden inversion
  • asymmetric catalysis
  • molecular chirality
  • next generation QTAIM

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics
  • Physical and Theoretical Chemistry

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