Unveiling a flip-over retention mechanism in the gas-phase Cl<sup>-</sup> + (CH<sub>3</sub>)<sub>3</sub>CI S<sub>N</sub>2 reaction.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 42067528.
- Also identified by DOI 10.1038/s41467-026-72121-4 and PMC identifier 13134954.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Bimolecular nucleophilic substitution (S<sub>N</sub>2) and base-induced elimination (E2) reactions play crucial roles in chemistry. Here, we report a combined study of ion-molecule crossed-beam 3D velocity map imaging experiments and dynamics simulations on an accurate 39-dimensional potential energy surface for the Cl<sup>-</sup> + (CH<sub>3</sub>)<sub>3</sub>CI reaction, allowing the most rigorous investigation of the atomistic dynamics. Good agreement between experimental and theoretical product angular and energy distributions is achieved, revealing that predominantly direct E2 reactions produce the majority of highly excited neutral products and slow ion product distributions. Moreover, we uncover a direct "flip-over" retention mechanism for the S<sub>N</sub>2 reaction, where substitution occurs via the direct flipping of the tert-butyl group, leading to retention of the tetrahedral carbon center. This mechanism manifests as a predominant forward-scattering feature in the product angular distribution and provides an important perspective on substitution dynamics in organic reactions.