Simultaneous Tunneling Control in Conformer-Specific Reactions

Nunes C. M., Roque J. P. L., Doddipatla S., Wood S. A., McMahon R. J., Fausto R.

JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, vol.144, no.45, pp.20866-20874, 2022 (SCI-Expanded) identifier identifier identifier

  • Publication Type: Article / Article
  • Volume: 144 Issue: 45
  • Publication Date: 2022
  • Doi Number: 10.1021/jacs.2c09026
  • Journal Name: JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Academic Search Premier, Applied Science & Technology Source, Aqualine, Aquatic Science & Fisheries Abstracts (ASFA), Artic & Antarctic Regions, BIOSIS, Biotechnology Research Abstracts, Chemical Abstracts Core, Chimica, Compendex, Computer & Applied Sciences, EMBASE, MEDLINE, DIALNET
  • Page Numbers: pp.20866-20874
  • Istanbul Kültür University Affiliated: Yes

Abstract

We present here a new example of chemical reactivity governed by quantum tunneling, which also highlights the limitations of the classical theories. The syn and anti conformers of a triplet 2-formylphenylnitrene, generated in a nitrogen matrix, were found to spontaneously rearrange to the corresponding 2,1-benzisoxazole and imino-ketene, respectively. The kinetics of both transformations were measured at 10 and 20 K and found to be temperature-independent, providing clear evidence of concomitant tunneling reactions (heavy-atom and H atom). Computations confirm the existence of these tunneling reaction pathways. Although the energy barrier between the nitrene conformers is lower than any of the observed reactions, no conformational interconversion was observed. These results demonstrate an unprecedented case of simultaneous tunneling control in conformer-specific reactions of the same chemical species. The product outcome is impossible to be rationalized by the conventional kinetic or thermodynamic control.