Competitive Nitrogen versus Carbon TunnelingClick to copy article linkArticle link copied!
- Cláudio M. Nunes*Cláudio M. Nunes*[email protected]CQC, Department of Chemistry, University of Coimbra, 3004-535 Coimbra, PortugalMore by Cláudio M. Nunes
- André K. EckhardtAndré K. EckhardtInstitute of Organic Chemistry, Justus Liebig University, Heinrich-Buff-Ring 17, 35392 Giessen, GermanyMore by André K. Eckhardt
- Igor RevaIgor RevaCQC, Department of Chemistry, University of Coimbra, 3004-535 Coimbra, PortugalMore by Igor Reva
- Rui FaustoRui FaustoCQC, Department of Chemistry, University of Coimbra, 3004-535 Coimbra, PortugalMore by Rui Fausto
- Peter R. Schreiner*Peter R. Schreiner*[email protected]Institute of Organic Chemistry, Justus Liebig University, Heinrich-Buff-Ring 17, 35392 Giessen, GermanyMore by Peter R. Schreiner
Abstract

Quantum mechanical tunneling (QMT) of heavy atoms like carbon or nitrogen has been considered very unlikely for the longest time, but recent evidence suggests that heavy-atom QMT does occur more frequently than typically assumed. Here we demonstrate that carbon vs nitrogen heavy-atom QMT can even be competitive leading to two different products originating from the same starting material. Amino-substituted benzazirine was generated in solid argon (3–18 K) and found to decay spontaneously in the dark, with a half-life of 210 min, to p-aminophenylnitrene and amino-substituted ketenimine. The reaction rate is independent of the cryogenic temperature, in contradiction to the rules inferred from classical transition state theory. Quantum chemical computations confirm the existence of two competitive carbon vs nitrogen QMT reaction pathways. This discovery emphasizes the quantum nature of atoms and molecules, thereby enabling a much higher level of control and a deeper understanding of the factors that govern chemical reactivity.
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