A theoretical study on the reaction mechanism for the Bergman cyclization from the perspective of the electron localization function and catastrophe theory

Juan C. Santos, Juan Andres, Arie Aizman, Patricio Fuentealba, Victor Polo

Resultado de la investigación: Contribución a una revistaArtículorevisión exhaustiva

52 Citas (Scopus)

Resumen

The reaction mechanism associated with the Bergman cyclization of the (Z)-hexa-1,5-diyne-3-ene to render p-benzyne has been analyzed by means of a combined use of the electron localization function (ELF) and the catastrophe theory on the basis of density functional theory (DFT) calculations (B3LYP/6-31G(d)). The complex electronic rearrangements of this reaction can be highlighted using this novel quantum mechanical perspective. Five domains of structural stability of the ELF occurring along the intrinsic reaction path as well as four catastrophes (fold-cusp-fold-cusp) responsible for the changes in the topology of the system have been identified. The multiple factors that occur along the intrinsic reaction coordinate path are presented and discussed in a consistent way. The topological analysis of ELF and catastrophe theory reveals that mechanical deformation of the C1-C2-C3 unit and closed-shell repulsion between terminal acetylene groups lead to an early formation of diradicaloid character at C2 and C5 atoms. Immediately after the transition structure (TS) is reached, the open-shell-singlet biradical becomes stable. Meanwhile, C1 and C 6 atoms are preparing to be covalently bonded; that will finally occur at a distance of 1.791 Å. In addition, a separation of the ELF into in-plane (σ) and out-of-plane (π) contributions allows us to discuss the aromaticity profiles; σ-aromaticity appears in the vicinities of the TS, while π-aromaticity takes place in the final stage of the reaction path, once the ring has been formed.

Idioma originalInglés
Páginas (desde-hasta)3687-3693
Número de páginas7
PublicaciónJournal of Physical Chemistry A
Volumen109
N.º16
DOI
EstadoPublicada - 28 abr 2005

Áreas temáticas de ASJC Scopus

  • Química física y teórica

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