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UDFT y MCSCF descripciones de la fotoquímica ciclización de Bergman de las enediynes
A E Clark1, E R Davidson, J M Zaleski
1Department of Chemistry, Indiana University, Bloomington, IN 47405-7102, USA.
Journal of the American Chemical Society
|July 18, 2001
Resumen
La ciclización de Bergman del cis-1,5-hexadiyne-3-eno es poco probable a través del estado triple (13B) debido a la isomerización y la abstracción de hidrógeno que compiten. La ciclización fotoquímica es más plausible en la superficie de energía potencial singlet (21A).
Área de la Ciencia:
- Química computacional es la química computacional.
- Fotoquímica orgánica y fotoquímica orgánica.
Sus antecedentes:
- La ciclización de Bergman es una reacción clave en la química orgánica para la formación de intermediarios de p-benceno.
- Comprender las superficies de energía potencial (PES) es crucial para predecir las vías de reacción y la viabilidad.
Objetivo del estudio:
- Para investigar las superficies de energía potencial para la ciclización de Bergman de cis-1,5-hexadiina-3-ene.
- Para determinar la vía de ciclización fotoquímica más plausible.
Principales métodos:
- Utilizó varios métodos de química computacional, incluidos UDFT, CI, CASCI, CASSCF y CASMP2.
- Superficies de energía potencial (PES) singlet y triplet calculadas para la reacción.
Principales resultados:
- La vía del estado triple (13B) es improbable debido a la isomerización cis-trans y la abstracción de átomos de hidrógeno.
- La superficie de energía potencial singlet (21A) ofrece una ruta de ciclización fotoquímica más plausible, aunque menos exotérmica.
- El intermedio p-benceno exhibe una estructura electrónica única con características tanto de carbenos individuales como de diradicales.
Conclusiones:
- La ciclización de Bergman de cis-1,5-hexadiina-3-eno no es favorecida en la vía del triplete.
- La ciclización fotoquímica tiene más probabilidades de ocurrir en el singlet (21A) PES.
- La estructura electrónica del intermediario p-benceno es compleja, lo que influye en la dinámica de la reacción.
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