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(2 + 2) Cicloadición de benceno a los metalofullerenos endohedrales M3N@C80 (M = Sc, Y): Un mecanismo intermedio

Tao Yang¹, Shigeru Nagase², Takeshi Akasaka³

¹‡Institute for Molecular Science, Okazaki 444-8585, Japan.

Journal of the American Chemical Society

|May 15, 2015

Resumen

Los cálculos funcionales de densidad revelan que las cicloadiciones de benceno a los metallofulérenos siguen un mecanismo diradical. El cúmulo endohedral influye en la regioselectividad y la estructura de la jaula, con Sc3N@C80 favoreciendo los aductos de jaula cerrada y Y3N@C80 produciendo estructuras de jaula abierta.

Área de la Ciencia:

Química computacional es la química computacional.
Ciencia de los materiales Ciencia de los materiales.
Química orgánica es la química orgánica.

Sus antecedentes:

Los metalofullerenos endohedrales (EMF) exhiben propiedades electrónicas y estructurales únicas.
La cicloadición (2+2) del benceno ofrece una vía versátil para funcionalizar las jaulas de fullereno.

Objetivo del estudio:

Para dilucidar el mecanismo de reacción y la regioselectividad de la cicloadición de benzina a M3N@C80 (M = Sc, Y).
Investigar la influencia del racimo endohedral en las vías de reacción y estructuras de productos.

Principales métodos:

Se emplearon cálculos de la teoría funcional de la densidad (DFT).
Análisis de las vías de reacción, estados de transición y estructuras intermedias.
Evaluación del control cinético y termodinámico.

Principales resultados:

La reacción procede a través de un mecanismo diradical, con la formación de intermedios como el paso que determina la velocidad.
La regioselectividad se rige por el sitio de la formación diradical y la posterior isomerización.
Sc3N@C80 favorece [5,6] benzoadducts (jaula cerrada), mientras que Y3N@C80 produce tanto [5,6] y [6,6] benzoadducts (jaula abierta).
La energía de deformación local de la jaula de fullereno se identifica como el origen de la regioselectividad.

Conclusiones:

El mecanismo diradical dicta el resultado de la cicloadición.
Los grupos endoderales juegan un papel crucial en el control de la regioselectividad y la topología del conducto de carga cíclica.
Este estudio presenta la primera instancia de un cúmulo endodedral que induce un cambio de benzoaductos de jaula cerrada a los de jaula abierta.

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