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Mecanismo completo de la hidroxilación aromática intramolecular sigma* a través de la activación de O2 por un

Albert Poater¹, Xavi Ribas, Antoni Llobet

¹Modeling Laboratory for Nanostructures and Catalysis (MoLNaC), Dipartimento di Chimica, Universita degli Studi di Salerno, via Ponte don Melillo, Fisciano (SA), 84084, Italy.

Journal of the American Chemical Society

|December 6, 2008

Resumen

Este estudio detalla el mecanismo de la hidroxilación aromática intramolecular utilizando un complejo de dicopro. Revela intermediarios clave como las especies superoxo y peroxo en la activación del oxígeno, guiando el diseño futuro del catalizador.

Área de la Ciencia:

Coordinación Química de la Coordinación
Química computacional es la química computacional.
La catálisis de la catálisis.

Sus antecedentes:

La hidroxilación aromática intramolecular es crucial en los sistemas biológicos y en la síntesis química.
Se sabe que los complejos hexaazamacrocíclicos de dicobre (I) activan el oxígeno.
Estudios experimentales previos caracterizaron el producto final pero no el mecanismo de reacción.

Objetivo del estudio:

Para dilucidar el mecanismo de reacción completo de la hidroxilación aromática intramolecular.
Para identificar los intermediarios clave en el proceso de activación de O2 por un complejo de dicopro.
Proporcionar ideas para el diseño de catalizadores más eficientes.

Principales métodos:

Cálculos de la Teoría Funcional de Densidad (DFT) utilizando el método B3LYP.
Investigación teórica de la vía de reacción desde la activación de O(2) hasta la formación del producto.
Análisis de las especies intermedias, incluidas las formas superoxo, peroxo y bis (mu-oxo).

Principales resultados:

Se forma inicialmente una especie Cu(I) Cu(II) -superoxo, seguida por un mu-eta(2):eta(2) -peroxo-Cu(II)(2) intermedio.
El peroxo intermedio es energéticamente cercano a una especie isomérica bis ((mu-oxo), con estabilidad dependiendo de los métodos de cálculo.
La reacción procede a través del ataque electrófilo, la formación de enlaces O-O y C-O, la liberación de protones y la reorganización hasta el producto final.

Conclusiones:

El estudio proporciona el primer mecanismo teórico detallado para la hidroxilación aromática intramolecular a través de la activación de O ((2) por un complejo de dicopro ((I)).
La presencia de un segundo anillo aromático puede facilitar la transferencia de protones, lo que sugiere una estrategia de diseño para mejorar la reactividad del catalizador.
La falta de barreras de alta energía y pozos profundos explica la dificultad experimental en la captura de intermedios.

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