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Observación instantánea de rayos X de la brominación aromática mediada por paladio en un complejo poroso

Koki Ikemoto¹, Yasuhide Inokuma, Kari Rissanen

¹Department of Applied Chemistry, School of Engineering, The University of Tokyo , 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.

Journal of the American Chemical Society

|May 3, 2014

Resumen

Este estudio captura un intermediario transitorio de paladio durante la brominación aromática utilizando instantáneas de rayos X. Esto proporciona conocimientos mecanicistas cruciales sobre la catálisis del paladio y las vías de reacción.

Área de la Ciencia:

Química organometálica Química orgánica de los metales.
Química sintética de la química sintética.
Ciencia de los materiales Ciencia de los materiales.

Sus antecedentes:

La brominación aromática mediada por paladio es sintéticamente valiosa.
El mecanismo propuesto implica un ciclo catalítico raro de paladio (IV) / paladio (II).
La observación de los intermediarios transitorios en tales reacciones es un desafío.

Objetivo del estudio:

Para observar directamente el centro de reacción durante la brominación aromática mediada por paladio.
Para dilucidar el mecanismo de la brominación aromática utilizando un ciclo catalítico poco común.
Para demostrar la utilidad de las instantáneas de rayos X en el estudio de los mecanismos de reacción.

Principales métodos:

Utilizando un solo cristal de una red de coordinación porosa como un andamio cristalino.
Tratar el cristal con N-bromosuccinimida para iniciar la reacción.
Empleando instantáneas secuenciales de rayos X para capturar intermedios de reacción.

Principales resultados:

Se observó la conversión de una especie de aril-Pd(II) -L a un producto de aril bromado.
Se capturó una especie transitoria aryl-Pd(II) -Br, típicamente inobservable debido a la rápida dimerización.
Proporcionó una instantánea de rayos X del centro de reacción de paladio dentro del andamio cristalino.

Conclusiones:

El estado cristalino puede influir en la vía de reacción.
El método de instantánea de rayos X ofrece un nuevo enfoque para los estudios mecanicistas en sistemas heterogéneos.
La observación directa de especies transitorias proporciona valiosos conocimientos mecanicistas sobre la catálisis del paladio.

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