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Reacción de la superficie de relojería por rotación del producto en el plano
Kelvin Anggara1, Kai Huang1, Lydie Leung1
1Lash Miller Chemical Laboratories, Department of Chemistry and Institute of Optical Sciences, University of Toronto , 80 Saint George Street, Toronto, Ontario M5S 3H6, Canada.
Journal of the American Chemical Society
|May 19, 2016
Resumen
Las reacciones inducidas por electrones del metadiobenzeno en las superficies de cobre revelan mecanismos distintos, sucesivos y concertados. La dinámica molecular muestra que las vías de reacción dependen del intermediario de iodofenilo
Área de la Ciencia:
- Ciencias de la superficie
- Física y química
- Ciencias de los materiales
Sus antecedentes:
- Comprender las reacciones inducidas por electrones en superficies es crucial para la electrónica molecular y la química de superficies.
- Las moléculas físicamente absorbidas en las superficies metálicas ofrecen vías de reacción únicas influenciadas por las interacciones del sustrato.
Objetivo del estudio:
- Investigar los mecanismos de reacción inducida por electrones del metadiobenzeno (mDIB) en una superficie de Cu{110) a bajas temperaturas.
- Diferenciar entre vías de reacción sucesivas y concertadas y sus distribuciones de productos resultantes.
- Utilizar la dinámica molecular para explicar las diferencias observadas en los resultados de la reacción.
Principales métodos:
- Se utilizó la microscopía de túnel de barrido (STM) para obtener imágenes de estructuras moleculares y productos de reacción.
- Se emplearon simulaciones de dinámica molecular para modelar las vías de reacción y la dinámica.
- Los experimentos se llevaron a cabo a temperaturas criogénicas (4,6 K) para controlar el movimiento molecular.
Principales resultados:
- Se identificaron dos mecanismos de reacción distintos, sucesivos y concertados, para la disociación de mDIB.
- El mecanismo sucesivo implicó la ruptura secuencial del enlace C-I, lo que permitió la rotación intermedia del iodofenilo.
- El mecanismo concertado incluía la ruptura simultánea del enlace C-I, con productos que reflejaban el mDIB no rotado.
- La dinámica molecular confirmó que el retraso de tiempo entre los eventos de ruptura de enlaces dicta la extensión de la rotación intermedia.
Conclusiones:
- La dinámica de rotación del intermediario de iodofenilo actúa como un "reloj" para el tiempo de reacción.
- La diferencia en las distribuciones de productos se debe al tiempo disponible para la rotación intermedia entre los eventos de ruptura de vínculos.
- Este estudio presenta un nuevo método para "relojar" la dinámica sub-picosegundo mediante el análisis de las distribuciones de productos de reacción.
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