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Energéticas de la activación del enlace C-H de los hidrocarburos aromáticos fluorados utilizando un complejo [Tp'Rh
Meagan E Evans1, Catherine L Burke, Sornanong Yaibuathes
1Department of Chemistry, University of Rochester, Rochester, New York 14627, USA.
Journal of the American Chemical Society
|August 28, 2009
Resumen
El efecto de ortofluoruro estabiliza significativamente los enlaces rodio-carbono en los hidrocarburos aromáticos fluorados. Este estudio cuantifica este efecto, revelando su impacto en la activación de enlaces C-H y las barreras de eliminación reductiva.
Área de la Ciencia:
- Química organometálica Química orgánica de los metales.
- Química del flúor Química del flúor
- La catálisis es la catálisis.
Sus antecedentes:
- La activación del enlace C-H es una transformación crucial en la química sintética.
- Los hidrocarburos aromáticos fluorados presentan propiedades electrónicas únicas que influyen en la reactividad.
- Los complejos de rodio son catalizadores efectivos para la activación de C-H.
Objetivo del estudio:
- Investigar el impacto de los sustitutos del flúor en la estabilidad de los enlaces rodio-arilo formados a través de la activación de C-H.
- Para cuantificar experimentalmente el efecto del ortofluoro sobre la fuerza del enlace Rh-C.
- Para comparar hallazgos experimentales con predicciones teóricas.
Principales métodos:
- Activación del enlace C-H de hidrocarburos aromáticos fluorados utilizando un complejo [Tp'Rh ((CNneopentyl)).
- Síntesis y caracterización de los productos Tp'Rh ((CNneopentilo)) ((arilo)) ((F)) H.
- Experimentos de competencia y medición de las barreras de activación (DeltaG) para determinar la fuerza relativa de los enlaces.
Principales resultados:
- Se observó la formación de productos a través de la activación C-H de las arenas fluoradas.
- La estabilidad de los enlaces Rh-C ((arilo) depende en gran medida del número de ortofluorinas y no del número total de fluorinas.
- Los complejos con dos ortofluorinas exhibieron mayores barreras de eliminación reductoras (~5 kcal mol(-1)) en comparación con aquellos con uno.
- Las fuerzas experimentales de enlace Rh-C se correlacionaron bien con las fuerzas teóricas de enlace C-H (pendiente experimental 2.14 frente a la teórica 1.96).
Conclusiones:
- El efecto de orto flúor fortalece significativamente el enlace Rh-C (arilo).
- Este estudio proporciona la primera cuantificación experimental del efecto del ortofluoruro en la fuerza del enlace metal-carbono, alineándose con las predicciones teóricas.
- Los hallazgos ofrecen información sobre el control de la reactividad en la catálisis organometálica que involucra sustratos fluorados.
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