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Se ha observado directamente la eliminación reductora de haluros de arilo de los complejos monoméricos de arilpaladio
1Department of Chemistry, Yale University, P.O. Box 208107, New Haven, CT 06520-8107, USA.
Journal of the American Chemical Society
|November 13, 2003
Resumen
Los complejos de haluro de arilo del paladio (II) se someten a una eliminación reductora. Las propiedades electrónicas de los halogenuros, no la termodinámica, dictan las tasas de eliminación reductora de los cloruros de arilo, bromuros y yoduros.
Área de la Ciencia:
- Química organometálica Química orgánica de los metales.
- La catálisis de la catálisis.
- Mecanismos de reacción Mecanismos de reacción
Sus antecedentes:
- Los complejos monoméricos de arilpaladio ((II) halogenado de tres coordenadas son intermediarios clave en varios procesos catalíticos.
- La eliminación reductiva del haluro de arilo de los complejos de paladio forma haloareno y Pd(0).
Objetivo del estudio:
- Investigar la eliminación reductiva de haluros de arilo (cloruros, bromuros, yoduros) de los complejos de paladio (II).
- Determinar los factores que controlan las velocidades y la termodinámica de estas reacciones.
Principales métodos:
- Síntesis de complejos monoméricos de arilpaladio (II) halogenado con ligando P (t-Bu) 3.
- Observación de la eliminación reductora tras la adición de P(t-Bu) 3.
- Establecimiento de condiciones de equilibrio para la eliminación reductora y la adición oxidativa con cinco haloarenas.
Principales resultados:
- Se observó una eliminación reductiva de cloruros de arilo, bromuros y yoduros.
- Favorabilidad termodinámica para la eliminación reductora: cloruro > bromuro > yoduro.
- Las tasas cinéticas para la eliminación reductora: bromuro > yoduro > cloruro.
- Propiedades electrónicas de haluros, no fuerza motriz termodinámica, velocidades de reacción de control.
Conclusiones:
- Las propiedades electrónicas del ligando halogenado son el principal determinante de las tasas de eliminación reductoras en los complejos de arilpaladio (II).
- Los estudios mecanicistas sugieren una etapa de coordinación de limitación de la tasa que involucra a P ((t-Bu) 3 después de la eliminación reductiva inicial.
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