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Actividad redox de ligandos de complejos orgánicos de radicales regidos por la geometría
Gregory A Dawson1, Qiao Lin1, Michelle C Neary2
1Department of Chemistry, New York University, 100 Washington Square East, New York, New York 10003, United States.
Journal of the American Chemical Society
|September 11, 2023
Resumen
Los investigadores sintetizaron y caracterizaron complejos de radicales de níquel. Encontraron que los ligandos N en complejos de cuatro coordenadas son redox-activos, formando radicales centrados en los ligandos, a diferencia de los complejos de tres coordenadas.
Área de la Ciencia:
- Química organometálica
- Catálisis
- La Química Radical
Sus antecedentes:
- Los catalizadores de níquel son cruciales para las reacciones de acoplamiento cruzado, a menudo utilizando ligandos N bidentados para permitir vías radicales.
- Los complejos orgánicos de radicales de níquel se proponen como intermediarios en estos ciclos catalíticos, pero sus estructuras electrónicas no se comprenden completamente.
Objetivo del estudio:
- Síntesis y caracterización de complejos de radicales de níquel orgánico apoyados por N-ligandos bidentados (bpy, fen, pirox).
- Establecer una regla empírica para las estructuras electrónicas de estos complejos de radicales de níquel.
- Aclarar el papel de los ligandos N en la estabilización de los radicales de níquel intermedios durante la catálisis.
Principales métodos:
- Síntesis y caracterización de una serie de complejos orgánicos de radicales de níquel.
- Estudios espectroscópicos y electroquímicos para determinar las estructuras electrónicas.
- Análisis comparativo de complejos de cuatro coordenadas (planos cuadrados) y de tres coordenadas (planos trigonales).
Principales resultados:
- Estableció una regla empírica para las estructuras electrónicas de los complejos de radicales de níquel.
- Actividad redox observada en los ligandos N de los complejos de cuatro coordenadas, lo que lleva a radicales centrados en los ligandos.
- No se encontró actividad redox de ligandos en complejos de tres coordenadas, que se describen mejor como radicales centrados en níquel.
Conclusiones:
- La actividad redox de los ligandos N depende de la geometría de coordinación del complejo de radicales de níquel.
- La actividad redox del ligando influye en la naturaleza del radical (centrado en el ligando frente al níquel).
- Los conocimientos sobre los intermediarios estabilizadores de radicales de níquel pueden ayudar a desarrollar catalizadores de níquel optimizados para el acoplamiento cruzado.
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