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Complejos de cobre de ligandos tripodales N-heterocíclicos de carbenos anclados con nitrógeno
Xile Hu1, Ingrid Castro-Rodriguez, Karsten Meyer
1Department of Chemistry and Biochemistry, Mail Code 0358, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093-0358, USA.
Journal of the American Chemical Society
|October 2, 2003
Resumen
Los investigadores desarrollaron nuevos ligandos N-anclados de tetradentato tris-carbeno, TIMEN, para la complejación de metales. Estos ligandos forman complejos de cobre trinucleares y mononucleares únicos, que muestran coordinación sintonizable y propiedades redox para los estados de cobre (I) y cobre (II).
Área de la Ciencia:
- Coordinación Química de la Coordinación
- Química organometálica Química orgánica de los metales.
- Diseño del ligando diseño de ligandos.
Sus antecedentes:
- Los carbenos N-heterocíclicos (NHC) son ligandos versátiles en la química de la coordinación.
- Los ligandos trípodos ofrecen entornos de coordinación únicos para los iones metálicos.
- El desarrollo de ligandos tetradentados es crucial para estabilizar varios estados de oxidación de los metales.
Objetivo del estudio:
- Para sintetizar y caracterizar los nuevos ligandos N-anclados tetradentados tris-carbenos (TIMEN(R)).
- Para investigar el comportamiento de coordinación de los ligandos TIMEN (R) con el cobre (I) y la plata (I).
- Explorar las propiedades estructurales y electrónicas de los complejos metálicos resultantes.
Principales métodos:
- Síntesis de sales de imidazolio y tris-carbenos libres.
- Reacciones de complejación con sales de plata (I) y cobre (I).
- Elucidación estructural utilizando difracción de rayos X de un solo cristal.
- Estudios electroquímicos (potenciales de redox) y caracterización espectroscópica (EPR, SQUID).
Principales resultados:
- Se ha logrado la síntesis de los ligandos TIMEN (R) (R = Me, t-Bu, Bz).
- Formación de un complejo trinuclear de cobre (I) con TIMEN (Me) y de complejos de cobre (I) mononucleares con TIMEN (t-Bu) y TIMEN (Bz).
- Las estructuras de rayos X revelan diversas geometrías de coordinación: planas en forma de T, lineales y trigonales con interacción axial N.
- Los complejos 11b y 11c exhiben eventos de redox reversibles de un electrón, estabilizando los estados Cu (I) / Cu (II).
- Síntesis y caracterización de un complejo de cobre (II) y cobre (Cu) y cobre (OTf) y cobre (Bz) y cobre (TIMEN) y cobre (Bz) y cobre (Cu) y cobre (OTf) y cobre (Bz) y cobre (TIMEN) y cobre (Bz)) y cobre (Cu) y cobre (OTf) y cobre (OTf) y cobre (TIMEN) y cobre (Bz))
Conclusiones:
- Los ligandos TIMEN(R) representan una nueva clase de N-anclado tetradentado tris-carbenos.
- La estructura del ligando dicta la nuclealidad y la geometría de coordinación de los complejos de cobre.
- Los ligandos TIMEN ((R) demuestran una importante flexibilidad electrónica y estructural, permitiendo la estabilización de los estados de oxidación tanto del cobre (I) como del cobre (II).
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