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Inusual estructura electrónica de la primera fila de complejos de metales de transición que contienen dipirrometano y
Evan R King1, Theodore A Betley
1Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, 306E Mallinckrodt, Cambridge, Massachusetts 02138, USA.
Journal of the American Chemical Society
|October 8, 2009
Resumen
Nuevos complejos de metales de transición con un ligando de dipirrometano muestran un modo de coordinación único. Su estructura electrónica y sus vías de oxidación están basadas en ligandos, independientemente del ion metálico, la geometría o el estado de espín.
Área de la Ciencia:
- Coordinación Química de la Coordinación
- Química organometálica Química orgánica de los metales.
- Ciencia de los materiales Ciencia de los materiales.
Sus antecedentes:
- Los ligandos de dipirrometano son versátiles bloques de construcción en la química de la coordinación.
- El obstáculo estérico de los sustituyentes de arilo puede influir en los modos de coordinación de los metales.
- La comprensión de las estructuras electrónicas de los complejos metálicos es crucial para la catálisis y las aplicaciones de materiales.
Objetivo del estudio:
- Para sintetizar y caracterizar complejos de metales de transición de 1,9-dimesityl-5,5-dimethyldipyrromethane (dpm). para sintetizar y caracterizar complejos de metales de transición de 1,9-dimesityl-5,5-dimethyldipyrromethane (dpm). para sintetizar y caracterizar complejos de metales de transición de 1,9-dimesityl-5,5-dimethyldipyrromethane (dpm). para sintetizar y caracterizar complejos de metales de transición de 1,9-dimesityl-5,5-dimethyldipyrromethane (dpm).
- Investigar el comportamiento de coordinación y las propiedades electrónicas de estos complejos.
- Explorar las vías de oxidación electroquímica dentro del marco del ligando dpm.
Principales métodos:
- Síntesis de complejos de metales de transición (de Mn a Zn) con el ligando dpm.
- Difracción de rayos X para la determinación estructural.
- Espectroscopia SQUID y EPR para la caracterización magnética.
- Voltametría de pulso diferencial para el análisis electroquímico.
- Teoría Funcional de Densidad (DFT) para el cálculo de la estructura electrónica.
Principales resultados:
- El ligando dpm adopta un modo de coordinación eta(1),eta(1) debido al obstáculo estérico.
- Los complejos de Mn (II), Fe (II) y Co (II) son de alto espín y pseudotetraédricos.
- El complejo Ni (II) es de baja espina y cuadrado-planar.
- Se observó una vía común de oxidación basada en ligandos de dos electrones en toda la serie.
- Los cálculos de DFT confirmaron que los orbitales moleculares más altos están basados en ligandos.
Conclusiones:
- La estructura electrónica y el comportamiento de oxidación de estos complejos metálicos dpm están dictados principalmente por el ligando, no por el centro metálico.
- El marco dpm proporciona una plataforma estable para complejos metálicos redox-activos.
- No se observó actividad redox intramolecular ni tautomerismo de estado de espín dentro de esta serie.
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