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Estructuras electrónicas y perfiles de reactividad de los complejos de dicobre con puente de nitrógeno de arilo
Kurtis M Carsch1, James T Lukens2, Ida M DiMucci2
1Department of Chemistry and Chemical Biology , Harvard University , 12 Oxford Street , Cambridge , Massachusetts 02138 , United States.
Journal of the American Chemical Society
|January 10, 2020
Resumen
Se sintetizaron y redujeron complejos de dicopero con ligandos de pacman-dipirrina. Los complejos de imida resultantes exhiben espín localizado por NAr, lo que permite una reactividad promovida por los radicales como la aminación C-H.
Área de la Ciencia:
- Química de coordinación
- Química organometálica
- Catálisis
Sus antecedentes:
- Los andamios de ligandos de dipirrina de pacman dinucleados son efectivos para la plantilla de complejos de dicobre.
- La síntesis de complejos de imida neutra (Rdmx) Cu2 ((μ2-NAr) incluye precursores de dicupro y azidas de arilo.
Objetivo del estudio:
- Síntesis y caracterización de nuevos complejos de imida de dicopro.
- Investigar las estructuras electrónicas y la reactividad de los complejos reducidos de imida y iminyl de dicobre.
- Explorar la reactividad promovida por los radicales, incluida la aminación C-H, la transferencia de nitreno y la abstracción de átomos H.
Principales métodos:
- Síntesis de complejos de dicobre mediante desprotonación/metalización o transmetalización.
- Reducción de complejos de imida utilizando grafito de potasio u otros reductores químicos.
- Caracterización espectroscópica que incluye EPR, absorción de rayos X (Cu L2,3 / K-edge, N K-edge) y espectroscopia óptica.
- Análisis computacional mediante cálculos DFT/CASSCF.
Principales resultados:
- Los complejos de imida neutrales (Rdmx) Cu2 ((μ2-NAr) fueron sintetizados con éxito.
- La reducción de un electrón de un complejo específico inició la aminación bencílica C-H intramolecular.
- La reducción química produjo complejos de iminyl aislables [(Rdmx) Cu2 ((μ2-NAr) ].
- Los complejos reducidos son formalmente de valencia mixta Clase IIIA con un espín significativo localizado en NAr.
- La reactividad está influenciada por los sustituyentes de arilo, afectando el carácter N-radical.
Conclusiones:
- Los complejos reducidos de imida de dicobre exhiben estructuras electrónicas y reactividad únicas.
- El espín localizado por NAr en complejos reducidos facilita las transformaciones promovidas por radicales.
- Los sustituyentes de arilo juegan un papel crucial en la sintonización del carácter y la reactividad de los radicales N de estos complejos.
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