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Síntesis y estructuras moleculares y electrónicas de los complejos de dinitrógeno de cobalto bis ((imino) piridina
Amanda C Bowman1, Carsten Milsmann, Crisita Carmen Hojilla Atienza
1Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853, USA.
Journal of the American Chemical Society
|January 21, 2010
Resumen
Este estudio detalla la síntesis de complejos neutros de dinitrógeno de cobalto a través de la reducción por amalgama de sodio. Estos complejos, que presentan ligandos de bis ((imino) piridina, exhiben estados de oxidación Co ((I) y estados de doble fundamento, con una mayor reducción que produce aniones de dinitrógeno de cobalto.
Área de la Ciencia:
- Química organometálica Química orgánica de los metales.
- Coordinación Química de la Coordinación
- Síntesis Inorgánica y Síntesis Inorgánica.
Sus antecedentes:
- Los ligandos de bis ((imino) piridina son andamios versátiles en la química de los metales básicos.
- Los complejos de cobalto con ligandos de nitrógeno son de interés para aplicaciones catalíticas y electrónicas.
- La comprensión de los procesos redox en los sistemas de cobalto-nitrógeno es crucial para la reactividad.
Objetivo del estudio:
- Para sintetizar y caracterizar complejos neutros de dinitrógeno de cobalto utilizando ligandos de bis(imino) piridina sustituidos por arilo.
- Para investigar la estructura electrónica y los estados de oxidación de estos nuevos complejos de cobalto.
- Explorar la reducción secuencial de las especies de dinitrógeno de cobalto y sus propiedades electrónicas.
Principales métodos:
- Síntesis de complejos de dihaluro de cobalto con ligandos de bis ((imino) piridina.
- Reducción de amalgama de sodio bajo atmósfera de nitrógeno para formar complejos de dinitrógeno de cobalto.
- Mediciones de susceptibilidad magnética, difracción de rayos X, espectroscopia EPR y cálculos de DFT.
Principales resultados:
- Se sintetizaron con éxito los complejos neutros de dinitrógeno de cobalto, ((Ar) PDI) CoN(2) y ((iPr) BPDI) CoN(2).
- Los datos magnéticos y cristalográficos confirman los estados de base dobles y un estado de oxidación Co (I), consistente con la reducción de quelato de un electrón.
- La espectroscopia EPR indica un orbital molecular ocupado de forma individual (SOMO) basado en bis ((imino) piridina, y una mayor reducción produce aniones de dinitrógeno de cobalto.
Conclusiones:
- Las reducciones secuenciales de un electrón de los compuestos de dinitrógeno bis ((imino) piridina cobalto conducen a centros Co ((I) con acumulación de electrones centrados en el quelato.
- Los cálculos de DFT reproducen con precisión las frecuencias de estiramiento NN experimentales, validando el enfoque computacional.
- El estudio proporciona información sobre las estructuras electrónicas de los complejos de dinitrógeno de cobalto reducido y la influencia del diseño del ligando en el comportamiento redox del metal.
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