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Síntesis y determinación de la estructura electrónica de las imidas de hierro bis(imino)piridina N-alquil-sustituidas
Amanda C Bowman1, Carsten Milsmann, Eckhard Bill
1Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853, USA.
Journal of the American Chemical Society
|October 12, 2011
Resumen
Los nuevos complejos de imida de hierro exhiben un comportamiento de cruce de espín, haciendo la transición entre estados de espín bajo y alto. Este comportamiento está influenciado por los sustituyentes de alquilo y proporciona información sobre su estructura electrónica y enlace.
Área de la Ciencia:
- Química organometálica Química orgánica de los metales.
- Coordinación Química de la Coordinación
- Ciencia de los materiales Ciencia de los materiales.
Sus antecedentes:
- Los ligandos de bis ((imino) piridina son andamios versátiles en la química de la coordinación.
- Los complejos de imida de hierro son de interés debido a sus diversas propiedades electrónicas y aplicaciones potenciales.
Objetivo del estudio:
- Para sintetizar y caracterizar los nuevos complejos de N-alquilo sustituido bis ((imino) piridina imida de hierro complejos.
- Para investigar el comportamiento de cruce de espín y la estructura electrónica de estos nuevos compuestos.
Principales métodos:
- Síntesis de complejos de imida de hierro a través de la adición de azido a un precursor de dinitrógeno de hierro.
- Caracterización mediante magnetometría SQUID, difracción de rayos X y espectroscopia de Mössbauer.
- Estudios computacionales y espectroscopia de absorción de rayos X para el análisis de la estructura electrónica.
Principales resultados:
- Se sintetizaron con éxito tres nuevos complejos de imida de hierro bis ((imino) piridina sustituidos por N-alquilo.
- El comportamiento de cruce de espín se observó en las imidas de hierro isoméricas, con una que muestra una transición más completa.
- La difracción de rayos X reveló estructuras planas con enlaces cortos Fe-N ((imida), lo que indica una reducción de dos electrones del ligando.
- La espectroscopia de Mössbauer confirmó los estados básicos diamagnéticos y apoyó el cruce de espín, lo que arrojó parámetros termodinámicos para la transición de S=0 a S=1.
Conclusiones:
- Los complejos sintetizados exhiben propiedades de cruce de espín sintonizables.
- La estructura electrónica se describe mejor como un centro férrico de bajo espín acoplado a un radical imidilo para el estado S = 0.
- Una transición de espín centrada en el hierro a un ión férrico de espín intermedio explica el estado S=1 a temperaturas más altas.
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