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La configuración electrónica y la naturaleza del ligando de los complejos de porfirina de hierro de cinco
Yulong Liu1, Wei Xu2, Jing Zhang2
1College of Materials Science and Optoelectronic Technology, University of Chinese Academy of Sciences , Yanqi Lake, Huairou District, Beijing 101408, China.
Journal of the American Chemical Society
|March 25, 2017
Resumen
Los complejos de porfirina de carbenos de hierro exhiben una configuración de hierro de espín bajo, confirmada por la espectroscopia Mössbauer. Estos estudios revelan la naturaleza covalente de los ligandos de carbenos y establecen una correlación entre los desplazamientos de isómeros y las distancias de enlace axial.
Área de la Ciencia:
- Química organometálica
- Química de coordinación
- Espectroscopia
Sus antecedentes:
- Los complejos de porfirina de hierro son cruciales en varios procesos químicos y biológicos.
- Comprender la estructura electrónica y la unión en estos complejos es clave para su reactividad.
- Los ligandos de carbenos ofrecen interacciones de enlace únicas con los centros metálicos.
Objetivo del estudio:
- Sintetizar y caracterizar los nuevos complejos de porfirina de hierro de cinco coordenadas.
- Para aclarar la configuración electrónica y el estado de oxidación del centro de hierro.
- Investigar la naturaleza del enlace metal-carbeno y sus implicaciones estructurales.
Principales métodos:
- Difracción de rayos X de cristal único para la determinación estructural.
- Espectroscopia de absorción de rayos X cerca del borde (XANES) para determinar el estado de oxidación del hierro.
- Espectroscopia de Mössbauer (temperatura múltiple, campo magnético alto) para sondear la configuración electrónica y el enlace.
- La resonancia magnética nuclear (RMN) y la espectroscopia UV-vis para la caracterización complementaria.
Principales resultados:
- El hierro sintetizado es un complejo de porfirinos carbenos con ligandos CCl2 y CPh2.
- XANES confirmó el estado de oxidación del hierro.
- La espectroscopia de Mössbauer reveló una configuración electrónica de bajo espín (S = 0) con grandes divisiones cuádruples.
- Los datos estructurales y de Mössbauer indicaron un carácter covalente para el enlace hierro-carbeno.
- Se estableció una nueva correlación entre los desplazamientos de isómeros de hierro y las distancias de enlace axial para los ligandos de carbenos.
Conclusiones:
- Los complejos de porfirina de carbenos de hierro investigados existen como especies de hierro de baja espina.
- Los ligandos de carbenos forman enlaces covalentes con el centro de hierro, influyendo en la estructura electrónica.
- Se ha identificado una nueva relación estructura-propiedad relacionada con los desplazamientos isoméricos y las distancias de enlace en los complejos hierro-carbeno.
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