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Caracterización estructural y espectroscópica de un complejo Fe (VI) bis (imido)
Jorge L Martinez1, Sean A Lutz1, Hao Yang2
1Department of Chemistry, Indiana University, Bloomington, IN 47405, USA.
Science (New York, N.Y.)
|October 16, 2020
Resumen
Los investigadores sintetizaron un complejo de hierro hexavalente estable, un estado de oxidación raro. Este compuesto Fe ((VI), con una geometría de columpio única, se caracterizó utilizando métodos espectroscópicos y estructurales avanzados.
Área de la Ciencia:
- Química inorgánica
- Química bioorgánica
- Química de coordinación
Sus antecedentes:
- Las especies de hierro de alta valencia son cruciales en las reacciones de oxidación biológica.
- Los complejos hexavalentes de hierro, excluyendo el ferrato, son excepcionalmente poco comunes en química.
- Comprender estas especies proporciona una visión de los mecanismos biológicos oxidativos.
Objetivo del estudio:
- Sintetizar y caracterizar un complejo de hierro hexavalente estable.
- Investigar las propiedades estructurales y electrónicas de los complejos Fe (V) y Fe (VI) bis (imido).
- Para aclarar los factores que rigen la geometría única observada en estos complejos de hierro.
Principales métodos:
- Síntesis de complejos Fe (V) y Fe (VI) bis (imido) mediante oxidación de un electrón.
- Difracción de rayos X de un solo cristal para la determinación estructural.
- Fe Mössbauer, espectroscopia de fotoelectrones de rayos X (XPS), espectroscopia de absorción de rayos X (XAS) y doble resonancia electron-nuclear (ENDOR) para la caracterización electrónica.
- Cálculos computacionales de la estructura electrónica.
Principales resultados:
- Se sintetizó con éxito un complejo Fe (VI) estable a partir de un precursor Fe (V) (2).
- Ambos complejos Fe (V) y Fe (VI) exhiben un raro centro de hierro de cuatro coordenadas con una geometría distintiva de "roscador".
- Los datos y cálculos espectroscópicos confirman una configuración de FeV de bajo espín (S=1/2) en 2 y una configuración de FeVI diamagnética (S=0) en 3.
- La geometría de columpio observada se atribuye a la interacción de las interacciones de enlace Fe-imido sigma y pi.
Conclusiones:
- Se pueden preparar complejos estables de Fe (VI) mediante la oxidación controlada de precursores de hierro de menor valor.
- La geometría "de columpio" es un motivo estructural recurrente en estos complejos de hierro bis (imido), dictado por factores electrónicos.
- Este trabajo amplía la química conocida del hierro de alta valencia, ofreciendo información sobre su estructura electrónica y unión.
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