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Influencia de la esfera de coordinación secundaria en la reactividad de los complejos de hierro no hemo (II): un
Sumit Sahu1, Leland R Widger, Matthew G Quesne
1Department of Chemistry, The Johns Hopkins University, 3400 North Charles Street, Baltimore, Maryland 21218, USA.
Journal of the American Chemical Society
|July 10, 2013
Resumen
Nuevos complejos de hierro con ligandos biomiméticos muestran que la estructura del ligando controla la reactividad. Los sustituyentes controlados permiten una rápida hidroxilación del areno, mientras que los grupos de amida estabilizan los intermedios, evitando esta reacción.
Área de la Ciencia:
- Química bioorgánica Química bioorgánica.
- Química organometálica Química orgánica de los metales.
- La catálisis es la catálisis.
Sus antecedentes:
- Las enzimas de hierro no hemo juegan un papel crucial en las reacciones de oxidación biológica.
- Comprender los mecanismos de estas enzimas es clave para desarrollar catalizadores sintéticos.
- El diseño de los ligandos influye significativamente en la reactividad y estabilidad de los complejos de hierro.
Objetivo del estudio:
- Para sintetizar y caracterizar nuevos complejos biomiméticos de hierro con entornos de ligando a medida.
- Para investigar el impacto de los sustituyentes de ligando en el estado de espín y la reactividad de los centros de hierro.
- Explorar el papel de las interacciones de la esfera de coordinación secundaria en las reacciones de oxidación catalítica.
Principales métodos:
- Síntesis de nuevos ligandos N4Py (((2Ph) y N4Py (((2Ph,amida).
- Formación y caracterización de los complejos de hierro (II).
- Análisis espectroscópico y estructural para determinar el entorno de coordinación y las propiedades electrónicas.
- Estudios mecanicistas para sondear las vías de reacción, incluidos los cambios de estado de espín y la formación de intermedios.
Principales resultados:
- Se sintetizaron con éxito dos nuevos complejos de hierro (II), [Fe (II) ] (N4Py (Ph) 2 (NCCH3) ] (BF4) 2 y [Fe (II) ] (N4Py (Ph) 2 (amida)) (BF4) 2.
- La orientación controlada del sustituto del fenilo en el primer complejo facilitó la reactividad de espín triplet para un intermediario Fe ((IV) ((O), lo que condujo a una hidroxilación eficiente del areno.
- La incorporación de un grupo de amida cerca del centro del hierro estabilizó una especie Fe ((III) OOR de alto espín, que no dio lugar a la hidroxilación del areno.
Conclusiones:
- Las interacciones de la esfera de coordinación secundaria, como el enlace de hidrógeno de los grupos amídicos, influyen profundamente en la reactividad de los centros de hierro no hemo.
- El diseño de los ligandos es crítico para controlar las transiciones de estado de espín y dirigir el resultado de las reacciones de oxidación.
- Estos hallazgos ofrecen información valiosa para el desarrollo de catalizadores biomiméticos selectivos y eficientes.
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