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Equilibrar las especies (L) Fe^III-OOAc y (L) Fe^V(O) en las oxidaciones de hidrocarburos mediante catalizadores de

Williamson N Oloo¹, Rahul Banerjee², John D Lipscomb²

¹Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota , Minneapolis, Minnesota 55455, United States.

Journal of the American Chemical Society

|November 15, 2017

Resumen

Los catalizadores de hierro no hemo imitan las oxigenasas de Rieske para la oxidación de hidrocarburos. Una especie Fe ((V) ((O) ((OAc), no Fe ((III) -OOAc, es el oxidante activo, que ofrece ideas para el diseño del catalizador.

Área de la Ciencia:

Química bioorgánica
Catálisis
Química orgánica

Sus antecedentes:

Las enzimas Rieske oxigenasa son cruciales para la oxidación de hidrocarburos.
Los complejos de hierro no hemo con ligandos N4 se exploran como catalizadores biomiméticos.
Los ácidos carboxílicos modulan la selectividad en estas reacciones de oxidación.

Objetivo del estudio:

Desarrollar catalizadores de hierro no hemo para la oxidación de hidrocarburos utilizando H2O2.
Elucidar las especies oxidantes activas y el mecanismo de reacción.
Comprender cómo las propiedades de los ligandos influyen en la selectividad catalítica.

Principales métodos:

Síntesis de complejos de hierro no hemo con ligandos N4 tetradentados.
Reacciones de oxidación de hidrocarburos utilizando H2O2 y ácidos carboxílicos.
Espectroscopia de resonancia paramagnética de electrones (EPR) para la identificación de los productos intermedios.
Estudios cinéticos y simulaciones numéricas para modelar las vías de reacción.

Principales resultados:

Se observaron dos compuestos intermedios S=1/2 a través de la EPR: un g2,7 (Fe(III) -OOAc) y un g2,07 (Fe(V) ((O) ((OAc)).
La especie g2.07 fue identificada como el oxidante activo responsable de la oxidación del sustrato.
La especie g2.7 actúa como un reservorio fuera de la vía para la especie g2.07 activa.
La selectividad del catalizador está modulada por las propiedades electrónicas y estéricas de los ácidos carboxílicos y los ligandos de soporte.

Conclusiones:

La especie Fe (V) (O) (OAc) es el oxidante clave en estas reacciones catalizadas por hierro no hemo.
La comprensión de estos intermedios ayuda a diseñar catalizadores de oxidación más eficientes y selectivos.
Este trabajo proporciona conocimientos mecanicistas sobre las enzimas oxigenasas naturales.

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