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Un estudio funcional de densidad de la escisión de enlaces O-O para un complejo biomimético de hierro no hemo que

Arianna Bassan¹, Margareta R A Blomberg, Per E M Siegbahn

¹Contribution from the Department of Physics, Stockholm Center for Physics, Astronomy and Biotechnology, Stockholm University, S-106 91, Stockholm, Sweden. arianna@physto.se

Journal of the American Chemical Society

|September 13, 2002

Resumen

Los complejos de hierro con los ligandos tris ((2-piridilmetil) amina) catalizan la oxidación de los hidrocarburos. Los cálculos de DFT revelan la formación de Fe ((V) = O a través de la heterólisis O-O con H ((2) O ((2), preservando la estereospecificidad.

Área de la Ciencia:

Química organometálica Química orgánica de los metales.
Química computacional es la química computacional.
La catálisis por catálisis.

Sus antecedentes:

Los complejos de hierro con los ligandos tris ((2-piridilmetil) amina) (TPA) son catalizadores conocidos para la oxidación estereospecífica de hidrocarburos.
El peróxido de hidrógeno (H2O2) es un oxidante común en estos sistemas catalíticos.

Objetivo del estudio:

Para investigar el mecanismo de reacción de los complejos Fe ((TPA) durante la oxidación de hidrocarburos utilizando H ((2) O ((2)).
Para explorar las vías de escisión de enlaces O-O en intermedios catalíticos.

Principales métodos:

Cálculos de la Teoría Funcional de Densidad (DFT) utilizando el funcional híbrido B3LYP.
Investigación de las vías de reacción y estados de transición para la escisión de enlaces O-O.

Principales resultados:

Se forma un intermediario de hierro-oxo de alta valencia (Fe(V) = O) a través de la heterólisis de enlaces O-O, consistente con los datos experimentales.
A diferencia de los intermediarios P450, el ligando TPA permanece sin oxidar, con la extracción de electrones principalmente desde el centro de hierro.
La escisión del enlace homolítico O-O es energéticamente inaccesible para H(2) O(2), lo que garantiza la estereospecificidad de la reacción.
Para los oxidantes de alquilperóxido, la homólisis O-O tiene una barrera más baja, lo que lleva a la pérdida de estereospecificidad.

Conclusiones:

El sistema Fe ((TPA) logra una oxidación estereospecífica a través de la formación de Fe ((V) = O a través de la escisión heterolítica O-O con H ((2) O ((2)).
La mayor fuerza de enlace O-O en H(2) O(2) en comparación con los alquilperóxidos dicta la vía de escisión y la estereospecificidad.

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