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Contribuciones orbitales moleculares de frontera a la selectividad de la cloración frente a la hidroxilación en la
Martin Srnec1, Edward I Solomon2
1J. Heyrovský Institute of Physical Chemistry, The Czech Academy of Sciences , Dolejškova 2155/3, 182 23 Prague 8, Czech Republic.
Journal of the American Chemical Society
|January 19, 2017
Resumen
Los estudios computacionales revelan que el intermediario de hierro en SyrB2 puede realizar tanto la cloración como la hidroxilación. La cloración es intrínsecamente más reactiva, mientras que la selectividad depende de la orientación del sustrato y de factores electrónicos.
Área de la Ciencia:
- La bioquímica
- Química computacional
- Enzimología
Sus antecedentes:
- SyrB2 es una enzima que contiene un intermediario de hierro ((IV) - oxo (FeIVO).
- Comprender la reactividad de este intermediario es crucial para la función de la enzima.
Objetivo del estudio:
- Evaluación computacional de la capacidad de cloración frente a la capacidad de hidroxilación del intermedio FeIVO en SyrB2.
- Aclarar los factores que rigen la selectividad entre la cloración y la hidroxilación.
Principales métodos:
- Se emplearon cálculos de la Teoría Funcional de la Densidad (DFT).
- Análisis de las trayectorias de reacción y las estructuras electrónicas.
Principales resultados:
- Se identificó un complejo HO-Fe (III) -Cl de cinco coordenadas como un intermediario clave.
- La hidroxilación es termodinámicamente favorecida, pero la cloración exhibe una mayor reactividad intrínseca debido a la división de energía de la órbita molecular de frontera (FMO).
- La selectividad está influenciada por la orientación del sustrato y la superposición π con el radical del sustrato.
Conclusiones:
- La reactividad intrínseca de la cloración compite efectivamente con la hidroxilación.
- El mecanismo de reacción implica la transferencia asíncrona de electrones y ligandos.
- La orientación del sustrato dicta la selectividad final entre la cloración y la hidroxilación.
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