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Investigación mecánica de la hidrogenación de O(2) por un catalizador de hidrogenación por transferencia
Sugata Chowdhury1, Fahmi Himo, Nino Russo
1Dipartimento di Chimica, Università della Calabria, I-87030, Arcavacata di Rende, Italy.
Journal of the American Chemical Society
|March 12, 2010
Resumen
Este estudio investiga la hidrogenación del oxígeno molecular utilizando cálculos funcionales de densidad híbrida. Revela que el paso lento es la inserción de O2 en el enlace Ir-H, con condiciones ácidas que mejoran la energía de este ciclo catalítico.
Área de la Ciencia:
- Química organometálica Química orgánica de los metales.
- Química computacional es la química computacional.
- La catálisis es la catálisis.
Sus antecedentes:
- La hidrogenación catalítica del oxígeno molecular es crucial para varios procesos químicos.
- Los complejos de iridio, como Cp*IrH(TsDPEN) (1H(H)), son catalizadores conocidos para esta reacción.
- Comprender el mecanismo de reacción es clave para optimizar la eficiencia catalítica.
Objetivo del estudio:
- Para dilucidar los detalles mecanicistas de la hidrogenación de oxígeno molecular catalizada por Cp*IrH(TsDPEN).
- Para explorar el ciclo catalítico utilizando cálculos funcionales de densidad híbrida.
- Para investigar la influencia de las condiciones ácidas en la vía de reacción y la energía.
Principales métodos:
- Se emplearon cálculos funcionales de densidad híbrida (B3LYP) para estudiar las superficies de energía potencial.
- Se analizó el proceso de hidrogenación del catalizador (1) y su correspondiente catión amina de iridio ([1H] (+))
- Se realizó un análisis computacional para identificar el paso determinante de la tasa y los intermedios.
Principales resultados:
- La adición de H(2) a los complejos de diamido (1) es favorable pero lenta, acelerada por los ácidos de Bronsted.
- La reducción de O2 procede a través de un intermediario de iridio hidroperoxo, con la inserción de O2 en el enlace Ir-H como paso lento.
- Las condiciones ácidas mejoran la energía de reacción, pasando por el intermedio H(2) O(2) y regenerando el catalizador protonado [1H](+).
Conclusiones:
- Los hallazgos computacionales se alinean con las observaciones experimentales con respecto a la cinética de la reacción y los intermedios.
- El estudio identifica la inserción de O2 en el enlace Ir-H como el paso que limita la velocidad en el ciclo catalítico.
- Las condiciones ácidas ofrecen una vía energéticamente más favorable para la hidrogenación del oxígeno molecular.
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