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Modelado realista de la hidrogenación de transferencia catalizada por rutenio
Jan-Willem Handgraaf1, Evert Jan Meijer
1Van't Hoff Institute for Molecular Sciences, Universiteit van Amsterdam, Nieuwe Achtergracht 166, 1018 WV Amsterdam, The Netherlands. j.w.handgraaf@chem.leidenuniv.nl
Journal of the American Chemical Society
|February 27, 2007
Resumen
Los efectos de los disolventes alteran significativamente los mecanismos de hidrogenación por transferencia catalizada por rutenio. La solución de metanol convierte la transferencia concertada de la fase gaseosa en un proceso secuencial, reduciendo las barreras de activación y revelando una vía mediada por solventes.
Área de la Ciencia:
- Química computacional es la química computacional.
- La catálisis por catálisis.
- Química Física es la química física.
Sus antecedentes:
- La hidrogenación de transferencia catalizada por rutenio es crucial en la síntesis orgánica.
- Comprender los efectos del disolvente es vital para optimizar las reacciones catalíticas.
- Los estudios previos a menudo descuidan el modelado explícito del disolvente.
Objetivo del estudio:
- Para investigar computacionalmente la hidrogenación de transferencia catalizada por rutenio del formaldehído y su reacción inversa.
- Para dilucidar el mecanismo de reacción y la termodinámica en solución de metanol explícito.
- Para comparar los resultados de la fase de solución con los cálculos de la fase gaseosa para cuantificar los efectos del disolvente.
Principales métodos:
- Utilizando la dinámica molecular ab initio (AIMD) para un modelo completamente atomístico.
- Cálculo de la termodinámica, el mecanismo y la estructura electrónica a lo largo de la trayectoria de reacción.
- Realizar comparaciones directas entre las reacciones en fase gaseosa y en la fase de solución.
Principales resultados:
- El perfil energético en solución difiere significativamente de la fase gaseosa.
- Se identifica una barrera de solvación distinta, reduciendo las barreras de activación en ambas direcciones de reacción.
- La transferencia concertada de hidruro y protón en la fase gaseosa se convierte en un mecanismo secuencial en solución, formando un intermediario parecido al metóxido.
Conclusiones:
- El disolvente de metanol explícito juega un papel crítico, alterando el mecanismo de reacción.
- Es factible un mecanismo mediado por disolventes, además del mecanismo bifuncional metal-ligando.
- Este estudio pone de relieve el papel activo de los disolventes en las reacciones catalizadas por metales de transición, ofreciendo nuevos conocimientos mecanicistas.
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