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Observación de un complejo σ-alcano de tungsteno que muestra la unión selectiva de grupos metilo utilizando
Rowan D Young1, Douglas J Lawes, Anthony F Hill
1Research School of Chemistry, Australian National University, Canberra ACT, Australia.
Journal of the American Chemical Society
|March 14, 2012
Resumen
Los investigadores sintetizaron un nuevo complejo de tungsteno-alcano, (HEB) W (((CO) 2 ((pentano), utilizando la fotólisis UV. Este estudio presenta los primeros datos de RMN para un complejo de alcano del grupo 6, detallando las preferencias de unión al pentano.
Área de la Ciencia:
- Química organometálica de las sustancias orgánicas.
- La fotoquímica es la fotoquímica.
- La espectroscopia es una técnica de espectroscopia.
Sus antecedentes:
- Los complejos de carbonilo de tungsteno son precursores versátiles en la síntesis organometálica.
- Los σ-complejos de alcanos son importantes intermediarios en las reacciones de activación C-H.
- Estudios previos sobre fragmentos de renio mostraron una unión preferente a grupos de metileno en los ligandos de alcano.
Objetivo del estudio:
- Para sintetizar y caracterizar un nuevo grupo 6 alcano σ-complejo.
- Para investigar el modo de unión del pentano en un complejo de tungsteno-alcano.
- Para comparar las preferencias de unión del pentano en el tungsteno frente a los complejos de renio.
Principales métodos:
- Fotólisis UV de (HEB) W(CO) 3 en disolventes de alcanos a baja temperatura.
- Espectroscopia de infrarrojos (IR). espectroscopía de infrarrojos (IR). espectroscopía de infrarrojos (IR). espectroscopía de infrarrojos (IR). espectroscopía de infrarrojos (IR). espectroscopía de infrarrojos (IR). espectroscopía de infrarrojos (IR). espectroscopía de infrarrojos (IR).
- Espectroscopia de resonancia magnética nuclear (RMN) de protones (1H) y carbono-13 (13C). espectroscopia de resonancia magnética nuclear (RMN) de protones (1H) y carbono-13 (13C). espectroscopia de resonancia magnética nuclear (RMN) de protones (1H) y carbono-13 (13C). espectroscopia de resonancia magnética nuclear (RMN) de protones (1H) y de carbono-13 (13C). espectroscopia de resonancia magnética nuclear (RMN) de protones (1H) y de carbono-13 (13C). espectroscopia de resonancia magnética nuclear (RMN) de protones (1H) y de carbono-13 (13C).
Principales resultados:
- El complejo σ-alcano (HEB) W ((CO) 2 ((pentano) fue producido con éxito.
- Esto representa los primeros datos de RMN reportados para un complejo de alcano del grupo 6.
- Los datos espectroscópicos revelaron la unión exclusiva de la funcionalidad metilo del ligando pentano al centro de tungsteno.
- Esto contrasta con los complejos de renio, que muestran la unión a ambos grupos metilo y metileno.
Conclusiones:
- El complejo de tungsteno-pentano exhibe una clara preferencia de unión para el grupo metilo, a diferencia de sus análogos de renio.
- Los factores estéricos, específicamente la conformación de gauche desfavorable requerida para la unión al metileno, contribuyen a esta preferencia observada.
- Este hallazgo proporciona información sobre los factores que rigen la activación y la funcionalización de los enlaces C-H por los complejos de metales de transición.
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