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trans-W ((Cmesityl) ((dmpe) 2H: revelando un enlace W-H altamente polar y movilidad H en estado líquido y sólido
Fenglou Zou1, Franck Furno, Thomas Fox
1Anorganisch-chemisches Institut, Universität Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland.
Journal of the American Chemical Society
|May 15, 2007
Resumen
Se sintetizaron y estudiaron nuevos complejos de tungsteno para procesos de intercambio dinámico. Se encontró que el enlace W-D en un complejo era 85% iónico, con intercambios dinámicos observados en soluciones y estados sólidos.
Área de la Ciencia:
- Química organometálica Química orgánica de los metales.
- Química del estado sólido.
- Dinámica de las reacciones de reacción.
Sus antecedentes:
- Los complejos de tungsteno con ligandos voluminosos son de interés para la catálisis y la ciencia de los materiales.
- Comprender los procesos dinámicos en los compuestos organometálicos es crucial para predecir la reactividad.
- El etiquetado isotópico proporciona una poderosa herramienta para elucidar los mecanismos de reacción.
Objetivo del estudio:
- Para sintetizar y caracterizar nuevos complejos de tungsteno isotopoméricos.
- Investigar los procesos de intercambio dinámico en soluciones y estados sólidos.
- Para determinar la ionicidad del enlace tungsteno-deuterio.
Principales métodos:
- Síntesis de complejos de tungsteno isotopoméricos.
- Espectroscopia de resonancia magnética nuclear (RMN) con etiquetado de deuterio.
- Estudios de difracción de rayos X. Estudios de difracción de rayos X.
- Diseminación de neutrones casi elástica (QENS).
Principales resultados:
- Se prepararon los complejos trans-W ((Cmesityl) ((C ((H,D) 3) 2PCH2CH2P ((C ((H,D) 3) 2) 2 ((H,D) 1-4 fueron preparados.
- El enlace W-D en el complejo 2 exhibe un 85% de ionicidad, con una constante de acoplamiento cuádrupolo de deuterio (DQCC) de 34.1 kHz.
- El Complejo 1 mostraba procesos de intercambio dinámico que incluían HW/HW, HW/ortho-Mesityl, y HW/H2 en solución, y HW/Mep en estado sólido.
- La isomerización del complejo 1 a un complejo de carbina 5 se observó a 60°C.
- QENS proporcionó una barrera de activación de 5 kcal/mol para el intercambio HW/Mep en estado sólido.
Conclusiones:
- Los procesos de intercambio dinámico influyen significativamente en el comportamiento de estos complejos de tungsteno en soluciones y estados sólidos.
- El enlace W-D posee un alto grado de carácter iónico.
- Se obtuvieron conocimientos mecanicistas detallados sobre las vías de isomerización e intercambio a través de técnicas combinadas de espectroscopia y dispersión.
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