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Un nuevo ligando ONO3- trianiónico tipo pinza para generar enlaces múltiples metal-carbono altamente nucleófilos
Matthew E O'Reilly1, Ion Ghiviriga, Khalil A Abboud
1Department of Chemistry, Center for Catalysis, University of Florida, P.O. Box 117200, Gainesville, Florida 32611, USA.
Journal of the American Chemical Society
|June 12, 2012
Resumen
Los investigadores sintetizaron nuevos complejos de tungsteno que imitan la nucleofilicidad de las enaminas. Estos complejos exhiben una reactividad única con los electrófilos, lo que permite nuevas vías sintéticas en la química organometálica.
Área de la Ciencia:
- Química organometálica Química orgánica de los metales.
- Química sintética de la química sintética.
Sus antecedentes:
- Las enaminas son intermedios cruciales en la síntesis orgánica debido a su mayor nucleofilicidad.
- La imitación de la reactividad de las enaminas dentro de una esfera de coordinación metálica ofrece nuevas vías para las transformaciones catalíticas.
Objetivo del estudio:
- Diseñar y sintetizar nuevos ligandos trianiónicos tipo pinza que imiten las enaminas.
- Desarrollar estrategias sintéticas para los complejos de tungsteno-alquilideno y -alquilideno con estos ligandos.
- Caracterizar las propiedades electrónicas y estructurales de estos nuevos complejos de tungsteno.
Principales métodos:
- Síntesis de complejos de tungsteno-alquilideno y -alquilidino con un nuevo ligando CF(3) -ONO(3-).
- Caracterización mediante espectroscopia de RMN multinuclear, análisis de combustión y difracción de rayos X de un solo cristal.
- Estudios computacionales que utilizan la Teoría Funcional de Densidad (DFT) para comprender el enlace y la reactividad.
Principales resultados:
- Síntesis y caracterización exitosas de los complejos de tungsteno-alquilideno [CF(3) -ONO]WCH(Et) ((O(t) Bu) y -alquilidino {MePPh(3)}{[CF(3) -ONO]WC(Et) ((O(t) Bu).
- Se demostró una reactividad nucleofílica única del complejo de alquilidina con electrófilos, lo que lleva a nuevas especies de tungsteno-alquilidina.
- La catálisis del ácido de Lewis en el complejo de tungsteno-alquilideno dio como resultado la expulsión de isobutileno y la formación de un complejo de tungsteno-oxo.
Conclusiones:
- El nuevo ligando CF(3)-ONO(3-) imita efectivamente el comportamiento de las enaminas en los complejos de tungsteno.
- Estos complejos ofrecen una plataforma versátil para explorar nuevas reacciones organometálicas y procesos catalíticos.
- El estudio proporciona información fundamental sobre la interacción entre el diseño del ligando y la reactividad del centro del metal.
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