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Principios de diseño de catalizadores que permiten las reacciones de cicloadición y despolimerización de

Megan Mohadjer Beromi¹, Jarod M Younker², Hongyu Zhong¹

¹Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States.

Journal of the American Chemical Society

|October 15, 2021

Resumen

Los catalizadores de hierro y rutenio facilitan las cicloadiciones de alqueno y dieno, formando vinilciclobutanos reciclables. Diseño del catalizador, en particular el ligando de la pinza

Área de la Ciencia:

Química organometálica
Catálisis
Ciencia de los Polímeros

Sus antecedentes:

Los complejos de hierro piridina ((diimina) catalizan [2+2] cicloadiciones de alquenos y dienos, dando lugar a los vinilciclobutanos.
Estas reacciones también permiten la oligomerización del butadieno a divinyl (oligociclobutano), una microestructura de polímero reciclable.

Objetivo del estudio:

Investigar los mecanismos catalíticos de los complejos de hierro y rutenio de piridina ((diimina) sustituida por arilo en las reacciones de cicloadición y oligomerización.
Aclarar las relaciones estructura-actividad para diseñar catalizadores avanzados y promover el reciclaje químico de polímeros.

Principales métodos:

Estudio sistemático de los complejos de hierro y butadieno de rutenio.
Análisis estructural y computacional de los complejos de hierro butadieno.
Experimentos de etiquetado y estudios mecanicistas.

Principales resultados:

La rigidez del catalizador promueve la coordinación s-transdieno, lo que facilita la ciclización oxidativa.
La formación de ciclobutano se produce a través de un intermediario metalicíclico con acoplamiento reductor reversible C ((sp3) -C ((sp3).
Los complejos de hierro utilizan un mecanismo de cruce de espín (S = 0 a S = 1) para la eliminación reductiva de C ((sp3) - C ((sp3)) en condiciones térmicas.
Los complejos de rutenio requieren irradiación de luz azul para una reactividad similar, con un ligando de piridina (diimina) inocente de redox.

Conclusiones:

Las características estructurales de los catalizadores de hierro de piridina (diimina) son cruciales para la coordinación de dieno y la posterior cicloadición.
Los catalizadores de hierro permiten la formación de enlaces C ((sp3) - C ((sp3)) impulsados térmicamente a través del cruce de espín.
Los catalizadores de rutenio ofrecen reactividad impulsada por la luz, destacando distintas vías de activación.
La comprensión de estos mecanismos proporciona principios de diseño para los catalizadores de próxima generación y el reciclaje químico de polímeros.

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