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Acoplamiento cruzado de carbodicarbeno basado en NHC / CAAC: síntesis de diradicaloides con deficiencia de electrones

Vasu Malhotra¹, Benedict J Elvers², Ramapada Dolai¹

¹Tata Institute of Fundamental Research Hyderabad, Gopanpally, Hyderabad 500046, India.

Journal of the American Chemical Society

|October 19, 2024

Resumen

Las reacciones de acoplamiento cruzado catalizadas por níquel (0) permiten la síntesis de nuevos diradicaloides a partir de carbodicarbenos y haluros de arilo. Este enfoque modular permite ajustar las propiedades electrónicas y explorar las vías de dimerización radical-radical.

Área de la Ciencia:

Química organometálica
Química de los carbenos
Ciencias de los materiales

Sus antecedentes:

Los carbodicarbenos, equivalentes atómicos de carbono estabilizados por el donante, se informaron por primera vez en 2007.
La exploración de nuevas estructuras diradicaloides es crucial para comprender la deslocalización de electrones y los estados de espín.

Objetivo del estudio:

Desarrollar una metodología sintética modular para los diradicaloides con deficiencia de electrones.
Investigar las reacciones de acoplamiento de carbenos N-heterocíclicos (NHC) y carbenos cíclicos (alquilo-amino) (CAAC) con haluros de arilo.
Estudiar las propiedades electrónicas y la dimerización radical-radical de los derivados diradicaloides resultantes.

Principales métodos:

Reacciones de acoplamiento cruzado catalizadas por níquel de carbodicarbeno con cloruros de arilo, bromuros y yoduros.
Oxidación de un electrón de derivados de carbodicarbeno sustituidos por arilo a dications radicales.
Síntesis de diradicaloides puenteados conjugados con π utilizando vinculantes de fenileno y bifenileno.

Principales resultados:

Acoplamiento cruzado exitoso de carbodicarbenos con varios haluros de arilo.
Formación de derivados catiónicos de carbodicarbeno sustituidos por arilo y su subsiguiente oxidación a dications radicales.
Demostración de diferentes modos de dimerización radical-radical y síntesis de diradicaloides centrados en el carbono/nitrógeno, el nitrógeno/nitrógeno y el carbono/carbono.
El espaciador π-conjugado influye significativamente en la población de tripletes a temperatura ambiente mediante la modulación de la brecha singleta-tripleta.

Conclusiones:

Se ha establecido una metodología modular para sintetizar diversos diradicaloides con deficiencia de electrones.
La estrategia de acoplamiento cruzado proporciona acceso a nuevas estructuras diradicaloides con propiedades electrónicas sintonizables.
El estudio pone de relieve la importancia del espaciador conjugado π en el control de los estados de espín y abre caminos para el diseño de nuevos materiales.

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