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Carbenos heterocíclicos con grupos polifluorados en las posiciones 4 y 5 de [3 + 2] adiciones cíclicas entre

Masato Ohashi¹, Kota Ando², Shoichi Murakami³

¹Department of Chemistry, Graduate School of Science, Osaka Metropolitan University, Sakai 599-8531 Osaka, Japan.

Journal of the American Chemical Society

|September 26, 2023

Resumen

Este estudio introduce nuevos carbenos N-heterocíclicos fluorados (NHC^F) con propiedades electrónicas únicas. Estos NHC fluorados exhiben capacidades mejoradas de aceptación de π, útiles en catálisis y ciencia de materiales.

Área de la Ciencia:

Química organometálica
Química del fluor
Química de los carbenos

Sus antecedentes:

Los carbenos N-heterocíclicos (NHC) son ligandos versátiles en la química organometálica.
La fluoración de moléculas orgánicas puede alterar significativamente sus propiedades electrónicas y estéricas.
El desarrollo de NHC con propiedades electrónicas sintonizables es crucial para el avance de la catálisis.

Objetivo del estudio:

Para sintetizar nuevos carbenos N-heterocíclicos fluorados (NHCF).
Para investigar las propiedades electrónicas de los NHC que llevan átomos de flúor en las posiciones 4 y 5.
Explorar el impacto de los sustituyentes perfluorados en las características del ligando NHC.

Principales métodos:

Síntesis de sales de imidazolio 4,5-difluoradas por medio de la [3 + 2] cicloadición de N,N'-bis(arilo) formamidinatos de sodio con tetrafluoroetileno.
Formación de precursores NHC utilizando compuestos perfluorados como el octafluorociclopenteno y el hexafluorobenzeno.
Caracterización mediante espectroscopia de RMN y análisis de complejos metálicos (Ni, Au) y % de volumen enterrado (%V_bur).

Principales resultados:

Síntesis exitosa de NHC 4,5-difluorados y derivados polifluorados relacionados (CypIPrF y BIPrF).
Los sustituyentes de flúor exhiben un efecto mesomérico donante de electrones, mientras que los anillos perfluorados actúan como aceptores de electrones.
Los NHC F muestran un carácter mejorado de aceptación de π y propiedades electrónicas sintonizables sin cambios estéricos significativos.

Conclusiones:

La fluoración en las posiciones 4 y 5 de los NHC conduce a propiedades electrónicas únicas.
Los anillos fundidos perfluorados imparten fuertes capacidades de aceptación de electrones a los ligandos NHC.
Estos nuevos NHC ofrecen una nueva plataforma para el diseño de catalizadores y materiales avanzados.

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