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Reactividad distinta de una especie de peroxocobalto mononuclear hacia la activación de nitrilos

Hyeonju Noh¹, Donghyun Jeong¹, Takehiro Ohta²

¹Department of Emerging Materials Science, DGIST , Daegu 42988, Korea.

Journal of the American Chemical Society

|August 1, 2017

Resumen

Un nuevo complejo de cobalto (III) activa los nitriles utilizando su grupo peroxo, formando complejos de hidroximatocobalto (III). Esta eficiente reacción similar a la dioxigenasa expande la química de utilización del nitrilo en condiciones suaves.

Área de la Ciencia:

Química inorgánica
Química organometálica
Catálisis

Sus antecedentes:

Los complejos de peroxocobalto (III) son conocidos por su actividad catalítica.
La activación del nitrilo es una transformación clave en la síntesis orgánica.
El desarrollo de métodos eficientes y suaves para la funcionalización del nitrilo sigue siendo un objetivo importante.

Objetivo del estudio:

Investigar la reactividad similar a la dioxigenasa de un complejo mononuclear de peroxocobalto (III) con nitriles.
Síntesis y caracterización de nuevos complejos de hidroximatocobalto.
Para aclarar el mecanismo de activación del nitrilo por el complejo de cobalto.

Principales métodos:

Síntesis de un complejo mononuclear de peroxocobalto (III) en el lado ([CoIII (TBDAP) (O2) ]+).
Reacción del complejo de cobalto con varios nitriles (R-CN) en condiciones ambientales.
Caracterización de productos mediante técnicas de cristalografía y espectroscopia de rayos X (por ejemplo, RMN, IR).
Estudios mecanicistas que incluyen experimentos de etiquetado de 18O y análisis cinético (efectos de isótopos de Hammett).

Principales resultados:

El complejo de cobalto (CoIII ((TBDAP) ((O2)) +) reacciona eficientemente con los nitriles para formar complejos mononucleares de hidroximatocobalto ((III)) (CoIII ((TBDAP) ((R-C ((NO) O)) +).
La reacción se lleva a cabo en una sola olla en condiciones suaves (40 °C, ~ 1 hora).
El etiquetado con 18O confirmó que ambos átomos de oxígeno en el producto proceden del ligando peroxo.
La cristalografía y la espectroscopia de rayos X verificaron las estructuras de los productos de hidroximatocobalto.
Los estudios cinéticos sugieren un mecanismo concertado para la activación del nitrilo.

Conclusiones:

Se ha demostrado una nueva y fácil reactividad de un complejo de peroxocobalto (III) hacia los nitriles.
Esta reacción proporciona un valioso nuevo método para la activación y la funcionalización del nitrilo.
Los hallazgos contribuyen a la expansión de las metodologías sintéticas en química organometálica y catálisis.

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