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Deshidroacoplamiento catalizado por el hierro / deshidrogenación de aminoboranos catalizados por el hierro
James R Vance1, André Schäfer, Alasdair P M Robertson
1School of Chemistry, University of Bristol, Cantock's Close , Bristol BS8 1TS, U.K.
Journal of the American Chemical Society
|February 18, 2014
Resumen
Los complejos de carbonilo de hierro catalizan de manera eficiente el deshidroacoplamiento amina-borano a los ciclodiborazano. Se observaron diferentes mecanismos para los precatalizadores de hierro 1 y 2, con la formación de nanopartículas que influyen en la actividad catalítica.
Área de la Ciencia:
- Química organometálica Química orgánica de los metales.
- La catálisis es la catálisis.
- Ciencia de los materiales Ciencia de los materiales.
Sus antecedentes:
- Los complejos de carbonilo de hierro están fácilmente disponibles y son precatalizadores versátiles.
- Las aminoboranas son importantes precursores para la síntesis de materiales.
- Las reacciones de deshidroacoplamiento ofrecen una vía a valiosos compuestos cíclicos.
Objetivo del estudio:
- Investigar la eficacia de los complejos de carbonilo de hierro como precatalizadores para el deshidroacoplamiento amina-borano.
- Para aclarar las vías mecanicistas involucradas en el ciclo catalítico.
- Para explorar la naturaleza de las especies catalíticas activas, homogéneas o heterogéneas.
Principales métodos:
- La fotoirradicación UV de amina-borano con precatalizadores de carbonio de hierro.
- In situ (11) B Espectroscopia de RMN para el monitoreo de la reacción.
- Estudios DFT experimentales y computacionales para la investigación mecanicista.
Principales resultados:
- Los complejos carbonilo de hierro [CpFe(CO) ]2 (1) y CpFe(CO) 2I (2) producen eficientemente ciclodiborazano [Me2N-BH2]2 (4) a partir de Me2NH·BH3 (3).
- Se identificaron mecanismos distintos en dos etapas para los precatalizadores 1 y 2, que involucran diferentes intermediarios.
- Un catalizador más activo, Cp2Fe2 ((CO) 3 ((MeCN) (7), formó nanopartículas de hierro (heterogéneas) y no requirió fotoactivación.
- El precatalizador 2 produjo un catalizador activo homogéneo, mientras que el precatalizador 1 probablemente formó nanopartículas heterogéneas bajo fotoirradicación.
Conclusiones:
- Los complejos de carbonilo de hierro sirven como eficaces precatalizadores para el deshidroacoplamiento amina-borano.
- El mecanismo catalítico y la naturaleza de las especies activas (homogéneas o heterogéneas) dependen del precatalizador específico de hierro.
- La formación de nanopartículas de hierro puede mejorar significativamente la actividad catalítica en estas reacciones de deshidroacoplamiento.
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