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Deshidroacoplamiento catalítico homogéneo/deshidrogenación de aductos amina-borano por metales de transición
Matthew E Sloan1, Anne Staubitz, Timothy J Clark
1School of Chemistry, University of Bristol, Bristol, BS8 1TS, United Kingdom.
Journal of the American Chemical Society
|February 26, 2010
Resumen
Los precatalizadores de metaloceno del grupo 4 deshidrolizan de manera eficiente los aductos amino-borano. Los complejos de titanio (II) catalizan esta transformación a través de un mecanismo de dos ciclos, formando dímeros cíclicos a partir de intermedios lineales.
Área de la Ciencia:
- Química organometálica Química orgánica de los metales.
- La catálisis de la catálisis.
- Química del boro y su química.
Sus antecedentes:
- Los aductos de amina-borano son precursores versátiles en la química sintética.
- Se necesitan métodos catalíticos eficientes para su transformación.
- Los complejos de metaloceno ofrecen propiedades catalíticas sintonizables.
Objetivo del estudio:
- Para investigar el deshidroacoplamiento catalítico de aductos de amina-borano utilizando precatalizadores de metaloceno del grupo 4.
- Para dilucidar el mecanismo de reacción e identificar las especies catalíticas activas.
- Para explorar la influencia de la estructura del catalizador en la actividad.
Principales métodos:
- Reacciones de deshidroacoplamiento catalítico utilizando varios aductos de amina-borano y precatalizadores de metaloceno del grupo 4.
- Estudios mecanicistas que implican mediciones del efecto del isótopo cinético y identificación intermedia.
- Modelado computacional para apoyar las vías de reacción propuestas.
Principales resultados:
- Se logró un deshidroacoplamiento catalítico eficiente de los aductos amino-borano con los precatalizadores metaloceno del grupo 4.
- Se identificaron especies de titanio (II) como los catalizadores activos, que operan a través de un mecanismo de dos ciclos y cuatro pasos.
- La actividad catalítica disminuyó en el grupo y con sustitutos de ligando Cp voluminosos / donantes de electrones.
Conclusiones:
- Los metallocenos del grupo 4, en particular los complejos de titanio (II), son catalizadores efectivos para el deshidroacoplamiento amina-borano.
- Se propuso un ciclo catalítico detallado que involucra intermedios de dímeros lineales y cíclicos.
- El diseño de los ligandos impacta significativamente el rendimiento del catalizador en estas transformaciones.
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