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Estudios mecánicos de la deshidrogenación del amoniaco borano catalizado por complejos de pinzas de hierro
Papri Bhattacharya1, Jeanette A Krause, Hairong Guan
1Department of Chemistry, University of Cincinnati , P.O. Box 210172, Cincinnati, Ohio 45221-0172, United States.
Journal of the American Chemical Society
|July 19, 2014
Resumen
Los complejos de pinzas de hierro catalizan eficientemente la deshidrogenación del amoniaco borano, liberando gas hidrógeno. El complejo 3 muestra la actividad más alta, con una escisión simultánea de los enlaces B-H y N-H en la etapa de determinación de la tasa.
Área de la Ciencia:
- Química organometálica Química orgánica de los metales.
- La catálisis de la catálisis.
- Almacenamiento de hidrógeno almacenamiento de hidrógeno.
Sus antecedentes:
- El amoniaco borano (AB) es un material de almacenamiento de hidrógeno prometedor.
- La deshidrogenación catalítica eficiente de AB es crucial para la liberación de hidrógeno.
- Los complejos de hierro ofrecen una alternativa rentable a los catalizadores de metales preciosos.
Objetivo del estudio:
- Para sintetizar y evaluar nuevos complejos de pinzas de hierro bis (((fosfinita) para la deshidrogenación de amoniaco borano.
- Para investigar la actividad catalítica y el mecanismo de estos complejos de hierro.
- Para identificar el catalizador más activo y aclarar el paso que determina la velocidad.
Principales métodos:
- Síntesis de complejos de pinzas de hierro bis (((fosfinita).
- Deshidrogenación catalítica del amoniaco borano a 60 °C.
- Estudios cinéticos que incluyen mediciones del efecto isotópico cinético (KIE).
- Espectroscopia de Resonancia Magnética Nuclear (RMN) para la investigación mecanicista.
Principales resultados:
- Los complejos 1-3 catalizan la deshidrogenación AB, liberando 2,3-2,5 equiv de H2 por AB en 24 horas.
- El complejo de hierro 3 demostró la mayor actividad catalítica.
- Los estudios cinéticos revelaron una dependencia de primer orden en el catalizador 3 y de orden cero en AB.
- El análisis de KIE indicó una escisión simultánea de bonos B-H y N-H en la etapa de determinación de la tasa.
Conclusiones:
- Los complejos de pinzas de hierro bis (((fosfinita) son catalizadores efectivos para la deshidrogenación del amoniaco borano.
- El complejo 3 es el catalizador más activo entre los estudiados.
- El mecanismo catalítico implica la escisión simultánea de los enlaces B-H y N-H, con coordinación AB al centro del hierro.
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