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Aislamiento de un hidruro de diirón de valencia mixta: evidencia de un hidruro espectador en la catálisis de la
Wenguang Wang1, Mark J Nilges, Thomas B Rauchfuss
1School of Chemical Sciences, University of Illinois, Urbana, Illinois 61801, United States.
Journal of the American Chemical Society
|February 7, 2013
Resumen
Este estudio detalla un complejo hidrídido de diirón de valencia mixta, revelando su estereoquímica y estructura electrónica únicas. El ligando hidruro puente se confirma como un espectador en las reacciones de evolución del hidrógeno.
Área de la Ciencia:
- Química organometálica Química orgánica de los metales.
- Química Inorgánica La Química Inorgánica es la química inorgánica.
- La catálisis es la catálisis.
Sus antecedentes:
- Los complejos de dihidrido de hierro de valencia mixta son cruciales para comprender la transferencia de electrones y los procesos catalíticos.
- La estereoquímica y la estructura electrónica de tales complejos dictan su reactividad, particularmente en la evolución del hidrógeno.
Objetivo del estudio:
- Para caracterizar el complejo de dihidrido de hierro de valencia mixta (μ-H) Fe2 ((pdt) ((CO) 2 ((dppv) 2 ([H1] ((0)) generado por reducción.
- Para dilucidar las propiedades estereoquímicas y electrónicas de [H1](0) y sus isómeros utilizando métodos cristalográficos y espectroscópicos.
- Para investigar el papel del ligando hidruro puente en las reacciones de evolución del hidrógeno.
Principales métodos:
- Reducción de un precursor de hidruro diferencial utilizando el decametilcobaltoceno.
- Cristalografía de rayos X para la determinación estructural.
- Espectroscopia de resonancia paramagnética de electrones (EPR) de banda X para la identificación de isómeros y el análisis de la estructura electrónica.
- Cálculos de la teoría funcional de la densidad (DFT) para simulación espectral y asignación de acoplamiento hiperfino.
- Estudios de reactividad que involucran protonación y reducción.
Principales resultados:
- El análisis cristalográfico de [H1](0) reveló la retención de la estereoquímica de su precursor, con distintas longitudes de enlace Fe-H.
- La espectroscopia EPR identificó dos estereoisómeros: un isómero mayor no simétrico (unsym) y un isómero menor simétrico (sym).
- Los cálculos de DFT y los datos de EPR confirmaron la localización orbital molecular ocupada individualmente en el centro de Fe con el enlace Fe-H más largo (Fe (II) -H···Fe (I)).
- Se descubrió que el ligando hidruro puente era un espectador durante la evolución del hidrógeno, con protonación que produce H2 y regeneración del complejo oxidado.
Conclusiones:
- El complejo hidrido de diironio de valencia mixta [H1](0) exhibe estereoisómeros distintos con configuraciones electrónicas únicas.
- El ligando hidruro puente juega un papel pasivo en el mecanismo de reacción de la evolución del hidrógeno.
- Este trabajo proporciona información fundamental sobre las relaciones estructura-reactividad de los complejos hidrido de diirón relevantes para la catálisis.
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