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El análisis espectroscópico de la oxidación catalítica del agua por [Ru(II) ((bpy) ((tpy) H2O]2+ sugiere que Ru(V) O
Yulia Pushkar1, Dooshaye Moonshiram, Vatsal Purohit
1Department of Physics, Purdue University , 525 Northwestern Avenue, West Lafayette, Indiana 47907, United States.
Journal of the American Chemical Society
|August 19, 2014
Resumen
Los catalizadores de rutenio para la división del agua son cruciales. Este estudio muestra que el intermedio activo es principalmente una especie de Ru(IV) -oxo, no el Ru(V) -oxo propuesto anteriormente, desafiando los mecanismos de activación del agua existentes.
Área de la Ciencia:
- La catálisis de la catálisis.
- Química Inorgánica La Química Inorgánica es la química inorgánica.
- La espectroscopia es una técnica de espectroscopia.
Sus antecedentes:
- Mejorar los catalizadores de división del agua es un desafío clave en la química moderna.
- Se necesita una comprensión mecánica detallada de los catalizadores Ru homogéneos de un solo sitio para el progreso.
- El complejo [Ru ((II) ((bpy) ((tpy) H2O)) ((2+) es un sistema modelo bien estudiado para la oxidación del agua.
Objetivo del estudio:
- Para aclarar el verdadero mecanismo catalítico del catalizador de división de agua [Ru(II) ((bpy) ((tpy) H2O] ((2+).
- Para identificar las especies intermedias predominantes de rutenio bajo condiciones catalíticas.
- Reevaluar el papel propuesto del intermediario [Ru(V) ((bpy) ((tpy) O] ((3+).
Principales métodos:
- Espectroscopia combinada de resonancia paramagnética de electrones (EPR) y espectroscopia de absorción de rayos X (XAS).
- Cálculos de la teoría funcional de la densidad (DFT) para evaluar la accesibilidad termodinámica de los intermedios.
- Análisis del comportamiento del precursor del catalizador [Ru(II) ((bpy) ((tpy) Cl] ((+).
Principales resultados:
- La especie de rutenio dominante en el estado estacionario catalítico se identifica como [Ru(IV) ((bpy) ((tpy) O) ((2+) (95%).
- El intermedio propuesto [Ru(V) ((bpy) ((tpy) O] ((3+) no fue detectado y puede ser termodinámicamente inaccesible.
- Se observó una especie menor de Ru(III) -peroxo, y se encontró que el precursor [Ru(II) ((bpy) ((tpy) Cl] ((+) era inactivo sin intercambio de ligandos.
Conclusiones:
- El intermediario activo en esta división de agua catalizada por Ru es predominantemente una especie de Ru (IV) -oxo, no Ru (V) -oxo.
- Este hallazgo requiere una revisión del mecanismo catalítico propuesto para esta clase de catalizadores.
- El diseño de los ligandos, particularmente evitando los ligandos altamente electronegativos, es crítico para acceder a estados de oxidación más altos como Ru(V).
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