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La transferencia de átomos de oxígeno y la incorporación de agua oxidativa en complejos cuboidales de Mn3MO (n)
Jacob S Kanady1, Jose L Mendoza-Cortes, Emily Y Tsui
1Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, USA.
Journal of the American Chemical Society
|December 18, 2012
Resumen
La reactividad de los modelos de manganeso-calcio cubano en el fotosistema II está controlada por la labilidad del ligando, no solo por el estado de oxidación del manganeso. Este hallazgo arroja luz sobre el complejo mecanismo de evolución del oxígeno.
Área de la Ciencia:
- Química Inorgánica La Química Inorgánica es la química inorgánica.
- La fotoquímica es la fotoquímica.
- La bioquímica es la bioquímica.
Sus antecedentes:
- El complejo de evolución del oxígeno (OEC) en el fotosistema II es crucial para la fotosíntesis, con un grupo de Mn{4) CaO{n}.
- Comprender la reactividad de las fracciones de óxido puente dentro de la OEC es fundamental para dilucidar su función.
- Se sintetizaron como modelos complejos cuboidales Mn{3) MO{n) estructuralmente relevantes (M = Mn, Ca, Sc; n = 3,4).
Objetivo del estudio:
- Investigar las vías mecanicistas de la transferencia de átomos de oxígeno de los complejos Mn(3) MO(n).
- Para explorar el papel de la labilidad del ligando y los estados de oxidación del manganeso en la reactividad OEC.
- Para obtener información sobre los mecanismos propuestos de la OEC que involucran la migración de óxidos.
Principales métodos:
- Síntesis de complejos cuboidales de Mn(3) MO(n).
- Estudios de reactividad utilizando trimetilfosfina (PMe(3)) como aceptor de átomos de oxígeno.
- Cálculos mecánicos cuánticos para investigar las trayectorias de reacción.
- (18) Experimentos de etiquetado con O para rastrear la incorporación de óxidos.
Principales resultados:
- Los modelos de Mn{IV}{3}CaO{4} y Mn{IV}{3}ScO{4} no reaccionaron hacia el PMe{3}.
- A Mn(III) ((2) Mn(IV) ((2) O ((4) cubano reaccionó con PMe ((3) para formar un Mn(III) ((4) O ((3) cubano parcial.
- La mecánica cuántica reveló que la labilidad del ligando (acetato), particularmente con la presencia de Mn (III), facilita la transferencia de átomos de oxígeno.
- Se observó la incorporación de óxido oxidativo en el cubano parcial, con (18) O-etiquetado de apoyo a la migración de óxido.
Conclusiones:
- La transferencia de átomos de oxígeno de las cubanas Mn(3) MO(4) se rige por la labilidad de los ligandos, no solo por el estado de oxidación del manganeso.
- El modelo Mn{IV}{3}CaO{4}, a pesar de su relevancia, no es reactivo, lo que pone de relieve la importancia de las características estructurales específicas.
- Los hallazgos experimentales y computacionales apoyan los mecanismos que involucran la migración de óxidos dentro del grupo OEC.
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