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The Synthesis, Characterization and Reactivity of a Series of Ruthenium N-triphosPh Complexes

The Synthesis, Characterization and Reactivity of a Series of Ruthenium N-triphos^Ph Complexes

Published on: April 10, 2015

Transferencia de protones-electrones concertada en un sistema de terpiridil-benzoato de rutenio con una gran

Virginia W Manner¹, James M Mayer

¹Department of Chemistry, University of Washington, Seattle, Washington 98195-1700, USA.

Journal of the American Chemical Society

|July 3, 2009

Resumen

Los complejos de rutenio con un espaciador de fenilo facilitan las reacciones de transferencia de electrones acoplados a protones (PCET), mostrando una reactividad similar a los análogos no espaciados. Este estudio investiga cómo la distancia de separación impacta la reactividad PCET en complejos de rutenio.

Área de la Ciencia:

Coordinación Química de la Coordinación
La fotoquímica y la fotofísica.
La catálisis es la catálisis.

Sus antecedentes:

La transferencia de electrones acoplados a protones (PCET) es crucial en los sistemas biológicos y la catálisis química.
Comprender la influencia de la estructura molecular, específicamente la distancia entre los sitios aceptores de electrones y protones, es clave para optimizar la reactividad del PCET.
Los complejos de rutenio son ampliamente estudiados por sus propiedades redox y potencial en catálisis.

Objetivo del estudio:

Para investigar el efecto de la separación espacial entre el metal y los sitios de aceptación de protones en la reactividad del PCET.
Para sintetizar y caracterizar nuevos complejos de rutenio con distancias variables entre los centros redox-activos.
Para dilucidar el mecanismo de la PCET en estos sistemas utilizando diferentes donantes de átomos de hidrógeno.

Principales métodos:

Síntesis de complejos de rutenio: Ru (II) (pydic) (tpy-PhCOOH) y sus formas desprotonadas/oxidadas.
Caracterización de los potenciales redox (E1/2) y las propiedades ácido-base (pKa) para determinar el BDFE.
Estudios cinéticos de las reacciones de transferencia de átomos de hidrógeno con TEMPOH y [{t}Bu{2}{OMe}ArOH] utilizando mediciones de velocidad constante y etiquetado isotópico (kH/kD).

Principales resultados:

El complejo sintetizado Ru(III)PhCOO actúa como un fuerte aceptador de átomos de hidrógeno con un BDFE de 87 kcal mol(-1).
A pesar de una separación de 11,2 Å, Ru(III) PhCOO oxida eficientemente el TEMPOH a través de una vía concertada de transferencia de protones-electrones (CPET), con una constante de velocidad de (1.1 ± 0.1) x 10^5 M(-1) s(-1).
La transferencia de hidrógeno de [{t) Bu{2}{OMe}ArOH] a Ru{3}PhCOO fue significativamente más lenta en comparación con un análogo no espaciado, lo que indica un efecto dependiente de la distancia para ciertos donantes.

Conclusiones:

La disposición espacial de los sitios aceptores de electrones y protones influye significativamente en la reactividad del PCET, aunque el CPET todavía puede ocurrir a distancias considerables.
Los complejos de rutenio con ligandos fenil-tpy ofrecen una plataforma sintonizable para el estudio de las relaciones estructura-reactividad en PCET.
Los hallazgos proporcionan información sobre el diseño de catalizadores moleculares eficientes para reacciones redox que involucran transferencia de protones y electrones.

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