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Cobre de tres coordenadas ((I) complejos de radicales amido y aminilo
Neal P Mankad1, William E Antholine, Robert K Szilagyi
1Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
Journal of the American Chemical Society
|March 4, 2009
Resumen
Un nuevo complejo de cobre imita las proteínas de cobre azul con una rápida transferencia de electrones. La forma oxidada es un radical cobre-aminilo, no cobre-amido, que muestra una reactividad única.
Área de la Ciencia:
- La química de la coordinación es química de la coordinación.
- Química bioorgánica y bioorgánica.
- Química organometálica de las sustancias orgánicas.
Sus antecedentes:
- Las proteínas de cobre azul son metalloenzimas vitales con sitios activos únicos de tipo 1.
- Comprender su estructura electrónica es clave para imitar su función.
- Los complejos de cobre con ligandos específicos pueden modelar estos sitios activos.
Objetivo del estudio:
- Para sintetizar y caracterizar un complejo de cobre de tres coordenadas como un modelo funcional para las proteínas de cobre azul tipo 1.
- Para investigar la estructura electrónica del complejo de cobre oxidado.
- Para explorar la reactividad que surge de su configuración electrónica única.
Principales métodos:
- Aislamiento y caracterización estructural de complejos de cobre en los estados de oxidación Cu (I) y Cu (II).
- Medición de las velocidades de reacción de transferencia de electrones de autointercambio.
- Espectroscopia de absorción de rayos X de múltiples bordes (XAS) y resonancia paramagnética de electrones de múltiples frecuencias (EPR).
- Cálculos de la teoría funcional de la densidad (DFT).
Principales resultados:
- Se sintetizó y caracterizó con éxito un sistema Cu-NR(2) de tres coordenadas.
- El sistema exhibe una alta constante de la velocidad de transferencia de electrones de auto-intercambio (kS) >= 10 7 M-1 s-1).
- Los análisis espectroscópicos y computacionales revelan que la forma oxidada es un radical Cu(I) -aminyl, con ~70% de electrones no apareados en la unidad NR(2), en lugar de una especie Cu(II) -amido.
Conclusiones:
- El complejo de cobre sintetizado sirve como un modelo funcional para los sitios activos de la proteína de cobre azul tipo 1.
- La especie oxidada posee una estructura electrónica inusual, mejor descrita como un radical Cu(I) -aminyl.
- Esta configuración electrónica única permite una nueva reactividad, incluida la transferencia de átomos de hidrógeno y las reacciones de acoplamiento C-C.
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