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Actividad de hidrogenación catalítica y determinación de la estructura electrónica de los complejos alquilo e hidruro
Renyuan Pony Yu1, Jonathan M Darmon, Carsten Milsmann
1Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States.
Journal of the American Chemical Society
|August 24, 2013
Resumen
Un nuevo complejo metilo de cobalto, ((iPr) CNC) CoCH3, cataliza eficientemente la hidrogenación de alquenos difíciles. Este estudio revela la complejidad
Área de la Ciencia:
- Química organometálica Química orgánica de los metales.
- La catálisis de la catálisis.
- Síntesis orgánica La síntesis orgánica.
Sus antecedentes:
- Los complejos de cobalto se exploran cada vez más como alternativas a los catalizadores de metales preciosos.
- La hidrogenación de alquenos estéricamente impedidos y no activados sigue siendo un desafío significativo en la síntesis orgánica.
Objetivo del estudio:
- Para evaluar la actividad catalítica de un complejo metilo de cobalto de piridina bis ((arylimidazol-2-ilideno), ((iPr) CNC) CoCH3, para la hidrogenación de alquenos.
- Investigar la reactividad y las propiedades electrónicas de las especies reducidas de cobalto derivadas de este complejo.
Principales métodos:
- Experimentos de hidrogenación catalítica utilizando varios alquenos bajo condiciones suaves (22 °C, 4 atm H2).
- Preparación y caracterización de los intermediarios de hidruro de cobalto.
- Estudios espectroscópicos (por ejemplo, EPR) y computacionales (por ejemplo, cálculos de densidad de espín) para sondear el carácter radical.
Principales resultados:
- ((iPr)CNC) CoCH3 demostró una alta actividad como un precatalizador para la hidrogenación de alquenos estéricamente impedidos.
- Se observó la formación de un complejo de hidruro de cobalto, ((iPr) CNC) CoH.
- Evidencia de la actividad redox del ligando de piridina bis ((arylimidazol-2-ilideno), que forma radicales centrados en la piridina en la química reducida del cobalto.
Conclusiones:
- El complejo de cobalto evaluado es un precatalizador altamente activo para la hidrogenación de alquenos.
- El ligando de piridina bis ((arylimidazol-2-ylideno) es redox-activo, participando en las vías radicales.
- Esto sugiere potencial para el desarrollo de otros ligandos de pinza basados en piridina redox-activa para la catálisis.
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