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Reducción catalítica de cianuro a amoníaco y metano en un sitio de hierro mononuclear

Christian M Johansen¹, Jonas C Peters¹

¹Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States.

Journal of the American Chemical Society

|February 16, 2024

Resumen

Este estudio detalla un nuevo catalizador de hierro que convierte eficientemente el cianuro en amoníaco y metano. Los hallazgos ofrecen información sobre los mecanismos de las enzimas nitrogenasa y los catalizadores sintéticos para la reducción de nitrógeno y cianuro.

Área de la Ciencia:

Química inorgánica
Catálisis
Química bioorgánica

Sus antecedentes:

Las enzimas nitrogenasas son cruciales para convertir el nitrógeno atmosférico en amoníaco.
El cianuro (CN-) es un análogo isoelectrónico del N2, por lo que es un sustrato útil para el estudio de mecanismos catalíticos similares a la nitrogenasa.
Se están desarrollando catalizadores de hierro sintéticos para imitar y comprender la actividad de la nitrogenasa.

Objetivo del estudio:

Investigar la reducción catalítica del cianuro (CN-) a amoníaco (NH3) y metano (CH4) utilizando un catalizador de hierro sintético.
Comparar los mecanismos de reacción de la reducción de CN con los de la reducción de N2 por catalizadores de hierro relacionados.
Para aclarar los intermediarios involucrados en el ciclo catalítico de la reducción de CN.

Principales métodos:

Síntesis y caracterización de un complejo de cianuro de hierro ligado a la tris ((phosphine) silyl ((P3Si) Fe ((CN)).
Reducción electrocatalítica de CN- en presencia de un exceso de ácido y un reductor ((C6H6) 2Cr).
Estudios mecanicistas, incluida la identificación intermedia y el análisis computacional.

Principales resultados:

El catalizador (P3Si) Fe ((CN) demostró una alta selectividad para la reducción de CN a NH3 y CH4, con números de rotación de hasta 73.
Se identificaron productos intermedios clave como los isocyanuros de hierro y las aminocarbinas terminales de hierro.
Se encontró que un intermediario de carbeno de Fischer propuesto era crucial para la distribución del producto observado, diferenciándolo de las vías de reducción de N2.

Conclusiones:

El catalizador de hierro desarrollado reduce efectivamente el cianuro, proporcionando un sistema modelo para estudiar la reactividad similar a la nitrogenasa.
La comprensión del mecanismo de reducción de la CN, en particular el papel del intermediario del carbeno de Fischer, ofrece comparaciones valiosas con las vías de reducción del N2.
Esta investigación contribuye al diseño de catalizadores sintéticos avanzados para la fijación del nitrógeno y las transformaciones químicas relacionadas.

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