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Reducción catalítica a sililaminas y termodinámica de la unión de N2 en el plano cuadrado Fe

Demyan E Prokopchuk¹, Eric S Wiedner¹, Eric D Walter²

¹Center for Molecular Electrocatalysis, Pacific Northwest National Laboratory , P.O. Box 999, Richland, Washington 99352, United States.

Journal of the American Chemical Society

|June 15, 2017

Resumen

Este estudio introduce un nuevo complejo de hierro estabilizado por un ligando P4N2 que cataliza la silición del nitrógeno (N2) a temperatura ambiente. Este catalizador alcanza altos números de rotación y demuestra una afinidad de unión de N2 significativa a través de múltiples estados de oxidación.

Área de la Ciencia:

Química inorgánica
Química organometálica
Catálisis

Sus antecedentes:

Los ligandos tetradentados P4N2 son cruciales para estabilizar los complejos de hierro en diferentes estados de oxidación.
Los complejos de hierro se investigan cada vez más como catalizadores sostenibles para la fijación de nitrógeno.

Objetivo del estudio:

Para sintetizar y caracterizar un nuevo complejo de hierro piramidal cuadrado con un ligando P4N2.
Evaluar la actividad catalítica del complejo de hierro en la silición del nitrógeno (N2).
Para investigar la termodinámica de la unión del N2 al centro del hierro.

Principales métodos:

Síntesis del complejo piramidal cuadrado Fe0(N2)(P4N2).
Ensayos catalíticos para la conversión de N2 en N (SiR3) 3.
La electroquímica de alta presión y la espectroscopia UV-vis de temperatura variable para mediciones termodinámicas.
Cristalografía de rayos X, 57Fe Mössbauer y espectroscopia EPR para la caracterización estructural y electrónica.

Principales resultados:

El complejo Fe0 ((N2) ((P4N2) cataliza la silición del N2 a temperatura ambiente con un número de rotación elevado (hasta 65 equivalentes de N ((SiMe3) 3 por Fe).
Las presiones elevadas de N2 mejoran significativamente la solubilidad de N2 y la afinidad termodinámica de unión.
La energía libre de la unión de N2 a través de los estados de oxidación Fe0, FeI y FeII abarca más de 37 kcal mol-1.

Conclusiones:

El ligando P4N2 estabiliza eficazmente los complejos de hierro, lo que permite una catálisis de silición de N2 eficiente.
Las altas presiones de N2 son beneficiosas para el proceso catalítico al mejorar la unión de N2.
Los análisis espectroscópicos y cristalográficos detallados proporcionan una comprensión completa de los estados redox del hierro y la energía de unión del N2.

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