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Un complejo terminal N2 de hierro de alto espín ((I) en un campo débil de ligandos trigonales
Alex McSkimming1, W Hill Harman1
1Department of Chemistry, University of California, Riverside, California 92521, United States.
Journal of the American Chemical Society
|July 3, 2015
Resumen
Los investigadores sintetizaron nuevos complejos de hierro de alto espín que se unen y activan el gas nitrógeno (N2). Este descubrimiento ofrece nuevos conocimientos sobre los mecanismos de fijación de nitrógeno relevantes tanto para la biología como para la industria.
Área de la Ciencia:
- Química bioorgánica Química bioorgánica.
- Química organometálica Química orgánica de los metales.
- Investigación de fijación de nitrógeno Investigación de fijación de nitrógeno
Sus antecedentes:
- El papel crucial del hierro en la fijación biológica e industrial del nitrógeno (fijación de N2) impulsa la investigación de los intermediarios Fe-NxHy.
- Los complejos Fe-(N2) existentes de baja coordinación a menudo usan ligandos donantes, lo que lleva a estados de espín bajos / intermedios o motivos de puente, a diferencia de los ligandos de sulfuro de campo débil del sitio activo de la nitrogenasa.
Objetivo del estudio:
- Para sintetizar y caracterizar nuevos complejos de hierro de alto espín capaces de unirse y activar N2.2.
- Para explorar los complejos Fe-(N2) que imitan el centro Fe de alto espín que se encuentra en el sitio activo de la nitrogenasa.
Principales métodos:
- Síntesis de complejos terminales y puentes Fe-(N2).
- Caracterización utilizando resonancia paramagnética de electrones (EPR) y determinación del momento magnético de la solución.
- Espectroscopia vibratoria (por ejemplo, espectroscopia IR) para evaluar la activación del enlace NN.
- Cálculos de la Teoría Funcional de Densidad (DFT) para aclarar la estructura electrónica.
Principales resultados:
- Se informó de la primera terminal N2 complejo de alta espina (S = 3/2) Fe (I).
- Sintetizó un análogo puente de Fe-(N2)-Fe.
- Estado de alto giro confirmado a través de estudios de EPR y momento magnético.
- Los datos vibratorios indican una activación significativa del enlace NN.
- Los cálculos de DFT muestran deslocalización de espín en el ligando N2 en el adducto terminal.
Conclusiones:
- Con éxito sintetizó y caracterizó complejos Fe (I) -N2 de alto espín sin precedentes.
- Estos complejos representan un avance significativo en el modelado de la química del sitio activo de la nitrogenasa.
- Los hallazgos proporcionan información valiosa sobre la activación del N2 por los centros de hierro de alto espín, relevantes para la catálisis y la química bioinorgánica.
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