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2,3,5,6-Tetrafluorofenilnitren-4-yl: caracterización espectroscópica de resonancia paramagnética de electrones de un
Wolfram Sander1, Dirk Grote, Simone Kossmann
1Lehrstuhl für Organische Chemie II, Ruhr-Universität Bochum, D-44780 Bochum, Germany. wolfram.sander@rub.de
Journal of the American Chemical Society
|March 11, 2008
Resumen
Se logró la síntesis de un nuevo tetrafluorofenilnitren-4-il trirrádico. La resonancia paramagnética de electrones y la espectroscopia infrarroja confirmaron su robusto cuarteto de estado fundamental, caracterizado como un sigma, sigma, pi-trirradical único.
Área de la Ciencia:
- Química orgánica es la química orgánica.
- La espectroscopia es una técnica de espectroscopia.
- Química cuántica es la química cuántica.
Sus antecedentes:
- La química del nitreno y las especies radicales son cruciales en las transformaciones sintéticas.
- Comprender la estructura electrónica y los estados de espín de los intermediarios reactivos es fundamental.
- Estudios anteriores indicaron el potencial de estados de alto espín en moléculas relacionadas.
Objetivo del estudio:
- Para sintetizar y caracterizar el 2,3,5,6-tetrafluorofenilnitreno-4-il trirrádico.
- Para determinar el estado electrónico de base (estado de espín) del trirrádico sintetizado.
- Para investigar los parámetros de división de campo cero (ZFS) y la estructura electrónica utilizando métodos computacionales.
Principales métodos:
- Fotólisis de 2,3,5,6-tetrafluoro-4-iodo-fenil azido en el argón a 4 K. Fotólisis de 2,3,5,6-tetrafluoro-4-iodo-fenil azido en el argón a 4 K. Fotólisis de 2,3,5,6-tetrafluoro-4-iodo-fenil azido en el argón a 4 K. Fotólisis de 2,3,5,6-tetrafluoro-4-iodo-fenil azido en el argón a 4 K. Fotólisis de 2,3,5,6-tetrafluoro-4-iodo-fenil azido en el argón
- Espectroscopia de resonancia paramagnética de electrones (EPR) para observar el trirrádico.
- Espectroscopia infrarroja (IR) para el análisis de vibraciones y la confirmación del estado de giro.
- Ab initio y cálculos de la Teoría Funcional de Densidad (DFT) para la estructura electrónica y el análisis ZFS.
Principales resultados:
- Síntesis y aislamiento exitosos de 2,3,5,6-tetrafluorofenilnitren-4-il (5) en su estado cuarteto.
- Observación de los parámetros significativos de división de campo cero (ZFS) D/hcd = 0.285 cm-1 y E/hcd = 0.043 cm-1.
- Confirmación de un estado básico de cuarteto robusto, consistente con la espectroscopia IR y los cálculos de DFT, descrito como un sigma, sigma, pi-trirradical.
Conclusiones:
- El trirrádico 2,3,5,6-tetrafluorofenilnitren-4-il exhibe una estructura electrónica sin precedentes de sigma, sigma, pi-trirrádico.
- El estado fundamental del cuarteto es estable y está bien caracterizado por la espectroscopia EPR e IR.
- Los cálculos de DFT reproducen con precisión el ZFS observado y proporcionan información sobre las propiedades electrónicas de esta especie radical única.
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