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Espectroscopia de RMN de estado sólido (63) Cu y (65) Cu de complejos inorgánicos y organometálicos de cobre (I)
Joel A Tang1, Bobby D Ellis, Timothy H Warren
1Department of Chemistry and Biochemistry, University of Windsor, Windsor, Ontario, Canada N9B 3P4.
Journal of the American Chemical Society
|October 11, 2007
Resumen
La resonancia magnética nuclear (RMN) de cobre-63/65 en estado sólido revela cómo los gradientes de campo eléctrico influyen en los complejos de cobre. Este estudio caracteriza las constantes de acoplamiento cuádrupolar y las anisotropías de blindaje químico en diversos entornos de coordinación.
Área de la Ciencia:
- Química inorgánica y organometálica en estado sólido.
- Espectroscopía de Resonancia Magnética Nuclear (RMN) Espectroscopía de Resonancia Magnética Nuclear (RMN) Espectroscopía de Resonancia Magnética Nuclear (RMN) Espectroscopía de Resonancia Magnética Nuclear (RMN) Espectroscopía de Resonancia Magnética Nuclear (RMN) Espectroscopía de Resonancia Magnética Nuclear (RMN) Espectroscopía de Resonancia Magnética Nuclear (RMN) Espectroscopía de Resonancia Magnética Nuclear (RMN) Espectroscopía de Resonancia Magnética Nuclear (RMN).
- Química cuántica y modelado computacional.
Sus antecedentes:
- Los complejos de cobre exhiben diversas geometrías de coordinación.
- Los gradientes de campo eléctrico (EFG) tienen un impacto significativo en los espectros de RMN de los núcleos cuadrupolares.
- Comprender la relación entre la estructura molecular y los parámetros de RMN es crucial.
Objetivo del estudio:
- Para investigar la RMN de estado sólido 63Cu y 65Cu en varios entornos de coordinación de cobre.
- Para correlacionar las variaciones estructurales y la simetría con los tensores de gradiente de campo eléctrico (EFG).
- Para determinar las constantes de acoplamiento cuadrupolar (CQ) y las anisotropías de blindaje químico (CSA) para sitios asimétricos de cobre.
Principales métodos:
- Experimentos de RMN de estado sólido de 63Cu y 65Cu utilizando secuencias de pulso de eco de Hahn y QCPMG.
- Adquisición escalonada de frecuencia para patrones de polvo de alta señal a ruido.
- 31P Girado de ángulo mágico de polarización cruzada (CP/MAS) RMN para pares de giros Cu-P.
- Cristalografía de rayos X y cálculos teóricos (Hartree-Fock, DFT).
Principales resultados:
- Los valores de CQ observados oscilan entre 22,0 y 71,0 MHz para los sitios asimétricos de Cu.
- Spectra mostró amplios patrones de transición central (760 kHz a 6.7 MHz) debido a las grandes interacciones cuádrupolares.
- Se detectaron CSA significativos (1000 a 1500 ppm) en algunos complejos.
- Los datos de RMN, combinados con la cristalografía y la teoría, permitieron la determinación de las orientaciones del tensor EFG y el signo CQ.
Conclusiones:
- La RMN en estado sólido es efectiva para caracterizar diversos entornos de coordinación de cobre.
- Los parámetros tensores de interacción de RMN están directamente relacionados con la estructura molecular y la simetría.
- El estudio proporciona información sobre la estructura electrónica de los complejos de cobre (I) a través de un análisis detallado de RMN.
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