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Evaluación cuantitativa de las interacciones Se...F débiles y sin enlaces y su notable naturaleza como interacciones
Michio Iwaoka1, Hiroto Komatsu, Takayuki Katsuda
1Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Komaba, Meguro-ku, Tokyo 153-8902, Japan.
Journal of the American Chemical Society
|February 28, 2002
Resumen
La investigación de las interacciones selenio-fluorino en compuestos de organoselenio reveló que las temperaturas más bajas fortalecen estos enlaces. Los cálculos químicos cuánticos confirmaron las interacciones orbitales que impulsan este fenómeno.
Área de la Ciencia:
- Química orgánica es la química orgánica.
- Química Física es la química física.
- Química computacional es la química computacional.
Sus antecedentes:
- Interacciones de Se...F intramoleculares no unidas débiles fueron previamente identificadas en derivados del fluoruro de o-selenobenzil.
- Comprender la naturaleza y la fuerza de estas interacciones es crucial para predecir el comportamiento molecular.
Objetivo del estudio:
- Para evaluar la dependencia de la temperatura del acoplamiento de espín nuclear (J(Se...F)) en el cianato de 2-(fluorometil) fenilseleninilo (1a) y el diselenido de bis[2-(fluorometil) fenil] (1e).
- Para determinar la estabilidad energética de los conformadores con y sin interacciones Se...F.
- Para dilucidar los factores electrónicos que rigen las interacciones Se...F.
Principales métodos:
- Espectroscopia de resonancia magnética nuclear (RMN) dependiente de la temperatura para medir el acoplamiento J...F.
- Análisis rápido del modelo de equilibrio para evaluar la estabilidad conformacional.
- Cálculos químicos cuánticos (QC) y análisis de la órbita de enlace natural (NBO).
Principales resultados:
- J(Se...F) aumentó significativamente con la disminución de la temperatura tanto para 1a como para 1e, lo que indica un fortalecimiento de las interacciones Se...F.
- Se encontró que el conformador A, que presenta una interacción Se...F intramolecular, es más estable en entalpía que el conformador B.
- Los efectos del disolvente fueron mínimos, lo que sugiere una naturaleza no electrostática para las interacciones Se...F, con n(F) -->sigma*(Se-X) superposición orbital siendo un factor clave.
Conclusiones:
- Las interacciones Se...F intramoleculares se fortalecen a temperaturas más bajas.
- Estas interacciones son impulsadas principalmente por la superposición orbital (n(F) -->sigma*(Se-X)) en lugar de las fuerzas electrostáticas.
- Los hallazgos proporcionan información sobre el enlace no covalente en los compuestos de organoselenio.
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