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Se evita la hipervalencia: moléculas simples de BrF3 y BrF5 sustituidas. Estructuras, termoquímica y afinidades
Qianshu Li1, Liangfa Gong, Yaoming Xie
1Department of Chemistry, School of Science, Beijing Institute of Technology, Beijing 100081, People's Republic of China.
Journal of the American Chemical Society
|November 13, 2004
Resumen
Este estudio revela que los complejos de fluoruro de hidrógeno de bromo, no las estructuras hipervalentes, son las formas más estables de HBrF ((n) (n=2, 4). Estos complejos presentan enlaces de hidrógeno y tienen afinidades electrónicas significativas, comparables a los sistemas halógenos relacionados.
Área de la Ciencia:
- Química computacional es la química computacional.
- Química cuántica es la química cuántica.
- Química Inorgánica La Química Inorgánica es la química inorgánica.
Sus antecedentes:
- La Teoría Funcional de Densidad (DFT) y los métodos híbridos Hartree-Fock/DFT son cruciales para predecir las propiedades moleculares.
- Comprender la estabilidad y la reactividad de los compuestos halogenados es importante en química.
Objetivo del estudio:
- Para investigar las estructuras moleculares, la termoquímica y las afinidades electrónicas de los fluoruros de hidrógeno de bromo HBrF ((n) y sus aniones (n = 2, 4).
- Para determinar las configuraciones más estables, identificando si prevalecen las estructuras hipervalentes o complejas.
Principales métodos:
- Empleó cinco métodos DFT y Hartree-Fock/DFT híbridos.
- Se utilizan conjuntos de bases de doble zeta más polarización (DZP++) con funciones difusas.
- Estructuras moleculares calculadas, termoquímica y afinidades de electrones.
Principales resultados:
- Se predice que los mínimos globales para HBrF (n) /HBrF (n) (n = 2, 4) serán complejos enlazados por hidrógeno, no estructuras hipervalentes.
- La disociación favorable en HF, una molécula con alta energía de disociación, impulsa la formación de estos complejos.
- Afinidades calculadas de electrones adiabáticos (EA) de 3.69 eV para HBrF2 y 4.38 eV para HBrF4 utilizando BHLYP.
Conclusiones:
- Las estructuras hipervalentes de HBrF ((n) son energéticamente desfavorables en comparación con los complejos enlazados por hidrógeno.
- La estabilidad de estos complejos está influenciada por la fuerte energía de disociación de HF.
- Las afinidades electrónicas calculadas son comparables a las de los sistemas relacionados que contienen Br, Cl y F.
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