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Estructura molecular del protón solvatado en sales aisladas. Bonos H cortos, fuertes y de baja barrera (SSLB, por sus
Daniel Stasko1, Stephan P Hoffmann, Kee-Chan Kim
1Department of Chemistry, University of California, Riverside, California 92521-0403, USA.
Journal of the American Chemical Society
|November 15, 2002
Resumen
Los nuevos aniones de carborano permiten que las sales de protones solvados estables y caracterizadas. Estos ácidos de Brønsted ofrecen una entrega de protones ajustable y una mayor estabilidad térmica para aplicaciones de química orgánica.
Área de la Ciencia:
- Química Inorgánica La Química Inorgánica es la química inorgánica.
- Química supramolecular de las moléculas.
- Química Física es la química física.
Sus antecedentes:
- Los aniones de carborano icosaédricos son grandes, inertes y débilmente básicos.
- Las sales de protones solvados son cruciales en la síntesis orgánica y la catálisis.
- Las fuentes de protones existentes como [H(OEt(2))(2)][BAr(F) ] tienen limitaciones en la estabilidad térmica.
Objetivo del estudio:
- Para sintetizar y caracterizar nuevas sales de protones solvatados utilizando aniones de carborano.
- Para investigar la estructura y las propiedades de estos ácidos de Brønsted.
- Para comparar su estabilidad y acidez con los agentes protonantes existentes.
Principales métodos:
- Síntesis de los aniones de carborano: CHB(11)R(5)X(6)(-) (R = H, Me; X = Cl, Br).
- Aislamiento y caracterización estructural de sales de protones solvados discretos [H, solvente, x, CHB, R, 5X, 6] utilizando disolventes donantes de átomos O.
- Análisis espectroscópico (IR) y cálculos de la Teoría Funcional de Densidad (DFT).
Principales resultados:
- Con éxito aislado y caracterizado sales de protones solvados con carborano contraiones.
- Acidez sintonizable demostrada y mayor estabilidad térmica en comparación con los ácidos a base de tetrafenilborato.
- Se identificaron enlaces de hidrógeno cortos, fuertes y de baja barrera (SSLB) en los cationes [H(solvente) ((2))) ((+)).
- Se observaron bandas IR ampliadas características indicativas de enlaces de hidrógeno SSLB.
Conclusiones:
- Los aniones de carborano proporcionan contrarios robustos para los ácidos Brønsted de protones solvados estables.
- Estos nuevos ácidos ofrecen ventajas en la entrega de protones y la estabilidad térmica para los disolventes orgánicos.
- Los datos estructurales y computacionales aclaran la naturaleza del enlace de hidrógeno SSLB en disolventes protonados.
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