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TpPtMe (((H) ((2)): ¿por qué hay una mezcla H/D del grupo metilo pero no hay pérdida de metano?
Mark A Iron1, H Christine Lo, Jan M L Martin
1Department of Organic Chemistry, Weizmann Institute of Science, 76100 Rehovot, Israel.
Journal of the American Chemical Society
|June 13, 2002
Resumen
El complejo de hidrido-tris (pyrazolyl) borato de platino TpPtMe (H) resiste la pérdida de metano debido a su rígida estructura de ligando. Sin embargo, se somete fácilmente a una mezcla H/D reversible con metanol desterrado.
Área de la Ciencia:
- Química organometálica Química orgánica de los metales.
- Química computacional es la química computacional.
- Mecanismo de reacción Elucidación.
Sus antecedentes:
- La reactividad de los complejos de platino con los ligandos hidrido y metilo es crucial para la catálisis.
- Comprender los efectos de los ligandos en la estabilidad compleja y las vías de reacción es clave.
- TpPtMe (((H) ((2) presenta un caso único de estabilidad contra la pérdida de metano.
Objetivo del estudio:
- Para investigar la reactividad de TpPtMe (((H) ((2), específicamente su resistencia a la pérdida de metano.
- Para dilucidar el mecanismo de la mezcla H/D observado con disolventes deuterados.
- Determinar el papel del ligando Tp rígido en la reactividad observada.
Principales métodos:
- Se emplearon cálculos de la Teoría Funcional de Densidad (DFT) para estudiar la reacción.
- Los cálculos se realizaron en el nivel de teoría mPW1k/LANL2DZ+P//mPW1k/LANL2DZ.
- Para el análisis comparativo se utilizó un sistema modelo, [{NH}}}3)) }3) PtMe{H}{2) ]{+).
Principales resultados:
- La rigidez del ligando Tp impide la geometría trans necesaria para la eliminación del metano, por lo que es energéticamente desfavorable.
- La mezcla H/D reversible de los ligandos metilo e hidruro ocurre fácilmente a través de un intermediario eta{2-CH) -CH{4).
- No se observó pérdida de metano, lo que confirma el efecto estabilizador del ligando Tp.
Conclusiones:
- La rigidez del ligando de Tp es el factor principal que inhibe la pérdida de metano en TpPtMe ((H) ((2).
- La codificación H / D es un proceso fácil, que se produce a través de una ruta intermedia distinta.
- Los cálculos energéticos precisos para sistemas similares requieren niveles específicos de DFT, como mPW1k/SDB-cc-pVDZ.
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