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Un complejo dihidrógeno alargado de iridio
Vincent Pons1, D Michael Heinekey
1Department of Chemistry, Box 351700, University of Washington, Seattle, Washington 98195-1700, USA.
Journal of the American Chemical Society
|July 10, 2003
Resumen
Este estudio revela un complejo de iridio dicationic, [Cp*Ir(dmpm) H2]2+, que existe como una mezcla de isómeros cis y trans. Se propone un equilibrio dinámico entre las formas cis-dihidruro y dihidrógeno para el isómero predominante.
Área de la Ciencia:
- Química organometálica Química orgánica de los metales.
- Coordinación Química de la Coordinación
- Química Inorgánica La Química Inorgánica es la química inorgánica.
Sus antecedentes:
- Los complejos de iridio son catalizadores vitales en varias transformaciones químicas.
- Comprender la estructura y la dinámica de los ligandos hidruro es crucial para el esclarecimiento del mecanismo de reacción.
Objetivo del estudio:
- Para sintetizar y caracterizar un nuevo complejo de iridio dicationic nuevo, [Cp*Ir(dmpm) H2]2+.
- Para investigar los isómeros estructurales y el comportamiento dinámico del complejo sintetizado.
Principales métodos:
- Síntesis del complejo dicationic usando [Cp*Ir(dmpm) Cl]Cl y [Et3Si]B(ArF) 4 bajo el gas de hidrógeno.
- Caracterización mediante espectroscopia de Resonancia Magnética Nuclear (RMN) (1H, 13C, 31P) y mediciones del tiempo de relajación (T1).
- Etiquetado isotópico con deuterio (gas HD) para estudiar la dinámica de los ligandos.
Principales resultados:
- Formación del complejo dicationico [Cp*Ir(dmpm) H2]2+ (1) en dos formas isoméricas (proporción 97:3).
- Asignación de una estructura cis-dihidruro o dihidrógeno al isómero mayor (1-cis) y una estructura transoide al isómero menor (1-trans) basada en acoplamientos 2JH-P y mediciones de T1.
- Observación de las constantes de acoplamiento 1JH-D dependientes de la temperatura y los desplazamientos químicos para el isómero cis deuterado (1-cis-d1), lo que indica un comportamiento dinámico.
Conclusiones:
- El isómero 1-cis predominante existe en un equilibrio dinámico entre un cis-dihidruro y un complejo de dihidrógeno.
- La temperatura influye significativamente en el equilibrio, afectando los parámetros espectroscópicos observados.
- Este estudio proporciona información sobre la naturaleza fluxional de los ligandos hidruro en complejos organometálicos.
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