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Cambios en la coordinación de los ligandos híbridos de imidazolilfosfina estéricamente exigentes en Pd(0) y Pd(II)

Douglas B Grotjahn¹, Yi Gong, Lev Zakharov

¹Department of Chemistry and Biochemistry, San Diego State University, California 92182-1030, USA. grotjahn@chemistry.sdsu.edu

Journal of the American Chemical Society

|January 13, 2006

Resumen

Los investigadores exploraron nuevos ligandos híbridos para complejos organometálicos de baja coordinación, encontrando que los sustitutos voluminosos de fosfina favorecen la quelación. Este trabajo ofrece información sobre el control de las velocidades de reacción y los productos en la catálisis del paladio a través del diseño del ligando.

Área de la Ciencia:

Química organometálica Química orgánica de los metales.
La catálisis de la catálisis.
Diseño del ligando diseño de ligando.

Sus antecedentes:

Los complejos organometálicos de baja coordinación son cruciales para la catálisis.
Los ligandos híbridos que permiten la hemilabilidad y las interacciones secundarias están ganando atención.
La comprensión de los factores que controlan estas propiedades del ligando es esencial.

Objetivo del estudio:

Para sintetizar e investigar nuevos ligandos de la imidazol-2-ilfosfina.
Para explorar el comportamiento de coordinación de los complejos de paladio resultantes.
Para entender cómo la estructura del ligando influye en la reactividad en la adición oxidativa.

Principales métodos:

Síntesis de tres nuevos ligandos de imidazol-2-ilfosfina con variado volumen estérico.
Formación y caracterización de los complejos L2Pd(0) de dos coordenadas.
Investigación de reacciones de adición oxidativa utilizando difracción de rayos X y espectroscopia de RMN.

Principales resultados:

Los complejos L2Pd(0) sintetizados existen como especies de dos coordenadas y 12 electrones.
Los resultados de las reacciones en adiciones oxidativas son sintonizables por sustituyentes de ligando y sustrato.
Los grupos voluminosos de fosfina (ter-butilo) promueven la quelación eta(2)-P,N, formando complejos monoméricos.
La hemilabilidad se observó en un complejo iónico con intercambio de ligandos dependiente de la temperatura.
El obstáculo estérico alrededor del nitrógeno del imidazol influye en la longitud del enlace Pd-N.

Conclusiones:

El volumen estérico del ligando es un factor clave en el control de la coordinación y la reactividad del complejo de paladio.
Los ligandos de la imidazol-2-ilfosfina ofrecen hemilabilidad sintonizable y capacidades de interacción secundaria.
Este estudio proporciona una base para el diseño de catalizadores organometálicos avanzados.

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