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(Butadieno) metaloceno/B ((C6F5) 3 vía a los sistemas catalizadores para la polimerización estereoselectiva del

Joachim W Strauch¹, Jean-Luc Fauré, Stéphane Bredeau

¹Organisch-Chemisches Institut der Universität Münster, Corrensstrasse 40, D-48149 Muenster, Germany.

Journal of the American Chemical Society

|February 20, 2004

Resumen

Los nuevos catalizadores de ansa-zirconoceno permiten la polimerización estereospecífica del metacrilato de metilo. El bulto estérico influye en la táctica del polímero, y los contraaniones afectan la estereoselectividad en este sistema de metalloceno de un solo componente.

Área de la Ciencia:

Química organometálica Química orgánica de los metales.
La ciencia de los polímeros es la ciencia de los polímeros.
La catálisis de la catálisis.

Sus antecedentes:

Los dicloruros de ansa-zirconoceno son precursores de los catalizadores del metalloceno.
El butadieno-magnesio se utiliza para sintetizar (eta(4) -butadieno) metalocenos.
Los ácidos de Lewis basados en boro activan los metallocenos para la polimerización.

Objetivo del estudio:

Para sintetizar y caracterizar los nuevos complejos (butadieno) metaloceno/borato de betaína.
Investigar su actividad como catalizadores de un solo componente para la polimerización del metacrilato de metilo.
Explorar la influencia del bulto estérico y las contraaniones en la táctica y la estereoselectividad del polímero.

Principales métodos:

Síntesis de dicloruros de ansa-zirconoceno y su reacción con butadieno-magnesio.
Activación con tris ((pentafluorofenil) boro para formar complejos de betaína.
La polimerización del metacrilato de metilo y la caracterización del poli (metacrilato de metilo resultante) utilizando RMN y espectrometría de masas.

Principales resultados:

Formación de complejos de (butadieno) metaloceno/borato betaína (18a-e) con formación preferente de isómero Z y posterior reordenamiento a isómeros E.
Estos sistemas dipolares funcionan como catalizadores activos de un solo componente para la polimerización estereospecífica del metacrilato de metilo.
El aumento de la masa estérica del ligando ansa-zirconoceno conduce a una mayor isotacticidad en el poli (methacrilato de metilo); las contraaniones impactan significativamente la estereoselectividad.

Conclusiones:

Los nuevos complejos dipolares de betaína derivados de ansa-zirconocenos son catalizadores efectivos de un solo componente para la polimerización estereospecífica.
El volumen estérico del ligando y la identidad del contraanión son factores críticos que controlan la táctica y la estereoselectividad del polímero.
Se observaron y caracterizaron con éxito los intermedios de reacción y las especies oligoméricas, proporcionando conocimientos mecánicos.

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