Video Experimental Relacionado

Updated: Aug 20, 2026

Accessing Valuable Ligand Supports for Transition Metals: A Modified, Intermediate Scale Preparation of 1,2,3,4,5-Pentamethylcyclopentadiene

Accessing Valuable Ligand Supports for Transition Metals: A Modified, Intermediate Scale Preparation of 1,2,3,4,5-Pentamethylcyclopentadiene

Published on: March 20, 2017

Complejos sándwich de zirconio con ligandos indenilo eta(9): precursores bien definidos para las reacciones de

Christopher A Bradley¹, Ivan Keresztes, Emil Lobkovsky

¹Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, NY 14853, USA.

Journal of the American Chemical Society

|December 23, 2004

Resumen

Los investigadores sintetizaron nuevos complejos sándwich de bis-indenilo-zirconio. Estos complejos exhiben una coordinación y reactividad única con las olefinas y las alquinas, formando compuestos de hidruro de alilo y zirconaciclopentanos.

Área de la Ciencia:

Química organometálica Química orgánica de los metales.
Coordinación Química de la Coordinación
Complejos de zirconio Complejos de zirconio

Sus antecedentes:

Los complejos de bis-ciclopentadienil zirconio son catalizadores bien establecidos.
La exploración de nuevos marcos de ligandos es crucial para descubrir nuevas reactividades.

Objetivo del estudio:

Para sintetizar y caracterizar nuevos complejos sándwich de bis-indenilo-zirconio.
Para investigar los modos de coordinación y el comportamiento de solución de estos complejos.
Para explorar su reactividad con sustratos insaturados como olefinas y alquinas.

Principales métodos:

Síntesis a través de eliminación reductora de alcano o reducción de metales alcalinos.
Cristalografía de rayos X para la determinación estructural.
Espectroscopia de RMN EXSY y de temperatura variable para estudios dinámicos.

Principales resultados:

Se prepararon complejos aislables de bis-indenilo-zirconio con sustituyentes sililo o alquilo.
Se observó una coordinación inédita de un ligando indenilo y se confirmó cristalográficamente.
Se demostró una rápida interconversión entre los modos de coordinación eta ((5) y eta ((9) en solución.
Los complejos reaccionan fácilmente con olefinas y alquinas a temperatura ambiente.
Se observó una activación preferente de C-H de los aductos de olefinas para formar hidruros de alilo, en contraste con los sistemas de bis-ciclopentadienilo.

Conclusiones:

Los nuevos complejos de bis-indenilo-zirconio ofrecen propiedades estructurales y electrónicas únicas.
La coordinación eta(9) observada y el comportamiento dinámico amplían la comprensión de la coordinación del ligando indenilo.
Estos complejos representan precursores efectivos para la química del zirconio de baja valencia.
Su distinta reactividad, incluida la activación preferencial de C-H, destaca su potencial en la catálisis y la síntesis orgánica.

Más Videos Relacionados

Synthesis of Nine-atom Deltahedral Zintl Ions of Germanium and their Functionalization with Organic Groups

Synthesis of Nine-atom Deltahedral Zintl Ions of Germanium and their Functionalization with Organic Groups

Published on: February 11, 2012

Amide Coupling Reaction for the Synthesis of Bispyridine-based Ligands and Their Complexation to Platinum as Dinuclear Anticancer Agents

Amide Coupling Reaction for the Synthesis of Bispyridine-based Ligands and Their Complexation to Platinum as Dinuclear Anticancer Agents

Published on: May 28, 2014

Videos de Conceptos Relacionados

Alkenes via Reductive Coupling of Aldehydes or Ketones: McMurry Reaction

Alkenes via Reductive Coupling of Aldehydes or Ketones: McMurry Reaction

The radical dimerization of ketones or aldehydes gives vicinal diols through a pinacol coupling reaction. However, the behavior of titanium metals used for the reaction as a source of electrons is unusual. When the reaction is carried out in the presence of titanium, diols can be isolated at low temperatures. Else titanium further reacts with diols, forming alkenes through the McMurry reaction.

Diazonium Group Substitution with Halogens and Cyanide: Sandmeyer and Schiemann Reactions

Diazonium Group Substitution with Halogens and Cyanide: Sandmeyer and Schiemann Reactions

Arenediazonium substitution reactions occur when the diazonium group is substituted by various functional groups such as halides, hydroxyl, nitrile, etc. For instance, arenediazonium salts react with copper(I) salts of chloride, bromide, or cyanide to form corresponding aryl chlorides, bromides, and nitriles. These reactions are named Sandmeyer reactions. Although the mechanism of this reaction is complicated, as illustrated in Figure 1, they are believed to progress via an aryl copper...

Ziegler–Natta Chain-Growth Polymerization: Overview

Ziegler–Natta Chain-Growth Polymerization: Overview

Ziegler–Natta polymerization is another form of addition or chain‐growth polymerization used for synthesizing linear polymers over branched polymers. The catalyst used for polymerization is the Ziegler–Natta catalyst, named after Karl Ziegler and Giulio Natta, who developed it in 1953. This catalyst is an organometallic complex of titanium tetrachloride and triethyl aluminum, with the active form of the catalyst being an alkyl titanium compound. Using the Ziegler–Natta catalyst, high molecular...

Aryldiazonium Salts to Azo Dyes: Diazo Coupling

Aryldiazonium Salts to Azo Dyes: Diazo Coupling

The reaction of weakly electrophilic aryldiazonium (also called arenediazonium) salts with highly activated aromatic compounds leads to the formation of products with an —N=N— link, called an azo linkage. This reaction, presented in Figure 1, is known as diazo coupling and occurs without the loss of the nitrogen atoms of the aryldiazonium salt. Highly activated aromatic compounds such as phenols or arylamines favor the diazo coupling reaction. The coupling generally occurs at the para position.

[4+2] Cycloaddition of Conjugated Dienes: Diels–Alder Reaction

[4+2] Cycloaddition of Conjugated Dienes: Diels–Alder Reaction

The Diels–Alder reaction is an example of a thermal pericyclic reaction between a conjugated diene and an alkene or alkyne, commonly referred to as a dienophile. The reaction involves a concerted movement of six π electrons, four from the diene and two from the dienophile, forming an unsaturated six-membered ring. As a result, these reactions are classified as [4+2] cycloadditions.

Complexation Equilibria: The Chelate Effect

Complexation Equilibria: The Chelate Effect

In complexation reactions, metal atoms or cations interact with ligands to form donor-acceptor adducts called metal complexes. Ligands that bind through one donor site are monodentate, ligands with two donor sites are bidentate, and those with more than two donor sites are polydentate ligands. For example, ethylene diamine is a bidentate ligand that binds through two nitrogen donor atoms, forming a five-membered ring. EDTA is a polydentate ligand that binds through four oxygen and two nitrogen...