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The Organometallic HyperTextBookIndexSearch
Allyl Ligands

Introduction

Structure and Bonding

Spectroscopic Features of Allyl Ligands

Synthesis of Allyl Complexes

    Most syntheses of trihapto allyl complexes involve the synthesis of a monohapto complex which then displaces a ligand to give the trihapto form. Common methods for the synthesis of allyl complexes include:

  1. From an alkene via hydrogen attack on the metal (Eq 1). In the example below, note that if we then put the hydrogen on the other terminal carbon, we have accomplished an overall 1,3-hydrogen shift.

  2. Nucleophilic or electrophilic substitution at the metal using an allylic substrate (Eq 2)

  3. Oxidative addition of an allylic substrate to a low valent metal center (Eq 3).

  4. Protonation or insertion of a 1,3-diene complex (Eq 4).

  5. There are several other methods as well...

    synthetic examples

Reactions of Allyl Complexes

    All of Chapter 19 of Collman, Hegedus, Norton and Finke is dedicated to reactions of trihapto allyl complexes. Allyl complexes have a rich and useful chemistry, particularly in organic synthesis. Listed here are just a few of the most common reactions of allyl complexes:

  1. With nucleophiles (Eq 5). This is stereoselective if the metal is not attacked first. Attack occurs on the face opposite the metal and usually at the terminal carbon.

  2. With electrophiles.

  3. Insertion reactions (Eq 6).

  4. Reductive elimination (Eq 7)

    some examples of allyl reactions

dividing line

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This page was last updated Thursday, November 20, 2003
This document and associated figures are copyright 1996-2014 by Rob Toreki or the contributing author (if any) noted above. Send comments, kudos and suggestions to us by email. All rights reserved.