Organometallic Chemistry between organic and inorganic

Peter H.M. Budzelaar

Course Roadmap
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A real example: the Monsanto Acetic Acid process
Introduction: what is organometallic chemistry, and why should you care?
Electron counting: the basis for understanding structure and reactivity
An overview of Main-group and Transition metal chemistry
Main group metal chemistry and "Umpolung"
Intermezzo: characterization of organometallic compounds
Transition metal chemistry: overview of common ligands
Ligand substitution
Insertion and elimination
Oxidative insertion and reductive elimination
More exotic steps
Your own presentations
Applications in catalysis

2

Organometallic Chemi

Example: Acetic Acid synthesis
Acetic acid is an important industrial chemical.
The traditional synthesis uses bio-oxidation of ethanol obtained via fermentation: C6H12O6  2 C2H5OH + 2 CO2
C2H5OH + O2  CH3COOH + H2O
This is not a clean and efficient process!
Industrial acetic acid synthesis:
CH3OH + CO  CH3COOH
Catalyzed by a rhodium complex.

3

Organometallic Chemi

Acetic Acid synthesis
CH3COOH

HI

CH3OH

Moderately complex catalytic cycle:
CH3COI

H2O

CH3I

Rh(CO)2I2-

MeCORh(CO)2I3-

CO

4

MeRh(CO)2I3-

MeCORh(CO)I3-

Organometallic Chemi

Acetic Acid synthesis
HI

This cycle is known in considerable detail:

CH3OH

CH3COOH

H2O
CH3I
CH3COI

oxidative addition Rh(CO)2I2-

To understand it, you need to be familiar with electron counting and common reaction types

RhI
16 e

reductive elimination MeRh(CO)2I 3MeCORh(CO)2I3

-

ligand binding CO

5

RhIII
18 e

RhIII
18 e

RhIII
16 e
MeCORh(CO)I3

insertion
-

Organometallic Chemi

What is organometallic chemistry ?
Strictly speaking, the chemistry of compounds containing at least one metal-carbon bond.
Metal hydrides are often included, H being considered as the
"smallest organic group" (as in propyl, ethyl, methyl, hydride).
Metal-carbon bonds are often formed temporarily or potentially, so in practice many compounds are included that do not actually contain metal-carbon bonds.

H2
(Ph3P)3RhCl

OMe
Li

6

O

OMe

Li
O

Organometallic Chemi

Why should you care ?
Organometallic chemistry is the basis of homogeneous catalysis, which is the method of choice for clean and efficient synthesis of fine chemicals, pharmaceuticals and many larger-scale chemicals. Many plastics (polythene, polypropene, butadiene rubber, ...) and detergents are made via organometallic catalysis.
Organometallic chemistry is also the basis for understanding important steps in