This document provides an introduction to organometallic chemistry including key concepts, examples, and objectives. Specifically, it discusses: - The objectives of understanding stability/reactivity, reaction mechanisms, and current literature in organometallic chemistry. - The background knowledge needed in organic, inorganic, and physical chemistry to understand organometallic chemistry. - Transition metal organometallics providing variety in structures and bonding types since transition metals can utilize multiple orbital types. - An example of the industrial synthesis of acetic acid using a rhodium catalyst, which requires understanding of electron counting and reaction types.

1. Organometallic Chemistry
Introduction to Organometallic
Compounds

2. Organometallic Chemistry
2
Course Objectives
By the end of this course, you should be able to:
• Make an educated guess about stability and reactivity of a given
compound, based on (a.o.) electron counting rules
• Propose reasonable mechanisms, based on "standard"
organometallic reaction steps, for many metal-catalyzed
reactions
• Use steric and electronic arguments to predict how changes in
reactants, metal or ligands affect the outcome of reactions
• Read a current research literature paper, understand and
explain its content and significance

3. Organometallic Chemistry
3
Useful Background Knowledge
Organometallic chemistry (CHEM 4140) is a 8th-level course because
it builds on:
• Organic chemistry: reaction mechanisms, primarily nucleophilic
and electrophilic attack
• Inorganic Chemistry: electronegativity; electron counting and
stability; properties of (transition) metals
• Physical chemistry: orbitals and MO theory; free energy, enthalpy
and entropy
You will (now and then) need this background to understand the
material or make assignments etc

4. • Organometallics play a vital role in the economy, with about
10 of the world’s top 30 chemicals being produced using
organometallic catalysts.
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5. • the history of organic chemistry was the accidental discovery that an
inorganic compound could be converted into an organic compound. It
was the German chemist Friedrich Wohler who, in 1828, synthesized
the inorganic compound ammonium cyanate, (NH4)(NCO), and found
that it spontaneously isomerized to urea, (NH2)2CO.
• Likewise, the synthesis was performed in 1760. It was in that year the
French chemist Louis Claude Cadet de Gassicourt mixed potassium
acetate with diarsenic trioxide and obtained “Cadet’s fuming liquid.”
This poisonous, oily red liquid with a garlic odor we now know to be
cacodyl oxide, As2(CH3)4O:
4CH3COOK + As2O3 As2(CH3)4O + 2 K2CO3 + 2 CO2
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6. • lists the key early discoveries in the history of organometallic
• chemistry together with the location of where each compound is
• first mentioned in this chapter.
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7. Introduction to Organometallic
Compounds
• Organometallic compounds straddle both inorganic and
organic chemistry. To be a member of this class, the
compound must contain at least one direct metal-to-carbon
covalent bond. The metal can be a transition, main group, or
f-group metal, and the term “metal” is often stretched to
include boron, silicon, germanium, arsenic, antimony,
selenium, and tellurium. The carbon-containing group(s) may
be carbonyl, alkyl, alkene, alkyne, aromatic, cyclic, or
heterocyclic. Unlike inorganic compounds, many
organometallic compounds are pyrophoric (spontaneously
flammable) and thermodynamically unstable.
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8. Organometallic Chemistry
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Elements of interest
Organic elements
Main group metals
Transition metals

9. However, it is the transition metal organometallic compounds that
provide us with richness and variety in their structures and bonding
types since transition metals can utilize s, p, and d orbitals in bonding.
- Each orbital type can either donate or accept electron density, and the
d orbitals on the metal are particularly well suited to interact with s and p
orbitals on the organic species .
- Unlike conventional transition metal complexes, the central metal atom
in an organometallic compound is often in a very low oxidation state.
organometallic compounds are of industrial importance as catalysts..
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10. Organometallic Chemistry
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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.

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Acetic Acid synthesis
Moderately complex
catalytic cycle:
H2O
HI CH3OH
CH3I
CH3COOH
CH3COI
Rh(CO)2I2
-
MeRh(CO)2I3
-
MeCORh(CO)I3
-
MeCORh(CO)2I3
-
CO

12. Organometallic Chemistry
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Acetic Acid synthesis
This cycle is known in considerable detail:
To understand it, you need to
be familiar with electron counting
and common reaction types
CO
Rh(CO) I
2 2
-
MeRh(CO) I
2 3
-
MeCORh(CO) I
2 3
-
MeCORh(CO)I3
-
CH I
3
CH COI
3
CH COOH
3
H O
2
HI CH OH
3
RhI
16 e
RhIII
18 e
RhIII
16 e
RhIII
18 e
oxidative
addition
insertion
reductive
elimination
ligand
binding

13. Organometallic Chemistry
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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.
(Ph3P)3RhCl
H2
O
OMe
Li
O
OMe
Li

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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 heterogeneous catalysis reactions such as
olefin hydrogenation and CO oxidation.
Organometallic compounds are used on a large scale as
precursors for generation of semiconductors (AlN, GaAs, etc).
Silicone rubbers are one of the few classes of organometallic
compounds used as "final products".

15. Naming Organometallic Compounds
• In addition to the general rules that we use to name simple
inorganic compounds or transition metal complexes, a few
supplementary rules are used to give additional information
about the nature of the bonding within the organometallic
molecule. First, we need to introduce a selection of the many
organic species that act as ligands in organometallic chemistry.
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16. The number of carbon atoms within an organic species that are directly
interacting with the metal is specified by the prefix η (eta). This is called
hapticity, : most ligands bond through one atom are described as
monohapto.
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17. The benzene molecule bonded to a metal via (a) two carbon atoms, (b) four
carbon atoms, and (c) all six carbon atoms.
Carbonyl ligands bridging (a) two metal centers and (b) three metal centers.
Species that can bridge two metal centers, such as carbonyl, halide, or
carbine ligands, are indicated by the prefix µ (mu)
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18.  Decide whether each of the following compounds should be described
as organometallic:
(a) B(CH3)3 (e) CH3COONa
(b) B(OCH3)3 (f) Si(CH3)4
(c) Na4(CH3)4 (g) SiH(C2H5)3
(d) N(CH3)3
 Write the formula for each of the following species.
(a) Methylbismuth Bi(CH3)3
(b) Tetraphenylsilicon (Ph4)4Si
(c) potassium tetraphenylboron K[B(ph4)]
(d) Methyllithium LiCH3
(e) ethylmagnesium chloride C2H5MgCl
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19. Name each of the compounds.
Sketch the structures of the following compounds:
(a) Li4(CH3)4 (d) (CH3)3SnF
(b) Be(CH3)2 (e) (CH3)3PbCl
(c) B(C2H5)3
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