1. Application of Organometallic Chemistry – Breaking the Inert C-H Bond
Literature Special Topic
Date
Created by [John Lee, University of Tennessee Chattanooga, and posted on VIPEr ( on [July 16, 2012], Copyright [July, 16, 2012]. This work is licensed under the Creative Commons [Attribution-NonCommercial-ShareAlike 3.0 Unported] License. To view a copy of this license visit

2. You want to break which bond!
Example Organic Molecules
-Why do we draw line structures for
Organic molecules?
-High bond energy
methane 100 kcal/mol
benzene 110 kcal/mol
-High pKa
on the order of >40
This slide uses line structures vs. full organic structure to remind the student that we normally do not draw the C-H bond out of convenience, but that convenience is because the C-H bond is unreactive (in most cases).
An astute student could ask “But hexane has three different C-H bonds?” The answer is beyond the scope but you could direct them to studies that have shown H/D exchange reactions show all bonds are accesiblie (kinetically) but the final thermodynamic product is the stronger methyl C-H bond.
**,but…Nature uses the C-H bond: See methane monooxygenase and vitamin-b12

3. In organic chemistry…. Generic Substitution Reaction (SN1 shown)
A very brief (possibly too brief?) reminder that in organic chemistry the reaction usually involves some sort of reactive functional group.
Leaving Groups (LG)
TsO-, NH3 > I-, H2O > Br- > Cl- > HO-, NH2-, RO-
Carey, F. A. Organic Chemistry, 4th ed. 2001, McGraw-Hill, Chapter 8.

4. In organometallic chemistry….
Cross-Coupling Reactions
This slide could be removed, and is very busy if used. To remind students of the Pd cross coupling reactions that were recently awarded a Nobel Prize.
Heck, R. F.; Negishi, E.; Suzuki, A. palladium catalyzed cross couplings in Organic Synthesis: Great Art in a Test Tube.
(March 17, 2011).
but wait I said C-H not C-X activation?

5. If it ain’t broke why fix it?
-Nearly everything comes from coal, oil or natural gas
Coal: 1,000 – 2,000 years
Oil: 50 – 150 years
Natural gas: 207 – 590 years
-However this is not sustainable for population growth
Why?
-We are a good (optimistic) years from solar
-For the interim time we should use our resources to the
best of our ability
How?
The why are we interested in this slide. I took a sustainable future approach.
Lewis, N. S.; Nocera, D. G. Proc. Nat. Acad. Sci. 2006, 103,

6. How? Rationale design and synthesis
Metal Ligands
C-donor,
N-donor,
O-donor,
P-donor,
or S-donor etc…
Most complexes that do C-H activation must by synthesized. This is a fun slide using a blender instead of the round bottom flask. It ends with, remember it is about how the ligands affect the d orbitals.
What it is really all about!
Shriver and Atkins Inorganic Chemistry, 5th ed. 2001, Freeman, Chapter 1.

7. Some typical mechanisms
Spend some time here going through each one. I tell the students that we will skip the last two. As a side note the figure on this slide is a figure I generated and did not come from the text of the paper. If you would like the chemdraw in order to make edits please me and I will send the file.
Labinger, J. A.; Bercaw, J. E. Nature 2002, 417,

8. Example 1: Oxidative addition
Qualitative MO Diagram
-The metal’s oxidation state increases by two units
Must be accessible
-Requires an electron rich metal
Low oxidation state
Electron donating ligands
-The metal’s coordination # increases by two
-Many d8 metals meet these criteria:
Primarily RhI and IrI
Sometimes PdII and PtII
Both words and a very qualitative MO diagram (only showing the C-H – M interaction) is shown. Highlight the pi interaction.

9. Example of oxidative addition: Alkane dehydrogenation
An example of oxidative addition in catalysis is given. This is taken from the Nature paper; however, see references from A. Goldman for further information. I used propane as a theoretical example.

10. Example 2: s-Bond metathesis
Qualitative MO Diagram
-Early transition metals that do not have a n+2
oxidation state available
-Late transition metals that do not have an
accessible n+2 oxidation state
-Many d0 metals meet these criteria:
For example, ScIII, ZrIV, TaV
Both words and a very qualitative MO diagram (only showing the C-H – M interaction) is shown. Highlight there is no pi interaction because there are no d electrons.

11. Example of s-bond metathesis: Hydromethylation of propylene
An example of sigma bond metathsis in catalysis is given. This is taken from above cited paper..
Sadow, A. D.; Tilley, T. D. J. Am. Chem. Soc. 2003, 125,

12. Example #3: Electrophilic substitution
Qualitative MO Diagram
A very qualitative MO diagram (only showing the C-H – M interaction) is shown. Highlight that this is usually involves later transition metals where the d orbitals have dropped in energy. A chance to quiz on periodic trends, and an example of a crystal structure is given for a more advanced topic
Milstein, D. et al. J. Am. Chem. Soc. 1998, 120,

13. Example of electrophilic substitution: Methane oxidation
An example of electrophilic mechanism in catalysis. See the referenced paper for more information
Periana, R. A.; Taube, D. J.; Gamble, S.; Taube, H.; Satoh, T; Fuji, H Science 1998, 280,

14. C-H Functionalization: A challenge
C-C Bond Formation – Olefin Insertion
This last slide is a deep thought question. Many C-C bond forming reactions in organometalic chemistry involve olefin insertion; however, olefin insertion prefers somewhat electron deficient metals (but not so much to do polymerization) and oxidative addition prefers electron rich metals.
Foley, N. A.; Lee, J. P.; Ke, Z.; Gunnoe, T. B.;
Cundari, T.. R. Acc Chem. Res. 2009, 42,