1. +
In Search of Pincer Derivatives for
Dehydrogenation Catalysts
Laura Chamness, Kendrich Hatfield, Kyle
Mehringer, and Clare Nolan with Dr. Seyler

2. +
Catalytic Cycle

3. +
Formation of a Catalyst
 [(COE)2IrCl]2 dimer is the source of Iridium for our synthesis
 Dimer + pincer ligand (tBuPCP) -> tBuPCPIrHCl
 Superhydride converts to tetrahydride complex
c

4. +
Pincer Ligands
Various organic
groups
• iso-Propyl
• tert-Butyl
• Adamantyl
PCP PCOP
POCOP

5. +
Synthesis of PCOP Pincer

6. +
Synthesis of the POCOP Pincer
1a, b
1a
1b
1. THF, 2.1 equiv. NaH
1 hr reflux
2. 1 equiv. tBu2PCl
12 hr r.t.
3. 1 equiv. iPr2PCl
1 hr reflux
MeO MeO
(iPr)2P
MeO

7. +
Synthesis of tBu4POCOPIrHCl
Iridium Dimer
Pincer
tBu4POCOPIrHCl

8. +
Synthesis of the Catalyst
tBu4POCOPIrH2
O
O

9. +
Catalysis

10. +
Results

11. +
Results
COE
COA

12. +
Results
“IrHCl”
“IrH2”

13. +
Results
COE
COA

14. +
Activation Energy
• Activation energy shows how much energy is
needed for the reaction
• Lower activation energy indicates an “easier”,
quicker reaction
• Dissociation intermediates modeled and energies
calculated to illustrate the activation energy

15. +
0
20
40
60
80
100
120
140
160
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5
Std. E
(kJ/mol)
Bond length (angstroms))
tBuPCOPIrH2 cisH ethylene dissociation
Activation
Energy
Modeling Dissociation of “Used”
Fuel (Propene)

16. +
Complete Energy Diagrams
• Models the complete Energy change of the catalysis
reaction
• Information obtained via dissociation modeling and
transition state calculations on Spartan software
• Graphs are fun!

17. -100
-50
0
50
100
150
200
250
300
0 1 2 3 4 5 6 7 8
RelativeEnergy(kJ/mol)
"Time"
iPr Catalyst Energy Diagram
PCP
PCOP

19. +

20. A “Pinsir”!
tBu tBu
Ad
Ad Ir
H-H

21. +
Thank You
 National Science Foundation
 Dr. Bower
 Dr. Seyler
 … and Abu