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Radical-promoted Stone-Wales rearrangements
Roger W Alder1, Jeremy N Harvey
1School of Chemistry, University of Bristol, Cantock's Close, Bristol, UK BS8 1TS. rog.alder@bris.ac.uk
Journal of the American Chemical Society
|February 26, 2004
Summary
The Stone-Wales rearrangement mechanism was studied using computational methods. A radical-promoted pathway is more likely than a unimolecular one for complex polycyclic aromatic hydrocarbons.
Area of Science:
- Computational Chemistry
- Organic Chemistry
- Materials Science
Background:
- The Stone-Wales rearrangement is a key reaction in modifying polycyclic aromatic hydrocarbons (PAHs).
- Understanding the mechanism is crucial for designing novel carbon materials and predicting reactivity.
Purpose of the Study:
- To elucidate the mechanism of the Stone-Wales rearrangement for bifluorenylidene to dibenzo[g,p]chrysene.
- To investigate the feasibility of radical-promoted pathways for complex PAHs and fullerenes.
Main Methods:
- Density functional calculations using the B3LYP/6-31G(d) level of theory.
- Analysis of activation energies for proposed reaction pathways.
Main Results:
- A radical-promoted mechanism with a sequence of homoallyl-cyclopropylcarbinyl rearrangement steps accurately explains experimental observations.
- Unimolecular mechanisms exhibit impractically high activation energies.
- Radical-promoted pathways remain favorable for diindeno[1,2,3,4-defg;1',2',3',4'-mnop]chrysene and C(60), despite increased activation energies due to steric hindrance.
Conclusions:
- Radical-promoted mechanisms are essential for understanding Stone-Wales rearrangements in complex PAHs.
- Computational studies provide valuable insights into reaction pathways and energetics for carbon-based materials.
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