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The 1,2,3-tridehydrobenzene triradical: 2B or not 2B? The answer is 2A!
Lucas Koziol1, Michael Winkler, K N Houk
1Department of Chemistry, University of Southern California, Los Angeles, California 90089-0482, USA.
The Journal of Physical Chemistry. A
|May 24, 2007
Summary
Computational methods reveal the electronic structure of 1,2,3-tridehydrobenzene. The (2)A(1) state is the ground state, nearly degenerate with the (2)B(2) state, with a weak meta radical bond.
Area of Science:
- Computational Chemistry
- Quantum Chemistry
- Spectroscopy
Background:
- 1,2,3-tridehydrobenzene is a highly reactive intermediate.
- Understanding its electronic states is crucial for reaction mechanism studies.
Purpose of the Study:
- Investigate the molecular and electronic structure of 1,2,3-tridehydrobenzene.
- Determine the ground electronic state and bonding characteristics.
Main Methods:
- Ab initio computational chemistry methods.
- Calculation of electronic states, energy gaps, and vibrational frequencies.
- Comparison with experimental infrared (IR) transitions.
Main Results:
- Two lowest electronic states, (2)B(2) and (2)A(1) doublet states, were identified.
- Adiabatic energy gap between states is small (0.7-2.1 kcal/mol), favoring the (2)A(1) state.
- Calculated vibrational frequencies and anharmonic corrections align with experimental IR data.
Conclusions:
- The (2)A(1) state is assigned as the ground state of 1,2,3-tridehydrobenzene.
- A weakly bonding distance of 1.67-1.69 Å between meta radical centers was determined.
- Computational findings support experimental observations of the triradical's structure.
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