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Protocol for the Synthesis of Ortho-trifluoromethoxylated Aniline Derivatives
Published on: January 19, 2016
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The ortho-benzyne cation is not planar
D Kaiser1, E Reusch, P Hemberger
1Institute of Physical and Theoretical Chemistry, University of Würzburg, Am Hubland, D-97074 Würzburg, Germany. ingo.fischer@uni-wuerzburg.de bernd.engels@uni-wuerzburg.de.
Physical Chemistry Chemical Physics : PCCP
|January 20, 2018
Summary
This study revises the ionization energy of ortho-benzyne, revealing its cation has a twisted geometry, not planar. Advanced computations and photoelectron spectroscopy confirm new energy values, challenging previous findings.
Area of Science:
- Physical Chemistry
- Quantum Chemistry
- Spectroscopy
Background:
- Previous studies on ortho-benzyne photoionization yielded ambiguous results regarding its cation's geometry and ionization energy.
- Doubts were raised about the accuracy of earlier photoelectron spectra due to potential side products and computational limitations.
Purpose of the Study:
- To accurately determine the ionization energy and cation geometry of ortho-benzyne.
- To resolve discrepancies in existing experimental and theoretical data for ortho-benzyne.
Main Methods:
- Photoionization of ortho-benzyne generated via pyrolysis.
- Photoion mass-selected threshold photoelectron (ms-TPE) spectroscopy using synchrotron radiation.
- High-level ab initio computations, including CASPT2(11,14), to investigate cation structure and energetics.
- Franck-Condon simulations for spectral assignment.
Main Results:
- The ortho-benzyne cation exhibits a twisted C2 geometry, not a planar C2v structure.
- A revised adiabatic ionization energy (IEad) of 9.51 eV was determined experimentally and computationally.
- CASPT2 computations accurately described the cation's electronic states, unlike density functional theory methods for excited states.
Conclusions:
- The ionization energy of ortho-benzyne needs revision based on this comprehensive study.
- Accurate theoretical methods are crucial for interpreting photoelectron spectra and determining molecular properties.
- This work clarifies the electronic structure and energetics of the ortho-benzyne cation.
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