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Protonated Ethylene Carbonate: A Highly Resonance-Stabilized Cation
Stefanie Beck1, Christoph Jessen1, Andreas J Kornath1
1Department of Chemistry, Ludwig-Maximilians-Universität München, Butenandstr. 5-13, 81377, München, Germany.
Chemistryopen
|November 25, 2021
Summary
Researchers synthesized protonated ethylene carbonate using a superacidic system. The crystal structure revealed a planar carbonate group with a delocalized 6π-electron system, indicating significant resonance stabilization.
Area of Science:
- Inorganic Chemistry
- Physical Chemistry
- Crystallography
Background:
- Ethylene carbonate is a common organic solvent.
- Superacidic systems like HF/SbF5 are potent protonating agents.
- Understanding the structure and bonding of protonated species is crucial in chemistry.
Purpose of the Study:
- To synthesize and characterize the salt of protonated ethylene carbonate.
- To investigate the structural and electronic properties of the protonated ethylene carbonate cation.
- To explore the bonding characteristics within the carbonate moiety.
Main Methods:
- Synthesis of protonated ethylene carbonate by reacting ethylene carbonate in HF/SbF5 at low temperatures.
- Single-crystal X-ray structure analysis to determine the crystal structure.
- Theoretical investigations to study the electronic structure of the cation.
Main Results:
- The crystal structure of [C3H5O3][Sb2F11] was determined.
- A planar CO3 moiety with nearly equal CO bond lengths was observed in the protonated ethylene carbonate cation.
- Theoretical calculations revealed a delocalized 6π-electron system within the CO3 group, indicating resonance stabilization.
Conclusions:
- Protonation of ethylene carbonate leads to a planar carbonate structure with significant electron delocalization.
- The observed resonance stabilization is a key feature of the protonated ethylene carbonate cation.
- This study provides insights into the chemistry of superacid-promoted reactions and the electronic structure of organic cations.
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