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Charge distribution and aromaticity in protonated urazole
Alexander Nitzer1, Christoph Jessen1, Andreas J Kornath1
1Department of Chemistry, Ludwig-Maximilians University of Munich, Butenandtstrasse 5-13, 81377 Munich, Germany. Alexander.nitzer@cup.uni-muenchen.de.
Chemical Communications (Cambridge, England)
|February 24, 2025
Summary
Urazole
Area of Science:
- Organic Chemistry
- Physical Chemistry
- Computational Chemistry
Background:
- Urazole is a heterocyclic compound with potential applications in various chemical fields.
- Understanding the protonation behavior of urazole is crucial for predicting its reactivity and stability in acidic environments.
- Previous studies have explored the chemistry of related compounds, but the specific protonation of urazole in superacids requires further investigation.
Purpose of the Study:
- To investigate the protonation of urazole in superacidic media.
- To characterize the mono- and diprotonated species of urazole using various spectroscopic and crystallographic techniques.
- To compare the protonation behavior of urazole with that of parabanic acid.
Main Methods:
- Reaction of urazole in different superacidic media.
- Isolation and characterization of protonated urazole species using Raman spectroscopy, NMR spectroscopy, and single crystal X-ray diffraction.
- Computational analysis including quantum chemical calculations, electrostatic potential mapping, Natural Population Analysis (NPA) charges, and Nucleus-Independent Chemical Shift (NICS(0)) calculations.
Main Results:
- Mono- and diprotonated urazole species were successfully isolated and structurally characterized.
- Quantum chemical calculations provided insights into charge distribution and localization within the urazole cations.
- Aromaticity of urazole and its protonated forms was assessed using NICS(0) calculations.
- Comparative analysis revealed similarities and differences in the protonation patterns of urazole and parabanic acid.
Conclusions:
- The study successfully elucidated the protonation sites and structures of urazole in superacidic conditions.
- The findings contribute to a deeper understanding of heterocyclic compound behavior in extreme acidic environments.
- The comparison with parabanic acid offers valuable insights into the structure-reactivity relationships of related cyclic compounds.
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