Vibrational assignment and structure of trifluorobenzoylacetone. A density functional theoretical study
Sayyed Faramarz Tayyari1, Mohammad Vakili, Abdo-Reza Nekoei
1Department of Chemistry, University of Ferdowsi, Mashhad 91775-1436, Iran. Tayyari@ferdowsi.um.ac.ir
Density functional theory (DFT) calculations reveal that 4,4,4-trifluoro-1-phenyl-1,3-butanedione (TFBA) exists as a mixture of cis-enol conformers. TFBA exhibits a hydrogen bond strength intermediate between trifluoroacetylacetone and acetylacetone, but weaker than benzoylacetone.
Area of Science:
- Computational Chemistry
- Molecular Spectroscopy
- Organic Chemistry
Background:
- Beta-diketones are versatile ligands in coordination chemistry.
- Understanding the conformational preferences and stability of beta-diketones is crucial for their applications.
- Trifluorobenzoylacetone (TFBA) is a fluorinated beta-diketone with potential applications in catalysis and materials science.
Purpose of the Study:
- To investigate the molecular structure and vibrational frequencies of TFBA using computational methods.
- To compare the properties of TFBA with related compounds like benzoylacetone (BA), acetylacetone (AA), and trifluoroacetylacetone (TFAA).
- To elucidate the conformational stability and hydrogen bonding characteristics of TFBA.
Main Methods:
- Density Functional Theory (DFT) calculations were employed to model the molecular structure and vibrational spectra.
- Natural Bond Orbital (NBO) theory was used to analyze molecular stability and hydrogen bond strength.
- Calculated results were compared with experimental spectroscopic data.
Main Results:
- DFT calculations suggest the coexistence of two stable cis-enol conformers of TFBA in comparable proportions.
- The energy difference between these conformers is minimal (0.96 kcal/mol).
- The hydrogen bond strength in TFBA was found to be intermediate between TFAA and AA, and weaker than BA.
Conclusions:
- TFBA exists as a mixture of closely related cis-enol conformers.
- The hydrogen bonding in TFBA is weaker than in benzoylacetone, influencing its molecular stability and reactivity.
- Computational and spectroscopic methods provide valuable insights into the structure-property relationships of fluorinated beta-diketones.
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