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Conformational Panorama of Cycloundecanone: A Rotational Spectroscopy Study
Valerie W Y Tsoi1, Ecaterina Burevschi1, Shefali Saxena1
1Department of Chemistry, King's College London, London SE1 1DB, United Kingdom.
Chirped-pulse microwave spectroscopy revealed nine distinct conformations of cycloundecanone. The most stable conformer, influenced by specific hydrogen interactions, dominates the spectrum.
Area of Science:
- Physical Chemistry
- Molecular Spectroscopy
- Computational Chemistry
Background:
- Medium-sized cyclic ketones present complex conformational challenges.
- Understanding molecular structure is crucial for predicting chemical properties.
Purpose of the Study:
- To elucidate the conformational landscape of cycloundecanone.
- To identify and characterize the various conformers present.
- To determine the factors governing conformational preferences.
Main Methods:
- Chirped-pulse Fourier transform microwave spectroscopy was employed.
- Computational calculations were used for theoretical analysis.
- Rotational constants and transition types were compared for identification.
Main Results:
- Nine distinct conformations of cycloundecanone were observed.
- The most abundant conformer was identified and studied using 13C isotopologues.
- Partial substitution and effective structures were determined for the dominant conformer.
- The most abundant conformer is significantly more stable than others.
Conclusions:
- Conformational preferences in cycloundecanone are dictated by transannular H···H and eclipsed HCCH interactions.
- The study provides a detailed understanding of the conformational dynamics of medium-sized rings.
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