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The Microwave Spectrum of 1-Chloro-2-methylpropene
1Institut für Physikalische Chemie, Rheinisch-Westfälische Technische Hochschule (RWTH), Templergraben 59, Aachen, 52056, Germany
Journal of Molecular Spectroscopy
|July 6, 2000
Summary
High-resolution microwave spectroscopy of 1-chloro-2-methylpropene reveals precise molecular properties. Ab initio calculations complement experimental data, providing insights into internal rotation potential barriers and interaction constants.
Area of Science:
- Molecular spectroscopy
- Quantum chemistry
Background:
- Previous studies of 1-chloro-2-methylpropene used lower-resolution techniques.
- Detailed understanding of internal rotation in substituted alkenes is crucial.
Purpose of the Study:
- To measure the rotational spectrum of 1-chloro-2-methylpropene with very high resolution.
- To determine accurate molecular parameters, including rotational constants, centrifugal distortion constants, and quadrupole coupling tensors.
- To investigate the potential barriers of methyl group internal rotation and compare experimental results with theoretical calculations.
Main Methods:
- Pulsed molecular-beam Fourier transform microwave (MB-FTMW) spectroscopy.
- Ab initio quantum chemical calculations.
Main Results:
- Accurate rotational constants and centrifugal distortion constants were determined.
- Complete (35)Cl and (37)Cl quadrupole coupling tensors were obtained.
- Experimental V(3) hindering barriers for both methyl rotors were determined.
- Ab initio calculations provided a potential surface for internal rotation, allowing comparison with experimental barriers.
Conclusions:
- The high-resolution MB-FTMW data significantly improve upon previous spectroscopic observations.
- The combination of experimental and theoretical methods provides comprehensive information on the internal dynamics of 1-chloro-2-methylpropene.
- This study offers insights into higher potential terms and top-top interaction constants for the methyl rotors.
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