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Rotational Spectra of Seven Conformational Isomers of 1-Hexene



Gerald T. Fraser, R D. Suenram, C Lugez


The rotational spectra of 7 of the expected 13 conformational isomers of 1-hexene have been measured and assigned at a rotational temperature of 1 symmetry, as verified by the observation of a, b, and c-type electric-dipole transitions. The remaining conformer has Cs symmetry, consistent with its small inertial defect, {Δ}{identical with} Icc - Ibb - Iaa = -12.65 u 2, and the observation of only a and b-type transitions. Here, Iaa is the moment of inertia of the conformer about its α-principal axis. The inertial defects determined for the seven conformers range from -12.65 u 2 to -51.29 u 2. Both the molecular mechanics and ab initio calculations indicate the observed conformers are associated with the seven lowest energy conformational minima of 1-hexene. The ab-initio-calculated energy difference between the lowest and highest energy conformers observed is 326 cm-1, including vibrational zero-point contributions, indicating that the conformational temperature is not equilibrated with the approximately 2 K rotational temperature of the molecular-beam expansion.
Journal of Physical Chemistry A
No. 6


computational chemistry, conformer, hexene, microwave spectroscopy, molecular beam spectroscopy, molecular modeling, rotational spectroscopy


Fraser, G. , Suenram, R. and Lugez, C. (2000), Rotational Spectra of Seven Conformational Isomers of 1-Hexene, Journal of Physical Chemistry A (Accessed July 18, 2024)


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Created February 1, 2000, Updated February 17, 2017