J. Fournier, R. Bohn, H. Michels
Sep 1, 2008
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Influential Citations
4
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Journal
Journal of Molecular Spectroscopy
Abstract
Abstract From its microwave rotational spectrum, 6-methyl-3-heptyne (MHept, ethyl isobutyl acetylene) has been characterized in two conformations of Cs and C1 symmetry with the opposing alkyl groups arranged syn-eclipsed or nearly so about the C C axis. The dominant interaction determining the dihedral angle about the C C axis is the small dispersion attraction between the separated ethyl and isobutyl groups. The three lowest energy conformers of 2-methylpentane (MPane), MHept without C C, have been characterized from their microwave spectra. MPane has more conformations than MHept because the C3 C4 bond in MPane has a substantial ethane-like barrier supporting gauche and anti conformations while MHept’s tiny C2 (C3 C4) C5 torsional barrier has only a single minimum. Ab initio calculations of both compounds at the MP2/6-311+G(d,p) level agree with the experimental results.