MICROWAVE, ELECTRON-DIFFRACTION, AB-INITIO AND IR STUDY OF 2-CYCLOPROPYLETHANOL

The structure and conformation of 2-cyclopropylethanol have been studi ed by microwave spectroscopy, gas electron diffraction, gas-phase infr ared spectroscopy and by theoretical ah initio calculations at the 6-3 1G* level of theory. The microwave spectra of the parent and one deut erated species (hydroxyl group) have been investigated in the 26.5 39. 5 GHz spectral region at - 15-degrees-C. One conformer was assigned. T his rotamer is stabilized by an intramolecular hydrogen bond formed be tween the hydrogen atom of the hydroxyl group and the pseudo-pi electr ons on the outside of the nearest C-C edge of the cyclopropyl ring. Th e identified conformer is shown to be present in a concentration of 10 -30% of the total. The electron diffraction data are in accordance wit h the presence of three 2-cyclopropylethanol conformers, each being ch aracterized by the dihedral angles associated with the C2-C3, C1-C2 an d C1-O1 bonds, as follows: G + /G + /G-(48.6 %); G + /G -/A (19.7 %); G + /A/A (31.7 %). The most abundant conformer is the one that was ide ntified from the microwave spectrum. The observed conformational compo sition is in satisfactory agreement with that deduced from the energie s of the conformers studied by the ab initio calculations.