Intramolecular hydrogen bonding: The molecular structure and conformations of 3-butyn-1-ol

The molecular structure and conformational composition of 3-butyn-1-ol have been studied by the gas electron diffraction method and by ab initio calculations. The preferred conformation is gauche, and the experimental data are in accordance with a conformational mixture of 85 +/- 10% gauche and 15 +/- 10% anti. The most important geometric parameters were determined to be r(a)(C=C): 1.217(1) Angstrom, r(a)(C-2-C-3): 1.469(1) Angstrom, r(a)(C-1-C-2): 1.536(2) Angstrom, r(a)(C-O): 1.414(1) Angstrom, LC-C-C-G: 111.6(6)degrees, angle C-C-O-G: 113.9(6)degrees, theta(-C-C-)(G): 60.2(1.6)degrees. The values in parentheses are standard deviations. The experimental data are in accordance with a non-linear H-C=C-C fragment in the gauche conformer.