Knowledge Bank

The microwave spectra, from 8-40 Ge, of 2-chloroethanol, 2-bromoethanol, and 2-fluoroethanol$\mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}$ have been investigated in order to determine the influence of a proposed intramolecular hydrogen bond in these molecules. The gauche form of each molecule has been found and analyzed. 2-chloroethanol has been by far the most extensively investigated, with nine isotopic combinations having been analyzed to yield an *** structure (except for the methylenic hydrogens). The $\mathrm{<mrow\; data-mjx-texclass="ORD">79</mrow>}$Br and $\mathrm{<mrow\; data-mjx-texclass="ORD">81</mrow>}$Br species of bromoethanol have been assigned, and work on their hydroxylly deuterated species is in progress. Major structural results are a longer OH bond than in ethanol (at least for the chloro compound) and a surprisingly similar (CCX) (CCO) dihedral angle of $63\circ$ for $X=Cl,Br,F$. Quadrupole coupling constants have been obtained with the aid of the analysis of second-order effects. Excited states of three different modes of vibration (CC torsion, CCCl bend, CO torsion) have been assigned in the chloro compound, and, from rough intensity measurements, were found to have vibrational energies of approximately $160,300,300cm-1$. This research was supported in part by a grant to Harvard University by the National Science Foundation. R.G. Azrak is an NIH Predoctoral Fellow. $\mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}$ K.S. Buckton, ``Symposium on Molecular Structure and Spectroscopy,'' Columbus, 1965, Paper Y6.