A study of the conformational isomerism of 1-Iodobutane by microwave spectroscopy

The rotational spectrum of 1-iodobutane was measured in a frequency range of 7-13 GHz, revealing a dense set of rotational transitions. Over 400 of the observed transitions were assigned to three different low energy conformational isomers. A previous low resolution microwave study\footnote{Steinmetz, W. E.Hickernell, F.Mun, I. K.Scharpen, L. H. \textit{J. Mol. Spectrosc.} \textbf{1977}, \textit{68}, 173-182.} of 1-haloalkanes, including 1-iodobutane, confirmed that the three conformers present are the anti-anti, gauche-anti, and gauche-gauche species. From this high resolution study, the complete nuclear quadrupole coupling tensor of iodine was determined for each conformer. Rotational, centrifugal distortion, nuclear spin-rotation coupling constants will be discussed. Nuclear quadrupole coupling constants will also be presented and compared to other iodoalkane species. \begin{wrapfigure}{r}{0pt} \includegraphics[scale=0.73]{three_conformers_MP2_002.eps} \end{wrapfigure} \vspace{2in} \mbox{