Knowledge Bank

The microwave spectrum of iso-butenyl chloride (1-chloro-2-methyl-2-propene) has been studied in order to investigate rotational isomerism about the $C1-C2$ bond. It has been found that the spectrum is dominated by a-type transitions of a rotamer which has the $C - $Cl bond gauche with respect to the ethylenic group. A number of weaker lines have been tentatively assigned for the cis rotamer. Spectral assignment was assisted greatly by the use of radio frequency microwave double resonance techniques. Rotational constants have been determined for $\mathrm{<mrow\; data-mjx-texclass="ORD">35</mrow>}Cl$ and $\mathrm{<mrow\; data-mjx-texclass="ORD">37</mrow>}Cl$ isotopic species and structural parameters derived from these data will be compared with those for related molecules.