Beschreibung:
<jats:title>Abstract</jats:title>
<jats:p>In order to obtain information about the slow rotation of methyl groups, the 1H NMR spectra of 9-t-butylethenoanthracene and 9-t-butyltriptycene derivatives were measured at very low temperatures. It was found that the signals of the two methyls of the t-butyl group in these compounds show a considerable line broadening at low temperatures, and it was made clear that the rotation of the methyl groups in these compounds is strongly restricted.</jats:p>