The Crystal Structure of Cubic Cyctohexane, Part 1

Timmermans2) has shown that a number of molecular crystals which have low entropy of fusion possess high crystallographic symmetries, plasticity, specific heats, dielectric ptoperties, etc. comparable with their liquid state. He considers such a state of aggregation as an intermediate phase between liquid and crystalline states and calls them •gplastic crystals•h. X-ray examination on these plastc crystals including cubic pentaerythritol **) C(CH2OH)4, tetranitromethane3) C(NO2)4 and cyclohexanol4) C6H11OH has now been extended to cubic cyclohexane C6H12 (m.pt. 6.3•Ž) which may be taken as a good example of such crystals. The methods for preparing single crystals and X-ray photographs were almost the same as in the cases of tetranitromethane and cyciohexanol, except a slight change of cooling device. The unit was found to be cubic face-centerd, a=8.73A.,containing four molecules in it. The possible space group was given as T2d-F48m, O3-F43 or O5h -Fm8m. From the same symmetry consideration as was done in the cases of the