E. Cox
Sep 1, 1928
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0
Influential Citations
82
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Quality indicators
Journal
Nature
Abstract
BY means of X-ray measurements upon single crystals, using the rotation method, I have been able to determine the unit cell of benzene. The cell is simple orthorhombic, of dimensions a=7.44 A., b=9.65 A., and c=6.81 A. at −22° C., and contains four molecules. As a result of the examination of about one hundred crystal planes, the space group was found to be Ql5h (orthorhombic bipyramidal). From this it can be shown that in the crystal the molecule has a centre but no planes of symmetry. Taking a standard molecule at a corner of the cell, the three derived molecules are situated at the centres of the cell faces. This pseudo-face-centred arrangement accounts both for the fact that the plane (111) gives the strongest X-ray reflections, and also for the bipyramidal habit of benzene crystals.