The crystalline structure of benzene

Abstract

In a previous communication the writer gave the preliminary results of an investigation on the structure of solid benzene. It may be recalled that the unit cell was found to have the following dimensions at —22° C. ; a = 7·44, b = 9·65, c = 6·81 Å. U., while the space-group was determined as Q_h ¹⁵ (orthorhombic bipyramidal). The unit cell contains four molecules, the molecules being centro-symmetrical. Since the publication of these results a certain amount of information has been obtained by other investigators. Bruni and Natta took powder photographs of benzene which confirmed the above values of the cell-dimensions; this is very satisfactory, since previous workers (Broomé and Eastman) had obtained axial ratios which did not agree particularly well with each other’s or with the writer’s. Mrs. Lonsdale has shown that in hexamethylbenzene the benzene ring is planar, the diameter of the atoms being 1·42 Å. U. More recently she has examined hexachlorobenzene, and although in this case the investigation did not yield quite such definite results, it was shown that if the ring is planar then again the diameter of the atoms must be 1·42 Å. U.