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The crystal structure of perchlorocyclooctatetraene (y-C8Cl8) has been investigated and solved by direct methods. As a result of the cry stal structure analysis the constitution of the molecule, derived by Helm, Roedig, Smith and West from spectroscopic measurements, has been found to be true

The crystal structure of perchlorobenzocyclobutene (ß-C8C\ 8) has been investigated and solved by means of the unusual Patterson projection along the axis of twinning, by which the space group had been determined. As a result of the crystal structure analysis the constitution of the molecule, derived by J . Brandmüller and E. Ziegler from spectroscopic measurements, has been found to be true.