SPACE-GROUPS RARE FOR ORGANIC STRUCTURES .3. SYMMORPHISM AND INHERENTMOLECULAR SYMMETRY

To a close approximation, the relative frequency of the space groups o f molecular organic compounds is determined by ease of packing. When t he molecules are in general Wyckoff positions, the relative frequency anti-correlates with the degree of symmorphism. Somewhat different con siderations apply if the molecule possesses and uses some inherent sym metry (1BAR, 2, m, 2/m, 222, mm,...) (sic) Organic Chemical Crystallog raphy. New York: Consultants Bureau]. The observed frequencies are ana lysed in the light of the degree of symmorphism and molecular symmetry .