ISSN:
1600-5724
Source:
Crystallography Journals Online : IUCR Backfile Archive 1948-2001
Topics:
Chemistry and Pharmacology
,
Geosciences
,
Physics
Notes:
In anthrone (10H-anthracen-9-one) crystals there may be two distinct types of molecular orientational disorder. Firstly, whole stacks of molecules along [010] may, by association with vacancies, become orientationally disordered between positions related by a twofold screw axis in the crystal. Secondly, individual molecules may become disordered between orientations related by inversion through the molecular centre of mass. Calculations with previously developed Ising-like models (with an atom-atom intermolecular potential, the data for the low-temperature unit cell and the observation of a transition temperature at 357K) reveal that at 295K both types of disorder are present. This explains previous detailed X-ray diffuse-scattering data. Parts of these data give 16 ± 1, 36 ± 9 and 25 ± 2 Å for the observed range of the order in the a, b and c directions. The calculations predict 16 ± 0, 37 ± 12 and 24 ± 6 Å.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1107/S0567739475000150
