caa a22 4500 378857614 CHVBK 20180305123338.0 cr unu---uuuuu 161128e20030301xx s 000 0 eng 10.1524/zkri.218.3.221.20753 doi (NATIONALLICENCE)gruyter-10.1524/zkri.218.3.221.20753 9,10 Phenanthrenequinone, not your average structure [Elektronische Daten] [A. David Rae, A. C. Willis] 9,10-phenanthrenequinone, C14H8O2, is both polymorphic and polytypic. The β form can have different symmetries arising from different stackings of ordered layers perpendicular to cp*. These structure options are best understood using occupancy wave modulations of a 1 : 1 disordered parent structure in space group P21/c. The disorder is resolved by having ordered layers of C1̅ symmetry in a cell with a = 2ap, b = 2bp. Ordering the stacking sequence allows two orientations of a Z = 8, Cc, c = cp structure and two orientations of a Z = 16, F1̅, c = 2cp structure. It was found that for some crystals it is necessary to model the reflection data assuming uncorrelated mosaic blocks of different space group symmetry as well as orientation. Reliable geometry for both the Cc and F1̅ components were then obtained. Likewise, the α form can be described as arising from a 1 : 1 disordered parent structure in space group Pnmn where the disorder is resolved by having ordered layers of P2/c symmetry perpendicular to ap* in a cell with b = bp, c = 2cp. Ordering the stacking sequence allows two orientations of a Z = 4, P21cn structure with a = ap and two orientations of a Z = 8, B2/c structure with a = 2ap (a non standard setting of P2/c). © 2003 Oldenbourg Wissenschaftsverlag GmbH Crystallography nationallicence Inorganic chemistry nationallicence Organic chemistry nationallicence Rae A. David aut Willis A. C. aut Zeitschrift für Kristallographie - Crystalline Materials De Gruyter Oldenbourg 218/3(2003-03-01), 221-230 2194-4946 218:3<221 2003 218 zkri https://doi.org/10.1524/zkri.218.3.221.20753 text/html Onlinezugriff via DOI 1 research article jats NATIONALLICENCE 856 40 https://doi.org/10.1524/zkri.218.3.221.20753 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Rae A. David aut NATIONALLICENCE 700 1- Willis A. C. aut NATIONALLICENCE 773 0- Zeitschrift für Kristallographie - Crystalline Materials De Gruyter Oldenbourg 218/3(2003-03-01), 221-230 2194-4946 218:3<221 2003 218 zkri CC0 http://creativecommons.org/publicdomain/zero/1.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-gruyter