title: Two polymorphic forms of 2,5-bis(4-methoxycarbonylphenyl)-1,3,4-oxadiazole.
abstract: The title compound [systematic name: dimethyl 4,4'-(1,3,4-oxadiazole-2,5-diyl)diphenylenedicarboxylate], C(18)H(14)N(2)O(5), crystallizes under similar conditions in two different orthorhombic crystalline forms. In both forms, the molecule consists of two equivalent parts. In form 1, these parts are related by a twofold axis of space group Pbcn, and in form 2, by a mirror plane of space group Cmc2(1). The O atom of the oxadiazole ring occupies a special position on the twofold axis and on the mirror plane in forms 1 and 2, respectively.
authors: Bundesanstalt für Materialforschung und -prüfung, Richard-Willstätter-Strasse 11, D-12489 Berlin, Germany. guenter.reck@bam.de
authors: Günter
authors: G
authors: Reck
authors: Ingo
authors: I
authors: Orgzall
authors: Burkhard
authors: B
authors: Schulz
authors: Birgit
authors: B
authors: Dietzel