On the molecular geometry of 1,2-Di(9-anthryl)ethanes. Crystal structures of two crystalline modifications of 1,2-Bis(10-acetoxy-9-anthryl)ethane

Abstract

In order to define molecular conformations, the crystal structures of two crystalline phases of 1,2- bis(10-acetoxy-9-anthryl)ethane have been determined by single-crystal X-ray diffraction methods at 295 K. Both phases are monoclinic, P2₁/c. For the 'α'-phase, a 7.609(2), b 14.469(3), c 11.358(3) Å β, 96.39(2)º, Z 2. The final residual was 0.034 for 1341 'observed' reflections; the molecule is centrosymmetric about a crystallographic inversion centre. For the 'β'-phase, a 31.264(15), b 5.248(3), c 15.718(6) Å,β 97.84(3)º, Z 4, the final residual was 0.052 for 972 'observed' reflections. In this structure two independent, centrosymmetric molecules are found. In both α- and β-form, the molecular conformation is thus 'stretched' rather than 'eclipsed'. The packing patterns of the two modifications have been correlated with their crystal luminescence properties.