Crystal structure of two isostructural tetramethyldioxapyrene salts

Michael Hjorth, Niels Thorup, Jørn B. Christensen and Klaus Bechgaard


The crystal structures of two organic conductors di(3,5,8,10-tetramethyl-1,6-dioxapyrenium) tetrafluoroborate, (C18H16O2)+2 BF4, and di(3,5,8,10-tetramethyl-1,6-dioxapyrenium) hexafluorophosphate, (C18H16O2)+2 PF6, have been studied with single crystal X-ray diffraction methods. The two salts are isostructural and crystallize in the space group Pmna, Z = 2, with the unit cell parameters a = 6.772(1), b = 9.762(1) and c = 21.825(2) Å for the BF4 salt and a = 6.792(1), b = 9.769(1) and c = 22.096(3) Å for the PF[unk] salt. The models were refined to R-values of 0.082 (BF[unk]) and 0.069 (PF[unk]) using 860 and 979 reflections, respectively, with I> 2σ(I). The tetramethyldioxapyrene molecules lie on mirror planes stacked along the a-axis with an interplanar distance of exactly a/2 (3.386 and 3.396 Å for the BF[unk] and PF[unk] structure, respectively). The BF[unk] anion exhibits considerable disorder whereas the PF[unk] anion is ordered, which is reflected in the higher R-value for the BF[unk] structure. Both salts are semiconductors.

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Zeitschrift für Kristallographie – Crystalline Materials offers a place for researchers to present results of their crystallographic studies. The journal includes theoretical as well as experimental research. It publishes Original Papers, Letters and Review Articles in manifold areas of crystallography.