Crystal structure of two isostructural tetramethyldioxapyrene salts

Abstract

Abstract The crystal structures of two organic conductors di(3,5,8,10-tetramethyl-1,6-dioxapyrenium) tetrafluoroborate, (C18H16O2)+ 2 BF− 4, and di(3,5,8,10-tetramethyl-1,6-dioxapyrenium) hexafluorophosphate, (C18H16O2)+ 2 PF− 6, 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 BF− 4 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.