Two new types of xenon-carbon species: the zwitterion, 1-(Xe+)C6F4-4-(BF3-), and the dication, [1,4-(Xe)2C6F4]2+.
In the 1:1 reaction of XeF(2) with 1,4-(F(2)B)(2)C(6)F(4) in 1,1,1,3,3-pentafluoropropane the insoluble zwitterion 2,3,5,6-tetrafluorophenylene-1-xenonium-4-trifluoroborate, 1-(Xe(+))C(6)F(4)-4-(BF(3)(-)), was formed as the main product (77%) along with the zwitterion, 1-(Xe(+))-cyclo-1,4-C(6)F(6)-4-(BF(3)(-)), the [BF(4)](-) salts of the dication, [1,4-(Xe)(2)C(6)F(4)](2+), and the cation, [1-Xe-cyclo-1,4-C(6)F(6)-4-H](+). The isolation of pure 1-(Xe(+))C(6)F(4)-4-(BF(3)(-)) was feasible after extraction of the byproduct with 27% aq HF. The zwitterion, 1-(Xe(+))C(6)F(4)-4-(BF(3)(-)), was characterized by multi-NMR and Raman spectroscopy and by DSC. The zwitterion, 1-(Xe(+))C(6)F(4)-4-(BF(3)(-)), reacted with halide nucleophiles (in excess) in 27% aq HF to form [4-HalC(6)F(4)BF(3)](-) (Hal = I, Br, Cl) along with [2,3,5,6-C(6)F(4)HBF(3)](-), whereas with fluoride ions [2,3,5,6-C(6)F(4)HBF(3)](-) was obtained exclusively. Reactions of XeF(2) with 1,4-(F(2)B)(2)C(6)F(4) in the molar ratio 2:1 did not allow for improving the yield of the tetrafluoroborate salt with the dication [1,4-(Xe)(2)C(6)F(4)](2+). Instead, addition of fluorine to the phenylene unit was increased with the formation of 1-(Xe(+))-cyclo-1,4-C(6)F(6)-4-(BF(3)(-)), [1-Xe-cyclo-1,4-C(6)F(6)-4-H](+), and [1,4-(Xe)(2)-cyclo-1,4-C(6)F(6)](2+). After enrichment in an anhydrous hydrogen fluoride extract, the dication, [1,4-(Xe)(2)C(6)F(4)](2+), was characterized by multi-NMR spectroscopy and by means of chemical proof (reaction with an excess of KI to 1,4-I(2)C(6)F(4)).
Inorganic Chemistry, University of Duisburg-Essen, Lotharstrasse 1, D-47048 Duisburg, Germany. h-j.frohn@uni-due.de
Hermann-Josef
HJ
Frohn
Vural
V
Bilir
Ulrich
U
Westphal