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Fluorinated organodifluoroboranes R f BF 2 are in general suitable reagents to transform XeF 2 and RIF 2 into the corresponding onium tetrafluoroborate salts [R f Xe][BF 4 ] and [R(R f )I][BF 4 ], respectively. (4-C 5 F 4 N)BF 2 and trans -CF 3 CF CFBF 2 which represent boranes of high acidity form no Xe–C onium salts in reactions with XeF 2 but give the desired iodonium salts with RIF 2 (R = C 6 F 5 , o -, m -, p -C 6 FH 4 ). The reaction of (4-C 5 F 4 N)BF 2 with XeF 2 ends with a XeF 2 –borane adduct. C 6 F 5 Xe(4-C 5 F 4 N), the first Xe-(4-C 5 F 4 N) compound, was obtained when C 6 F 5 XeF was reacted with Cd(4-C 5 F 4 N) 2 . We describe the synthesis of (4-C 5 F 4 N)IF 2 and reactions of (4-C 5 F 4 N)IF 2 and C 6 F 5 IF 2 with (4-C 5 F 4 N)BF 2 . Analogous to [(4-C 5 F 4 N) 2 I][BF 4 ] and [C 6 F 5 (4-C 5 F 4 N)I][BF 4 ] aryl(perfluoroalkenyl)iodonium salts [R(R′)I][BF 4 ] were obtained from RIF 2 (R = C 6 F 5 , o -, m -, p -C 6 FH 4 ) and R′BF 2 (R′ = trans -CF 3 CF CF, CF 2 CF). The gas phase fluoride affinities pF − of selected fluoroorganodifluoroboranes R f BF 2 and their hydrocarbon analogs are calculated (B3LYP/6-31+G * ) and discussed with respect to their potential to introduce R f -groups into hypervalent EF 2 bonds. Four aspects which influence the transformation of hypervalent EF 2 bonds (E = Xe, R′I) under the action of Lewis acidic reagents RAF n −1 (A = B, P; n = 3, 5) into the corresponding [RE][AF n +1 ] salts are presented and the important role of the acidity is emphasized. Fluoride affinities may help to plan the introduction of organo groups into EF 2 moieties and to expand the types of acidic reagents. Thus C 6 H 5 PF 4 with a pF − value comparable to that of R f BF 2 compounds is able to introduce the C 6 H 5 group into RIF 2 (R = C 6 F 5 , p -C 6 FH 4 ). |
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