Polyfluoroorganotrifluoroborates and -difluoroboranes: interesting materials in fluoroorgano and fluoroorgano-element chemistry

From hypervalent xenon difluoride and aryliodine(III) difluorides to onium salts: Scope and limitation of acidic fluoroorganic reagents in the synthesis of fluoroorgano xenon(II) and iodine(III) onium salts

“…The high acidity of (4-C 5 F 4 N)BF 2 which played an important role in the distinct reactivity of (4-C 5 F 4 N)BF 2 and C 6 F 5 BF 2 towards XeF 2 (see Section 2.1) is supported by the pF À values in the gas phase. The higher acidity of (4-C 5 F 4 N)BF 2 in comparison to that of C 6 F 5 BF 2 is also in agreement with the experimental finding that for the abstraction of fluoride from K[(4-C 5 F 4 N)BF 3 ] the strong Lewis acid AsF 5 is needed [22] whereas less strong BF 3 is sufficient in case of K[C 6 F 5 BF 3 ] [28]. Based on our present knowledge about the interaction of the EF 2 triad with Lewis acids RAF nÀ1 we can principally discuss three simplified cases: (a) abstraction of fluoride and formation of [EF][RAF n ] (contact ion pairs or solvent separated ions), (b) adduct formation, mainly stabilized by insolubility, and (c) weak interaction under polarization of one E-F bond, followed by the migration of the nucleophilic group R to the electrophilic center E.…”

“…Now we append to the former investigation [22] the following two reactions with less than 1 equiv. of (4-C 5 F 4 N)BF 2 (Eqs.…”

Polyvalent perfluoroorgano- and selected polyfluoroorgano-halogen(III and V) compounds

“…A straightforward preparative approach to per-and polyfluoroorganodifluoroboranes R F BF 2 (R F = C 6 F n H 5Àn , R 00 CF = CF, CF 2 = CR 00 , R 00 CBBC) in weakly coordinating solvents (CH 2 Cl 2 , 1,1,1,3,3-pentafluoropropane (PFP), 1,1,1,3,3-pentafluorobutane (PFB)) was developed by Frohn and Bardin in the last decade [63,64] and allowed the syntheses of a number of symmetric and asymmetric bis(per-and polyfluoroaryl)iodonium (Eqs. (39a) and (39b)) [65,21,66], perfluoroalkenyl(aryl)iodonium (Eq. (39c)) [21,66], perfluoroalkynyl(aryl)iodonium, perfluoroalkynyl(perfluoroalkenyl)-iodonium, perfluoroalkynyl(polyfluoroalkyl)iodonium (Eq.…”

“…(39a) and (39b)) [65,21,66], perfluoroalkenyl(aryl)iodonium (Eq. (39c)) [21,66], perfluoroalkynyl(aryl)iodonium, perfluoroalkynyl(perfluoroalkenyl)-iodonium, perfluoroalkynyl(polyfluoroalkyl)iodonium (Eq. (39d)) [18], and perfluoroalkyl(perfluorophenyl) iodonium [5,67] tetrafluoroborates (Eq.…”

Organoxenonium Salts: Synthesis by "Xenodeborylation", Reactivities, and NMR Spectroscopic Properties

“…Alkynyldifluoroboranes, XCs=CBF 2 , like aryldifluoroboranes do not possess a substituent in addition to the BF 2 group at C-l and their fluoride affinities of prototypical species vary from 68.9 (X = CH 3 ) to 89.0 (X = CF 3 ), while the fluoride affinity of C 6 F 5 BF 2 is 85.1 kcal mol" 1 (21). The greater Lewis acidity of XCs=CBF 2 results in a remarkable enhancement in the competing reaction of XeF 2 with CH 2 C1 2 solvent.…”