[Show abstract][Hide abstract] ABSTRACT: The iodonium pseudohalide compounds, [(C6F5)(2)I][X] (X = SCN and CN) were synthesized by means of fluoride substitution in [(C6F5)(2)I][F] with the Lewis acidic reagents (CH3)(3)Si-NCS and (CH3)(3)Si-CN. The isolated iodonium pseudohalides are intrinsically unstable solids. Decomposition resulted in equimolar amounts of C6F5I and C6F5SCN or C6F5I and C6F5CN, respectively. In case of [(C6F5)(2)I][SCN] single crystals could be grown from CH2Cl2. The crystal structure revealed a dimer with an eight membered ring formed by two ambident anions bridging the iodine atoms of two cations by N and S coordination. The favored dimerization of [(C6F5)(2)I][SCN] and [(C6F5)(2)I][CN] in the gas phase is supported by ab initio computations. (C) 2014 Published by Elsevier B.V.
[Show abstract][Hide abstract] ABSTRACT: Potassium perfluoroalkenyl(fluoro)borates, K[RFBF3], (RF = CF2C(CF3), cis-CF3CFCF, and cis-C6F13CFCF) decomposed at 208–225 °C (Tmax, dTG). The K[RFBF3] salts (RF = C3F7, C6F13, trans-CF3CFCF, and trans-C4F9CFCF) decomposed at 273–312 °C (Tmax, dTG). Both groups of salts formed volatile polyfluoroorganics and K[BF4] as solid residue. The preparative thermolysis of selected prototypical salts K[RFBF3] showed that the polyfluoroorganics consisted of a mixture of internal perfluorohexenes, C6F12, and 1-H-tridecafluorohexane, C6F13H, in case of K[C6F13BF3], and of perfluorooctynes, C8F14, and cis-C6F13CFCFH in case of K[cis-C6F13CFCFBF3]. The salts K[(C6F5)2BF2] and K[RFBF3] (RF = CF3CC, CF3CFCFCC, C6F5CC, C6F5, 2,3,5,6-C5NF4) decomposed in the temperature range 249–337 °C (Tmax, dTG) and mainly resulted in non-volatile polyfluoroorganics besides K[BF4]. The reaction path of the thermolysis of perfluoroalkyl-, perfluoroalkenyl-, and perfluorophenyl(fluoro)borates is discussed and compared with that of perfluorocarboxylates.
[Show abstract][Hide abstract] ABSTRACT: Heating of the neat salts [4-FC6H4N2][RFBF3] (RF = C6F5, C6F13, trans-C4F9CFCF, cis-C6F13CFCF, CF3CC) or in solid mixtures with NaF gives the principal product 1,4-C6F2H4 besides RFBF2 or Na[RFBF3], respectively. Thermolysis of [4-FC6H4N2][(C6F13)2BF2] in NaF results in 1,4-C6F2H4, Na[BF4], Na[(C6F13)2BF2], and a new type of product, the isomer Na[C6F13CF(BF3)C5F11].
[Show abstract][Hide abstract] ABSTRACT: The arylxenonium salt [C6F5Xe][BF4] reacts with different sources of nucleophiles, Y (naked fluoride, [N(CH3)4]F, the silanes, (CH3)3SiCl and (C2H5)3SiH, and the cadmiumorganyl, Cd(C6F5)2), in coordinating solvents (C2H5CN, CH3CN, CD3CN). While the products C6F5XeF, C6F5XeCl, and (C6F5)2Xe are well defined molecules, in reactions with (C2H5)3SiH only decomposition products presumably derived from and are found. Molecular parameters and intermolecular contacts in the single crystal X-ray structure of C6F5XeF are discussed.
[Show abstract][Hide abstract] ABSTRACT: First examples of alk-1-yn-1-yliodine(V) molecules, CF3CCIF4 and C6F13CCIF4, were prepared by fluorination of the corresponding 1-iodoperfluoroalk-1-ynes with XeF2 in 1,1,1,3,3-pentafluorobutane (PFB) in the presence of BF3. The reaction of 1-iodo-2-(4-heptafluorotolyl)ethyne, 4-CF3C6F4CCI, with XeF2 (1.5 equiv) and BF3 resulted in a mixture of 4-CF3C6F4CCIF2 (main product), 4-CF3C6F4CCIF4, and trans-(4-CF3C6F4)CFCFI, whereas under the action of 3 equiv of XeF2/BF3 a complex mixture of polyfluoroorganics and IF5 resulted. Non-fluorinated C4H9CCI reacted with XeF2/BF3 preferentially under fluorine addition across the triple bond and gave mainly C4H9CF2CF2I. The differing reactivity of CnF2n+1CCI and C4H9CCI is in accordance with the experimentally proved different reactivity of the triple bond in C6F13CCH and C4H9CCH toward XeF2/BF3 in PFB. Compound C6F13CCH was inert whereas C4H9CCH was converted into C4H9CF2CF2H (main product) under the same conditions.
[Show abstract][Hide abstract] ABSTRACT: 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)).
[Show abstract][Hide abstract] ABSTRACT: Three prototypical fluoroaryliodonium salts with the [N(CF3)2]− anion were obtained by metathesis in the corresponding tetrafluoroborate salts [Ar(Ar′)I][BF4] (Ar/Ar′ = C6H5/4-FC6H4, 3-FC6H4/4-FC6H4, C6F5/C6F5) with in situ generated Rb[N(CF3)2]. The kinetic lability of the [N(CF3)2]− anion (potential fluoride donor like [OCF3]−) in combination with the gradual change in fluoride affinity of the three [Ar(Ar′)I]+ fluoroaryliodonium cations allowed to distinguish the fluoride acceptor property of the three [Ar(Ar′)I]+ fluoroaryliodonium cations. Coordinating solvents or ligands suppressed the fluoride transfer from the [N(CF3)2]− anion to the fluoroaryliodonium cation.
[Show abstract][Hide abstract] ABSTRACT: Xenon difluoride reacted with alkynylborate salts, K[RFCCBF3], in anhydrous HF (aHF) to give alkynylxenonium salts, [RFCCXe][BF4] (RF = CF3, C3F7, (CF3)2CF), in 50–55% yield. Both [FXe][SbF6] and K[C3F7CCBF3] formed the [C3F7CCXe]+ salt in aHF. In the reaction of XeF2 with the alkenylborate salt, K[CF2C(CF3)BF3], the competitive hydrodeboration reaction (formation of CF2C(CF3)H in 85% yield) exceeded the xenodeboration reaction (formation of the xenonium salt [CF2C(CF3)Xe][BF4] in 15% yield only). K[4-BF3C5F4N] did not react with XeF2 in aHF, but underwent fluorine addition in the presence of AsF5.
[Show abstract][Hide abstract] ABSTRACT: The asymmetric unit of the title compound, C(12)H(18)F(4)Si(2), contains two independent mol-ecules, both lying on inversion centers. The C(arene)-Si distances are significantly longer than in the analogous non-fluorinated compound. The packing of the mol-ecules results in a herringbone motif in the ac plane.
[Show abstract][Hide abstract] ABSTRACT: The relative rate of the electrophilic hydrodeboration of K[R′BF3] with HF (27–100%) diminishes in the series R′=C4H9CC>C4F9CFCFCC>CF2C(CF3)>C3F7CC∼(CF3)2CFCC>CF3CC. When R′=CF3CC the new salt K[CF3CH2–CF2BF3] was obtained by addition of HF besides CF3CCH and K[BF4]. Small amounts of water caused the formation of K[CF3CH2–C(O)BF3] as a by-product. The electrophilic halofluorination of perfluoroalkenyltrifluoroborate salts with NCS or NBS in aHF (anhydrous HF) led to K[RFCFHal–CF2BF3] (from K[RFCFCFBF3]) and K[RFCHal2–CF2BF3] (from K[RFCHalCFBF3] and K[RFCCBF3]) (Hal=Cl, Br). Treatment of K[RFCFCFBF3] and K[RFCCBF3] with 5% F2/N2 in MeCN gave the corresponding salts K[RFCF2–CF2BF3] in 16–25% isolated yield. Reactions of K[trans-C4F9CFCFBF3] with Cl2 in MeOH resulted in K[C4F9CFCl–C(O)BF3] (major product). The latter was also obtained in reactions of K[trans-C4F9CFCFBF3] with Cl2 in MeCN or sulfolane after sequential methanolysis of the primarily formed products. In contrast, the salts K[RCFCFBF3] (R=CnF2n+1, trans-C4H9) and K[CF3CCBF3] underwent bromodeboration to RCFCFBr and CF3CCBr, respectively, when they were reacted with bromine in the polar solvents MeOH, MeCN, or sulfolane.
[Show abstract][Hide abstract] ABSTRACT: Perfluoroalkynylxenonium salts, [RXe][BF(4)] (R = CF(3)C≡C, (CF(3))(2)CFC≡C), reacted with organyl iodides, R'I (R' = 3-FC(6)H(4), C(6)F(5), CF(2)═CF, CF(3)CH(2); no reaction with R' = CF(3)CF(2)CF(2)) in anhydrous HF to yield the corresponding asymmetric polyfluorinated iodonium salts, [RR'I][Y]. The action of the arylxenonium salt, [C(6)F(5)Xe][BF(4)], and the cycloalkenylxenonium salt, [cyclo-1,4-C(6)F(7)Xe][AsF(6)], on 4-FC(6)H(4)I gave [C(6)F(5)(4-FC(6)H(4))I][BF(4)] and [cyclo-1,4-C(6)F(7)(4-FC(6)H(4))I][AsF(6)], respectively, besides the symmetric iodonium salt, [(4-FC(6)H(4))(2)I][Y]. But the aryl-, as well as the cycloalkenylxenonium salt, did not react with C(6)F(5)I, CF(2)═CFI, and CF(3)CH(2)I.
[Show abstract][Hide abstract] ABSTRACT: Two routes to RFIF6 compounds were investigated: (a) the substitution of F by RF in IF7 and (b) the fluorine addition to iodine in RFIF4 precursors. For route (a) the reagents C6F5SiMe3, C6F5SiF3, [NMe4][C6F5SiF4], C6F5BF2, and 1,4-C6F4(BF2)2 were tested. C6F5IF4 and CF3CH2IF4 were used in route (b) and treated with the fluoro-oxidizers IF7, [O2][SbF6]/KF, and K2[NiF6]/KF. The observed sidestep reactions in case of routes (a) and (b) are discussed. Interaction of C6F5SiX3 (X=Me, F), C6F5BF2, 1,4-C6F4(BF2)2 with IF7 gave exclusively the corresponding ring fluorination products, perfluorinated cyclohexadiene and cyclohexene derivatives, whereas [NMe4][C6F5SiF4] and IF7 formed mixtures of C6FnIF4 and C6FnH compounds (n=7 and 9). CF3CH2IF4 was not reactive towards the fluoro-oxidizer IF7, whereas C6F5IF4 formed C6FnIF4 compounds (n=7 and 9). C6F5IF4 and CF3CH2IF4 were inert towards [O2][SbF6] in anhydrous HF. CF3CH2IF4 underwent C–H fluorination and C–I bond cleavage when treated with K2[NiF6]/KF in HF. The fluorine addition property of IF7 was independently demonstrated in case of perfluorohexenes. C4F9CFCF2 and IF7 underwent oxidative fluorine addition at −30°C, and the isomers (CF3)2CFCFCFCF3 (cis and trans) formed very slowly perfluoroisohexanes even at 25°C. The compatibility of IF7 and selected organic solvents was investigated. The polyfluoroalkanes CF3CH2CHF2 (PFP), CF3CH2CF2CH3 (PFB), and C4F9Br are inert towards iodine heptafluoride at 25°C while CF3CH2Br was slowly converted to CF3CH2F. Especially PFP and PFB are new suitable organic solvents for IF7.
[Show abstract][Hide abstract] ABSTRACT: A series of previously unknown asymmetrical fluorinated bis(aryl)bromonium, alkenyl(aryl)bromonium, and alkynyl(aryl)bromonium salts was prepared by reactions of C6F5BrF2 or 4-CF3C6H4BrF2 with aryl group transfer reagents Ar′SiF3 (Ar′=C6F5, 4-FC6H4, C6H5) or perfluoroorganyl group transfer reagents RF′BF2 (RF=C6F5, trans-CF3CFCF, C3F7C≡C) preferentially in weakly coordinating solvents (CCl3F, CCl2FCClF2, CH2Cl2, CF3CH2CHF2 (PFP), CF3CH2CF2CH3 (PFB)). The presence of the base MeCN and the influence of the adducts RF′BF2·NCMe (RF=C6F5, CF3C≡C) on reactions aside to bromonium salt formation are discussed. Reactions of C6F5BrF2 with AlkF′BF2 in PFP gave mainly C6F5Br and AlkF′F (AlkF′=C6F13, C6F13CH2CH2), presumably, deriving from the unstable salts [C6F5(AlkF′)Br]Y (Y=[AlkF′BF3]−). Prototypical reactivities of selected bromonium salts were investigated with the nucleophile I–and the electrophile H+. [4-CF3C6H4(C6F5)Br][BF4] showed the conversion into 4-CF3C6H4Br and C6F5I when reacted with [Bu4N]I in MeCN. Perfluoroalkynylbromonium salts [CnF2n+1C≡C(RF)Br][BF4] slowly added HF when dissolved in aHF and formed [Z–CnF2n+1CFCH(RF)Br][BF4].
[Show abstract][Hide abstract] ABSTRACT: Bromonium salts [(RF)2Br]Y with perfluorinated groups RFC6F5, CF3CFCF, C2F5CFCF, and CF3C≡C were isolated from reactions of BrF3 with RFBF2 in weakly coordinating solvents (wcs) like CF3CH2CHF2 (PFP) or CF3CH2CF2CH3 (PFB) in 30–90% yields. C6F5BF2 formed independent of the stoichiometry only [(C6F5)2Br][BF4]. 1:2 reactions of BrF3 and silanes C6F5SiY3 (Y=F, Me) ended with different products – C6F5BrF2 or [(C6F5)2Br][SiF5] – as pure individuals, depending on Y and on the reaction temperature (Y=F). With C6F5SiF3 at ≥−30°C [(C6F5)2Br][SiF5] resulted in 92% yield whereas the reaction with less Lewis acidic C6F5SiMe3 only led to C6F5BrF2 (58%). The interaction of K[C6F5BF3] with BrF3 or [BrF2][SbF6] in anhydrous HF gave [(C6F5)2Br][SbF6]. Attempts to obtain a bis(perfluoroalkyl)bromonium salt by reactions of C6F13BF2 with BrF3 or of K[C6F13BF3] with [BrF2][SbF6] failed. The 3:2 reactions of BrF3 with (C6F5)3B in CH2Cl2 gave [(C6F5)2Br][(C6F5)nBF4−n] salts (n=0–3). The mixture of anions could be converted to pure [BF4]− salts by treatment with BF3·base.
[Show abstract][Hide abstract] ABSTRACT: A promising approach to the unknown type of [Ar′(Ar)IF2]X salts is offered. x-FC6H4IF4 (x=2, 3, 4) reacts with C6F5BF2 in CH2Cl2 and forms [x-FC6H4(C6F5)IF2][BF4] salts in good yields. For [4-FC6H4(C6F5)IF2][BF4] the fluoro-oxidizer property is shown in reactions with weakly reducing agents like E(C6F5)3 (E=P, As, Sb, Bi) and ArI (Ar=4-FC6H4, C6F5). The fluorine/aryl substitution method is also applied to the synthesis of [(4-FC6H4)2IF2][BF4], an example with two identical aryl groups in the difluoroiodonium(V) moiety.
[Show abstract][Hide abstract] ABSTRACT: The adducts of aryliodinedifluorides ArfIF2, (Arf = C6F5; x-FC6H4, x = 2, 3, 4) and aryliodinedicyanide 4-FC6H4I(CN)2 with N-bases (phenanthroline, 2,2′-bipyridine, and quinoline) were isolated and characterized by their single crystal structure, Raman spectra, and their multi nuclear magnetic resonance spectra in solution. Their properties and their thermal decomposition are discussed with respect to the non-coordinated analogues.
[Show abstract][Hide abstract] ABSTRACT: Bis(pentafluorophenylxenonium) tetrafluoroterephthalate (1) was obtained by metathesis reactions of pentafluorophenylxenonium and tetrafluoroterephthalate salts. The availability of suitable solvents for the metatheses hampered the optimization of the reaction. The new xenon–carbon compound with two polar Xe–O bonds was characterized by NMR spectroscopy in solution and by Raman spectroscopy in the solid state. From (CF3)2CHOH/MeCN solutions single crystals were obtained with four alcohol molecules attached to 1 by hydrogen bridges. The thermal properties of the intrinsically unstable title compound are reported.
[Show abstract][Hide abstract] ABSTRACT: The relative fluoride donor ability: C6F5BrF2 > C6F5IF2 > C6F5IF4 was outlined from reactions with Lewis acids of graduated strength in different solvents. Fluoride abstraction from C6F5HalF2 with BF3·NCCH3 in acetonitrile (donor solvent) led to [C6F5HalF·(NCCH3)n][BF4]. The attempted generation of [C6F5BrF]+ from C6F5BrF2 and anhydrous HF or BF3 in weakly coordinating SO2ClF gave C6F5Br besides bromoperfluorocycloalkenes C6BrF7 and 1-BrC6F9. In reactions of C6F5IF2 with SbF5 in SO2ClF the primary observed intermediate (19F NMR, below 0 °C) was the 4-iodo-1,1,2,3,5,6-hexafluorobenzenium cation, which converted into C6F5I and 1-IC6F9 at 20 °C. The reaction of C6F5IF4 with SbF5 in SO2ClF below −20 °C gave the cation [C6F5IF3]+ which decomposed at 20 °C to C6F5I, 1-iodoperfluorocyclohexene, and iodoperfluorocyclohexane. Principally, the related perfluoroalkyl compound C6F13IF4 showed a different type of products in the fast reaction with AsF5 in CCl3F (−60 °C) which resulted in C6F14. Intermediate and final products of C6F5HalFn−1 (n = 3, 5) with Lewis acids were characterized by NMR in solution. Stable solid products were isolated and analytically characterized.
[Show abstract][Hide abstract] ABSTRACT: The first representatives of the previously unknown perfluoroalkyl(perfluoroaryl)iodonium salts [CnF2n + 1(ArF)I]Y were prepared by reaction of perfluorinated alkyliodine difluorides CnF2n + 1IF2 with aryldifluoroborane C6F5BF2 and on the complementary route from perfluorinated aryliodine difluoride C6F5IF2 and alkyldifluoroborane C6F13BF2.