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The alkylation of 3‐/4‐bromo‐ and ‐iodopyridine with methyl triflate smoothly affords the corresponding N‐methylpyridinium triflate salts. An anion exchange with NaI or [PPh4]Y (Y=Cl, Br, I) yields the corresponding halide salts. Most of them could be structurally characterized and their strong halogen bonds were investigated. While the halogen atom of 4‐halogenopyridinium is susceptible to nucleophilic substitution, 3‐halogenopyridinium ions are far more stable against nucleophilic attacks. Due to the comparable interaction strength of halogen bonds and hydrogen bonds, the latter of which is widely used in chromatography, the potential of 3‐halogenopyridinium moieties for an application in chromatography is obvious and was successfully employed in affinity chromatography of different proteins. [ABSTRACT FROM AUTHOR]

The reaction of [Ga(C2F5)3(FSiMe3)] with chlorotrimethylsilane leads to the selective substitution of the α‐fluorine atoms by chlorine atoms and thus to the formation of [Ga(CCl2CF3)3(FSiMe3)]. The corresponding chlorogallate ion, [Ga(CCl2CF3)3Cl]−, could be isolated and structurally characterized as its tetraphenylphosphonium salt. The catalytic potential of [Ga(CCl2CF3)3(FSiMe3)] was demonstrated via the chlorodefluorination of Me3SiCF3, 2,2‐difluoropropane and [PPh4][Ga(C2F5)4]. [ABSTRACT FROM AUTHOR]

We synthesized new imidazolium‐based tunable aryl alkyl ionic liquids (TAAILs) with the weakly coordinating tetrakis(pentafluoroethyl)gallate anion, [Ga(C2F5)4]−. Phenyl and phenyl derivatives (2‐Me, 4‐OMe, 2,4‐F) were combined with varying alkyl chain lengths at the imidazolium core leading to TAAILs, which were investigated with regard to their viscosity, conductivity, and electrochemical window and compared to EMIM and BMIM standard cations. Remarkable low viscosities of 29 cP at 25 °C for [BMIM][Ga(C2F5)4] were achieved. However, the EMIM and BMIM gallates show electrochemical instability, releasing pentafluoroethane at a voltage of 1.5 V. The 2‐Me‐substituted gallate‐TAAILs slowly decompose over several weeks, whereas all other gallate‐TAAILs showed no decomposition at all. With electrochemical windows of up to 5.15 V and low viscosities in a range of 66–162 cP, the gallate‐TAAILs are promising candidates as electrolytes in electrochemical applications. [ABSTRACT FROM AUTHOR]

While alkyl‐substituted siloxanes are widely known, virtually nothing is known about perfluoroalkyl siloxanes and their congener species, the silanols and silanolates. We recently reported on the tris(pentafluoroethyl)silanide ion, [Si(C2F5)3]−, which features Lewis amphoteric character deriving from the pentafluoroethyl substituents and their strong electron‐withdrawing properties. Transferring this knowledge, we investigated the Lewis amphoteric behavior of the tris(pentafluoroethyl)silanolate, [Si(C2F5)3O]−. In order to examine such Lewis amphoteric behavior, we first developed a strategy for the synthesis of the corresponding silanol Si(C2F5)3OH, which readily condenses at room temperature to the hexakis(pentafluoroethyl)disiloxane, (C2F5)3SiOSi(C2F5)3. Deprotonation of Si(C2F5)3OH employing a sterically demanding phosphazene base allows the characterization of the first example of a dimeric triorganosilanolate: the dianionic hexakis(pentafluoroethyl)disilanolate, [{Si(C2F5)3O}2]2−, implies Lewis amphoteric character of the monomeric [Si(C2F5)3O]− anion. [ABSTRACT FROM AUTHOR]

The reaction of the strong monophosphazene base with the weakly acidic phenol leads to the formation of a phenol–phenolate anion with a moderately strong hydrogen bond. Application of the more powerful tetraphosphazene base (Schwesinger base) renders the isolation of the corresponding salt with a free phenolate anion possible. This compound represents the first species featuring the free phenolate anion [H5C6‐O]−. The deprotonation of phenol derivatives with tetraphosphazene bases represents a great way for the clean preparation of salts featuring free phenolate anions and in addition allows the selective syntheses of hydrogen bonded phenol‐phenolate salts. This work presents a phosphazenium phenolate salt with a redox potential of −0.72 V and its capability for the selective activation of the chemically inert greenhouse gas SF6. The performed two‐electron reduction of SF6 leads to phosphazenium pentafluorosulfanide ([SF5]−) and fluoride salts. [ABSTRACT FROM AUTHOR]

The reaction of a saline phosphazenium hydroxide hydrate with siloxanes led to a novel kind of silanol‐silanolate anions. The weakly coordinating behavior of the cation renders the formation of silanol‐silanolate hydrogen bonds possible, which otherwise suffer from detrimental silanolate–oxygen cation interactions. We investigated the influence of various weakly coordinating cations on silanol‐silanolate motifs, particularly with regard to different cation sizes. While large cations favor the formation of intramolecular hydrogen bonds resulting in cyclic structures, the less bulky tetramethyl ammonium cation encourages the formation of polyanionic silanol‐silanolate chains in the solid state. [ABSTRACT FROM AUTHOR]

Abstract: Acetonitrile is deprotonated by a combination of the strong Lewis acid (C2F5)3PF2 and triethylamine. The resulting cyanomethyl function is bound to the phosphorus moiety, affording the highly stable salt [HNEt3][P(C2F5)3F2(CH2CN)]. Salt metathesis reactions furnished the corresponding [Cu(MeCN)2]+ and [Ag(MeCN)]+ derivatives in which the CH2CN substituent of the anion [P(C2F5)3F2(CH2CN)]− coordinates to the metal. An investigation of the gas separation capability of the silver salt [Ag(MeCN)][P(C2F5)3F2(CH2CN)] shows an uptake of 1.7 equivalents of isobutene from a propane/isobutene mixture. The reaction of (C2F5)3PF2 with acetonitrile and diethylamine furnishes [P(C2F5)3F2{NHC(CH3)NEt2}]—a phosphate featuring an amidine ligand which formally results from hydroamination of acetonitrile by HNEt2. Exchange of HNEt2 with the primary amines H2NPh and H2NBu leads to comparable amidine salts that exhibit a solvent‐dependent conformational isomerism. [ABSTRACT FROM AUTHOR]

Abstract: In this contribution we report on the synthesis of bis(pentafluoroethyl)stannane, H2Sn(C2F5)2. In the reaction with donor molecules a ready elimination of hydrogen and the formation of the corresponding donor‐stabilized monomeric bis(pentafluoroethyl)stannylene, Sn(C2F5)2, becomes apparent. With dependence on the Lewis basicity and steric demand of the donor, varying coordination numbers are realized. Whereas the reaction with nitrogen bases like 4‐(dimethylamino)pyridine (DMAP) leads to the complexation of two donor molecules, [Sn(C2F5)2(dmap)2], treatment with PMe3 or [Sn(C2F5)3]− furnished the corresponding neutral or anionic monoadducts, [Sn(C2F5)2(D)] (D=PMe3, [Sn(C2F5)3]−). In contrast, the utilization of sterically demanding donors, such as iPr2O, as well as the thermal treatment of ether complexes, [Sn(C2F5)2(D)n] (D=Et2O, THF), leads to the formation of oligomeric and cyclic stannylene moieties [Sn(C2F5)2]n. The reactivity of H2Sn(C2F5)2 and the donor‐stabilized stannylenes was proven by hydrostannylation and complexation reactions with tetracarbonylnickel and bimetallic compounds. In the latter case, a donor‐dependent stannylene or distannylene insertion into the metal–metal bond was observed. [ABSTRACT FROM AUTHOR]

Abstract: The tin–tin bond cleavage of hexaorganodistannanes by nucleophiles is a long‐known reaction and widely used for stannate formation or stannyl group transfer. Herein, we detail our experiments to provide analytical evidence for the existence of the reasonably stable anionic complexes [XSn(C2F5)3{Sn(C2F5)3}]− (X=Cl, Br, I, Sn(C2F5)3) derived from hexakis(pentafluoroethyl)distannane. NMR investigations at low temperature lend further mechanistic insights. Thus, by detection of the imposing ion [Sn(C2F5)3{Sn(C2F5)3}2]−, one can surmise that the chemistry of Sn2(C2F5)6 has more in common with the isolobal iodine than with classical distannanes. [ABSTRACT FROM AUTHOR]

Abstract: Pentafluoroethyllithium, LiC2F5, has been established as an efficient and versatile reagent for the transfer of the pentafluoroethyl unit to a number of electrophiles. Here, the stability of this species up to −40 °C is of advantage, particularly in comparison to its smaller congener LiCF3. The usual production of LiC2F5, however, from gaseous HC2F5 or IC2F5 and strong bases requires specially designed apparatuses, which severely impeded its value as a laboratory reagent. In this contribution we communicate an alternative gas‐free and highly efficient protocol for the synthesis of LiC2F5 from the already commercialized stannate salt [PPh4][Sn(C2F5)5]. The [Sn(C2F5)5]− anion represents not only the first example of a structurally characterized hypervalent pentaalkylstannate but also serves as a precursor for the synthesis of the homoleptic tetrakis(pentafluoroethyl)stannane, Sn(C2F5)4. The reaction of the latter with n‐butyllithium provides an insight into the mechanism of LiC2F5 generation. [ABSTRACT FROM AUTHOR]