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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]

Although the adduct of aluminum trichloride with thionyl chloride has been reported, no thionyl chloride adduct of a main group element Lewis acid or organometallic compound has been structurally characterized. In this communication we present the synthesis and reactivity of the structurally ascertained adduct of thionyl chloride with tris(pentafluoroethyl)gallane as a representative of a main group element Lewis acid. Gallium and indium compounds with electron withdrawing groups, e.g. the pentafluoroethyl ligand, display versatile properties. While gallates and indates, [MR4]−, behave as weakly coordinating anions, neutral gallanes and indanes, MR3, are strong Lewis acids. Salts with the tetrakis(pentafluoroethyl)gallate and ‐indate, [M(C2F5)4]− (M=Ga, In), have recently been studied in detail. In contrast to this, work on the syntheses of the free Lewis superacids M(C2F5)3 (M=Ga, In) is scarce and underdeveloped. The hydrates [M(C2F5)3(OH2)2] proved to be suitable starting materials, particularly due to their thermal stability. Herein we report on synthesis and characterization of reactive adducts, [M(C2F5)3D], with the weak donor molecules (D) SOCl2 and Me3SiF. The effective Lewis acidities of Ga(C2F5)3 and In(C2F5)3 were experimentally determined by the (modified) Gutmann‐Beckett method and their catalytic potential is showcased. [ABSTRACT FROM AUTHOR]

Although the adduct of aluminum trichloride with thionyl chloride has been reported, no thionyl chloride adduct of a main group element Lewis acid or organometallic compound has been structurally characterized. In this communication we present the synthesis and reactivity of the structurally ascertained adduct of thionyl chloride with tris(pentafluoroethyl)gallane as a representative of a main group element Lewis acid. Gallium and indium compounds with electron withdrawing groups, e.g. the pentafluoroethyl ligand, display versatile properties. While gallates and indates, [MR4]−, behave as weakly coordinating anions, neutral gallanes and indanes, MR3, are strong Lewis acids. Salts with the tetrakis(pentafluoroethyl)gallate and ‐indate, [M(C2F5)4]− (M=Ga, In), have recently been studied in detail. In contrast to this, work on the syntheses of the free Lewis superacids M(C2F5)3 (M=Ga, In) is scarce and underdeveloped. The hydrates [M(C2F5)3(OH2)2] proved to be suitable starting materials, particularly due to their thermal stability. Herein we report on synthesis and characterization of reactive adducts, [M(C2F5)3D], with the weak donor molecules (D) SOCl2 and Me3SiF. The effective Lewis acidities of Ga(C2F5)3 and In(C2F5)3 were experimentally determined by the (modified) Gutmann‐Beckett method and their catalytic potential is showcased. [ABSTRACT FROM AUTHOR]

Bidentate and tetradentate chalcogen bonding host systems with SeCF3 functions as σ-hole donors in close proximity at the alkyne functions of 1,8-diethynylanthracene and its syn-dimer were prepared in quantitative yield by tin-selenium exchange reactions of the corresponding trimethylstannyl precursors with ClSeCF3. The bidentate system shows chalcogen bonding interactions with THF, but does not bind halide ions. The tetradentate system cooperatively chelates chloride, bromide and iodide ions with its four C≡C–SeCF3 units by rotating the four σ-holes towards the halide ion. The structures of these halide ion adducts were determined by X-ray diffraction. The hydrobromide and -iodide salts of the ethyl derivative of Schwesinger's phosphazene superbase served as halide salts with very weakly coordinating cations. [ABSTRACT FROM AUTHOR]

Poly(vinyl alcohol) (PVA) has ice binding and ice nucleating properties. Here, we explore the dependence of the molecular size of PVA on its ice nucleation activity. For this purpose, we studied ice nucleation in aqueous solutions of PVA samples with molar masses ranging from 370 to 145 000 g mol−1, with a particular focus on oligomer samples with low molar mass. The experiments employed a novel microfluidic setup that is a follow-up on the previous WeIzmann Supercooled Droplets Observation on a Microarray (WISDOM) design by Reicher et al. The modified setup introduced and characterized here, termed nanoliter Bielefeld Ice Nucleation ARraY (nanoBINARY), uses droplet microfluidics with droplets (96 ± 4) µm in diameter and a fluorinated continuous oil phase and surfactant. A comparison of homogeneous and heterogeneous ice nucleation data obtained with nanoBINARY to those obtained with WISDOM shows very good agreement, underpinning its ability to study low-temperature ice nucleators as well as homogeneous ice nucleation due to the low background of impurities. The experiments on aqueous PVA solutions revealed that the ice nucleation activity of shorter PVA chains strongly decreases with a decrease in molar mass. While the cumulative number of ice nucleating sites per mass nm of polymers with different molar masses is the same, it becomes smaller for oligomers and completely vanishes for dimer and monomer representatives such as 1,3-butanediol, propan-2-ol, and ethanol, most likely because these molecules become too small to effectively stabilize the critical ice embryo. Overall, our results are consistent with PVA polymers and oligomers acting as heterogeneous ice nucleators. [ABSTRACT FROM AUTHOR]

Tris(pentafluoroethyl)indane dihydrate, [In(C2F5)3(OH2)2], and the gallium analog, [Ga(C2F5)3(OH2)2], serve as transfer reagents for the In(C2F5)3 and Ga(C2F5)3 units, as illustrated by the preparation of salts of (pseudo)halogenotris(pentafluoroethyl)indate and ‐gallate anions, [M(C2F5)3)X]− (M=Ga, In; X=F, Cl, Br, I, CN, SCN). Due to the water tolerance and water solubility of [In(C2F5)3(OH2)2] and [Ga(C2F5)3(OH2)2], reactions can be performed in the presence of water or even in an aqueous medium. [ABSTRACT FROM AUTHOR]

Lewis superacids (LSA) are defined by a fluoride ion affinity (FIA) that exceeds that of SbF5, and are thus characterized as hard according to the HSAB concept. Soft superacidity was defined for compounds exceeding the hydride ion affinity (HIA) of B(C6F5)3. Herein we report on the synthesis of a Lewis acid being superacidic only on the soft regime: tris(pentafluoroethyl)indane, In(C2F5)3. It is accessible in the form of its dihydrate [In(C2F5)3(OH2)2]. An improved synthesis for the gallium analogue [Ga(C2F5)3(OH2)2] is also reported. Tris(pentafluoroethyl)indane dihydrate, [In(C2F5)3(OH2)2], was fully characterized by IR and NMR spectroscopy, as well as by single crystal X‐ray diffraction. Due to their stability and convenient accessibility, the hydrates are ideal starting compounds for the chemistry of tris(pentafluoroethyl)gallium and ‐indium compounds, for example hydroxogallates and ‐indates. An attempt to determine its gas‐phase structure and that of the gallium analogue by electron diffraction demonstrates that they lose water ligands upon evaporation. The energetics of these processes were predicted by quantum‐chemical calculations as was the nature of bonding in the free Lewis acids and their mono‐ and dihydrates. Furthermore, the synthesis and structural diversity of hydroxido tris(pentafluoroethyl) gallates and one indate are presented. [ABSTRACT FROM AUTHOR]

The introduction of a number of unsaturated fluorinated and chlorinated substituents onto gallium and indium was investigated. Gallate, [GaR4]−, and indate, [InR4]−, anions with trifluorovinyl (CF=CF2), 1‐chloro‐2,2‐difluorovinyl (CCl=CF2), (E)‐pentafluoropropen‐1‐yl (E‐CF=CFCF3), 3,3,3‐trifluoropropynyl (C≡C−CF3) and dichloromethyl (CHCl2) substituents were synthesized and isolated as the respective tetraphenylphosphonium salts. The respective gallate and indate salts were characterized by various methods, including NMR spectroscopy, mass spectrometry and X‐ray diffraction analysis. The generation of the respective organyllithium reagents, required for the syntheses of the gallate and indates, was performed starting from commercially available materials. This series of novel gallate and indate salts extends the chemistry of electron withdrawing groups to gallium and indium compounds. [ABSTRACT FROM AUTHOR]

Phosphoranides comprising three phosphorus carbon bonds are scarcely represented in the literature. We now utilized tris(pentafluoroethyl)phosphane, P(C2F5)3, and cyanobis(pentafluoroethyl)phosphane, P(C2F5)2(CN), featuring electron withdrawing pentafluoroethyl groups, to synthesize such compounds. Metal fluorides MF (M=Ag, Cs) add to P(C2F5)3 yielding respective M[P(C2F5)3F] salts. Those M[P(C2F5)3F] subsequently suffer a loss of C2F4, furnishing M[P(C2F5)2F2]. The cesium salt decomposes instantaneously when warmed to rt, whereas the silver salt decomposes slowly over several days at rt. Treatment of Ag[P(C2F5)3F] with 2,2'‐bipyridine facilitated the isolation and structural characterization of [Ag(bipy){P(C2F5)3F}]. With P(C2F5)2(CN), AgF reacts under substitution of the cyano group yielding P(C2F5)2F, rather than phosphoranide formation. However, [K(18‐crown‐6)]F adds to P(C2F5)2(CN) furnishing [K(18‐crown‐6)][P(C2F5)2(CN)F]. Its structural characterization was successful, despite its tendency to undergo an exchange of substituents, yielding [K(18‐crown‐6)][P(C2F5)2F2] and presumably [K(18‐crown‐6)][P(C2F5)2(CN)2]. The latter forms an equilibrium with [K(18‐crown‐6)]CN and P(C2F5)2(CN) which lies well on side of the phosphane and cyanide salt. [ABSTRACT FROM AUTHOR]

In the rising field of organoindium chemistry little is known about the perfluoroorganyl‐substituted indium compounds. The increasing use of indium reagents is explained by their high stability and tolerance towards water and functional groups. Here we report on the synthesis of the novel tetrakis(pentafluoroethyl)indate, [In(C2F5)4]−, and its characterization in salts with the cations [Li(thf)3]+, Cs+, [PPh4]+ and [H14O6]2+ (thf=tetrahydrofuran). To the best of our knowledge, these salts constitute the first perfluoroalkylindates and, in general, the first isolated perfluoroalkylindium compounds which are fully characterized by NMR spectroscopy, mass spectrometry, elemental analysis and X‐ray diffraction analysis. [ABSTRACT FROM AUTHOR]

Novel acrylate polymers functionalized with tetrafluorophenyl phosphonic acid groups were prepared by free radical polymerization of phosphonic ester acrylate monomers. Liberation of the free acid functions was realized by ester cleavage with Me3SiBr and the subsequent hydrolysis with methanol. The obtained polymers were analyzed by NMR and IR spectroscopy. The ion exchange capacity of the phosphonic acid functionalized methacrylate polymer was determined to 2.8 mmol/g by titration with 0.1 M NaOH. The proton conductivity under anhydrous conditions was determined to 6.84 × 10−6 Scm−1 at 120°C by electrochemical impedance spectroscopy. [ABSTRACT FROM AUTHOR]

Compounds exhibiting main group elements in low oxidation states were found to mimic the reactivity of transition metal complexes. Like the latter, such main group species show a proclivity of changing their oxidation state as well as their coordination number by +2, therefore fulfilling the requirements for oxidative additions. Prominent examples of such main group compounds that undergo oxidative additions with organohalides R−X (R=alkyl, aryl, X=F, Cl, Br, I) are carbenes and their higher congeners. Aluminyl anions, which like carbenes and silylenes oxidatively add to strong σ‐bonds in R−X species, have been recently discovered. We present the first anion based upon a Group 14 element, namely the tris(pentafluoroethyl)silanide anion, [Si(C2F5)3]−, which is capable of oxidative additions towards C−F bonds. This enables the isolation of non‐chelated tetraorganofluorosilicate salts, which to the best of our knowledge had only been observed as reactive intermediates before. [ABSTRACT FROM AUTHOR]

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Phosphoranides are interesting hypervalent species which serve as model compounds for intermediates or transition states in nucleophilic substitution reactions at trivalent phosphorus substrates. Herein, the syntheses and properties of stable trifluoromethylphosphoranide salts are reported. [K(18‐crown‐6)][P(CF3)4], [K(18‐crown‐6)][P(CF3)3F], and [NMe4][P(CF3)2F2] were obtained by treatment of trivalent precursors with sources of CF3− or F− units. These [P(CF3)4‐nFn]− (n=0–2) salts exhibit fluorinating (n=1–2) or trifluoromethylating (n=0) properties, which is disclosed by studying their reactivity towards selected electrophiles. The solid‐state structures of [K(18‐crown‐6)][P(CF3)4] and [K(18‐crown‐6)][P(CF3)3F] are ascertained by single crystal X‐ray crystallography. The dynamics of these compounds are investigated by variable temperature NMR spectroscopy. [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 renaissance of Brønsted superbases is primarily based on their pronounced capacity for a large variety of chemical transformations under mild reaction conditions. Four major set screws are available for the selective tuning of the basicity: the nature of the basic center (N, P, ...), the degree of electron donation by substituents to the central atom, the possibility of charge delocalization, and the energy gain by hydrogen bonding. Within the past decades, a plethora of neutral electron‐rich phosphine and phosphazene bases have appeared in the literature. Their outstanding properties and advantages over inorganic or charged bases have now made them indispensable as auxiliary bases in deprotonation processes. Herein, an update of the chemistry of basic phosphines and phosphazenes is given. In addition, due to widespread interest, their use in catalysis or as ligands in coordination chemistry is highlighted. [ABSTRACT FROM AUTHOR]

According to a first view on the geometrical and electronic structure of the tris(pentafluoroethyl)silanide, this anion appears as a Lewis base. Quantum chemical calculations on perfluoroalkylated silanides show significantly lower HOMO and LUMO energy levels in comparison to their non‐fluorinated counterparts, which implies reduced Lewis basicity and increased Lewis acidity of the [Si(C2F5)3]− ion. With these findings and a HOMO–LUMO gap of 4.80 eV similar to N‐heterocyclic silylenes (NHSis), perfluoroalkyl silanides are predestined to exhibit Lewis‐amphoteric character similar to silylenes. Deprotonation of Si(C2F5)3H with sterically demanding phosphazene bases afforded thermally stable phosphazenium salts of the [Si(C2F5)3]− anion, which add to benzaldehyde, benzophenone, CS2, and CO2 in various manners. This behavior also mirrors the reactivity of silylenes towards ketones as well as heterocumulenes and is rationalized by Lewis amphotericity being inherent in these silanides. [ABSTRACT FROM AUTHOR]

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In this work, the syntheses of non‐coordinated electron‐rich phenolate anions via deprotonation of the corresponding alcohols with an extremely powerful perethyl tetraphosphazene base (Schwesinger base) are reported. The application of uncharged phosphazenes renders the selective preparation of anionic phenol‐phenolate and phenolate hydrates possible, which allows for the investigation of hydrogen bonding in these species. Hydrogen bonding brings about decreased redox potentials relative to the corresponding non‐coordinated phenolate anions. The latter show redox potentials of up to −0.72(1) V vs. SCE, which is comparable to that of zinc metal, thus qualifying their application as organic zinc mimics. We utilized phenolates as reducing agents for the generation of radical anions in addition to the corresponding phenoxyl radicals. A tetracyanoethylene radical anion salt was synthesized and fully characterized as a representative example. We also present the activation of sulfur hexafluoride (SF6) with phenolates in a SET reaction, in which the nature of the respective phenolate determines whether simple fluorides or pentafluorosulfanide ([SF5]−) salts are formed. [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]

We report on the molecular structure of trimethylsilanes Si(CH3)3X in which the substituents X, namely (Z)‐pentafluoropropen‐1‐yl, trifluoropropyn‐1‐yl, pentafluoroethyl, trifluorovinyl, vinyl, propyn‐1‐yl, di‐ and trichloromethyl, display electron withdrawing effects of varying strength. The lengths of the bonds between the silicon and the carbon atoms of X correlate with the hybridization of the respective orbitals and the steric demand of X rather than with the electron withdrawing capability. In case of chlorinated substituents dispersion effects seem to shorten the Si−C bond. Furthermore, a route for generating trifluoropropyn‐1‐yllithium from the cryogen 2,3,3,3‐tetrafluoropropene (HFO‐1234yf) and n‐butyllithium is described. Tetrafluoropropen‐1‐yllithium is slowly formed at −80 °C but even at this temperature spontaneous elimination of LiF occurs. Deprotonation of the formed 3,3,3‐trifluoropropyne requires temperatures of above −60 °C leading to trifluoropropyn‐1‐yllithium which appears as relatively stable at room temperature. [ABSTRACT FROM AUTHOR]

We herein report on iminium salts derived from Ishikawa's reagent Et2N‐CF2‐CHF‐CF3. The reaction with P(C2F5)3F2 afforded [Et2N=CF‐CHF‐CF3][P(C2F5)3F3] as an ionic liquid. The fluorine atom in the cation in α position to the nitrogen atom is labile towards nucleophilic substitution as demonstrated by the reaction with SnCl2 where an exchange of the fluorine by a chlorine atom took place. Upon contact with water the fluorine atom is substituted by a hydroxyl group. The reaction of Ishikawa's reagent with P(C2F5)2F afforded the zwitterionic [P(C2F5)2F3{C(NEt2)(CHF‐CF3)}]. Most likely [Et2N=CF‐CHF‐CF3][P(C2F5)2F2] was formed transiently. The anion is obviously sufficiently nucleophilic to attack the susceptible α‐fluorine atom of the cation. During several months Ishikawa's reagent loses hydrogen fluoride, which reacts with glass producing SiF4 which abstracts a fluoride ion from Ishikawa's reagent affording [Et2N=CF‐CHF‐CF3][SiF5]. [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]

A convergent approach for the incorporation of tetrafluoroaryl phosphonate moieties into cyclic triphosphazenes and linear phosphazene resins is described. Our high yield procedure is based on the treatment of chlorinated poly‐ and cyclotriphosphazenes with p‐HO(C6F4)P(O)(OR)2 (R = Me, Et) in the presence of potassium carbonate. Characterization of the modified cyclotriphosphazenes was accomplished by NMR and IR spectroscopy as well as by mass spectrometry. Similarly, a phosphazene resin decorated with phosphonic esters is characterized by NMR and IR spectra and GPC. Exchange of the ethyl group by a trimethylsilyl group in the novel phosphazene derivatives was effected by the reaction with trimethylsilyl bromide. The resulting silyl phosphonates were converted into the corresponding phosphonic acids by exposure to an excess of methanol. Proton conductivities of the novel phosphonic acid derivatives of poly‐ and cyclotriphosphazenes were studied by electrochemical impedance spectroscopy under anhydrous conditions. [ABSTRACT FROM AUTHOR]

While perfluorinated aryl, aryloxy and alkoxy aluminum species are well‐established as weakly coordinating anions (WCAs), corresponding perfluoroalkyl aluminum derivatives are virtually unknown. Reaction of Si(C2F5)3CH3 with Li[AlH4] afforded the tetrakis(pentafluoroethyl)aluminate, [Al(C2F5)4]−. Several salts of the [Al(C2F5)4]− ion were synthesized and characterized by NMR spectroscopic methods, mass spectrometry, X‐ray diffraction studies and elemental analysis. [ABSTRACT FROM AUTHOR]

In this contribution we report on fluorotrimethyl[(Z)‐pentafluoropropen‐1‐yl]phosphorane as a phosphorus based fluorinating reagent. Its solid state structure can be described as a trigonal bipyramid featuring elongated axial bonds due to the formation of a 3‐center 4‐electron bond. Abstraction of the fluoride ion leads to a shortening of the axial P–C bond. Thus the title compound can be utilized for substitution of bromine with fluorine and for the transfer of fluoride ions onto electrophilic compounds. Reaction with Sn(C2F5)2Br2 afforded salt [P(CH3)3(C3F5)]2[Sn(C2F5)2F4]. When fluorotrimethyl[(Z)‐pentafluoropropen‐1‐yl]phosphorane was treated with P(C2F5)2F the primarily produced anion is sufficiently nucleophilic to attack the propenyl group of the cation in β‐position to the phosphorus atom to yield zwitterionic [Me3PCF=C(CF3)–PF3(C2F5)2]. [ABSTRACT FROM AUTHOR]

We report on the first examples of isolated silanol–silanolate anions, obtained by utilizing weakly coordinating phosphazenium counterions. The silanolate anions were synthesized from the recently published phosphazenium hydroxide hydrate salt with siloxanes. The silanol–silanolate anions are postulated intermediates in the hydroxide‐mediated polymerization of aryl and alkyl siloxanes. The silanolate anions are strong nucleophiles because of the weakly coordinating character of the phosphazenium cation, which is perceptible in their activity in polysiloxane depolymerization. [ABSTRACT FROM AUTHOR]

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The reaction of a strongly basic phosphazene (Schwesinger base) with water afforded the corresponding metastable hydroxide trihydrate [OH(OH2)3]− salt. This is the first hydroxide solvate that is not in contact with a cation and furthermore one of rare known water‐stabilized hydroxide anions. Thermolysis in vacuum results in the decomposition of the hydroxide salt and quantitative liberation of the free phosphazene base. This approach was used to synthesize the Schwesinger base from its hydrochloride salt after anion exchange in excellent yields of over 97 %. This deprotonation method can also be used for the phosphazene‐base‐catalyzed preparation of the Ruppert–Prakash reagent Me3SiCF3 using fluoroform (HCF3) as the trifluoromethyl building block and sodium hydroxide as the formal deprotonation agent. [ABSTRACT FROM AUTHOR]

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Electron‐withdrawing substituents R in complexes [Ln M(PR2)] influence the P–M bond length due to a decreased σ‐donation and enhanced π‐back‐bonding, leading to an increased Lewis acidity of the metal ion and therefore strengthening the M–L bond to electron‐rich ligands L. This influences the Lewis acidity and the redox behavior of corresponding transition‐metal complexes, which is important for the design of optimized catalytic systems. To investigate this effect, the electron‐poor phosphanes R2PH with R = C2F5, C6F5, 2,4‐(CF3)2C6H3 were treated with Pd(F6acac)2 (F6acac = hexafluoroacetylacetonato) and Pd(acac)2 (acac = acetylacetonato). While the reaction of the phosphanes with Pd(F6acac)2 in all cases yielded the corresponding phosphido‐bridged dinuclear palladium complexes [{(F6acac)Pd[µ‐(PR2)]}2], the compounds obtained in the reaction with Pd(acac)2 were structurally more diverse. For R = C2F5, the dinuclear palladium complex [{(acac)Pd{µ‐[P(C2F5)2]}}2] was obtained, while the reaction with (C6F5)2PH yielded a trinuclear palladium complex bridged by four phosphido units. All complexes were fully characterized, including X‐ray crystallography. [ABSTRACT FROM AUTHOR]

The reaction of [GaCl3(OEt2)n] with LiC2F5 surprisingly leads to the formation of the anion [Ga(C2F5)3Cl]–. The obtained lithium and tetraphenylphosphonium salts are useful starting materials for new pentafluoroethylgallium compounds. [PPh4][Ga(C2F5)3Cl] was conveniently transformed into [PPh4][Ga(C2F5)3X] (X = F, Br, I) with HF, NaBr, and NaI. Treatment of [Li(OEt2)n][Ga(C2F5)3Cl] with aqueous hydrogen chloride gives rise to the tris(pentafluoroethyl)gallane adduct [Ga(C2F5)3{(OH2)(OEt2)}]. Thermolysis of [Li(OEt2)n][Ga(C2F5)3Cl] affords another tris(pentafluoroethyl)gallane adduct, [Ga(C2F5)3(OEt2)], which can be converted into [Ga(C2F5)3(dmap)] (dmap = 4‐dimethylaminopyridine). [Ga(C2F5)3(OEt2)] as well as [Ga(C2F5)3(dmap)] react with [PPh4]Cl to [PPh4][Ga(C2F5)3Cl] and with HF to [HDMAP][Ga(C2F5)3F]. Both [Ga(C2F5)3(OEt2)] and [Ga(C2F5)3(dmap)] are precursors for the previously reported weakly coordinating anion [Ga(C2F5)4]–. Characterizations of the new compounds were carried out by NMR and IR spectroscopy, mass spectrometry, X‐ray diffraction and elemental analyses. [ABSTRACT FROM AUTHOR]

Weakly coordinating anions (WCAs) are important for academic reasons as well as for technical applications. Tetrakis(pentafluoroethyl)gallate, [Ga(C2F5)4]−, a new WCA, is accessible by treatment of [GaCl3(dmap)] (dmap=4‐dimethylaminopyridine) with LiC2F5. The anion [Ga(C2F5)4]− proved to be reluctant towards deterioration by aqueous hydrochloric acid or lithium hydroxide. Various salts of [Ga(C2F5)4]− were synthesized with cations such as [PPh4]+, [CPh3]+, [(O2H5)2(OH2)2]2+, and [Li(dec)2]+ (dec=diethyl carbonate). Thermolysis of [(O2H5)2(OH2)2][Ga(C2F5)4]2 gives rise to a dihydrate of tris(pentafluoroethyl)gallane, [Ga(C2F5)3(OH2)2]. All products were characterized by NMR and IR spectroscopy, mass spectrometry, X‐ray diffraction, and elemental analysis. Furthermore, an outlook for the application of [Li(dec)2][Ga(C2F5)4] as a conducting salt in lithium‐ion batteries is presented. [ABSTRACT FROM AUTHOR]

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In this contribution we present an account on pentafluoroethylated compounds of silicon, germanium and tin. The pronounced electron‐withdrawing effect of the pentafluoroethyl group leads to a markedly increased Lewis acidity at the central atom which results in the stabilization of hypervalent complexes, anionic element(II) species as well as remarkable reactivities of element‐element and element‐hydrogen bonds. By addition to unsaturated C−C bonds or by reaction with organic halides as well as transition‐metal complexes the molecules bearing a pentafluoroethyl‐element group are readily accessible. Moreover, the utilization of pentafluoroethyl groups facilitates the formation of donor‐stabilized germylenes and stannylenes. A series of such compounds serves as suitable pentafluoroethylation reagents. Conversely to the well‐studied trifluoromethyl derivatives these compounds frequently exhibit a higher thermostability, which allows a more convenient handling. The introduction of electron‐withdrawing pentafluoroethyl groups into organosilicon, organogermanium and organotin compounds creates a pronounced electron‐deficiency at the central atom, which leads to a significantly different chemical behavior with respect to non‐fluorinated derivatives. These characteristics facilitate the formation of hypervalent complexes, stabilization of low‐valent species as well as main group and transition‐metal complexes. [ABSTRACT FROM AUTHOR]

In this contribution the syntheses of transition metal complexes of the electron‐withdrawing Sn(C2F5)3 ligand are presented. The reaction of HSn(C2F5)3 with organometallics LnM–R (M = Zn, W, Mo; R = Et, Me; L = CO, Cp), metal carbonyls [Ni(CO)4], and [{Fe(CO)2Cp}2], as well as chloro complexes such as [TiCl2Cp2], furnished the corresponding stannylated compounds. The electron‐deficient Sn(C2F5)3 ligand significantly influences the IR spectroscopic and structural features with respect to related non‐fluorinated stannyl complexes. [ABSTRACT FROM AUTHOR]

The treatment of phenyl‐protected pentafluoroethylstannanes, Sn(C2F5)4–nPhn (n = 1–3), with anhydrous HF results in the formation of the corresponding fluorostannanes which are associated in the solid state but form monomeric and dimeric fluoride complexes in solution. Due to the pronounced Lewis acidity caused by the electron‐withdrawing pentafluoroethyl groups, these stannanes represent suitable precursors for the synthesis of neutral, monoanionic and dianionic hexacoordinate tin(IV) complexes. The employment of an excess of cesium fluoride and 1,10‐phenanthroline exclusively leads to the octahedral complexes [Sn(C2F5)nF6–n]2– (n = 2–4) and [Sn(C2F5)nF4–n(phen)] (n = 1–3). The addition of bases, donating solvents as well as LiF, on the other hand, selectively affords salts containing dinuclear anions of the form [(C2F5)3Sn(µ‐F)3Sn(C2F5)3]– and [(C2F5)2F2Sn(µ‐F)2SnF2(C2F5)2]2–. [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]

A versatile two-step synthesis of tris(pentafluoroethyl)stannane, HSn(C2F5)3, is presented. Electron-withdrawing C2F5 groups significantly influence the polarity of the tin–hydrogen bond, which allows facile deprotonation of the compound, even in water. The utility of this electron-deficient stannane was illustrated in hydrostannylations of alkenes and alkynes, as well as in dehalogenation reactions. The remarkably high reactivity of HSn(C2F5)3 is demonstrated in fast hydrostannylations, even in the absence of activators, whereby the regioselectivity of this process turns out to be solvent dependent. It is of great advantage that in dehalogenation reactions volatile halogenotris(pentafluoroethyl)stannanes, XSn(C2F5)3 (X=I, Br), are formed that allow facile separation of the tin-containing byproducts from the reaction mixtures. [ABSTRACT FROM AUTHOR]

Abstract: A versatile two‐step synthesis of tris(pentafluoroethyl)stannane, HSn(C2F5)3, is presented. Electron‐withdrawing C2F5 groups significantly influence the polarity of the tin–hydrogen bond, which allows facile deprotonation of the compound, even in water. The utility of this electron‐deficient stannane was illustrated in hydrostannylations of alkenes and alkynes, as well as in dehalogenation reactions. The remarkably high reactivity of HSn(C2F5)3 is demonstrated in fast hydrostannylations, even in the absence of activators, whereby the regioselectivity of this process turns out to be solvent dependent. It is of great advantage that in dehalogenation reactions volatile halogenotris(pentafluoroethyl)stannanes, XSn(C2F5)3 (X=I, Br), are formed that allow facile separation of the tin‐containing byproducts from the reaction mixtures. [ABSTRACT FROM AUTHOR]

Facile replacement of the p-fluorine atom in bis(diethylamino) pentafluorophenylphosphane [(Et2N)2PC6F5] by organolithium derivatives LiR (R = CH3, n-Bu, Ph), lithium alkoxides (R = OMe, OEt) and amides (NMe2, NEt2) is described. The obtained phosphanes p-R-C6F4-P(NEt2)2 are fully characterized. Their acid-catalyzed hydrolysis affords the corresponding phosphinic acids p-R-C6F4-P(O)(H)OH, which are smoothly oxidized by treatment with a mixture of DMSO/I2 to phosphonic acids p-R-C6F4-P(O)(OH)2. [ABSTRACT FROM AUTHOR]

The reaction of the industrial product (C2F5)3PF2 with LiAlH4 in THF solution selectively furnished the hydridophosphate anion [P(C2F5)3F2H]-. The compound [PPh4][P(C2F5)3F2H] is obtained as a colorless solid on a multigram scale by salt metathesis in aqueous THF. Combining [P(C2F5)3F2H]- with various imidazolium and pyridinium cations affords ionic liquids with melting points well below room temperature. (C2F5)3PF2 also abstracts hydrides from amines, affording the hydridophosphate anion [P(C2F5)3F2H]- and the corresponding imminium cations which add a second amine moiety by intra- or intermolecular adduct formation. [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]

In this paper, the synthesis of perfluoroorganotin bromides featuring 2,3,5,6-tetrafluoropyridyl (C5F4N) and pentafluoroethyl (C2F5) substituents of the general composition BrSn(C2F5)n(C5F4N)3–n (n = 0–2) is discussed. The utilization of the p-tolyl unit as a protecting group and LiC5F4N and LiC2F5 as perfluoroarylation and alkylation reagents allows a stepwise sequence of deprotection with HX (X = Cl, Br) and substitution to afford heteroleptic stannanes with three different substituents. In the solid state, BrSn(C5F4N)3 and BrSn(C2F5)(C5F4N)2 readily add water or acetonitrile and increase their coordination numbers. These results emphasize the Lewis acidic character of such perfluoroorganotin halides. [ABSTRACT FROM AUTHOR]

Syntheses of salts containing the tris(pentafluoroethyl)stannate(II) ion, [Sn(C2F5)3]−, were achieved through deprotonation of the corresponding stannane, HSn(C2F5)3, as well as by direct pentafluoroethylation of SnCl2 with LiC2F5. The electron-withdrawing substituents have substantial influence on the stability and reactivity of the anion as documented by its treatment with main group halides. Alkyl halides (R−X) underwent nucleophilic substitutions to afford RSn(C2F5)3, whereas Si, Ge, Sn, P halides gave rise to oxidation processes yielding hypervalent [SnX2(C2F5)3]− salts (X=Cl, Br, I). Moreover the unsymmetrical distannane, nBu3SnSn(C2F5)3, was disclosed as an alternative precursor for the Sn(C2F5)3 moiety. Although neither the solid state structure nor its spectra in alkane solution reveal unexpected peculiarities, unusual dissociation of the compound in coordinating solvents into [ nBu3Sn(D) n]+ and [Sn(C2F5)3]− ions was observed. [ABSTRACT FROM AUTHOR]

Owing to the highly electron-withdrawing C2F5 groups, the tris(pentafluoroethyl)germane (C2F5)3GeH represents an interesting Brønsted acidic compound. The germane is accessible by the treatment of the corresponding halogenogermanes (C2F5)3GeX (X=Cl, Br) with Bu3SnH. After clarifying its molecular structure in the solid state by X-ray diffraction, the acidity of (C2F5)3GeH was examined by treatment with different bases, for example, 1,8-bis(dimethylamino)naphthalene. The resulting germanate(II) ion [Ge(C2F5)3]− serves as a germyl group transfer reagent. The reaction with main-group and transition-metal complexes or organohalides opens access to a variety of different compounds, the structures of which were mostly determined by X-ray diffraction. The corresponding tricarbonylnickelate(0) complex [(CO)3NiGe(C2F5)3]− also gives information about the π-acceptor properties of the [Ge(C2F5)3]− ligand. Furthermore, hydrogermylation reactions of (C2F5)3GeH with alkynes afforded different stereoisomers (α,β- cis, β- trans) depending on the respective reaction conditions and substrates. [ABSTRACT FROM AUTHOR]