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Research has been conducted on the P(CF (sub)3) (sub)2 (super)- ion. The ability of this ion to stabilize in solution has been investigated and the results indicate that this feature can affect the ion's capability to be used in nucleophilic displacement reactions.

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]

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 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]

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]

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]

Research has been conducted on thermally unstable compound [Hg{P(C (sub)6 F (sub)5) (sub)2} (sub)2]. The authors report that this compound has been produced via the reaction of mercury cyanide with bis-(pentafluorophenyl)phosphane in N,N-dimethylformamide solution, and has been characterized via the use of multinuclear NMR spectroscopy.

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]

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]

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: 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]

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]

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]

Many approaches to introduce the CF2P(O)(OR)2 unit into organic molecules make use of CuI-catalyzed couplings between organic halides and BrZnCF2P(O)(OR)2. Despite the great importance of this process for the synthesis of α,α-difluoromethylenephosphonates, the constitution and molecular structures of the organozinc precursor and the catalytically relevant copper/zinc complex are still unknown. Here we report on the isolation of these two species, their spectroscopic characterization, and the determination of their structure by single-crystal X-ray diffraction. First orienting experiments on the stability of the cuprate reagent in solution at room temperature as well as its reactivity towards allyl bromides were subsequently performed. [ABSTRACT FROM AUTHOR]

Transfer hydrogenation plays an important part in organic chemistry. Recently, strong Lewis acids like B(C6F5)3 have been introduced as a catalyst for these reactions. We successfully employed the Lewis acid (C2F5)3PF2 as a catalyst in the transfer hydrogenation between 1,3,5-trimethylcyclohexa-1,4-diene and 1,1-diphenylethylene. Surprisingly, the treatment of the diene alone with a catalytic amount of (C2F5)3PF2 led to a quantitative dismutation to mesitylene and 1,3,5-trimethylcyclohexane. With B(C6F5)3, there was a solvent-dependency: in CH2Cl2 mainly the dismutation products were obtained, while in toluene the evolution of H2 was observed. Additionally, the catalytic activity of various perfluoroalkylated germanes and silanes was tested. [ABSTRACT FROM AUTHOR]

For (pentafluoroethyl)phenylstannanes, (C2F5)4− n SnPh n ( n=1-3), and dimethylbis(pentafluoroethyl)stannane, (C2F5)2SnMe2, a high yield synthesis was developed by the use of LiC2F5 as a C2F5 transfer reagent. The treatment of these products with gaseous hydrogen chloride or hydrogen bromide afforded (C2F5)4− nSnX n (X=Cl, Br; n=1-3) in good yields. The (pentafluoroethyl)stannanes were fully characterized by 1H, 13C, 19F and 119Sn NMR, IR spectroscopy and mass spectrometry. The treatment of the (pentafluoroethyl)tin halides (C2F5)4− nSnX n with 1,10-phenanthroline (phen) led to the formation of the corresponding octahedrally coordinated complexes [(C2F5)4− nSnX n(phen)], the structures of which were elucidated by X-ray diffraction analyses. The bromostannane (C2F5)3SnBr reacted with sodium cyclopentadienide to give the ( η 1-cyclopentadienyl)tris(pentafluoroethyl)stannane, (C2F5)3SnCp, for which single-crystal X-ray diffraction analysis could be performed. The coupling constants 1 J(119Sn,13C) and 2 J(119Sn,19F) of all new stannanes are strongly correlated and sensitive to the substitution pattern at the tin atom. For both coupling constants a negative sign could be assigned. [ABSTRACT FROM AUTHOR]

A series of tris-, bis-, and mono(pentafluoroethyl)bismuthanes of the type (C2F5) nBiX3- n (X=F, Cl, Br, I) and transition metal complexes are accessible by a sophisticated pentafluoroethylation protocol. Chemical properties, induced by the strongly electron-withdrawing character of C2F5 groups, are described for representative examples. Moreover, the first molecular structures of perfluoroalkyl bismuthanes and bismuthates obtained by X-ray diffraction are presented. [ABSTRACT FROM AUTHOR]

Tris(pentafluoroethyl)silane, which is conveniently accessible by the treatment of Si(C2F5)3X (X=Cl, Br) with Bu3SnH, was successfully employed for hydrosilylation reactions. In the presence of a palladium catalyst, hydrosilylation of phenylacetylene with Si(C2F5)3H affords the product of an α-addition whereas the reaction of trimethylsilylacetylene with the silane leads to the β- trans product. Tris(pentafluoroethyl)silane can be deprotonated by sterically demanding bases such as lithium diisopropylamide at low temperatures to give the corresponding silanide ion. The addition of crown ethers or cryptands to this highly reactive species enabled the isolation and characterization of salt-like tris(pentafluoroethyl)silanide at room temperature. [ABSTRACT FROM AUTHOR]

The tris(pentafluoroethyl)silanide anion is accessible by the deprotonation of Si(C2F5)3H at low temperatures. Subsequent quenching of the resulting salt-like compounds with suitable electrophiles, such as transition-metal complexes or Group 14 element halides, leads to a plethora of novel tris(pentafluoroethyl)silane derivatives. This underlines the versatility of Li[Si(C2F5)3] as a powerful nucleophilic transfer reagent. [ABSTRACT FROM AUTHOR]

As recently shown, the introduction of pentafluoroethyl functionalities into silicon compounds is of general interest due to an enhanced Lewis acidity of the resulting species. By this means, the synthesis of previously inaccessible hypervalent silicon derivatives is enabled. While an easy access to tris(pentafluoroethyl)silanes has already been published, synthetic strategies for the selective preparation of bis derivatives are yet unknown. In this contribution, a convenient protocol for the synthesis of functional bis(pentafluoroethyl)silicon compounds is presented. These compounds represent precursors for the synthesis of pentafluoroethylated polysiloxanes. Furthermore, they prove to be resistant to oxonium cations, which is a key feature for the preparation of stable pentafluoroethylsilic acids. Treatment of dichlorodiphenoxysilane with in situ generated pentafluoroethyl lithium leads to the corresponding bis(pentafluoroethyl)silane in high yields. (C2F5)2Si(OPh)2 serves as a starting material for further functionalized bis(pentafluoroethyl)silanes. These silanes have been isolated and their reactivity towards N bases studied. The pronounced Lewis acidity of the obtained compounds has been documented by the formation of octahedral adducts with nitrogen donors such as 1,10-phenanthroline and acetonitrile. [ABSTRACT FROM AUTHOR]

This paper gives an account on hypervalent fluoro- and chloro(pentafluoroethyl)germanium compounds. The selective synthesis of the tris(pentafluoroethyl)dichlorogermanate salt [PNP][(C2F5)3GeCl2] as well as its X-ray structural analysis is described. As a representative example for pentafluoroethylfluorogermanates, the synthesis and structure of 2,4,6-triphenylpyryliumtris(pentafluoroethyl)difluorogermanate [C23H17O][(C2F5)3GeF2] is reported. Fluoride-ion affinities for pentafluoroethylgermanes were calculated using quantum chemical methods, disclosing (C2F5)3GeF as a weaker Lewis acid than (C2F5)3SiF or (C2F5)3PF2. The theoretical results were confirmed by experiments and give the basis of a synthetic protocol for (C2F5)3GeF. Pentakis(pentafluoroethyl)germanate [PPh4][Ge(C2F5)5] was detected as an intermediate during the synthesis of [PPh4][(C2F5)4GeF] starting from tris(pentafluoroethyl)difluorogermanate and LiC2F5. [ABSTRACT FROM AUTHOR]

Fluoride ion affinities (FIA), provided by DFT calculations, are exceedingly useful for the design of new Lewis acids with defined reactivities. Herein, we report the synthesis, characterization and reactivity of new difluoro(perfluoroorganyl)phosphoranes, which readily abstract fluoride ions from difluoro(triorganyl)phosphoranes. Highly reactive fluorobismuthonium cations and the [Ph3Bi(NCCH3)2]2+ cation are accessible through the treatment of difluoro(triorganyl)bismuth(V) compounds with the Lewis acidic phosphoranes discussed here. [ABSTRACT FROM AUTHOR]

The synthesis of the germylene phosphane adduct (C2F5)2Ge⋅PMe3 is described. Starting from (C2F5)3GeH in an excess of PMe3, heating was applied, whereupon reductive elimination of C2F5H occurred. The molecular structure was ascertained by X-ray diffraction and compared with information obtained by quantum chemical methods. The ligand properties were derived by studying the IR spectrum of the nickel(0) complex [Ni(CO)3{Ge(C2F5)2(PMe3)}] in the CO region. (C2F5)2Ge⋅PMe3 turned out to be a π-accepting ligand comparable to PMe3, in terms of Tolman's electronic parameter. Furthermore a [2+4] cycloaddition reaction with 2,3-dimethyl-1,3-butadiene, and σ-bond insertion reactions were recorded. Activation of the C−Cl bond in dichloromethane gives rise to the formation of the phosphonium ylide complex [(C2F5)2Cl2Ge-CH2PMe3], which was fully characterized by X-ray diffraction. [ABSTRACT FROM AUTHOR]

The chemistry of bis(pentafluoroethyl)germanes (C2F5)2GeX2 is presented. The synthesis of such species requires Br2GePh2, wherein the phenyl substituents function as suitable protecting groups. After treatment with two equivalents of LiC2F5, (C2F5)2GePh2 is produced. The replacement of the phenyl rings is smoothly effected by gaseous HBr or HCl in the presence of a Lewis acidic catalyst. The trigermoxane [(C2F5)2GeO]3 results from the reaction of (C2F5)2GeBr2 with Ag2CO3. Its crystalline 1,10-phenanthroline adduct was fully characterised by X-ray diffraction. The combination of (C2F5)2GeBr2 with Bu3SnH gave rise to the formation of (C2F5)2GeH2. [ABSTRACT FROM AUTHOR]

The synthesis of tris(pentafluoroethyl)germanium derivatives is described. The reaction of germanium tetrachloride with three equivalents of the pentafluoroethylation reagent LiC2F5 does not lead selectively to the formation of tris(pentafluoroethyl)chlorogermane, (C2F5)3GeCl. Here the introduction of a diethylamino function as a protecting group was beneficial. Thus, treatment of Cl3GeNEt2 with LiC2F5 smoothly afforded (C2F5)3GeNEt2. The replacement of the amino substituent by halides was accomplished by reaction with HBr or HCl on a multigram scale. The combination of (C2F5)3GeCl with Ag2CO3 gave rise to the formation of the digermoxane [(C2F5)3Ge]2O. An obtuse Ge-O-Ge angle of 150.2(1)° was determined by X-ray diffraction. Attempted hydrolysis of the digermoxane leads to an equilibrium mixture of the precursor, (C2F5)3GeOH, and water. [ABSTRACT FROM AUTHOR]

Phosphinic acids, RfP(O)(OH)H (Rf=CF3, C2F5, C6F5), turned out to be excellent preligands for the coordination of phosphonous acids, RfP(OH)2. Addition of C2F5P(O)(OH)H to solid PtCl2 under different reaction conditions allows the isolation and full characterization of the mononuclear complexes [ClPt{P(C2F5)(OH)O}{P(C2F5)(OH)2}2] and [Pt{P(C2F5)(OH)O}2{P(C2F5)(OH)2}] containing hydrogen-bridged [RfP(OH)O]− and RfP(OH)2 units. Further deprotonation of [Pt{P(C2F5)(OH)O}2{P(C2F5)(OH)2}2] leads to the formation of the dianionic platinate, [Pt{P(C2F5)(OH)O}4]2−, revealing four intramolecular hydrogen bridges. With PdCl2 the dinuclear complex [Pd2(μ-Cl)2{[P(C2F5)(OH)O]2H}2] was isolated and characterized. The Cl− free complex [Pd{P(C2F5)(OH)O}2{P(C2F5)(OH)2}2] was also prepared and deprotonated to the dianionic palladate, [Pd{P(C2F5)(OH)O}4]2−. Both compounds were characterized by NMR spectroscopy, IR spectroscopy, and X-ray analyses. In addition, the C6F5 derivatives [ClPt{P(C6F5)(OH)O}{P(C6F5)(OH)2}2] and [Pd2(μ-Cl)2{[P(C6F5)(OH)O]2H}2] as well as the CF3 derivative [Pd2(μ-Cl)2{[P(CF3)(OH)O]2H}2] were synthesized and fully characterized. Phosphonous acid complexes are inert towards air and moisture and can be stored for several months without decomposition. The catalytic activity of the palladium complexes in the Suzuki cross-coupling reaction between 1-bromo-3-fluorobenzene and phenyl boronic acid was demonstrated. [ABSTRACT FROM AUTHOR]

Bis(diethylamino)pentafluoroethylphosphane represents a versatile starting material for the synthesis of functionalized pentafluoroethylphosphanes. Perfluoroalkyl substituted aminophosphanes themselves already exhibit interesting coordination properties and were treated with the catalytically relevant salts PtCl2 and PdCl2 affording trans-[Cl2M{P(C2F5)(NEt2)2}2]. The hitherto unknown (C2F5)PBr2, accessible in good yields by treatment of C2F5P(NEt2)2 with HBr, was smoothly transformed into the corresponding phosphane, C2F5PH2, or fluoro derivative, C2F5PF2. Acidic hydrolysis of C2F5P(NEt2)2 yielded the phosphinic acid C2F5P(O)(OH)H, the anion of which was structurally characterized. The phosphinic acid smoothly adds to the carbonyl group of acetone under PC bond formation. An analogous reaction with aldehydes, for example, salicyl aldehyde, offers the possibility to generate stereocenters. [ABSTRACT FROM AUTHOR]

Lithium carbenoids are versatile compounds for synthesis owing to their intriguing ambiphilic behavior. Although this class of compounds has been known for several years, few solid-state structures exist because of their high reactivity and often low thermal stability. Using cryo X-ray techniques, we were now able to elucidate the first solid-state structure of a Li/F alkyl carbenoid, pentafluoroethyllithium (LiC2F5), finally yielding a prototype for investigating structure-- reactivity relationships for this class of molecules. The compound forms a diethyl ether-solvated dimer bridged by a rare C-F-Li link. Complementary NMR spectroscopy studies in solution show dynamic processes and indicate rapid exchange of starting material and product. Theoretical investigations help to understand the formation of the observed unusual structural motif. [ABSTRACT FROM AUTHOR]

This paper describes the synthesis of unsymmetrically substituted phosphinous acids and phosphane oxides featuring at least one electron-withdrawing pentafluoroethyl group. The presence of a diethylamino function as a protecting group allows a selective reaction of RClPNEt2 (R=CF3, C6F5, C6H5) with LiC2F5. On treatment with para-toluenesulfonic acid the isolated aminophosphanes R(C2F5)PNEt2 are readily converted into the corresponding phosphinous acids or phosphane oxides, respectively. Investigation of the tautomeric equilibrium between oxide and acid tautomer revealed (CF3)(C2F5)POH as a stable phosphinous acid, whereas the pentafluorophenyl and phenyl derivatives constitute a solvent dependent equilibrium between the acid and the oxide tautomer. [ABSTRACT FROM AUTHOR]

A new efficient synthesis of functionalized perfluoroalkyl fluorophosphates by oxidative addition of Me2NCH2F to the electron-deficient phosphanes (C2F5) nPF3− n ( n=0-3) is reported. The initially formed zwitterionic, hexacoordinated phosphates [(C2F5) nF5− nP(CH2NMe2−CH2NMe2)] are converted into the corresponding phosphonium salts [(Me3PCH2NMe2]+[(C2F5) nF5− nP(CH2NMe2)]− by treatment with PMe3. In addition [(C2F5)3F2P(CH2NMe2CH2NMe2)] can undergo a 1,3-methyl shift from the internal to the terminal nitrogen-a structural characterization was achieved from the CF3 analogue. Reaction of [(C2F5)3F2P(CH2NMeCH2NMe3)] and PMe3 gave rise to the formation of the zwitterionic phosphonium phosphate [(C2F5)3F2P(CH2NMeCH2PMe3)], which was fully characterized by X-ray diffraction analysis. Moreover, an efficient one-pot synthesis of Cs+[(C2F5)3F2P(CH2NMe2)]− was pursued. This salt turned out to be a useful nucleophile in several alkylation reactions. [ABSTRACT FROM AUTHOR]

The synthesis and complete characterization of functional, highly Lewis acidic tris(pentafluoroethyl)silanes as well as tetrakis(perfluoroalkyl)silanes Si(C2F5)4 and Si(C2F5)3CF3 by direct fluorination is described. The reaction of SiCl4 with LiC2F5 invariably affords (pentafluoroethyl)fluorosilicates. To avoid silicate formation by fluoride transfer from LiC2F5 the Lewis acidity of the silane has to be decreased by electron-donating substituents, such as dialkylamino groups. The easily accessible Si(C2F5)3NEt2 is a valuable precursor for a series of tris(pentafluoroethyl)silanes. [ABSTRACT FROM AUTHOR]

(C2F5)2PNEt2 represents an excellent starting material for the selective synthesis of bis(pentafluoroethyl)phosphane derivatives. The moderately air-sensitive aminophosphane is accessible on a multi-gram scale by treating Cl2PNEt2 with C2F5Li. Treatment with gaseous HCl or HBr yielded the corresponding phosphane halides (C2F5)2PCl and the so far unknown (C2F5)2PBr in good yields. The hitherto unknown (C2F5)2PF was obtained by treating (C2F5)2PBr with excess antimony trifluoride. Treatment of (C2F5)2PCl with Bu3SnH led to the quantitative formation of (C2F5)2PH. Deprotonation formally yielded the (C2F5)2P- anion in a form that was stabilized by coordination to mercury ions to form the complex [Hg{P(C2F5)2}2(dppe)]. An improved high-yielding synthesis of (C2F5)2POH was achieved by treating (C2F5)2PNEt2 with p-toluenesulfonic acid. The gas-phase structures of (C2F5)2PH and (C2F5)2POH were determined by electron diffraction. The vibrational corrections employed in the data analysis of the diffraction data were derived from molecular dynamics calculations. Both compounds exist in the gas phase mostly as C1-symmetric cis, cis conformers with regard the orientation of the C2F5 groups relative to the functional groups H and OH. The presence of a second conformer at ambient temperature is likely in both cases. The refined amounts of dominant conformers are 94(6) and 85(6) % for (C2F5)2PH and (C2F5)2POH, respectively. The conformational behaviour was further explored by potential energy surface scans based on DFT calculations. Important experimental structural parameters for the most stable conformers are re(P-C)average = 1.884(3) Å for (C2F5)2PH and re(P-C)average = 1.894(4) Å and re(P-O) = 1.582(3) Å for (C2F5)2POH. The different coordination properties of (C2F5)3P, (C2F5)2POH, (CF3)3P and (CF3)2POH were evaluated by complex formation with [Ni(CO)4]: the maximum achievable number of CO ligands substituted by (C2F5)3P is 1, by (C2F5)2POH is 2, by (CF3)3P is 3 and by the smallest ligand (CF3)2POH is 4. [ABSTRACT FROM AUTHOR]

Pure anhydrous hexafluorosilicic acid (H2[SiF6]) is a still elusive species, although its existence in aqueous solutions is well documented. Desiccation inevitably leads to decomposition to form tetrafluorosilane and hydrogen fluoride. An oxonium hexafluorosilicate turned out to not be stable at room temperature. Partial substitution of the fluorine atoms with strong electron-withdrawing perfluoroalkyl groups results in substantial stabilization of the corresponding fluorosilicic acids. Mono- and bis(pentafluoroethyl)-substituted fluorosilicic acids were prepared through conversion of the respective halosilanes (Si(C2F5) nX4− n, with X=Cl, Br) with aqueous HF, and were obtained as colorless solids. They can be stored at room temperature for several months without decomposition, and thus are the first examples of stable fluorosilicic acids. [ABSTRACT FROM AUTHOR]

Fluorine, Oxidative Addition, Perfluorosilicates, Silanide Anion, Silicon Frontispiece: Oxidative Additions of C-F Bonds to the Silanide Anion [Si(C2F5)3]- Keywords: Fluorine; Oxidative Addition; Perfluorosilicates; Silanide Anion; Silicon EN Fluorine Oxidative Addition Perfluorosilicates Silanide Anion Silicon 1 1 1 04/14/22 20220419 NES 220419 B Silicon b In their Research Article (e202116468), Berthold Hoge et al. report oxidative additions of [Si(C SB 2 sb F SB 5 sb ) SB 3 sb ] SP - sp to aryl- and alkenylfluorides, enabling the isolation of tetraorganofluorosilicate salts devoid of chelating ligands. [Extracted from the article]

Silicon In their Research Article (e202116468), Berthold Hoge et al. report oxidative additions of [Si(C2F5)3]− to aryl‐ and alkenylfluorides, enabling the isolation of tetraorganofluorosilicate salts devoid of chelating ligands. [ABSTRACT FROM AUTHOR]

The introduction of electron‐withdrawing pentafluoroethyl groups into organosilicon, organogermanium and organotin compounds by the treatment of organo‐element halides with LiC2F5 creates a pronounced electron‐deficiency at the central atom with respect to non‐fluorinated derivatives. For silicon, germanium and tin reliable protocols for a cleavage of the organic protecting groups allow the synthesis of the Lewis acidic pentafluoroethyl‐element halides E(C2F5)4−nXn (E=Si, Ge, Sn; n=1–3). For a detailed discussion of this field of research see the Concept article by M. Wiesemann and B. Hoge on page 16457 ff. [ABSTRACT FROM AUTHOR]

In analogy to the proverbially uplifting influence of energy drinks, electron‐withdrawing substituents such as perfluoroorganyl groups can also boost the performance of element compounds. For example, pentafluoroethyl groups are very useful for increasing the Lewis acidity and for the stabilization of molecules with extraordinary bonding situations. Furthermore, these compounds in general exhibit a comparatively low boiling point, so that C2F5 groups even lend heavy metals, such as bismuth, wings! An efficient method is reported for the preparation of pentafluoroethyl bismuth compounds using LiC2F5 generated either by the deprotonation of HC2F5 with nBuLi or the combination of P(C2F5)3 and nBuLi. More information can be found in the Full Paper by B. Hoge et al. on page 1557 ff. [ABSTRACT FROM AUTHOR]

The cover page of the journal "Angewandte Chemie" is presented.

Main‐Group Chemistry The germanium awakens in the field of bis(pentafluoroethyl)germanes. Employing the phenyl group as a protecting group opens a straightforward synthetic route to (C2F5)2GePh2. To obtain functionalizable bis(pentafluoroethyl)germanes, the deprotection can be effected with gaseous HBr or HCl under the assistance of a Lewis acidic catalyst. The derivatization of the obtained halogenogermanes is described by the reactions with Ag2CO3 to obtain hexakis(pentafluoroethyl)trigermoxane and with Bu3SnH yielding (C2F5)2GeH2, studied by X‐ray diffraction. The complete story can be found in the Full Paper by B. Hoge and colleagues on page 4758 ff. [ABSTRACT FROM AUTHOR]