Search

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 [PPh 4 ]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., (© 2024 The Author(s). Chemistry - A European Journal published by Wiley-VCH GmbH.)

The reaction of [Ga(C 2 F 5 ) 3 (FSiMe 3 )] with chlorotrimethylsilane leads to the selective substitution of the α-fluorine atoms by chlorine atoms and thus to the formation of [Ga(CCl 2 CF 3 ) 3 (FSiMe 3 )]. The corresponding chlorogallate ion, [Ga(CCl 2 CF 3 ) 3 Cl] - , could be isolated and structurally characterized as its tetraphenylphosphonium salt. The catalytic potential of [Ga(CCl 2 CF 3 ) 3 (FSiMe 3 )] was demonstrated via the chlorodefluorination of Me 3 SiCF 3 , 2,2-difluoropropane and [PPh 4 ][Ga(C 2 F 5 ) 4 ]., (© 2024 The Author(s). Chemistry - A European Journal published by Wiley-VCH GmbH.)

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, [MR 4 ] - , behave as weakly coordinating anions, neutral gallanes and indanes, MR 3 , are strong Lewis acids. Salts with the tetrakis(pentafluoroethyl)gallate and -indate, [M(C 2 F 5 ) 4 ] - (M=Ga, In), have recently been studied in detail. In contrast to this, work on the syntheses of the free Lewis superacids M(C 2 F 5 ) 3 (M=Ga, In) is scarce and underdeveloped. The hydrates [M(C 2 F 5 ) 3 (OH 2 ) 2 ] proved to be suitable starting materials, particularly due to their thermal stability. Herein we report on synthesis and characterization of reactive adducts, [M(C 2 F 5 ) 3 D], with the weak donor molecules (D) SOCl 2 and Me 3 SiF. The effective Lewis acidities of Ga(C 2 F 5 ) 3 and In(C 2 F 5 ) 3 were experimentally determined by the (modified) Gutmann-Beckett method and their catalytic potential is showcased., (© 2024 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

Phosphoranides comprising three phosphorus carbon bonds are scarcely represented in the literature. We now utilized tris(pentafluoroethyl)phosphane, P(C 2 F 5 ) 3 , and cyanobis(pentafluoroethyl)phosphane, P(C 2 F 5 ) 2 (CN), featuring electron withdrawing pentafluoroethyl groups, to synthesize such compounds. Metal fluorides MF (M=Ag, Cs) add to P(C 2 F 5 ) 3 yielding respective M[P(C 2 F 5 ) 3 F] salts. Those M[P(C 2 F 5 ) 3 F] subsequently suffer a loss of C 2 F 4 , furnishing M[P(C 2 F 5 ) 2 F 2 ]. The cesium salt decomposes instantaneously when warmed to rt, whereas the silver salt decomposes slowly over several days at rt. Treatment of Ag[P(C 2 F 5 ) 3 F] with 2,2'-bipyridine facilitated the isolation and structural characterization of [Ag(bipy){P(C 2 F 5 ) 3 F}]. With P(C 2 F 5 ) 2 (CN), AgF reacts under substitution of the cyano group yielding P(C 2 F 5 ) 2 F, rather than phosphoranide formation. However, [K(18-crown-6)]F adds to P(C 2 F 5 ) 2 (CN) furnishing [K(18-crown-6)][P(C 2 F 5 ) 2 (CN)F]. Its structural characterization was successful, despite its tendency to undergo an exchange of substituents, yielding [K(18-crown-6)][P(C 2 F 5 ) 2 F 2 ] and presumably [K(18-crown-6)][P(C 2 F 5 ) 2 (CN) 2 ]. The latter forms an equilibrium with [K(18-crown-6)]CN and P(C 2 F 5 ) 2 (CN) which lies well on side of the phosphane and cyanide salt., (© 2023 The Authors. ChemPlusChem published by Wiley-VCH GmbH.)

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(C 2 F 5 ) 4 ] - , and its characterization in salts with the cations [Li(thf) 3 ] + , Cs + , [PPh 4 ] + and [H 14 O 6 ] 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., (© 2023 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)

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(C 2 F 5 ) 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., (© 2022 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

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(CF 3 ) 4 ], [K(18-crown-6)][P(CF 3 ) 3 F], and [NMe 4 ][P(CF 3 ) 2 F 2 ] were obtained by treatment of trivalent precursors with sources of CF 3 - or F - units. These [P(CF 3 ) 4-n F n ] - (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(CF 3 ) 4 ] and [K(18-crown-6)][P(CF 3 ) 3 F] are ascertained by single crystal X-ray crystallography. The dynamics of these compounds are investigated by variable temperature NMR spectroscopy., (© 2022 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)

We synthesized new imidazolium-based tunable aryl alkyl ionic liquids (TAAILs) with the weakly coordinating tetrakis(pentafluoroethyl)gallate anion, [Ga(C 2 F 5 ) 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(C 2 F 5 ) 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., (© 2021 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)

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(C 2 F 5 ) 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(C 2 F 5 ) 3 O] - . In order to examine such Lewis amphoteric behavior, we first developed a strategy for the synthesis of the corresponding silanol Si(C 2 F 5 ) 3 OH, which readily condenses at room temperature to the hexakis(pentafluoroethyl)disiloxane, (C 2 F 5 ) 3 SiOSi(C 2 F 5 ) 3 . Deprotonation of Si(C 2 F 5 ) 3 OH employing a sterically demanding phosphazene base allows the characterization of the first example of a dimeric triorganosilanolate: the dianionic hexakis(pentafluoroethyl)disilanolate, [{Si(C 2 F 5 ) 3 O} 2 ] 2- , implies Lewis amphoteric character of the monomeric [Si(C 2 F 5 ) 3 O] - anion., (© 2021 The Authors. Published by Wiley-VCH GmbH.)

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., (© 2021 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)

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(C 2 F 5 ) 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(C 2 F 5 ) 3 H with sterically demanding phosphazene bases afforded thermally stable phosphazenium salts of the [Si(C 2 F 5 ) 3 ] - anion, which add to benzaldehyde, benzophenone, CS 2 , and CO 2 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., (© 2021 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

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 (SF 6 ) with phenolates in a SET reaction, in which the nature of the respective phenolate determines whether simple fluorides or pentafluorosulfanide ([SF 5 ] - ) salts are formed., (© 2020 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)

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 [H 5 C 6 -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 SF 6 . The performed two-electron reduction of SF 6 leads to phosphazenium pentafluorosulfanide ([SF 5 ] - ) and fluoride salts., (© 2020 The Authors. Published by Wiley-VCH GmbH.)

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., (© 2020 The Authors. Published by Wiley-VCH GmbH.)

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(C 2 F 5 ) 3 CH 3 with Li[AlH 4 ] afforded the tetrakis(pentafluoroethyl)aluminate, [Al(C 2 F 5 ) 4 ] - . Several salts of the [Al(C 2 F 5 ) 4 ] - ion were synthesized and characterized by NMR spectroscopic methods, mass spectrometry, X-ray diffraction studies and elemental analysis., (© 2020 The Authors. Published by Wiley-VCH GmbH.)

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., (© 2019 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.)

The reaction of a strongly basic phosphazene (Schwesinger base) with water afforded the corresponding metastable hydroxide trihydrate [OH(OH 2 ) 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 Me 3 SiCF 3 using fluoroform (HCF 3 ) as the trifluoromethyl building block and sodium hydroxide as the formal deprotonation agent., (© 2019 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.)

Weakly coordinating anions (WCAs) are important for academic reasons as well as for technical applications. Tetrakis(pentafluoroethyl)gallate, [Ga(C 2 F 5 ) 4 ] - , a new WCA, is accessible by treatment of [GaCl 3 (dmap)] (dmap=4-dimethylaminopyridine) with LiC 2 F 5 . The anion [Ga(C 2 F 5 ) 4 ] - proved to be reluctant towards deterioration by aqueous hydrochloric acid or lithium hydroxide. Various salts of [Ga(C 2 F 5 ) 4 ] - were synthesized with cations such as [PPh 4 ] + , [CPh 3 ] + , [(O 2 H 5 ) 2 (OH 2 ) 2 ] 2+ , and [Li(dec) 2 ] + (dec=diethyl carbonate). Thermolysis of [(O 2 H 5 ) 2 (OH 2 ) 2 ][Ga(C 2 F 5 ) 4 ] 2 gives rise to a dihydrate of tris(pentafluoroethyl)gallane, [Ga(C 2 F 5 ) 3 (OH 2 ) 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(C 2 F 5 ) 4 ] as a conducting salt in lithium-ion batteries is presented., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

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., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Acetonitrile is deprotonated by a combination of the strong Lewis acid (C 2 F 5 ) 3 PF 2 and triethylamine. The resulting cyanomethyl function is bound to the phosphorus moiety, affording the highly stable salt [HNEt 3 ][P(C 2 F 5 ) 3 F 2 (CH 2 CN)]. Salt metathesis reactions furnished the corresponding [Cu(MeCN) 2 ] + and [Ag(MeCN)] + derivatives in which the CH 2 CN substituent of the anion [P(C 2 F 5 ) 3 F 2 (CH 2 CN)] - coordinates to the metal. An investigation of the gas separation capability of the silver salt [Ag(MeCN)][P(C 2 F 5 ) 3 F 2 (CH 2 CN)] shows an uptake of 1.7 equivalents of isobutene from a propane/isobutene mixture. The reaction of (C 2 F 5 ) 3 PF 2 with acetonitrile and diethylamine furnishes [P(C 2 F 5 ) 3 F 2 {NHC(CH 3 )NEt 2 }]-a phosphate featuring an amidine ligand which formally results from hydroamination of acetonitrile by HNEt 2 . Exchange of HNEt 2 with the primary amines H 2 NPh and H 2 NBu leads to comparable amidine salts that exhibit a solvent-dependent conformational isomerism., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

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(C 2 F 5 ) 3 {Sn(C 2 F 5 ) 3 }] - (X=Cl, Br, I, Sn(C 2 F 5 ) 3 ) derived from hexakis(pentafluoroethyl)distannane. NMR investigations at low temperature lend further mechanistic insights. Thus, by detection of the imposing ion [Sn(C 2 F 5 ) 3 {Sn(C 2 F 5 ) 3 } 2 ] - , one can surmise that the chemistry of Sn 2 (C 2 F 5 ) 6 has more in common with the isolobal iodine than with classical distannanes., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

In this contribution we report on the synthesis of bis(pentafluoroethyl)stannane, H 2 Sn(C 2 F 5 ) 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(C 2 F 5 ) 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(C 2 F 5 ) 2 (dmap) 2 ], treatment with PMe 3 or [Sn(C 2 F 5 ) 3 ] - furnished the corresponding neutral or anionic monoadducts, [Sn(C 2 F 5 ) 2 (D)] (D=PMe 3 , [Sn(C 2 F 5 ) 3 ] - ). In contrast, the utilization of sterically demanding donors, such as iPr 2 O, as well as the thermal treatment of ether complexes, [Sn(C 2 F 5 ) 2 (D) n ] (D=Et 2 O, THF), leads to the formation of oligomeric and cyclic stannylene moieties [Sn(C 2 F 5 ) 2 ] n . The reactivity of H 2 Sn(C 2 F 5 ) 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., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A versatile two-step synthesis of tris(pentafluoroethyl)stannane, HSn(C 2 F 5 ) 3 , is presented. Electron-withdrawing C 2 F 5 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(C 2 F 5 ) 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(C 2 F 5 ) 3 (X=I, Br), are formed that allow facile separation of the tin-containing byproducts from the reaction mixtures., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Pentafluoroethyllithium, LiC 2 F 5 , 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 LiCF 3 . The usual production of LiC 2 F 5 , however, from gaseous HC 2 F 5 or IC 2 F 5 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 LiC 2 F 5 from the already commercialized stannate salt [PPh 4 ][Sn(C 2 F 5 ) 5 ]. The [Sn(C 2 F 5 ) 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(C 2 F 5 ) 4 . The reaction of the latter with n-butyllithium provides an insight into the mechanism of LiC 2 F 5 generation., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Syntheses of salts containing the tris(pentafluoroethyl)stannate(II) ion, [Sn(C 2 F 5 ) 3 ] - , were achieved through deprotonation of the corresponding stannane, HSn(C 2 F 5 ) 3 , as well as by direct pentafluoroethylation of SnCl 2 with LiC 2 F 5 . 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(C 2 F 5 ) 3 , whereas Si, Ge, Sn, P halides gave rise to oxidation processes yielding hypervalent [SnX 2 (C 2 F 5 ) 3 ] - salts (X=Cl, Br, I). Moreover the unsymmetrical distannane, nBu 3 SnSn(C 2 F 5 ) 3 , was disclosed as an alternative precursor for the Sn(C 2 F 5 ) 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 [nBu 3 Sn(D) n ] + and [Sn(C 2 F 5 ) 3 ] - ions was observed., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Owing to the highly electron-withdrawing C 2 F 5 groups, the tris(pentafluoroethyl)germane (C 2 F 5 ) 3 GeH represents an interesting Brønsted acidic compound. The germane is accessible by the treatment of the corresponding halogenogermanes (C 2 F 5 ) 3 GeX (X=Cl, Br) with Bu 3 SnH. After clarifying its molecular structure in the solid state by X-ray diffraction, the acidity of (C 2 F 5 ) 3 GeH was examined by treatment with different bases, for example, 1,8-bis(dimethylamino)naphthalene. The resulting germanate(II) ion [Ge(C 2 F 5 ) 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) 3 NiGe(C 2 F 5 ) 3 ] - also gives information about the π-acceptor properties of the [Ge(C 2 F 5 ) 3 ] - ligand. Furthermore, hydrogermylation reactions of (C 2 F 5 ) 3 GeH with alkynes afforded different stereoisomers (α,β-cis, β-trans) depending on the respective reaction conditions and substrates., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

For (pentafluoroethyl)phenylstannanes, (C 2 F 5 ) 4-n  SnPh n (n=1-3), and dimethylbis(pentafluoroethyl)stannane, (C 2 F 5 ) 2 SnMe 2 , a high yield synthesis was developed by the use of LiC 2 F 5 as a C 2 F 5 transfer reagent. The treatment of these products with gaseous hydrogen chloride or hydrogen bromide afforded (C 2 F 5 ) 4-n SnX n (X=Cl, Br; n=1-3) in good yields. The (pentafluoroethyl)stannanes were fully characterized by 1 H, 13 C, 19 F and 119 Sn NMR, IR spectroscopy and mass spectrometry. The treatment of the (pentafluoroethyl)tin halides (C 2 F 5 ) 4-n SnX n with 1,10-phenanthroline (phen) led to the formation of the corresponding octahedrally coordinated complexes [(C 2 F 5 ) 4-n SnX n (phen)], the structures of which were elucidated by X-ray diffraction analyses. The bromostannane (C 2 F 5 ) 3 SnBr reacted with sodium cyclopentadienide to give the (η 1 -cyclopentadienyl)tris(pentafluoroethyl)stannane, (C 2 F 5 ) 3 SnCp, for which single-crystal X-ray diffraction analysis could be performed. The coupling constants 1 J( 119 Sn, 13 C) and 2 J( 119 Sn, 19 F) 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., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Commercially available BiPh 3 was treated with perfluoroalkylphosphinic acids [for example, (C 2 F 5 ) 2 P(O)OH] to generate novel, highly Lewis acidic bismuth(III) perfluoroalkylphosphinates of the type Ph x Bi[R F 2 PO 2 ] 3-x (x=0, 1, 2) (R F =-C 2 F 5 , -C 4 F 9 ). The first bismuth(V) perfluoroalkylphosphinate, Ph 3 Bi[(C 2 F 5 ) 2 PO 2 ] 2 , was synthesized from Ph 3 BiCl 2 and Ag[(C 2 F 5 ) 2 PO 2 ]. Examples for the successful application of the catalytically active bismuth(III) and bismuth(V) phosphinates in carbon-carbon bond forming reactions, such as Friedel-Crafts acylation and alkylation, Diels-Alder, Strecker and Mannich reaction, are presented., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A series of tris-, bis-, and mono(pentafluoroethyl)bismuthanes of the type (C 2 F 5 ) n BiX 3-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 C 2 F 5 groups, are described for representative examples. Moreover, the first molecular structures of perfluoroalkyl bismuthanes and bismuthates obtained by X-ray diffraction are presented., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The tris(pentafluoroethyl)silanide anion is accessible by the deprotonation of Si(C 2 F 5 ) 3 H 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(C 2 F 5 ) 3 ] as a powerful nucleophilic transfer reagent., (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Tris(pentafluoroethyl)silane, which is conveniently accessible by the treatment of Si(C 2 F 5 ) 3 X (X=Cl, Br) with Bu 3 SnH, was successfully employed for hydrosilylation reactions. In the presence of a palladium catalyst, hydrosilylation of phenylacetylene with Si(C 2 F 5 ) 3 H 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., (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Pure anhydrous hexafluorosilicic acid (H 2 [SiF 6 ]) 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(C 2 F 5 ) n X 4-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., (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

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. (C 2 F 5 ) 2 Si(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., (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

This paper gives an account on hypervalent fluoro- and chloro(pentafluoroethyl)germanium compounds. The selective synthesis of the tris(pentafluoroethyl)dichlorogermanate salt [PNP][(C 2 F 5 ) 3 GeCl 2 ] 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 [C 23 H 17 O][(C 2 F 5 ) 3 GeF 2 ] is reported. Fluoride-ion affinities for pentafluoroethylgermanes were calculated using quantum chemical methods, disclosing (C 2 F 5 ) 3 GeF as a weaker Lewis acid than (C 2 F 5 ) 3 SiF or (C 2 F 5 ) 3 PF 2 . The theoretical results were confirmed by experiments and give the basis of a synthetic protocol for (C 2 F 5 ) 3 GeF. Pentakis(pentafluoroethyl)germanate [PPh 4 ][Ge(C 2 F 5 ) 5 ] was detected as an intermediate during the synthesis of [PPh 4 ][(C 2 F 5 ) 4 GeF] starting from tris(pentafluoroethyl)difluorogermanate and LiC 2 F 5 ., (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The synthesis of the germylene phosphane adduct (C2 F5 )2 Ge⋅PMe3 is described. Starting from (C2 F5 )3 GeH in an excess of PMe3 , heating was applied, whereupon reductive elimination of C2 F5 H 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(C2 F5 )2 (PMe3 )}] in the CO region. (C2 F5 )2 Ge⋅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 [(C2 F5 )2 Cl2 Ge-CH2 PMe3 ], which was fully characterized by X-ray diffraction., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The chemistry of bis(pentafluoroethyl)germanes (C2F5)2 GeX2 is presented. The synthesis of such species requires Br2 GePh2 , wherein the phenyl substituents function as suitable protecting groups. After treatment with two equivalents of LiC2 F5, (C2F5)2 GePh2 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)2 GeO]3 results from the reaction of (C2F5)2 GeBr2 with Ag2 CO3. Its crystalline 1,10-phenanthroline adduct was fully characterised by X-ray diffraction. The combination of (C2F5)2 GeBr2 with Bu3 SnH gave rise to the formation of (C2F5)2 GeH2 ., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The synthesis of tris(pentafluoroethyl)germanium derivatives is described. The reaction of germanium tetrachloride with three equivalents of the pentafluoroethylation reagent LiC 2 F 5 does not lead selectively to the formation of tris(pentafluoroethyl)chlorogermane, (C 2 F 5 ) 3 GeCl. Here the introduction of a diethylamino function as a protecting group was beneficial. Thus, treatment of Cl 3 GeNEt 2 with LiC 2 F 5 smoothly afforded (C 2 F 5 ) 3 GeNEt 2 . The replacement of the amino substituent by halides was accomplished by reaction with HBr or HCl on a multigram scale. The combination of (C 2 F 5 ) 3 GeCl with Ag 2 CO 3 gave rise to the formation of the digermoxane [(C 2 F 5 ) 3 Ge] 2 O. 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, (C 2 F 5 ) 3 GeOH, and water., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Phosphinic acids, R(f)P(O)(OH)H (R(f)=CF3, C2F5, C6F5), turned out to be excellent preligands for the coordination of phosphonous acids, R(f)P(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 [R(f)P(OH)O](-) and R(f)P(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., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

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 C2F5 P(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., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The addition of BCl3 to the carbene-transfer reagent NHC→SiCl4 (NHC=1,3-dimethylimidazolidin-2-ylidene) gave the tetra- and pentacoordinate trichlorosilicon(IV) cations [(NHC)SiCl3 ](+) and [(NHC)2 SiCl3 ](+) with tetrachloroborate as counterion. This is in contrast to previous reactions, in which NHC→SiCl4 served as a transfer reagent for the NHC ligand. The addition of BF3 ⋅OEt2 , on the other hand, gave NHC→BF3 as the product of NHC transfer. In addition, the highly Lewis acidic bis(pentafluoroethyl)silane (C2 F5 )2 SiCl2 was treated with NHC→SiCl4 . In acetonitrile, the cationic silicon(IV) complexes [(NHC)SiCl3 ](+) and [(NHC)2 SiCl3 ](+) were detected with [(C2 F5 )SiCl3 ](-) as counterion. A similar result was already reported for the reaction of NHC→SiCl4 with (C2 F5 )2 SiH2 , which gave [(NHC)2 SiCl2 H][(C2 F5 )SiCl3 ]. If the reaction medium was changed to dichloromethane, the products of carbene transfer, NHC→Si(C2 F5 )2 Cl2 and NHC→Si(C2 F5 )2 ClH, respectively, were obtained instead. The formation of the latter species is a result of chloride/hydride metathesis. These compounds may serve as valuable precursors for electron-poor silylenes. Furthermore, the reactivity of NHC→SiCl4 towards phosphines is discussed. The carbene complex NHC→PCl3 shows similar reactivity to NHC→SiCl4 , and may even serve as a carbene-transfer reagent as well., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Chlorosilicates represent important intermediates in S(N)2 reactions of chlorosilanes. They can be stabilized by the introduction of electron-withdrawing substituents. Salts of various (pentafluoroethyl)chlorosilicates have been isolated and structurally characterized., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

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., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

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 , C6 F5 , C6 H5 ) with LiC2 F5 . On treatment with para-toluenesulfonic acid the isolated aminophosphanes R(C2 F5 )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 )(C2 F5 )POH as a stable phosphinous acid, whereas the pentafluorophenyl and phenyl derivatives constitute a solvent dependent equilibrium between the acid and the oxide tautomer., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A new efficient synthesis of functionalized perfluoroalkyl fluorophosphates by oxidative addition of Me2NCH2F to the electron-deficient phosphanes (C2F5)(n)PF(3-n) (n=0-3) is reported. The initially formed zwitterionic, hexacoordinated phosphates [(C2F5)(n)F(5-n)P(CH2NMe2-CH2NMe2)] are converted into the corresponding phosphonium salts [(Me3PCH2NMe2](+)[(C2F5)(n)F(5-n)P(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., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

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)3 CF3 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)3 NEt2 is a valuable precursor for a series of tris(pentafluoroethyl)silanes., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The research area of perfluoroalkylsilanes is still in its infancy. Although there are already many examples of difluorotriorganylsilicates, the first example of a completely characterized trifluorotriorganylsilicate is presented, the dianion [Si(C2 F5 )3 F3 ](2-) . The strongly electron-withdrawing influence of the pentafluoroethyl groups appears to be a fundamental cause of the stability of this compound. This dianion is also the first structurally characterized example of a tris(pentafluoroethyl)silicon compound. The synthesis and complete characterization of [PPh4 ]2 [Si(C2 F5 )3 F3 ] and [PPh4 ][Si(C2 F5 )3 F2 ] along with the precursor [H(OEt2 )2 ][Si(C2 F5 )3 F2 ] was achieved from SiCl4 and LiC2 F5 ., (Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Secondary phosphane oxides, R(2)P(O)H, are commonly used as preligands for transition-metal complexes of phosphinous acids, R(2)P-OH (R=alkyl, aryl), which are relevant as efficient catalysts in cross-coupling processes. In contrast to previous work by other groups, we are interested in the ligating properties of an electron-deficient phosphinous acid, (R(f))(2)P-OH, bearing the strongly electron-withdrawing and sterically demanding 2,4-bis(trifluoromethyl)phenyl group towards catalysis-relevant metals, such as palladium and platinum. The preligand bis[2,4-bis(trifluoromethyl)phenyl]phosphane oxide, (R(f))(2)P(O)H, reacts smoothly with solid platinum(II) dichloride yielding the trans-configured phosphinous acid platinum complex trans-[PtCl(2)({2,4-(CF(3))(2)C(6)H(3)}(2)POH)(2)]. The deprotonation of one phosphinous acid ligand with an appropriate base leads to the cis-configured monoanion complex cis-[PtCl(2)({2,4-(CF(3))(2)C(6)H(3)}(2)PO)(2)H](-), featuring the quasi-chelating phosphinous acid phosphinito unit, (R(f))(2)P-O-H···O=P(R(f))(2), which exhibits a strong hydrogen bridge substantiated by an O···O distance of 245.1(4) pm. The second deprotonation step is accompanied by a rearrangement to afford the trans-configured dianion trans-[PtCl(2)({2,4-(CF(3))(2)C(6)H(3)}(2)PO)(2)](2-). The reaction of (R(f))(2)P(O)H with solid palladium(II) dichloride initially yields a mononuclear palladium complex [PdCl(2)({2,4-(CF(3))(2)C(6)H(3)}(2)POH)(2)], which condenses under liberation of HCl to the neutral dinuclear palladium complex [Pd(2)(μ-Cl)(2){({2,4-(CF(3))(2)C(6)H(3)}(2)PO)(2)H}(2)]. The equilibrium between the mononuclear [PdCl(2)({2,4-(CF(3))(2)C(6)H(3)}(2)POH)(2)] and dinuclear [Pd(2)(μ-Cl)(2){({2,4-(CF(3))(2)C(6)H(3)}(2)PO)(2)H}(2)] palladium complexes is reversible and can be shifted in each direction by the addition of base or HCl, respectively. Treatment of palladium(II) hexafluoroacetylacetonate, [Pd(F(6)acac)(2)], with a slight excess of (R(f))(2)P(O)H yields the complex [Pd(F(6)acac)({2,4-(CF(3))(2)C(6)H(3)}(2)PO)(2)H]. The quasi-chelating phosphinous acid phosphinito unit, which is formed by the liberation of HF(6)acac, is characterized by a O···O distance of 244.1(3) pm. These transition metal complexes are stable towards air and moisture and can be stored for months without any evidence of decomposition., (Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

(C(2)F(5))(2)PCl is now accessible through a significantly improved synthesis protocol starting from the technical product (C(2)F(5))(3)PF(2). (C(2)F(5))(3)PF(2) was reduced in the first step with NaBH(4) in a solvent-free reaction at 120 °C. The product, P(C(2)F(5))(3), was treated with an excess of an aqueous sodium hydroxide solution to afford the corresponding phosphinite salt Na(+)(C(2)F(5))(2)PO(-) selectively under liberation of pentafluoroethane. Subsequent chlorination with PhPCl(4) resulted in the selective formation of (C(2)F(5))(2)PCl, which was isolated by fractional condensation in an overall yield of 66 %. The gas electron diffraction (GED) pattern for (C(2)F(5))(2)PCl was recorded and found to be described by a two-conformer model. A quantum chemical investigation of the potential-energy surface revealed the possible existence of many low-energy conformers, each with a number of low-frequency vibrational modes and therefore large-amplitude motions. The conformer calculated to be most stable was also found to be most abundant by GED and comprised 61(5) % of the total. The molecular structure parameters determined by GED were in good agreement with those calculated at the MP2/TZVPP level of theory; the only significant difference was a discrepancy of about 3° in the C-P-C angle, which, for the lowest-energy conformer, was refined to 98.2(4)° and was calculated to be 94.9°., (Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)