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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]

Abstract: The electron withdrawing effect of a variety of differently substituted phenyl groups can be classified on the basis of the C:glyph name="sbnd" />N distance of the corresponding phenolate or aryl amide ions (Ar–O− and Ar–NH−), respectively, which are reliably accessible by DFT calculations on B3LYP/6-311+G(2d,p) level of theory. An increasing electron withdrawing effect of the aromatic group leads to a shortened Ce:glyph name="sbnd" />N distance of the corresponding ions. Within the presented model it is also possible to characterize the electronic nature of different kinds of six membered heterocycles. The defined constants Δ(E) m,p – the difference of the E–C distances of the substituted derivatives X-C6H4-E and the non-substituted phenyl derivative, C6H5-E – exhibit the same tendency as the corresponding Hammett constants. The values of Δ(E) m,p strongly depend on the nature of E. With E=F, the resulting values Δ(F) m,p are found to be accidentally close to the corresponding Hammett constants. Therefore, the values of Δ(E) m,p , which can be easily determined by DFT calculations, are useful tools to classify the electronic nature of different kinds of substituents. The different electronic nature of the groups E, for example O−, NH− or F, gives rise to varying electronic interactions with the connected aromatic ring system. These interactions influence on their part the special interaction of a given substituent X. This is the reason why the constants Δ(E) m,p exhibits different values, which vary depending on the different electronic nature of the groups E. As a consequence, the values Δ(E) m,p open the possibility to classify the electronic nature of substituents X in relation to any neutral or even charged group E. [Copyright &y& Elsevier]

Abstract: The electronic properties of organyl element compounds are strongly influenced by the electronic characteristics of the organic substituents. The bonding of two CF3 groups to a phosphorus atom effects a drastically decreased basicity. That is the phosphorus atom is the least basic centre in the compound (CF3)2POH. This compound, synthesized in 1960 by Burg and Griffiths, is the only known example of a phosphinous acid, although there should be a general interest in this class of compounds. However, only a few investigations have been reported which may be explained by the tedious and risky synthesis. In this paper a safe one step and high yield synthesis of (CF3)2POH is described. The compound (C6F5)2POH, originally claimed as a phosphinous acid, is proved to exist at room temperature exclusively in the tautomeric oxide form. (C6F5)2P(O)H crystallizes in the triclinic space group (no. 2) with a 992.9(1) pm; b 1501.9(2) pm; c 1539.4(2) pm; α 117.48(1)°; β 100.39(1)°; γ 96.02(1)° and Z 6. Quantum chemical investigations prove the electron withdrawing effect of s-triazinyl groups (1,3,5-triazin-4-yl derivatives) to be much stronger than that of pentafluorophenyl groups. Quantum chemical calculations at the B3PW91/6-311G(3d,p) level of theory predict for the bis(s-triazinyl) derivative (C3N3H2)2POH the phosphinous acid isomer to be favored by ΔE ZP =22 kJ/mol in relation to the corresponding phosphane oxide isomer. The phosphinous acid (CF3)2POH (Cs symmetry) is favored at the same level of theory by about ΔE ZP =14 kJ/mol compared with the phosphane oxide structure (Cs symmetry). [Copyright &y& Elsevier]

The first example of a mononuclear diphosphanidoargentate, bis{bis(trifluoromethyl)phosphanido}argentate, [Ag{P(CF3)2}2] , is obtained via the reaction of HP(CF3)2 with [Ag(CN)2]- and isolated as its [K(18-crown-6)] salt. When the cyclic phosphane (PCF3)4 is reacted with a slight excess of [K(18-crown-6)][Ag{P(CF3)2}2], selective insertion of one PCF3 unit into each silver phosphorus bond is observed, which on the basis of NMR spectroscopic evidence suggests the [Ag{P(CF3)P(CF3)2}2]- ion. On treatment of the phosphane complexes [M(CO)5PH(CF3)2] (M = Cr, W) with [K(18-crown-6)][Ag(CN)2], the analogous trinuclear argentates, [Ag{(µ-P(CF3)2)M(CO)5}2]-, are formed. The chromium compound [K(18-crown-6)][Ag{(µ-P(CF3)2)Cr(CO)5}2] crystallizes in a noncentrosymmetric space group Fdd2 (No. 43), a = 2970.2(6) pm, b = 1584.5(3) pm, c = 1787.0(4), V= 8.410(3) nm³, Z = 8. The symmetric anion, [Ag{(µ-P(CF3)2)Cr(CO)5}2]-, shows a nearly linear arrangement of the P-Ag-P unit. Although the bis(pentafluorophenyl)phosphanido compound [Ag{P(C6F5)2}2]- has not been obtained so far, the synthesis of its trinuclear counterpart, [K(18-crown-6)][Ag{(µ-P(C6F5)2)W(CO)5}2], was successful. ub>)2)W(CO)5}2]-: X-ray Crystal Structure of [K(18-crown-6)][Ag{(μ-P(CF3)2)Cr(CO)5}2]. [ABSTRACT FROM AUTHOR]

Synthetic routes to vanadium(V)-phosphinimide derivatives aro addressed. Initial synthetic efforts afforded the known compound formulated as VCI[sub 2](NPPh[sub 3])[sub 3] which was crystallographically determined to be the salt [VCI(NPPh[sub 3])[sub 3]]CI (1). Reactions of the vanadium-imide precursors VCI[sub 3](NAr) (Ar = Ph, C[sub 6]H[sub 3]-2,6-iPr[sub 2]) with R[sub 3]PNSiMe[sub 3] (R = Ph, iPr, tBu) afforded VCl[sub 2](NPh)(NPPh[sub 3]) (4), VCl[sub 2](NPh)(NPiPr[sub 3]) (5), VCl[sub 2](NPh)(NP tBu[sub 3]) (6), VCl[sub 2](NC[sub 6]H[sub 3]-2,6-iPr[sub 2])(NPPh[sub 3]) (7), VCI[sub 2](NC[sub 6]H[sub 3]-2,6-iPr[sub 2])(NP iPr[sub 3]) (8), and VCI[sub 2](NC[sub 6]H[sub 3]-2,6-iPr[sub 2])(NPtBu[sub 3]) (9) in yields ranging from 72% to 84%. Subsequent alkylation or arylation reactions resulted in VMe2(NC[sub 6]H[sub 3]-2,6-iPr[sub 2])(NPtBu[sub 3]) (10), VPh[sub 2](NPh)(NP tBu[sub 3]) (11), VPh[sub 2](NC[sub 6]H[sub 3]-2,6-iPr[sub 2])(NP iPr[sub 3]) (12), and VPh[sub 2](NC[sub 6]H[sub 3]-2,6-iPr[sub 2])(NPtBu[sub 3]) (13) while substitution reactions with Li[N(SiMe[sub 3])[sub 2]] and Li[SBn] gave VCI(N(SiMe[sub 3])[sub 2](NPh)(NPtBu[sub 3]) (14) and V(SBn)[sub 2](NC[sub 6]H[sub 3]-2,6iPr[sub 2])(NPtBu[sub 3]) (15)in yields ranging from 40% to 49% yield. Polarization of the N-P phosphinimide bond and V-N multiple bond character are evidenced by crystallographic data. [ABSTRACT FROM AUTHOR]

The stabilization of the P(CF[sub 3])[sub 2][sup -] ion by intermediary coordination to the very weak Lewis acid acetone gives access to single crystals of [18-crown-6-K]P(CF[sub 3])[sub 2]. The X-ray single crystal analysis exhibits nearly isolated P(CF[sub 3])[sub 2][sup -] ions with an unusually short P-C distance of 184(1) pm, which can be explained by negative hyperconjugation and is also found by quantum chemical hybrid DFT calculation. Coordination of the P(CF[sub 3])[sub 2][sup -] ion to pentacarbonyl tungsten has only a minor effect on electronic and geometric properties of the P(CF[sub 3])[sub 2] moiety, while a strong increase in thermal stability of the dissolved species is achieved. The hitherto unknown P(C[sub 6]F[sub 5])[sub 2][sup -] ion is stabilized by coordination to pentacarbonyl tungsten and isolated as a stable 18-crown-6 potassium salt, [18-crown-6-K][W{P(C[sub 6]F[sub 5])[sub 2]}(CO)[sub 5]], which is fully characterized. The tungstate, [W{P(C[sub 6]F[sub 5])[sub 2]}(CO)[sub 5]]-, decomposes slowly in solution, while coordination of the phosphorus atom to a second pentacarbonyl tungsten moiety results in an enhanced thermal stability in solution. The single-crystal X-ray analysis of [18-crown-6-K][{W(CO)[sub 5]}[sub 2]{µ-P(C[sub 6]F[sub 5])[sub 2]}].THF exhibits a very tight arrangement of the two C[sub 6]F[sub 5] and two W(CO)[sub 5] groups around the central phosphorus atom. NMR spectroscopic investigations of the [{W(CO)[sub 5]}[sub 2]{µ-P(C[sub 6]F[sub 5])[sub 2]}]-ion exhibit a hindered rotation of both the C[sub 6]F[sub 5] and W(CO)[sub 5] groups in solution. [ABSTRACT FROM AUTHOR]

The use of Bu[sub 3]SnH and Me[sub 3]SnH in the synthesis of HP(CF[sub 3])[sub 2] and HP(C[sub 6]F[sub 5])[sub 2] from the corresponding bromides leads to a high-yield synthesis, which additionally provides these compounds in large quantities. The pentacarbonyl tungsten complexes [W(CO)[sub 5]PH(CF[sub 3])[sub 2]] and [W(CO)[sub 5]PH(C[sub 6]F[sub 5])[sub 2]] were synthesized reacting the corresponding phosphanes with [W(CO)[sub 5]THF] and characterized by X-ray and elemental analysis as well as multinuclear NMR and mass spectroscopy. The vibrational analyses of HP(CF[sub 3])[sub 2] and HP(C[sub 6]F[sub 5])[sub 2] and their tungsten pentacarbonyl complexes were achieved in combination with hybrid DFT calculations. The optimized structures of [W(CO)[sub 5]PH(CF[sub 3])[sub 2]] and [W(CO)[sub 5]PH(C[sub 6]F[sub 5])[sub 2]] at the B3PW91 level of theory using a LanL2DZ basis and ECP at the tungsten atom and a 6-311G(3d,p) and 6-311G(d,p) basis set for the nonmetal atoms, respectively, yield an impressively good agreement between experimental and theoretical geometric parameters. An increased π-acidity of HP(CF[sub 3])[sub 2] in comparison with HP(C[sub 6]F[sub 5])[sub 2] and HPPh[sub 2] is discussed in the context of vibrational analysis, X-ray structural investigations, and theoretical calculations. [ABSTRACT FROM AUTHOR]

Examines the stabilization of the P(CF[sub3])[sub2]-ion being a reversible CS[sub2] adduct. Uses being a nucleophilic P(CF[sub3])[sub2]-source; Thermal stability of the ion; Formation of the bis(trifluoromethyl)phosphanodithioformate anion.

Reports on the preparation and characterization of bis(trifluoromethyl)phosphanide ligand salts of outstanding stability. Importance of low coordinating cations in stabilizing the salts; Applicability as reagents for nucleophilic substitutions.

Reports on the synthesis and characterization of two mercury bis(trifluoromethyl)phosphanides and their phosphane complexes. Thermal stability; Crystallization and crystal structure; Coordination chemistry; Bond lengths; Isolation of the complexes.

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]

Studies the experimental and theoretical characteristics of the oxygen-coordinated donor-acceptor adducts of dihalocarbonyl compounds, COCL2, COClF and COF2 with AsF5 and SbF5. Instability of the adducts at ambient temperature; Use of dissociation pressure curves; Characteristic oxygen-coordinated donor-acceptor; Increased oxygen bridge strengths.

Discusses the thermally stability or unstability of silver. State at which silver is oxidized; Suitability of silver for certain identification by nuclear magnetic resonance techniques; Details on the study.

Describes the nuclear magnetic resonance (NMR) spectra of the cyano(trifluoromethyl)argentates(III) silver transition metal compounds. Use of multinuclear NMR spectroscopy; Identification of the stable and unstable trifluoromethyl substituted argentates(III); Examination of the structures of [PPh4][trans-Ag(CF3)2(CN)2] and [PPh4][Ag(CF3)3(CH3)].

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]

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]

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]

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]

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]

During our attempts to synthesize chiral bidentate bis(trifluoromethyl)phosphane containing ligands, we found a bis(trifluoromethyl)phosphanide induced formal insertion of acetone into tetrakis(trifluoromethyl)diphosphane. [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]

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]

Weakly coordinating anions (WCAs) are of great academic as well as industrial interest. To advance the fluoroalkyl phosphate anion [P(C2F5)3F3]-, which is ideally suited for technical applications, functional substituents X are attached to the Lewis acid (C2F5)3PF2. In keeping with this, the reaction of (C2F5)3PF2 with 4-(dimethylamino)pyridine (DMAP) yields the corresponding adduct [P(C2F5)3F2(dmap)]. Treatment of this adduct with Brønsted acids (HX) leads to the selective formation of the corresponding phosphate anions [P(C2F5)3F2X]- by trapping the proton with the liberated base DMAP. In this way, OH functions can be transformed in one step into WCAs, slightly increasing the coordination properties of the corresponding anion. An ion exchange to the corresponding [PPh4] salts results in solids, whereas the corresponding imidazolium salts are obtained as room-temperature ionic liquids. [ABSTRACT FROM AUTHOR]

Secondary phosphane oxides R2P(O)H are most frequently used as preligands for phosphinous acid R2POH (R = alkyl, aryl) transition-metal complexes, which are very efficient catalysts for cross-coupling reactions. To investigate the influence of electron-deficient substituents on the catalytic activity, the coordination properties of bis(trifluoromethyl)-, bis(pentafluoroethyl)-, and bis[2,4-bis(trifluoromethyl)phenyl]phosphinous acid toward catalytically relevant metals, such as palladium and platinum, are studied. The novel phosphinous acid palladium complexes reveal a high catalytic activity in Heck and Suzuki cross-coupling reactions. Because of the strong dependence of these processes on the reaction conditions, a systematic solvent and base screening with 1-bromo-3-fluorobenzene and phenyl boronic acid as model reactants is performed. The most efficient solvent/base system consists of 2-propanol and potassium phosphate, providing a full conversion and a TON of around 10 000 after 20 h at room temperature with a catalyst loading of 0.01 mol % palladium. A catalyst loading of only 0.004 mol % palladium still leads to a nearly full conversion after 20 h at room temperature. During the catalytic reaction, the formation of the corresponding phosphinic acid R2P(O)OH is observed. Further investigations lead to the conclusion that palladium nanoparticles represent the catalytically active species. We also succeeded in the generation of palladium nanoparticles, which exhibit an extremely high catalytic activity in Suzuki cross-coupling reaction with TONs over 60 000 and TOFs larger than 40 000. [ABSTRACT FROM AUTHOR]

Abstract: While reactions of AgC5F4N with elemental arsenic, antimony, and bismuth proceed selectively yielding E(C5F4N)3 (E=As, Sb, Bi), those with white and red phosphorus remained obscure giving product mixtures of so far unknown stoichiometry. The phosphorus compound was therefore prepared by an alternative route. P(C5F4N)3 and As(C5F4N)3 crystallize isostructurally in the monoclinic space group P21/c (no. 14) with four molecules per unit cell. π–π Offset stacking together with edge-face stacking lead to dimeric units which are connected by a second edge-face stacking of nitrogen onto the opposite side of the same tetrafluoropyridyl ring extending the structure into infinite chains. [Copyright &y& Elsevier]

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]

Verbindungen von Hauptgruppenelementen in niedrigen Oxidationsstufen sind in der Lage, die Reaktivität von Übergangsmetallkomplexen nachzuahmen. Wie Letztere neigen niedervalente Hauptgruppenelementverbindungen zur Änderung ihrer Oxidationsstufe und Koordinationszahl um +2, wodurch sie die wesentlichen Voraussetzungen für oxidative Additionen erfüllen. Prominente Beispiele für Hauptgruppenelementverbindungen, die mit Organohalogeniden R−X (R=Alkyl, Aryl, X=F, Cl, Br, I) oxidative Additionen eingehen, sind Carbene und ihre höheren Analoga. Kürzlich wurde auch über Aluminyl‐Anionen berichtet, die wie Carbene und Silylene starke σ‐Bindungen von R−X‐Spezies oxidativ addieren können. Hier stellen wir nun mit dem Tris(pentafluorethyl)silanid‐Anion, [Si(C2F5)3]−, das erste Anion aus der 14. Gruppe vor, welches C−F‐Bindungen im Sinne einer oxidativen Addition zu spalten vermag. Dies ermöglichte die Isolierung von nicht‐chelatierten Tetraorganofluorosilicat‐Salzen, die unseres Wissens bisher nur als reaktive Zwischenstufen nachgewiesen wurden. [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]

Bei Betrachtung der geometrischen und elektronischen Struktur des Tris(pentafluorethyl)silanids erscheint das Anion auf den ersten Blick als Lewis‐Base. Quantenmechanischen Rechnungen zufolge liegen die HOMO‐ und LUMO‐Energien von Perfluoralkylsilaniden deutlich niedriger als die nicht fluorierter Derivate. Dies hat eine geringere Lewis‐Basizität und zugleich eine erhöhte Lewis‐Acidität des [Si(C2F5)3]−‐Ions zur Folge. Mit diesen Erkenntnissen und einer der N‐heterocyclischen Silylenen (NHSis) ähnlichen HOMO‐LUMO‐Lücke von 4.80 eV sind Perfluoralkylsilanide dazu prädestiniert, Lewis‐amphoteres Verhalten ähnlich dem der Silylene aufzuweisen. Die Deprotonierung von Si(C2F5)3H mit sterisch anspruchsvollen Phosphazenbasen liefert thermisch stabile Phosphazenium‐Salze des [Si(C2F5)3]−‐Anions, welche in unterschiedlicher Weise an Benzaldehyd, Benzophenon, CS2 und CO2 addieren. Dieses Verhalten spiegelt die Reaktivität von Silylenen gegenüber Ketonen sowie Heterocumulenen wider und wird durch die Lewis‐Amphoterie des Silanids begründet. [ABSTRACT FROM AUTHOR]

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]

Wir berichten über die ersten Beispiele isolierter Silanol‐Silanolat‐Anionen unter Verwendung schwach koordinierender Phosphazenium‐Gegenionen. Die Silanolat‐Anionen wurden durch die Reaktion des kürzlich veröffentlichten Phosphazenium‐Hydroxid‐Hydrat‐Salzes mit Siloxanen synthetisiert. Die Silanol‐Silanolat‐Anionen sind postulierte Zwischenprodukte bei der Hydroxid‐vermittelten Polymerisation von Aryl‐ und Alkylsiloxanen. Die Silanolat‐Anionen sind wegen des schwach koordinierenden Charakters des Phosphazenium‐Kations starke Nucleophile. Diese Eigenschaft macht sich in ihrer Aktivität bei der Depolymerisation von Polysiloxanen bemerkbar. [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]