A new fluorinated anion for room-temperature ionic liquids

A new room-temperature ionic liquid (RTIL) consisting of the fluorinated anion bis(trifluoromethyl)-phosphinate((CF₃)₂PO₂⁻) coupled with the 1-butyl-3-methyl-imidazoliuim (BMIM) cation has been synthesized and characterized by physicochemical and electrochemical means including differential scanning calorimetry (DSC), thermogravimetric analysis, viscosity, conductivity and cyclic voltammetry measurements. Properties are compared with those of the known RTIL consisting of BMIM coupled with the bis(trifluoromethyl)-sulfonylimide (TFSI) anion.     

A Convenient,Selective Synthesis of Bis[2,4‐bis(trifluoromethyl)phenyl]phosphane Derivatives Starting from 1,3‐Bis(trifluoromethyl)benzene

The reaction of the sterically shielded phosphane derivative, dichlorodiethylaminophosphane, Cl₂PNEt₂, with an excess of a mixture of 2,6‐bis(trifluoromethyl) and 2,4‐bis(trifluoromethyl)phenyl lithium gives bis[2,4‐bis(trifluoromethyl)phenyl]diethylaminophosphane, [2,4‐(CF₃)₂C₆H₃]₂PNEt₂, in 72 % yield as a colourless solid, while 2,6‐bis(trifluoromethyl)phenyl lithium remains unchanged in solution. The amino derivative crystallizes in the monoclinic space group P2₁/c (a 869.2(1), b 1857.4(1), c 1357.6(1) pm, β 100.57(4)°, Z = 4). Treatment of [2,4‐(CF₃)₂C₆H₃]₂PNEt₂ in CHCl₃ solution with conc. HCl allows the synthesis of [2,4‐(CF₃)₂C₆H₃)]₂PCl. [2,4‐(CF₃)₂C₆H₃]₂PCl reacts with H₂O in THF solution with quantitative formation of the corresponding secondary phosphane oxide. To obtain bis[2,4‐bis(trifluoromethyl)phenyl]phosphinic acid, [2,4‐(CF₃)₂C₆H₃]₂P(O)OH, quantitatively, a CHCl₃ solution of [2,4‐(CF₃)₂C₆H₃]₂P(O)H, has to be stirred in an NO₂ atmosphere. The phosphinic acid crystallizes is the triclinic space group (a 754.2(1), b 927.6(2), c 1305.5(2) pm, α 85.11(2)°, β 75.45(1)°, γ 79.99(2)°, Z = 2). From the reaction of the phosphinic acid with either elemental sodium or with cyanide salts, the corresponding phosphinate salts are obtained in an almost quantitatively yield.     

Exchange reactions between O-nitrosobis(trifluoromethyl)hydroxylamine and M(CF3)3 (M = P,As and Sb)

O-Nitrosobis(trifluoromethyl)hydroxylamine gives novel reactions with tris(trifluoromethyl)-phosphine, -arsine and -stibine to affford mainly the corresponding bis(trifluoromethyl)nitroxol derivatives. Tris(trifluoromethyl) phosphine affords (CF₃)₂NOP(O)(CF₃)₂ and (CF₃)₂NNO. Tris(trifluoromethyl) arsine also gives (CF₃)₂NNO in high yield, together with smaller amounts of (CF₃)₂NOAs(CF₃)₂, CF₃NCF₂, COF₂ and a polymeric white solid. With tris(trifluoromethyl)stibine, no oxidation nor addition reactions occurred. Instead, [(CF₃)₂NO]₃Sb and [(CF₃)NO]₂SbCF₃ were obtained in high yields. The stoichiometry of the reactions suggests that the additional amounts of bis(trifluoromethyl)nitroxyl groups bonded to antimony are derived from the trifluoromethyl groups bonded to antimony. Mechanisms to rationalise these reactions are proposed.     

Novel Addition of Diphosphanes to Carbonyl Compounds

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.     

Synthesis of a functional C2-symmetrical bidentate diphenylphosphonite DIOP derivative and its conversion into the corresponding pi-acidic bis(pentafluorophenyl) and bis(p-tetrafluoropyridyl) compounds

The reaction of a C2-symmetric diiodo compound, 1,4-dideoxy-1,4-diiodo-2,3,-O-isopropyliden-L-threitole, with [K([18]crown-6)]P(CN)2 led to the generation of a corresponding bidentate dicyanophosphorus derivative. The in situ reaction with excess methanol and phenol yielded the corresponding bidentate dimethyl- and diphenylphosphonites, respectively. The isolated liquids were characterized by multinuclear NMR spectroscopy, elemental analysis, and mass spectrometry. The bidentate diphenylphosphonite ligand (a diphenoxyphosphane derivative) represents one of the very few functional bidentate phosphane derivatives: a DIOP [(2,2-dimethyl-1,3-dioxolane-4,5-diyl)bis(methylene)]bis(diphenylphosphane) modification, in which the phenyl groups at the phosphorus atoms are replaced by functional phenoxy groups. Treatment of the bidentate diphenylphosphonite derivative with C6F5MgBr and p-C5NF4MgBr allowed the isolation and full characterization of the comparable bidentate bis(pentafluorophenyl) and bis(p-tetrafluoropyridyl)phosphanes. The ligand properties of the novel bidentate ligand systems were evaluated through the synthesis and vibrational investigation of their tetracarbonyl-molybdenum and cyclopentadienyl-iron complexes. The pi acidity of the synthesized ligands increases in the order methoxy-相似文献   

Synthesis of Unsymmetrically Substituted Phosphane Oxides (R1R2P(O)H) and Phosphinous Acids (R1R2POH)

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

Oxidative addition of substituted arsines and stibines with bis(trifluoromethyl)nitroxyl

Reactions of bis(trifluoromethyl)nitroxyl with a number of methyl- and trifluoromethyl- substituted arsines and stibines at room temperature lead to the formation of pentavalent arsenic and antimony derivatives, namely (CH₃)_3?n(CF₃)_nM[ON(CF₃)₂]₂ (M = As, n = 0, 1, 2; M = Sb, n = 0, 1). The derivatives yield bis(trifluoromethyl)- hydroxylamine and the corresponding dichlorides on treatment with hydrogen chloride. A free radical mechanism is proposed for the oxidative addition reactions.     

Stable and Storable N(CF3)2 Transfer Reagents

Fluorinated groups are essential for drug design, agrochemicals, and materials science. The bis(trifluoromethyl)amino group is an example of a stable group that has a high potential. While the number of molecules containing perfluoroalkyl, perfluoroalkoxy, and other fluorinated groups is steadily increasing, examples with the N(CF₃)₂ group are rare. One reason is that transfer reagents are scarce and metal-based storable reagents are unknown. Herein, a set of Cu^I and Ag^I bis(trifluoromethyl)amido complexes stabilized by N- and P-donor ligands with unprecedented stability are presented. The complexes are stable solids that can even be manipulated in air for a short time. They are bis(trifluoromethyl)amination reagents as shown by nucleophilic substitution and Sandmeyer reactions. In addition to a series of benzylbis(trifluoromethyl)amines, 2-bis(trifluoromethyl)amino acetate was obtained, which, upon hydrolysis, gives the fluorinated amino acid N,N-bis(trifluoromethyl)glycine.     

Bis(trifluoromethyl)dicarbonate, CF3OC(O)OC(O)OCF3

The synthesis of the new compound, bis(trifluoromethyl)dicarbonate, CF₃OC(O)OC(O)OCF₃, is carried out by reduction of bis(trifluoromethyl)trioxidicarbonate with excess of CO at 0 °C. The product is characterized by IR, Raman, ¹³C and ¹⁹F NMR spectroscopy and its properties are compared with those of the other members of the series CF₃OC(O)O_xC(O)OCF₃, x = 0-3. Single crystals are grown at −25 °C and the X-ray diffraction analysis shows the packing of syn-syn rotamers exhibiting C₂ symmetry. DFT calculations predict this rotamer as the most stable one and also structural and vibrational data are predicted reasonably well.     

Synthesis of the first chiral bidendate bis(trifluoromethyl)phosphane ligand through stabilization of the bis(trifluoromethyl)phosphanide anion in the presence of acetone

Lewis acid/Lewis base adduct formation of the P(CF3)2- ion and acetone leads to a reduced negative hyperconjugation and, therefore, limits the C--F bond activation. The resulting increased thermal stability of the P(CF3)2- ion in the presence of acetone allows selective substitutions and enables the synthesis of the first example of a chiral, bidentate bis(trifluoromethyl)phosphane ligand: a DIOP derivative, [(2,2-dimethyl-1,3-dioxolane-4,5-diyl)bis(methylene)]bis(diphenylphosphane), in which the phenyl groups at the phosphorus atoms are replaced by strong electron-withdrawing trifluoromethyl groups. The resulting high electron-acceptor strength of the synthesized bidentate (CF3)2P ligand is demonstrated by a structural and vibrational study of the corresponding tetracarbonyl-molybdenum complex. The stabilization of the P(CF3)2- ion in the presence of acetone is based on the formation of a dynamic Lewis acid/Lewis base couple, (CF3)2PC(CH3)2O-. Although there is no spectroscopic evidence for the formation of the formulated alcoholate ion, the intermediate formation of (CF3)2PC(CH3)2O- could be proved through the reaction with (CF3)2PP(CF3)2, which yields the novel phosphane-phosphinite ligand (CF3)2PC(CH3)2OP(CF3)2. This ligand readily forms square-planar Pt(II) complexes upon treatment with solid PtCl2.     

Reactions of Trifluoronitrosomethane with bistrifluoromethylphosphorus compounds, (CF3)2PX (where x = H,Cl, CF3)

Trifluoronitrosomethane reacts with bis(trifluoromethyl)phosphine to give (CF₃)₂P(O)N(OH)CF₃ and a small amount of (CF₃)₂NOH. On the other hand, the reactions with tris(trifluoromethyl)phosphine and bis(trifluoromethyl)chlorophosphine afford (CF₃)₂NOP(O)CF₃N(CF₃)₂ and (CF₃)₂NP(O)(CF₃)Cl respectively. Isomerisation of

may be involved as found for the isomerisation of the phosphine, (CF₃)₂NOP(CF₃)₂, to the phosphoryl compound, (CF₃)₂NP(O)(CF₃)₂. Mechanisms for the above reactions are discussed.     

Endohedral gadolinium-containing metallofullerenes in the trifluoromethylation reaction

An efficient method for the synthesis of trifluoromethyl derivatives of endohedral gadolinium-containing metallofullerenes was proposed. High-purity (98–99%) trifluoromethyl derivatives Gd@C₈₂(CF₃)₅ (two isomers) and Gd₂@C₈₀(CF₃) have been synthesized for the first time. They were isolated and characterized by HPLC, MALDI-TOF mass spectrometry, and UV-Vis spectroscopy. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1457–1462, July, 2008.     

Anodic oxidation of organometallic sandwich complexes using [Al(OC(CF3)3)4] or [AsF6] as the supporting electrolyte anion

Anodic voltammetry and electrolysis of the metallocenes ferrocene, ruthenocene, and nickelocene have been studied in dichloromethane containing two different fluorine-containing anions in the supporting electrolyte. The perfluoroalkoxyaluminate anion [Al(OC(CF₃)₃)₄]⁻ has very low nucleophilicity, as shown by its inertness towards the strong electrophile [RuCp₂]⁺ and by computation of its electrostatic potential in comparison to other frequently used electrolyte anions. The low ion-pairing ability of this anion was shown by the large spread in E_1/2 potentials (ΔE_1/2 = 769 mV) for the two one-electron oxidations of bis(fulvalene)dinickel. The hexafluoroarsenate anion [AsF₆]⁻, on the other hand, reacts rapidly with the ruthenocenium ion and is much more strongly ion-pairing towards oxidized bis(fulvalene)dinickel (ΔE_1/2 = 492 mV). In terms of applications of these two anions to the anodic oxidation of organometallic sandwich complexes, the behavior of [Al(OC(CF₃)₃)₄]⁻ is similar to that of other weakly-coordinating anions such as [B(C₆F₅)₄]⁻, whereas that of [AsF₆]⁻ is similar to the more traditional electrolyte anions such as [PF₆]⁻ and [BF₄]⁻. Additionally, the synthesis and crystal structure of [Cp₂Fe][Al(OC(CF₃)₃)₄] are reported.     

Synthesis,spectroscopy and electrochemical properties of highly soluble fluoro containing phthalocyanines

2(3),9(10),16(17),23(24)-Tetrakis-4′-[3,5-bis-(trifluoromethyl)-phenoxy]-phthalocyanines, {M[Pc-β(OBz-(CF₃)₂)₄]}, (M = Zn(II), Cu(II), Co(II) and Ni(II)) were synthesized and characterized by elemental analysis, FTIR, ¹H NMR, UV–Vis and MS (Maldi-TOF) spectral data. It is shown that the 4-(3,5-bis(trifluoromethyl)-phenoxy) moieties on the periphery affect the solubility, spectroscopic data and electrochemistry of the tetrakis metallophthalocyanines. The cyclic voltammetry and differential pulsed voltammetry of the complexes give well-defined redox couples in harmony with common metallophthalocyanine complexes. Electrochemical studies show that the complexes exhibit stable monoanionic M{Pc-β-[(OBz-(CF₃)₂)₄]}¹⁻, dianionic M{Pc-β-[(OBz-(CF₃)₂)₄]}²⁻ and monocationic M{Pc-β-[(OBz-(CF₃)₂)₄]}¹⁺ species during the reduction and oxidation processes. When compared with the unsubstituted analogues, the redox potentials of the complexes shifted to more positive potentials due to the electron-withdrawing fluorine groups.     

Silver tetrakis(hexafluoroisopropoxy)aluminate as hexafluoroisopropyl transfer reagent for the chlorine/hexafluoroisopropyl exchange in imino phosphanes

Treating 1,3-dichloro-2,4-bis[tris(trimethylsilyl)silyl]-cyclo-diphosphadiazane, [HypNPCl]₂ ((Me₃Si)₃Si = Hyp), or N-(2,4,6-tri-tert-butylphenyl)imino(chloro)phosphane, Mes^∗-NP-Cl (Mes^∗ = 2,4,6-tri-tert-butylphenyl), with Ag[Al(OCH(CF₃)₂)₄] leads to the abstraction of [OCH(CF₃)₂]⁻ from the counter ion [Al(OCH(CF₃)₂)₄]⁻ in a formal Lewis acid/Lewis base reaction. The final products Hyp₂N₂P₂(Cl)(OCH(CF₃)₂), Mes^∗-NP-OCH(CF₃)₂ and the dimeric Lewis acid [Al(OCH(CF₃)₂)₃]₂ have been characterized by means of X-ray analysis.     

Chiral and Nonchiral [OsX2(diphosphane)(diamine)] (X: Cl,OCH2CF3) Complexes for Fast Hydrogenation of Carbonyl Compounds

The osmium complexes trans‐[OsCl₂(dppf)(diamine)] (dppf: 1,1′‐bis(diphenylphosphino)ferrocene; diamine: ethylenediamine in 3 , propylenediamine in 4 ) were prepared by the reaction of [OsCl₂(PPh₃)₃] ( 1 ) with the ferrocenyl diphosphane, dppf and the corresponding diamine in dichloromethane. The reaction of derivative 3 with NaOCH₂CF₃ in toluene afforded the alkoxide cis‐[Os(OCH₂CF₃)₂(dppf)(ethylenediamine)] ( 5 ). The novel precursor [Os₂Cl₄(P(m‐tolyl)₃)₅] ( 2 ) allows the synthesis of the chiral complexes trans‐[OsCl₂(diphosphane)(1,2‐diamine)] ( 6 – 9 ; diphosphane: (R)‐[6,6′‐dimethoxy(1,1′‐biphenyl)‐2,2′‐diyl]bis[1,1‐bis(3,5‐dimethylphenyl)phosphane] (xylMeObiphep) or (R)‐(1,1′‐binaphthalene)‐2,2′‐diylbis[1,1‐bis(3,5‐dimethylphenyl)phosphane] (xylbinap); diamine=(R,R)‐1,2‐diphenylethylenediamine (dpen) or (R,R)‐1,2‐diaminocyclohexane (dach)), obtained by the treatment of 2 with the diphosphane and the 1,2‐diamine in toluene at reflux temperature. Compounds 3 – 5 in ethanol and in the presence of NaOEt catalyze the reduction of methyl aryl, dialkyl, and diaryl ketones and aldehydes with H₂ at low pressure (5 atm), with substrate/catalyst (S/C) ratios of 10 000–200 000 and achieving turnover frequencies (TOFs) of up to 3.0×10⁵ h^?1 at 70 °C. By employment of the chiral compounds 6 – 9 , different ketones, including alkyl aryl, bulky tert‐butyl, and cyclic ketones, have successfully been hydrogenated with enantioselectivities up to 99 % and with S/C ratios of 5000–100 000 and TOFs of up to 4.1×10⁴ h^?1 at 60 °C.     

Stable phosphinous acids

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 (C_s symmetry) is favored at the same level of theory by about ΔE_ZP = 14 kJ/mol compared with the phosphane oxide structure (C_s symmetry).     

Preparation and Structure of [Me3N(CF3)2BCCB(CF3)2NMe3]

Bis‐trimethylamine‐ethynyl‐di‐bis(trifluoromethyl)borane [Me₃N(CF₃)₂BCCB(CF₃)₂NMe₃] ( 1 ) has been prepared from trimethylamine‐ethynyl‐bis(trifluoromethyl)borane, [HCCB(CF₃)₂NMe₃], and dimethylamino‐bis(trifluoromethyl)borane, (CF₃)₂BNMe₂. The structure of 1 has been determined by x‐ray crystallography. In the solid state the molecule possesses crystallographic C_i symmetry. The acetylenic attachment to the boron atom is characterized by a short B–C bond length of 1.565(4) Å and an essentially linear B–C–C′ bond angle of 178.1(4)°.     

Synthesis of Aryl-Manganese(III) Fluoride Complexes via α-Fluorine Elimination from CF3 and Difluorocarbene Generation

We report the synthesis of cyclometalated monoaryl Mn^III fluoro complexes using bis(trifluoromethyl)zinc reagent, Zn(CF₃)₂(DMPU)₂, under mild conditions via a reaction pathway that involves initial transmetalation followed by α-fluorine elimination. The formation of difluorocarbene in these reactions was detected by trapping experiments. Such facile difluorocarbene generation from Mn^III results in moderate enhancement of difluoropropanation and difluoropropenation of alkenes and alkynes using Zn(CF₃)₂(DMPU)₂ at lower temperature (20–60 °C) and short reaction time, suggesting potential application of manganese(III) perfluoroalkyl complexes as reactive species for carbene transfer reactivity.     

Iodomethane oxidative addition to β-diketonatobis(triphenylphosphite)rhodium(I) complexes: A synthetic, kinetic and computational study

New rhodium(I)- and rhodium(III)-β-diketonato complexes of the type [Rh(FcCOCHCOR)(P(OPh)₃)₂] and [Rh(FcCOCHCOR)(P(OPh)₃)₂(CH₃)(I)], with Fc = ferrocenyl and R = Fc, CH₃ and CF₃, have been synthesized. The reactivity of complexes of the type [Rh(β-diketonato)(P(OPh)₃)₂] increase in the order: β-diketonato = (CF₃COCHCOCF₃)⁻ < (CF₃COCHCOPh)⁻ < (CF₃COCHCOCH₃)⁻ < (PhCOCHCOPh)⁻ < (CF₃COCHCOFc)⁻ < (CH₃COCHCOPh)⁻ < (CH₃COCHCOCH₃)⁻ < (CH₃COCHCOFc)⁻ < (FcCOCHCOFc)⁻, giving linear relationships between the kinetic parameter ln k₂ and the parameters that are related to the electron density on the rhodium centre; the sum of the group electronegativities of the β-diketonato side groups (χ_R + χ_R′) and the pK_a of the uncoordinated β-diketone RCOCH₂COR′. The large negative values of the volume and entropy of activation indicated a mechanism which occurs via a polar transition state. A density functional theory study, at the PW91/TZP level of theory, indicates that oxidative addition of iodo methane to [Rh(FcCOCHCOCF₃)(P(OCH₃)₃)₂] occurs via a two-step mechanism. This mechanism involves a nucleophilic attack by the metal on the methyl carbon to displace iodide to form a metal-carbon bond and the coordination of iodide to the five-coordinated intermediate to give a six-coordinated trans alkyl product.