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The organic salt {beta}''-(BEDT-TTF){sub 2}SF{sub 5}CH{sub 2}CF{sub 2}SO{sub 3} is a two-dimensional metal with a quarter-filled conduction band. In the metallic state the optical conductivity evidences interaction of the charge carriers with charge-order fluctuations that become stronger as temperature decreases. In the superconducting phase below T{sub c} {approx} 5K, indications of the superconducting gap with 2{Delta} {approx} 12 cm{sup -1} are observed in the optical spectrum, corresponding to 2{Delta}/k{sub B}T{sub c} {approx} 3.3. Its temperature and magnetic field dependences are also consistent with predictions by the BCS theory of a weakly coupled superconductor. The conductivity ratio {sigma}{sub 1}(T = 1.75 K)/{sigma}{sub 1}(10 K) indicates the opening of the superconducting gap in {beta}''-(BEDT-TTF){sub 2}SF{sub 5}CH{sub 2}CF{sub 2}SO{sub 3}.

1,4-Disubstituted 1,2,3-triazoles containing a pentafluorosulfanylalkyl group were synthesized in good to excellent yields (57–91%) by the click cycloadditions of in situ generated SF 5 -alkyl azides with aromatic and aliphatic alkynes. Nucleophilic substitution of the SF 5 group was observed for the first time in a bench-top reaction.

N-C bonded (non-bridged) 5-(1,2,3-triazol-1-yl)tetrazoles were synthesized by the Cu(I)-catalyzed 1,3-dipolar azide-alkyne cycloaddition click reaction using 5-azido-N-(propan-2-ylidene)-1H-tetrazole (1). For example, the click reaction of 1 in the presence of CuSO(4)5 H(2)O and Na ascorbate at 65-70 degrees C for 48 h in CH(3)CN/H(2)O co-solvent was found to be limited to only terminal alkynes that have electron-withdrawing groups, CF(3)C[triple chemical bond]CH (2 a) and SF(5)C[triple chemical bond]CH (2 b), giving rise to isopropylidene-[5-(4-trifluoromethyl-1,2,3-triazol-1-yl)tetrazol-1-yl]amine (3 a) and isopropylidene-[5-(4-pentafluorosulfanyl-1,2,3-triazol-1-yl)tetrazol-1-yl]amine (3 b) in 47 % and 66 % yields, respectively. When carried out under conditions using CuI and 2,6-lutidine as catalysts at 0 degrees C for 13 h in CHCl(3), the click reaction was versatile toward alkynes even those having electron-donating groups. Properties of new products were determined and compared with those of 1. Heats of formation, detonation pressures, detonation velocities and impact sensitivities are reported for these new 5-(1,2,3-triazol-1-yl)tetrazoles.

A stable and storable precursor of 2-SF 5 -butadiene, 3-SF 5 -3-sulfolene, has been synthesized and its reactivity studied with several olefinic compounds. When SF 5 Br is added to sulfolene, 3-bromo-4-SF 5 -sulfolane is formed and when reacted further with silver tosylate forms 4-SF 5 -2-sulfolene. The 4-SF 5 -2-sulfolene undergoes rearrangement with silicic acid to give 3-SF 5 -3-sulfolene and when heated forms 2-SF 5 -butadiene; in the absence of a dienophile, dimerization does occur. The new 2-SF 5 -butadiene is a reactive diene undergoing a Diels–Alder reaction with olefinic sytems such as maleic anhydride, p -naphthoquinone, and methyl acrylate.

New quaternary salts of pentafluorosulfanyl-substituted (SF5) N-methylimidazole (1), 4-amino-1,2,4-triazole (3) or pyridine (5) were prepared and characterized. Most of the salts exhibit good thermal stabilities and low melting points placing them in the ionic liquid class. Their densities range between 1.4 and 1.8 g/cm3. The standard enthalpies of formation for the new salts were calculated by the use of computationally feasible DFT(B3LYP) and MP2 methods in conjunction with an empirical approach based on densities of salts. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

Novel liquid crystals based on fluorinated carbon chains and terminated with SF5 groups are presented for the first time. Attachment of an SF5 group separated from a benzylidine group by a fluorinated spacer leads to monotropic nematic and smectic phases, while an enantiotropic nematic phase is observed in mixtures. The phase sequence of these new compounds is comparable to hydrocarbon analogues of nO.m (n-alkoxy-m-alkylbenzylidine) series. Despite a long alkoxy chain, the nematic → smectic A transition is closer to second order, with ≈ 0.995 values that are even higher than for the nCB (n-alkylcyanobiphenyls) series. Single crystal and quantum computational studies suggest that electrostatic interactions play a major role in governing the value of MTCP. Molecular packing in the crystal structure exhibits monoclinic P21/a symmetry. A flexible synthetic strategy that allows the synthesis of another homologous series with a bend in the molecular structure is also presented. The bent core structure of 10O.2 ...

The structure of SF(5)OSO(2)F has been investigated using gas-phase electron diffraction and quantum-chemical calculations. It is found to exist primarily in the gauche form (SF(5) group gauche relative to the S-F bond of the SO(2)F group with phi(S-O-S-F = 71(7) degrees ). A small contribution of the trans conformer cannot be excluded. Photoelectron spectroscopy gives ionization energies for the sulfur 2p electrons that reflect the relative electronegativities of fluorine and oxygen. The widths of the peaks in the photoelectron spectra indicate that there is considerable vibrational excitation associated with the core ionization of the sulfur atoms.

Measurements of the London penetration depth, λ(T), are reported for crystals of superconducting κ-(ET) 2 Cu[N(CN),]Br (T C = 11.6 K) and β-(ET) 2 -SF 5 CH 2 CF 2 SO 3 (T C = 5.2 K) at temperatures down to 0.35 K. For K-(ET)2 Cu[N(CN)2]Br the superfluid density shows the power law behavior characteristic of nodal quasiparticles with impurity scattering. The rate of change of superfluid density with temperature is higher than predicted by a weak-coupling d-wave model and higher than observed in the copper oxides. The in-plane penetration depth consistently shows a T 3/2 dependence while the interplane penetration depth varies as T 1.22 . Measurements in β-(ET) 2 -SF 5 CH 2 CF 2 SO 3 also show power law behavior consistent with nodal quasiparticles but with greater impurity scattering than in κ-(FT) 2 Cu[N(CN) 2 ]Br.

A series of reactions between SF5CF2CF2I and SF5(CF2)4I with F2CCF2 was carried out in an effort to find the most effective methods for chain-extension. Also, for the first time, SF5(CF2)8I and SF5(CF2)10I have been prepared and isolated. The reaction conditions for the addition of H2CCH2 were also investigated. A determination of the crystal structure of the SF5(CF2)4CH2CH2I has been carried out: the crystal system is monoclinic, with space group P2(1)/n and a=23.465(5) A; b=6.0971(12) A; c=44.892(9) A; α=90°; β=99.38(3)°; γ=90°; Z=20.

The first quaternary salts of pyridine (2), N-methyl imidazole (3), N-propyl triazole (4), and pyridazine (5) that contain the pentafluorosulfanyl (SF(5)) group were prepared and characterized. Neat reactions of the aromatic nitrogen compounds with SF(5)(CF(2))(n)(CH(2))(m)I (n = 2 or 4, m = 2 or 4) gave quaternary iodides 6a-c, 7a-c, 8a, and 9a,b, which were metathesized with LiN(SO(2)CF(3))(2) to form the bis(trifluoromethylsulfonyl)amides 10a-c, 11a-c, 12a, and 13a,b, in high yields. With the exception of the pyridine bis(trifluoromethylsulfonyl)amide salts, the compounds melted or exhibited a T(g) at

Three 2 : 1 salts of the organic donor molecule bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF or ET) with trifluoromethylsulfonyl-based anions N(SO2CF3)2−, CH(SO2CF3)2− and C(SO2CF3)3− were prepared by electrocrystallization. These salts were characterized by single-crystal X-ray diffraction, electron spin resonance (ESR) spectroscopy, electrical resistivity measurements and electronic band structure calculations. (ET)2N(SO2CF3)2 is a two-dimensional (2D) metal, but its ESR spin susceptibility above 150 K shows a weakly semiconducting behavior, presumably because during ESR measurements the sample cooling rate is slow hence allowing the disordered anions to readjust their positions. (ET)2CH (SO2CF3)2 is a 2D metal and undergoes a metal-to-insulator (MI) transition at 110 K due probably to a geometry change of the donor molecule layers. (ET)2C(SO2CF3)3 is a one-dimensional (1D) metal and undergoes an MI between 180 and 240 K, which is expected to be of charge density wave type.

A new perfluorinated acrylate monomer containing the SF 5 (CF 2 ) 6 -perfluorinated side chain was synthesized and polymerized into films. Bulk monomer characterization is consistent with the molecular structure based on FTIR, mass spectrometry and NMR analyses. The surface properties of polymer coatings were studied with aqueous wetting (contact angle) and X-ray photoelectron spectroscopy (XPS) methods. The surface composition is shown to be highly enriched in the terminal side chain SF 5 -chemistry and exhibits properties consistent with a highly apolar, non-wetting perfluorinated polymer surface. Depth-dependent XPS studies using angular-resolved methods (ADXPS) confirmed a non-stoichiometric enrichment of sulfur and fluorine at the film ambient interface, consistent with a surface presence of the terminal SF 5 -group and possibly film structural anisotropy in the surface zone. Time-of-flight (TOF) secondary ion mass spectrometry (SIMS) analysis supplements the XPS data by showing the presence of all expected SF 5 -acrylate chemistry components in the outer 15 A of the film surface.

Discrete, organic anions provide an attractive alternative for the synthesis of molecular superconductors. We have previously prepared the first completely organic superconductor, β″-(BEDT-TTF) 2 SF 5 CH 2 CF 2 SO 3 [BEDT-TTF, hereafter abbreviated ET, is bis(ethylenedithio)tetrathiofulvalene]. Molecular metals which contain organic anions are essentially free of the magnetic impurities (i.e. Cu +2 ) that often plague the physical property studies of organic superconductors such as κ-(ET) 2 Cu[N(CN) 2 ]Br. We have undertaken a research effort aimed at the crystallization of conducting charge transfer salts which possess fluorinated alkylsulfonate anions as the charge compensating entities. Herein we report the extension of this work to include the synthesis and characterization of ET salts of the trifluoromethylsulfonate anions, CF 3 CRR′SO 3 − (R, R′=F, H).

Excluding enantiomers, there are 14 possible rotomeric conformations of 4-fluorobutan-1-ol, of which two are capable of forming an internal O−H···F hydrogen bond. The composition of the gaseous system is of special interest because it is determined by the energies of the conformers which reflect the energies of the hydrogen bonds. We have investigated the conformational composition of the gaseous system and the molecular structures of the conformers at 83 °C by gas-phase electron diffraction (GED) augmented by molecular orbital calculations. Because of the complexity of the 4-fluorobutan-1-ol system, the parameters of the several models tested were simplified by various constraints taken from the theoretical work. With these constraints, the best agreement with the GED data was obtained with a model consisting of about equal amounts of hydrogen-bonded and non-hydrogen-bonded conformers. Because the curled-up shape of the two forms capable, in principle, of forming internal hydrogen bonds is expected to be...

The reaction of pentafluoro-λ 6 -sulfanyl(SF 5 )-perfluoroalkyl iodides with benzene is a convenient route for preparing SF 5 -perfluoroalkyl benzene derivatives, SF 5 (CF 2 ) n C 6 H 5 ( n =2, 4, 6, 8), a new class of perfluoroalkylaromatic compounds. The preparation and characterization of these new materials are described.

The structure and conformational composition of peroxydisulfuryl difluoride, S2O6F2, have been investigated by gas-phase electron diffraction. Some of the results from ab initio molecular orbital calculations (MP2/6-311+G∗) were used as constraints in the analysis. There is both experimental and theoretical evidence that only conformers with a gauche X–O–O–X torsion angle are present in the gaseous sample. Of these, only two conformers of symmetry C2 (G+G+and G−G−) and one of symmetry C1 (G+G−), where G± designates positive/negative rotation around the O–S bonds at either end of the molecule) were found to be plausible components of the gaseous mixture. In experiments at 298 K, about equally good fits were found with two models, model A consisting of a ratio of G−G−/G+G+ equal to 57/43 (2σ=27), and model B consisting of a ratio of G−G−/G+G− equal to 38/62 (2σ=14). The composition of model A corresponds to Δ G 0 =G 0 ( G + G + )−G 0 ( G − G − )=0.17 (σ=0.24) kcal/mol, and that of model B to Δ G 0 =G 0 ( G + G − )−G°( G − G − )=−0.29 (σ=0.12). A system composed of only C2 symmetry conformers, such as model A, is favored by IR and Raman data, but our electron-diffraction results do not allow a choice. However, the bond lengths and bond angles for all conformers are similar so that, except for the torsion angles, the parameter values for the G−G− form are also reasonably close to those in the other forms. These distances (rg (A)) and angles (∠α (°)) values with 2σ uncertainties are r(S O)=1.406(2) A, r(S–F)=1.539(3) A, r(O–S)=1.620(4) A, r(O–O)=1.453(14) A, 〈∠(O–S O)〉=1/2[(O–S O4)+∠(O–S O5)]=107.2(12)°, Δ∠(O–S O)=∠(O–S O4)−∠(O–S O5)=8.1° (assumed), ∠(O–S–F)=98.2(18)°, ∠(O–O–S)=108.6(10)°, ∠(O S O)=126.7(15)°, and ∠(S–O–O–S)=122.7(56)°.

Deuterium substitution of the ethylene end groups of the ET [ET: BEDT-TTF or bis(ethylenedithio)tetrathiafulvalene] electron-donor molecule results in a 0.25 K increase in the superconducting transition temperature of three molecular superconductors derived from this molecule. Simplistically speaking, this change in T c is in contradiction to that predicted by the electron–phonon coupling mechanism of the BCS theory. We suggest that the slight shortening of the C–D bond relative to the C–H bond, coupled with the recent findings of a large, negative uniaxial pressure derivative of T c in κ-(ET) 2 Cu(SCN) 2 and β ′′ -(ET) 2 SF 5 CH 2 CF 2 SO 3 , can explain this unique effect. Herein we report the first study of the effect of deuterium substitution on the superconducting transition temperature in a molecular-based superconductor in which the electron-donor molecules are packed in a β ′′ motif, viz., β ′′ -(ET) 2 SF 5 CH 2 CF 2 SO 3 . This compound is ideally suited for this study because it contains discrete (non-polymeric) anions, has a completely ordered structure, is indefinitely stable in air at room temperature, and is free from possible magnetic impurities. Substitution of the eight hydrogen atoms of the ET molecule by deuterium causes the T c of β ′′ -(ET) 2 SF 5 CH 2 CF 2 SO 3 to increase from 4.34±0.05 to 4.61±0.03 K. These values were determined by measuring several representative crystals from various parallel electrocrystallization experiments containing h 8 - or d 8 -ET that was prepared in parallel syntheses. This is the first example which demonstrates that the inverse (positive) isotope effect previously observed in κ-phase salts is also present in a β ′′ -phase superconductor.

The first purely organic BEDT-TTF spin−Peierls system, β‘-(ET)2SF5CF2SO3, has been confirmed using a high-frequency electron paramagnetic resonance (EPR) cavity perturbation technique. The material exhibits the characteristics of a quasi-one-dimensional (1D) Heisenberg antiferromagnetic spin system above 30 K, but undergoes a second-order transition, at TSP = 33 K, to a singlet ground state, due to a progressive spin−lattice dimerization. The spin−Peierls state is evidenced by a sharp drop in the spin susceptibility below 24 K for the magnetic field (of order 2.5 T) parallel to each of the three principal axes (i.e., H ∥a, H∥b, and H∥c). The spin−Peierls distortion based on g value shift analysis appears to be predominately along the crystallographic b axis. The singlet−triplet gap, Δσ(0) = 114 (±21) K, was determined using a modified BCS theory. Also, we describe in some detail the millimeter-wave vector network analyzer (MVNA) for researchers who have interest in precision EPR measurements at magnetic f...

A new organic conductor, β″-(BEDT-TTF)2SF5CHFCF2SO3 [BEDT-TTF, hereafter abbreviated ET, refers to bis(ethylenedithio)tetrathiafulvalene], was prepared by electrocrystallization. The crystal structure of this salt was determined by single crystal X-ray diffraction at 298 and 150 K, its physical properties were examined by electrical resistivity, Raman spectroscopy and EPR measurements, and its electronic structure was calculated and compared with that of the analogous salt β″-(ET)2SF5CH2CF2SO3. Whereas β″-(ET)2SF5CHFCF2SO3 has disordered anions and undergoes a metal-to-insulator transition at ∼190 K, β″-(ET)2SF5CH2CF2SO3 has ordered anions and is semiconducting down to ∼100 K, metallic below ∼100 K, and superconducting below 5 K. At room temperature both β″-(ET)2SF5CHFCF2SO3 and β″-(ET)2SF5CH2CF2SO3 have similar electronic band structures and physical properties. When the temperature is lowered, each donor molecule stack becomes dimerized in both salts. However, the interdimer interaction within each donor stack nearly vanishes in β″-(ET)2SF5CHFCF2SO3, but remains substantial in β″-(ET)2SF5CH2CF2SO3.

The authors report on Shubnikov-de Haas (SdH) and de Haas-van Alphen (dHvA) results for the highly two-dimensional (2D) organic superconductors {kappa}-(ET){sub 2}I{sub 3} ({Tc} = 3.5 K) and {beta}{double_prime}-(ET){sub 2}SF{sub 5}CH{sub 2}CF{sub 2}SO{sub 3} ({Tc} = 4.4 K). The SdH oscillations of both materials show an apparent deviation from the well-understood 2D dHvA signal at low temperatures and high magnetic fields. For {kappa}-(ET){sub 2}I{sub 3}, the mechanism leading to this behavior still needs to be clarified. For {beta}{double_prime}-(ET){sub 2}SF{sub 5}CH{sub 2}CF{sub 2}SO{sub 3}, an anomalous steady background part of the magnetoresistance seems to account for the observed discrepancies.

A new SF 5 -terminated perfluoroalkyl thiol — SF 5 (CF 2 ) 6 CH 2 CH 2 SH — and a symmetric SF 5 -terminated dialkyl disulfide — [SF 5 CH–CH(CH 2 ) 8 S] 2 — were synthesized from the corresponding SF 5 -terminated precursors. The chemistry employed in the preparation of the disulfide encompasses high yield pathways for the preparation of new SF 5 -long chain derivatives.

We report on resistance noise spectroscopy measurements in the superconducting state of two quasi-two-dimensional organic superconductors. The superconducting state of β ″ ‐ ( ET ) 2 SF 5 CH 2 CF 2 SO 3 is homogeneous, whereas κ ‐ ( ET ) 2 Cu [ N ( CN ) 2 ] Cl under pressure is located in the inhomogeneous region of the phase diagram, where antiferromanetic/insulating and superconducting phases coexist. For the latter material, the finite noise level even well below T c is understood in the framework of a random resistor network. Furthermore, the noise provides evidence for percolation-type superconductivity. For homogeneous β ″ ‐ ( ET ) 2 SF 5 CH 2 CF 2 SO 3 , however, no indications of percolation effects are found: the noise in the superconducting state vanishes and the normalized noise level S R / R 2 is generally one order of magnitude lower.

We report the observation of Shubnikov--de Haas (SdH) oscillations in the mixed state of the organic superconductor {beta}''-(BEDT-TTF){sub 2}SF{sub 5}CH{sub 2}CF{sub 2}SO{sub 3} (T{sub c}{approx}4.4K). At low temperatures the SdH oscillations persist clearly below the upper critical field B{sub c2}(0){approx}3.6T almost down to the field where the resistivity vanishes. Rather unusually, no additional damping of the SdH-signal amplitude -- as well as of the de Haas--van Alphen amplitude -- is observed in the superconducting state. This indicates that the damping in the vortex state of this quasi-two-dimensional superconductor is different in character to that observed for most three-dimensional materials.

Two new SF5-terminated perfluoroalkylsilanesSF5(CF2CF2)nCH2CH2SiCl3 (n = 1 and 2)were synthesized by addition of trichlorosilane to the corresponding synthetic SF5-terminated perfluoroalkenes by hydrosilylation. Thin films of these SF5-silanes on clean silicon oxide substrates were characterized by ellipsometry, aqueous contact angle, and X-ray photoelectron spectroscopy (XPS) methods. The shorter SF5-silane film shows a hydrophobic interface with minimal angle dependence in depth-dependent XPS analysis, suggesting a poorly organized film. The longer SF5-silane exhibits a high aqueous static contact angle (106°) and angular-dependent XPS compositional variance consistent with improved film assembly (fewer defects and more vertical chain orientation). Bulk SF5-bearing materials were fabricated by silane hydrolysis, producing SF5-polymers and cross-linked networks bearing the unique SF5 perfluoroalkyl chemistry.

We report high-resolution measurements of the coefficient of thermal expansion, $\ensuremath{\alpha}{=l}^{\ensuremath{-}1}\ifmmode\times\else\texttimes\fi{}(\ensuremath{\partial}l/\ensuremath{\partial}T),$ on single crystals of the organic superconductors ${\ensuremath{\beta}}^{\ensuremath{''}}\ensuremath{-}{(\mathrm{ET})}_{2}{\mathrm{SF}}_{5}{\mathrm{CH}}_{2}{\mathrm{CF}}_{2}{\mathrm{SO}}_{3}$ and $\ensuremath{\kappa}\ensuremath{-}{(\mathrm{ET})}_{2}\mathrm{Cu}(\mathrm{NCS}{)}_{2}.$ For both salts we find large and highly anisotropic phase-transition anomalies at ${T}_{c}.$ Combining these data with literature results on the specific heat via the Ehrenfest relation, the uniaxial pressure coefficients of ${T}_{c}$ can be determined. Most remarkably, a strikingly similar in-plane vs out-of-plane anisotropy is found for both compounds: the strong suppression of ${T}_{c}$ observed in hydrostatic-pressure experiments is dominated by a huge negative uniaxial stress effect perpendicular to the conducting planes. Therefore we expect that an increase of ${T}_{c}$ in this class of superconductors can be obtained by enlarging the distance between the conducting layers. Application of magnetic fields perpendicular to the planes for the ${\ensuremath{\beta}}^{\ensuremath{''}}\ensuremath{-}{(\mathrm{ET})}_{2}{\mathrm{SF}}_{5}{\mathrm{CH}}_{2}{\mathrm{CF}}_{2}{\mathrm{SO}}_{3}$ salt were found to result in pronounced superconducting fluctuation effects and scaling behavior in $\ensuremath{\alpha}(T,B).$ Owing to the pronounced phase-transition anomalies in $\ensuremath{\alpha}(T,B)$ at ${T}_{c},$ our measurements allow for an accurate determination of the upper critical fields. We find ${B}_{{c}_{2}}^{\ensuremath{\perp}}(0)=(1.4\ifmmode\pm\else\textpm\fi{}0.2) \mathrm{T}$ and ${B}_{{c}_{2}}^{\ensuremath{\Vert}}(0)=(10.4\ifmmode\pm\else\textpm\fi{}0.5) \mathrm{T}$ for fields perpendicular and parallel to the conducting planes, respectively.

de Haas-van Alphen measurements made on the organic metal ${\ensuremath{\beta}}^{\ensuremath{''}}\ensuremath{-}(\mathrm{BEDT}\ensuremath{-}\mathrm{TTF}{)}_{2}{\mathrm{SF}}_{5}{\mathrm{CH}}_{2}{\mathrm{CF}}_{2}{\mathrm{SO}}_{3}$ reveal the existence of an ideal two-dimensional (2D) Fermi surface, but rather than having the conventional sawtooth wave form that is normally observed in all other 2D electron gases, instead, an ``inverse sawtooth'' wave form is observed, which is to be expected when the chemical potential is pinned at a constant value. While this proves the existence of the theoretically predicted quasi-one-dimensional band, it further implies that this band has an exceptionally large density of states.

Reaction of SF 5 Br with various acrylic esters, CH 2 CHCOOR, where R = C 2 H 5 /C(CH 3 ) 3 and CH 2 C(CH 3 )COOCH 3 , CH 2 C(CH 2 Cl)-COOC 2 H 5 , CH 2 C( n -C 7 H 15 )COOC 2 H 5 resulted in 1:1 adducts with the SF 5 -group attached to the CH 2 portion of the acrylic ester. These adducts were converted to halogen-free saturated esters, an alcohol [SF 5 (CH 2 ) 3 OH] an acid [SF 5 (CH 2 ) 2 COOH] and a bromide [SF 5 (CH 2 ) 3 Br]. Therefore, a method for chain-elongation of SF 5 -aliphatic hydrocarbons has been devised. With ethyl acrylate, a 2:1 adduct was also isolated. The reaction of SF 5 Cl with (C 2 H 5 O) 2 CCHCOOC 2 H 5 gave chloromalonate. The compounds were characterized by their infrared, nuclear magnetic and mass spectral data.

Salts of the donor molecule, bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF or ET), with pentafluorothiomethylsulfonate (SF{sub 5}CX{sub 2}SO{sub 3}{sup -}, X = H or F) anions have been prepared. Three phases, {beta}'-(ET){sub 2}SF{sub 5}CH{sub 2}SO{sub 3}, {beta}'-(ET){sub 2}SF{sub 5}CF{sub 2}SO{sub 3}, and {beta}'-(ET){sub 2}SF{sub 5}CHFSO{sub 3} were obtained by electrocrystallization with the corresponding LiSF{sub 5}CX{sub 2}SO{sub 3} electrolytes. The structures of these salts were determined by single-crystal X-ray diffraction, and their physical properties were examined by electrical resistivity measurements as well as by ESR and Raman spectroscopy. The {beta}'-(ET){sub 2}SF{sub 5}CH{sub 2}SO{sub 3}, {beta}'-(ET){sub 2}SF{sub 5}CHFSO{sub 3} and {beta}'-(ET){sub 2}SF{sub 5}CF{sub 2}SO{sub 3} salts are considerably different in their crystal structures, physical properties, and electronic structures despite the similarity in the structures of the SF{sub 5}CX{sub 2}SO{sub 3}{sup -} (X = H, F) anions. The {beta}'-(ET){sub 2}SF{sub 5}CH{sub 2}SO{sub 3} salt has two kinds of ET donor molecules with considerably different charge densities. The electronic structure of {beta}'-(ET){sub 2}SF{sub 5}CHFSO{sub 3} has both one-dimensional (1D) and two-dimensional (2D) Fermi surfaces which are similar to those found in the organic superconductor {beta}'-(ET){sub 2}SF{sub 5}CH{sub 2}CF{sub 2}SO{sub 3}. The ESR data for the {beta}'-(ET){sub 2}SF{sub 5}CF{sub 2}SO{sub 3} salt indicate that it opens a spin gapmore » below 45 K. The differences in the physical properties of the three salts were analyzed by calculating the HOMO-HOMO interaction energies between nearest-neighbor ET molecules in their donor molecule layers.« less

We report the polarized infrared and optical reflectance of {beta}{sup {double_prime}}-(ET){sub 2}SF{sub 5}CH{sub 2}CF{sub 2}SO{sub 3} as a function of temperature. This fully organic superconductor displays weakly metallic behavior over the entire temperature range of our investigation. The electronic properties present several unusual features including the lack of a conventional free carrier (Drude) response at low temperature, infrared localization phenomena, and an unexpected temperature dependence of the oscillator strength. Similar behavior is observed in other {beta} and {beta}{sup {double_prime}} superconductors above T{sub c}, suggesting that this class of compounds is very close to a metal {r_arrow} insulator transition where electronic correlations are important and the Drude response carries very little spectral weight. Vibronic features increase in intensity with decreasing temperature in the infrared, as expected. The temperature dependence of key anion vibrational modes are discussed in terms of intermolecular hydrogen bonding within the anion pocket. thinsp thinsp {copyright} {ital 1999} {ital The American Physical Society}

The electronic structure of the organic superconductor {beta}''-(BEDT-TTF){sub 2}SF{sub 5}CH{sub 2}CF{sub 2}SO{sub 3} (BEDT-TTF is bis(ethylenedithio)tetrathiafulvalene) was characterized with the use of electron spin resonance (ESR) spectroscopy and electronic band structure calculations. The room-temperature ESR line width is 24-27 G in the plane of a donor molecule layer (i.e., in the ab-plane) and {approx}32 G along the normal to this plane (i.e., along the c*-direction). The ab-plane anisotropy of the microwave conductivity was extracted for the first time from the ESR Dysonian line shape analysis. The in-plane conductivity varies sinusoidally, is maximal along the interstack direction (b-axis), and is minimal along the donor stack direction (a-axis). The Fermi surfaces of the title compound consist of a 2D hole pocket and a pair of 1D wavy lines. The directions for the in-plane conductivity maximum and minimum are in excellent agreement with the electronic band structure calculated for {beta}''-(BEDT-TTF){sub 2}SF{sub 5}CH{sub 2}CF{sub 2}SO{sub 3}, and the origin of the in-plane conductivity anisotropy lies in the one-dimensional part of the Fermi surface. This is the first time that an organic conductor shows Dysonian ESR line shape due to its 2D and strongly metallic nature, yet the 1D character is revealed simultaneously through themore » in-plane conductivity anisotropy.« less

Electrocrystallization of ET in the presence of aromatic and aliphatic sulfonate anions has led to many new ET salts. These new ET based sulfonate complexes are characterized with use of x-ray diffraction, four-probe conductivity measurements, ESR and Raman spectroscopies. A new κ(4 × 4) donor packing motif was observed in (ET)2(C6H5CH2SO3)(H2O). Strong hydrogen bonding between the sulfonate anion S-O and the donor ethylene C-H provides the driving force for the ET salt formation. Many of these new sulfonate salts are highly conductive with some remaining metallic to ~ 4 K.

In this paper, we report transport measurements of interlayer magnetoresistance with field parallel and perpendicular to the current direction in an all organic superconductor ${\ensuremath{\beta}}^{\ensuremath{''}}\ensuremath{-}{(\mathrm{B}\mathrm{E}\mathrm{D}\mathrm{T}\ensuremath{-}\mathrm{T}\mathrm{T}\mathrm{F})}_{2}{\mathrm{SF}}_{5}{\mathrm{CH}}_{2}{\mathrm{CF}}_{2}{\mathrm{SO}}_{3}.$ For $H\ensuremath{\parallel}I,$ the isothermal magnetoresistance $R(H)$ at low temperatures $(Tl~{T}_{c})$ displays a peak effect as a function of field. For $H\ensuremath{\perp}I,$ $R(H)$ increases monotonically with increasing field. The results are very analogous to the interlayer magnetoresistance in $\ensuremath{\kappa}\ensuremath{-}(\mathrm{B}\mathrm{E}\mathrm{D}\mathrm{T}\ensuremath{-}\mathrm{T}\mathrm{T}\mathrm{F}{)}_{2}X$ compounds. The observation of the peak effect or negative magnetoresistance in different systems for $H\ensuremath{\parallel}I\ensuremath{\perp}$ plane suggests that it is intrinsic to the layered organic superconductors. For $H\ensuremath{\perp}I,$ the large positive magnetoresistance is in a general agreement with a two band model for charge transport.

SF5Br reacts with 1,2-haloethylenes (F, Cl, Br) in distinct ways. In the case of F- and Cl-olefins, the expected addition occurs while with 1,2-dibromoethylene a metathetical reaction yielding in a clean reaction a 1:1 mixture of SF5CH CHBr and CHBr2CHBr2 is found. The mechanism for this reaction is discussed.

The synthesis of new compounds that contain both a terminal pentafluoro-λ 6 -sulfanyl (SF 5 ) group and an alkene or alcohol functional group is reported. Five new SF 5 containing alkenes and one new SF 5 containing alcohol were prepared: SF 5 CH 2 CHBrCH 2 CF CF 5 ( 1 ), SF 5 CF 2 CF 2 CH 2 CHICH 2 CF CF 2 ( 2 ), SF 5 CF 2 CF 2 CH 2 CH 2 CH 2 CF CF 2 ( 3 ), SF 5 CF 2 CF 2 CH CH 2 ( 4 ), SF 5 (CF 2 CF 2 ) 2 CH CH 2 ( 5 ) and SF 5 CF 2 CF 2 CH 2 CH 2 OH ( 6 ). These compounds are useful as monomers or as intermediates in the preparation of polymers, polymer surface coatings, and surfactants.

We briefly review some of the recent high-field de Haas–van Alphen (dHvA) results we obtained for the quasi-two-dimensional organic metals and superconductors of the type α-(ET) 2 X , where ET (=BEDT–TTF) is bis(ethylenedithio)-tetrathiafulvalene and X is a monovalent anion. We further report on new dHvA, Shubnikov–de Haas, and specific-heat results for the recently synthesized organic superconductor β″− (ET) 2 SF 5 CH 2 CF 2 SO 3 (T c =4.5 K ) . The Fermi-surface topology, the possible influence of the low dimensionality on the quantum oscillations, and the influence of many-body interactions are discussed. The results indicate the importance of electron–phonon interaction and point towards strong coupling.

The reaction of pentafluorothio(fluorosulfonyl)ketene with formaldehyde has yielded the novel solid ether [SF 5 CH(SO 2 F)CH 2 ] 2 O, 1 . The crystal structure has been determined: crystal class tetragonal I4; a = b = 11.069(2) A, c = 6.0780(1) A; α=β=γ=90°; V = 744.7(2) A 3 ; Z = 2. Hydrogen bonding (CH⋯O) is believed responsible for the solid state nature of this material.

The gas-phase structure of 4,4-difluoro-3-(pentafluorothio)-1,2-oxathietane-2,2-dioxide, SF5 CHCF 2 OS O2 (1), has been determined by gas electron diffraction; a planar structure of the four-membered sultone ring with a puckering angle of 1 ± 5° was found. This result is in contrast to a previous X-ray crystallographic study which reports a nonplanar ring conformation with a puckering angle of 14°. The comparison between the gas-phase and crystal structures demonstrates that deformation of the ring in the solid state is due to intermolecular interactions (CH⋯OS hydrogen bonds). The structural parameters of the sultone ring in SF5 CHCF 2 OS O2 are compared with those in CF 2 CF 2 OS O2 and CHFCF 2 OS O2.

The synthesis and characterization of new fluorinated surfactants based on SF5-aromatic system are presented for the first time.

The dependence of Tc on hydrostatic (He-gas) pressure is determined for the recently discovered organic superconductor β″-(ET)2SF5CH2CF2SO3 [ET = bis(ethylenedithio)-tetrathiafulvalene] with T c (0) ⋍ 5 K , yielding the pressure derivative d T c d P ⋍ −1.34 K kbar −1 . The present experiments also included κ-(ET)2Cu(NCS)2 where we find the extremely large value d T c d P ⋍ −3.84 K kbar −1 , in agreement with earlier studies. For both samples the pressure dependence Tc(P) does not depend on the temperature at which the pressure is changed.

Fluoroalkyl iodides are an important class of compounds used in the preparation of large numbers of fluoro-organo and fluoro-organometallic derivatives. We report the synthesis of several SF 5 -containing fluoroalkyl iodides derived from an improved synthesis of SF 5 CF 2 CF 2 I. They are: SF 5 CF 2 CF 2 CH 2 CH 2 I, SF 5 CF 2 CF 2 CF 2 CF 2 I, SF 5 CF 2 CF 2 (CH 2 CH 2 ) 2 I, SF 5 CF 2 CF 2 CH=CHI/isomer and SF 5 CF 2 CF 2 CHFCF 2 I/isomer. In addition, the higher homologs SF 5 (CF 2 ) 6 I, SF 5 CF 2 CF 2 (CHFCF 2 ) 2 I/isomer and SF 5 CF 2 CF 2 (CH 2 CH 2 ) 3 I have been identified.

A new approach to the synthesis of organic superconductors has recently been pioneered which involves the use of large, discrete, molecular anions as the charge-compensating entities in these charge transfer salts. The organic electron-donor molecule bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF or ET) has been electrocrystallized with the novel organometallic M(CF3)4 (M = Cu, Ag, and Au) anions in a variety of 1,1,2-trihaloethane solvents. Over twenty organic superconductors have been synthesized which can be described by the general formula (ET) 2 M(CF 3 ) 4 (1,1,2-trihaloethane). These solvated salts are shown to have highly anisotropic physical properties which can be tuned via modifications of each of their three molecular components: ET electron donor molecule, M(CF3)4 anion, and neutral 1,1,2-trihaloethane solvent molecule. Superconductivity has also been observed in an ET salt containing the discrete SF 5 CH 2 CF 2 SO 3 - anion with an onset temperature near 5.2 K.

For the first time, the (E)-1,2-difluoro-2-(pentafluoro-λ6-sulfanyl)ethenyl group has been bonded to λ3σ3 phosphorus using a Grignard reagent. Similar phosphorus derivatives containing the (Z)-1,2,3,3,3-pentafluoropropenyl moiety were also synthesized for comparison. In three cases, hexafluoroacetone was added to form 4,4,5,5-tetrakis(trifluoromethyl) 1,3,2λ5σ5-dioxaphospholanes. © 1997 John Wiley & Sons, Inc. Heteroatom Chem 8:467–471, 1997

The reaction of 3,3-bis(trifluoromethyl)-1,1,2,4,4,4-hexafluoro-1-butylene and nonafluoro- n -butoxy-1,1,2-trifluoroethylene with tris(trimethylsilyl)phosphite gave fluorotrimethylsilane and the respective (Z)-alkenylbis(trimethylsilyl)phosphonates. In one case hydrolysis afforded the free phosphonic acid (CF 3 ) 3 CCF = CFP(O) (OH) 2 . Using tri- n -butylphosphine and boron trifluoride etherate, 3,3-bis(trifluoromethyl)-1,1,2,4,4,4-hexafluoro-1-butylene and nonafluoro- n -butoxy-1,1,2-trifluoroethylene were converted into the corresponding phosphonium tetrafluoroborates, which when reacted further with iodine in the presence of Na 2 CO 3 gave the iodo derivatives (CF 3 ) 3 CCF = CFI and C 4 F 9 OCF = CFI.

The geometric structures and conformational properties of trifluoromethanesulfonic anhydride, (CF 3 SO 2 ) 2 O, and bis(trifluoromethylsulfonyl)difluoromethane, (CF 3 SO 2 ) 2 CF 2 have been studied by gas electron diffraction (GED) and ab initio calculations ( HF 3–21 G ∗ ). The calculations predict for both systems two stable conformers with C 2 symmetry and one with C 1 symmetry. In both compounds structures with C 2 symmetry and dihedral angles SOSC ≈ 100° ((CF 3 SO 2 ) 2 O) and SCSC ≈ 150° ((CF 3 SO 2 ) 2 CF 2 ) are lowest in energy. According to the GED analyses the dominant conformer of (CF 3 SO 2 ) 2 O possesses C 2 symmetry with SOSC dihedral angles of 99.1(14)°. The presence of up to 30% of the two other conformers cannot be excluded; for (CF 3 SO 2 ) 2 CF 2 only one conformer with C 2 symmetry and SCSC dihedral angles of 143(2)° is observed. A complete set of geometric parameters is given.

LiCH(SO{sub 2}CF{sub 3}){sub 2} is prepared by reaction of CH{sub 2}(CF{sub 3}SO{sub 2}){sub 2} with Li{sub 2}CO{sub 3} and the product identity confirmed by nuclear magnetic resonance, infrared, and elemental analysis. Differential scanning calorimetry/thermogravometric analysis data indicate a decomposition temperature near 280 C under N{sub 2}. PEO{sub x}LiCH(SO{sub 2}CF{sub 3}){sub 2} complexes show ionic conductivities as high, or higher than, those derived from other plasticizing salts, with {sigma} near 10{sup {minus}4} ({Omega} cm){sup {minus}1} at 30 C and 10{sup {minus}3} ({Omega} cm){sup {minus}1} at 80 C for the x = 16 complex. Differential scanning calorimetry data indicate that the polymer-salt complexes exhibit reduced crystallinity at ambient temperature and show minor crystalline phases at higher salt concentrations. Glass transition temperatures increase with salt content for the complexes. Cyclic voltammetry shows an electrolyte stability window of approximately 4.5 V.

The synthesis and characterization of a novel fluoroacrylate ester containing the fluorosulfonyl group (SO 2 F) has been carried out. This ester, H 2 CCHC(O)O(CH 2 ) 2 (CF 2 ) 2 O(CF 2 ) 2 SO 2 F ( 1 ), was successfully polymerized in bulk and as a film. Infrared, mass and NMR spectra are presented in order to support the assigned structures.

Photoinitiated polymerization of fluorinated aliphatic epoxides bearing terminal sulfonyl fluoride groups with a commercial cycloaliphatic diepoxide (Cyracure UVR-6110) results in highly cross-linked glassy films. Depth-dependent surface analysis using XPS shows that these films are highly enriched in their outer molecular surface regions with sulfonyl fluoride groups. Films prepared with 17 wt % and higher sulfonyl fluoride epoxide monomers exhibit compositions close to that of a pure 100% photopolymerized sulfonyl fluoride epoxide monomer in the outer 50 A of the film. Even a film prepared with 1 wt % sulfonyl fluoride monomer exhibits a few angstroms thick overlayer of sulfonyl fluoride. FTIR (attenuated total reflectance) spectra exhibit infrared signatures consistent with these data. Secondary ion mass spectra exhibit peaks associated with perfluoro and sulfonyl fluoride moieties, supporting overlayer enrichment of these species within the sampling depth of this method (outer 15 A). Such extreme surf...

The gas phase structure of trifluoroethylene sultone, (1) (3,4,4-trifluoro-1,2-oxathietane-2,2-dioxide) was determined by gas electron diffraction, and the four-membered ring was found to be planar. The following ring parameters (ra distances and ∠α angles with 3σ uncertainties) were derived in the electron diffraction analysis: CO = 1.41 A (ass.), CC = 1.541(18) A, SO = 1.652(5) A, SC = 1.822(8) A, SCC = 86.2(15)°, CCO = 97.1(28)°, COS = 97.5(21)°, and OSC = 79.1(8)°. New spectral data (IR, NMR) of 1, its acyclic isomer FSO2CFHC(O)F (2), and the related anhydride, FSO2OSO2CFHC(O)F (3), are reported. New esters containing the fluorosulfonyl function, FSO2CFHC(O)OCH2CF3 (4), FSO2CFHC(O)OCH2CH = CH2 (5), and (FSO2CFHC(O)OCH2CHCH2)n (6) have been prepared and characterized. Trifluorethylensulton: Struktur und Chemie Die Struktur des Trifluorethylensultons (1) (3,4,4-Trifluor-1,2-oxathietan-2,2-dioxid) wurde durch Elektronenbeugung in der Gasphase bestimmt. Der viergliedrige Ring ist planar. Folgende Parameter (ra Abstande und ∠α-Winkel mit der Fehlergrenze von 3σ) wurden erhalten: CO = 1,41 A (ass), CC = 1,541(18) A, SO = 1,652(5) A, SC = 1,822(8) A, SCC = 86,2(15)°, CCO = 97,1(28)°, COS = 97,5(21)° und OSC = 79,1(8)°. Neue spektroskopische Daten (IR, NMR) fur 1, sein acyclisches Isomer FSO2CFHC(O)F (2), und das Anhydrid FSO2OSO2CFHC(O)F (3) werden mitgeteilt. Neue Ester mit der Fluorsulfonyl-Funktion, FSO2CFHC(O)OCH2CF3 (4), FSO2CFHC(O)OCH2CH = CH2 (5), und (FSO2CFHC(O)OCH2CHCH2)n (6) wurden dargestellt und charakterisiert.

We have measured the high resolution spectrum of ethynylsulphurpentafluoride, SF 5 CCH, in both the fundamental and the first overtone of the acetylenic CH stretch in a collimated, supersonic molecular beam. The intramolecular redistribution of vibrational energy is discussed in relation to previous experimental results for other similar molecules and theoretical models. The absence of low order anharmonic resonances and the long (⪢ 1 ns) lifetime derived from the spectra support a previously proposed correlation between these two molecular properties.