Perfluororganozink-verbindungen: darstellung und eigenschaften von (Rf)2Zn-komplexen (Rf = CF3, C2F5, C3F7, C6F5) [1]

A new method for the preparation of bis(perfluoroorgano) zinc compounds is described: CF₃I and C₆F₅I react with dialkylzinc in the presence of a Lewis base quantitatively to give (CF₃)₂Zn and (C₆F₅)₂Zn complexes, while the analogous reactions with C₂F₅I and iC₃F₇I do not yield the pure compounds. ¹H, ¹⁹F n.m.r, i.r. and Raman spectra are presented.     

Synthesis and molecular structures of heptafluoroisopropylated fullerenes: C60(i-C3F7)8, C60(i-C3F7)6, and C60(CF3)2(i-C3F7)2

One isomer of C₆₀(i-C₃F₇)₈, three isomers of C₆₀(i-C₃F₇)₆, and the first mixed perfluoroalkylated fullerene, C₆₀(CF₃)₂(i-C₃F₇)₂, have been isolated by HPLC from a mixture prepared by reaction of C₆₀ with heptafluoroisopropyl iodide in a glass ampoule at 260-290 °C. The molecular structures of the four new compounds have been determined by means of X-ray single crystal diffraction partially also by use of synchrotron radiation. Theoretical calculations at the DFT level of theory have been employed to rationalize the energetics of isomers and of C₆₀-R_f binding.     

A widely varying range of products in reactions of C6F5BrF2, C6F5IF2, and C6F5IF4 with Lewis acids of different strength

The relative fluoride donor ability: C₆F₅BrF₂ > C₆F₅IF₂ > C₆F₅IF₄ was outlined from reactions with Lewis acids of graduated strength in different solvents. Fluoride abstraction from C₆F₅HalF₂ with BF₃·NCCH₃ in acetonitrile (donor solvent) led to [C₆F₅HalF·(NCCH₃)_n][BF₄]. The attempted generation of [C₆F₅BrF]⁺ from C₆F₅BrF₂ and anhydrous HF or BF₃ in weakly coordinating SO₂ClF gave C₆F₅Br besides bromoperfluorocycloalkenes C₆BrF₇ and 1-BrC₆F₉. In reactions of C₆F₅IF₂ with SbF₅ in SO₂ClF the primary observed intermediate (¹⁹F NMR, below 0 °C) was the 4-iodo-1,1,2,3,5,6-hexafluorobenzenium cation, which converted into C₆F₅I and 1-IC₆F₉ at 20 °C. The reaction of C₆F₅IF₄ with SbF₅ in SO₂ClF below −20 °C gave the cation [C₆F₅IF₃]⁺ which decomposed at 20 °C to C₆F₅I, 1-iodoperfluorocyclohexene, and iodoperfluorocyclohexane. Principally, the related perfluoroalkyl compound C₆F₁₃IF₄ showed a different type of products in the fast reaction with AsF₅ in CCl₃F (−60 °C) which resulted in C₆F₁₄. Intermediate and final products of C₆F₅HalF_n−1 (n = 3, 5) with Lewis acids were characterized by NMR in solution. Stable solid products were isolated and analytically characterized.     

Synthesis and molecular structures of heptafluoropropylated fullerenes: C70(n-C3F7)8, C70(n-C3F7)6O, and C70(C3F7)4

Ampoule reactions of C₇₀ with n- and i-C₃F₇I were carried out at 250-310 °C. Two step HPLC separations allowed the isolation of several C₇₀(n-C₃F₇)_4-8 and C₇₀(i-C₃F₇)₄ compounds. Crystal and molecular structures of C₇₀(n-C₃F₇)₈-V, C₇₀(n-C₃F₇)₆O, C₇₀(n-C₃F₇)₄, and three isomers of C₇₀(i-C₃F₇)₄ have been determined by X-ray crystallography using synchrotron radiation. Molecular structures of the new compounds were compared with the known examples and discussed in terms of addition patterns and relative energies of their formation.     

Tieftemperatur-flüssigphase-fluorierung von (C6F5)2Te: Bildung von (C6F5)2TeF2, (C6F5)2TeF4 und (C6F11)2TeF4 [1]

(C₆F₅)₂Te reacts with elemental fluorine step by step to form the tellurium fluorides (C₆F₅)₂TeF₂, (C₆F₅)₂TeF₄ and (C₆F₁₁)₂TeF₄, which can be isolated in pure states. The intermediates (C₆F_11?2n)₂TeF₄ (n = 1,2) are detected spectroscopically. (C₆F₅)₂TeF₂ is also formed from the reaction of (C₆F₅)₂Te with XeF₂. The preparations, properties and ¹⁹F n.m.r. spectra of these new compounds are discussed, the mass and vibrational spectra are described.     

Dehalogenative aromatization of perchlorofluoroalicyclic compounds C6Cl6F6, C10Cl8F8 and C5Cl4F5N in the vapour phase or in solution

Dehalogenation of perhalogenated cyclohexanes C₆Cl₆F₆, 1-azacyclohexenes C₅Cl₄F₅N and bicyclo[4.4.0]dec-1(6)-enes C₁₀Cl₈F₈ in the vapour phase over iron filings at 350-500 °C and in solution with Zn and additivities (Cu, NiCl₂·6H₂O + bpy) at 80 °C (heterogeneous reaction) or with P(NEt₂)₃ at 20 °C (homogeneous reaction) was studied. In all cases, perfluoroarenes, chloroperfluoroarenes and dichloroperfluoroarenes (benzenes, naphthalenes and pyridines) were obtained in good overall yield.     

Die gas-chromatographische Analyse von Fluormethanen (CF4, CHF3, CH2F2, CH3F)

Ohne Zusammenfassung     

2,5-Dichloro-1-(ROSO2)benzene [R = C6H5, C6F5, and CH2(CF2)4H]: Synthesis, molecular structure, and solubility in supercritical CO2

Highly crystalline phenyl 2,5-dichlorobenzenesulfonate (PDBS, T_melt = 86-87 °C) and pentafluorophenyl 2,5-dichlorobenzenesulfonate (FPDBS, T_melt = 120-122 °C) were synthesized. Single-crystal X-ray molecular structure determinations show that both compounds have similar three-dimensional molecular structures; however, PDBS crystals are thin platelets and FPDBS crystals form hexagonal tube-like structures that are predominately hollow at one end. PDBS crystals exhibit offset π-stacking of the phenoxy-rings that form complete two-dimensional layers each two molecules thick. Hydrogen-bonding interactions are calculated at ∼3.2 Å between the C6-hydrogen and the sulfonyl-oxygen of a neighboring molecule. On the other hand, for FPDBS, π-stacking of the dichloro-substituted ring as well as dipole-dipole interactions of the fluorinated-phenoxy rings appears to be the predominate intermolecular interactions. Neither structure exhibits any kind of side-on interaction of the phenyl rings. PDBS and FPDBS exhibit melting point depressions of 26 and 40 °C, respectively, in the presence of supercritical CO₂. Although both sulfonates exhibit high solubility in CO₂, much lower pressures are needed to dissolve FPDBS compared to PDBS. For example, at 100 °C FPDBS dissolves at 4750 psia and PDBS dissolves at 11,000 psia. The solubility data reinforce the observation that fluorinating a compound can significantly lower the conditions needed to dissolve that compound in CO₂.     

Vapour-liquid equilibrium data for the systems C2H6 + N2, C2H4 + N2, C3H8 + N2, and C3H6 + N2

High pressure vapour-liquid equilibrium data for the C₂H₆ + N₂, C₂H₄ + N₂, C₃H₈ + N₂, and C₃H₆ + N₂ systems are presented. The data are obtained isothermally in the range from 200 K to 290 K. For each point of data, temperature, pressure and liquid and vapour phase mole fractions are measured.Values for the vapour phase mole fractions are calculated from the obtained pressure, temperature and liquid phase mole fractions. The calculated values are compared with the experimental results, and it is found that the average mean deviation between calculated and experimental mole fractions is less than 0.009 for the systems considered in this work.     

Ab initio direct dynamics studies on the hydrogen abstraction reactions of CF2H2 and CF3H with F atom

The dynamic properties of the hydrogen abstraction reactions of CF₂H₂ and CF₃H with F atom are investigated in the temperature range of 182–2000 K. The minimum-energy path (MEP) is optimized at MP2/6-311 G(d, p) level, then the energy profiles are refined at the CCSD(T)/6-311++G(3df, 2pd) level (single-point). The theoretical rate constants, which are calculated by the variational transition state theory (VTST) including the small curvature tunneling (SCT) correction, are in good agreement with the experimental ones. It is found that the rate constant of the CF₂H₂ + F reaction are larger than that of the CF₃H + F reaction and the activation energies exhibit in the just opposite order. This phenomenon can be rationalized by the hardness η of the halomethane molecules. The comparison of the two reactions with the CFH₃ + F reaction is made. It is found that the rate constants decrease in the order of CFH₃ + F > CF₂H₂ + F > CF₃H + F. The effect of fluorine substitution leads to a dramatic increase in the activation energy and a decrease in the preexponential factor. We hope that present theoretical studies for these compounds can give further information concerning how fluorine substitution affects the rate constants of hydrogen abstraction reactions.     

Multiconfiguration self-consistent wavefunctions for CH4, C2H4 and C2H6

The results of several MC SCF calculations on CH₄, C₂H₄ and C₂H₆ with minimun bases of Slater type AO's are reported. The computing method is a quadratically convergent process. Better final energies are obtained if localized MO's are used.     

Reaction of C60 with KMnF4 : Isolation and characterization of a new isomer of C60F8 and re-evaluation of the structures of C60F7(CF3) and the known isomer of C60F8

The volatile fluorofullerene products of high-temperature reactions of C₆₀ with the ternary manganese(III, IV) fluorides KMnF₄, KMnF₅, A₂MnF₆ (A⁺ = Li⁺, K⁺, Cs⁺), and K₃MnF₆ were monitored as a function of reaction temperature, reaction time, and stoichiometric ratio by in situ Knudsen-cell mass spectrometry. When combined with fluorofullerene product ratios from larger-scale (bulk) screening reactions with the same reagents, an optimized set of conditions was found that yielded the greatest amount of C₆₀F₈ (KMnF₄/C₆₀ mol ratio 28-30, 470 °C, 4-5 h). Two isomers of C₆₀F₈ were purified by HPLC, one of which has not been previously reported. Quantum chemical calculations at the DFT level combined with 1D and 2D ¹⁹F NMR, FTIR, and FT-Raman spectroscopy indicate that the C₆₀F₈ isomer previously reported to be 1,2,3,8,9,12,15,16-C₆₀F₈ is actually 1,2,3,6,9,12,15,18-C₆₀F₈, making it the first high-temperature fluorofullerene with non-contiguous fluorine atoms. The new isomer, which was found to be 1,2,7,8,9,12,13,14-C₆₀F₈, is predicted to be 5.5 kJ mol⁻¹ more stable than 1,2,3,6,9,12,15,18-C₆₀F₈ at the DFT level. In addition, new DFT calculations and spectroscopic data indicate that the compound previously isolated from the high-temperature reaction of C₆₀ and K₂PtF₆ and reported to be 16-CF₃-1,2,3,8,9,12,15-C₆₀F₇ is actually 18-CF₃-1,2,3,6,8,12,15-C₆₀F₇.     

Absolute dipole differential oscillator strengths for inner shell spectra from high resolution electron energy loss studies of the freon molecules CF4, CF3Cl, CF2Cl2, CFCl3 and CCl4

Absolute differential photoabsorption oscillator strengths (cross sections) for the F 1s, C 1s, and Cl 2p, 2s inner shells of the freon molecules CF₃Cl, CF₂Cl₂ and CFCl₃ have been derived from high resolution electron energy loss spectra obtained under dipole dominated conditions of high impact energy (3 keV) and zero degree mean scattering angle. Differential oscillator strengths have also been obtained from earlier reported electron energy loss spectra for CF₄ and CCl₄. The spectra are analyzed using the MO picture and the potential barrier model.     

Substitution in barium-fluoride apatite: The crystal structures of Ba10(PO4)6F2, Ba6La2Na2(PO4)6F2 and Ba4Nd3Na3(PO4)6F2

The crystal structures of the apatites Ba₁₀(PO₄)₆F₂(I), Ba₆La₂Na₂(PO₄)₆F₂(II) and Ba₄Nd₃Na₃(PO₄)₆F₂ (III) have been determined by single-crystal X-ray diffraction. All three compounds crystallize in a hexagonal apatite-like structure. The unit cells and space groups are: I, a = 10.153(2), c = 7.733(1)Å, $\text{P6}{}_3\text{m}\text{; a = 9.9392(4), c = 7.4419(5)}$Å, $\text{P}\text{6}$; III, a = 9.786(2), c = 7.281(1)Å, $\text{P}\text{3}$. The structures were refined by normal full-matrix crystallographic least squares techniques. The final values of the refinement indicators R_w and R are: I, R_w = 0.026, R = 0.027, 613 observed reflections; II, R_w = 0.081, R = 0.074, 579 observed reflections; III, R_w = 0.062, R = 0.044, 1262 observed reflections.In I, the Ba(1) atoms located in columns on threefold axes, are coordinated to nine oxygen atoms; the Ba(2) sites form triangles about the F site and are coordinated to six oxygen atoms and one fluoride ion. The fluoride ions are statistically displaced ～0.25 Å from the Ba(2) triangles. This displacement of the F ions is analogous to the displacement of OH ion in Ca₁₀(PO₄)₆(OH)₂.The structures of II and III contain disordered cations. In II there is disorder between La and Na in the column cation sites as well as triangle sites. In III, Nd and Na ions are ordered in the column sites, but there is disorder among Ba and the remaining Nd and Na ions in the triangle sites to give an average site population of $\text{2}\text{3}\text{Ba}\text{,}\text{1}\text{6}\text{Nd}\text{,}\text{1}\text{6}\text{Na}$. The coordination of the rare earth ions and Na ions in the ordered column sites are nine and six oxygens, respectively, in accord with the greater charge of the rare earth ions as compared with Na. The F ions in both II and III suffer from considerable disorder in position, and their locations are not precisely known.     

Energy distribution in CF2(1B1) from the triplet-triplet annihilation of CF2(3B1) and from the vacuum ultraviolet photolysis of C2F4

Spectral analysis of the CF₂(¹B₁) → CF₂(¹A₁) transition showed that the energy distribution found in the v₂ bending vibration (v'₂ ? 3) of CF₂(¹B₁) produced from the triplet-triplet annihilation of CF₂(³B₁) and from the vacuum ultraviolet photolysis of C₂F₄ are approximately statistical and closely related to each other.     

Die Trennung von Ar und O2 sowie CH4, C2H6, C3H8 und C4H10

Ohne Zusammenfassung     

The geometry, vibrational frequencies, thermochemistry, quadrupole moments and electronic structure of C2Na2: Comparison with C2Li2, C2H2, C2F2 and C2Cl2

The electronic structure of Na₂C₂ is studied using ab initio electronic structure methods and is compared to the companion molecule Li₂C₂. Both the linear D_∞h and planar structures are minima on the ground state potential surface with the planar D_2h conformation being the lowest energy form, similar to Li₂C₂. At the CCSD(t) level the planar form is more stable that the linear by 11.2 kcal/mol as compared with 7.34 kcal/mol for Li₂C₂. Both molecules are significantly ionic. The vibrational frequencies, atomization energy at 0 K, D₀, and the standard enthalpy of formation, are calculated and compared to those of Li₂C₂ as well as HCCH, FCCF and ClCCCl. We find D₀ and to be 331.1 and 84.92 kcal/mol for Li₂C₂ and 298.3 and 93.25 kcal/mol for Na₂C₂. We calibrate these by calculating the same quantities for HCCH, FCCF and ClCCCl.     

AB initio molecular orbital studies of CF3O2H,CF3O2F and CF2(OF)2

Ab initio calculations employing an extended 4-31G basis set have been applied to the highly fluorinated molecules, CF₃O₂H, CF₃O₂F and CF₂(OF)₂. Partial geometry optimizations have also been carried out on these molecules allowing a comparison between theory and the recently completed gas-phase electron diffraction results. The O-O bond distance in CF₃O₂ H is found to be longer (by 0.02 Å) than the corresponding bond in CF₃O₂F while the CO bond is found to be shorter (by 0.02 Å) in CF₃O₂H. The OF bond in CF₃O₂F is found to be longer (by 0.03–0.04 Å) than the corresponding bond in CF₃OF or F₂O. Torsional barriers have been computed for CF₃O₂H and CF₃O₂F with the aid of Fourier analysis of the potential curves. CF₃O₂H is found to have a torsional potential about the peroxide bond rather similar to that found for H₂O₂ while in CF₃O₂F the cis and trans barriers are predicted to be much larger (14.6 and 8.4 kcal mol^?1, respectively). The threefold barrier to rotation of the CF₃ group in CF₃O₂F is predicted to be 4.4 kcal mol^?1. Various conformations of CF₂(OF)₂ have also been studied with conformations consistent with the operation of the gauche-effect being most stable. Bond separation energies and molecular properties have also been computed for these molecules.     

Synthesis and reactivity of [N(C6H4Br)3][B(C6F5)4]: the X-ray crystal structure of [Fe(C5H5)2][B(C6F5)4]

A new chemical oxidant [N(4-C₆H₄Br)₃][B(C₆F₅)₄], was prepared and used to synthesize [Fe(C₅H₅)₂][B(C₆F₅)₄]. The crystal structure of [Fe(C₅H₅)₂][B(C₆F₅)₄] was determined.     

Trifluoromethylperoxyphoshoryl difluoride,CF3OOPOF2 and trifluoromethoxyphosphoryl difluoride,CF3OPOF2

The new compounds CF₃OOPOF₂ and CF₃OPOF₂ have been prepared by the reaction of trifluoromethyl-hydroperoxide, CF₃OOH, with μ-oxo-bis-(phosphoryl difluoride), P₂O₃F₄, and difluorophosphine-μ-oxo-phosphoryl difluoride, P₂O₂F₄. Infrared and NMR spectra, physical properties and some chemical reactions are reported for the compounds.