Ir matrix isolation spectra of some perfluoro organic free radicals. Part III. n-C3F7 and iso-C3F7

The perfluoro radicals n-C₃F₇ and iso-C₃F₇ have been prepared by pyrolyzing the corresponding iodides in a platinum effusion tube at temperatures between 450–550°C and isolated in argon matrices. By eliminating absorption bands attributed to known fluorine compounds and applying relative absorption band intensity correlations, several absorption bands have been assigned, some 30 to n-C₃F₇ and 29 to iso-C₃Fe₇, in the spectral range 2000–200 cm^-1. A tentative vibrational assignment is presented for both species on the assumption of C_s symmetry. Some thermodynamic implications of the findings are also discussed.     

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.     

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.     

Liquid column-chromatographic separation and determination of long-chain primary n-alkylamines (n-C10H21NH2 to n-C22H45NH2) after their fluorescence derivatization with salicylaldehyde diphenylboron chelate

Summary Long-chain primary n-alkylamines (fatty amines) were separated by reversed-phase high-performance liquid chromatography (RP HPLC) after derivatization with salicylaldehyde diphenylboron chelate to fluorescent chelate-like azomethine compounds. Thin-layer chromatography was used as a pilot procedure. A RP-18 HPLC column and methanol/water mixtures are suitable for the separation of the derivatized fatty amines up to n-C₂₂H₄₅NH₂, they can be detected fluorimetrically. Only n-alkylamines of specific chain length ranges are separable under isocratic conditions with water concentrations of 0 to 25% by volume. On the other hand gradient elution makes it possible to separate all the n-alkylamines investigated within 45 min, thus allowing quantitative determination. The peak areas are proportional to concentrations in the range 2 × 10^–6 to 8 × 10^–5 mol/l. The determination of derivatized n-dodecylamine (concentration 5 × 10^–5 mol/l) can be performed with a relative standard deviationS _rel = 0.023 ( 2.3%). The smallest determinable concentration varies from 1.5 × 10^–6 for n-C₁₂H₂₅NH₂ to 4.5 × 10^–6 mol/l for n-C₁₈H₃₇NH₂ (sample volume 50 l).

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Flüssigkeits-chromafographische Trennung und Bestimmung von langkettigen primären n-Alkylaminen (n-C₁₀H₂₁NH₂ bis n-C₂₂H₄₅NH₂) nach ihrer Fluorescenzderivatisierung mit Salicylaldehyd-diphenylborchelat

Zusammenfassung Langkettige primäre n-Alkylamine (Fettamine) wurden nach der Derivatisierung mit Salicyl-aldehyd-diphenylborchelat zu fluorescierenden chelatartigen Azomethinverbindungen mit Hilfe der reversed-phase-Hochleistungsflüssigkeits-Chromatographie (RP-HPLC) getrennt. Als Pilot-Verfahren diente die Dünnschicht-Chromatographie. Für die Trennung der derivatisierten Fettamine bis n-C₂₂H₄₅NH₂ und deren fluorimetrischer Detektion sind eine RP-18-HPLC-Säule und Methanol/Wasser-Gemische geeignet. Unter isokratischen Bedingungen sind bei Wassergehalten zwischen 0 und 25 Vol.-% nur n-Alkylamine bestimmter Kettenlängenbereiche trennbar. Dagegen ermöglicht die Gradientelution eine für quantitative Bestimmungen geeignete Trennung aller angewendeten n-Alkylamine innerhalb von 45 min. Die Peakflächen sind den Konzentrationen im Bereich 2 · 10^–6 bis 8 · 10^–5mol/l proportional. Die Bestimmung von derivatisiertem n-Dodecylamin (Konzentration 5 · 10^–5 mol/l) ist mit einer relativen StandardabweichungS _rel = 0,023 ( 2,3%) durchführbar. Die kleinste bestimmbare Konzentration beträgt 1,5 · 10^–6 für n-C₁₂H₂₅NH₂ bis 4,5 · 10^–6 mol/l für n-C₁₈H₃₇NH₂ (Probenvolumen 50 l).

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Boron chelates and boron metal chelates, Part XVII. For Part XVI see ref. [1]

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Dedicated to Prof. Dr. H. Hartkamp on the occasion of his 60th birthday     

Analyse des sites de KLu3F10 et BaCaLu2F10 par spectroscopie de l'ion Eu3+

The Eu³⁺ ion is used as a structural probe, in order to state precisely the symmetry at the different cationic sites in the KLu₃F₁₀ and BaCaLu₂F₁₀ compounds. The emission and excitation spectra recorded at 4.4, 77, and 295°K are analyzed and the experimental data for both systems are compared. The energy levels of the Eu³⁺ ion in KLu₃F₁₀ are given. It is shown that Eu³⁺ ions enter three different sites in BaCaLu₂F₁₀. The nature of these sites is discussed.     

UO2F4: A new uranyl complex ion

The synthesis, vibrational and electronic spectra of [(CH₃)₄N]₂ UO₂F₄ are described. The data indicate that this compound contains the previously unknown UO₂F₄²⁻ ion which has D_4h symmetry.     

Compressibilities of disordered fluoride pyrochlores NaCdZn2F7 and NaCaMg2F7

The compressibilities of disordered pyrochlores NaCaMg₂F₇ and NaCdZn₂F₇ (both , Z=8) have been studied with X-ray single-crystal and powder diffraction using diamond anvil cells to 6.5 and 9.0 GPa at room temperature, respectively. The compressibility data are fitted with the Murnaghan equations of state. The zero-pressure bulk modulus B₀ and the unit-cell volume at ambient pressure V₀ (for the fixed first pressure derivative of the bulk modulus B′=4.00) are equal to 83(2) GPa and 1107.12(1.33) Å³ for NaCdZn₂F₇ and to 83(5) GPa and 1079.29(2.62) Å³ for NaCaMg₂F₇. Upon decreasing the unit-cell volume, the positional x parameter of the F(2) atom increases in NaCdZn₂F₇ but is constant in NaCaMg₂F₇. In both cases, the (Na,Cd)F₈ and (Na,Ca)F₈ cubes become more regular and are softer than the ZnF₆ and MgF₆ octahedra, respectively. Both materials are structurally stable at least to the respective highest pressures reached in this study. These observations are compared to the high-pressure behavior of oxide pyrochlores.     

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.     

Crystal structures of NaBaCr2F9 and NaBaFe2F9: Structural correlations with other enneafluorides,particularly with KPbCr2F9

NaBaCr₂F₉ and NaBaFe₂F₉ are monoclinic (SG $\text{P2}{}_1\text{n}$, No. 14). Lattice constants are found to be a = 7.318(2) Å, b = 17.311(4) Å, c = 5.398(1) Å, β = 91.14°(3) for chromium, and a = 7.363(2) Å, b = 17.527(4) Å, c = 5.484(1) Å, β = 91.50°(5) for iron. The structures were solved from 507 and 1113 X-ray reflections, respectively, for the Cr and Fe compounds; the corresponding R_w values are 0.025 and 0.037. The network is built from tilted double cis chains of octahedra (M₂F₉)^3n?_n [M = Cr, Fe], linked by Na⁺ and Ba²⁺ ions. The structures are compared to the previously described structures, particularly KPbCr₂F₉, whose symmetry and parameters are different. The difference is analyzed first in terms of tilted octahedra, but principally in terms of bond strengths and steric activity of the Pb²⁺ lone pair. A mechanism is proposed for the transformation between the structures of NaBaCr₂F₉ and KPbCr₂F₉.     

Coordination chemistry of higher oxidation states. 10 [1]. Oxofluoroanions of osmium(VIII) [OsO4F2]2− and [OsO3F3]−

Trioxotrifluoroosmates(VIII) M[OsO₃F₃] (M = Cs, Rb, K) have been prepared by direct combination of OsO₃F₂ and the appropriate alkali fluoride MF. The reaction of OsO₄ with M′F (M′ = Cs, Rb) in aqueous solution produces the tetraoxodifluoroosmates(VIII) M′₂[OsO₄F₂]. On the basis of their vibrational spectra the assignment of a $\text{fac}$ (C_3v) structure to [OsO₃F₃]^? and a $\text{cis}$ (C_2v) to [OsO₄F₂]^2? is proposed. The electronic spectra of the anions have been recorded and are interpreted using the optical electronegativity concept.     

Structure cristalline de RbSb2F7

The crystal structure of RbSb₂F₇ was determined by single crystal X-ray diffraction methods. The antimony atom coordination is of the AX₆E type, either monocapped octahedral or the distorded 2.2.2.1 arrangement. The anion (Sb₂F₇)^x-_x forms a polymeric layer parallel to the bc plane. There is an Sb-F-Sb bridge intermediate between the symmetric and asymmetric bridges of CsSb₂F₇ and KSb₂F₇ respectively.     

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.     

The ESR spectrum of the C5F5 radical

Experimental results of an investigation of the ESR spectrum of the pentafluorocyclopentadienyl radical C₅F₅ in various liquid and solid matrices are reported. At temperatures above 120 K the ESR spectra indicate a five-fold symmetry with a fluorine isotropic splitting of 16 G and an isotropic g tensor of 2.0041. From liquid solutions a value A_iso¹³C ≈ 2.1 G for the isotropic coupling of the ¹³C₁ species in natural abundance was found. The ESR spectra exhibit a pronounced temperature dependence, which is interpreted by lineshape analysis to originate from an anisotropic hyperfine interaction tensor of fluoroine, partially averaged by a uniaxial rotational reorientation. From ESR spectra of polycrystalline samples the principal value A6 = 57.5–58.3 G depending on the matrix was derived.     

Sol-gel synthesis of K3InF6 and structural characterization of K2InC10O10H6F9, K3InC12O14H4F18 and K3InC12O12F18

K₃InF₆ is synthesized by a sol-gel route starting from indium and potassium acetates dissolved in isopropanol in the stoichiometry 1:3, with trifluoroacetic acid as fluorinating agent. The crystal structures of the organic precursors were solved by X-ray diffraction methods on single crystals. Three organic compounds were isolated and identified: K₂InC₁₀O₁₀H₆F₉, K₃InC₁₂O₁₄H₄F₁₈ and K₃InC₁₂O₁₂F₁₈. The first one, deficient in potassium in comparison with the initial stoichiometry, is unstable. In its crystal structure, acetate as well as trifluoroacetate anions are coordinated to the indium atom. The two other precursors are obtained, respectively, by quick and slow evaporation of the solution. They correspond to the final organic compounds, which give K₃InF₆ by decomposition at high temperature. The crystal structure of K₃InC₁₂O₁₄H₄F₁₈ is characterized by complex anions [In(CF₃COO)₄(OH_x)₂]^(5−2x)− and isolated [CF₃COOH_2−x]^(x−1)− molecules with x=2 or 1, surrounded by K⁺ cations. The crystal structure of K₃InC₁₂O₁₂F₁₈ is only constituted by complex anions [In(CF₃COO)₆]³⁻ and K⁺ cations. For all these compounds, potassium cations ensure only the electroneutrality of the structure. IR spectra of K₂InC₁₀O₁₀H₆F₉ and K₃InC₁₂O₁₂F₁₈ were also performed at room temperature on pulverized crystals.     

Vibrational and calorimetric study of phase transitions in n-C6F14 and n-C8F18 crystals

Heat capacities of n-perfluorohexane and n-perfluorooctane were measured from 4.2 K to room temperature. One solid—solid transition is found for n-C₆H₁₄,two for n-C₈F₁₈. Spectra show that the molecules have the same conformations in the two forms of n-C₆F₁₄. Several isomers are present in the high-temperature forms of n-C₈F₁₈;thus transitions in this compound have order—disorder character.     

Ab Initio calculation of molecular, thermodynamic, and kinetic parameters of CF, CF2, CF3, and C2F5 radicals and CF4, CF3I, C2F4, and C2F6 molecules in gas

Enthalpies of formation of ground states of the gaseous particles CF, CF₂, C₂F₅, CF₄, CF₃I, C₂F₄, and C₂F₆ were calculated by ab initio method in the CCSD(T) approximation with extrapolation to the full basis and regard to the correlation energy. Their equilibrium geometrics, frequencies of normal vibrations, and other values were found by the B3LYP/aug-cc-pvdz method, from which thermodynamic functions within the range of 0–6000 K were calculated. Equilibrium constants were calculated from these functions, and then the information on the rate constants in the limit of high pressures was obtained.     

Trans-N2F2 and cis-N2F2: A green's function calculation on their photoelectron spectra

The vertical valence ionization potentials of trans-N₂F₂ and cis-N₂F₂ have been computed by a many-body Green function method. For trans-N₂F₂ the agreement with experiment is very satisfactory in general and the calculations permit an analysis and assignment of the experimental photoelectron spectrum. The ionization potentials of cis-N₂F₂ are predictions. The ordering of the ionization potential is for trans-N₂F₂ 5ag(n₊), 2a_u(π), 4b_u(n_?), 4ag, 1b_g(π), 1a_u(π), 3b_u, 3a_g, 2b_u and for cis-N₂F₂ 4b₂ (n_?), 2b₁ (π) + 5a₁(n+), 3b₂, 1a₂ (π), 1b₁(π), 4a₁, 3a₁, 2b2, n₊ and n_? denote lone pairs on the N atoms except for the 4b_u(n_?) orbital which has the largest contribution from the F atoms.     

Thermal behaviour of (NH4)3VO2F4 and Na(NH4)2VO2F4

The thermal behaviour of (NH₄)₃VO₂F₄ and Na(NH₄)₂VO₂F₄ was investigated using TG, DTA and DSC techniques. The occurrence of a first order phase transition with the onset of decomposition in both the compounds is confirmed. The temperature, energetics and hysteresis of the transition are obtained. A possible path for the thermal degradation is given for both the compounds, and the residues are identified.     

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.     

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.