Les fluorations comparees des chloropyrimidines et de la chloro-s-triazine en milieu de fluorure de potassiun solide

The fluorinations of tetrachloropyrimidine, 2,4,6-trichloropyrimidine and trichloro-s-triazine were carried out in sealed tubes with KF in presence of inert gas and then compared. The fluorinated derivatives C₄F_xCl_yN₂ with x + y = 4, 0?x<4 , C₄HF_xCl_yN₂ with x + y = 3, 0?x?3 and C₃F_xCl_yN₃ with x + y = 3, 0?x?3 were obtained. The influence of contact time, temperature and concentration of the ion F^? were investigated and compared; the molar yields were found to be always higher than 50% in our experimental conditions. We compare with the fluorinations of 2, 4 and 4, 6-dichloropyrimidine. It is possible to obtain directly, in good proportions, such fluorinated derivatives as 5-chlorotrifluoropyrimidine, trifluoropyrimidine and others. At high temperature (400°C for 16^h), tetrachloropyrimidine, in presence of KF, gave products of pyrolysis and condensation such as the fluorinated derivatives of C₆Cl₆ and C₅Cl₅N : C₆FCl₅, C₆F₂Cl₄ ··· or C₅FCl₄N, C₅F₂Cl₃N ···     

Synthesis and Structure of the new Fluoride Bromide Ba6.668(2)Ca0.332(2)F12Br2 and Solid Solutions with Composition Ba7−xCaxF12(ClyBr1−y)2 with x = ∼0.5, 0 < y < 1

Crystals of the chemical composition Ba₇F₁₂Cl₂ were modified by adding a small amount of Ca²⁺ to allow the synthesis of the corresponding bromine compound Ba^[Ca]₇F₁₂Br₂. These samples were prepared in a NaBr flux and characterized by single crystal x‐ray diffraction. The new structure crystallizes in a disordered arrangement in the hexagonal space group P6₃/m (176). The calcium ion has a coordination number of 6. Solid solutions on the heavy halide position can be synthesised in a NaCl/NaBr flux to obtain the compounds Ba_7?xCa_xF₁₂(Cl_yBr_1?y)₂ with x = ～0.5 and 0 < y < 1. Regardless the amount of calcium used in the preparation process, the Ca stoichiometry in the compound is always between 0.3 and 0.5. The lattice parameters differ depending on the Ca‐ and Br‐content between 1053.81(5) ? a = b ? 1058.93(3) pm and 421.21 ? c ? 426.78(3) pm.     

35Cl NQR and mobility of partly chlorinated methyl groups in crystals

The temperature dependence of the ³⁵Cl NQR frequencies, their temperature coefficients, and spin-lattice relaxation times was studied for crystalline compounds Cl_xH_3?xCR with RC₆H₅, COOH, and CONH_2?y(CH₃)_y(x=1,2 and y=0,1,2) in the temperature range from 77 K to the sample melting points. It is found that for the mono- and dichloromethyl groups the shape of the experimental curves on the upper part of the temperature range often differs essentially from that predicted by the Bayer theory. These deviations may be interpreted as due to the appearance of the considerable anharmonicity of the autonomous librations of the groups mentioned.     

Studies of the substituent effect in aromatic systems by 35 Cl-NQR. Chloroacetanilides ClxC6H5−x NHCOCH3−y Cly

The ³⁵Cl-NQR spectra of 45 chlorosubsitituted acetanilides, Cl_xC₆H_5?xNHCOCH_3?yCl_y, were investigated and the temperature dependence of some spectra, especially of monochloroacetic acid derivatives, was measured. A preliminary assignment of the NQR frequencies is given. A correlation between NQR frequencies and substituent parameters permits the study of the substituent effect of the acetamido group, ? NHCOCH_3?yCl_y. The chloro-substitution in the side chain of the acetanilides seems to have no noticeable influence on the ³⁵Cl-NQR frequencies of the chlorine atoms at the benzene ring. The NQR frequencies of the chlorine atoms in the chloroacetamido group are, on the other hand, insensitive to substitutions at the benzene nucleus. The possibility of steric influences on the NQR spectrum of ortho-chloro-substituted acetanilides is discussed. The investigation further confirms that a crystal field effect of about ±500 kHz must be considered in the interpretation of NQR spectra of chlorobenzene derivatives.     

Integrated absorption intensities of haloethanes and halopropanes

The infrared absorption intensities of the chlorofluorocarbons C₂Cl_xF_y, (x + y = 6); the hydrofluorocarbons C₂H_xF_yH (x + y = 6); and a number of hydrochlorofluorocarbons, including some members of the propane series, have been measured. Absorption intensities have been obtained by integration over specified ranges of frequencies. The ranges used include the atmospheric window (1250t-833 cm⁻¹), 3500-450 cm⁻¹, 1300-700 cm⁻¹, and those for selected individual absorption bands. Comparisons of the results have been made with published work where available, and attention is drawn to possible sources of error in the measurement of band areas. The spectra of the halopropanes have been included for the range 3500-150 cm⁻¹. A preliminary study has been made of the relation between the number of fluorine atoms in the molecule and the intensity of absorption of the CF stretching vibrations.     

Synthèse et propriétés magnétiques de solutions solides entre l'oxyde de chrome CrO2 et l'oxyhydroxyde de cobalt CoOOH

Solid solutions of general formula (1 ? x)CrO₂, xCoOOH have been prepared by hydrothermal synthesis under very high pressure conditions (80 kb). Cr⁶⁺O₃ and CoCr⁶⁺O₄ were used as starting materials. Homogeneous ferromagnetic phases were obtained when 0 ? x ? 0.5. X ray powder patterns clearly demonstrate the isotype with InOOH, an orthorhombic distorted rutile type structure. The results of the magnetic measures performed on samples with different compositions indicate that part of the Cr⁴⁺ cation have been reduced to Cr³⁺ and that the general formula of the solid solutions should be written Cr⁴⁺_1?(x+y)Cr³⁺_yCo²⁺_xO₂H_x+y.     

Nitrido-Sodalithe. I Synthese,Struktur und Eigenschaften von Zn7–xH2x[P12N24]Cl2 mit 0 ⩽ x ⩽ 3

Nitrido Sodalites. I Synthesis, Crystal Structure, and Properties of Zn_7–xH_2x [P₁₂N₂₄]Cl₂ with 0 ? x ? 3 The nitrido sodalites Zn_7–xH_2x[P₁₂N₂₄]Cl₂ with 0 ? x ? 3 are obtained by heterogeneous pressure-ammonolysis of P₃N₅ at presence of ZnCl₂ (T = 650°C). These compounds are available too by reaction of ZnCl₂, (PNCl₂)₃, and NH₄Cl at 700°C. The crystal structures of four representatives of the above mentioned compounds have been refined by the Rietveld full-profile technique using X-ray powder diffractometer data (I4 3m, a = 821.61(4) to 824.21(1) pm, Z = 1). In the solid a three-dimensional framework of corner-sharing PN₄-tetrahedra occurs (P? N: 163.6 pm, P? N? P: 125.6°, mean values) which is isosteric with the sodalite type of structure. In the center of the β-cages Cl^? ions have been found, which are tetrahedrally coordinated by Zn²⁺ ions. The Zn²⁺ ions are statistically disordered. According to the phase-width observed (0 ? x ? 3) the Zn²⁺ ions may be partially replaced each by two hydrogen atoms which on the other hand are covalently bonded to nitrogen atoms of the P? N framework. The IR-spectra of these compounds show characteristic vibrations.     

Hydrothermal synthesis, structure and property of nano-BaTiO3-based dielectric materials

A series of Ba_1-xSr_xTi_1-yZr_yO₃ (0≤x≤0.5, 0≤y≤0.4) and BA_1?xZn_xTi_1?ySn_yO₃ (0≤x≤0.3, 0≤y≤0.3) solid solutions were synthesized by low-temperature/low-pressure hydrothermal method below 170°C, 0.8 MPa. XRD pattern and cell parameters-composition figures of these prepared powders demonstrated that they are completely miscible solid solutions based on BaTiO₃. Furthermore, TEM showed that they have a shape of uniform, substantially spherical particles with an average particle size of 70 nm in diameter. The sintered ceramics of those powders doped by Sr²⁺ and Zr⁴⁺ or Zn²⁺ and Sn⁴⁺ have dielectric constant twelve times higher than and dielectric loss 1/6 those of pure BaTiO₃ phase at room temperature.     

Decorating Tetrathiafulvalene (TTF) with Fluorinated Phenyls through Sulfur Bridges: Facile Synthesis,Properties, and Aggregation through Fluorine Interactions

Tetrathiafulvalene derivatives ( TTF1 – TTF9 ) bearing fluorinated phenyl groups attached through the sulfur bridges have been synthesized by employing a copper‐mediated C–S coupling reaction of C₆H_5?xF_xI (x=1, 2, 5) and a zinc‐thiolate complex, (TBA)₂[Zn(DMIT)₂] (TBA=tetrabutyl ammonium, DMIT=1,3‐dithiole‐2‐thione‐4,5‐dithiolate), as the key step. Particularly, the selective synthesis of C₆F₅‐substituted ( TTF8 ) and C₆F₄‐fused ( TTF9 ) TTFs from C₆F₅I is disclosed. The physicochemical properties and crystal structures of these TTFs are fully investigated by UV/Vis absorption spectra, cyclic voltammetry, molecular orbital calculation, and single‐crystal X‐ray diffraction. The exchange of hydrogen versus fluorine on the peripheral phenyl groups show a notable influence on both the electronic and crystallographic natures of the resulting TTFs: 1) lowering both the HOMO and the LUMO energy levels, 2) modulating the electrochemical properties by regioselective and/or the degree of fluorination, 3) enhancing the driving forces of stacking by multiple fluorine interactions (F???S, C?F???π/π_F, C?F???F?C, and C?F???H). This work indicates that the decoration with fluorinated phenyls holds promise to produce functional TTFs with novel electronic and aggregation features.     

Fluorocarbon derivatives of nitrogen. Part 16 [1]. Synthesis of some unsymmetrical aromatic azo-compounds via diazotisation of fluorinated aryl- and -heteroaryl-amines in hydrofluoric or sulphuric acid [2]

Coupling reactions of the type Ar_FN⁺₂ + ArH → Ar_FN=NAr + H⁺ have been accomplished between fluorinated arenediazonium ions selected from the benzenic, pyridinic and pyrimidinic classes [Ar_F = C₆F₅, 4---CF₃C₆F₄, 4---C₅F₄N, 4z.sbnd;C₅F₃N.Cl---3, 4---C₅F₂N.Cl₂---3,5, 2---C₅F₃N.CF(CF₃)2---4, 4---C₄F₃N₂] and one or more aromatic compounds activated towards electrophilic attack (ArH = 1,3,5,---ME₃C₆H₃, 1,3,5---Et₃C₆H₃, MeOC₆H₆, and napth-2-ol). The diazonium ions were generated by addition of solid sodium nitrite to solutions of the amines Ar_FNH₂ in anhydrous hydrogen fluoride, 80% hydrofluoric acid, or 98% sulphuric acid mixed with glacial acetic acid and propionic acid. This work has established that perfluorinated arenediazonium ions rank amongst the most electrophilic species of their general class.     

Carbon-Fluorine Bondings of Fluorinated Fullerene and Graphite

Carbon-fluorine bondings of fluorinated fullerenes and fluorine-graphite intercalation compound C_xF were investigated in detail on the basis of XPS data and the potential model using the charge distribution calculated by semiempirical method. It has been confirmed by the present study that two peaks in the C_1s spectra observed for fluorinated fullerenes are assigned to carbon atoms bonded to fluorine atoms and those unbound to fluorine atoms, and the small difference in charges and Madelung potentials of fluorine atoms in different circumstances well explains the single peak in F_1s spectra of fluorinated fullerenes. In the calculated structures of 1,3-C₆₀F₂ and 1,2-C₆₀F_x (x = 2?6) used as the models of C_xF, three kinds of carbon-fluorine bondings were observed corresponding to nearly ionic, semicovalent and covalent C? F bondings. The calculated result supports that the bi-intercalation structure of stage 1 C_xF consists of nearly ionic and semi-covalent fluorines.     

Preparation and properties of stable mono-, tris-, tetrakis- or hexakis(pentahalophenyl)thalliate(III) complexes

Reaction of TlR₂X, TlX₃ and [TlX₄^? with RLi ( R = C₆F₅ or C₆Cl₅) leads to derivatives containing anions of the types [TlR₄]^?, [TlR₂R′₂]^? or [TlR₆]^3?. Reactions of TlCl₃ with [TlR₄]^? lead to [(μ-Cl)(TlR₂Cl)₂]^? (R = C₆F₅) or [TlRCl₃]^? (R = C₆Cl₅) while addition of X^? (X = Br^? or SCN^?) to Tl(C₆Cl₅)₃ gives [Tl- (C₆Cl₅)₃X]^?. All the novel anions were isolated as salts of bulky cations (Me₄N, Bu₄N, PPN or Ph₃BzP).     

Crystal structure refinements of the κ phases in the Hf-Mo-Se and Hf-Mo-Ge systems

The crystal structures of κ-(Hf-Mo-Se) and κ-(Hf-Mo-Ge) were determined using X-ray single-crystal diffractometry. Both structures crystallize in the space groupP6₃/mmc (No. 194) with the unit-cell dimensionsa = 8.6995(4)A?,c = 8.6234(7)A? for κ-(Hf-Mo-Se) anda = 8.6394(4)A?,c = 8.6827(5)A? for κ-(Hf-Mo-Ge). The structures have been refined onF² toR(F²) values of 0.0784 and 0.0661, respectively. κ-(Hf-Mo-Se) and κ-(Hf-Mo-Ge) are isostructural with κ-(Hf-Mo-P) with a variable degree of hafnium substitution on the molybdenum sites of the structure. In κ-(Hf-Mo-Ge) germanium vacancies were found to occur on the trigonal prismatic 2c site and the phase was also found to contain oxygen on the octahedral 6g site. According to the final refinements the compositions are Hf_9+xMo_4?xSe withx = 0.40(2) and Hf_9+xMo_4?xGe_yO₂ withx = 0.25(2),y = 0.88(1), andz = 1.47(12).     

Bildung und NMR-spektroskopische Charakterisierung von Alk-(ar-)oxyderivaten von Trichlorphosphazen-N-phosphoryldichlorid,Cl3PN?P(O)Cl2, Imido- und N-Methylimidodiphosphoryltetrachlord,Cl2P(O)NHP(O)Cl2 bzw. Cl2P(O)N(CH3)P(O)Cl2

Formation and N.M.R.-Spectroscopic Characterization of Alk-(ar-)oxy Derivatives of Trichlorophosphazene-N-phosphoryldichloride, Cl₃P?N? P(O)Cl₂, Imido- and N-Methylimidodiphosphoryltetrachloride, Cl₂P(O)NHP(O)Cl₂ and Cl₂P(O)N(CH₃)P(O)Cl₂ The ester chlorides and esters P₂NOCl_5?x(OR)_x (x = 1?5), P₂(NH)O₂Cl_4?x(OR)_x (x = 1–4) and P₂(NCH₃)O₂Cl_4–x(OR)_x (x = 1–4) derived from the title compounds by substitution of chlorine atoms by alk- or aroxy groups are characterized by their ³¹P-n.m.r. data. The possibilities for forming these compounds by alcoholysis, chloridolysis, dealkylation and P? N-bond formation are discussed.     

Nitrido-Sodalithe. II. Synthese,Struktur und Eigenschaften von M(6+(y/2)–x)H2x[P12N24]Zy mit M = Fe,Co, Ni,Mn; Z = Cl,Br, I; 0 ≤ x ≤ 4; y ≤ 2

Nitrido-Sodalites. II. Synthesis, Crystal Structure, and Properties of M_{(6+(y/2)–x)}H_2x[P₁₂N₂₄]Z_y with M = Fe, Co, Ni, Mn; Z = Cl, Br, I; 0 ≤ x ≤ 4; y ≤ 2 The nitrido sodalites M_{(6+(y/2)–x)}H_2x[P₁₂N₂₄]Z_y with M = Fe, Co, Ni, Mn; Z = Cl, Br, I; 0 ≤ x ≤ 4; y ≤ 2 are obtained by the reaction of HPN₂ or [PN(NH₂)₂]₃ with the metal halogenide MZ₂ (T = 700°C). The compounds are isotypic to Zn_(7–x)H_2x[P₁₂N₂₄]Cl₂. An increase of the ionic radii of the cations or anions results in an expansion of the lattice which is caused by an increase of the P? N? P angle. The influence of the cation is more dominant than that of the anion. By reacting [PN(NH₂)₂]₃ with metal halogenide (MZ₂) hydrogen free, X-ray amorphous products are obtained. The formation of the chloride-containing P? N-sodalite in this reaction begins at temperatures below 450°C.     

Vacuum ultraviolet laser‐induced fluorescence kinetic study of the reactions of Cl atoms with fluoroalkenes (CxF2x+1CHCH2, x = 1,2,4, 6, and 8) at low pressures

Pulsed laser photolysis/vacuum ultraviolet laser‐induced fluorescence techniques were used to measure rate coefficients for Cl atom reactions with a series of fluoroalkenes (C_xF_2x+1CH?CH₂, x = 1,2,4,6,8) in 6–10 Torr of CF₄ diluent at 295 ± 2 K. Rate coefficients (units of 10^?11 cm³ molecule^?1s^?1) of 4.49 ± 0.64, 6.58 ± 0.59, 8.91 ± 0.58, 9.27 ± 0.64, and 9.00 ± 0.87 were determined for C_xF_2x+1CH?CH₂ with x = 1,2,4,6, and 8, respectively. In 6–10 Torr of CF₄ diluent, the kinetics of the title reactions are at, or near, the high‐pressure limit for x = 4, 6, and 8, approximately 30% below the high‐pressure limit for x = 2, and approximately 50% below the high‐pressure limit for x = 1. © 2007 Wiley Periodicals, Inc. Int J Chem Kinet 39: 328–332, 2007     

Herstellung von fluorreichen Verbindungen der Reihe C2ClnF6−n in heterogener Katalyse

Preparation of Compounds of the Series C₂Cl_nF_6?n with High Fluor Contents by Heterogeneous Catalysis A survey is given on catalytic systems for Cl? F exchange reactions with C₂Cl₆. A catalyst is described which is formed by reaction of C₂Cl₄/Cl₂/HF on γ-Al₂O₃ in Ni reactors. Deposition of nickel proceeds by the reaction Ni(CO)₄ → Ni + 4 CO. The formation of the catalyst and the catalytic reactions which give highly fluorinated C? Cl? F compounds are discussed.     

The first chlorofluoride in niobium cluster chemistry structure of the double salt: NaxNb7F21−yCly (x ~ 2; y ~ 8)

The new compound Na_xNb₇F_{21 − y}Cl_y (x ~ 2 ; y ~ 8) synthesized by solid state chemistry crystallizes in the cubic system (space group Pm-3m) with a = 8.2005 (9) Å. The structure has been determined by X-ray diffraction on single crystal; it is related to that of Nb₆F₁₅. However, in the title compound, only one Nb₆Fⁱ_{poststaggered12}F^a-a_{poststaggered6/2} subnetwork is preserved. The second one is replaced by (NbFe)ⁿ⁻ entities. Additional Na⁺ cations provide the cohesion of the structure. We present here this new structure and discuss the possible oxidation states of the single niobium atom inside the (NbF₆)ⁿ⁻ entities and the valency electron concentration (VEC) of the Nb₆ cluster.     

Sur de nouveaux ferrites oxyfluorés d'yttrium ou de gadolinium à structure grenat

The oxyfluoride garnets of formula Y₃Fe_5?xM_xO_12?xF_x and Gd₃Fe_5?xM_xO_12?xF_x (M = 3d transition element) result from partial substitution of O^2? by F^? in Y₃Fe₅O₁₂ and Gd₃Fe₅O₁₂ oxides. The cationic charge compensation is obtained by replacing the Fe³⁺ ions by divalent ions as Mn²⁺, Co²⁺, Ni²⁺, Cu²⁺ or Zn²⁺ ions. The site occupied by some of these ions (Mn²⁺, Ni²⁺, Zn²⁺) is determined by magnetic or Mössbauer measurements.     

Interaction of pentafluoropyridine with 4-nitrophenol and pentafluorophenol in the presence of potassium fluoride and 18-crown-6-ether

The reactions of 4-nitro- and pentafluorophenols with C₅F₅N, 4-ArOC₅F₄N and 2,4-(ArO)₂C₅F₃N (Ar = 4-NO₂C₆H₄, C₆F₅) in the presence of KF and catalitic amounts of 18-crown-6- -ether at various temperatures have been investigated. The leaving ability of the C₆F₅O-group is shown to be higher than that of the 4-NO₂C₆H₄O-group in the reactions of 4-ArOC₅F₄N, 2,4-(ArO)₂C₅F₃N and 2,4,6-(ArO)₃C₅F₂N with F^?-anion, which is in agreement with the order of the basicity of anions (C₆F₅O^?<4-NO₂C₆H₄O^?). The reaction pathways of pentafluoropyridine with ArO^?-anions are discussed.