Chalkogenfluoride in niedrigen Oxydationsstufen. V. Die ungewöhnlichen chemischen Gleichgewichte F3S?SF ⇌ 2SF2 und CF3SF2?SCF3 ⇌ 2 CF3SF

Lower Chalcogen Fluorides V. Unusual Chemical Equilibria F₃S? SF ? 2 SF₂ and CF₃SF₂? SCF₃ ? 2 CF₃SF SF₂ and CF₃SF form unusual chemical equilibria with their dimers F₃SSF and CF₃SF₂ SCF₃ involving two different bonds (SF and SS). The equilibrium between F₃SSF and SF₂ is disturbed by a decomposition reaction of these compounds yielding SF₄ and SSF₂ · K_p (298) = 2.5 · 10^?3atm, ΔH°₂₉₈ = 68.5 kJ/mol for the system F₃SSF ? 2SF₂ and K_p(298) = 1.3 × 10³ atm, δH₂₉₈ = 42.5 kJ/mol for the system CF₃SF₂SCF₃ ? 2CF₃SF have been determined as the equilibrium constants and the dissociation enthalpies. In both systems kinetic hindrance delays the achievement of the equilibrium. The rates for dissociation and decomposition are strongly surface dependent. Under favourable conditions the half-lives at 298 K for the dissociation of F₃SSF and CF₃SF₂SCF₃ are found to be ca. 8 h and ca. 2 h respectively, and for the decomposition of SF₂ and CF₃SF (p ～ 13 mbar) the values are ca. 10 h and 1 year respectively.     

The unusual chemical equilibria F3SSF ⇌ 2 SF2 and CF3SF2SCF3 ⇌ 2CF3SF

In order to understand more about the instability of sulfur difluoride, we have investigated the chemical interrelations between each of the monomers SF₂ and CF₃SF and the corresponding dimers F₃SSF and CF₃SF₂SCF₃. Thus we have found that SF₂ and CF₃SF exist in chemical equilibria with their dimers. These equilibria are unusual because they involve two different bonds (SF and SS). The equilibrium constants and dissociatíon enthalpies have been determined by i.r. and mass spectroscopic measurements.

The equilibrium between F₃SSF and SF₂ is disturbed by a decomposition reaction of these compounds yielding SF₄ and SSF₂. In both systems (1) and (2) the achievement of the equilibrium is comparatively slow at ?30 to 30 °C. The rates for dissociation and decomposition are strongly surface-dependent and the kinetics of the two processes have been studied separately. Under favorable conditions the half-lives at 298 K for the dissociation of F₃SSF and CF₃SF₂SCF₃ are found to be ca. 8.h and ca. 2 h, respectively, and for the decomposition of SF₂ to SF₄ and SSF₂ and CF₃SF to CF₃SF₃ and CF₃SSCF₃ (p?13 mbar) the values are ca. 10 h and 1 year respectively.     

Bis(trifluoromethyl)fluorsulfonium(IV)-metallate(V) [1] (CF3)2SF+MF6- (M = As,Sb)

The preparation of (CF₃)₂SF⁺MF₆^- (M = As, Sb) is reported. New salts have been synthesized from the reaction of (CF₃)₂SF₂ with strong Lewis acids and CF₃SCF₃ with XeF⁺MF₆^- (M = As, Sb). They are characterised by Raman- and NMR - spectroscopy.     

Umsetzungen von Thiazylhalogeniden XSN (X = F,Cl) mit perfluorierten Iminen Rf2NH (Rf = F,CF3, CF3S, (CF3)2C, (CF3)2 S): Versuche zur Darstellung von Aminothiazylen (N?SN)

Reactions of Thiazyl Halides XSN (X = F, Cl) with Perfluorinated Imines R_f2 NH (R_f = F, CF₃, CF₃S, (CF₃)₂C?, (CF₃)₂S?): Attempted Preparations of Aminothiazyls (?N? S?N) Thiazyl halides or their precursors Cl₃S₃N₃ and FC(O)N?SF₂ react with perfluoro imines to provide the corresponding aminothiazyls as unstable and reactive intermediates. While with HNF₂ or KF · HNF₂ the final products N₂F₄ and S₄N₄ are formed, [(CF₃)₂N]₂Hg reacts with Cl₃S₃N₃ to give CF₃N?CF₂, FSN, and HgCl₂. The expected product CF₃SN?S?NSCF₃ ( 4 ) is obtained from (CF₃S)₂NH or Hg[N(SCF₃)₂]₂ and FSN probably via (CF₃S)₂ NSN. Surprisingly, (CF₃)₂C?NLi forms with ClSN, Cl₃S₃N₃ or [S₃N₂Cl]Cl in the presence of NH₄Cl 4,5-Dihydro-3,3,5,5-tetrakistrifluoromethyl-3H-1λ⁴,2,4,6-thiatriazine ( 6 ) and (CF₃)₂C?NS_xN?C(CF₃)₂ (X = 1, 2) ( 7a, b ) as byproducts. A CsF catalyzed reaction at 70 to 80°C between (CF₃)₂C?NLi and FSN provides low yields of (CF₃)₂C?N? S? N?S?NCF(CF₃)₂ ( 8 ) together with 7a, b. The latter are the only products without CsF. When (CF₃)₂S?NH is treated with FSN, the compounds CF₃SCF₃, S₄N₄, and N₂ are identified. It is shown by ¹⁹F and ¹⁴N-n.m.r. spectroscopy that (CF₃)S?NSN is an unstable intermediate.     

Novel ammonium hexafluoroarsenate salts from reaction of (CF3)2NH,CF3N(OCF3)H,CF3N[OCF(CF3)2]H,CF3NHF and SF5NHF with the strong acid HF/ASF5.

Reactions of the fluorinated amines (CF₃)₂NH, CF₃N(OCF₃)H, CF₃N[OCF(CF₃)₂]H, CF₃NHF and SF₅NHF with the strong acid HF/AsF₅ form the corresponding ammonium salts R_f¹R_f²NH₂⁺AsF₆^? and R_fNFH₂⁺ AsF₆^? in high yield. [R_f¹=CF₃, R_f²=CF₃, CF₃O, (CF₃)₂CFO; R_f=CF₃, SF₅] The colorless crystalline solids are stable for prolonged periods at 22°C in sealed FEP containers. They have dissociation pressures at 22°C ranging from ～5 torr (R_fNFH₂⁺ AsF₆^?) to ～50 torr [CF₃N(OCF₃)H₂⁺AsF₆^?]. ¹⁹F NMR and Raman spectroscopy were used to identify the compounds.     

Reaktionen von Sulfensäurefluoriden: Synthese,Charakterisierung und NMR-Studien von Perhalogenalkylmercaptotetrafluorphosphoranen

Reactions of Sulfenic Fluorides: Synthesis, Characterization and N.M.R. Studies of Perhalogenalkylmercaptotetrafluorphosphoranes Marcaptotetrafluorophosphoranes R_fSPF₄ (R_f = CF₃, CF₂Cl) are obtained by the reaction of sulfenic fluorides R_fSF with PF₃. The compounds formed are extremely sensitive to hydrolysis. They react with H₂O yielding R_fSH, HF and POF₃ as well as with an excess of R_fSF to give PF₅ and R_fSSR_f. NMR studies were performed at various temperatures.     

Synthese und Eigenschaften von Diethyldithiocarbaminsäureperfluororganylestern, (C2H5)2NC(S)SRf (Rf = CF3, C2F5, i‐C3F7, n‐C4F9, C6F5)

Syntheses and Properties of Perfluoroorgano Esters of the Diethyldithiocarbamic Acid, (C₂H₅)₂NC(S)SR_f (R_f = CF₃, C₂F₅, i‐C₃F₇, n‐C₄F₉, C₆F₅) Tetraethylthiuram disulfide reacts under different conditions with perfluoroorgano silver(I), AgR_f, and perfluoroorgano cadmium compounds, Cd(R_f)₂, to give the corresponding perfluoroorgano esters of diethyldithiocarbamic acid, (C₂H₅)₂NC(S)SR_f (R_f = CF₃, C₂F₅, i‐C₃F₇, n‐C₄F₉, C₆F₅), and metal diethyldithiocarbamates, AgSC(S)N(C₂H₅)₂ and Cd[SC(S)N(C₂H₅)₂]₂. The mechanisms of the reactions with AgR_f and Cd(R_f)₂ are discussed.     

Darstellung und spektroskopische Charakterisierung der Persulfoniumsalze (CH3)(CF3)SF3+SbF6− und (CH3)(CF3)2SF2+SbF6− und Kristallstruktur von CF3SF2+SbF6−

Preparation and Spectroscopic Characterization of the Persulfonium Salts (CH₃)(CF₃)SF₃⁺SbF₆^? and (CH₃)(CF₃)₂SF₂⁺SbF₆^? and Crystal Structure of CF₃SF₂⁺SbF₆^? [1] . The preparation of the persulfonium salts (CH₃)(CF₃)SF₃⁺SbF₆^? and (CH₃)(CF₃)₂SF₂⁺SbF₆^? by methylation of the sulfuranes CF₃SF₃ and (CF₃)₂SF₂ with CH₃OSO⁺SbF₆^? in liquid SO₂ is reported. The thermolabile compounds are characterized by IR, Raman, ¹H, ¹³C, and ¹⁹F NMR spectroscopy. CF₃SF₂⁺SbF₆^? crystallizes in the space group C2/c with a=16.889(8) Å, b=7.261(4) Å, c=13.416(7) Å, β=91.08° with 8 formula units per unit cell at 167 K. Cations and anions are connected via short SF contacts forming a Ψ-octahedral surrounding of the central S atom which is in close analogy to the already known CF₃SF₂⁺AsF₆^?.     

Fluorination of perfluoroalkylsulfenyl chlorides,perfluorodialkyl disulfides and perfluorodialkyl sulfides with chlorine monofluoride

In reactions with perfluoroalkylsulfenyl chlorides (R_fSCl; R_f = F₃, C₂F₅, n-C₃F₇, n-C₄F₉) and perfluoroalkyl disulfides (R_fSSR_f′; R_f = R_f′ = CF₃, R_f = CF₃, R_f′ = C₂F₅) at 25°, chlorine monofluoride acts primarily as a chlorinating and fluorinating reagent to give the corresponding perfluoroalkylsulfur chloride tetrafluorides, R_fSF₄Cl, in good yields. However, small amounts of perfluoroalkylsulfur pentafluorides, R_fSF₅, are also obtained. A mixture of the cis and trans isomers of bis(trifluoromethyl)sulfur tetrafluoride and of trifluoromethyl pentafluoroethylsulfur tetrafluoride has been formed by the reaction of the corresponding bis(perfluoroalkyl) sulfides and chlorine monofluoride. The new perfluoroalkylsulfur chloride tetrafluorides are colorless, unpleasant smelling liquids. The infrared, mass and ¹⁹F NMR spectral data, as well as thermodynamic and elementary analysis data, are given for the new compounds.     

Solvents effects in reactions between perfluoroalkyliodides and cadmium

The interaction between perfluoroorgano iodides (R_fI where R_f = F(CF₃)₂C(CF₂CF₂)₃, n-C₆F₁₃,n-C₈F₁₇, F(CF₃)₂COCF₂CF₂,F(CF₃)₂CO(CF₂CF₂)₄ andC₂H₅OC(O)(CF₂CF₂) with cadmium in an acetonitrilesolvent media produces primarily the coupled products (R_fR_f,72–90% yield) in addition to minor quantities of the reduction products (R_fH). On the other hand ICF₂CF₂I and C1CF₂CFC1I, by a 1,2-dehalogenation reaction, form the olefins CF₂ = CF₂ and CF₂ = CFC1, respectively, as the principal products. The interaction of R_fI compounds with cadmium in other solvent media, e.g. diethyl ether. tetrahydrofuran (THF), N,N-dimethylformamide (DMF), and bis(2-methoxyethyl)ether(diglyme) were examined and found to produce a different ratio of R_fR_f and R_fH products. {ft*}Present address: Fluidics Inc., P.O.Box 1886, Dayton, OH 45429 U.S.A.     

Synthesen und Eigenschaften von Tetrakis(perfluoralkyl)tellur Te(Rf)4 (Rf = CF3, C2F5, C2F5, C3F7, C4F9)

Synthesis and Properties of Tetrakis(Perfluoroalkyl)Tellurium Te(R_f)₄ (R_f = CF₃, C₂F₅, C₃F₇, C₄F₉) Te(CF₃)₄ is obtained from the reaction of Te(CF₃)Cl₂ with Cd(CF₃)₂ complexes as a complex with e. g. CH₃CN, DMF. It is a light and temperature sensitive hydrolysable liquid. The reaction with fluorides yields the complex anion [Te(CF₃)₄F]⁻, with fluoride ion acceptors the complex cation [Te(CF₃)₃]⁺. With traces of water an acidic solution is formed. Te(CF₃)₄ acts as a trifluoromethylation reagent. The reaction with XeF₂ gives hints for the formation of Ye(CF₃)₄F₂. Properties and NMR spectra are discussed. The much more stable complexes of Te(R_f)₄ (R_f = C₂F₅, C₃F₇, C₄F₉) are formed from the reaction of TeCl₄ with the corresponding Cd(R_f)₂ complexes.     

Koordinationsverbindungen des Silber(I) mit stickstoffhaltigen Liganden Kristallstruktur des NC?SCF2CF2S?CN

Coordination Compounds of Silver(I) with Nitrogen-Containing Ligands. Crystal Structure of NC? SCF₂CF₂S? CN The reaction of F₂S?NCN and NC? SCF₂CF₂S? CN with AgAsF₆ leads to the coordination compounds (F₂S?NCN)₂AgAsF₆ 2 and (NC? SCF₂CF₂S? CN)₂AgAsF₆ 5 . NC? SCF₂CF₂S? CN 3 is formed by the reaction of ClSCF₂CF₂SCl with HCN as well as with Me₃SiCN. 4 is a by-product of the reaction with HCN. 4 was characterized as a six-membered heterocycle. 3 was investigated by an X-ray single structure analysis. In the solid state the all-trans form was found.     

Preparation of 2-chloro-3-pentafluorosulfur tetrafluoropropylene, and its use in telomerization reactions

The synthesis of a new SF monomer, 2-chloro-3-pentafluorosulfur tetrafluoropropylene, SF₅CF₂C(Cl)=CF₂. is reported.We wish to report the synthesis of a new SF monomer, 2-chloro-3-pentafluorosulfur tetrafluoropropylene, SF₅CF₂C(Cl)=CF₂. The synthesis involves the following sequence of reactions:

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The preparation of (I), 1,2-dibromo-1,1,3,3-tetrafluoropropane, was carried out according to the method of Tarrant et al [1]. The preparation of (II), tetrafluoroallene (TFA), was essentially that of Muehlner [2] with slight modification. We were able to obtain consistent yields of about 70% using a larger excess of KOH with an efficient ice condenser. The reactor was heated slowly and held at about 90°C with a nitrogen sweep to remove TFA as it was formed. The preparation of (III), 2-chloro-3-pentafluorosulfur tetrafluoropropylene was carried out in a metal bomb at 90–100°C for 1 to 16 hours with a yield of 20 percent.     

Direct synthesis of fluorinated peroxides. 9. Some reactions of perfluorotertiarybutyl hydroperoxide.

The reaction of (CF₃)₃COOH with perfluoroacyl fluorides in the pressure of NaF results in the formation of new peroxy esters of the type, (CF₃)₃COOC(O)R_f. Addition of the hydroperoxide to CF₃NCF₂ yields the unstable amine (CF₃)₃COOCF₂N(H)CF₃. These reactions of (CF₃)₃COOH are compared with analogous reactions of CF₃OOH and SF₅OOH.     

Branching ratios for BrO production from reactions of O(1D) with HBr,CF3Br,CH3Br,CF2ClBr,and CF2HBr

Laser-flash photolysis of RBr/O₃/SF₆/He mixtures at 248 nm has been coupled with BrO detection by time-resolved UV absorption spectroscopy to measure BrO product yields from O(¹D) reactions with HBr, CF₃Br, CH₃Br, CF₂ClBr, and CF₂HBr at 298±3 K. The measured yields are: HBr, 0.20±0.04; CF₃Br, 0.49±0.07; CH₃Br, 0.44±0.05; CF₂ClBr, 0.31±0.06; and CF₂HBr, 0.39±0.07 (uncertainties are 2σ and include estimates of both random and systematic errors). The results are discussed in light of other available information or O(¹D)+RBr reactions. © 1998 John Wiley & Sons, Inc. Int J Chem Kinet 30: 555–563, 1998     

The reaction of XeF+MF6− (M = As,Sb) with sulfuranes; preparation of CF3(O)F2+SbF6− and (CF3)2SOXeF+SbF6−

CF₃S(O)F, (CF₃)₂SO, CF₃SF₃, (CF₃)₂SF₂, and SF₄ react in different manner with XeF⁺MF₆^? (M?As, Sb). An oxidative fluorination is observed by CF₃S(O)F forming the persulfonium salt CF₃S(O)F₂⁺SbF₆^?, whereas by (CF₃)₂SO a simple addition product containing xenon can be isolated in form of the sulfonium salt (CF₃)₂SOXeF⁺SbF₆^?. On the contrary, the Lewis-acidic character of the XeF⁺-cation predominates against (CF₃)_nSF_4?n (n = 0 ? 2) leading to the corresponding fluorosulfonium salts (CF₃)_nSF_3?n ⁺MF₆^? (M?As, Sb) and XeF₂.     

Synthese und Kristallstrukturen von monomeren bis(thiophenolato)metall(II)-Komplexen

Preparation and Structures of Monomeric Bis(thiophenolato)metal(II) Complexes Sodium-2,4,6-tris(trifluoromethyl)thiophenolate (NaSR_f) reacts with MCl₂ (M = Zn, Pb) in the molar ratio of 2:1 to form the bis(thiophenolato)metal(II)complexes bis[2,4,6-tris(trifluoromethyl)thiophenolato]zinc 1 and bis[2,4,6-tris(trifluoromethyl)thiophenolato]lead 2 . Reaction of Mn[N(SiMe₃)₂]₂· THF with two equivalents of 2,4,6-tris(trifluoromethyl)thiophenol (R_fSH) forms Mn(SR_f)₂ · THF 3 . All compounds crystallize as THF adducts. The structures of Zn(SR_f)₂ · 2THF 1a , Pb(SR_f)₂ · THF 2a and Mn(SR_f)₂ · 2THF 3a are discussed.     

Absolute rate constants for the self reactions of HO2, CF3CFHO2, and CF3O2 radicals and the cross reactions of HO2 with FO2, HO2 with CF3CFHO2, and HO2 with CF3O2 at 295 K

The kinetics of the self-reactions of HO₂, CF₃CFHO₂, and CF₃O₂ radicals and the cross reactions of HO₂ with FO₂, HO₂ with CF₃CFHO₂, and HO₂ with CF₃O₂ radicals, were studied by pulse radiolysis combined with time resolved UV absorption spectroscopy at 295 K. The rate constants for these reactions were obtained by computer simulation of absorption transients monitored at 220, 230, and 240 nm. The following rate constants were obtained at 295 K and 1000 mbar total pressure of SF₆ (unit: 10⁻¹² cm³ molecule⁻¹ s⁻¹): k(HO₂+HO₂)=3.5±1.0, k(CF₃CFHO₂+CF₃CFHO₂)=3.5±0.8, k(CF₃O₂+CF₃O₂)=2.25±0.30, k(HO₂+FO₂)=9±4, k(CF₃CFHO₂+HO₂)=5.0±1.5, and k(CF₃O₂+HO₂)=4.0±2.0. In addition, the decomposition rate of CF₃CFHO radicals was estimated to be (0.2–2)×10³ s⁻¹ in 1000 mbar of SF₆. Results are discussed in the context of the atmospheric chemistry of hydrofluorocarbons. © 1997 John Wiley & Sons, Inc.     

Bis(dimethylamino)trifluoromethylsulfonium Salze: [CF3S(NMe2)2]+[Me3SiF2]‐, [CF3S(NMe2)2]+[HF2]‐ und [CF3S(NMe2)2]+[CF3S]‐

Bis(dimethylamino)trifluoro sulfonium Salts: [CF₃S(NMe₂)₂]⁺[Me₃SiF₂]^‐, [CF₃S(NMe₂)₂]⁺ [HF₂]^‐ and [CF₃S(NMe₂)₂]⁺[CF₃S]^‐ From the reaction of CF₃SF₃ with an excess of Me₂NSiMe₃ [CF₃(NMe₂)₂]⁺[Me₃SiF₂]^‐ (CF₃‐BAS‐fluoride) ( 5 ), from CF₃SF₃/CF₃SSCF₃ and Me₂NSiMe₃ [CF₃S(NMe₂)₂]⁺‐ [CF₃S]^‐ ( 7 ) are isolated. Thermal decomposition of 5 gives [CF₃S(NMe₂)₂]⁺ [HF₂]^‐ ( 6 ). Reaction pathways are discussed, the structures of 5 ‐ 7 are reported.     

Atmospheric chemistry of HFC-134a: Kinetics of the decomposition of the alkoxy radical CF3CFHO

Decomposition of the CF₃CFHO radical formed in the reaction of CF₃CFHO₂ radicals with NO was studied at 296 and 393 K using a pulse radiolysis transient VIS-UV absorption absolute rate technique. At room temperature in 1 atmosphere of SF₆ diluent it was found that the majority (79 ± 20)% of CF₃CFHO radicals formed in the CF₃CFHO₂ + NO reaction decompose within 3 μs via C(SINGLE BOND)C bond scission. This result is discussed with respect to the current understanding of the atmospheric degradation of HFC-134a. As a part of the present work the rate constant ratio k_CF3CFH+02/k_CF3CFH+NO was determined to be 0.144 ± 0.029 in one atmosphere of SF₆ diluent at 296 K. © 1997 John Wiley & Sons, Inc. Int J Chem Kinet 29: 209–217, 1997.