Electrochemical study of the methylcyclopentane oxidation in anhydrous hydrogen fluoride and HF−SbF5 superacid solutions

The electrochemical study of methylcyclopentane (MCPH) oxidation in anhydrous hydrogen fluoride and related superacid media leads to determination of the standard potentials of the MCPH redox couples and to the establishment of the potential acidity diagram of MCPH. Fromtthese results the oxidation by H⁺ ion of MCPH into the carbenium ion MCP⁺ is observed in acidic media: pH<6 or R(H)<?21.9 (pH values are reported on the acidity scale in HF, pH=0 for a molar solution of SbF₅, and the acidity levels are referred to H₂O by means of an R(H) function: for pH=0, R(H) is ?27.9). In HF?SbF₅ mixtures, pH<2.3 or R(H) <?25.6, the protonation of MCPH to form the carbonium ion MCPH₂⁺ has to be taken into account and the acidity constant is determined. In basic media, pH>8.1 or R(H)>?19.8, condensation reactions are enhanced through a radical oxidation state; the disproportionation constant of the dimer (MCP)₂ is determined. Moreover, in the most acidic media, pH<2 or R(H)<?25.9, evidence for the cracking of MCPH through the protolysis of a C?C bond is shown.     

Protonation of Nitramines: Where Does the Proton Go?

The reactions of nitramine, N ‐methyl nitramine, and N ,N ‐dimethyl nitramine with anhydrous HF and the superacids HF/MF₅ (M=As, Sb) were investigated at temperatures below −40 °C. In solution, exclusive O‐protonation was observed by multinuclear NMR spectroscopy. Whereas no solid product could be isolated from the neat HF solutions even at −78 °C, in the HF/MF₅ systems, protonated nitramine MF₆⁻ salts were isolated for the first time as moisture‐sensitive solids that decompose at temperatures above −40 °C. In the solid state, depending on the counterion, O‐protonated or N‐protonated cations can be formed, in accord with theoretical calculations which show that the energy differences between O‐protonation and N‐protonation are very small. The salts [H₂N‐NO₂H][AsF₆], [H₃N‐NO₂][SbF₆], [MeHNNO₂H][SbF₆], and [Me₂NNO₂H][SbF₆] were characterized by their X‐ray crystal structures.     

The preparation and 119Sn mössbauer spectra of [Sn2F3] [MF6] (M  As,Sb)

Tin(II) fluoride reacts with Lewis acids, AsF₅ and SbF₅, in a 2:1 ratio, to give salts of the [Sn₂F₃⁺] cation. Reaction of SnF·MF₆ with SnF₂ in liquid SO₂ also produces the [Sn₂F₃] [MF₆] salt. Tin-119 Mössbauer data are presented and compared with those for SnF₂, SnF·MF₆ and Sn(SbF₆)₂.     

Über die Kristallstrukturen von CH3PF2H+AsF6− und CH3PF2H+SbF6− und eine einfache Darstellung von CH3PF2

On the Crystal Structures of CH₃PF₂H⁺AsF₆^? and CH₃PF₂H⁺SbF₆^? and a simple Method for Preparation of CH₃PF₂ A simple method for preparation of CH₃PF₂ from CH₃PCl₂ is reported. The phosphonium salts CH₃PF₂H⁺MF₆^? are obtained by the reaction of CH₃PCl₂ with superacidic systems HF/MF₅ (M = As, Sb). CH₃PF₂H⁺SbF₆^? crystallizes in the space group P1 with a = 548.4(4) pm, b = 695.5(8) pm, c = 960.2(9) pm, α = 94.68(5)°, β = 97.19(6)°, γ = 94.41(6)° and Z = 2. CH₃PF₂H⁺SbF₆^? crystallizes in P1 with a = 554.3(3), b = 724.2(4), c = 970.4(5), α = 94.73(4)°, β = 96.14(5)°, γ = 95.30(4)°.     

Bromsulfenyl(trihalogen)phosphonium-Salze Cl3−nBrnPSBr+AsF6− (n = 0 – 3) und Cl3PSBr+SbF6− — Oxidative Bromierung von Thiophosphorylhalogeniden

Bromosulfenyl(trihalogeno)phosphonium Salts Cl_3?nBr_nPSBr⁺AsF₆^? (n = 0 – 3) and Cl₃PSBr⁺SbF₆^? — Oxidative Bromination of Thiophosphorylhalides The bromosulfenyl(trihalogeno)phosphonium salts Cl_3?nBr_nPSBr⁺AsF₆^? (n = 0 – 3) and Cl₃PSBr⁺SbF₆^? are prepared by oxidative bromination of the corresponding thiophosphorylhalides with Br₂/MF₅ (M = As, Sb) and characterized by vibrational and NMR spectroscopy.     

Methyloxoniumhexafluorometallate – Synthese,spektroskopische Charakterisierung sowie die Kristallstruktur von H3COH2+AsF6–

Methyloxoniumhexafluorometallates – Synthesis, Spectroscopic Characterization and Crystal Structure of H₃COH₂⁺AsF₆^– Up to now the protonation of methanol as a hydrogen bridged dimethanolium ion [H(CH₃OH)₂]⁺ was observed by different X-ray crystal structure studies. Now the preparation of H₃COH₂⁺MF₆^– in super acid media HF/MF₅ (M = As, Sb) is reported. The thermolabile and moisture sensitive salts are characterized by vibrational and NMR spectroscopy. H₃COH₂⁺AsF₆^– crystallizes in the monoclinic space group P2₁/m (No. 11) with a = 487.8(1), b = 714.0(2), c = 848.2(2) pm, β = 98.03°(2) with 2 formula units per unit cell.     

Darstellung von Dichlornitronium-hexafluoroarsenat und -hexafluoroantimonat ONCl2+MF6−(M = As,Sb)

Preparation of Dichlornitronium-hexafluoroarsenate and -hexafluoroantimonate ONCl₂⁺MF₆^?(M = As, Sb) The preparation of ONCl₂⁺MF₆^? (M = As, Sb) by oxidative chlorination of CNCl with Cl₂/AsF₅ and Cl₂/SbF₅ is reported. Both salts are characterized by Raman Spectroscopy. The difficulties in evaluating a force field for the cation are discussed.     

Über die Darstellung der Pnikogenoniumsalze AsH4+SbF6−, AsH4+AsF6−, SbH4+SbF6−

On the Preparation of Pnikogenonium Salts AsH₄⁺SbF₆^?, AsH₄⁺AsF₆^?, SbH₄⁺SbF₆^? The preparation of the pnikogenonium salts AsH₄⁺SbF₆^?, AsH₄⁺AsF₆^? and SbH₄⁺SbF₆^? by protonation from the hydrides AsH₃, SbH₃ in superacidic systems HF/SbF₅ and HF/AsF₅, resp. is reported. The salts are characterized by vibrational and mass spectra. A general valence force field is calculated. The following onium ions are know as hexafluoroantimonate:      

Protonated MF3 (M = N-Bi): Structure, stability, and thermochemistry of the H-MF3 and HF-MF2 isomers

The structure, stability, and thermochemistry of the H(MF₃)⁺ isomers (M = N-Bi) have been investigated by MP2 and coupled cluster calculations. All the HF-MF₂⁺ revealed weakly bound ion-dipole complexes between MF₂⁺ and HF. For M = N, As, Sb, and Bi they are more stable than the H-MF₃⁺ covalent structures (free energy differences) by 6.3, 14.3, 32.1, and 73.5 kcal mol⁻¹, respectively. H-PF₃⁺ is instead more stable than HF-PF₂⁺ by 21.8 kcal mol⁻¹. The proton affinities (PAs) of MF₃ at the M atom range from 91.9 kcal mol⁻¹ (M = Bi) to 156.5 kcal mol⁻¹ (M = P), and follow the irregular periodic trend BiF₃ < SbF₃ < AsF₃ < NF₃ < PF₃. The PAs at the F atom range instead from 131.9 kcal mol⁻¹ (M = P) to 164.9 kcal mol⁻¹ (M = Bi), and increase in the more regular order PF₃ ≈ NF₃ < AsF₃ < SbF₃ < BiF₃. This trend parallels the fluoride-ion affinities of the MF₂⁺ cations. For protonated NF₃ and PF₃, the calculations are in good agreement with the available experimental results. As for protonated AsF₃, they support the formation of HF-AsF₂⁺ rather than the previously proposed H-AsF₃⁺. The calculations indicate also that the still elusive H(SbF₃)⁺ and H(BiF₃)⁺ should be viable species in the gas phase, exothermically obtainable by various protonating agents.     

Pentafluorsulfanylamine und Sulfanylammonium-Salze

Pentafluorosulfanylamines and Sulfanylammonium Salts . From the addition of HF to sulfurtetrafluorideimides N-alkylpentafluorosulfanylamines RNHSF₅(2a, 2b: R=CH₃, C₂H₅) are obtained in quantitative yield. N, N-dialkylpentafluorosuIfanylamines Et₂NSF₅(5a) and pip-SF₅ (5b) are isolated from the reaction of the appropriate sulfurdifluoronitridearnides NSF₂NR₂ and HF/SF₄. Protonation of the amines with the superacidic system HF/AsF₅ gives stable pentafluorosulfanyl-ammonium salts SF₅NHRR′_. AsF₆ (12: R = R′ = CH₃; 14: R=R′=H; 10: R=CH₃, R′ = H). Under the same conditions the adduct AsF₅· NSF₂CF(CF₃)₂ (15) forms a cation with hexacoordinated sulfur (trans-H₃NSF₄CF(CF₃)₂^?AsF₆⁶: 16), while with Asp₅ · NSF₂NMe₂ (17) the reaction stops at tetracoordination (HNSF₂NMe₂⁺AsF₆ : 18).     

The Protonation of Acetamide and Thioacetamide in Super­acidic Solutions: Crystal Structures of [H3CC(OH)NH2]+AsF6– and [H3CC(SH)NH2]+AsF6–

Acetamide and thioacetamide react with the superacid solutions HF/MF₅ (M = As, Sb) under formation of the corresponding salts [H₃CC(OH)NH₂]⁺MF₆^– and [H₃CC(SH)NH₂]⁺MF₆^– (M = As, Sb), respectively. The reaction of DF/AsF₅ with acetamide and thioacetamide lead to the corresponding deuterated salts [H₃CC(OD)ND₂]⁺AsF₆^– and [H₃CC(SD)ND₂]⁺AsF₆^–, respectively_. The salts are characterized by vibrational and NMR spectroscopy, and in the case of [H₃CC(OH)NH₂]⁺AsF₆^– and [H₃CC(SH)NH₂]⁺AsF₆^– also by single‐crystal X‐ray analyses. The [H₃CC(OH)NH₂]⁺AsF₆^– ( 1 ) salt crystallizes in the triclinic space group P$\bar{1}$ with two formula units per unit cell, and the [H₃CC(SH)NH₂]⁺AsF₆^– ( 2 ) salt crystallizes in the monoclinic space group P2₁/c with four formula units per unit cell. In both crystal structures three‐dimensional networks are observed which are formed by intra‐ and intermolecular N–H ··· F and O–H ··· F or S–H ··· F hydrogen bonds, respectively. For the vibrational analyses, quantum chemically calculated spectra of the cations [H₃CC(OH)NH₂ · 3HF]⁺ and [H₃CC(SH)NH₂ · 2HF]⁺ are considered.     

Reaktionen von Ameisensäuremethylester in den supersauren Systemen XF/MF5 (X = H,D; M = As,Sb) und die Kristallstruktur von HC(OH)(OCH3)+AsF6–

Reactions of Formic Acid Methylester in the Super Acidic System XF/MF₅ (X = H, D: M = As, Sb) and the Crystal Structure of HC(OH)(OCH₃)⁺AsF₆^– The reaction of formic acid methyl ester in the superacidic system XF/MF₅ (X = H, D: M = As, Sb) leads to the hydroxy methoxy carbenium hexafluorometallates. The very hydrolysable and thermo labile salts are characterized by vibrational and NMR spectroscopic methods. Under inert conditions they are stable at –20 °C for some weeks. HC(OCH₃)(OH)⁺AsF₆^– crystallizes in the monoclinic space group P2₁/c (No. 14) with a = 5.275(1) Å, b = 11.059(1) Å, c = 12.113(1) Å und β = 96.64(1)° and four formula units per cell.     

Preparation and Characterization of Protonated Fumaric Acid

Fumaric acid was reacted with the binary superacidic systems HF/SbF₅ and HF/AsF₅. The O,O'-diprotonated [C₄H₆O₄]²⁺([MF₆]^–)₂ (M = As, Sb) and the O-monoprotonated [C₄H₅O₄]⁺[MF₆]^– (M = As, Sb) species are formed depending on the stoichiometric ratio of the Lewis acid to fumaric acid. The colorless salts were characterized by low-temperature vibrational spectroscopy. In case of the hexafluoridoantimonates single-crystal X-ray structure analyses were carried out. The [C₄H₆O₄]²⁺([SbF₆]^–)₂ crystallizes in the monoclinic space group C2/c with four formula units per unit cell and [C₄H₅O₄]⁺[SbF₆]^– crystallizes in the triclinic space group P1 with one formula unit per unit cell. The protonation of fumaric acid does not cause a notable change of the C=C bond length. The experimental data are discussed together with quantum chemical calculations of the cations [C₄H₆O₄ · 4 HF]²⁺ and [C₄H₆O₄ · 2 H₂CO · 2 HF]²⁺.     

Dihydroxycarbeniumhexafluorometallate – Synthese,spektroskopische Charakterisierung sowie Kristallstruktur von HC(OH)2+AsF6−

Dihydroxycarbeniumhexafluorometallates – Synthesis, Spectroscopic Characterization, and Crystal Structure of HC(OH)₂⁺AsF₆^? The preparation of HC(OH)₂⁺ MF₆^? (M = As, Sb) by protonation of HCOOH in the superacid systems HF/MF₅ is reported. The very hydrolysable and thermolabile salts are characterized by vibrational and NMR spectroscopic methods. Under inert conditions they are stable at ?40°C for some weeks. HC(OH)₂⁺AsF₆^? crystallizes in the orthorhombic space group Pbca (No. 61) with a = 965.8(1), b = 1582.20(16), c = 766.40(8) pm with eight formula units per unit cell.     

Metal (II) hexafluoroarsenates: Thermal decomposition studies on the adducts MF2·2AsF5 (M = Mg,Ca, Sr,Mn, Co,Ni, Cd,Hg, Pb), 2MF2·3AsF5 (M = Fe,Cu, Zn) and MF2·AsF5 (M = Ag,Sn)

Thermal studies have shown that metal(II) hexafluoro-arsenates of the types MF₂·2AsF₅ ( M = Mg, Ca, Sr, Mn, Co, Ni, Cd, Hg, Pb), 2MF₂·3AsF₅ (M = Fe, Cu, Zn) and MF₂·AsF₅ (M = Ag, Sn), prepared by the reaction of metal difluorides with AsF₅ in anhydrous HF at room temperature, decompose when heated in an argon atmosphere. In all cases AsF₅ is given off. For some of the adducts the decompositions proceed in one or more steps to give the original difluorides, but for others, the decompositions overlap one another. The greatest range of intermediate stoicheiometries results from the decompositions of the MF₂·2AsF₅ type adducts in which the metal difluoride content is a minimum. In decompositions of adducts of this type as many as three different intermediates, 2MF₂·3AsF₅, MF₂·AsF₅ and 2MF₂·AsF₅, may be observed.     

Reaktionen von Trimethylstiban in den supersauren Systemen XF/MF5 (X = H,D; M = As,Sb), Kristallstrukturen von (CH3)3SbD+SbF6– und (CH3)3SbSb(CH3)32+(SbF6–)2 · SO2

Reactions of Trimethylstibine in the Superacidic Systems XF/MF₅ (X = H, D; M = As, Sb), Crystal Structures of (CH₃)₃SbD⁺SbF₆^– and (CH₃)₃SbSb(CH₃)₃²⁺(SbF₆^–)₂ · SO₂ The reaction of trimethylstibine in the superacidic systems XF/MF₅ (M = As, Sb; X = H, D) leads to the trimethylstibonium hexafluorometallates. The resulting salts are characterised by vibrational spectroscopy and their crystal structures. Decomposition of trimethylstibonium hexafluoroantimonate in sulphur dioxide at room temperature ends in the formation of hexamethyldistibonium bis(hexafluoroantimonate) as a sulphur dioxide adduct, verified by its crystal structure and vibrational spectra.     

The preparation of copper(II) and copper(I) salts in acetonitrile using group VA and VB pentafluorides

Copper(II) fluorine reacts with the pentafluorides, TaF₅, PF₅, and AsF₅, in acetonitrile to give solvated Cu^II, hexafluoroanion salts. These react with copper metal to give the corresponding Cu^I compounds. Similar reactions occur between AsF₅ and silver(I) or thallium(I) fluorides, but silver(II) fluoride reacts with MeCN, and Ag^I hexafluoroarsenate is formed. PF₅ oxidises Cu slowly in MeCN to give Cu^I hexafluorophosphate, but AsF₅ has no oxidising ability towards metals in MeCN. Spectroscopic data for Cu(MF₆)₂·5MeCN and Cu(MF₆)·4MeCN (M = Ta or P) are discussed.     

Über die oxidative Fluorierung von (CF3)(R) (R = CF3, Cl) und die Kristallstruktur von (CF3)(Cl)F+ AsF6−

Oxidative Fluorination of (CF₃)(R) (R = CF₃, Cl) and the Crystal Structure of (CF₃)(Cl) F⁺ AsF₆^? Oxidative fluorination of (CF₃)(R) (R = CF₃, Cl) with XeF⁺MF₆^? (M = As, Sb) in anhydrous HF results in formation of monofluorsulfonium hexafluorometalates. The salts are characterized by vibrational, NMR, and mass spectra. (CF₃)(Cl)F⁺ AsF₆^? crystallizes in the monoclinic space group P2₁/c with a = 9.955(10) Å, b = 11.050(5) Å, c = 12.733(15) Å, β = 97.77(5)°, and Z = 4.     

Darstellung der Iminiumsalze CF3?NXCF2+MF6− (X = CH3, F und M = As,Sb) und CF3?NCl = CF2+ AsF6−

Preparation of the Iminium Salts CF₃? NX?CF₂⁺MF₆^? (X = CH₃, F and M = As, Sb) and CF₃? NCl?CF₂⁺ AsF₆^? The preparation of the iminiumsalts CF₃? NX?CF₂⁺ MF₆^? (X = CH₃, F and M = As, Sb) and CF₃? NCl?CF₂⁺ AsF₆^? is reported. The salts were characterized by NMR and infrared spectroscopy. CF₃? NCH₃?CF₂⁺MF₆^? decompose into MF₅ and (CF₃)₂NCH₃.