A specific method for the preparation of many transition metal and actinide oxide tetrafluorides

A general method for the preparation of many transition metal and actinide oxide tetrafluorides by oxygen-fluorine exchange of their respective hexafluorides using boric oxides is described. This simple procedure affords the preparation of MoOF₄, WOF₄, ReOF₄, OsOF₄ and UOF₄ in high yield while reaction of boric oxide with IrF₆ and RuF₆ leads to the preparation of lower fluorides of these elements. The preparation of oxide tetrafluorides by reaction of their oxide tetrachlorides with anhydrous HF has also been investigated, as well as a study of some halogen-exchange reactions of the oxide tetrafluorides.     

Reactions of chlorine monofluoride with tetrasulphur tetranitride,thiazyl chloride and thiazyl fluoride

Chlorine monofluoride reacts with tetrasulphur tetranitride to give thiazyl chloride (monomer and trimer) and thiazyl fluoride; with further ClF, NSCl reacts to form NSF then ClNSF₂, and finally N₂, Cl₂ and SF₄. The reaction NSCl/ClF to give NSF/Cl₂ reverses in SO₂ solvent due to removal of ClF as SO₂ClF. NSF was prepared, in a new method, by passing NSCl through a column of CsF at 110°.     

Extending the Row of Lanthanide Tetrafluorides: A Combined Matrix‐Isolation and Quantum‐Chemical Study

Only the neutral tetrafluorides of Ce, Pr, and Tb as well as the [LnF₇]^3? anions of Dy and Nd, with the metal in the +IV oxidation state, have been previously reported. We report our attempts to extend the row of neutral lanthanide tetrafluorides through the reaction of laser‐ablated metal atoms with fluorine and their stabilization and characterization by matrix‐isolation IR spectroscopy. In addition to the above three tetrafluorides, we found two new tetrafluorides, ³NdF₄ and ⁷DyF₄, both of which are in the +IV oxidation state, which extends this lanthanide oxidation state to two new metals. Our experimental results are supported by quantum‐chemical calculations and the role of the lanthanide oxidation state is discussed for both the LnF₄ and [LnF₄]^? species. Most of the LnF₄ species are predicted to be in the +IV oxidation state and all of the [LnF₄]^? anions are predicted to be in the +III oxidation state. The LnF₄ species are predicted to be strong oxidizing agents and the LnF₃ species are predicted to be moderate to strong Lewis acids.     

Symmetry of chloronium ions from ionic reaction of chlorine, chlorine monofluoride gas, and chlorine monofluoride complex with terminal alkenes

Ionic chlorination of 1H,1H,7H-perfluorohept-1-ene (2) and heptafluoropropyl trifluorovinyl ether (4) with chlorine monofluoride (ClF) gas in aprotic solvent; and alkenes 2, 1H-perfluorohept-1-ene (3E), and 4 with chlorine (Cl₂) in protic solvent were investigated. Regiochemical data from SN₂-like ring-opening of the intermediate was used to predict the symmetry of the chloronium ion. The chloronium ions from perfluorohydroalkene 2 with two terminal hydrogens were found to be unsymmetrical with positive charge localized on the terminal carbon. However, reaction of ClF_(g) with 3E containing a single terminal fluorine atom gave data suggesting a symmetrical chloronium ion. Alkene 4 contains a heptafluoropropyl ether group that stabilizes positive charge on the number-2 carbon and it is reactive enough to give products with the sluggish ClF complex generated in situ. Reactive eletrophiles ClF_(g), Cl_2(g), or the less reactive ClF complex, give an unsymmetrical chloromium ion with charge localized on the internal number-2 carbon.     

The formation of oxygen-containing perfluorocyclohexadien-1-yliodine tetrafluorides

The electrophilic oxygenation of pentafluorophenyl iodo compounds C₆F₅IF_n with iodine in different valencies (n = 0, 2, 4) using XeF₂-H₂O in HF allowed access to new organoiodine(V) compounds, namely isomeric oxopentafluorocyclohexadien-1-yliodine tetrafluorides, C₆(O)F₅IF₄.     

Syntheses and vibrational spectra of xenon(VI) fluorozirconate(IV) and xenon(VI) fluorohafnate(IV)

Liquid xenon difluoride at 140°C does not react with zirconium or hafnium tetrafluorides, neither does liquid xenon hexafluoride at 60°C. Therefore reactions between the corresponding hydrazinium fluorometalates or ammonium fluorometalates and xenon difluoride and xenon hexafluoride, respectively, were carried out. N₂H₆ZrF₆ and N₂H₆HfF₆ react with xenon difluoride at 60°C again yielding only the corresponding tetrafluorides, while the analogous reaction with (NH₄)₂ZrF₆ and (NH₄)₂HfF₆ proceeds at 170°C yielding the corresponding ammonium pentafluorometalates, which are stable and do not react further with excessive xenon difluoride up to 200°C.The reaction between N₂H₆ZrF₆ or N₂H₆HfF₆ and xenon hexafluoride proceeds at room temperature yielding a series of thermally unstable compounds of the type mXeF₆.MF₄ (M = Zr, Hf) where m ? 6. The final products which are stable at room temperature are XeF₆.MF₄ (M = Zr,Hf). Spectroscopic evidence suggests that these compounds are salts of a XeF⁺₅ cation squashed between a polymeric anion of the type (MF₅)^x-_x.     

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.     

Donor Acceptor Complexes between the Chalcogen Fluorides SF2, SeF2, SeF4 and TeF4 and an N-Heterocyclic Carbene

The majority of binary chalcogen fluorides are fiercely reactive and extremely difficult to handle. Here, we show that access to crystalline donor-acceptor complexes between chalcogen difluorides (sulfur, selenium) and tetrafluorides (selenium, tellurium) with the N-heterocyclic carbene (NHC) 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene (IPr) is possible conveniently and safely without the need to generate the highly unstable EF₂ (E=S, Se) or the very toxic and corrosive SeF₄.     

Electrophilic monofluoromethylation of O-, S-, and N-nucleophiles with chlorofluoromethane

CH₂ClF has been found to be a useful electrophilic monofluoromethylating agent for a variety of O-, S-, and N-nucleophiles. The reaction is not sensitive to the radical scavenger such as nitrobenzene, which strongly supports an S_N2 mechanism rather than an SET mechanism. Although most of these products (fluoromethyl ethers, sulfides, and amines) can be isolated with good purity, some of these compounds do intend to decompose (via defluorination) during storage. The electrophilic monofluoromethylation of carbon-nucleophiles was attempted with CH₂ClF, CH₂FI, or FCH₂OTs as monofluoromethylating agents, but with no success.     

Zirconium tetrachloride revisited

Zirconium tetrachloride, ZrCl₄, is a strategic material with wide‐ranging applications. Until now, only one crystallographic study on ZrCl₄ has been reported [Krebs (1970). Z. Anorg. Allg. Chem. 378 , 263–272] and that was more than 40 years ago. The compound used for the previous determination was prepared from ZrO₂ and Cl₂–CCl₄, and single‐crystal X‐ray diffraction (SCXRD) studies on ZrCl₄ obtained from Zr metal have not yet been reported. In this context, we prepared ZrCl₄ from the reaction of Zr metal and Cl₂ gas in a sealed tube and investigated its structure at 100, 150, 200, 250, and 300 K. At 300 K, the SCXRD analysis indicates that ZrCl₄ crystallizes in the orthorhombic space group Pca2₁ [a = 6.262 (9), b = 7.402 (11), c = 12.039 (17) Å, and V = 558.0 (14) ų] and consists of infinite zigzag chains of edge‐sharing ZrCl₆ octahedra. This chain motif is similar to that observed previously in ZrCl₄, but the structural parameters and space group differ. In the temperature range 100–300 K, no phase transformation was identified, while elongation of intra‐chain Zr…Zr [3.950 (1) Å at 100 K and 3.968 (5) Å at 300 K] and inter‐chain Cl…Cl [3.630 (3) Å at 100 K and 3.687 (9) Å at 300 K] distances occurred.     

Thermal decomposition of hydrazinium(2+) hexafluorozirconate(IV) and hexafluorohafnate(IV)

A study of the thermal decomposition of N₂H₆ZrF₆ and N₂H₆HfF₆ showed that in the first step N₂H₅ZrF₅ and N₂H₅HfF₅ are formed. In the second step the former gives NH₄ZrF₅ as an intermediate, but an analogous hafnium complex cannot be obtained in a pure state. The end products of the decompositions are the corresponding tetrafluorides. The intermediates were isolated and characterized by chemical analysis X-ray diffraction patterns and vibrational spectroscopy.     

Comparative study of XO···ClF and XS···ClF (X = H,CH3, and F) halogen‐bonded complexes

Quantum chemical calculations have been performed to study the single‐electron halogen bonds in HO···ClF and HS···ClF complexes. The calculation methods have a larger effect on the S···Cl halogen bond than on the O···Cl one. The interaction strength in HO···ClF complex is stronger than that in HS···ClF one, but the presence of methyl group in the halogen acceptor makes the sequence reverse. The methyl group has a greater effect on the S···Cl halogen bond than on the O···Cl one. The charge analyses indicate that the methyl group is electron‐donating and the electron‐donating role in the H₃CS? ClF complex is larger than in the H₃CO? ClF one. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011     

Unambiguous Proof for Alcoxycarbonyl-group Migration in Wagner-Meerwein Rearrangements

In HSO₃F/SO₂ClF the β-hydroxy esters Ph-CHOH-CMe₂-COOR ( 1 , R?Me, Et) are doubly protonated, then transformed into the fluorosulfates 7 and (partly) into the fluorides 8. At ?15°, both 7 and 8 undergo a rearrangement, forming derivatives of Me₂C?C(Ph)COOR ( 2 ). By labelling 1 with ¹³C, singly (¹³C(3)) and doubly (¹³C(1,3)), it could be shown that exclusively the ROOC groups undergo a 1,2-shift. Compound 2 is also formed in HSO₃F/SO₂ClF from the isomeric Me₂COH-CHPh-COOR ( 3 ) by elimination, and less easily from the α-hydroxy ester Ph-CMe₂-CHOH-COOR (5) via a phenyl 1,2-shift. Another isomer, Ph-C(OH)Me-CHMe-COOR (4) gives products different from 2 . Using more acidic systems containing SbF₅, the free carbenium ions 13 (Ph-CH⁺-CMe₂-COOR) can be stabilized; they do not form 2 , possibly because of complexation of the ester group with SbF₅. The energy profile and the mechanism of the rearrangement 1 → 2 are discussed.     

Cadmium copper tetrachloride tetrahydrate

The double salt [CuCl₂(H₂O)₂{CdCl₂}]·2H₂O crystallizes in the triclinic rather than the monoclinic system as reported previously. The structure consists of sheets in the ac plane with slightly distorted octahedral CdCl₆ [Cd—Cl 2.5813 (8)–2.6943 (8) Å] connected by Cd—Cl—Cd bridges in the Cd equatorial plane along a , and by Cd—Cl—Cu bridges to layers of square‐planar CuCl₂(H₂O)₂ along c . There are long axial Cu—Cl interactions of 2.8623 (7) Å and additional water of hydration is hydrogen bonded to coordinated water and chloride ligands. The additional water connects the ac sheets into a three‐dimensional network. Both Cd and Cu occupy different sites. The Cu?Cu and Cd?Cd distances are 3.8274 (6) Å.     

Molecular Dynamics Simulation Study of ClF in Water: Halogen Bonding Interaction in Liquid

Does the halogen bonding interaction co-exist in liquid when it competes with the hydrogen bonding interaction? The classical molecular dynamics simulations for the solvation properties of ClF molecule in water are performed with the Lennard-Jones plus Coulomb electrostatic potential parameters that are optimized with ab initio interaction energy calculations for the pre-reactive H₂O…ClF complex. We find that the halogen bonding interactions occur between O and Cl atoms and have the comparable strength and population with respect to the hydrogen bonding interactions of Cl…H.     

Preparation of polyfluorinated cycloalk-1-enyl-, alk-1-enyl-, and alkyliodine tetrafluorides using XeF2 in the presence of appropriate Lewis acids as fluorooxidant

Previously unknown polyfluorocyclohexenyl, and acyclic perfluoroalkenyliodine tetrafluorides were prepared in high yields. Perfluorocyclohex-1-enyliodine tetrafluoride was obtained from pentafluoroiodobenzene using XeF₂-NbF₅ in aHF. The reaction of C₆F₅I with the weaker fluorooxidant XeF₂-BF₃ in 1,1,1,3,3-pentafluorobutane (PFB) yielded C₆F₅IF₂, perfluorocyclohexa-1,4-dienyliodine difluoride, C₆F₅IF₄, perfluorocyclohexa-1,4, and 1,3-dienyliodine tetrafluoride as intermediate products on parallel reaction routes. Both perfluoroalkenyl iodides, cis- and trans-(CF₃)₂CFCFCFI, reacted with XeF₂-BF₃ in PFB to give the corresponding perfluoroalkenyliodine tetrafluorides, cis- and trans-(CF₃)₂CFCFCFIF₄. Even perfluoroalkyl iodides can be fluorinated by this reagent as was demonstrated by the preparation of C₆F₁₃IF₄ from C₆F₁₃I. Generally, the CFCIF_n fragment (n = 0, 2, or 4) in cyclic or acyclic perfluoroalkenyliodine compounds R_FIF_n did not undergo a transformation to the corresponding perfluoroalkyliodine compound. Furthermore, no perfluoroorganoiodine hexafluorides were detected in reactions with the fluorooxidant XeF₂-aHF or BF₃ or NbF₅.     

The electric hyperfine interaction in some covalent bonded fluorine molecules

With the time differential perturbed angular distribution method (TDPAD) we have investigated the electric hyperfine interaction in the fluorine molecule, group IV tetrafluorides and group V trifluorides. The value of the efg for the F₂-molecule is in good agreement with recent theoretical calculations. The results for the tetra- and trifluorides are discussed in the framework of the Townes and Dailey theory.     

Protonation of 1,4-bis(1-vinyl-2-pyrrolyl)benzene

In the reaction of 1,4-bis(1-vinyl-2-pyrrolyl)benzene with hydrogen chloride and hydrogen bromide the hydrogen halide adds at the vinyl groups, and -protonation takes place in both pyrrole rings. In reaction with the superacidic system HSO₃F+SbF₅ (in SO₂ClF) position 5 of one heterocycle and position 4 of the other are protonated with retention of the vinyl groups.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1041–1045, August, 1991.     

Photochemical water reduction by molybdenum tetrachloride

The photolysis of MoCl₄(MeCN)₂ in MeCN in the presence of small amounts of H₂O proceeds according to the equation Mo^IVCl₄·H₂OMo^VIOCl₄ + H₂. It is suggested that a ligand field excited state of MoCl₄(H₂O) _n , which is initially populated by light absorption, is deactivated to a reactive metal-to-ligand (Mo^IVH₂O) charge transfer state.