Zur kenntnis von [O 2 ] + [Mn 2 F 9 ] −

Further Insights into the Chemical Synthesis of F2 and on Drying moist HF

It is well established that solid K2MnF6 reacts with excess SbF5 forming elemental F2. However, if the reaction is carried out in anhydrous HF (aHF) as a solvent, this is surprisingly not the case. Instead, the green Mn(IV) compound K3[(MnIVF)(SbF6)5]F is obtained. The reductive elimination of F2 was not observed under the applied conditions. The compound was characterized by its crystal structure, by Raman spectroscopy, and by quantum-chemical solid-state calculations. It crystallizes in the monoclinic space group P21/c, mP164, with the lattice parameters a = 12.2393(13), b = 12.167(2), c = 20.115(5) Å, β = 110.805(8)°, V = 2800.1(9) Å3, Z = 4 at T = 200 K. As the use of strictly anhydrous HF is crucial in this and other similar reactions, methods for drying moist HF are discussed.

Strategies to Achieve Stable Manganese Oxyfluorides by Tuning the Reactivity of Pure Molecular Fluorine

Thanks to their high initial electrochemical properties and broad compositional flexibility, lithium-rich disordered rocksalt cathode-active materials including high-performance manganese-only materials appear as a potential replacement to the cobalt-based current market leader "NMC" material. The main issue with these materials is their lack of stability. However, recent works have identified bulk fluorination as a potential solution to stabilize these compounds. There is, however, a clear lack of diversity in fluorination agents used to synthesize these disordered rocksalts, as most publications used LiF, a very stable compound. To achieve manganese-only materials, manganese oxyfluorides represent promising precursors, but the literature reports only MnO3F and Mn2O2F9, which are both unstable and hazardous. The present study develops several strategies for synthesis and a tailored characterization methodology to explore the chemical space of direct fluorination of manganese oxide MnO with molecular fluorine and shows how to tune its reactivity to achieve a range of novel, safe, and finely tunable manganese oxyfluorides of general formula MnOFx, with x going from 0 to 1 synthesized via a fluorine insertion mechanism.

Syntheses of Dioxygenyl Salts by Photochemical Reactions in Liquid Anhydrous Hydrogen Fluoride: X-ray Crystal Structures of α- and β-O2Sn2F9, O2Sn2F9·0.9HF, O2GeF5·HF, and O2[Hg(HF)]4(SbF6)9

By treating gaseous, liquid, or solid fluorides with UV-photolyzed O₂/F₂ mixtures and by treating solid oxides with UV-photolyzed F₂ (or O₂/F₂ mixtures) in liquid anhydrous HF at ambient temperature, we investigated the possibility of the preparation of O₂M^IIIF₄ (M = B, Fe, Co, Ag), O₂M^IVF₅ (M = Ti, Sn, Pb), (O₂)₂M^IVF₆ (M = Ti, Ge, Sn, Pb, Pd, Ni, Mn), O₂M^IV₂F₉ (M = Sn), O₂M^VF₆ (M = As, Sb, Au, Pt), O₂M^V₂F₁₁ (M = Pt), O₂M^VIF₇ (M = Se), (O₂)₂M^VIF₈ (M = Mo, W), and O₂M^VIIF₈ (M = I). The approach has been successful in the case of previously known O₂BF₄, O₂MF₆ (M = As, Sb, Au; Pt), O₂GeF₅, and (O₂)₂(Ti₇F₃₀). Novel compounds O₂GeF₅·HF, α-O₂Sn₂F₉ (1-D), and the HF-solvated and nonsolvated forms of β-O₂Sn₂F₉ (2-D) were synthesized and their crystal structures determined using single-crystal X-ray diffraction. The crystal structures of all of these materials arise from the condensation of octahedral MF₆ (M = Ge, Sn) units. The anion in the crystal structure of O₂GeF₅·HF is comprised of infinite ([GeF₅]⁻)_∞ chains of GeF₆ octahedra that share common vertices. The HF molecules and O₂⁺ cations are located between the chains. The crystal structure of α-O₂SnF₉ (1-D) is constructed from [O₂]⁺ cations and polymeric ([Sn₂F₉]⁻)_∞ anions which appear as two parallel infinite chains comprised of SnF₆ units, where each SnF₆ unit of one chain is connected to a SnF₆ unit of the second chain through a shared fluorine vertex. The single-crystal structure determination of [O₂][Sn₂F₉]·0.9HF reveals that it is comprised of two-dimensional ([Sn₂F₉]⁻)_∞ grids with [O₂]⁺ cations and HF molecules located between them. The 2-D grids have a wavelike conformation. The ([Sn₂F₉]⁻)_∞ layer contains both six- and seven-coordinated Sn(IV) atoms that are interconnected by bridging fluorine atoms. A new, more complex [O₂]⁺ salt, O₂[Hg(HF)]₄[SbF₆]₉, was prepared. In its crystal structure, the Hg atoms bridge to SbF₆ units to form a 3-D framework. The O₂⁺ cations are located inside the voids while the HF molecules are bound to Hg atoms through the F atom. Attempts to prepare several chlorine analogues of O₂⁺ fluorine salts (i.e., O₂TiCl₅ and O₂MCl₆ (M = Nb, Sb)) failed.

Reactions between fluorides and/or oxides and UV-irradiated F₂ and/or F₂/O₂ mixtures were carried out in anhydrous hydrogen fluoride at ambient temperature to prepare O₂⁺ salts. The crystal structures of O₂GeF₅·HF and O₂GeF₅ consist of infinite polymeric ([GeF₅]⁻)_∞ anions. The O₂Sn₂F₉ salt exhibits polymorphism consisting of a 1-D phase built from double chainlike ([Sn₂F₉]⁻)_∞ anions and a 2-D phase built from layerlike anions. The latter also exists as a solvated form O₂Sn₂F₉·nHF. The crystal structure of O₂[Hg(HF)]₄(SbF₆)₉ is isotypic to that of H₃O[Cd(HF)]₄(SbF₆)₉. The Hg atoms are bridged by SbF₆ groups forming a 3-D framework with O₂⁺ cations located inside the voids. The HF molecules are bound to Hg atoms through the F atom.

Largest perfluorometallate [Ti10F45]5−oligomer and polymeric ([Ti3F13]−)∞and ([TiF5]−)∞anions prepared as [XeF5]+salts

[XeF₅]₅[Ti₁₀F₄₅] consists of the largest known discrete [Ti₁₀F₄₅]⁵⁻anion built from ten TiF₆octahedra, in the shape of a double-star.