The Preparation of Dioxygenyl Salts from Dioxygen Difluoride

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.