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

Abstract

Reactions between XeF₂, TiF₄ and UV-irradiated elemental F₂ in anhydrous HF yielded XeF₅TiF₅ (XeF₆·TiF₄), [XeF₅]₅[Ti₁₀F₄₅] (XeF₆·2TiF₄), and [XeF₅][Ti₃F₁₃] (XeF₆·3TiF₄) upon crystallization. [XeF₅]₅[Ti₁₀F₄₅] crystallizes in two crystal modifications at low (α-phase, 150 K) and ambient (β-phase, 296 K) temperatures. The crystal structure determination of [XeF₅]₅[Ti₁₀F₄₅] reveals the largest known discrete decameric [Ti₁₀F₄₅]⁵⁻ anion built from ten TiF₆ octahedra, sharing vertices, in the shape of a double-star. [XeF₅]⁺ cations are completely ordered in the α-phase, while one of three crystallographically unique [XeF₅]⁺ cations is two-fold disordered in the β-phase. The anionic part of [XeF₅][Ti₃F₁₃] is built from tetrameric Ti₄F₂₀ and octameric Ti₈F₃₆ units sharing vertices and alternatively linked into ([Ti₃F₁₃]⁻)_∞ columns. The charge balance is maintained by [XeF₅]⁺ cations which form secondary Xe⋯F contacts with fluorine atoms of ([Ti₃F₁₃]⁻)_∞ groups. The main structural feature of XeF₅TiF₅ is an infinite chain of distorted TiF₆ octahedra joined by cis vertices.