Increasing Structural Dimensionality of Alkali Metal Fluoridotitanates(IV).

Reactions between AF (A = Li, Na, K, Rb, Cs) and TiF (with starting n(AF):n(TiF) molar ratios in the range from 3:1 to 1:3) in anhydrous hydrogen fluoride yield [TiF], [TiF], [TiF], [TiF], and [TiF] salts. With the exception of the ATiF compounds, which consist of A cations and octahedral [TiF] anions, all of these materials arise from the condensation of TiF units. The anionic part in the crystal structures of A[TiF] (A = K, Cs) and A[TiF]·HF (A = Na, K, Rb) is composed of infinite ([TiF]) chains built of TiF octahedra sharing joint vertices.

Cerium Tetrafluoride: Sublimation, Thermolysis, and Atomic Fluorine Migration.

Saturated vapor pressure p° and enthalpy of sublimation (ΔsH°) of cerium tetrafluoride CeF4 were determined by means of Knudsen effusion mass spectrometry in the range of 750-920 K. It was discovered that sublimation of cerium tetrafluoride from a platinum effusion cell competes with thermal decomposition to CeF3 in the solid phase, but no accompanying release of fluorine to the gas phase occurs. Thus, fluorine atoms migrate within the surface layer of CeF4(s) to the regions of their irreversible drain.

Crystal structures and Raman spectra of imidazolium poly[perfluorotitanate(IV)] salts containing the [TiF6]2-, ([Ti2F9]-)∞, and [Ti2F11]3- and the new [Ti4F20]4- and [Ti5F23]3- anions.

Reactions between imidazole (Im, C3H4N2) and TiF4 in anhydrous hydrogen fluoride (aHF) in different molar ratios have yielded [ImH]2[TiF6]·2HF, [ImH]3[Ti2F11], [ImH]4[Ti4F20], [ImH]3[Ti5F23], and [ImH][Ti2F9] upon crystallization. All five structures were characterized by low-temperature single-crystal X-ray diffraction. The single-crystal Raman spectra of [ImH]4[Ti4F20], [ImH]3[Ti5F23], and [ImH][Ti2F9] were also recorded and assigned.

The cubic [Ti8F36]4- anion found in the crystal structures of K4Ti8F36·8HF and Rb4Ti8F36·6HF.

X-ray diffraction study of K4Ti8F36·8HF and Rb4Ti8F36·6HF reveals a novel type of octameric cubic [M8F36](4-) anion built from eight M(IV)F6 octahedra.