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

Igor M Shlyapnikov, Hélène P A Mercier, Evgeny A Goreshnik, Gary J Schrobilgen, Zoran Mazej

Inorg Chem. 2013 Aug 5;52(15):8315-26.

PMID: 23837817

Abstract:

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. In the crystal structure of [ImH]2[TiF6]·2HF, two HF molecules are coordinated to each [TiF6](2-) anion by means of strong F-H···F hydrogen bonds. The [Ti2F11](3-) anion of [ImH]3[Ti2F11] results from association of two TiF6 octahedra through a common fluorine vertex. Three crystallographically independent [Ti2F11](3-) anions, which have distinct geometries and orientations, are hydrogen-bonded to the [ImH](+) cations. The [ImH]4[Ti4F20] salt crystallized in two crystal modifications at low (α-phase, 200 K) and ambient (β-phase, 298 K) temperatures. The tetrameric [Ti4F20](4-) anion of [ImH]4[Ti4F20] consists of rings of four TiF6 octahedra, which each share two cis-fluorine vertices, whereas the pentameric [Ti5F23](3-) anion of [ImH]3[Ti5F23] results from association of five TiF6 units, where four of the TiF6 octahedra share two cis-vertices, forming a tetrameric ring as in [Ti4F20](4-), and the fifth TiF6 unit shares three fluorine vertices with three TiF6 units of the tetrameric ring. The [ImH][Ti2F9] salt also crystallizes in two crystal modifications at low (α-phase, 200 K) and high (β-phase, 298 K) temperatures and contains polymeric ([Ti2F9](-))∞ anions, which appear as two parallel infinite zigzag chains comprised of TiF6 units, where each TiF6 unit of one chain is connected to a TiF6 unit of the second chain through a shared fluorine vertex. Quantum-chemical calculations at the B3LYP/SDDALL level of theory were used to arrive at the gas-phase geometries and vibrational frequencies of the [Ti4F20](4-) and [Ti5F23](3-) anions, which aided in the assignment of the experimental vibrational frequencies of the anion series.

Chemicals Related in the Paper:

Catalog Number	Product Name	Structure	CAS Number	Price
AP79821639	Poly[4-vinylpyridinium poly(hydrogen fluoride)]		79821-63-9	Price

Catalog Number

Product Name

Structure

CAS Number

Price

AP79821639

Poly[4-vinylpyridinium poly(hydrogen fluoride)]

79821-63-9

Price

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