Lithium tetra­chlorido­aluminate, LiAlCl4: a new polymorph (oP12, Pmn21) with Li+ in tetra­hedral inter­stices

Acta Crystallographica Section E: Crystallographic Communications

Prö¹  mper, S.W.²  Frank, W.⁵ 

[1] Institut für Anorganische Chemie und Strukturchemie, Lehrstuhl II: Material- und Strukturforschung, Heinrich-Heine-Universitässeldorf, Germany;sseldorf, Universität Dütsstrasse 1, D-40225 Dü

关键词: CRYSTAL STRUCTURE;    POLYMORPHISM;    LITHIUM TETRACHLORIDOALUMINATE;   

DOI  :  10.1107/S205698901701235X

学科分类：数学（综合）

来源: International Union of Crystallography

【 摘 要 】

Dissolving lithium chloride and aluminium chloride in boiling para- or meta-xylene and keeping the colourless solution at room temperature led to crystal growth of a new modification of lithium tetra­chlorido­aluminate, LiAlCl4, which represents a second modification (oP12, Pmn21) of the ternary salt besides the long known monoclinic form [LiAlCl4(mP24, P21/c); Mairesse et al. (1977). Cryst. Struct. Commun. 6, 15–18]. The crystal structures of both modifications can be described as slightly distorted hexa­gonal closest packings of chloride anions. While the lithium cations in LiAlCl4(mP24) are in octa­hedral coordination and the aluminium and lithium ions in the solid of ortho­rhom­bic LiAlCl4 occupy tetra­hedral inter­stices with site symmetries m and 1, respectively, the lithium cation site being half-occupied (defect wurtz-stannite-type structure). From differential scanning calorimetry (DSC) measurements, no evidence for a phase transition of the ortho­rhom­bic modification is found until the material melts at 148 °C (Tpeak = 152 °C). The melting point is nearly identical to the literature data for LiAlCl4(mP24) [146 °C; Weppner & Huggins (1976). J. Electrochem. Soc. 124, 35–38]. From the melts of both polymorphs, the monoclinic modification recrystallizes.

【 授权许可】

CC BY