title: About the polymorphism of [Li(C4H8O)3]I: crystal structures of trigonal and tetra-gonal polymorphs.
abstract: Two new trigonal and tetra-gonal polymorphs of the title compound, iodido-tris-(tetra-hydro-furan-κO)lithium, are presented, which both include the isolated ion pair Li(THF)3 (+)·I(-). One Li-I ion contact and three tetra-hydro-furan (THF) mol-ecules complete the tetra-hedral coordination of the lithium cation. The three-dimensional arrangement in the two polymorphs differs notably. In the trigonal structure, the ion pair is located on a threefold rotation axis of space group P-3 and only one THF mol-ecule is present in the asymmetric unit. In the crystal, strands of ion pairs parallel to [001] are observed with an eclipsed conformation of the THF mol-ecules relative to the Li⋯I axis of two adjacent ion pairs. In contrast, the tetra-gonal polymorph shows a much larger unit cell in which all atoms are located on general positions of the space group I41 cd. The resulting three-dimensional arrangement shows helical chains of ion pairs parallel to [001]. Apart from van der Waals contacts, no remarkable inter-molecular forces are present between the isolated ion pairs in both structures.
authors.affiliation: University of Regensburg, Institute of Inorganic Chemistry, Universitätsstrasse 31, 93053 Regensburg, Germany.
authors.forename: Stefanie
authors.initials: S
authors.lastname: Gärtner
authors.affiliation: University of Regensburg, Institute of Organic Chemistry, Universitätsstrasse 31, 93053 Regensburg, Germany.
authors.forename: Tobias
authors.initials: T
authors.lastname: Gärtner
authors.affiliation: University of Regensburg, Institute of Organic Chemistry, Universitätsstrasse 31, 93053 Regensburg, Germany.
authors.forename: Ruth-Maria
authors.initials: RM
authors.lastname: Gschwind
authors.affiliation: University of Regensburg, Institute of Inorganic Chemistry, Universitätsstrasse 31, 93053 Regensburg, Germany.
authors.forename: Nikolaus
authors.initials: N
authors.lastname: Korber
keywords: THF solvate; crystal structure; lithium complexes; polymorphism