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About the polymorphism of [Li(C4H8O)3]I: crystal structures of trigonal and tetra-gonal polymorphs.

Gärtner S, Gärtner T, Gschwind RM, Korber N - Acta Crystallogr Sect E Struct Rep Online (2014)

Bottom Line: 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.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.

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Affiliation: University of Regensburg, Institute of Inorganic Chemistry, Universitätsstrasse 31, 93053 Regensburg, Germany.

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.

No MeSH data available.


Helical chains parallel to [001] (top and bottom, left) are present in the crystal structure of the tetra­gonal polymorph. Displacement ellipsoids (except for hydrogen atoms) are drawn at the 50% probability level.
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fig4: Helical chains parallel to [001] (top and bottom, left) are present in the crystal structure of the tetra­gonal polymorph. Displacement ellipsoids (except for hydrogen atoms) are drawn at the 50% probability level.

Mentions: Finally, in the tetra­gonal structure, the situation is completely different, as the ion pairs form helical chains along the 41 screw axis of space group I41cd (Fig. 4 ▶, top and bottom left). This assembly in the unit cell (Fig. 4 ▶, bottom right) results in a calculated density of 1.503 g cm−3.


About the polymorphism of [Li(C4H8O)3]I: crystal structures of trigonal and tetra-gonal polymorphs.

Gärtner S, Gärtner T, Gschwind RM, Korber N - Acta Crystallogr Sect E Struct Rep Online (2014)

Helical chains parallel to [001] (top and bottom, left) are present in the crystal structure of the tetra­gonal polymorph. Displacement ellipsoids (except for hydrogen atoms) are drawn at the 50% probability level.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4257418&req=5

fig4: Helical chains parallel to [001] (top and bottom, left) are present in the crystal structure of the tetra­gonal polymorph. Displacement ellipsoids (except for hydrogen atoms) are drawn at the 50% probability level.
Mentions: Finally, in the tetra­gonal structure, the situation is completely different, as the ion pairs form helical chains along the 41 screw axis of space group I41cd (Fig. 4 ▶, top and bottom left). This assembly in the unit cell (Fig. 4 ▶, bottom right) results in a calculated density of 1.503 g cm−3.

Bottom Line: 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.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.

View Article: PubMed Central - HTML - PubMed

Affiliation: University of Regensburg, Institute of Inorganic Chemistry, Universitätsstrasse 31, 93053 Regensburg, Germany.

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.

No MeSH data available.