Poly[bis­(acetonitrile-κN)bis­[μ3-bis(tri­fluoro­methane­sulfonyl)­imido-κ4 O,O′:O′′:O′′′]dilithium]

Daniel M Seo; Paul D Boyle; Wesley A Henderson

doi:10.1107/S1600536811011561

. 2011 Apr 7;67(Pt 5):m534. doi: 10.1107/S1600536811011561

Poly[bis(acetonitrile-κN)bis[μ₃-bis(trifluoromethanesulfonyl)imido-κ⁴ O,O′:O′′:O′′′]dilithium]

Daniel M Seo ^a, Paul D Boyle ^b, Wesley A Henderson ^a,^*

PMCID: PMC3089180 PMID: 21754274

Abstract

In the title compound, [Li₂(CF₃SO₂NSO₂CF₃)₂(CH₃CN)₂]_n, two Li⁺ cations reside on crystallographic inversion centers, each coordinated by six O atoms from bis(trifluoromethanesulfonyl)imide (TFSI⁻) anions. The third Li⁺ cation on a general position is four-coordinated by two anion O atoms and two N atoms from acetonitrile molecules in a tetrahedral geometry.

Related literature

For the structure of LiN(SO₂CF₃)₂, see: Nowinski et al. (1994) ▶. For a related structure of LiN(SO₂CF₃)₂, see: Henderson et al. (2005 ▶); Davidson et al. (2003 ▶); Brouillette et al. (2002 ▶); Dillon et al. (2001) ▶. For the structure of CH₃CN with lithium salts, see: Klapötke et al. (2006 ▶); Brooks et al. (2002 ▶); Yokota et al. (1999) ▶; Raston et al. (1989 ▶).

Experimental

Crystal data

[Li₂(C₂F₆NO₄S₂)₂(C₂H₃N)₂]
M _r = 656.29
Monoclinic,
a = 10.8654 (2) Å
b = 11.0610 (2) Å
c = 19.1778 (3) Å
β = 90.8483 (10)°
V = 2304.58 (7) Å³
Z = 4
Cu Kα radiation
μ = 5.16 mm⁻¹
T = 110 K
0.40 × 0.20 × 0.15 mm

Data collection

Bruker–Nonius X8 APEXII diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2009 ▶) T _min = 0.232, T _max = 0.512
9937 measured reflections
3950 independent reflections
3482 reflections with I > 2σ(I)
R _int = 0.041

Refinement

R[F ² > 2σ(F ²)] = 0.041
wR(F ²) = 0.108
S = 1.07
3950 reflections
348 parameters
H-atom parameters constrained
Δρ_max = 0.66 e Å⁻³
Δρ_min = −0.49 e Å⁻³

Data collection: APEX2 (Bruker, 2009 ▶); cell refinement: SAINT (Bruker, 2009 ▶); data reduction: SAINT; program(s) used to solve structure: SIR92 (Altomare et al., 1994 ▶); program(s) used to refine structure: SHELXTL (Sheldrick, 2008 ▶); molecular graphics: ORTEP-3 (Farrugia, 1997 ▶); software used to prepare material for publication: cif2tables.py (Boyle, 2008 ▶).

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536811011561/si2342sup1.cif

e-67-0m534-sup1.cif^{(24.5KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536811011561/si2342Isup2.hkl

e-67-0m534-Isup2.hkl^{(193.6KB, hkl)}

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Acknowledgments

The authors wish to thank Dr Peter S. White and the Department of Chemistry at the University of North Carolina at Chapel Hill for use of their diffractometer. They also wish to express their gratitude to the US Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering, which fully supported this research (Award DE-SC0002169).

supplementary crystallographic information

Comment

The structure contains three symmetry independent Li⁺ cations. Two of these, Li1 and Li2, reside on crystallographic inversion centers and are each are coordinated by six O atoms from TFSI^- anions in a pseudo-octahedral coordination geometry. The third Li⁺ cation, Li3, sits at a general position and is four coordinate: two O atoms and two N atoms from acetonitrile molecules form a pseudo-tetragonal coordination geometry. There are two different TFSI^- anions which ligate the Li⁺ cations Li1 and Li2 by chelating a single lithium as well as bridging the Li1···Li2 sites. These two lithium sites are joined by two TFSI^- anions to form eight membered rings. The rings are formed using atoms {O1, O2} and {O5, O6}, while the axial coordination sites for Li1 and Li2 are occupied by O3 and O7, respectively. These rings form a polymeric chain which propagates along the [0 1 0] direction. Two of the coordination sites for the four coordinate Li3 atom are occupied by O4 and O8, thus providing a link between two TFSI^- ligands. The other two coordination sites are occupied by the N atoms from two different acetonitrile molecules. The methyl tails as well as the CF₃ groups from the TFSI^- anions form the exterior of the polymeric chains.

Experimental

LiTFSI was purchased from 3M and dried under high-vacuum at 393 K. Anhydrous acetonitrile (Sigma Aldrich, 99.8%) was used as-received. In a vacuum atmospheres (N₂) glove box (< 5 p.p.m. H₂O), LiTFSI (5 mmol) and acetonitrile (6 mmol) were sealed in a vial and the mixture heated on a hot plate to form a homogeneous solution. 2 ml of toluene was then added to the vial to dilute the mixture. Upon standing at 278 K in a refrigerator, colorless plate single crystals formed suitable for analysis.