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

The new polymorph of lithium tetra­chlorido­aluminate, LiAlCl₄, adopts a defect wurtz-stannite-type of structure and is metastable.

Key indicators

• Single-crystal X-ray study
• T = 173 K
• Mean [sigma](Cl-Al) = 0.002 Å
• Disorder in solvent or counterion
• R factor = 0.028
• wR factor = 0.075
• Data-to-parameter ratio = 23.8

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT911_ALERT_3_C Missing # FCF Refl Between THmin & STh/L=  0.600          6 Report
PLAT913_ALERT_3_C Missing # of Very Strong Reflections in FCF ....          6 Note
PLAT934_ALERT_3_C Number of (Iobs-Icalc)/SigmaW > 10 Outliers ....          1 Check

Alert level G
PLAT004_ALERT_5_G Polymeric Structure Found with Maximum Dimension          2 Info
PLAT019_ALERT_1_G _diffrn_measured_fraction_theta_full/*_max < 1.0      0.994 Report
PLAT042_ALERT_1_G Calc. and Reported MoietyFormula Strings  Differ     Please Check
PLAT063_ALERT_4_G Crystal Size Likely too Large for Beam Size ....       0.65 mm
PLAT300_ALERT_4_G Atom Site Occupancy of Li1     is Constrained at        0.5 Check
PLAT302_ALERT_4_G Anion/Solvent/Minor-Residue Disorder (Resd  2)..       100% Note
PLAT794_ALERT_5_G Tentative Bond Valency for Al1     (III)   .....       3.00 Info

   0 ALERT level A = Most likely a serious problem - resolve or explain
   0 ALERT level B = A potentially serious problem, consider carefully
   3 ALERT level C = Check. Ensure it is not caused by an omission or oversight
   7 ALERT level G = General information/check it is not something unexpected

   2 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   0 ALERT type 2 Indicator that the structure model may be wrong or deficient
   3 ALERT type 3 Indicator that the structure quality may be low
   3 ALERT type 4 Improvement, methodology, query or suggestion
   2 ALERT type 5 Informative message, check

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Computing details

Data collection: X-AREA (Stoe & Cie, 2009); cell refinement: X-AREA (Stoe & Cie, 2009); data reduction: X-AREA (Stoe & Cie, 2009); program(s) used to solve structure: SHELXT (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015b); molecular graphics: DIAMOND (Brandenburg, 2016); software used to prepare material for publication: publCIF (Westrip, 2010).

Lithium tetrachloridoaluminate

Crystal data

LiAlCl4	Dx = 1.887 Mg m^−3
Mr = 175.72	Mo Kα radiation, λ = 0.71073 Å
Orthorhombic, Pmn21	Cell parameters from 6814 reflections
a = 7.8273 (10) Å	θ = 3.0–29.7°
b = 6.4466 (10) Å	µ = 1.90 mm^−1
c = 6.1304 (8) Å	T = 173 K
V = 309.34 (7) Å^3	Needle-shaped, colorless
Z = 2	0.65 × 0.10 × 0.03 mm
F(000) = 168

Data collection

Stoe IPDS 2T diffractometer	870 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.092
φ–scans	θmax = 29.1°, θmin = 3.2°
Absorption correction: multi-scan (X-AREA; Stoe & Cie, 2009)	h = −10→10
Tmin = 0.431, Tmax = 0.583	k = −8→8
3388 measured reflections	l = −8→8
880 independent reflections

Refinement

Refinement on F^2	1 restraint
Least-squares matrix: full	w = 1/[σ^2(Fo^2) + (0.022P)^2 + 0.166P] where P = (Fo^2 + 2Fc^2)/3
R[F^2 > 2σ(F^2)] = 0.028	(Δ/σ)max < 0.001
wR(F^2) = 0.075	Δρmax = 0.48 e Å^−3
S = 1.21	Δρmin = −0.46 e Å^−3
880 reflections	Absolute structure: Flack x determined using 386 quotients [(I+)-(I-)]/[(I+)+(I-)] (Parsons et al., 2013)
37 parameters	Absolute structure parameter: 0.1 (2)

Special details

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq	Occ. (<1)
Li1	0.246 (2)	0.1671 (19)	0.493 (3)	0.035 (3)	0.5
Cl1	0.0000	0.31452 (19)	0.34835 (19)	0.0305 (3)
Cl2	0.22483 (12)	0.18042 (11)	0.88033 (12)	0.0317 (2)
Cl3	0.5000	0.35454 (16)	0.3896 (3)	0.0295 (3)
Al1	0.0000	0.3312 (2)	−0.0004 (3)	0.0229 (3)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Li1	0.043 (8)	0.033 (6)	0.029 (8)	0.001 (6)	0.002 (6)	0.000 (4)
Cl1	0.0300 (5)	0.0405 (6)	0.0208 (7)	0.000	0.000	0.0010 (4)
Cl2	0.0313 (4)	0.0314 (4)	0.0324 (5)	0.0078 (3)	0.0067 (5)	0.0017 (5)
Cl3	0.0300 (5)	0.0226 (4)	0.0360 (6)	0.000	0.000	−0.0055 (6)
Al1	0.0244 (8)	0.0212 (6)	0.0233 (8)	0.000	0.000	0.0008 (5)

Geometric parameters (Å, º)

Li1—Cl1	2.322 (17)	Cl2—Li1^iv	2.356 (14)
Li1—Cl2^i	2.356 (14)	Cl3—Al1^v	2.1354 (18)
Li1—Cl2	2.38 (2)	Cl3—Li1^vi	2.413 (17)
Li1—Cl3	2.413 (17)	Al1—Cl3^vii	2.1354 (18)
Cl1—Al1	2.1404 (19)	Al1—Cl2^viii	2.1392 (11)
Cl1—Li1^ii	2.322 (17)	Al1—Cl2^ix	2.1392 (11)
Cl2—Al1^iii	2.1392 (11)
Cl1—Li1—Cl2^i	111.0 (7)	Li1^iv—Cl2—Li1	104.6 (5)
Cl1—Li1—Cl2	108.0 (7)	Al1^v—Cl3—Li1^vi	113.1 (4)
Cl2^i—Li1—Cl2	109.5 (6)	Al1^v—Cl3—Li1	113.1 (4)
Cl1—Li1—Cl3	112.2 (6)	Li1^vi—Cl3—Li1	111.1 (7)
Cl2^i—Li1—Cl3	108.6 (7)	Cl3^vii—Al1—Cl2^viii	108.85 (6)
Cl2—Li1—Cl3	107.5 (7)	Cl3^vii—Al1—Cl2^ix	108.85 (6)
Al1—Cl1—Li1^ii	113.7 (5)	Cl2^viii—Al1—Cl2^ix	110.70 (8)
Al1—Cl1—Li1	113.7 (5)	Cl3^vii—Al1—Cl1	111.28 (9)
Li1^ii—Cl1—Li1	111.9 (9)	Cl2^viii—Al1—Cl1	108.58 (6)
Al1^iii—Cl2—Li1^iv	114.3 (4)	Cl2^ix—Al1—Cl1	108.58 (6)
Al1^iii—Cl2—Li1	114.4 (4)

Symmetry codes: (i) −x+1/2, −y, z−1/2; (ii) −x, y, z; (iii) x, y, z+1; (iv) −x+1/2, −y, z+1/2; (v) −x+1/2, −y+1, z+1/2; (vi) −x+1, y, z; (vii) −x+1/2, −y+1, z−1/2; (viii) −x, y, z−1; (ix) x, y, z−1.