Diammonium sodium hexa­fluoro­aluminate, (NH₄)₂NaAlF₆

Diammonium sodium hexa­fluoro­aluminate, (NH₄)₂NaAlF₆, obtained by hydro­thermal synthesis, comprises [AlF₆]^3- octa­hedra forming a face-centred cubic (fcc) arrangement, with Na⁺ cations filling all octa­hedral inter­stices and NH₄⁺ cations filling all tetra­hedral inter­stices.

Key indicators

• Single-crystal X-ray study
• T = 295 K
• Mean [sigma](l-F) = 0.002 Å
• R factor = 0.020
• wR factor = 0.052
• Data-to-parameter ratio = 8.0

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT066_ALERT_1_C Predicted and Reported Transmissions Identical .          ?
PLAT088_ALERT_3_C Poor Data / Parameter Ratio ....................       8.00
PLAT420_ALERT_2_C D-H Without Acceptor       N1     -   H1     ...          ?

Alert level G
REFLT03_ALERT_4_G  ALERT: MoKa measured Friedel data cannot be used to
                   determine absolute structure in a light-atom
                   study EXCEPT under VERY special conditions.
                   It is preferred that Friedel data is merged in such cases.
           From the CIF: _diffrn_reflns_theta_max           27.81
           From the CIF: _reflns_number_total                 56
           Count of symmetry unique reflns            1
           Completeness (_total/calc)           5600.00%
           TEST3: Check Friedels for noncentro structure
           Estimate of Friedel pairs measured        55
           Fraction of Friedel pairs measured    55.000
           Are heavy atom types Z>Si present         no

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   3 ALERT level C = Check and explain
   1 ALERT level G = General alerts; check

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

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Computing details

Data collection: SMART (Bruker, 2001); cell refinement: SAINT (Bruker, 2001); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: DIAMOND (Brandenburg, 2004); software used to prepare material for publication: SHELXL97.

Diammonium sodium aluminium fluoride

Crystal data

(NH4)2NaAlF6	Dx = 2.287 Mg m^−3
Mr = 400.11	Mo Kα radiation, λ = 0.71073 Å
Cubic, Fm3m	Cell parameters from 1631 reflections
Hall symbol: -F 4 2 3	θ = 4.2–27.8°
a = 8.3450 (3) Å	µ = 0.48 mm^−1
V = 581.14 (4) Å^3	T = 295 K
Z = 2	Prism, colourless
F(000) = 400	0.17 × 0.15 × 0.10 mm

Data collection

Bruker SMART CCD diffractometer	56 independent reflections
Radiation source: fine-focus sealed tube	56 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.027
ω scans	θmax = 27.8°, θmin = 4.2°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −10→10
Tmin = 0.923, Tmax = 0.954	k = −10→10
1631 measured reflections	l = −10→10

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.020	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.052	H-atom parameters constrained
S = 1.36	w = 1/[σ^2(Fo^2) + (0.0254P)^2 + 0.8143P] where P = (Fo^2 + 2Fc^2)/3
56 reflections	(Δ/σ)max < 0.001
7 parameters	Δρmax = 0.26 e Å^−3
0 restraints	Δρmin = −0.40 e Å^−3

Special details

Experimental. Fourier transform infrared (FTIR) spectrum (2 mg dispersed in 200 mg KBr; ν, cm^-1): 3286(s), 3107(w), 2920(w), 2850(w), 1433(s), 722 (w), 565(bs), 489(w), 449(w).

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

Refinement. Refinement of F² against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The threshold expression of F² > σ(F²) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F² are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

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

	x	y	z	Uiso*/Ueq
Al1	0.5000	0.5000	0.0000	0.0138 (5)
Na1	0.5000	0.5000	0.5000	0.0216 (7)
F1	0.5000	0.5000	0.21750 (19)	0.0231 (5)
N1	0.2500	0.2500	0.2500	0.0201 (9)
H1	0.1887	0.3113	0.3113	0.176*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Al1	0.0138 (5)	0.0138 (5)	0.0138 (5)	0.000	0.000	0.000
Na1	0.0216 (7)	0.0216 (7)	0.0216 (7)	0.000	0.000	0.000
F1	0.0268 (7)	0.0268 (7)	0.0156 (9)	0.000	0.000	0.000
N1	0.0201 (9)	0.0201 (9)	0.0201 (9)	0.000	0.000	0.000

Geometric parameters (Å, º)

Al1—F1^i	1.8151 (16)	F1—N1^xii	2.9628 (2)
Al1—F1^ii	1.8151 (16)	F1—N1^xiii	2.9628 (2)
Al1—F1^iii	1.8151 (16)	N1—F1^xiv	2.9628 (2)
Al1—F1^iv	1.8151 (16)	N1—F1^xv	2.9628 (2)
Al1—F1^v	1.8151 (16)	N1—F1^xvi	2.9628 (2)
Al1—F1	1.8151 (16)	N1—F1^x	2.9628 (2)
Na1—F1	2.3574 (16)	N1—F1^viii	2.9628 (2)
Na1—F1^vi	2.3574 (16)	N1—F1^xvii	2.9628 (2)
Na1—F1^vii	2.3574 (16)	N1—F1^xiii	2.9628 (2)
Na1—F1^viii	2.3574 (16)	N1—F1^xii	2.9628 (2)
Na1—F1^ix	2.3574 (16)	N1—F1^i	2.9628 (2)
Na1—F1^x	2.3574 (16)	N1—F1^xviii	2.9628 (2)
F1—N1^xi	2.9628 (2)	N1—F1^v	2.9628 (2)
F1—N1	2.9628 (2)	N1—H1	0.886
F1^i—Al1—F1^ii	180.0	F1—Na1—F1^vii	180.0
F1^i—Al1—F1^iii	90.0	F1^vi—Na1—F1^vii	90.0
F1^ii—Al1—F1^iii	90.0	F1—Na1—F1^viii	90.0
F1^i—Al1—F1^iv	90.0	F1^vi—Na1—F1^viii	90.0
F1^ii—Al1—F1^iv	90.0	F1^vii—Na1—F1^viii	90.0
F1^iii—Al1—F1^iv	90.0	F1—Na1—F1^ix	90.0
F1^i—Al1—F1^v	90.0	F1^vi—Na1—F1^ix	90.0
F1^ii—Al1—F1^v	90.0	F1^vii—Na1—F1^ix	90.0
F1^iii—Al1—F1^v	90.0	F1^viii—Na1—F1^ix	180.0
F1^iv—Al1—F1^v	180.0	F1—Na1—F1^x	90.0
F1^i—Al1—F1	90.0	F1^vi—Na1—F1^x	180.0
F1^ii—Al1—F1	90.0	F1^vii—Na1—F1^x	90.0
F1^iii—Al1—F1	180.0	F1^viii—Na1—F1^x	90.0
F1^iv—Al1—F1	90.0	F1^ix—Na1—F1^x	90.0
F1^v—Al1—F1	90.0	Al1—F1—Na1	180.0
F1—Na1—F1^vi	90.0

Symmetry codes: (i) −y+1, −z+1/2, −x+1/2; (ii) y, z+1/2, x−1/2; (iii) −x+1, −y+1, −z; (iv) z+1/2, x, y−1/2; (v) −z+1/2, −x+1, −y+1/2; (vi) −y+1, −z+1, −x+1; (vii) −x+1, −y+1, −z+1; (viii) z, x, y; (ix) −z+1, −x+1, −y+1; (x) y, z, x; (xi) x+1/2, y+1/2, z; (xii) −x+1/2, −y+1, −z+1/2; (xiii) −x+1, −y+1/2, −z+1/2; (xiv) y−1/2, z, x−1/2; (xv) z, x−1/2, y−1/2; (xvi) x−1/2, y−1/2, z; (xvii) −y+1/2, −z+1/2, −x+1; (xviii) −z+1/2, −x+1/2, −y+1.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1···F1^viii	0.89	2.24	2.9628 (2)	139

Symmetry code: (viii) z, x, y.