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The multicomponent alumosilicide Li
12Mg
3Si
3Al (cubic, space group
I3
d,
cI76) belongs to the structural family based on the Cu
15Si
4 type. The Li atoms are ordered and occupy the site with symmetry 1 and the Mg atoms occupy the site with
.. symmetry. The Si/Al statistical mixture occupies the site with .3. symmetry. The coordination polyhedra around the Li atoms are 13-vertex distorted pseudo-Frank–Kasper polyhedra. The environments of the Mg and Si/Al atoms are icosahedral. The hydrogen storage characteristics of Li
12Mg
3Si
3Al were investigated. The reversible hydrogen storage capacity of the title compound is excellent and the gravimetric storage capacity of this new material, corresponding to 9.1 wt% H
2, is higher compared to Li
12Mg
3Si
4 (8.8 wt%). The enthalpy of hydrogen desorption is 86 kJ mol
−1 and is lower compared to known lithium-based hydrides.
Supporting information
CCDC reference: 2078493
Data collection: CrysAlis CCD (Oxford Diffraction, 2008); cell refinement: CrysAlis CCD (Oxford Diffraction, 2008); data reduction: CrysAlis RED (Oxford Diffraction, 2008); program(s) used to solve structure: SHELXS2014 (Sheldrick, 2008); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015); molecular graphics: DIAMOND (Brandenburg, 2006); software used to prepare material for publication: SHELXL2014 (Sheldrick, 2015).
Dodecalithium trimagnesium trisilicon aluminium
top
Crystal data top
Li12Mg3Si3Al | Mo Kα radiation, λ = 0.71073 Å |
Mr = 89.16 | Cell parameters from 217 reflections |
Cubic, I43d | θ = 4.7–25.2° |
a = 10.7338 (9) Å | µ = 0.54 mm−1 |
V = 1236.7 (3) Å3 | T = 293 K |
Z = 12 | Prism, metallic grey |
F(000) = 508 | 0.05 × 0.03 × 0.02 mm |
Dx = 1.437 Mg m−3 Dm = 1.45 (3) Mg m−3 Dm measured by volumetric | |
Data collection top
Oxford Diffraction Xcalibur3 CCD diffractometer | 217 reflections with I > 2σ(I) |
Radiation source: fine-focus sealed tube | Rint = 0.056 |
ω scans | θmax = 27.2°, θmin = 4.7° |
Absorption correction: analytical (CrysAlis RED; Oxford Diffraction, 2008) | h = −13→13 |
Tmin = 0.945, Tmax = 0.989 | k = −13→13 |
2454 measured reflections | l = −13→13 |
230 independent reflections | |
Refinement top
Refinement on F2 | 0 restraints |
Least-squares matrix: full | w = 1/[σ2(Fo2)] where P = (Fo2 + 2Fc2)/3 |
R[F2 > 2σ(F2)] = 0.018 | (Δ/σ)max = 0.002 |
wR(F2) = 0.035 | Δρmax = 0.20 e Å−3 |
S = 1.02 | Δρmin = −0.10 e Å−3 |
230 reflections | Absolute structure: Flack x determined using 87 quotients [(I+)-(I-)]/[(I+)+(I-)]
(Parsons et al., 2013) |
16 parameters | Absolute structure parameter: 0.7 (2) |
Special details top
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. |
Refinement. The structure of the title phase was solved by direct methods by means
SHELXS2014/7 package program (Sheldrick, 2008). The structure
refinements was conducted by means SHELXL2014/7 (Sheldrick, 2015). |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top | x | y | z | Uiso*/Ueq | Occ. (<1) |
Si | 0.21048 (5) | 0.21048 (5) | 0.21048 (5) | 0.0489 (2) | 0.7525 |
Al | 0.21048 (5) | 0.21048 (5) | 0.21048 (5) | 0.0489 (2) | 0.2475 |
Mg | 0.3750 | 0.0000 | 0.2500 | 0.0507 (3) | |
Li | 0.0450 (3) | 0.3867 (3) | 0.1482 (3) | 0.0512 (7) | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
Si | 0.0489 (2) | 0.0489 (2) | 0.0489 (2) | 0.0000 (2) | 0.0000 (2) | 0.0000 (2) |
Al | 0.0489 (2) | 0.0489 (2) | 0.0489 (2) | 0.0000 (2) | 0.0000 (2) | 0.0000 (2) |
Mg | 0.0511 (7) | 0.0504 (5) | 0.0504 (5) | 0.000 | 0.000 | 0.000 |
Li | 0.0507 (16) | 0.0534 (16) | 0.0495 (17) | 0.0000 (12) | −0.0016 (13) | 0.0007 (14) |
Geometric parameters (Å, º) top
Si—Lii | 2.599 (3) | Mg—Lixi | 2.883 (3) |
Si—Liii | 2.599 (3) | Mg—Lixii | 2.883 (3) |
Si—Liiii | 2.599 (3) | Mg—Liv | 2.883 (3) |
Si—Li | 2.679 (3) | Mg—Ali | 2.8987 (2) |
Si—Liiv | 2.679 (3) | Mg—Sii | 2.8987 (2) |
Si—Liv | 2.679 (3) | Mg—Alxiii | 2.8987 (2) |
Si—Mg | 2.8987 (2) | Mg—Sixiii | 2.8987 (2) |
Si—Mgiv | 2.8987 (2) | Li—Alxiv | 2.599 (3) |
Si—Mgv | 2.8987 (2) | Li—Sixiv | 2.599 (3) |
Si—Livi | 3.009 (3) | Li—Lixv | 2.707 (5) |
Si—Livii | 3.009 (3) | Li—Lixvi | 2.707 (5) |
Si—Liviii | 3.009 (3) | Li—Mgv | 2.718 (3) |
Mg—Liix | 2.718 (3) | Li—Lixvii | 2.880 (5) |
Mg—Lii | 2.718 (3) | Li—Liiii | 2.880 (5) |
Mg—Lix | 2.718 (3) | Li—Mgiv | 2.883 (3) |
Mg—Liiv | 2.718 (3) | Li—Alvi | 3.009 (3) |
Mg—Livii | 2.883 (3) | Li—Sivi | 3.009 (3) |
| | | |
Lii—Si—Liii | 62.77 (11) | Liix—Mg—Ali | 127.07 (6) |
Lii—Si—Liiii | 62.77 (11) | Lii—Mg—Ali | 56.87 (6) |
Liii—Si—Liiii | 62.77 (11) | Lix—Mg—Ali | 55.02 (6) |
Lii—Si—Li | 128.88 (11) | Liiv—Mg—Ali | 121.14 (6) |
Liii—Si—Li | 93.60 (9) | Livii—Mg—Ali | 159.32 (6) |
Liiii—Si—Li | 66.11 (11) | Lixi—Mg—Ali | 62.72 (6) |
Lii—Si—Liiv | 93.60 (9) | Lixii—Mg—Ali | 55.21 (6) |
Liii—Si—Liiv | 66.11 (11) | Liv—Mg—Ali | 95.35 (6) |
Liiii—Si—Liiv | 128.88 (11) | Liix—Mg—Sii | 127.07 (6) |
Li—Si—Liiv | 118.60 (2) | Lii—Mg—Sii | 56.87 (6) |
Lii—Si—Liv | 66.11 (11) | Lix—Mg—Sii | 55.02 (6) |
Liii—Si—Liv | 128.88 (11) | Liiv—Mg—Sii | 121.14 (6) |
Liiii—Si—Liv | 93.60 (9) | Livii—Mg—Sii | 159.32 (6) |
Li—Si—Liv | 118.60 (2) | Lixi—Mg—Sii | 62.72 (6) |
Liiv—Si—Liv | 118.60 (2) | Lixii—Mg—Sii | 55.21 (6) |
Lii—Si—Mg | 58.96 (7) | Liv—Mg—Sii | 95.35 (6) |
Liii—Si—Mg | 91.31 (7) | Ali—Mg—Sii | 0.0 |
Liiii—Si—Mg | 121.71 (7) | Liix—Mg—Alxiii | 55.02 (6) |
Li—Si—Mg | 172.12 (7) | Lii—Mg—Alxiii | 121.14 (6) |
Liiv—Si—Mg | 58.17 (7) | Lix—Mg—Alxiii | 56.87 (6) |
Liv—Si—Mg | 62.09 (7) | Liiv—Mg—Alxiii | 127.07 (6) |
Lii—Si—Mgiv | 91.31 (7) | Livii—Mg—Alxiii | 55.21 (6) |
Liii—Si—Mgiv | 121.71 (7) | Lixi—Mg—Alxiii | 159.32 (6) |
Liiii—Si—Mgiv | 58.96 (7) | Lixii—Mg—Alxiii | 95.35 (6) |
Li—Si—Mgiv | 62.09 (7) | Liv—Mg—Alxiii | 62.72 (6) |
Liiv—Si—Mgiv | 172.12 (7) | Ali—Mg—Alxiii | 111.787 (14) |
Liv—Si—Mgiv | 58.17 (7) | Sii—Mg—Alxiii | 111.787 (14) |
Mg—Si—Mgiv | 119.981 (1) | Liix—Mg—Sixiii | 55.02 (6) |
Lii—Si—Mgv | 121.71 (7) | Lii—Mg—Sixiii | 121.14 (6) |
Liii—Si—Mgv | 58.96 (7) | Lix—Mg—Sixiii | 56.87 (6) |
Liiii—Si—Mgv | 91.31 (7) | Liiv—Mg—Sixiii | 127.07 (6) |
Li—Si—Mgv | 58.17 (7) | Livii—Mg—Sixiii | 55.21 (6) |
Liiv—Si—Mgv | 62.09 (7) | Lixi—Mg—Sixiii | 159.32 (6) |
Liv—Si—Mgv | 172.12 (7) | Lixii—Mg—Sixiii | 95.35 (6) |
Mg—Si—Mgv | 119.981 (1) | Liv—Mg—Sixiii | 62.72 (6) |
Mgiv—Si—Mgv | 119.981 (1) | Ali—Mg—Sixiii | 111.8 |
Lii—Si—Livi | 137.69 (11) | Sii—Mg—Sixiii | 111.787 (14) |
Liii—Si—Livi | 156.97 (12) | Alxiii—Mg—Sixiii | 0.0 |
Liiii—Si—Livi | 112.85 (10) | Alxiv—Li—Sixiv | 0.0 |
Li—Si—Livi | 65.49 (10) | Alxiv—Li—Si | 130.8 |
Liiv—Si—Livi | 114.19 (9) | Sixiv—Li—Si | 130.84 (13) |
Liv—Si—Livi | 72.53 (2) | Alxiv—Li—Lixv | 58.61 (6) |
Mg—Si—Livi | 108.52 (6) | Sixiv—Li—Lixv | 58.61 (6) |
Mgiv—Si—Livi | 58.38 (6) | Si—Li—Lixv | 120.63 (16) |
Mgv—Si—Livi | 99.87 (6) | Alxiv—Li—Lixvi | 58.61 (6) |
Lii—Si—Livii | 112.85 (10) | Sixiv—Li—Lixvi | 58.61 (6) |
Liii—Si—Livii | 137.69 (11) | Si—Li—Lixvi | 170.22 (7) |
Liiii—Si—Livii | 156.97 (12) | Lixv—Li—Lixvi | 60.0 |
Li—Si—Livii | 114.19 (9) | Alxiv—Li—Mgv | 66.02 (8) |
Liiv—Si—Livii | 72.525 (19) | Sixiv—Li—Mgv | 66.02 (8) |
Liv—Si—Livii | 65.49 (10) | Si—Li—Mgv | 64.96 (7) |
Mg—Si—Livii | 58.38 (6) | Lixv—Li—Mgv | 93.06 (11) |
Mgiv—Si—Livii | 99.87 (6) | Lixvi—Li—Mgv | 124.62 (6) |
Mgv—Si—Livii | 108.52 (6) | Alxiv—Li—Lixvii | 58.28 (10) |
Livi—Si—Livii | 53.47 (9) | Sixiv—Li—Lixvii | 58.28 (10) |
Lii—Si—Liviii | 156.97 (12) | Si—Li—Lixvii | 100.45 (15) |
Liii—Si—Liviii | 112.85 (10) | Lixv—Li—Lixvii | 116.89 (11) |
Liiii—Si—Liviii | 137.69 (11) | Lixvi—Li—Lixvii | 87.00 (16) |
Li—Si—Liviii | 72.525 (19) | Mgv—Li—Lixvii | 61.91 (13) |
Liiv—Si—Liviii | 65.49 (10) | Alxiv—Li—Liiii | 127.44 (13) |
Liv—Si—Liviii | 114.19 (9) | Sixiv—Li—Liiii | 127.44 (13) |
Mg—Si—Liviii | 99.87 (6) | Si—Li—Liiii | 55.61 (11) |
Mgiv—Si—Liviii | 108.52 (6) | Lixv—Li—Liiii | 173.89 (9) |
Mgv—Si—Liviii | 58.38 (6) | Lixvi—Li—Liiii | 122.74 (18) |
Livi—Si—Liviii | 53.47 (9) | Mgv—Li—Liiii | 89.34 (14) |
Livii—Si—Liviii | 53.47 (9) | Lixvii—Li—Liiii | 69.17 (12) |
Liix—Mg—Lii | 174.71 (12) | Alxiv—Li—Mgiv | 166.42 (14) |
Liix—Mg—Lix | 90.122 (6) | Sixiv—Li—Mgiv | 166.42 (14) |
Lii—Mg—Lix | 90.122 (6) | Si—Li—Mgiv | 62.69 (6) |
Liix—Mg—Liiv | 90.122 (6) | Lixv—Li—Mgiv | 118.11 (6) |
Lii—Mg—Liiv | 90.122 (6) | Lixvi—Li—Mgiv | 107.93 (10) |
Lix—Mg—Liiv | 174.71 (12) | Mgv—Li—Mgiv | 127.33 (11) |
Liix—Mg—Livii | 61.80 (10) | Lixvii—Li—Mgiv | 122.97 (10) |
Lii—Mg—Livii | 113.24 (8) | Liiii—Li—Mgiv | 56.29 (10) |
Lix—Mg—Livii | 110.66 (11) | Alxiv—Li—Alvi | 111.73 (10) |
Liiv—Mg—Livii | 74.04 (6) | Sixiv—Li—Alvi | 111.73 (10) |
Liix—Mg—Lixi | 110.66 (11) | Si—Li—Alvi | 107.7 |
Lii—Mg—Lixi | 74.04 (6) | Lixv—Li—Alvi | 63.26 (5) |
Lix—Mg—Lixi | 113.24 (8) | Lixvi—Li—Alvi | 63.26 (5) |
Liiv—Mg—Lixi | 61.80 (10) | Mgv—Li—Alvi | 148.40 (11) |
Livii—Mg—Lixi | 135.47 (7) | Lixvii—Li—Alvi | 146.18 (16) |
Liix—Mg—Lixii | 74.04 (6) | Liiii—Li—Alvi | 112.35 (14) |
Lii—Mg—Lixii | 110.66 (11) | Mgiv—Li—Alvi | 58.89 (6) |
Lix—Mg—Lixii | 61.80 (10) | Alxiv—Li—Sivi | 111.7 |
Liiv—Mg—Lixii | 113.24 (8) | Sixiv—Li—Sivi | 111.73 (10) |
Livii—Mg—Lixii | 135.47 (7) | Si—Li—Sivi | 107.70 (10) |
Lixi—Mg—Lixii | 64.80 (11) | Lixv—Li—Sivi | 63.26 (5) |
Liix—Mg—Liv | 113.24 (8) | Lixvi—Li—Sivi | 63.26 (5) |
Lii—Mg—Liv | 61.80 (10) | Mgv—Li—Sivi | 148.40 (11) |
Lix—Mg—Liv | 74.04 (6) | Lixvii—Li—Sivi | 146.18 (16) |
Liiv—Mg—Liv | 110.66 (11) | Liiii—Li—Sivi | 112.35 (14) |
Livii—Mg—Liv | 64.80 (11) | Mgiv—Li—Sivi | 58.89 (6) |
Lixi—Mg—Liv | 135.47 (7) | Alvi—Li—Sivi | 0.0 |
Lixii—Mg—Liv | 135.47 (7) | | |
Symmetry codes: (i) −y+3/4, −x+1/4, z+1/4; (ii) z+1/4, −y+3/4, −x+1/4; (iii) −x+1/4, z+1/4, −y+3/4; (iv) y, z, x; (v) z, x, y; (vi) −x, −y+1/2, z; (vii) z, −x, −y+1/2; (viii) −y+1/2, z, −x; (ix) −y+3/4, x−1/4, −z+1/4; (x) y, −z, −x+1/2; (xi) −z+3/4, y−1/4, −x+1/4; (xii) −z+3/4, −y+1/4, x+1/4; (xiii) x, −y, −z+1/2; (xiv) −y+1/4, −x+3/4, z−1/4; (xv) y−1/2, −z+1/2, −x; (xvi) −z, x+1/2, −y+1/2; (xvii) −x+1/4, −z+3/4, y−1/4. |
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