Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S160053680705413X/wm2155sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S160053680705413X/wm2155Isup2.hkl |
Key indicators
- Single-crystal X-ray study
- T = 293 K
- Mean () = 0.000 Å
- R factor = 0.035
- wR factor = 0.088
- Data-to-parameter ratio = 25.6
checkCIF/PLATON results
No syntax errors found
Alert level C ABSTM02_ALERT_3_C The ratio of expected to reported Tmax/Tmin(RR) is > 1.10 Tmin and Tmax reported: 0.276 0.431 Tmin and Tmax expected: 0.243 0.431 RR = 1.135 Please check that your absorption correction is appropriate. STRVA01_ALERT_4_C Flack test results are ambiguous. From the CIF: _refine_ls_abs_structure_Flack 0.430 From the CIF: _refine_ls_abs_structure_Flack_su 0.050 PLAT041_ALERT_1_C Calc. and Rep. SumFormula Strings Differ .... ? PLAT045_ALERT_1_C Calculated and Reported Z Differ by ............ 0.33 Ratio PLAT060_ALERT_3_C Ratio Tmax/Tmin (Exp-to-Rep) (too) Large ....... 1.13 PLAT731_ALERT_1_C Bond Calc 3.487(2), Rep 3.4869(8) ...... 2.50 su-Ra Y1 -MG1 1.555 2.775 PLAT731_ALERT_1_C Bond Calc 3.487(3), Rep 3.4868(8) ...... 3.75 su-Ra Y1 -MG1 1.555 3.564 PLAT731_ALERT_1_C Bond Calc 3.487(3), Rep 3.4868(8) ...... 3.75 su-Ra Y1 -MG1 1.555 3.565 PLAT731_ALERT_1_C Bond Calc 3.487(2), Rep 3.4868(8) ...... 2.50 su-Ra Y1 -MG1 1.555 2.774 PLAT731_ALERT_1_C Bond Calc 3.0936(10), Rep 3.0936(4) ...... 2.50 su-Ra GA1 -Y1 1.555 3.565 PLAT731_ALERT_1_C Bond Calc 3.0936(10), Rep 3.0936(4) ...... 2.50 su-Ra GA1 -Y1 1.555 3.566
Alert level G REFLT03_ALERT_4_G Please check that the estimate of the number of Friedel pairs is correct. If it is not, please give the correct count in the _publ_section_exptl_refinement section of the submitted CIF. From the CIF: _diffrn_reflns_theta_max 26.27 From the CIF: _reflns_number_total 333 Count of symmetry unique reflns 199 Completeness (_total/calc) 167.34% TEST3: Check Friedels for noncentro structure Estimate of Friedel pairs measured 134 Fraction of Friedel pairs measured 0.673 Are heavy atom types Z>Si present yes PLAT033_ALERT_2_G Flack Parameter Value Deviates 2 * su from zero. 0.43 PLAT199_ALERT_1_G Check the Reported _cell_measurement_temperature 293 K PLAT200_ALERT_1_G Check the Reported _diffrn_ambient_temperature . 293 K
0 ALERT level A = In general: serious problem 0 ALERT level B = Potentially serious problem 11 ALERT level C = Check and explain 4 ALERT level G = General alerts; check 10 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 2 ALERT type 3 Indicator that the structure quality may be low 2 ALERT type 4 Improvement, methodology, query or suggestion 0 ALERT type 5 Informative message, check
For structure refinement of LaMgGa and for the unit-cell parameters of YMgGa, see: Kraft et al. (2003). The crystal structure of YMgGa is related to the Fe2P type structure (Rundqvist & Jellinek, 1959). For structural investigations of Mg and binaries in the Y–Mg–Ga system, see: Smith et al. (1969); Owen et al. (1935); Smith et al. (1965); Schob & Parthé, (1965). For Mg alloys and hydrogen-absorbing properties of Mg compounds, see: Sakintuna et al. (2007); Zlotea et al. (2006); Sahlberg & Andersson (2007).
YMgGa single crystals were obtained by heating appropriate amounts of the elements (Mg 99.95%, Y 99.9%, Ga 99.998%) inside an argon filled sealed tantalum tube in a high-frequency induction furnace at 1373 K. The sample was then heat-treated at 573 K for seven d to improve crystal growth. Large single crystals were removed from the surface of the sample and cut into smaller pieces. Bulk samples were characterized by X-ray powder diffraction.
The highest peak in the final Fourier map is located is 1.05 Å, and the deepest hole 1.51 Å from Y1. The measured crystal was an inversion twin with an approximate twin ratio of 1:1 (Flack parameter 0.43 (5).
Data collection: SMART (Bruker, 2001); cell refinement: SAINT (Bruker, 2001); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2001); program(s) used to refine structure: SHELXTL; molecular graphics: DIAMOND (Crystal Impact, 2006); software used to prepare material for publication: SHELXTL and publCIF (Westrip, 2007).
YMgGa | Dx = 4.505 Mg m−3 |
Mr = 182.94 | Ag Kα radiation, λ = 0.56085 Å |
Hexagonal, P62m | Cell parameters from 801 reflections |
Hall symbol: P -6 -2 | θ = 3.6–22.4° |
a = 7.2689 (10) Å | µ = 16.83 mm−1 |
c = 4.4205 (9) Å | T = 293 K |
V = 202.27 (6) Å3 | Block, grey |
Z = 3 | 0.09 × 0.07 × 0.05 mm |
F(000) = 246 |
Bruker Apex1 diffractometer | 333 independent reflections |
Radiation source: fine-focus sealed tube | 324 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.087 |
Detector resolution: 7.31 pixels mm-1 | θmax = 26.3°, θmin = 2.6° |
ω–scans | h = −11→11 |
Absorption correction: multi-scan (SADABS; Sheldrick, 2001) | k = −11→11 |
Tmin = 0.276, Tmax = 0.431 | l = −6→6 |
4365 measured reflections |
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.035 | w = 1/[σ2(Fo2) + (0.0466P)2 + 0.5229P] where P = (Fo2 + 2Fc2)/3 |
wR(F2) = 0.088 | (Δ/σ)max = 0.001 |
S = 1.15 | Δρmax = 1.65 e Å−3 |
333 reflections | Δρmin = −1.78 e Å−3 |
13 parameters | Absolute structure: Flack (1983), 136 Friedel pairs |
0 restraints | Absolute structure parameter: 0.43 (5) |
YMgGa | Z = 3 |
Mr = 182.94 | Ag Kα radiation, λ = 0.56085 Å |
Hexagonal, P62m | µ = 16.83 mm−1 |
a = 7.2689 (10) Å | T = 293 K |
c = 4.4205 (9) Å | 0.09 × 0.07 × 0.05 mm |
V = 202.27 (6) Å3 |
Bruker Apex1 diffractometer | 333 independent reflections |
Absorption correction: multi-scan (SADABS; Sheldrick, 2001) | 324 reflections with I > 2σ(I) |
Tmin = 0.276, Tmax = 0.431 | Rint = 0.087 |
4365 measured reflections |
R[F2 > 2σ(F2)] = 0.035 | 0 restraints |
wR(F2) = 0.088 | Δρmax = 1.65 e Å−3 |
S = 1.15 | Δρmin = −1.78 e Å−3 |
333 reflections | Absolute structure: Flack (1983), 136 Friedel pairs |
13 parameters | Absolute structure parameter: 0.43 (5) |
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. |
x | y | z | Uiso*/Ueq | ||
Y1 | 0.57308 (15) | 1.0000 | 0.5000 | 0.0116 (2) | |
Ga1 | 0.3333 | 0.6667 | 1.0000 | 0.0104 (3) | |
Ga2 | 0.0000 | 1.0000 | 0.5000 | 0.0125 (4) | |
Mg1 | 0.2443 (5) | 1.0000 | 1.0000 | 0.0109 (7) |
U11 | U22 | U33 | U12 | U13 | U23 | |
Y1 | 0.0118 (3) | 0.0103 (4) | 0.0121 (4) | 0.0052 (2) | 0.000 | 0.000 |
Ga1 | 0.0101 (4) | 0.0101 (4) | 0.0112 (6) | 0.0050 (2) | 0.000 | 0.000 |
Ga2 | 0.0138 (6) | 0.0138 (6) | 0.0100 (9) | 0.0069 (3) | 0.000 | 0.000 |
Mg1 | 0.0088 (14) | 0.0102 (19) | 0.0141 (17) | 0.0051 (9) | 0.000 | 0.000 |
Y1—Ga1i | 3.0936 (4) | Ga1—Y1xii | 3.0936 (4) |
Y1—Ga1ii | 3.0936 (4) | Ga2—Mg1xiii | 2.835 (3) |
Y1—Ga1iii | 3.0936 (4) | Ga2—Mg1 | 2.835 (3) |
Y1—Ga1 | 3.0936 (4) | Ga2—Mg1xiv | 2.835 (3) |
Y1—Ga2iv | 3.1033 (12) | Ga2—Mg1xv | 2.835 (3) |
Y1—Mg1ii | 3.255 (3) | Ga2—Mg1ii | 2.835 (3) |
Y1—Mg1 | 3.255 (3) | Ga2—Mg1xvi | 2.835 (3) |
Y1—Mg1v | 3.4869 (8) | Ga2—Y1xvii | 3.1033 (12) |
Y1—Mg1vi | 3.4868 (8) | Ga2—Y1ix | 3.1033 (12) |
Y1—Mg1vii | 3.4868 (8) | Ga2—Y1xviii | 3.1033 (12) |
Y1—Mg1viii | 3.4868 (8) | Mg1—Ga1i | 2.803 (3) |
Y1—Y1v | 3.7491 (7) | Mg1—Ga2x | 2.835 (2) |
Ga1—Mg1 | 2.803 (3) | Mg1—Mg1xvi | 3.076 (7) |
Ga1—Mg1ix | 2.803 (3) | Mg1—Mg1xiv | 3.076 (7) |
Ga1—Mg1vii | 2.803 (3) | Mg1—Y1x | 3.255 (3) |
Ga1—Y1x | 3.0936 (4) | Mg1—Y1ix | 3.4869 (8) |
Ga1—Y1ix | 3.0936 (4) | Mg1—Y1xix | 3.4869 (8) |
Ga1—Y1xi | 3.0936 (4) | Mg1—Y1xi | 3.4868 (8) |
Ga1—Y1vii | 3.0936 (4) | Mg1—Y1xvii | 3.4868 (8) |
Ga1i—Y1—Ga1ii | 160.23 (4) | Mg1xiii—Ga2—Mg1 | 143.50 (5) |
Ga1i—Y1—Ga1iii | 91.197 (16) | Mg1xiii—Ga2—Mg1xiv | 143.50 (5) |
Ga1ii—Y1—Ga1iii | 85.420 (15) | Mg1—Ga2—Mg1xiv | 65.69 (10) |
Ga1i—Y1—Ga1 | 85.420 (15) | Mg1xiii—Ga2—Mg1xv | 65.69 (10) |
Ga1ii—Y1—Ga1 | 91.197 (16) | Mg1—Ga2—Mg1xv | 143.50 (5) |
Ga1iii—Y1—Ga1 | 160.23 (4) | Mg1xiv—Ga2—Mg1xv | 102.44 (13) |
Ga1i—Y1—Ga2iv | 99.89 (2) | Mg1xiii—Ga2—Mg1ii | 65.69 (10) |
Ga1ii—Y1—Ga2iv | 99.89 (2) | Mg1—Ga2—Mg1ii | 102.44 (13) |
Ga1iii—Y1—Ga2iv | 99.89 (2) | Mg1xiv—Ga2—Mg1ii | 143.50 (5) |
Ga1—Y1—Ga2iv | 99.89 (2) | Mg1xv—Ga2—Mg1ii | 65.69 (10) |
Ga1i—Y1—Mg1ii | 111.04 (4) | Mg1xiii—Ga2—Mg1xvi | 102.44 (13) |
Ga1ii—Y1—Mg1ii | 52.33 (3) | Mg1—Ga2—Mg1xvi | 65.69 (10) |
Ga1iii—Y1—Mg1ii | 52.33 (3) | Mg1xiv—Ga2—Mg1xvi | 65.69 (10) |
Ga1—Y1—Mg1ii | 111.04 (4) | Mg1xv—Ga2—Mg1xvi | 143.50 (5) |
Ga2iv—Y1—Mg1ii | 137.24 (5) | Mg1ii—Ga2—Mg1xvi | 143.50 (5) |
Ga1i—Y1—Mg1 | 52.33 (3) | Mg1xiii—Ga2—Y1xvii | 128.78 (6) |
Ga1ii—Y1—Mg1 | 111.04 (4) | Mg1—Ga2—Y1xvii | 71.75 (3) |
Ga1iii—Y1—Mg1 | 111.04 (4) | Mg1xiv—Ga2—Y1xvii | 71.75 (3) |
Ga1—Y1—Mg1 | 52.33 (3) | Mg1xv—Ga2—Y1xvii | 71.75 (3) |
Ga2iv—Y1—Mg1 | 137.24 (5) | Mg1ii—Ga2—Y1xvii | 71.75 (3) |
Mg1ii—Y1—Mg1 | 85.53 (10) | Mg1xvi—Ga2—Y1xvii | 128.78 (6) |
Ga1i—Y1—Mg1v | 49.99 (5) | Mg1xiii—Ga2—Y1ix | 71.75 (3) |
Ga1ii—Y1—Mg1v | 149.44 (7) | Mg1—Ga2—Y1ix | 71.75 (3) |
Ga1iii—Y1—Mg1v | 105.24 (5) | Mg1xiv—Ga2—Y1ix | 128.78 (6) |
Ga1—Y1—Mg1v | 87.44 (4) | Mg1xv—Ga2—Y1ix | 128.78 (6) |
Ga2iv—Y1—Mg1v | 50.55 (5) | Mg1ii—Ga2—Y1ix | 71.75 (3) |
Mg1ii—Y1—Mg1v | 153.75 (6) | Mg1xvi—Ga2—Y1ix | 71.75 (3) |
Mg1—Y1—Mg1v | 92.07 (7) | Y1xvii—Ga2—Y1ix | 120.0 |
Ga1i—Y1—Mg1vi | 149.44 (7) | Mg1xiii—Ga2—Y1xviii | 71.75 (3) |
Ga1ii—Y1—Mg1vi | 49.99 (5) | Mg1—Ga2—Y1xviii | 128.78 (6) |
Ga1iii—Y1—Mg1vi | 87.44 (4) | Mg1xiv—Ga2—Y1xviii | 71.75 (3) |
Ga1—Y1—Mg1vi | 105.24 (5) | Mg1xv—Ga2—Y1xviii | 71.75 (3) |
Ga2iv—Y1—Mg1vi | 50.55 (5) | Mg1ii—Ga2—Y1xviii | 128.78 (6) |
Mg1ii—Y1—Mg1vi | 92.07 (7) | Mg1xvi—Ga2—Y1xviii | 71.75 (3) |
Mg1—Y1—Mg1vi | 153.75 (6) | Y1xvii—Ga2—Y1xviii | 120.0 |
Mg1v—Y1—Mg1vi | 101.11 (10) | Y1ix—Ga2—Y1xviii | 120.0 |
Ga1i—Y1—Mg1vii | 87.44 (4) | Ga1—Mg1—Ga1i | 96.93 (12) |
Ga1ii—Y1—Mg1vii | 105.24 (5) | Ga1—Mg1—Ga2 | 114.538 (6) |
Ga1iii—Y1—Mg1vii | 149.44 (7) | Ga1i—Mg1—Ga2 | 114.538 (6) |
Ga1—Y1—Mg1vii | 49.99 (5) | Ga1—Mg1—Ga2x | 114.538 (6) |
Ga2iv—Y1—Mg1vii | 50.55 (5) | Ga1i—Mg1—Ga2x | 114.538 (6) |
Mg1ii—Y1—Mg1vii | 153.75 (6) | Ga2—Mg1—Ga2x | 102.44 (12) |
Mg1—Y1—Mg1vii | 92.07 (7) | Ga1—Mg1—Mg1xvi | 101.54 (6) |
Mg1v—Y1—Mg1vii | 52.34 (12) | Ga1i—Mg1—Mg1xvi | 161.54 (6) |
Mg1vi—Y1—Mg1vii | 78.67 (2) | Ga2—Mg1—Mg1xvi | 57.15 (5) |
Ga1i—Y1—Mg1viii | 105.24 (5) | Ga2x—Mg1—Mg1xvi | 57.15 (5) |
Ga1ii—Y1—Mg1viii | 87.44 (4) | Ga1—Mg1—Mg1xiv | 161.54 (6) |
Ga1iii—Y1—Mg1viii | 49.99 (5) | Ga1i—Mg1—Mg1xiv | 101.54 (6) |
Ga1—Y1—Mg1viii | 149.44 (7) | Ga2—Mg1—Mg1xiv | 57.15 (5) |
Ga2iv—Y1—Mg1viii | 50.55 (5) | Ga2x—Mg1—Mg1xiv | 57.15 (5) |
Mg1ii—Y1—Mg1viii | 92.07 (7) | Mg1xvi—Mg1—Mg1xiv | 60.0 |
Mg1—Y1—Mg1viii | 153.75 (6) | Ga1—Mg1—Y1x | 60.87 (6) |
Mg1v—Y1—Mg1viii | 78.67 (2) | Ga1i—Mg1—Y1x | 60.87 (6) |
Mg1vi—Y1—Mg1viii | 52.34 (12) | Ga2—Mg1—Y1x | 171.54 (11) |
Mg1vii—Y1—Mg1viii | 101.11 (10) | Ga2x—Mg1—Y1x | 86.01 (3) |
Ga1i—Y1—Y1v | 52.703 (6) | Mg1xvi—Mg1—Y1x | 129.48 (4) |
Ga1ii—Y1—Y1v | 134.380 (9) | Mg1xiv—Mg1—Y1x | 129.48 (4) |
Ga1iii—Y1—Y1v | 52.703 (6) | Ga1—Mg1—Y1 | 60.87 (6) |
Ga1—Y1—Y1v | 134.380 (9) | Ga1i—Mg1—Y1 | 60.87 (6) |
Ga2iv—Y1—Y1v | 74.21 (3) | Ga2—Mg1—Y1 | 86.01 (3) |
Mg1ii—Y1—Y1v | 101.53 (2) | Ga2x—Mg1—Y1 | 171.54 (11) |
Mg1—Y1—Y1v | 101.53 (2) | Mg1xvi—Mg1—Y1 | 129.48 (4) |
Mg1v—Y1—Y1v | 53.32 (5) | Mg1xiv—Mg1—Y1 | 129.48 (4) |
Mg1vi—Y1—Y1v | 104.56 (7) | Y1x—Mg1—Y1 | 85.53 (10) |
Mg1vii—Y1—Y1v | 104.56 (7) | Ga1—Mg1—Y1ix | 57.70 (2) |
Mg1viii—Y1—Y1v | 53.32 (5) | Ga1i—Mg1—Y1ix | 128.28 (9) |
Mg1—Ga1—Mg1ix | 120.0 | Ga2—Mg1—Y1ix | 57.70 (3) |
Mg1—Ga1—Mg1vii | 120.000 (1) | Ga2x—Mg1—Y1ix | 117.00 (8) |
Mg1ix—Ga1—Mg1vii | 120.0 | Mg1xvi—Mg1—Y1ix | 63.83 (6) |
Mg1—Ga1—Y1x | 66.80 (4) | Mg1xiv—Mg1—Y1ix | 109.25 (6) |
Mg1ix—Ga1—Y1x | 134.247 (10) | Y1x—Mg1—Y1ix | 118.53 (8) |
Mg1vii—Ga1—Y1x | 72.31 (4) | Y1—Mg1—Y1ix | 67.47 (3) |
Mg1—Ga1—Y1ix | 72.31 (4) | Ga1—Mg1—Y1xix | 128.28 (9) |
Mg1ix—Ga1—Y1ix | 66.80 (4) | Ga1i—Mg1—Y1xix | 57.70 (2) |
Mg1vii—Ga1—Y1ix | 134.247 (10) | Ga2—Mg1—Y1xix | 117.00 (8) |
Y1x—Ga1—Y1ix | 139.045 (6) | Ga2x—Mg1—Y1xix | 57.70 (3) |
Mg1—Ga1—Y1xi | 72.31 (4) | Mg1xvi—Mg1—Y1xix | 109.25 (6) |
Mg1ix—Ga1—Y1xi | 66.80 (4) | Mg1xiv—Mg1—Y1xix | 63.83 (6) |
Mg1vii—Ga1—Y1xi | 134.247 (10) | Y1x—Mg1—Y1xix | 67.47 (3) |
Y1x—Ga1—Y1xi | 74.593 (12) | Y1—Mg1—Y1xix | 118.53 (8) |
Y1ix—Ga1—Y1xi | 91.197 (16) | Y1ix—Mg1—Y1xix | 172.63 (13) |
Mg1—Ga1—Y1 | 66.80 (4) | Ga1—Mg1—Y1xi | 57.70 (2) |
Mg1ix—Ga1—Y1 | 134.247 (10) | Ga1i—Mg1—Y1xi | 128.28 (9) |
Mg1vii—Ga1—Y1 | 72.31 (4) | Ga2—Mg1—Y1xi | 117.00 (8) |
Y1x—Ga1—Y1 | 91.197 (16) | Ga2x—Mg1—Y1xi | 57.70 (3) |
Y1ix—Ga1—Y1 | 74.593 (12) | Mg1xvi—Mg1—Y1xi | 63.83 (6) |
Y1xi—Ga1—Y1 | 139.045 (6) | Mg1xiv—Mg1—Y1xi | 109.25 (6) |
Mg1—Ga1—Y1vii | 134.247 (10) | Y1x—Mg1—Y1xi | 67.47 (3) |
Mg1ix—Ga1—Y1vii | 72.31 (4) | Y1—Mg1—Y1xi | 118.53 (8) |
Mg1vii—Ga1—Y1vii | 66.80 (4) | Y1ix—Mg1—Y1xi | 78.67 (2) |
Y1x—Ga1—Y1vii | 139.045 (6) | Y1xix—Mg1—Y1xi | 100.84 (3) |
Y1ix—Ga1—Y1vii | 74.593 (12) | Ga1—Mg1—Y1xvii | 128.28 (9) |
Y1xi—Ga1—Y1vii | 139.045 (6) | Ga1i—Mg1—Y1xvii | 57.70 (2) |
Y1—Ga1—Y1vii | 74.593 (12) | Ga2—Mg1—Y1xvii | 57.70 (3) |
Mg1—Ga1—Y1xii | 134.247 (10) | Ga2x—Mg1—Y1xvii | 117.00 (8) |
Mg1ix—Ga1—Y1xii | 72.31 (4) | Mg1xvi—Mg1—Y1xvii | 109.25 (6) |
Mg1vii—Ga1—Y1xii | 66.80 (4) | Mg1xiv—Mg1—Y1xvii | 63.83 (6) |
Y1x—Ga1—Y1xii | 74.593 (12) | Y1x—Mg1—Y1xvii | 118.53 (8) |
Y1ix—Ga1—Y1xii | 139.045 (6) | Y1—Mg1—Y1xvii | 67.47 (3) |
Y1xi—Ga1—Y1xii | 74.593 (12) | Y1ix—Mg1—Y1xvii | 100.84 (3) |
Y1—Ga1—Y1xii | 139.045 (6) | Y1xix—Mg1—Y1xvii | 78.67 (2) |
Y1vii—Ga1—Y1xii | 91.197 (16) | Y1xi—Mg1—Y1xvii | 172.63 (13) |
Symmetry codes: (i) y, x+1, −z+2; (ii) x, y, z−1; (iii) y, x+1, −z+1; (iv) x+1, y, z; (v) −y+2, x−y+2, z; (vi) −x+y, −x+1, z−1; (vii) −x+y, −x+1, z; (viii) −y+2, x−y+2, z−1; (ix) −y+1, x−y+1, z; (x) x, y, z+1; (xi) −y+1, x−y+1, z+1; (xii) −x+y, −x+1, z+1; (xiii) −x+y−1, −x+1, z−1; (xiv) −y+1, x−y+2, z; (xv) −y+1, x−y+2, z−1; (xvi) −x+y−1, −x+1, z; (xvii) −x+y, −x+2, z; (xviii) x−1, y, z; (xix) −x+y, −x+2, z+1. |
Experimental details
Crystal data | |
Chemical formula | YMgGa |
Mr | 182.94 |
Crystal system, space group | Hexagonal, P62m |
Temperature (K) | 293 |
a, c (Å) | 7.2689 (10), 4.4205 (9) |
V (Å3) | 202.27 (6) |
Z | 3 |
Radiation type | Ag Kα, λ = 0.56085 Å |
µ (mm−1) | 16.83 |
Crystal size (mm) | 0.09 × 0.07 × 0.05 |
Data collection | |
Diffractometer | Bruker Apex1 diffractometer |
Absorption correction | Multi-scan (SADABS; Sheldrick, 2001) |
Tmin, Tmax | 0.276, 0.431 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 4365, 333, 324 |
Rint | 0.087 |
(sin θ/λ)max (Å−1) | 0.789 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.035, 0.088, 1.15 |
No. of reflections | 333 |
No. of parameters | 13 |
Δρmax, Δρmin (e Å−3) | 1.65, −1.78 |
Absolute structure | Flack (1983), 136 Friedel pairs |
Absolute structure parameter | 0.43 (5) |
Computer programs: SMART (Bruker, 2001), SAINT (Bruker, 2001), SAINT, SHELXTL (Sheldrick, 2001), DIAMOND (Crystal Impact, 2006), SHELXTL and publCIF (Westrip, 2007).
Ga1—Mg1 | 2.803 (3) | Ga2—Y1ii | 3.1033 (12) |
Ga1—Y1i | 3.0936 (4) | Mg1—Mg1iii | 3.076 (7) |
Ga2—Mg1 | 2.835 (3) | Mg1—Y1i | 3.255 (3) |
Symmetry codes: (i) x, y, z+1; (ii) −x+y, −x+2, z; (iii) −x+y−1, −x+1, z. |
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The potential use of magnesium alloys as storage materials for hydrogen has led to a large number of investigations on different magnesium alloys (Sakintuna et al., 2007). The studies of compounds in the systems Mg—Y, Mg—Ga and Mg—Y—Zn have shown some very interesting hydrogen absorbing properties, such as hydrogen induced nanowhisker formation and improved hydrogen absorption/desorption properties, as compared to pure Mg (Zlotea et al., 2006; Sahlberg & Andersson, 2007). Recently we have grown single crystals of YMgGa, and determined its crystal structure. The existence of this phase and the unit-cell parameters were previously reported (Kraft et al., 2003), but no crystal structure refinement has been published.
In the title compound Mg and Ga atoms form a network with distorted channels which are occupied by Y atoms. YMgGa crystallizes in the hexagonal ZrNiAl type structure which is related to the Fe2P type structure (Rundqvist & Jellinek, 1959). The two Fe sites are then occupied with Mg and Y atoms, and the two distinct Ga atoms are located at the corresponding P positions. The Mg—Ga distances, 2.803 (3) and 2.835 (3) Å, respectively, are in agreement with the binary Mg—Ga compounds (Smith et al., 1969). However, the Mg—Mg distance is 3.076 (7) Å, which is significantly shorter than in metallic magnesium, 3.20 Å (Owen et al., 1935). The strong Mg—Ga and Mg—Mg interactions lead to a three-dimensional network which is shown in Figure 1. The Y—Mg (3.255 (3) Å) and Y—Ga (3.0936 (4) Å and 3.1033 (12) Å) distances are likewise in agreement with the binary compounds (Smith et al., 1965; Schob & Parthé, 1965).
The coordination around Ga can be described as a slightly distorted capped trigonal prism. Ga1 is surrounded by 3 Mg atoms at 2.803 (3) Å and by 6 Y atoms at 3.0936 (4) Å in a [3 + 6] coordination. The Mg atoms form a triangle and the Y atoms are situated in the corners of a trigonal prism. Ga2 has a [6 + 3] coordination by 6 Mg at 2.835 (3) Å forming a trigonal prism that is capped by 3 Y at 3.1033 (12) Å. The Mg atom is tetrahedrally coordinated by 4 Ga atoms at 2.803 (3) and 2.835 (3) Å, and has 2 additional Mg neighbours at 3.076 (7) Å. The Y atom has 5 Ga neighbours in a pyramidal coordination and 6 additional Mg atoms forming a trigonal prism. The different coordination polyhedra around each atom are displayed in Figure 2.