Lanthanum dimagnesium

Belgacem, B.; Yahyaoui, S.; Demchenko, P.Y.; Bodak, O.I.; Dusek, M.; Ben Hassen, R.

doi:10.1107/S1600536805021343

Lanthanum dimagnesium

B. Belgacem, S. Yahyaoui, P. Y. Demchenko, O. I. Bodak, M. Dusek and R. Ben Hassen

Single crystals of the LaMg₂ cubic Laves phase were synthesized by arc melting. The binary LaMg₂ compound has been shown to adopt the MgCu₂-type structure. The coordination sphere of the rare earth metal, adopting a site symmetry of $\overline{1}$ , consists only of 12 Mg atoms. The site symmetry of the alkaline earth metal is $\overline{3}m$ , giving rise to superimposed distorted MgLa₆ and MgMg₆ octahedra.

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Supporting information

	Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536805021343/br6195sup1.cif Contains datablocks global, I
	Structure factor file (CIF format) https://doi.org/10.1107/S1600536805021343/br6195Isup2.hkl Contains datablock I

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Key indicators

Single-crystal X-ray study
T = 295 K
Mean () = 0.000 Å
R factor = 0.008
wR factor = 0.024
Data-to-parameter ratio = 12.5

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT041_ALERT_1_C Calc. and Rep. SumFormula Strings    Differ ....          ?
PLAT045_ALERT_1_C Calculated and Reported Z Differ by ............       4.00 Ratio

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           26.60
           From the CIF: _reflns_number_total                 50
           Count of symmetry unique reflns            1
           Completeness (_total/calc)           5000.00%
           TEST3: Check Friedels for noncentro structure
           Estimate of Friedel pairs measured        49
           Fraction of Friedel pairs measured    49.000
           Are heavy atom types Z>Si present        yes

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

   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
   0 ALERT type 3 Indicator that the structure quality may be low
   1 ALERT type 4 Improvement, methodology, query or suggestion

Computing details top

Data collection: KM4B8 (Galdecki et al., 1996); cell refinement: KM4B8; data reduction: JANA2000 (Petricek et al., 2000); program(s) used to solve structure: JANA2000; program(s) used to refine structure: JANA2000; molecular graphics: DIAMOND (Brandenburg, 1999); software used to prepare material for publication: JANA2000.

Lanthanum Dimagnesium top

Crystal data top

LaMg₂	D_x = 3.642 Mg m⁻³
M_r = 187.53	Mo Kα radiation, λ = 0.71069 Å
Cubic, Fd3m	Cell parameters from 25 reflections
Hall symbol: -F 4vw 2vw 3	θ = 2.2–27°
a = 8.810 (2) Å	µ = 12.55 mm⁻¹
V = 683.8 (3) Å³	T = 295 K
Z = 8	Elongated tablet, colorless
F(000) = 648	0.36 × 0.1 × 0.07 mm

Data collection top

Oxford Diffraction point-detector diffractometer	46 reflections with I > 3σ(I)
Radiation source: fine-focus sealed tube	R_int = 0.031
Graphite monochromator	θ_max = 26.6°, θ_min = 4.0°
ω/2θ scans	h = −11→11
Absorption correction: gaussian (JANA2000; Petricek et al., 2000)	k = −11→11
T_min = 0.323, T_max = 0.550	l = 0→11
648 measured reflections	3 standard reflections every 100 reflections
50 independent reflections	intensity decay: 1.1%

Refinement top

Refinement on F²	Primary atom site location: Patterson
R[F > 3σ(F)] = 0.008	Secondary atom site location: difference Fourier map
wR(F) = 0.025	Weighting scheme based on measured s.u.'s w = 1/(σ²(I) + 0.0004I²)
S = 1.14	(Δ/σ)_max = 0.002
50 reflections	Δρ_max = 0.11 e Å⁻³
4 parameters	Δρ_min = −0.09 e Å⁻³

Special details top

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 (Å²) top

	x	y	z	U_iso*/U_eq
La1	0.625	0.625	0.125	0.0195 (2)
Mg1	0	0.5	0	0.0145 (2)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
La1	0.0195 (2)	0.0195 (2)	0.0195 (2)	0	0	0
Mg1	0.0145 (3)	0.0145 (3)	0.0145 (3)	−0.0012 (5)	−0.0012 (5)	−0.0012 (5)

Geometric parameters (Å, º) top

La1—Mg1ⁱ	3.6524 (8)	La1—Mg1^x	3.6524 (8)
La1—Mg1ⁱⁱ	3.6524 (8)	La1—Mg1^xi	3.6524 (8)
La1—Mg1ⁱⁱⁱ	3.6524 (8)	La1—Mg1^xii	3.6524 (8)
La1—Mg1^iv	3.6524 (8)	Mg1—Mg1^xiii	3.1148 (7)
La1—Mg1^v	3.6524 (8)	Mg1—Mg1^xiv	3.1148 (7)
La1—Mg1^vi	3.6524 (8)	Mg1—Mg1^vii	3.1148 (7)
La1—Mg1^vii	3.6524 (8)	Mg1—Mg1^xv	3.1148 (7)
La1—Mg1^viii	3.6524 (8)	Mg1—Mg1^xvi	3.1148 (7)
La1—Mg1^ix	3.6524 (8)	Mg1—Mg1^xii	3.1148 (7)

Mg1ⁱ—La1—Mg1ⁱⁱ	117.036	Mg1^xi—La1—Mg1^v	50.479
Mg1ⁱ—La1—Mg1ⁱⁱⁱ	117.036	Mg1^xi—La1—Mg1^vi	95.216
Mg1ⁱ—La1—Mg1^iv	95.216	Mg1^xi—La1—Mg1^vii	95.216
Mg1ⁱ—La1—Mg1^v	95.216	Mg1^xi—La1—Mg1^viii	144.903
Mg1ⁱ—La1—Mg1^vi	50.479	Mg1^xi—La1—Mg1^ix	50.479
Mg1ⁱ—La1—Mg1^vii	144.903	Mg1^xi—La1—Mg1^x	117.036
Mg1ⁱ—La1—Mg1^viii	95.216	Mg1^xi—La1—Mg1^xii	117.036
Mg1ⁱ—La1—Mg1^ix	50.479	Mg1^xii—La1—Mg1ⁱ	144.903
Mg1ⁱ—La1—Mg1^x	95.216	Mg1^xii—La1—Mg1ⁱⁱ	50.479
Mg1ⁱ—La1—Mg1^xi	50.479	Mg1^xii—La1—Mg1ⁱⁱⁱ	95.216
Mg1ⁱ—La1—Mg1^xii	144.903	Mg1^xii—La1—Mg1^iv	50.479
Mg1ⁱⁱ—La1—Mg1ⁱ	117.036	Mg1^xii—La1—Mg1^v	95.216
Mg1ⁱⁱ—La1—Mg1ⁱⁱⁱ	117.036	Mg1^xii—La1—Mg1^vi	144.903
Mg1ⁱⁱ—La1—Mg1^iv	50.479	Mg1^xii—La1—Mg1^vii	50.479
Mg1ⁱⁱ—La1—Mg1^v	144.903	Mg1^xii—La1—Mg1^viii	95.216
Mg1ⁱⁱ—La1—Mg1^vi	95.216	Mg1^xii—La1—Mg1^ix	95.216
Mg1ⁱⁱ—La1—Mg1^vii	95.216	Mg1^xii—La1—Mg1^x	117.036
Mg1ⁱⁱ—La1—Mg1^viii	50.479	Mg1^xii—La1—Mg1^xi	117.036
Mg1ⁱⁱ—La1—Mg1^ix	95.216	La1^xvii—Mg1—La1^xviii	117.036
Mg1ⁱⁱ—La1—Mg1^x	95.216	La1^xvii—Mg1—La1^xix	117.036
Mg1ⁱⁱ—La1—Mg1^xi	144.903	La1^xvii—Mg1—La1^xx	180
Mg1ⁱⁱ—La1—Mg1^xii	50.479	La1^xvii—Mg1—La1^xxi	62.964
Mg1ⁱⁱⁱ—La1—Mg1ⁱ	117.036	La1^xvii—Mg1—La1^xxii	62.964
Mg1ⁱⁱⁱ—La1—Mg1ⁱⁱ	117.036	La1^xvii—Mg1—Mg1^xiii	115.239
Mg1ⁱⁱⁱ—La1—Mg1^iv	144.903	La1^xvii—Mg1—Mg1^xiv	64.761
Mg1ⁱⁱⁱ—La1—Mg1^v	50.479	La1^xvii—Mg1—Mg1^vii	115.239
Mg1ⁱⁱⁱ—La1—Mg1^vi	95.216	La1^xvii—Mg1—Mg1^xv	64.761
Mg1ⁱⁱⁱ—La1—Mg1^vii	50.479	La1^xvii—Mg1—Mg1^xvi	64.761
Mg1ⁱⁱⁱ—La1—Mg1^viii	95.216	La1^xvii—Mg1—Mg1^xii	115.239
Mg1ⁱⁱⁱ—La1—Mg1^ix	144.903	La1^xviii—Mg1—La1^xvii	117.036
Mg1ⁱⁱⁱ—La1—Mg1^x	50.479	La1^xviii—Mg1—La1^xix	117.036
Mg1ⁱⁱⁱ—La1—Mg1^xi	95.216	La1^xviii—Mg1—La1^xx	62.964
Mg1ⁱⁱⁱ—La1—Mg1^xii	95.216	La1^xviii—Mg1—La1^xxi	180
Mg1^iv—La1—Mg1ⁱ	95.216	La1^xviii—Mg1—La1^xxii	62.964
Mg1^iv—La1—Mg1ⁱⁱ	50.479	La1^xviii—Mg1—Mg1^xiii	64.761
Mg1^iv—La1—Mg1ⁱⁱⁱ	144.903	La1^xviii—Mg1—Mg1^xiv	115.239
Mg1^iv—La1—Mg1^v	117.036	La1^xviii—Mg1—Mg1^vii	64.761
Mg1^iv—La1—Mg1^vi	117.036	La1^xviii—Mg1—Mg1^xv	115.239
Mg1^iv—La1—Mg1^vii	95.216	La1^xviii—Mg1—Mg1^xvi	64.761
Mg1^iv—La1—Mg1^viii	95.216	La1^xviii—Mg1—Mg1^xii	115.239
Mg1^iv—La1—Mg1^ix	50.479	La1^xix—Mg1—La1^xvii	117.036
Mg1^iv—La1—Mg1^x	144.903	La1^xix—Mg1—La1^xviii	117.036
Mg1^iv—La1—Mg1^xi	95.216	La1^xix—Mg1—La1^xx	62.964
Mg1^iv—La1—Mg1^xii	50.479	La1^xix—Mg1—La1^xxi	62.964
Mg1^v—La1—Mg1ⁱ	95.216	La1^xix—Mg1—La1^xxii	180
Mg1^v—La1—Mg1ⁱⁱ	144.903	La1^xix—Mg1—Mg1^xiii	64.761
Mg1^v—La1—Mg1ⁱⁱⁱ	50.479	La1^xix—Mg1—Mg1^xiv	115.239
Mg1^v—La1—Mg1^iv	117.036	La1^xix—Mg1—Mg1^vii	115.239
Mg1^v—La1—Mg1^vi	117.036	La1^xix—Mg1—Mg1^xv	64.761
Mg1^v—La1—Mg1^vii	50.479	La1^xix—Mg1—Mg1^xvi	115.239
Mg1^v—La1—Mg1^viii	144.903	La1^xix—Mg1—Mg1^xii	64.761
Mg1^v—La1—Mg1^ix	95.216	La1^xx—Mg1—La1^xvii	180
Mg1^v—La1—Mg1^x	95.216	La1^xx—Mg1—La1^xviii	62.964
Mg1^v—La1—Mg1^xi	50.479	La1^xx—Mg1—La1^xix	62.964
Mg1^v—La1—Mg1^xii	95.216	La1^xx—Mg1—La1^xxi	117.036
Mg1^vi—La1—Mg1ⁱ	50.479	La1^xx—Mg1—La1^xxii	117.036
Mg1^vi—La1—Mg1ⁱⁱ	95.216	La1^xx—Mg1—Mg1^xiii	64.761
Mg1^vi—La1—Mg1ⁱⁱⁱ	95.216	La1^xx—Mg1—Mg1^xiv	115.239
Mg1^vi—La1—Mg1^iv	117.036	La1^xx—Mg1—Mg1^vii	64.761
Mg1^vi—La1—Mg1^v	117.036	La1^xx—Mg1—Mg1^xv	115.239
Mg1^vi—La1—Mg1^vii	144.903	La1^xx—Mg1—Mg1^xvi	115.239
Mg1^vi—La1—Mg1^viii	50.479	La1^xx—Mg1—Mg1^xii	64.761
Mg1^vi—La1—Mg1^ix	95.216	La1^xxi—Mg1—La1^xvii	62.964
Mg1^vi—La1—Mg1^x	50.479	La1^xxi—Mg1—La1^xviii	180
Mg1^vi—La1—Mg1^xi	95.216	La1^xxi—Mg1—La1^xix	62.964
Mg1^vi—La1—Mg1^xii	144.903	La1^xxi—Mg1—La1^xx	117.036
Mg1^vii—La1—Mg1ⁱ	144.903	La1^xxi—Mg1—La1^xxii	117.036
Mg1^vii—La1—Mg1ⁱⁱ	95.216	La1^xxi—Mg1—Mg1^xiii	115.239
Mg1^vii—La1—Mg1ⁱⁱⁱ	50.479	La1^xxi—Mg1—Mg1^xiv	64.761
Mg1^vii—La1—Mg1^iv	95.216	La1^xxi—Mg1—Mg1^vii	115.239
Mg1^vii—La1—Mg1^v	50.479	La1^xxi—Mg1—Mg1^xv	64.761
Mg1^vii—La1—Mg1^vi	144.903	La1^xxi—Mg1—Mg1^xvi	115.239
Mg1^vii—La1—Mg1^viii	117.036	La1^xxi—Mg1—Mg1^xii	64.761
Mg1^vii—La1—Mg1^ix	117.036	La1^xxii—Mg1—La1^xvii	62.964
Mg1^vii—La1—Mg1^x	95.216	La1^xxii—Mg1—La1^xviii	62.964
Mg1^vii—La1—Mg1^xi	95.216	La1^xxii—Mg1—La1^xix	180
Mg1^vii—La1—Mg1^xii	50.479	La1^xxii—Mg1—La1^xx	117.036
Mg1^viii—La1—Mg1ⁱ	95.216	La1^xxii—Mg1—La1^xxi	117.036
Mg1^viii—La1—Mg1ⁱⁱ	50.479	La1^xxii—Mg1—Mg1^xiii	115.239
Mg1^viii—La1—Mg1ⁱⁱⁱ	95.216	La1^xxii—Mg1—Mg1^xiv	64.761
Mg1^viii—La1—Mg1^iv	95.216	La1^xxii—Mg1—Mg1^vii	64.761
Mg1^viii—La1—Mg1^v	144.903	La1^xxii—Mg1—Mg1^xv	115.239
Mg1^viii—La1—Mg1^vi	50.479	La1^xxii—Mg1—Mg1^xvi	64.761
Mg1^viii—La1—Mg1^vii	117.036	La1^xxii—Mg1—Mg1^xii	115.239
Mg1^viii—La1—Mg1^ix	117.036	Mg1^xiii—Mg1—Mg1^xiv	180
Mg1^viii—La1—Mg1^x	50.479	Mg1^xiii—Mg1—Mg1^vii	120
Mg1^viii—La1—Mg1^xi	144.903	Mg1^xiii—Mg1—Mg1^xv	60
Mg1^viii—La1—Mg1^xii	95.216	Mg1^xiii—Mg1—Mg1^xvi	60
Mg1^ix—La1—Mg1ⁱ	50.479	Mg1^xiii—Mg1—Mg1^xii	120
Mg1^ix—La1—Mg1ⁱⁱ	95.216	Mg1^xiv—Mg1—Mg1^xiii	180
Mg1^ix—La1—Mg1ⁱⁱⁱ	144.903	Mg1^xiv—Mg1—Mg1^vii	60
Mg1^ix—La1—Mg1^iv	50.479	Mg1^xiv—Mg1—Mg1^xv	120
Mg1^ix—La1—Mg1^v	95.216	Mg1^xiv—Mg1—Mg1^xvi	120
Mg1^ix—La1—Mg1^vi	95.216	Mg1^xiv—Mg1—Mg1^xii	60
Mg1^ix—La1—Mg1^vii	117.036	Mg1^vii—Mg1—Mg1^xiii	120
Mg1^ix—La1—Mg1^viii	117.036	Mg1^vii—Mg1—Mg1^xiv	60
Mg1^ix—La1—Mg1^x	144.903	Mg1^vii—Mg1—Mg1^xv	180
Mg1^ix—La1—Mg1^xi	50.479	Mg1^vii—Mg1—Mg1^xvi	120
Mg1^ix—La1—Mg1^xii	95.216	Mg1^vii—Mg1—Mg1^xii	60
Mg1^x—La1—Mg1ⁱ	95.216	Mg1^xv—Mg1—Mg1^xiii	60
Mg1^x—La1—Mg1ⁱⁱ	95.216	Mg1^xv—Mg1—Mg1^xiv	120
Mg1^x—La1—Mg1ⁱⁱⁱ	50.479	Mg1^xv—Mg1—Mg1^vii	180
Mg1^x—La1—Mg1^iv	144.903	Mg1^xv—Mg1—Mg1^xvi	60
Mg1^x—La1—Mg1^v	95.216	Mg1^xv—Mg1—Mg1^xii	120
Mg1^x—La1—Mg1^vi	50.479	Mg1^xvi—Mg1—Mg1^xiii	60
Mg1^x—La1—Mg1^vii	95.216	Mg1^xvi—Mg1—Mg1^xiv	120
Mg1^x—La1—Mg1^viii	50.479	Mg1^xvi—Mg1—Mg1^vii	120
Mg1^x—La1—Mg1^ix	144.903	Mg1^xvi—Mg1—Mg1^xv	60
Mg1^x—La1—Mg1^xi	117.036	Mg1^xvi—Mg1—Mg1^xii	180
Mg1^x—La1—Mg1^xii	117.036	Mg1^xii—Mg1—Mg1^xiii	120
Mg1^xi—La1—Mg1ⁱ	50.479	Mg1^xii—Mg1—Mg1^xiv	60
Mg1^xi—La1—Mg1ⁱⁱ	144.903	Mg1^xii—Mg1—Mg1^vii	60
Mg1^xi—La1—Mg1ⁱⁱⁱ	95.216	Mg1^xii—Mg1—Mg1^xv	120
Mg1^xi—La1—Mg1^iv	95.216	Mg1^xii—Mg1—Mg1^xvi	180

Symmetry codes: (i) x+1, y, z; (ii) x+1/2, y, z+1/2; (iii) x+1/2, y+1/2, z; (iv) −y+1, x+1/4, z+1/4; (v) −y+1, x+3/4, z−1/4; (vi) −y+3/2, x+3/4, z+1/4; (vii) −x+1/4, −y+5/4, z; (viii) −x+3/4, −y+5/4, z+1/2; (ix) −x+3/4, −y+3/4, z; (x) y+1/4, −x+1, z+1/4; (xi) y+1/4, −x+1/2, z−1/4; (xii) y−1/4, −x+1/2, z+1/4; (xiii) −y+1/2, x+1/4, z−1/4; (xiv) −y+1/2, x+3/4, z+1/4; (xv) −x−1/4, −y+3/4, z; (xvi) y−3/4, −x+1/2, z−1/4; (xvii) x−1, y, z; (xviii) x−1/2, y, z−1/2; (xix) x−1/2, y−1/2, z; (xx) −x+1, −y+1, −z; (xxi) −x+1/2, −y+1, −z+1/2; (xxii) −x+1/2, −y+3/2, −z.

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