Strontium tetra­gallide

Single crystals of the title compound, SrGa₄, were synthesized from the corresponding elements using molten Sn metal as a solvent. The structure determination suggested the product to be a binary phase with composition SrGa₄, which crystallizes with the BaAl₄ type in the body-centered tetra­gonal space group I4/mmm (No. 139). The three atoms in the asymmetric unit lie on special positions with Wyckoff symbols 2a (Sr), 4d and 4e for the Ga atoms.

Key indicators

• Single-crystal X-ray study
• T = 120 K
• Mean [sigma]() = 0.000 Å
• R factor = 0.017
• wR factor = 0.042
• Data-to-parameter ratio = 11.1

checkCIF/PLATON results

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Alert level C
PLAT041_ALERT_1_C Calc. and Rep. SumFormula Strings    Differ ....          ?
PLAT042_ALERT_1_C Calc. and Rep. MoietyFormula Strings Differ ....          ?
PLAT045_ALERT_1_C Calculated and Reported Z Differ by ............      16.00 Ratio
PLAT731_ALERT_1_C Bond    Calc  3.3862(13), Rep   3.3861(6) ......       2.17 su-Rat
              SR   -GA2     1.555  25.445
PLAT731_ALERT_1_C Bond    Calc  3.3862(13), Rep   3.3861(6) ......       2.17 su-Rat
              SR   -GA2     1.555   9.554

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

   5 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
   0 ALERT type 4 Improvement, methodology, query or suggestion

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Computing details

Data collection: SMART (Bruker, 2002); cell refinement: SMART; data reduction: SAINT (Bruker, 2002); program(s) used to solve structure: SHELXTL (Sheldrick, 2001); program(s) used to refine structure: SHELXTL (Sheldrick, 2001); molecular graphics: XP in SHELXTL; software used to prepare material for publication: SHELXTL.

Strontium tetragallide

Crystal data

SrGa4	Dx = 5.735 Mg m^−3
Mr = 366.50	Mo Kα radiation, λ = 0.71073 Å
Tetragonal, I4/mmm	Cell parameters from 768 reflections
Hall symbol: -I 4 2	θ = 3.8–28.1°
a = 4.4474 (8) Å	µ = 37.32 mm^−1
c = 10.730 (4) Å	T = 120 K
V = 212.23 (10) Å^3	Irregular, silver
Z = 2	0.05 × 0.03 × 0.02 mm
F(000) = 324

Data collection

Bruker APEX SMART diffractometer	100 independent reflections
Radiation source: fine-focus sealed tube	94 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.024
Detector resolution: 8.3 pixels mm^-1	θmax = 28.1°, θmin = 3.8°
ω scans	h = −5→5
Absorption correction: multi-scan (SADABS; Sheldrick, 2003)	k = −5→5
Tmin = 0.234, Tmax = 0.475	l = −13→9
768 measured reflections

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)] = 0.017	w = 1/[σ^2(Fo^2) + (0.0297P)^2] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.042	(Δ/σ)max < 0.001
S = 1.03	Δρmax = 0.91 e Å^−3
100 reflections	Δρmin = −1.16 e Å^−3
9 parameters	Extinction correction: SHELXTL, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
0 restraints	Extinction coefficient: 0.0043 (10)

Special details

Experimental. Data collection is performed with four batch runs at φ = 0.00 ° (450 frames), at φ = 90.00 ° (450 frames), at φ = 180.00 ° (450 frames), and at φ = 270.00 (450 frames). Frame width = 0.40 \& in ω. Data is merged, corrected for decay, and treated with multi-scan absorption corrections.

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
Sr	0.0000	0.0000	0.0000	0.0074 (3)
Ga1	0.0000	0.5000	0.2500	0.0076 (3)
Ga2	0.0000	0.0000	0.38299 (9)	0.0072 (3)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Sr	0.0076 (4)	0.0076 (4)	0.0072 (6)	0.000	0.000	0.000
Ga1	0.0079 (3)	0.0079 (3)	0.0071 (6)	0.000	0.000	0.000
Ga2	0.0078 (4)	0.0078 (4)	0.0058 (5)	0.000	0.000	0.000

Geometric parameters (Å, º)

Sr—Ga2^i	3.3861 (7)	Ga1—Ga2^x	2.6422 (7)
Sr—Ga2^ii	3.3861 (7)	Ga1—Ga2^i	2.6422 (7)
Sr—Ga2^iii	3.3861 (6)	Ga1—Sr^xi	3.4843 (8)
Sr—Ga2^iv	3.3861 (6)	Ga1—Sr^xii	3.4843 (8)
Sr—Ga2^v	3.3861 (7)	Ga1—Sr^x	3.4843 (8)
Sr—Ga2^vi	3.3861 (7)	Ga2—Ga2^xiii	2.511 (2)
Sr—Ga2^vii	3.3861 (7)	Ga2—Ga1^v	2.6422 (7)
Sr—Ga2^viii	3.3861 (7)	Ga2—Ga1^xiv	2.6422 (7)
Sr—Ga1	3.4843 (8)	Ga2—Ga1^i	2.6422 (7)
Sr—Ga1^ix	3.4843 (8)	Ga2—Sr^xi	3.3861 (7)
Sr—Ga1^ii	3.4843 (8)	Ga2—Sr^xv	3.3861 (7)
Sr—Ga1^i	3.4843 (8)	Ga2—Sr^xii	3.3861 (7)
Ga1—Ga2	2.6422 (7)	Ga2—Sr^xvi	3.3861 (7)
Ga1—Ga2^v	2.6422 (7)
Ga2^i—Sr—Ga2^ii	180.00 (3)	Ga1^ii—Sr—Ga1^i	180.0
Ga2^i—Sr—Ga2^iii	136.47 (3)	Ga2—Ga1—Ga2^v	106.959 (19)
Ga2^ii—Sr—Ga2^iii	43.53 (3)	Ga2—Ga1—Ga2^x	114.62 (4)
Ga2^i—Sr—Ga2^iv	43.53 (3)	Ga2^v—Ga1—Ga2^x	106.960 (19)
Ga2^ii—Sr—Ga2^iv	136.47 (3)	Ga2—Ga1—Ga2^i	106.959 (19)
Ga2^iii—Sr—Ga2^iv	180.00 (3)	Ga2^v—Ga1—Ga2^i	114.62 (4)
Ga2^i—Sr—Ga2^v	82.099 (12)	Ga2^x—Ga1—Ga2^i	106.960 (19)
Ga2^ii—Sr—Ga2^v	97.901 (12)	Ga2—Ga1—Sr	83.03 (3)
Ga2^iii—Sr—Ga2^v	82.099 (12)	Ga2^v—Ga1—Sr	65.430 (17)
Ga2^iv—Sr—Ga2^v	97.901 (12)	Ga2^x—Ga1—Sr	162.348 (17)
Ga2^i—Sr—Ga2^vi	82.099 (12)	Ga2^i—Ga1—Sr	65.430 (17)
Ga2^ii—Sr—Ga2^vi	97.901 (12)	Ga2—Ga1—Sr^xi	65.431 (17)
Ga2^iii—Sr—Ga2^vi	82.099 (12)	Ga2^v—Ga1—Sr^xi	162.348 (17)
Ga2^iv—Sr—Ga2^vi	97.901 (12)	Ga2^x—Ga1—Sr^xi	65.430 (17)
Ga2^v—Sr—Ga2^vi	136.47 (3)	Ga2^i—Ga1—Sr^xi	83.03 (3)
Ga2^i—Sr—Ga2^vii	97.901 (12)	Sr—Ga1—Sr^xi	126.349 (14)
Ga2^ii—Sr—Ga2^vii	82.099 (12)	Ga2—Ga1—Sr^xii	65.431 (17)
Ga2^iii—Sr—Ga2^vii	97.901 (12)	Ga2^v—Ga1—Sr^xii	83.03 (3)
Ga2^iv—Sr—Ga2^vii	82.099 (12)	Ga2^x—Ga1—Sr^xii	65.430 (17)
Ga2^v—Sr—Ga2^vii	43.53 (3)	Ga2^i—Ga1—Sr^xii	162.348 (17)
Ga2^vi—Sr—Ga2^vii	180.0	Sr—Ga1—Sr^xii	126.349 (14)
Ga2^i—Sr—Ga2^viii	97.901 (12)	Sr^xi—Ga1—Sr^xii	79.32 (2)
Ga2^ii—Sr—Ga2^viii	82.099 (12)	Ga2—Ga1—Sr^x	162.347 (17)
Ga2^iii—Sr—Ga2^viii	97.901 (12)	Ga2^v—Ga1—Sr^x	65.430 (17)
Ga2^iv—Sr—Ga2^viii	82.099 (12)	Ga2^x—Ga1—Sr^x	83.03 (3)
Ga2^v—Sr—Ga2^viii	180.0	Ga2^i—Ga1—Sr^x	65.430 (17)
Ga2^vi—Sr—Ga2^viii	43.53 (3)	Sr—Ga1—Sr^x	79.32 (2)
Ga2^vii—Sr—Ga2^viii	136.47 (3)	Sr^xi—Ga1—Sr^x	126.349 (15)
Ga2^i—Sr—Ga1	45.207 (11)	Sr^xii—Ga1—Sr^x	126.349 (15)
Ga2^ii—Sr—Ga1	134.793 (11)	Ga2^xiii—Ga2—Ga1^v	122.69 (2)
Ga2^iii—Sr—Ga1	97.68 (2)	Ga2^xiii—Ga2—Ga1^xiv	122.69 (2)
Ga2^iv—Sr—Ga1	82.32 (2)	Ga1^v—Ga2—Ga1^xiv	73.041 (19)
Ga2^v—Sr—Ga1	45.207 (11)	Ga2^xiii—Ga2—Ga1	122.69 (2)
Ga2^vi—Sr—Ga1	97.68 (2)	Ga1^v—Ga2—Ga1	73.041 (19)
Ga2^vii—Sr—Ga1	82.32 (2)	Ga1^xiv—Ga2—Ga1	114.62 (4)
Ga2^viii—Sr—Ga1	134.793 (11)	Ga2^xiii—Ga2—Ga1^i	122.69 (2)
Ga2^i—Sr—Ga1^ix	134.793 (11)	Ga1^v—Ga2—Ga1^i	114.62 (4)
Ga2^ii—Sr—Ga1^ix	45.207 (11)	Ga1^xiv—Ga2—Ga1^i	73.041 (19)
Ga2^iii—Sr—Ga1^ix	82.32 (2)	Ga1—Ga2—Ga1^i	73.041 (19)
Ga2^iv—Sr—Ga1^ix	97.68 (2)	Ga2^xiii—Ga2—Sr^xi	68.237 (17)
Ga2^v—Sr—Ga1^ix	134.793 (11)	Ga1^v—Ga2—Sr^xi	138.846 (8)
Ga2^vi—Sr—Ga1^ix	82.32 (2)	Ga1^xiv—Ga2—Sr^xi	138.846 (8)
Ga2^vii—Sr—Ga1^ix	97.68 (2)	Ga1—Ga2—Sr^xi	69.363 (14)
Ga2^viii—Sr—Ga1^ix	45.207 (11)	Ga1^i—Ga2—Sr^xi	69.363 (14)
Ga1—Sr—Ga1^ix	180.0	Ga2^xiii—Ga2—Sr^xv	68.237 (16)
Ga2^i—Sr—Ga1^ii	134.793 (11)	Ga1^v—Ga2—Sr^xv	69.363 (14)
Ga2^ii—Sr—Ga1^ii	45.207 (11)	Ga1^xiv—Ga2—Sr^xv	69.363 (14)
Ga2^iii—Sr—Ga1^ii	82.32 (2)	Ga1—Ga2—Sr^xv	138.846 (8)
Ga2^iv—Sr—Ga1^ii	97.68 (2)	Ga1^i—Ga2—Sr^xv	138.846 (8)
Ga2^v—Sr—Ga1^ii	82.32 (2)	Sr^xi—Ga2—Sr^xv	136.47 (3)
Ga2^vi—Sr—Ga1^ii	134.793 (11)	Ga2^xiii—Ga2—Sr^xii	68.237 (17)
Ga2^vii—Sr—Ga1^ii	45.207 (11)	Ga1^v—Ga2—Sr^xii	69.363 (14)
Ga2^viii—Sr—Ga1^ii	97.68 (2)	Ga1^xiv—Ga2—Sr^xii	138.846 (8)
Ga1—Sr—Ga1^ii	126.349 (14)	Ga1—Ga2—Sr^xii	69.363 (14)
Ga1^ix—Sr—Ga1^ii	53.651 (14)	Ga1^i—Ga2—Sr^xii	138.846 (8)
Ga2^i—Sr—Ga1^i	45.207 (11)	Sr^xi—Ga2—Sr^xii	82.099 (11)
Ga2^ii—Sr—Ga1^i	134.793 (11)	Sr^xv—Ga2—Sr^xii	82.099 (12)
Ga2^iii—Sr—Ga1^i	97.68 (2)	Ga2^xiii—Ga2—Sr^xvi	68.237 (17)
Ga2^iv—Sr—Ga1^i	82.32 (2)	Ga1^v—Ga2—Sr^xvi	138.846 (8)
Ga2^v—Sr—Ga1^i	97.68 (2)	Ga1^xiv—Ga2—Sr^xvi	69.363 (14)
Ga2^vi—Sr—Ga1^i	45.207 (11)	Ga1—Ga2—Sr^xvi	138.846 (8)
Ga2^vii—Sr—Ga1^i	134.793 (11)	Ga1^i—Ga2—Sr^xvi	69.363 (14)
Ga2^viii—Sr—Ga1^i	82.32 (2)	Sr^xi—Ga2—Sr^xvi	82.099 (11)
Ga1—Sr—Ga1^i	53.651 (14)	Sr^xv—Ga2—Sr^xvi	82.099 (12)
Ga1^ix—Sr—Ga1^i	126.349 (14)	Sr^xii—Ga2—Sr^xvi	136.47 (3)

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