La₅Zn₂Sn

A single crystal of penta­lanthanum dizinc stannide, La₅Zn₂Sn, was obtained from the elements in a resistance furnace. It belongs to the Mo₅SiB₂ structure type, which is a ternary ordered variant of the Cr₅B₃ structure type. The space is filled by bicapped tetra­gonal anti­prisms from lanthanum atoms around tin atoms sharing their vertices. Zinc atoms fill voids between these bicapped tetra­gonal anti­prisms. All four atoms in the asymmetric unit reside on special positions with the following site symmetries: La1 (..m); La2 (4/m..); Zn (m.2m); Sn (422).

Related literature

For general background to {Tb,La}–Zn–{Sn,Pb} ternary systems, see: Manfrinetti & Pani, (2005); Oshchapovsky et al. (2010, 2011); Pavlyuk et al. (2009). For related structures, see: Bertaut (1953). For isotypic structures, see: Aronsson (1958).

Experimental

Crystal data

• La₅Zn₂Sn

• M_r = 944.04

• Tetragonal, I 4/m c m

• a = 8.3277 (12) Å

• c = 14.334 (3) Å

• V = 994.1 (3) ų

• Z = 4

• Mo Kα radiation

• μ = 28.10 mm⁻¹

• T = 293 K

• 0.04 × 0.04 × 0.01 mm

Data collection

• Bruker APEXII CCD diffractometer

• Absorption correction: multi-scan (SADABS; Bruker, 2004) T_min = 0.340, T_max = 0.765

• 9291 measured reflections

• 419 independent reflections

• 346 reflections with I > 2σ(I)

• R_int = 0.091

Refinement

• R[F² > 2σ(F²)] = 0.027

• wR(F²) = 0.056

• S = 1.14

• 419 reflections

• 14 parameters

• Δρ_max = 1.60 e Å⁻³

• Δρ_min = −1.59 e Å⁻³

Data collection: APEX2 (Bruker, 2004); cell refinement: SAINT (Bruker, 2004); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008) and JANA2006 (Petricek et al., 2006); molecular graphics: DIAMOND (Brandenburg, 2006) and VESTA (Momma & Izumi, 2008); software used to prepare material for publication: publCIF (Westrip, 2010).

Supporting information

S1. Comment

Ternary compounds formed by rare-earth, transition metal and d-metal often have interesting physical and chemical properties e. g. strong ferromagnetism, hydrogen storage capabilities and so on. The systematic investigation of the components interaction in the {Tb, La}-Zn-{Sn,Pb} ternary systems can lead to development of functional materials (for crystal structures of ternary compounds see: TbZnSn –Manfrinetti & Pani, (2005), Pavlyuk et al., (2009), TbZnSn₂ - Pavlyuk et al., (2009), Tb₁₃ZnSn₁₃ -Oshchapovsky et al., (2010) and LaZn_12.37 -Oshchapovsky et al., (2011)).

The title compound crystallizes in Mo₅SiB₂ (Aronsson, 1958) structure type which is an ordered superstructure of Cr₅B₃ type (Bertaut, 1953). Unit cell projection together with coordination polyhedra are given in Fig.1. Coordination polyhedra of the La1 atoms are 16- vertex polyhedra. Sn atoms are surrounded by ten neighbours forming bicapped tetragonal antiprism. La2 atoms are enclosed into trigon - tetrahexahedron with CN=14. And coordination polyhedra of the Zn atoms are bicapped trigonal prisms with CN=9. Coordination polyhedra of Sn atoms share their vertices forming three dimensional framework. The voids in this framework are filled by zinc atoms. (See graphical abstract).

The way of bond formation in this compound was assumed using only X-ray diffraction data. Further structure refinement was carried out by means of Jana2006 software package using anharmonic ADP for La1 and Zn atoms. Anharmonic displacement parameters for other atoms were not refined because in case of their refinement their standard deviations were larger than obtained values. As the result we gained lower absolute values of peak and hole in the difference Fourier map (1.02 and -1.17 e Å^-3 respectively). The resulting isosurface drawn at the level 0.308 e/ų and sections of difference Fourier map are given in Fig. 2. These maps and sections are noisy but some trends in location of positive and negative regions can be noticed. Positive residual electron density is mostly situated around zinc atoms and near layers made of tin atoms. Negative residual density is mostly located between lanthanum atoms which means that lanthanum atoms donate their electrons to zinc and tin atoms. Similar behaviour of lanthanum atoms can be observed in the LaZn_12.37 compound using electronic structure calculations (See Oshchapovsky et al., (2011)). As a conclusion this compound besides dominate metallic bonding has a weak ionic interaction between lanthanum and zinc and tin atoms.

Related literature

For general background to {Tb, La}–Zn–{Sn,Pb} ternary systems, see: Manfrinetti & Pani, (2005); Oshchapovsky et al. (2010, 2011); Pavlyuk et al. (2009). For related structures, see: Bertaut (1953). For isostructural/isotypic structures, see: Aronsson (1958).

S2. Experimental

Small good quality single-crystal of title compound was isolated from alloy with composition La₇ZnSn₂ during systematic investigation of lanthanum-rich region of La—Zn—Sn ternary system. The samples with high lanthanum contents were prepared by melting of pieces of pure metals in evacuated quartz ampoule with subsequent annealing at 600 ⁰C for 30 days. Further phase analysis showed the existence of title compound in sample with composition La₇ZnSn₂ as well as in the other lanthanum-rich ternary alloys. However they were non equilibrium.

Computing details

Data collection: APEX2 (Bruker, 2004); cell refinement: SAINT (Bruker, 2004); data reduction: SAINT (Bruker, 2004); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008), JANA2006 (Petricek et al., 2006) and SUPERFLIP (Palatinus & Chapuis, 2007); molecular graphics: DIAMOND (Brandenburg, 2006) and VESTA (Momma & Izumi, 2008); software used to prepare material for publication: publCIF (Westrip, 2010).

Figures

	Fig. 1. Unit cell projection and coordination polyhedra in the La5Zn2Sn compound
	Fig. 2. Isosurface drawn at 0.308 e/Å^3 and sections of difference Fourier map after the refinement of crystal structure of the La5Zn2Sn compound

Pentalanthanum dizinc stannide

Crystal data

La5Zn2Sn	Dx = 6.308 Mg m^−3
Mr = 944.04	Mo Kα radiation, λ = 0.71073 Å
Tetragonal, I4/mcm	Cell parameters from 1223 reflections
Hall symbol: -I 4 2c	θ = 5.7–26.1°
a = 8.3277 (12) Å	µ = 28.10 mm^−1
c = 14.334 (3) Å	T = 293 K
V = 994.1 (3) Å^3	Plate, grey
Z = 4	0.04 × 0.04 × 0.01 mm
F(000) = 1580.0

Data collection

Bruker APEXII CCD diffractometer	419 independent reflections
Radiation source: sealed tube	346 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.091
Detector resolution: 8.366 pixels mm^-1	θmax = 30.1°, θmin = 2.8°
ϕ and ω scans	h = −11→11
Absorption correction: multi-scan (SADABS; Bruker, 2004)	k = −11→11
Tmin = 0.340, Tmax = 0.765	l = −20→19
9291 measured reflections

Refinement

Refinement on F^2	0 restraints
Least-squares matrix: full	Primary atom site location: structure-invariant direct methods
R[F^2 > 2σ(F^2)] = 0.027	Secondary atom site location: difference Fourier map
wR(F^2) = 0.056	w = 1/[σ^2(Fo^2) + (0.0144P)^2 + 16.4322P] where P = (Fo^2 + 2Fc^2)/3
S = 1.14	(Δ/σ)max = 0.004
419 reflections	Δρmax = 1.60 e Å^−3
14 parameters	Δρmin = −1.59 e Å^−3

Special details

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
La1	0.66685 (5)	0.16685 (5)	0.14853 (4)	0.02054 (16)
La2	0.0000	0.0000	0.0000	0.0357 (3)
Zn	0.12383 (12)	0.62383 (12)	0.0000	0.0139 (3)
Sn	0.0000	0.0000	0.2500	0.0145 (2)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
La1	0.01937 (19)	0.01937 (19)	0.0229 (3)	0.00430 (19)	0.000	0.000
La2	0.0291 (4)	0.0291 (4)	0.0490 (8)	0.000	0.000	0.000
Zn	0.0123 (4)	0.0123 (4)	0.0171 (7)	0.0013 (5)	0.000	0.000
Sn	0.0129 (3)	0.0129 (3)	0.0177 (5)	0.000	0.000	0.000

Geometric parameters (Å, º)

La1—Zn^i	3.2436 (9)	La2—La1^xvii	3.7630 (6)
La1—Zn^ii	3.2436 (9)	Zn—Zn^x	2.917 (3)
La1—Zn^iii	3.2573 (12)	Zn—La1^xviii	3.2436 (9)
La1—Sn^iv	3.4268 (5)	Zn—La1^xvi	3.2436 (9)
La1—Sn^v	3.4268 (5)	Zn—La1^xix	3.2436 (9)
La1—La1^vi	3.5068 (12)	Zn—La1^xiv	3.2436 (9)
La1—La2^iv	3.7630 (6)	Zn—La1^xx	3.2573 (12)
La1—La2^vii	3.7630 (6)	Zn—La1^iii	3.2573 (12)
La1—La1^viii	3.9301 (12)	Zn—La2^xxi	3.2980 (8)
La2—Zn^ix	3.2980 (8)	Zn—La2^vii	3.2980 (8)
La2—Zn^ii	3.2980 (8)	Sn—La1^xxii	3.4268 (5)
La2—Zn^x	3.2980 (8)	Sn—La1^xvii	3.4268 (5)
La2—Zn^xi	3.2980 (8)	Sn—La1^xiv	3.4268 (5)
La2—Sn^xii	3.5835 (7)	Sn—La1^v	3.4268 (5)
La2—Sn	3.5835 (7)	Sn—La1^xxiii	3.4268 (5)
La2—La1^xiii	3.7630 (6)	Sn—La1^xxiv	3.4268 (5)
La2—La1^xiv	3.7630 (6)	Sn—La1^viii	3.4268 (5)
La2—La1^xv	3.7630 (6)	Sn—La1^xxv	3.4268 (5)
La2—La1^viii	3.7630 (6)	Sn—La2^xxvi	3.5835 (7)
La2—La1^xvi	3.7630 (6)
Zn^i—La1—Zn^ii	53.44 (5)	Zn^ii—La2—La1^xvi	54.461 (17)
Zn^i—La1—Zn^iii	91.69 (2)	Zn^x—La2—La1^xvi	54.208 (18)
Zn^ii—La1—Zn^iii	91.69 (2)	Zn^xi—La2—La1^xvi	125.792 (18)
Zn^i—La1—Sn^iv	93.75 (2)	Sn^xii—La2—La1^xvi	55.545 (10)
Zn^ii—La1—Sn^iv	146.93 (3)	Sn—La2—La1^xvi	124.455 (10)
Zn^iii—La1—Sn^iv	93.506 (15)	La1^xiii—La2—La1^xvi	111.09 (2)
Zn^i—La1—Sn^v	146.93 (3)	La1^xiv—La2—La1^xvi	68.91 (2)
Zn^ii—La1—Sn^v	93.75 (2)	La1^xv—La2—La1^xvi	71.332 (10)
Zn^iii—La1—Sn^v	93.506 (15)	La1^viii—La2—La1^xvi	108.668 (10)
Sn^iv—La1—Sn^v	118.450 (18)	Zn^ix—La2—La1^xvii	54.461 (17)
Zn^i—La1—La1^vi	151.98 (2)	Zn^ii—La2—La1^xvii	125.539 (17)
Zn^ii—La1—La1^vi	151.98 (2)	Zn^x—La2—La1^xvii	125.792 (18)
Zn^iii—La1—La1^vi	96.86 (3)	Zn^xi—La2—La1^xvii	54.208 (18)
Sn^iv—La1—La1^vi	59.225 (9)	Sn^xii—La2—La1^xvii	124.455 (10)
Sn^v—La1—La1^vi	59.225 (9)	Sn—La2—La1^xvii	55.545 (10)
Zn^i—La1—La2^iv	55.564 (18)	La1^xiii—La2—La1^xvii	68.91 (2)
Zn^ii—La1—La2^iv	97.94 (3)	La1^xiv—La2—La1^xvii	111.09 (2)
Zn^iii—La1—La2^iv	55.477 (10)	La1^xv—La2—La1^xvii	108.668 (10)
Sn^iv—La1—La2^iv	59.571 (13)	La1^viii—La2—La1^xvii	71.332 (10)
Sn^v—La1—La2^iv	146.931 (17)	La1^xvi—La2—La1^xvii	180.000 (16)
La1^vi—La1—La2^iv	108.903 (17)	Zn^x—Zn—La1^xviii	63.28 (2)
Zn^i—La1—La2^vii	97.94 (3)	Zn^x—Zn—La1^xvi	63.28 (2)
Zn^ii—La1—La2^vii	55.564 (18)	La1^xviii—Zn—La1^xvi	74.58 (3)
Zn^iii—La1—La2^vii	55.477 (10)	Zn^x—Zn—La1^xix	63.28 (2)
Sn^iv—La1—La2^vii	146.931 (17)	La1^xviii—Zn—La1^xix	82.05 (3)
Sn^v—La1—La2^vii	59.571 (13)	La1^xvi—Zn—La1^xix	126.56 (5)
La1^vi—La1—La2^vii	108.903 (17)	Zn^x—Zn—La1^xiv	63.28 (2)
La2^iv—La1—La2^vii	102.966 (18)	La1^xviii—Zn—La1^xiv	126.56 (5)
Zn^i—La1—La1^viii	52.712 (14)	La1^xvi—Zn—La1^xiv	82.05 (3)
Zn^ii—La1—La1^viii	52.712 (14)	La1^xix—Zn—La1^xiv	74.58 (3)
Zn^iii—La1—La1^viii	139.19 (2)	Zn^x—Zn—La1^xx	139.19 (2)
Sn^iv—La1—La1^viii	106.604 (9)	La1^xviii—Zn—La1^xx	140.29 (2)
Sn^v—La1—La1^viii	106.604 (9)	La1^xvi—Zn—La1^xx	140.29 (2)
La1^vi—La1—La1^viii	123.951 (19)	La1^xix—Zn—La1^xx	84.909 (18)
La2^iv—La1—La1^viii	105.084 (8)	La1^xiv—Zn—La1^xx	84.909 (18)
La2^vii—La1—La1^viii	105.084 (8)	Zn^x—Zn—La1^iii	139.19 (2)
Zn^i—La1—La1^xxvii	87.66 (2)	La1^xviii—Zn—La1^iii	84.909 (18)
Zn^ii—La1—La1^xxvii	113.473 (17)	La1^xvi—Zn—La1^iii	84.909 (18)
Zn^iii—La1—La1^xxvii	147.382 (8)	La1^xix—Zn—La1^iii	140.29 (2)
Sn^iv—La1—La1^xxvii	54.057 (10)	La1^xiv—Zn—La1^iii	140.29 (2)
Sn^v—La1—La1^xxvii	104.62 (2)	La1^xx—Zn—La1^iii	81.63 (4)
La1^vi—La1—La1^xxvii	70.91 (2)	Zn^x—Zn—La2^xxi	116.78 (2)
La2^iv—La1—La1^xxvii	98.861 (14)	La1^xviii—Zn—La2^xxi	70.228 (8)
La2^vii—La1—La1^xxvii	156.689 (9)	La1^xvi—Zn—La2^xxi	138.024 (12)
La1^viii—La1—La1^xxvii	60.762 (9)	La1^xix—Zn—La2^xxi	70.228 (8)
Zn^i—La1—La1^xxii	113.473 (17)	La1^xiv—Zn—La2^xxi	138.024 (12)
Zn^ii—La1—La1^xxii	87.66 (2)	La1^xx—Zn—La2^xxi	70.06 (2)
Zn^iii—La1—La1^xxii	147.382 (8)	La1^iii—Zn—La2^xxi	70.06 (2)
Sn^iv—La1—La1^xxii	104.62 (2)	Zn^x—Zn—La2^vii	116.78 (2)
Sn^v—La1—La1^xxii	54.057 (10)	La1^xviii—Zn—La2^vii	138.024 (12)
La1^vi—La1—La1^xxii	70.91 (2)	La1^xvi—Zn—La2^vii	70.228 (8)
La2^iv—La1—La1^xxii	156.689 (9)	La1^xix—Zn—La2^vii	138.024 (12)
La2^vii—La1—La1^xxii	98.861 (14)	La1^xiv—Zn—La2^vii	70.228 (8)
La1^viii—La1—La1^xxii	60.762 (9)	La1^xx—Zn—La2^vii	70.06 (2)
La1^xxvii—La1—La1^xxii	58.477 (18)	La1^iii—Zn—La2^vii	70.06 (2)
Zn^ix—La2—Zn^ii	180.0	La2^xxi—Zn—La2^vii	126.44 (4)
Zn^ix—La2—Zn^x	90.0	La1^xxii—Sn—La1^xvii	146.791 (18)
Zn^ii—La2—Zn^x	90.0	La1^xxii—Sn—La1^xiv	61.550 (18)
Zn^ix—La2—Zn^xi	90.0	La1^xvii—Sn—La1^xiv	129.77 (2)
Zn^ii—La2—Zn^xi	90.0	La1^xxii—Sn—La1^v	79.622 (8)
Zn^x—La2—Zn^xi	180.0	La1^xvii—Sn—La1^v	132.159 (17)
Zn^ix—La2—Sn^xii	90.0	La1^xiv—Sn—La1^v	71.89 (2)
Zn^ii—La2—Sn^xii	90.0	La1^xxii—Sn—La1^xxiii	129.77 (2)
Zn^x—La2—Sn^xii	90.0	La1^xvii—Sn—La1^xxiii	61.550 (18)
Zn^xi—La2—Sn^xii	90.0	La1^xiv—Sn—La1^xxiii	146.791 (18)
Zn^ix—La2—Sn	90.0	La1^v—Sn—La1^xxiii	79.622 (8)
Zn^ii—La2—Sn	90.0	La1^xxii—Sn—La1^xxiv	132.159 (17)
Zn^x—La2—Sn	90.0	La1^xvii—Sn—La1^xxiv	79.622 (8)
Zn^xi—La2—Sn	90.0	La1^xiv—Sn—La1^xxiv	79.622 (8)
Sn^xii—La2—Sn	180.0	La1^v—Sn—La1^xxiv	61.550 (18)
Zn^ix—La2—La1^xiii	54.461 (17)	La1^xxiii—Sn—La1^xxiv	71.89 (2)
Zn^ii—La2—La1^xiii	125.539 (17)	La1^xxii—Sn—La1^viii	71.89 (2)
Zn^x—La2—La1^xiii	125.792 (18)	La1^xvii—Sn—La1^viii	79.622 (8)
Zn^xi—La2—La1^xiii	54.208 (18)	La1^xiv—Sn—La1^viii	79.622 (8)
Sn^xii—La2—La1^xiii	55.544 (10)	La1^v—Sn—La1^viii	146.791 (18)
Sn—La2—La1^xiii	124.456 (10)	La1^xxiii—Sn—La1^viii	132.159 (17)
Zn^ix—La2—La1^xiv	125.539 (17)	La1^xxiv—Sn—La1^viii	129.77 (2)
Zn^ii—La2—La1^xiv	54.461 (17)	La1^xxii—Sn—La1^xxv	79.622 (8)
Zn^x—La2—La1^xiv	54.208 (18)	La1^xvii—Sn—La1^xxv	71.89 (2)
Zn^xi—La2—La1^xiv	125.792 (18)	La1^xiv—Sn—La1^xxv	132.159 (17)
Sn^xii—La2—La1^xiv	124.456 (10)	La1^v—Sn—La1^xxv	129.77 (2)
Sn—La2—La1^xiv	55.544 (10)	La1^xxiii—Sn—La1^xxv	79.622 (8)
La1^xiii—La2—La1^xiv	180.000 (16)	La1^xxiv—Sn—La1^xxv	146.791 (18)
Zn^ix—La2—La1^xv	54.208 (18)	La1^viii—Sn—La1^xxv	61.550 (18)
Zn^ii—La2—La1^xv	125.792 (18)	La1^xxii—Sn—La2^xxvi	64.885 (10)
Zn^x—La2—La1^xv	54.461 (17)	La1^xvii—Sn—La2^xxvi	115.115 (10)
Zn^xi—La2—La1^xv	125.539 (17)	La1^xiv—Sn—La2^xxvi	115.115 (10)
Sn^xii—La2—La1^xv	55.544 (10)	La1^v—Sn—La2^xxvi	64.885 (10)
Sn—La2—La1^xv	124.456 (10)	La1^xxiii—Sn—La2^xxvi	64.885 (10)
La1^xiii—La2—La1^xv	71.332 (10)	La1^xxiv—Sn—La2^xxvi	115.115 (10)
La1^xiv—La2—La1^xv	108.668 (10)	La1^viii—Sn—La2^xxvi	115.115 (10)
Zn^ix—La2—La1^viii	125.792 (18)	La1^xxv—Sn—La2^xxvi	64.885 (10)
Zn^ii—La2—La1^viii	54.208 (18)	La1^xxii—Sn—La2	115.115 (10)
Zn^x—La2—La1^viii	125.539 (17)	La1^xvii—Sn—La2	64.885 (10)
Zn^xi—La2—La1^viii	54.461 (17)	La1^xiv—Sn—La2	64.885 (10)
Sn^xii—La2—La1^viii	124.456 (10)	La1^v—Sn—La2	115.115 (10)
Sn—La2—La1^viii	55.544 (10)	La1^xxiii—Sn—La2	115.115 (10)
La1^xiii—La2—La1^viii	108.668 (10)	La1^xxiv—Sn—La2	64.885 (10)
La1^xiv—La2—La1^viii	71.332 (10)	La1^viii—Sn—La2	64.885 (10)
La1^xv—La2—La1^viii	180.000 (18)	La1^xxv—Sn—La2	115.115 (10)
Zn^ix—La2—La1^xvi	125.539 (17)	La2^xxvi—Sn—La2	180.0

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

 

Footnotes

‡Also at: Institute of Chemistry, Environmental Protection and Biotechnology, Jan Dlugosz University, Armii Krajowej 13/15 Ave., 42-200 Czestochowa, Poland.