inorganic compounds
Redetermination of LaZn5 based on single crystal X-ray diffraction data
aDepartment of Inorganic Chemistry, Ivan Franko National University of Lviv, Kyryla i Mefodia str. 6, 79005 Lviv, Ukraine, and bInstitute of Chemistry, Environmental Protection and Biotechnology, Jan Dlugosz University, Armii Krajowej Ave. 13/15, 42-200 Czestochowa, Poland
*Correspondence e-mail: romaniuk@ua.fm
The 5 (lanthanum pentazinc) (space group P6/mmm, hP6, CaCu5 structure type) has been redetermined from single-crystal X-ray diffraction data. In contrast to previous determinations based on X-ray powder data [Nowotny (1942). Z. Metallkd. 34, 247–253; de Negri et al. (2008). Intermetallics, 16, 168–178], where unit-cell parameters and assignment of the structure type were reported, the present study reveals anisotropic displacement parameters for all atoms. The consists of three crytallographically distinct atoms. The La atom (Wyckoff site 1a, 6/mmm) is surrounded by 18 Zn atoms and two La atoms. The around one of the Zn atoms (Wyckoff site 2c, -6m2) is an icosahedron made up from three La and nine Zn atoms. The other Zn atom (Wyckoff site 3g, mmm) is surrounded by four La and eight Zn atoms. Bonding between atoms is explored by means of the TB–LMTO–ASA (tight-binding linear muffin-tin orbital atomic spheres approximation) program package. The positive charge density is localized around La atoms, and the negative charge density is around Zn atoms, with weak covalent bonding between the latter.
of the already known binary title compound LaZnRelated literature
For previous structural studies of the title compound, see: de Negri et al. (2008); Nowotny (1942). For general background, see: Andersen et al. (1986); Berche et al. (2009); Oshchapovsky et al. (2011a,b); Pavlyuk et al. (2009); Zelinska et al. (2004).
Experimental
Crystal data
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Data collection: APEX2 (Bruker, 2004); cell SAINT (Bruker, 2004); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg, 2006) and VESTA (Momma & Izumi, 2008); software used to prepare material for publication: publCIF (Westrip, 2010).
Supporting information
10.1107/S1600536811050987/wm2565sup1.cif
contains datablocks I, global. DOI:Structure factors: contains datablock I. DOI: 10.1107/S1600536811050987/wm2565Isup2.hkl
A small irregularly shaped single crystal of LaZn5 was selected by mechanical fragmentation of a sample with nominal composition LaZn4. The sample was prepared by mixing stoichiometric amounts of Zn and LaZn powders with subsequent pressing into a pellet. This pellet was sealed in an evacuated silica ampoule and annealed in a resistance furnace at 873 K for 30 days and subsequently quenched in cold water. No reaction between the alloy and the silica container was observed.
The highest peak of 1.11 e/Å3 is at (0; 0; 0.1905) and 0.81 Å away from the La1 atom. The deepest hole -0.71 e/Å3 is at (0; 0; 1/2) and 2.13 Å away from the same atom.
Data collection: APEX2 (Bruker, 2004); cell
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); molecular graphics: DIAMOND (Brandenburg, 2006) and VESTA (Momma & Izumi, 2008); software used to prepare material for publication: publCIF (Westrip, 2010).LaZn5 | Dx = 7.024 Mg m−3 |
Mr = 465.86 | Mo Kα radiation, λ = 0.71073 Å |
Hexagonal, P6/mmm | Cell parameters from 1123 reflections |
Hall symbol: -P 6 2 | θ = 4.3–27.5° |
a = 5.4654 (17) Å | µ = 36.05 mm−1 |
c = 4.2574 (15) Å | T = 296 K |
V = 110.13 (6) Å3 | Irregular shape, metallic grey |
Z = 1 | 0.04 × 0.02 × 0.02 mm |
F(000) = 207 |
Bruker APEXII CCD diffractometer | 73 independent reflections |
Radiation source: fine-focus sealed tube | 62 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.069 |
ϕ and ω scans | θmax = 27.5°, θmin = 4.3° |
Absorption correction: multi-scan (SADABS; Bruker, 2004) | h = −6→7 |
Tmin = 0.410, Tmax = 0.478 | k = −6→7 |
1123 measured reflections | l = −5→5 |
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)] = 0.018 | w = 1/[σ2(Fo2) + (0.P)2 + 0.1413P] where P = (Fo2 + 2Fc2)/3 |
wR(F2) = 0.037 | (Δ/σ)max < 0.001 |
S = 1.17 | Δρmax = 1.11 e Å−3 |
73 reflections | Δρmin = −0.71 e Å−3 |
9 parameters | Extinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
0 restraints | Extinction coefficient: 0.022 (4) |
0 constraints |
LaZn5 | Z = 1 |
Mr = 465.86 | Mo Kα radiation |
Hexagonal, P6/mmm | µ = 36.05 mm−1 |
a = 5.4654 (17) Å | T = 296 K |
c = 4.2574 (15) Å | 0.04 × 0.02 × 0.02 mm |
V = 110.13 (6) Å3 |
Bruker APEXII CCD diffractometer | 73 independent reflections |
Absorption correction: multi-scan (SADABS; Bruker, 2004) | 62 reflections with I > 2σ(I) |
Tmin = 0.410, Tmax = 0.478 | Rint = 0.069 |
1123 measured reflections |
R[F2 > 2σ(F2)] = 0.018 | 9 parameters |
wR(F2) = 0.037 | 0 restraints |
S = 1.17 | Δρmax = 1.11 e Å−3 |
73 reflections | Δρmin = −0.71 e Å−3 |
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 | ||
La1 | 0.0000 | 0.0000 | 0.0000 | 0.0099 (4) | |
Zn1 | 0.3333 | 0.6667 | 0.0000 | 0.0124 (4) | |
Zn2 | 0.5000 | 1.0000 | 0.5000 | 0.0121 (4) |
U11 | U22 | U33 | U12 | U13 | U23 | |
La1 | 0.0106 (4) | 0.0106 (4) | 0.0085 (6) | 0.0053 (2) | 0.000 | 0.000 |
Zn1 | 0.0146 (5) | 0.0146 (5) | 0.0081 (8) | 0.0073 (3) | 0.000 | 0.000 |
Zn2 | 0.0162 (5) | 0.0104 (6) | 0.0079 (6) | 0.0052 (3) | 0.000 | 0.000 |
La1—Zn1i | 3.1554 (10) | Zn1—Zn2xiii | 2.6496 (7) |
La1—Zn1ii | 3.1554 (10) | Zn1—Zn1i | 3.1554 (10) |
La1—Zn1iii | 3.1554 (10) | Zn1—La1xiv | 3.1555 (10) |
La1—Zn1 | 3.1555 (10) | Zn1—La1xv | 3.1555 (10) |
La1—Zn1iv | 3.1555 (10) | Zn1—Zn1xvi | 3.1555 (10) |
La1—Zn1v | 3.1555 (10) | Zn1—Zn1v | 3.1555 (10) |
La1—Zn2vi | 3.4640 (8) | Zn2—Zn1xvii | 2.6496 (7) |
La1—Zn2vii | 3.4640 (8) | Zn2—Zn1xvi | 2.6496 (7) |
La1—Zn2viii | 3.4640 (8) | Zn2—Zn1xviii | 2.6496 (7) |
La1—Zn2ix | 3.4640 (8) | Zn2—Zn2xix | 2.7327 (8) |
La1—Zn2iv | 3.4640 (8) | Zn2—Zn2viii | 2.7327 (8) |
La1—Zn2x | 3.4640 (8) | Zn2—Zn2xx | 2.7327 (8) |
Zn1—Zn2xi | 2.6496 (7) | Zn2—Zn2vi | 2.7327 (8) |
Zn1—Zn2 | 2.6496 (7) | Zn2—La1xxi | 3.4640 (8) |
Zn1—Zn2viii | 2.6496 (7) | Zn2—La1xiv | 3.4640 (8) |
Zn1—Zn2xii | 2.6496 (7) | Zn2—La1xv | 3.4640 (8) |
Zn1—Zn2vi | 2.6496 (7) | Zn2—La1xxii | 3.4640 (8) |
Zn1i—La1—Zn1ii | 120.0 | Zn2xiii—Zn1—La1xv | 72.679 (6) |
Zn1i—La1—Zn1iii | 180.0 | Zn1i—Zn1—La1xv | 60.0 |
Zn1ii—La1—Zn1iii | 60.0 | La1xiv—Zn1—La1xv | 120.0 |
Zn1i—La1—Zn1 | 60.0 | Zn2xi—Zn1—La1 | 72.679 (6) |
Zn1ii—La1—Zn1 | 180.0 | Zn2—Zn1—La1 | 126.545 (13) |
Zn1iii—La1—Zn1 | 120.0 | Zn2viii—Zn1—La1 | 72.679 (6) |
Zn1i—La1—Zn1iv | 60.0 | Zn2xii—Zn1—La1 | 126.545 (13) |
Zn1ii—La1—Zn1iv | 60.0 | Zn2vi—Zn1—La1 | 72.679 (5) |
Zn1iii—La1—Zn1iv | 120.0 | Zn2xiii—Zn1—La1 | 72.679 (6) |
Zn1—La1—Zn1iv | 120.0 | Zn1i—Zn1—La1 | 60.0 |
Zn1i—La1—Zn1v | 120.0 | La1xiv—Zn1—La1 | 120.0 |
Zn1ii—La1—Zn1v | 120.0 | La1xv—Zn1—La1 | 120.0 |
Zn1iii—La1—Zn1v | 60.0 | Zn2xi—Zn1—Zn1xvi | 107.321 (5) |
Zn1—La1—Zn1v | 60.0 | Zn2—Zn1—Zn1xvi | 53.455 (13) |
Zn1iv—La1—Zn1v | 180.0 | Zn2viii—Zn1—Zn1xvi | 107.321 (6) |
Zn1i—La1—Zn2vi | 46.905 (10) | Zn2xii—Zn1—Zn1xvi | 53.455 (13) |
Zn1ii—La1—Zn2vi | 133.095 (10) | Zn2vi—Zn1—Zn1xvi | 107.321 (6) |
Zn1iii—La1—Zn2vi | 133.095 (10) | Zn2xiii—Zn1—Zn1xvi | 107.321 (6) |
Zn1—La1—Zn2vi | 46.906 (10) | Zn1i—Zn1—Zn1xvi | 120.0 |
Zn1iv—La1—Zn2vi | 90.0 | La1xiv—Zn1—Zn1xvi | 60.0 |
Zn1v—La1—Zn2vi | 90.0 | La1xv—Zn1—Zn1xvi | 60.0 |
Zn1i—La1—Zn2vii | 133.095 (10) | La1—Zn1—Zn1xvi | 180.0 |
Zn1ii—La1—Zn2vii | 46.905 (10) | Zn2xi—Zn1—Zn1v | 53.455 (13) |
Zn1iii—La1—Zn2vii | 46.905 (10) | Zn2—Zn1—Zn1v | 107.321 (5) |
Zn1—La1—Zn2vii | 133.094 (10) | Zn2viii—Zn1—Zn1v | 53.455 (13) |
Zn1iv—La1—Zn2vii | 90.0 | Zn2xii—Zn1—Zn1v | 107.321 (6) |
Zn1v—La1—Zn2vii | 90.0 | Zn2vi—Zn1—Zn1v | 107.321 (6) |
Zn2vi—La1—Zn2vii | 180.0 | Zn2xiii—Zn1—Zn1v | 107.321 (6) |
Zn1i—La1—Zn2viii | 90.0 | Zn1i—Zn1—Zn1v | 120.0 |
Zn1ii—La1—Zn2viii | 133.094 (9) | La1xiv—Zn1—Zn1v | 60.0 |
Zn1iii—La1—Zn2viii | 90.0 | La1xv—Zn1—Zn1v | 180.0 |
Zn1—La1—Zn2viii | 46.906 (10) | La1—Zn1—Zn1v | 60.0 |
Zn1iv—La1—Zn2viii | 133.094 (10) | Zn1xvi—Zn1—Zn1v | 120.0 |
Zn1v—La1—Zn2viii | 46.906 (10) | Zn1—Zn2—Zn1xvii | 180.0 |
Zn2vi—La1—Zn2viii | 46.463 (8) | Zn1—Zn2—Zn1xvi | 73.09 (3) |
Zn2vii—La1—Zn2viii | 133.537 (8) | Zn1xvii—Zn2—Zn1xvi | 106.91 (3) |
Zn1i—La1—Zn2ix | 90.0 | Zn1—Zn2—Zn1xviii | 106.91 (3) |
Zn1ii—La1—Zn2ix | 46.906 (9) | Zn1xvii—Zn2—Zn1xviii | 73.09 (3) |
Zn1iii—La1—Zn2ix | 90.0 | Zn1xvi—Zn2—Zn1xviii | 180.0 |
Zn1—La1—Zn2ix | 133.094 (10) | Zn1—Zn2—Zn2xix | 121.043 (10) |
Zn1iv—La1—Zn2ix | 46.906 (10) | Zn1xvii—Zn2—Zn2xix | 58.958 (10) |
Zn1v—La1—Zn2ix | 133.094 (10) | Zn1xvi—Zn2—Zn2xix | 58.958 (10) |
Zn2vi—La1—Zn2ix | 133.537 (8) | Zn1xviii—Zn2—Zn2xix | 121.042 (10) |
Zn2vii—La1—Zn2ix | 46.463 (8) | Zn1—Zn2—Zn2viii | 58.957 (10) |
Zn2viii—La1—Zn2ix | 180.0 | Zn1xvii—Zn2—Zn2viii | 121.042 (11) |
Zn1i—La1—Zn2iv | 46.906 (9) | Zn1xvi—Zn2—Zn2viii | 121.042 (10) |
Zn1ii—La1—Zn2iv | 90.0 | Zn1xviii—Zn2—Zn2viii | 58.958 (10) |
Zn1iii—La1—Zn2iv | 133.094 (9) | Zn2xix—Zn2—Zn2viii | 180.0 |
Zn1—La1—Zn2iv | 90.0 | Zn1—Zn2—Zn2xx | 121.043 (10) |
Zn1iv—La1—Zn2iv | 46.906 (10) | Zn1xvii—Zn2—Zn2xx | 58.957 (10) |
Zn1v—La1—Zn2iv | 133.094 (10) | Zn1xvi—Zn2—Zn2xx | 58.957 (10) |
Zn2vi—La1—Zn2iv | 46.463 (8) | Zn1xviii—Zn2—Zn2xx | 121.043 (10) |
Zn2vii—La1—Zn2iv | 133.537 (8) | Zn2xix—Zn2—Zn2xx | 60.0 |
Zn2viii—La1—Zn2iv | 86.189 (19) | Zn2viii—Zn2—Zn2xx | 120.0 |
Zn2ix—La1—Zn2iv | 93.811 (19) | Zn1—Zn2—Zn2vi | 58.957 (10) |
Zn1i—La1—Zn2x | 133.094 (9) | Zn1xvii—Zn2—Zn2vi | 121.043 (10) |
Zn1ii—La1—Zn2x | 90.0 | Zn1xvi—Zn2—Zn2vi | 121.043 (10) |
Zn1iii—La1—Zn2x | 46.906 (9) | Zn1xviii—Zn2—Zn2vi | 58.957 (10) |
Zn1—La1—Zn2x | 90.0 | Zn2xix—Zn2—Zn2vi | 120.0 |
Zn1iv—La1—Zn2x | 133.094 (10) | Zn2viii—Zn2—Zn2vi | 60.0 |
Zn1v—La1—Zn2x | 46.906 (10) | Zn2xx—Zn2—Zn2vi | 180.0 |
Zn2vi—La1—Zn2x | 133.537 (8) | Zn1—Zn2—La1xxi | 119.585 (15) |
Zn2vii—La1—Zn2x | 46.463 (8) | Zn1xvii—Zn2—La1xxi | 60.416 (15) |
Zn2viii—La1—Zn2x | 93.811 (19) | Zn1xvi—Zn2—La1xxi | 119.585 (15) |
Zn2ix—La1—Zn2x | 86.189 (19) | Zn1xviii—Zn2—La1xxi | 60.415 (15) |
Zn2iv—La1—Zn2x | 180.0 | Zn2xix—Zn2—La1xxi | 66.768 (4) |
Zn2xi—Zn1—Zn2 | 145.358 (11) | Zn2viii—Zn2—La1xxi | 113.232 (4) |
Zn2xi—Zn1—Zn2viii | 106.91 (3) | Zn2xx—Zn2—La1xxi | 113.232 (4) |
Zn2—Zn1—Zn2viii | 62.09 (2) | Zn2vi—Zn2—La1xxi | 66.768 (4) |
Zn2xi—Zn1—Zn2xii | 62.09 (2) | Zn1—Zn2—La1xiv | 60.415 (15) |
Zn2—Zn1—Zn2xii | 106.91 (3) | Zn1xvii—Zn2—La1xiv | 119.584 (15) |
Zn2viii—Zn1—Zn2xii | 145.358 (11) | Zn1xvi—Zn2—La1xiv | 60.415 (15) |
Zn2xi—Zn1—Zn2vi | 145.358 (11) | Zn1xviii—Zn2—La1xiv | 119.585 (15) |
Zn2—Zn1—Zn2vi | 62.09 (2) | Zn2xix—Zn2—La1xiv | 113.232 (5) |
Zn2viii—Zn1—Zn2vi | 62.09 (2) | Zn2viii—Zn2—La1xiv | 66.768 (4) |
Zn2xii—Zn1—Zn2vi | 145.358 (11) | Zn2xx—Zn2—La1xiv | 66.768 (5) |
Zn2xi—Zn1—Zn2xiii | 62.09 (2) | Zn2vi—Zn2—La1xiv | 113.232 (4) |
Zn2—Zn1—Zn2xiii | 145.358 (11) | La1xxi—Zn2—La1xiv | 180.0 |
Zn2viii—Zn1—Zn2xiii | 145.358 (11) | Zn1—Zn2—La1xv | 60.415 (15) |
Zn2xii—Zn1—Zn2xiii | 62.09 (2) | Zn1xvii—Zn2—La1xv | 119.585 (15) |
Zn2vi—Zn1—Zn2xiii | 106.91 (3) | Zn1xvi—Zn2—La1xv | 60.416 (15) |
Zn2xi—Zn1—Zn1i | 107.321 (6) | Zn1xviii—Zn2—La1xv | 119.584 (15) |
Zn2—Zn1—Zn1i | 107.321 (6) | Zn2xix—Zn2—La1xv | 66.768 (4) |
Zn2viii—Zn1—Zn1i | 107.321 (6) | Zn2viii—Zn2—La1xv | 113.232 (4) |
Zn2xii—Zn1—Zn1i | 107.321 (6) | Zn2xx—Zn2—La1xv | 113.232 (4) |
Zn2vi—Zn1—Zn1i | 53.455 (13) | Zn2vi—Zn2—La1xv | 66.768 (4) |
Zn2xiii—Zn1—Zn1i | 53.455 (13) | La1xxi—Zn2—La1xv | 75.84 (3) |
Zn2xi—Zn1—La1xiv | 72.679 (6) | La1xiv—Zn2—La1xv | 104.16 (3) |
Zn2—Zn1—La1xiv | 72.679 (6) | Zn1—Zn2—La1xxii | 119.585 (15) |
Zn2viii—Zn1—La1xiv | 72.679 (6) | Zn1xvii—Zn2—La1xxii | 60.415 (15) |
Zn2xii—Zn1—La1xiv | 72.679 (6) | Zn1xvi—Zn2—La1xxii | 119.584 (15) |
Zn2vi—Zn1—La1xiv | 126.545 (13) | Zn1xviii—Zn2—La1xxii | 60.416 (15) |
Zn2xiii—Zn1—La1xiv | 126.545 (13) | Zn2xix—Zn2—La1xxii | 113.232 (4) |
Zn1i—Zn1—La1xiv | 180.0 | Zn2viii—Zn2—La1xxii | 66.768 (4) |
Zn2xi—Zn1—La1xv | 126.545 (13) | Zn2xx—Zn2—La1xxii | 66.768 (4) |
Zn2—Zn1—La1xv | 72.679 (6) | Zn2vi—Zn2—La1xxii | 113.232 (4) |
Zn2viii—Zn1—La1xv | 126.545 (13) | La1xxi—Zn2—La1xxii | 104.16 (3) |
Zn2xii—Zn1—La1xv | 72.679 (6) | La1xiv—Zn2—La1xxii | 75.84 (3) |
Zn2vi—Zn1—La1xv | 72.679 (6) | La1xv—Zn2—La1xxii | 180.0 |
Symmetry codes: (i) −x+1, −y+1, −z; (ii) −x, −y, −z; (iii) x−1, y−1, z; (iv) x, y−1, z; (v) −x, −y+1, −z; (vi) x−y+1, x, z; (vii) x−y, x−1, z−1; (viii) −y+1, x−y+1, z; (ix) −y+1, x−y, z−1; (x) x−1, y−1, z−1; (xi) −y+1, x−y+1, z−1; (xii) x, y, z−1; (xiii) x−y+1, x, z−1; (xiv) x, y+1, z; (xv) x+1, y+1, z; (xvi) −x+1, −y+2, −z; (xvii) −x+1, −y+2, −z+1; (xviii) x, y, z+1; (xix) −y+2, x−y+2, z; (xx) x−y+1, x+1, z; (xxi) x+1, y+1, z+1; (xxii) x, y+1, z+1. |
Experimental details
Crystal data | |
Chemical formula | LaZn5 |
Mr | 465.86 |
Crystal system, space group | Hexagonal, P6/mmm |
Temperature (K) | 296 |
a, c (Å) | 5.4654 (17), 4.2574 (15) |
V (Å3) | 110.13 (6) |
Z | 1 |
Radiation type | Mo Kα |
µ (mm−1) | 36.05 |
Crystal size (mm) | 0.04 × 0.02 × 0.02 |
Data collection | |
Diffractometer | Bruker APEXII CCD diffractometer |
Absorption correction | Multi-scan (SADABS; Bruker, 2004) |
Tmin, Tmax | 0.410, 0.478 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 1123, 73, 62 |
Rint | 0.069 |
(sin θ/λ)max (Å−1) | 0.650 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.018, 0.037, 1.17 |
No. of reflections | 73 |
No. of parameters | 9 |
Δρmax, Δρmin (e Å−3) | 1.11, −0.71 |
Computer programs: APEX2 (Bruker, 2004), SAINT (Bruker, 2004), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), DIAMOND (Brandenburg, 2006) and VESTA (Momma & Izumi, 2008), publCIF (Westrip, 2010).
Acknowledgements
Financial support from the Ministry of Education and Science, Youth and Sport of Ukraine (No. 0111U001089) is gratefully acknowledged.
References
Andersen, K., Povlovska, Z. & Jepsen, O. (1986). Phys. Rev. B, 34, 51–53. CrossRef Web of Science Google Scholar
Berche, A., Record, M.-C. & Rogez, J. (2009). Open Thermodynam. J. 3, 7–16. CrossRef CAS Google Scholar
Brandenburg, K. (2006). DIAMOND. Crystal Impact GbR, Bonn, Germany. Google Scholar
Bruker (2004). SADABS, APEX2 and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Momma, K. & Izumi, F. (2008). J. Appl. Cryst. 41, 653–658. Web of Science CrossRef CAS IUCr Journals Google Scholar
Negri, S. de, Solokha, P., Saccone, A. & Pavlyuk, V. (2008). Intermetallics, 16, 168-178. Google Scholar
Nowotny, H. (1942). Z. Metallkd. 34, 247–253. CAS Google Scholar
Oshchapovsky, I., Pavlyuk, V., Dmytriv, G., Chumak, I. & Ehrenberg, H. (2011b). Acta Cryst. E67, i65. Web of Science CrossRef IUCr Journals Google Scholar
Oshchapovsky, I., Pavlyuk, V., Dmytriv, G. & White, F. (2011a). Acta Cryst. E67, i43. Web of Science CrossRef IUCr Journals Google Scholar
Pavlyuk, V., Oshchapovsky, I. & Marciniak, B. (2009). J. Alloys Compd, 477, 145–148. Web of Science CrossRef CAS Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Westrip, S. P. (2010). J. Appl. Cryst. 43, 920–925. Web of Science CrossRef CAS IUCr Journals Google Scholar
Zelinska, O., Conrad, M. & Harbrecht, B. (2004). Z. Kristallogr. New Cryst. Struct. 219, 357–358. CAS Google Scholar
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This paper is part of a systematic investigation of binary RE—Zn (Oshchapovsky et al., 2011a; Zelinska et al., 2004) and ternary RE—Zn—M systems (where RE is a rare earth metal and M is a p-element of group IV) (Oshchapovsky et al., 2011b; Pavlyuk et al., 2009). The binary La—Zn system is not completely investigated yet (Berche et al., 2009), especially with respect to the structure of the compound LaZn4. In order to determine its crystal structure a sample with the same composition was synthesized. However, this sample was prepared under non-equilibrium conditions and phase analysis from X-ray powder data revealed the presence of LaZn5, LaZn2, trace amounts of LaZn and strong reflections of unknown phase(s). The lattice parameters of the title LaZn5 phase were determined for the first time based on X-ray powder diffraction data (Nowotny, 1942). Previous authors (Nowotny, 1942; de Negri et al., 2008) also assigned the structure type. However, a complete crystal structure determination including anisotropic displacement parameters was not carried out before. Therefore a high-quality single-crystal of LaZn5 was selected and the results of the full structure determination are presented in this paper.
The crystal structure consists of three crytallographically distinct atoms. La1 (Wyckoff site 1a, site symmetry 6/mmm) is surrounded by 18 Zn atoms and 2 La atoms. The coordination polyhedron around Zn1 atom (Wyckoff site 2c, site symmetry -6m2) is an icosahedron formed by 3 La and 9 Zn atoms. Zn2 (Wyckoff site 3g, site symmetry mmm) is surrounded by 4 La and 8 Zn atoms. The projection of the LaZn5 unit cell is given in Fig. 1. The thermal displacement of the lanthanum atom is almost isotropic. The thermal ellipsoids of the Zn1 atoms are oblate along the c axis. The thermal ellipsoids of the Zn2 atoms are extended along the a and b axes due to the largest space for displacement in this direction (the distances of corresponding atoms to each other and to La atoms are larger than for Zn1 atoms).
The electronic structure of LaZn5 was calculated using the TB-LMTO-ASA package (Andersen et al., 1986). The dominant type of bonding in this compound is metallic. The La atoms donate their electrons to the Zn atoms. Therefore positive charge density can be observed around the rare earth atom and negative charge density is around the transition metal atoms. This fact, together with significant electron density (~0.4 e/Å3) and significant ELF density (~0.4) between Zn atoms, confirms the weak covalent bonding between them. In other words, an ion–metallic bonding between La and Zn atoms and a covalent–metallic bonding between Zn atoms is evident (Figure 2). A similar way of bond formation is also observed for LaZn12.37 (Oshchapovsky et al., 2011a) and La5Zn2Sn (Oshchapovsky et al., 2011b) which were investigated previously. The density of states (DOS) plot confirms a metallic-type of conductivity of the title compound (Figure 3), and it is rather similar to the DOS plot for the LaZn12.37 compound.