supplementary materials


Acta Cryst. (2013). E69, i51    [ doi:10.1107/S1600536813019235 ]

Pentazirconium copper tribismuth

A. Balinska, I. Tarasiuk and V. Pavlyuk

Abstract top

Pentazirconium copper tribismuth, Zr5CuBi3, crystallizes in the hexagonal Hf5CuSn3 structure type. The asymmetric unit contains two Zr sites (site symmetries 3.2 and m2m), one Cu site (site symmetry 3.m) and one Bi site (site symmetry m2m). The environment of the Bi atoms is a tetragonal antiprism with one added atom and a coordination number (CN) of 9. The polyhedron around the Zr1 atom is a defective cubooctahedron with CN = 11. The bicapped hexagonal antiprism (CN = 14) is typical for Zr2 atoms. The Cu atom is enclosed in a eight-vertex polyhedron (octahedron with two centered faces). The metallic type of bonding was indicated by an analysis of the interatomic distances and electronic structure calculation data.

Comment top

Zirconium intermetallic compounds are extensively investigated for the last 40 years as possible hydrogen storage materials. The results that we present in this paper is a continuation of the systematic study that we carried out for zirconium alloys with transition metals (Giza et al., 2001; Dolotko et al., 2003) as well as s-and p-elements (Zatorska et al., 2002a,b; 2004; Giza et al., 2009). So far, in the literature no data on ternary intermetallic compounds of Zr—Cu—Bi system has been found. However, it is known that closely related systems such as Zr—Cu—Sn (Pöttgen, 1997), Zr—Cu—Pb (Rieger & Parthé, 1965) and Zr—Cu—Sb (Garcia & Corbett, 1990) form Zr5CuX3 (where X=Sn, Pb, Sb) compounds with hexagonal Hf5CuSn3 structure type (superstructure to Ti5Ga4-type) with space group P63/mcm. Studying alloys of the Zr—Cu—Bi system we found the existence of isostructural Zr5CuBi3 compound and investigated its structure by single-crystal method. The projection of the unit cell and coordination polyhedra of the atoms are shown in Fig. 1. The environment of the Bi atoms is a tetragonal antiprism with one added atom and a coordination number equal 9. The polyhedron of Zr1 atom is a defective cubooctahedron with a coordination number equal 11. The bicapped hexagonal antiprism (c.n.=14) is typical for Zr2 atom. The Cu atom is enclosed in a 8-vertex polyhedron (octahedron with two centered faces). The distribution of zirconium and copper atoms in three-dimensional-nets consisted of Bi atoms are shown in Fig. 2a and distribution of bismuth and copper atoms in three-dimensional-nets consisted of Zr atoms are shown in Fig. 2b. In the first case the Bi atoms form a 63 corrugated nets and the Zr atoms (second case) form a 3246 nets. The similar atomic nets was described for Tb5LiSn3 isostructural compound (Stetskiv et al., 2011).

The electronic structure of the Zr5CuBi3 compound was calculated using the tight-binding linear muffin-tin orbital (TB–LMTO) method in the atomic spheres approximation (TB– LMTO–ASA; Andersen, 1975; Andersen & Jepsen, 1984; Andersen et al., 1985, 1986), using the experimental crystallographic data which are presented here. The Zr and Cu atoms donate their electrons to the Bi atoms. Therefore positive charge density can be observed around the atoms of transition elements (Zr and Cu) and negative charge density is around the bismuth atoms. The electron localization function (ELF) mapping and isosurfaces (ISO) are presented in Fig. 3a and Fig. 3b, respectively. The total and partial densities of states (DOS) of Zr5CuBi3 compound calculated by the TB–LMTO–ASA method are shown in Fig. 4. The Fermi level (EF) lies in a continuous DOS region indicating a metallic character for the title compound. The metallic type of bonding was confirmed also by an analysis of the interatomic distances.

Related literature top

For general background, see: Dolotko et al. (2003); Giza et al. (2001, 2009); Zatorska et al. (2002a,b, 2004). For isostructural/isotypic structures, see: Garcia & Corbett (1990); Pöttgen (1997); Rieger & Parthé (1965); Stetskiv et al. (2011). For calculation of the electronic structure using the tight-binding linear muffin-tin orbital (TB–LMTO) method in the atomic spheres approximation, see: Andersen (1975); Andersen & Jepsen (1984); Andersen et al. (1985, 1986).

Experimental top

The title compound was prepared from elemental zirconium (foil, 0.25 mm thick 99.8 at.%, Aldrich), copper (powder, pure, POCH) and bismuth (granules, 99.5 at.%, POCH). The pieces of the pure metals with a stoichiometry Zr50Cu20Bi30 were pressed into pellet. The sample was melted in arc furnace under continuous argon flow. The losses in alloy composition during melting were checked by weight comparison of the initial mixtures and the alloys. Metallic grey prismatic crystals were found in a crushed alloy using a conventional light microscope.

Refinement top

The structure was solved after the analytical absorption correction. In the first stage of the refinement, the positions of the Zr, Cu and Bi atoms were obtained correctly by direct methods. After the last cycle of refinement the highest peak of 1.915 e/Å3 is at (0; 0.4552; 1/4) and 0.76 Å away from the Bi atom. The deepest hole -1.539 e/Å3 is at (0.2424; 0; 1/4) and 1.12 Å away from the same atom.

Computing details top

Data collection: CrysAlis CCD (Oxford Diffraction, 2008); cell refinement: CrysAlis CCD (Oxford Diffraction, 2008); data reduction: CrysAlis RED (Oxford Diffraction, 2008); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg, 2006); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures top
[Figure 1] Fig. 1. The projection of the unit cell and coordination polyhedra of the atoms.
[Figure 2] Fig. 2. The distribution of Zr and Cu atoms in three-dimensional-nets from Bi atoms (a) and distribution of Bi and Cu atoms in three-dimensional-nets from Zr atoms (b).
[Figure 3] Fig. 3. (a) The electron localization function (ELF) mapping and (b) isosurfaces of the electron localization function around the atoms for Zr5CuBi3.
[Figure 4] Fig. 4. Total and partial DOS (densities of states) for Zr5CuBi3.
Pentazirconium copper tribismuth top
Crystal data top
Zr5CuBi3Dx = 9.274 Mg m3
Mr = 1146.58Mo Kα radiation, λ = 0.71073 Å
Hexagonal, P63/mcmCell parameters from 185 reflections
Hall symbol: -P 6c 2θ = 2.7–27.4°
a = 8.8712 (4) ŵ = 72.54 mm1
c = 6.0246 (3) ÅT = 293 K
V = 410.60 (3) Å3Prism, metallic grey
Z = 20.08 × 0.04 × 0.02 mm
F(000) = 956
Data collection top
Oxford Diffraction Xcalibur3 CCD
diffractometer
193 independent reflections
Radiation source: fine-focus sealed tube185 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.136
Detector resolution: 0 pixels mm-1θmax = 27.4°, θmin = 2.7°
ω scansh = 1111
Absorption correction: analytical
(CrysAlis RED; Oxford Diffraction, 2008)
k = 1111
Tmin = 0.231, Tmax = 0.654l = 07
1713 measured reflections
Refinement top
Refinement on F20 restraints
Least-squares matrix: fullPrimary atom site location: structure-invariant direct methods
R[F2 > 2σ(F2)] = 0.023Secondary atom site location: difference Fourier map
wR(F2) = 0.041 w = 1/[σ2(Fo2) + (0.010P)2]
where P = (Fo2 + 2Fc2)/3
S = 0.87(Δ/σ)max < 0.001
193 reflectionsΔρmax = 1.92 e Å3
13 parametersΔρmin = 1.54 e Å3
Crystal data top
Zr5CuBi3Z = 2
Mr = 1146.58Mo Kα radiation
Hexagonal, P63/mcmµ = 72.54 mm1
a = 8.8712 (4) ÅT = 293 K
c = 6.0246 (3) Å0.08 × 0.04 × 0.02 mm
V = 410.60 (3) Å3
Data collection top
Oxford Diffraction Xcalibur3 CCD
diffractometer
193 independent reflections
Absorption correction: analytical
(CrysAlis RED; Oxford Diffraction, 2008)
185 reflections with I > 2σ(I)
Tmin = 0.231, Tmax = 0.654Rint = 0.136
1713 measured reflectionsθmax = 27.4°
Refinement top
R[F2 > 2σ(F2)] = 0.023Δρmax = 1.92 e Å3
wR(F2) = 0.041Δρmin = 1.54 e Å3
S = 0.87Absolute structure: ?
193 reflectionsAbsolute structure parameter: ?
13 parametersRogers parameter: ?
0 restraints
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
xyzUiso*/Ueq
Bi10.63082 (6)0.63082 (6)0.25000.00715 (19)
Zr10.26831 (17)0.26831 (17)0.25000.0083 (3)
Zr20.66670.33330.00000.0103 (4)
Cu10.00000.00000.00000.0102 (10)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Bi10.0060 (2)0.0060 (2)0.0098 (3)0.0033 (2)0.0000.000
Zr10.0075 (4)0.0075 (4)0.0102 (8)0.0039 (5)0.0000.000
Zr20.0132 (7)0.0132 (7)0.0045 (11)0.0066 (3)0.0000.000
Cu10.0106 (14)0.0106 (14)0.009 (3)0.0053 (7)0.0000.000
Geometric parameters (Å, º) top
Bi1—Zr1i2.9319 (6)Zr2—Zr2ii3.0123 (2)
Bi1—Zr1ii2.9319 (6)Zr2—Zr2viii3.0123 (2)
Bi1—Zr1iii3.1424 (5)Zr2—Bi1ix3.1896 (2)
Bi1—Zr1iv3.1424 (5)Zr2—Bi1ii3.1896 (2)
Bi1—Zr2v3.1896 (2)Zr2—Bi1vi3.1896 (2)
Bi1—Zr2ii3.1896 (2)Zr2—Bi1x3.1896 (2)
Bi1—Zr23.1896 (2)Zr2—Bi1iv3.1896 (2)
Bi1—Zr2iv3.1896 (2)Zr2—Zr1ii3.6126 (9)
Bi1—Zr13.2159 (17)Zr2—Zr1vi3.6126 (9)
Zr1—Cu12.8167 (13)Zr2—Zr1ix3.6126 (9)
Zr1—Cu1v2.8167 (13)Zr2—Zr1x3.6126 (9)
Zr1—Bi1vi2.9319 (6)Cu1—Zr1xi2.8167 (13)
Zr1—Bi1vii2.9319 (6)Cu1—Zr1ix2.8167 (13)
Zr1—Bi1iii3.1424 (5)Cu1—Zr1xii2.8167 (13)
Zr1—Bi1iv3.1424 (5)Cu1—Zr1xiii2.8167 (13)
Zr1—Zr2ii3.6126 (9)Cu1—Zr1xiv2.8167 (13)
Zr1—Zr2v3.6126 (9)Cu1—Cu1v3.0123 (2)
Zr1—Zr23.6126 (9)Cu1—Cu1xii3.0123 (2)
Zr1—Zr2iv3.6126 (9)
Zr1i—Bi1—Zr1ii89.35 (6)Zr2viii—Zr2—Bi1ix61.822 (2)
Zr1i—Bi1—Zr1iii78.32 (3)Zr2ii—Zr2—Bi1ii61.822 (2)
Zr1ii—Bi1—Zr1iii78.32 (3)Zr2viii—Zr2—Bi1ii118.178 (2)
Zr1i—Bi1—Zr1iv78.32 (3)Bi1ix—Zr2—Bi1ii88.460 (16)
Zr1ii—Bi1—Zr1iv78.32 (3)Zr2ii—Zr2—Bi1vi61.822 (2)
Zr1iii—Bi1—Zr1iv146.91 (6)Zr2viii—Zr2—Bi1vi118.178 (2)
Zr1i—Bi1—Zr2v72.20 (3)Bi1ix—Zr2—Bi1vi73.185 (10)
Zr1ii—Bi1—Zr2v145.409 (19)Bi1ii—Zr2—Bi1vi99.528 (3)
Zr1iii—Bi1—Zr2v69.571 (14)Zr2ii—Zr2—Bi1x118.178 (2)
Zr1iv—Bi1—Zr2v123.798 (7)Zr2viii—Zr2—Bi1x61.822 (2)
Zr1i—Bi1—Zr2ii145.409 (19)Bi1ix—Zr2—Bi1x99.528 (3)
Zr1ii—Bi1—Zr2ii72.20 (3)Bi1ii—Zr2—Bi1x73.185 (10)
Zr1iii—Bi1—Zr2ii69.571 (14)Bi1vi—Zr2—Bi1x170.093 (17)
Zr1iv—Bi1—Zr2ii123.798 (7)Zr2ii—Zr2—Bi1iv118.178 (2)
Zr2v—Bi1—Zr2ii106.815 (9)Zr2viii—Zr2—Bi1iv61.822 (2)
Zr1i—Bi1—Zr2145.409 (19)Bi1ix—Zr2—Bi1iv99.528 (3)
Zr1ii—Bi1—Zr272.20 (3)Bi1ii—Zr2—Bi1iv170.093 (17)
Zr1iii—Bi1—Zr2123.798 (7)Bi1vi—Zr2—Bi1iv88.460 (16)
Zr1iv—Bi1—Zr269.571 (14)Bi1x—Zr2—Bi1iv99.528 (3)
Zr2v—Bi1—Zr2137.327 (18)Zr2ii—Zr2—Bi161.822 (2)
Zr2ii—Bi1—Zr256.356 (5)Zr2viii—Zr2—Bi1118.178 (2)
Zr1i—Bi1—Zr2iv72.20 (3)Bi1ix—Zr2—Bi1170.093 (17)
Zr1ii—Bi1—Zr2iv145.409 (19)Bi1ii—Zr2—Bi199.528 (3)
Zr1iii—Bi1—Zr2iv123.798 (7)Bi1vi—Zr2—Bi199.528 (3)
Zr1iv—Bi1—Zr2iv69.571 (14)Bi1x—Zr2—Bi188.460 (16)
Zr2v—Bi1—Zr2iv56.356 (5)Bi1iv—Zr2—Bi173.185 (9)
Zr2ii—Bi1—Zr2iv137.327 (18)Zr2ii—Zr2—Zr1ii65.360 (7)
Zr2—Bi1—Zr2iv106.815 (10)Zr2viii—Zr2—Zr1ii114.640 (7)
Zr1i—Bi1—Zr1135.33 (3)Bi1ix—Zr2—Zr1ii139.216 (18)
Zr1ii—Bi1—Zr1135.33 (3)Bi1ii—Zr2—Zr1ii56.01 (2)
Zr1iii—Bi1—Zr1106.55 (3)Bi1vi—Zr2—Zr1ii127.097 (6)
Zr1iv—Bi1—Zr1106.55 (3)Bi1x—Zr2—Zr1ii54.600 (5)
Zr2v—Bi1—Zr168.664 (9)Bi1iv—Zr2—Zr1ii114.38 (2)
Zr2ii—Bi1—Zr168.664 (9)Bi1—Zr2—Zr1ii50.598 (19)
Zr2—Bi1—Zr168.664 (9)Zr2ii—Zr2—Zr1vi65.360 (7)
Zr2iv—Bi1—Zr168.664 (9)Zr2viii—Zr2—Zr1vi114.640 (7)
Cu1—Zr1—Cu1v64.65 (3)Bi1ix—Zr2—Zr1vi54.600 (5)
Cu1—Zr1—Bi1vi77.64 (3)Bi1ii—Zr2—Zr1vi50.598 (19)
Cu1v—Zr1—Bi1vi77.64 (3)Bi1vi—Zr2—Zr1vi56.01 (2)
Cu1—Zr1—Bi1vii77.64 (3)Bi1x—Zr2—Zr1vi114.38 (2)
Cu1v—Zr1—Bi1vii77.64 (3)Bi1iv—Zr2—Zr1vi139.216 (18)
Bi1vi—Zr1—Bi1vii150.65 (6)Bi1—Zr2—Zr1vi127.097 (6)
Cu1—Zr1—Bi1iii138.87 (4)Zr1ii—Zr2—Zr1vi103.844 (8)
Cu1v—Zr1—Bi1iii74.221 (13)Zr2ii—Zr2—Zr1ix114.640 (7)
Bi1vi—Zr1—Bi1iii94.137 (2)Zr2viii—Zr2—Zr1ix65.360 (7)
Bi1vii—Zr1—Bi1iii94.137 (2)Bi1ix—Zr2—Zr1ix56.01 (2)
Cu1—Zr1—Bi1iv74.221 (13)Bi1ii—Zr2—Zr1ix139.216 (18)
Cu1v—Zr1—Bi1iv138.87 (4)Bi1vi—Zr2—Zr1ix54.600 (5)
Bi1vi—Zr1—Bi1iv94.137 (2)Bi1x—Zr2—Zr1ix127.097 (6)
Bi1vii—Zr1—Bi1iv94.137 (2)Bi1iv—Zr2—Zr1ix50.598 (19)
Bi1iii—Zr1—Bi1iv146.91 (6)Bi1—Zr2—Zr1ix114.38 (2)
Cu1—Zr1—Bi1147.675 (17)Zr1ii—Zr2—Zr1ix164.10 (4)
Cu1v—Zr1—Bi1147.675 (17)Zr1vi—Zr2—Zr1ix89.71 (3)
Bi1vi—Zr1—Bi1104.67 (3)Zr2ii—Zr2—Zr1x114.640 (7)
Bi1vii—Zr1—Bi1104.67 (3)Zr2viii—Zr2—Zr1x65.360 (7)
Bi1iii—Zr1—Bi173.45 (3)Bi1ix—Zr2—Zr1x50.598 (19)
Bi1iv—Zr1—Bi173.45 (3)Bi1ii—Zr2—Zr1x54.600 (5)
Cu1—Zr1—Zr2ii134.725 (16)Bi1vi—Zr2—Zr1x114.38 (2)
Cu1v—Zr1—Zr2ii104.942 (7)Bi1x—Zr2—Zr1x56.01 (2)
Bi1vi—Zr1—Zr2ii57.205 (10)Bi1iv—Zr2—Zr1x127.097 (6)
Bi1vii—Zr1—Zr2ii146.09 (3)Bi1—Zr2—Zr1x139.216 (18)
Bi1iii—Zr1—Zr2ii55.829 (13)Zr1ii—Zr2—Zr1x89.71 (3)
Bi1iv—Zr1—Zr2ii103.75 (3)Zr1vi—Zr2—Zr1x64.19 (4)
Bi1—Zr1—Zr2ii55.32 (2)Zr1ix—Zr2—Zr1x103.844 (8)
Cu1—Zr1—Zr2v134.725 (16)Zr1—Cu1—Zr1xi180.00 (6)
Cu1v—Zr1—Zr2v104.942 (7)Zr1—Cu1—Zr1ix85.92 (2)
Bi1vi—Zr1—Zr2v146.09 (3)Zr1xi—Cu1—Zr1ix94.08 (2)
Bi1vii—Zr1—Zr2v57.205 (11)Zr1—Cu1—Zr1xii85.92 (2)
Bi1iii—Zr1—Zr2v55.829 (13)Zr1xi—Cu1—Zr1xii94.08 (2)
Bi1iv—Zr1—Zr2v103.75 (3)Zr1ix—Cu1—Zr1xii94.08 (2)
Bi1—Zr1—Zr2v55.32 (2)Zr1—Cu1—Zr1xiii94.08 (2)
Zr2ii—Zr1—Zr2v90.29 (3)Zr1xi—Cu1—Zr1xiii85.92 (2)
Cu1—Zr1—Zr2104.942 (7)Zr1ix—Cu1—Zr1xiii85.92 (2)
Cu1v—Zr1—Zr2134.725 (16)Zr1xii—Cu1—Zr1xiii180.00 (3)
Bi1vi—Zr1—Zr257.205 (10)Zr1—Cu1—Zr1xiv94.08 (2)
Bi1vii—Zr1—Zr2146.09 (3)Zr1xi—Cu1—Zr1xiv85.92 (2)
Bi1iii—Zr1—Zr2103.75 (3)Zr1ix—Cu1—Zr1xiv180.00 (3)
Bi1iv—Zr1—Zr255.829 (13)Zr1xii—Cu1—Zr1xiv85.92 (2)
Bi1—Zr1—Zr255.32 (2)Zr1xiii—Cu1—Zr1xiv94.08 (2)
Zr2ii—Zr1—Zr249.279 (13)Zr1—Cu1—Cu1v57.675 (17)
Zr2v—Zr1—Zr2110.65 (4)Zr1xi—Cu1—Cu1v122.325 (17)
Cu1—Zr1—Zr2iv104.942 (7)Zr1ix—Cu1—Cu1v122.325 (17)
Cu1v—Zr1—Zr2iv134.725 (16)Zr1xii—Cu1—Cu1v122.325 (17)
Bi1vi—Zr1—Zr2iv146.09 (3)Zr1xiii—Cu1—Cu1v57.675 (17)
Bi1vii—Zr1—Zr2iv57.205 (10)Zr1xiv—Cu1—Cu1v57.675 (17)
Bi1iii—Zr1—Zr2iv103.75 (3)Zr1—Cu1—Cu1xii122.325 (17)
Bi1iv—Zr1—Zr2iv55.829 (13)Zr1xi—Cu1—Cu1xii57.675 (17)
Bi1—Zr1—Zr2iv55.32 (2)Zr1ix—Cu1—Cu1xii57.675 (17)
Zr2ii—Zr1—Zr2iv110.65 (4)Zr1xii—Cu1—Cu1xii57.675 (17)
Zr2v—Zr1—Zr2iv49.279 (13)Zr1xiii—Cu1—Cu1xii122.325 (17)
Zr2—Zr1—Zr2iv90.29 (3)Zr1xiv—Cu1—Cu1xii122.325 (17)
Zr2ii—Zr2—Zr2viii180.0Cu1v—Cu1—Cu1xii180.0
Zr2ii—Zr2—Bi1ix118.178 (2)
Symmetry codes: (i) y+1, xy+1, z; (ii) x+y+1, x+1, z+1/2; (iii) x+1, y+1, z+1; (iv) x+1, y+1, z; (v) xy, x, z+1/2; (vi) y+1, xy, z; (vii) x+y, x+1, z+1/2; (viii) x+y+1, x+1, z1/2; (ix) y, x+y, z; (x) xy+1, x, z1/2; (xi) x, y, z; (xii) xy, x, z1/2; (xiii) x+y, x, z+1/2; (xiv) y, xy, z.

Experimental details

Crystal data
Chemical formulaZr5CuBi3
Mr1146.58
Crystal system, space groupHexagonal, P63/mcm
Temperature (K)293
a, c (Å)8.8712 (4), 6.0246 (3)
V3)410.60 (3)
Z2
Radiation typeMo Kα
µ (mm1)72.54
Crystal size (mm)0.08 × 0.04 × 0.02
Data collection
DiffractometerOxford Diffraction Xcalibur3 CCD
diffractometer
Absorption correctionAnalytical
(CrysAlis RED; Oxford Diffraction, 2008)
Tmin, Tmax0.231, 0.654
No. of measured, independent and
observed [I > 2σ(I)] reflections
1713, 193, 185
Rint0.136
(sin θ/λ)max1)0.648
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.023, 0.041, 0.87
No. of reflections193
No. of parameters13
No. of restraints0
Δρmax, Δρmin (e Å3)1.92, 1.54

Computer programs: CrysAlis CCD (Oxford Diffraction, 2008), CrysAlis RED (Oxford Diffraction, 2008), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), DIAMOND (Brandenburg, 2006).

Acknowledgements top

Financial support from the Ministry of Education and Science of Ukraine.

references
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