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1.  Penta­lanthanum zinc diplumbide, La5Zn1−xPb2+x (x ≃ 0.6) 
The title non-stoichiometric penta­lanthanum zinc diplumbide, La5Zn1−xPb2+x (x ≃ 0.6), was prepared from the elements in an evacuated silica ampoule. It adopts the Nb5Sn2Si-type structure (space group I4/mcm, Pearson symbol tI32), a ternary ordered superstructure of the W5Si3 type. Among the four independent crystallographic positions, three are fully occupied by La (Wyckoff 16k), La (4b), and Pb (8h) and one is occupied by a statistical mixture [occupancy ratio 0.394 (12):0.606 (12)] of Zn and Pb (4a). The structure is constructed by face-sharing 10-vertex polyhedra around the unmixed Pb sites. These fragments enclose channels of trans-face-sharing tetra­gonal anti­prisms occupied by the disordered Zn and Pb sites.
doi:10.1107/S1600536813033618
PMCID: PMC3914033  PMID: 24526938
2.  Thulium nickel/lithium distannide, TmNi1−xLixSn2 (x = 0.035) 
The quaternary thulium nickel/lithium distannide, TmNi1−xLixSn2 (x = 0.035), crystallizes in the ortho­rhom­bic LuNiSn2 structure type. The asymmetric unit contains three Tm sites, six Sn sites, two Ni sites and one Ni/Li site [relative occupancies = 0.895 (8):0.185 (8)]. Site symmetries are .m. for all atoms. The 17-, 18- and 19-vertex distorted pseudo-Frank–Kasper polyhedra are typical for all Tm atoms. Four Sn atoms are enclosed in a 12-vertex deformed cubo­octa­hedron, and another Sn atom is enclosed in a penta­gonal prism with three added atoms. A tricapped trigonal prism is typical for a further Sn atom. The coordination number for all Ni atoms and Ni/Li statistical mixtures is 12 (fourcapped trigonal prism [Ni/LiTm5Sn5]). Tm atoms form the base of a prism and Ni/Li atoms are at the centres of the side faces of an [SnTm6Ni/Li3] prism. These isolated prisms are implemented into three-dimensional-nets built out of Sn atoms. Electronic structure calculations using TB-LMTO-ASA suggest that the Tm and Ni/Li atoms form positively charged n[TmNi/Li]m+ polycations which compensate the negative charge of 2n[Sn]m− polyanions. Analysis of the inter­atomic distances and electronic structure calculations indicate the dominance of a metallic type of bonding.
doi:10.1107/S1600536813027335
PMCID: PMC3884236  PMID: 24454012
3.  Penta­zirconium copper tribismuth 
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.
doi:10.1107/S1600536813019235
PMCID: PMC3793669  PMID: 24109256
4.  Terbium (lithium zinc) distannide, TbLi1–xZnxSn2 (x = 0.2) 
The new terbium (lithium zinc) distannide, TbLi1–xZnxSn2 (x = 0.2) crystallizes in the ortho­rhom­bic CeNiSi2 structure type with space group Cmcm and Pearson symbol oS16. Of the four independent 4c atom positions (m2m site symmetry), three are fully occupied by individual atoms (two by Sn and one by Tb atoms) and the fourth is occupied by Li and Zn atoms with a statistical distribution. The Tb coordination polyhedron is a 21-vertex pseudo-Frank–Kasper polyhedron. One Sn atom is enclosed in a tricapped trigonal prism, the second Sn atom is in a cubocta­hedron and the statistically distributed (Li,Zn) site is in a tetra­gonal anti­prism with one added atom. Electronic structure calculations were used for the elucidation of reasons for and the ability of mutual substitution of lithium and transition metals. Positive charge density was observed around the rare earth atom and the Li and Zn atoms, the negative charge density in the proximity of the Sn atoms.
doi:10.1107/S1600536812002103
PMCID: PMC3274839  PMID: 22346792
5.  Redetermination of LaZn5 based on single crystal X-ray diffraction data 
The crystal structure of the already known binary title compound LaZn5 (lanthanum penta­zinc) (space group P6/mmm, Pearson symbol 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 crystal structure consists of three crytallographically distinct atoms. The La atom (Wyckoff site 1a, site symmetry 6/mmm) is surrounded by 18 Zn atoms and two La atoms. The coordination polyhedron around one of the Zn atoms (Wyckoff site 2c, site symmetry -6m2) is an icosa­hedron made up from three La and nine Zn atoms. The other Zn atom (Wyckoff site 3g, site symmetry 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.
doi:10.1107/S1600536811050987
PMCID: PMC3254268  PMID: 22259311
6.  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).
doi:10.1107/S1600536811042413
PMCID: PMC3246910  PMID: 22219730
7.  Penta­terbium lithium tris­tannide, Tb5LiSn3  
The new ternary phase penta­terbium lithium tris­tannide, Tb5LiSn3, crystallizes in the hexa­gonal Hf5CuSn3 structure type, which is a ‘filled’ version of the binary RE 5Sn3 phases (Mn5Si3-type) (RE is rare earth). The asymmetric unit contains two Tb sites (site symmetries 3.2 and m2m), one Li site (site symmetry .m) and one Sn site (site symmetry m2m). The 14-vertex Frank–Kasper polyhedra are typical for Li and Tb atoms. The environment of the Sn atom is a pseudo-Frank–Kasper polyhedron with a coordination number of 13 for the tin atom. One of the Tb atoms is enclosed in a 17-vertex polyhedron. The metallic type of bonding was indicated by an analysis of the inter­atomic distances.
doi:10.1107/S1600536811041328
PMCID: PMC3246906  PMID: 22219726
8.  LaZn12.37 (1), a zinc-deficient variant of the NaZn13 structure type 
The title compound (lanthanum dodecazinc), LaZn12.37 (1), is confirmed to be a nonstoichiometric (zinc-deficient) modification of the NaZn13 structure type, in which one Zn atom (Wyckoff site 8b, site symmetry m ) has a fractional site occupancy of 0.372 (11). The other Zn atom (96i, m) and the La atom (8a, 432) are fully occupied. The coordination polyhedra of the Zn atoms are distorted icosa­hedra, whereas the La atoms are surrounded by 24 Zn atoms, forming pseudo-Frank–Kasper polyhedra. Electronic structure calculations indicate that Zn—Zn bonding is much stronger than La—Zn bonding.
doi:10.1107/S1600536811028893
PMCID: PMC3212105  PMID: 22090807
9.  The new ternary phases of La3(Zn0.874Mg0.126)11 and Ce3(Zn0.863Mg0.137)11  
The La3(Zn0.874Mg0.126)11 and Ce3(Zn0.863Mg0.137)11 inter­metallic compounds are isostructural and crystallize in the ortho­rhom­bic La3Al11 structure type. Compared to the structure of La3Al11, in La3(Zn0.874Mg0.126)11, a significant decrease of 11.9% in the unit-cell b axis and and an increase in the other two directions, of 3.6% along a and 5.2% along c, are observed. Such an atypical deformation is caused by the closer packing of atoms in the unit cell due to atom shifts that reflect strengthening of metallic-type bonding.
The new ternary inter­metallic title compounds, namely trilanthanum undeca­(zinc/magnesium), La3(Zn0.874Mg0.126)11, (I), and tricerium undeca­(zinc/magnesium), Ce3(Zn0.863Mg0.137)11, (II), are isostructural and crystallize in the ortho­rhom­bic La3Al11 structure type. These three phases belong to the same structural family, the representative members of which may be derived from the tetra­gonal BaAl4 structure type by a combination of inter­nal deformation and multiple substitution. Compared to the structure of La3Al11, in (I), a significant decrease of 11.9% in the unit-cell b axis and an increase in the other two directions, of 3.6% along a and 5.2% along c, are observed. Such an atypical deformation is caused by the closer packing of atoms in the unit cell due to atom shifts that reflect strengthening of metallic-type bonding. This structural change is also manifested in a significant difference in the coordination around the smaller atoms at the 8l Wyckoff position (site symmetry m). The Al atom in La3Al11 is in a tricapped trigonal prismatic environment (coordination number 9), while the Zn atoms in (I) and (II) are situated in a tetra­gonal anti­prism with two added atoms (coordination number 10).
doi:10.1107/S0108270110002556
PMCID: PMC2855569  PMID: 20203390
10.  TbNb6Sn6: the first ternary compound from the rare earth–niobium–tin system 
The title compound, terbium hexa­niobium hexastannide, TbNb6Sn6, is the first ternary compound from the rare earth–niobium–tin system. It has the HfFe6Ge6 structure type, which can be analysed as an inter­growth of the Zr4Al3 and CaCu5 structures. All the atoms lie on special positions; their coordination geometries and site symmetries are: Tb (dodeca­hedron) 6/mmm; Nb (distorted icosa­hedron) 2mm; Sn (Frank–Caspar polyhedron, CN = 14–15) 6mm and m2; Sn (distorted icosa­hedron) m2. The structure contains a graphite-type Sn network, Kagome nets of Nb atoms, and Tb atoms alternating with Sn2 dumbbells in the channels.
doi:10.1107/S1600536810045964
PMCID: PMC3011672  PMID: 21589205
11.  2-[(2Z,3E)-2-Hy­droxy­imino-5-phenyl-2,3-dihydro-3-thienyl­idene]-2-phenyl­acetonitrile 
In the crystal structure of the title compound, C18H12N2OS, centrosymmetric dimers are stabilized both by van der Waals inter­actions and by two types of inter­molecular O—H⋯N hydrogen bonds. In addition, an intra­molecular C—H⋯S hydrogen bond is observed. The dihedral angles between the central ring and the two pendant phenyl rings are 7.4 (1) and 45.06 (9)°.
doi:10.1107/S1600536810024955
PMCID: PMC3007389  PMID: 21588254

Results 1-11 (11)