Crystal structure of Ba2La4Ti5O18, member n = 6 of the homologous series (Ba,La)nTin−1O3n of cation deficient perovskite-related compounds

Ba₂La₄Ti₅O₁₈ crystallizes in the trigonal system (space group R3) with the unit-cell parameters: a = 5.584 (1) Å; c = 41.176 (8) Å; Z= 3.The structure has been solved from single crystal X-ray diffraction data to a final R₁ = 0.0285. Ba and La atoms are twelve-fold coordinated and Ti atoms six-fold coordinated. The structure can be described as consisting of identical perovskite-like blocks, five corner-sharing TiO₆ octahedra thick, separated by layers of vacant octahedra. The distortion of the cation and anion sublattices has been analysed and a Ba/La order has been evidenced.     

La5Al3Ni2 – an Intermetallic Phase Observed upon Crystallization of La50Al25Ni25 Metallic Glass

The yet unknown intermetallic phase La₅Al₃Ni₂ was obtained by partially crystallizing amorphous La₅₀Al₂₅Ni₂₅ at 550 K (further heating above 600 K leads to irreversible disappearance of this phase), and its crystal structure was determined from X‐ray powder diffraction data. The crystal structure of the La₅Al₃Ni₂ phase constitutes a new structure type (Cmcm, a = 14.231Å, b = 6.914Å, c = 10.460Å, oC40) and is built from [Al₃Ni₂] chains surrounded by La atoms. In the ternary system La‐Al‐Ni La₅Al₃Ni₂ is located on the section La₅₀Al_50−nNi_n (0 ≤ n ≤ 50) with the binary compounds LaAl and LaNi as end members. Strikingly, also the crystal structures of the end members can be conceived as chain structures with Al and Ni chains surrounded by La, respectively.     

Neue ternäre Phosphide und Arsenide mit einem Metall : Nichtmetall‐Verhältnis im Bereich von 2 : 1

New Ternary Phosphides and Arsenides with a Metal : Non‐Metal Ratio in the Range of 2 : 1 Six new compounds were prepared by heating mixtures of the elements or by reaction of them in a tin(lead) flux. They were investigated by single crystal X‐ray methods. Sc₂Ni₁₂P₇ (a = 9.013(1), c = 3.590(1) Å) crystallizes in the Zr₂Fe₁₂P₇ type structure (P6; Z = 1), which is basically built up likewise by Eu₂Pd₁₂As₇ (a = 10.040(1), c = 4.100(1) Å) and Sr₂Rh₁₂P₇ (a = 9.626(1), c = 3.844(1) Å), but one of seven non‐metal atoms has a somewhat modified environment and is disordered along [001]. Therefore their crystal structure corresponds to the Ho₂Rh₁₂As₇ type structure (P6₃/m; Z = 1). Ca₂Ni₇P₄ (a = 3.703(1), b = 9.209(1), c = 10.378(1) Å) forms the Nd₂Ni₇P₄ type structure (Pmn2₁; Z = 2), whereas the atomic arrangements of Ca₄Rh₁₃As₉ (a = 3.903(2), b = 11.221(1), c = 19.411(4) Å) and Sm₄Rh₁₃As₉ (a = 3.913(2), b = 11.242(6), c = 19.440(6) Å) correspond basically to the Ho₄Ir₁₃Ge₉ type structure (Pmmn; Z = 2), but the disorder of Rh8 required the occupation of splitting positions. The transition metals have three, four or five neighbouring atoms of phosphorus or arsenic and form together with them three‐dimensional covalent frameworks, of which holes are occupied by the atoms of the electropositive metal. Most of the polyhedra around the P and As atoms respectively consist of trigonal prisms of metal atoms with additional metal atoms capping the rectangular faces of the prisms. This environment ist characteristic for ternary phosphides and arsenides with a metal : non‐metal ratio in the range of 2 : 1.     

Ternäre Nickelphosphide und -arsenide mit einem Metall: Nichtmetall-Verhältnis von 2:1

Ternary Phosphides and Arsenides of Nickel with a Metal: Non-Metal Ratio of 2:1 Several new ternary phosphides and arsenides of nickel were prepared by reaction of the elements. SrNi₅P₃, SrNi₅As₃, and EuNi₅As₃ crystallize in the LaCo₅P₃ structure with the following lattice constants [Å]: BaNi₉P₅ (a = 6.534(1) Å, c = 10.847(2) Å) and BaNi₉As₅ (a = 6.760(1) Å, c = 11.226(2) Å) crystallize in a new type of structure (P6₃/mmc, Z = 2). The characteristic polyhedra are trigonal Ni-antiprisms centered by P or As atoms and trigonal Ni-prisms with vacant centres and sides capped by non-metal atoms. U₂Ni₁₂P₇ (a = 9.077(2) Å, c = 3.694(1) Å) has a Zr₂Fe₁₂P₇ structure (P6 , Z = 1).     

Über die Kristallstruktur der Phase La5B2C6

On the Crystal Structure of the Phase La₅B₂C₆ A homogeneous sample of La₅B₂C₆ annealed at 1000 °C was investigated by X‐ray powder and single‐crystal as well as electron diffraction. The crystal structure was refined in space group P4/ncc (a = 8.590(1) Å, b = 12.398(1) Å, Z = 4, ρ_calc = 5.723 g/cm, ρ_exp = 5.70 g/cm) allowing for anharmonic displacement parameters for the metal atoms. The structure contains twofold disordered CBCC units in bicapped tetragonal antiprismatic coordination in contrast to C₂ and CBC units in earlier investigations.     

Synthesis and Crystal Structures of Tris-[3, 5-bis(trifluoromethyl)phenyl]arsine Oxide at 293 and 100 K and the Localization of the Trifluoromethyl Groups

Tris[3, 5-bis(trifluoromethyl)phenyl]arsine oxide ( 1 ) was synthesised by oxidation of tris[3, 5-bis(trifluoromethyl)phenyl]arsine with hydrogen peroxide in acetone. At 293 K, it crystallizes in the trigonal space group R3c (a = 20.2947(12) Å, c = 11.2484(13) Å, Z = 6, R₁ = 0.0254). The compound undergoes a phase transition upon cooling, and it crystallizes in the monoclinic space group Cc at 100 K (a = 13.8621(13) Å, b = 18.6537(17) Å, c = 11.2874(10) Å, Z = 4, R₁ = 0.0444). The crystal structures of both phases were determined. The fluorine atoms of the trifluoromethyl groups are strongly disordered at room temperature, which probably indicates a rotational motion in the plane of the fluorine atoms. This motion slows down while lowering the temperature, and the fluorine atoms are localized at 100 K. This point is illustrated by comparison of the experimental electron densities at the CF₃ groups. The packing pattern in both structures consists of parallel columns of ecliptically stacked molecules. The columns are hexagonally arranged.     

Single Crystal X‐ray Structure Investigation and Electronic Structure Studies of La‐Deficient Nickel Stannide La4.87Ni12Sn24 Grown from Sn Flux

The cubic La_4.87Ni₁₂Sn₂₄ was synthesized in reactions involving liquid Sn. The compound crystallizes in the cubic syngony, space group Im3¯, Z = 2, cell parameter a = 11.9662(14) Å, and is related to the Gd₃Ni₈Sn₁₆ structure type previously refined from powder X‐ray data. The crystal structure of La_4.87Ni₁₂Sn₂₄ was solved and refined using single crystal X‐ray data to final R₁ = 2.67%, wR₂ = 6.92%. The refinement showed no mixed occupancy with Sn for the La(1) site, contrary to what was proposed for Gd₃Ni₈Sn₁₆. Instead, a partial occupancy of 87% was detected for the La(1) at 2a. Electronic structure calculations show that the system is metallic, and the density of states at the Fermi level falls at a peak with the highest contribution coming from La(1) atoms, if the compound with ideal occupancies La₅Ni₁₂Sn₂₄ is assumed. The deficiency of the La(1) site could therefore originate in the lowering of the total energy of the system due to the loss of 0.39 electrons per formula unit. Magnetic measurement data indicates nearly temperature independent Pauli paramagnetism. Theoretical estimation of the magnetic susceptibility after including core diamagnetic corrections agrees well with experiment.     

La6(BN3)O6, ein Nitridoborat‐Oxid des Lanthans

La₆(BN₃)O₆, a Nitridoborate Oxide of Lanthanum Single‐crystals of La₆(BN₃)O₆ were formed in reactions of Li₃BN₂, Li₃N, and LaOCl at 950 °C. The structure was solved by single‐crystal X‐ray diffraction. La₆(BN₃)O₆crystallizes with the space group Cmcm (no. 63) containing Z = 4 formula units in the unit cell, with lattice parameters of a = 366.88(3) pm, b = 2509.2(3) pm, and c = 1101.1(1) pm (R1 = 0.054, wR2 = 0.065 for all collected symmetry independant reflections). The crystal structure reflects typical patterns obtained in structures of nitridoborates. Tri‐nitridoborate ions are coordinated by La³⁺ ions in a tricapped trigonal prismatic arrangement, being stacked via shared trigonal faces to form columns. The arrangement of the columns in the structure provides space for O^2— ions with CN = 4, 5, and 6.     

Investigation of mixed divalent cation phosphates: synthesis and X-ray powder structure determination of CdBa2(P2O7)(HPO4)

Hydrothermal synthesis, characterization by X-ray diffraction, IR absorption, TGA and ab-initio crystal structure determination are reported for a new phosphate CdBa₂(P₂O₇)(HPO₄). It crystallizes in a monoclinic cell (space group Im, No. 8, Z=2) with a=11.9022(1) Å, b=5.5530(1) Å, c=7.3401(1) Å, β=90.091(1)°. The X-ray powder diffraction pattern was fitted by the Rietveld method technique with reliability R_Bragg=0.037. Hydrogen atoms could not be located. The crystal structure of CdBa₂(P₂O₇)(HPO₄) is built up from P₂O₇ diphosphate groups sharing four oxygen atoms with two CdO₆ trigonal prisms. Each CdO₆ trigonal prism shares one edge with the HPO₄ unit. Such an arrangement builds up isolated infinite chains CdP₃O₁₁ running along the b axis. Ba²⁺ ions are inserted between these chains in the (b,c) plane.     

Structure de La2Fe2S5 et de La2Fe1.87S5

The compound La₂Fe₂S₅ is orthorhombic. Cell parameters are: a = 3.997(2)Å; b = 16.485(5)Å; c = 11.394(4)Å. Space group is Cmc2₁ (Z = 4. In the cell, chains of polyedra comprised of sulfur atoms tetrahedrally or octahedrally coordinating centrally located iron atoms give a monodimensional character to the structure. This one is refined to R = 0.037. To complete the study of these chains, in the La₂Fe_2?xS₅ system, vacancies are introduced on iron atom sites. The ordered compound, La₂Fe_1.87S₅, having such vacancies, is an orthorhombic superstructure of the stoechiometric compound. Cell parameters are: a = 3.9996(5)Å; b = 49.508(3)Å; c = 11.308(3)Å. Space group is Cmc2₁ and Z = 12. The structure is refined to R = 0.068. Only two iron atom sites have vacancies. One is tetrahedral, the other octahedral. In this last case the chain deformations are the more important. The chain becomes a sort of tunnel made of atoms of sulfur, with in its center the short iron-iron separation of 2.82 Å.     

La2Pb(SiS4)2

Crystals of La₂Pb(SiS₄)₂, dilanthanum(III) lead(II) bis[tetrasulfidosilicate(IV)], were obtained from the La–Pb–Si–S system and structurally characterized using X‐ray single‐crystal diffraction. The La and Pb atoms are coordinated in bicapped trigonal prisms of S atoms, with the Si atoms in tetrahedra. An occupational disorder of the La and Pb centres was refined for one position in the structure. The bicapped trigonal prisms and tetrahedra share edges. A gap located 2.629 (1) Å from the sulfide anions was found around the coordination polyhedra, which makes La₂Pb(SiS₄)₂ a prospective material in crystal engineering. The Si and one S atom lie on a threefold axis.     

Crystal and molecular structure of methyl(±)-2-((1R,3R)-3-{ 2-[(3S)-1-ethyl-3-hydroxy-2-oxo-2,3-dihydro-1H-3-indolyl]acetyl}-2,2-dimethylcyclobutyl) acetate

The structure of methyl (±)-2-((1R,3R)-3-{ 2-[(3S)-1-ethyl-3-hydroxy-2-oxo-2,3-dihydro-1H-3-indolyl]acetyl}-2,2-dimethylcyclobutyl) acetate has been determined by single crystal X-ray diffraction. The crystal belongs to triclinic system; parameters of the unit cell are: a = 6.551(1) Å, b = 11.506(1) Å, c = 14.334(1) Å, α = 101.41(1)°, β = 97.57(1)°, γ = 104.72(1)°; space group P-1, Z = 2, composition C₂₁H₂₇NO₅. The structure of N-ethyloxindole fragment is usual for the present class of compounds. The configuration of the formed asymmetric carbon atom C(3) of the pyrrole ring along with the configuration of C(12) and C(14) atoms of 2,2-dimethylcyclobutane ring form the side chain of the molecule were determined. There is observed the generation of centrosymmetrical dimers in the crystal structure due to realized intermolecular hydrogen bond of O-H...O type, 2.808(2) Å.     

Cristallochimie de TlIII6TeVIO12 et TlI6TeVIO6E6: un exemple original de l'activite´ste´re´ochimique de la pairee´lectronique 6s2(E) du thallium(I)

Both crystal structures of Tl₆TeO₁₂ and Tl₆TeO₆E₆ compounds have been determined, the former by X-ray single crystal techniques, the latter by powder neutron diffraction techniques. They crystallize in the trigonal system, space groupR3¯ the corresponding hexagonal cell parameters area = 9.645(2) Å,c = 9.421(2) Å, anda = 9.5722(3) Å,c = 9.3494(4) Å, respectively, withZ = 3. In both compounds tellurium(VI) is octahedrally coordinated to oxygen atoms with TeO distances of 1.936Åfor the Tl(III)-containing compound, i.e., Tl₆TeO₁₂, and 1.946Åfor Tl₆TeO₆ (Tl(I)). Tl(III) is surrounded by seven oxygen atoms sitting at the summits of a distorted monocapped trigonal prism. Tl(I) is linked to three oxygen atoms, forming a distorted TlO₃ pyramid. The lone pairs brought by Tl(I) are in the positions precedingly occupied by oxygen atoms in the crystal structure of Tl₆TeO₁₂. This is an outstanding example of the crystallochemical role of the lone pairsE which act like oxygen atoms, making Tl^I₆Te^VIO₆E₆ isostructural with Tl^IIITe^VIO₁₂. Structural relationships with fluorite type network are discussed.     

The Structure,Characterization, and Magnetic Properties of Ca4–xNixIrO6 (x = 0.25, 0.5)

Ca_4–xNi_xIrO₆ (x = 0.25, 0.5) crystallizes with trigonal (rhombohedral) symmetry in the space group R3¯c, Z = 6, for Ca_3.75Ni_0.25IrO₆ a = 9.3013(1) Å, c = 11.1554(1) Å; for Ca_3.5Ni_0.5IrO₆ a = 9.2723(1) Å, c = 11.0825(1) Å. Ca_3.75Ni_0.25IrO₆ and Ca_3.5Ni_0.5IrO₆ are isotypic to compounds of the Sr₄PtO₆ structure type. The structure of Ca_3.75Ni_0.25IrO₆ has been solved by means of single crystal X-ray diffraction data analysis with the reliability factors of R = 0.019 and R_w = 0.022. Also, both structures have been determined by Rietveld refinement of powder X-ray diffraction data. The structure consists of chains of alternating face-sharing IrO₆ octahedra and (Ca/Ni)O₆ trigonal prisms. The chains are separated by the calcium cations which are in a distorted square antiprismatic coordination. Magnetic measurements revealed that both Ca_3.75Ni_0.25IrO₆ and Ca_3.5Ni_0.5IrO₆ follow Curie-Weiss behavior at high temperatures. Ca_3.75Ni_0.25IrO₆ undergoes a single antiferromagnetic transition at T_N = 5 K whereas Ca_3.5Ni_0.5IrO₆ undergoes two antiferromagnetic transitions at T_N1 = 13 K and T_N2 = 4 K.     

The chemistry and the stereochemistry of poly(n-alkyliminoalanes) : III. The crystal and molecular structure of the adduct (HalN-i-Pr)6AlH3

The crystal and molecular structure of the adduct (HAlN-i-Pr)₆AlH₃ has been determined from single-crystal and three dimensional X-ray diffraction data collected by counter methods. The cage-type molecular structure consists of two six-membered rings, (AlN)₃, joined together by four adjacent transverse AlN bonds; the loss of two of these bonds allows the complexation of one alane molecule, with five-coordination of the aluminum (trigonal bipyramidal geometry), through two AlN bonds and two AlHAl bridge bonds. The AlN bond lengths range from 1.873 to 1.959 Å; the average AlH bond length is 1.50(1) Å for the four-coordinated aluminum atoms; the average distance of the two apical hydrogens from the five-coordinated aluminum atom is 1.92(5) Å. Colourless prismatic crystals of the compound have the following crystal data: triclinic space group P$\text{1}$; a = 17.13(2); b = 10.78(2); c = 10.20(2) Å; α = 124.3(4), β = 92.0(4), γ = 92.1(5); Z = 2; calculated density 1.157 g/cm³. The structure has been refined by block-matrix, least-squares methods using 4358 independent reflections to a standard unweighted R factor of 4.9%.     

The crystal structure of Sm4Ni11In20 and its relation to other indium-rich compounds

Polycrystalline Sm₄Ni₁₁In₂₀ was obtained by arc-melting of metal ingots. A subsequent high temperature treatment was used for single crystal growth. The Sm₄Ni₁₁In₂₀ crystal structure (U₄Ni₁₁Ga₂₀ type; C2/m, a = 22.5457(3) Å, b = 4.34929(5) Å, c = 16.5479(2) Å, β = 124.592(2)°, R1 = 0.0358, wR2 = 0.0934) was determined by single crystal synchrotron radiation X-ray diffraction from 2014 independent reflections with I > 2σ(I). Sm₄Ni₁₁In₂₀ extends the R ₄Ni₁₁In₂₀ (R = Y, Gd, Tb, Dy, Ho) series of phases. The R ₄Ni₁₁In₂₀ and RNi₃In₆ (LaNi₃In₆ type; R = La, Ce, Pr, Nd, Eu) series have similar compositions. Their structures share similar fragments; in particular the rare earth atom coordination polyhedra are pentagonal prisms with additional atoms.      

Neue Erdalkalimetall‐Phosphide und ‐Arsenide des Cobalts

New Alkaline‐Earth Metal Phosphides and Arsenides of Cobalt Five new compounds of cobalt were prepared by heating mixtures of the elements and investigated by means of single crystal X‐ray methods. Mg₂Co₁₂As₇ (a = 12.096(6), b = 3.670(2), c = 24.93(1) Å) crystallizes in a new structure type (Pnma; Z = 4). Most of the Co atoms are coordinated tetrahedrally by arsenic, the other ones in the form of a square pyramid. Due to the linking of these polyhedra channels of hexagonal cross section are formed along [010], in which the Mg atoms are arranged. Mg₂Co₁₂P₇ (a = 9.012(2), c = 3.504(1) Å), Ca₂Co₁₂P₇ (a = 9.073(1), c = 3.585(1) Å) as well as Ca₂Co₁₂As₇ (a = 9.428(5), c = 3.728(2) Å) crystallize in the Zr₂Fe₁₂P₇ structure type (P6; Z = 1). Micro domains of the arsenide required refinements of the structure parameters in space group P6₃/m. MgCo₆P₄ (a = 6.609(1), c = 3.380(1) Å) is isotypic with LiCo₆P₄ (P6m2; Z = 1). The compounds belong to the large family of phosphides and arsenides with a metal : non‐metal ratio of about 2 : 1. Their structures can be described by the linkings of non‐metal centred trigonal prisms of metal atoms with additional metal atoms capping the rectangular faces of the prisms.     

Synthese und Kristallstrukturen ternärer Phosphide und Arsenide des Rhodiums und Iridiums

Ternary Phosphides and Arsenides of Rhodium and Iridium: Synthesis and Crystal Structures Single crystals of eight new compounds were prepared by heating mixtures of the elements in a lead flux. They were investigated by X‐ray methods. Ca₂Ir₁₂P₇ (a = 9.512(1), c = 3.923(1) Å)is an additional representative of the Zr₂Rh₁₂P₇ type structure, micro domains required refinements of the structural parameters in space group P6₃/m. Ca₅Rh₁₉P₁₂ (a = 12.592(1), c = 3.882(1) Å) and Ca₅Ir₁₉P₁₂ (a = 12.577(2), c = 3.954(1) Å) crystallize with the Ho₅Ni₁₉P₁₂ type structure (P6¯2m; Z = 1), whereas the compounds A₆Rh₃₀X₁₉ form a slightly modified structure of the Yb₆Co₃₀P₁₉ type. The lattice constants are: Ca₆Rh₃₀P₁₉: a = 15.532(1) Å, c = 3.784(1) Å Sr₆Rh₃₀As₁₉: a = 16.135(2) Å, c = 3.916(1) Å Eu₆Rh₃₀P₁₉: a = 15.566(1) Å, c = 3.821(1) Å Eu₆Rh₃₀As₁₉: a = 16.124(1) Å, c =5 3.903(3) Å Yb₆Rh₃₀P₁₉: a = 5 15.508(1) Å, c =5 3.770(1) Å Because one of the four non‐metal atoms, located on different crystallographic sites, is disordered along [001] micro domains are formed. Therefore the parameters were not refined in space group P6¯ (Yb₆Rh₃₀P₁₉ type), but in space group P6₃/m. The metal:non‐metal ratio of all compounds is in the range of 2:1. Accordingly most of the non‐metal atoms are coordinated by nine metal atoms, which form tricapped trigonal prisms. These polyhedra are combined with each other in a different way.     

A novel mononuclear gold(I) complex: Synthesis and x-ray structure of [Au{P(C6H5)3}3][SiF5] · 1.5 CH2Cl2

Tris(triphenylphosphine)gold(I)-pentafluorosilicate(IV) ([Au{P(C₆H₅)₃}₃][SiF₅]) was prepared and the structure was determined by single crystal x-ray diffraction. The complex crystallizes in the triclinic space group P1 (No. 2). The lattice constants are a = 14.634(2) Å, b = 17.180(2) Å, c = 22.212(3) Å, α = 86.48(1)°, β = 78.95(1)°, γ = 83.99(1)°. Number of molecules per cell: Z = 4. The gold atoms are coordinated to three triphenylphosphine ligands to form the trigonal planar cation [Au{P(C₆H₅)₃}₃]⁺. Separated from the cation is the [SiF₅]^? anion which is regular trigonal bipyramidal coordinated. No interactions between the fluorine atoms and the gold atoms were observed.     

X-ray powder structure determination of Li6P6O18·3H2O

Preparation, characterization by X-ray diffraction, IR absorption, DTA-GTA analysis and ab-initio crystal structure determination are reported for a new lithium cyclohexaphosphate hydrate Li₆P₆O₁₈·3H₂O. It crystallizes in a trigonal (rhomboedral) cell (space group R 3¯m No 166, Z = 6) with a = 15.7442(2) Å, c = 12.5486(2) Å. X-ray powder diffraction pattern data was refined by Rietveld profile technique and lead to R_Bragg = 0.09. The crystal structure of Li₆P₆O₁₈·3H₂O is built up from [P₆O₁₈]^6- ring anions, having the 3m symmetry, alternating along the 3¯ axis with rings made of six LiO₄ tetrahedra and six LiO₅ pseudo square pyramids sharing common edges.