Zur Kristallstruktur von Tb2Se3

Crystal Structure of Tb₂Se₃ Single crystals of Tb₂Se₃ could be prepared by chemical transport reaction with AlCl₃. By starting from TbSe_1.9 and terbium metal black needles of Tb₂Se₃ in the U₂S₃ type structure with the space group Pnma and a = 1113,0(1) pm, b = 402,4(1) pm and c = 1095,1(3) pm were obtained.     

Synthese und Kristallstruktur von Ln2SeSiO4 (Ln = Sm,Dy, Ho) und Sm2TeSiO4

Synthesis and Crystal Structure of Ln₂SeSiO₄ (Ln = Sm, Dy, Ho) and Sm₂TeSiO₄ Single crystals of Ln₂SeSiO₄ (Ln = Sm, Dy, Ho) could be prepared by the reaction of lanthanide metal, selenium and iodine in the ratio 1 : 1 : 2.5 and subsequent reaction with quartz glass powder. Black crystals of Sm₂TeSiO₄ have been obtained in chemical transport experiments of SmTe₂ with iodine in evacuated quartz glass ampoules as by‐products. All chalcogenide silicates crystallize orthorhombically with the space group Pbcm (Z = 4) and the lattice constants: Sm₂SeSiO₄: a = 612.6(1) pm, b = 709.0(1) pm, c = 1094.0(2) pm; Dy₂SeSiO₄: a = 603.6(1) pm, b = 696.4(1) pm, c = 1081.2(2) pm; Ho₂SeSiO₄: a = 601.0(1) pm, b = 693.6(1) pm, c = 1078.6(2) pm; Sm₂TeSiO₄: a = 623.82(8) pm, b = 713.06(7) pm, c = 1112.26(11) pm. The crystal structure is built up of alternating Ln(Se/Te) and LnSiO₄ sheets parallel (001).     

Beiträge zur Kristallchemie der Urantelluride. I. Die Kristallstruktur des α-Urantritellurids

Contributions to the Crystal Chemistry of Uranium Tellurides. I. The Crystal Structure of α-Uranium Tritelluride Single crystals of the title compound up to a size of 8 mm were available via chemical transport reactions with TeBr₄ as transporting agent starting from the elements. The analysis by atomic emission spectrometry gave UTe_3.0(1). By X-ray single crystal structure analysis we found that UTe₃ crystallizes monoclinic (space group P 2₁/m, Z = 2) with a = 609.7(1) pm, b = 422.06(4) pm, c = 1031.2(1) pm and β = 97.87(1)º in the ZrSe₃-structure type. The layer structure is built up by bicapped trigonal prisms.     

The Unique Crystal Structure of the Triclinic Samarium(III) Oxoselenate(IV) Sm2[SeO3]3

Pale yellow, needle‐shaped single crystals of Sm₂[SeO₃]₃ were obtained by heating stoichiometric mixtures of Sm₂O₃ and SeO₂ (molar ratio: 1:3) along with substantial amounts of CsCl as fluxing agent in evacuated sealed silica tubes at 830 °C for one week. According to X‐ray single‐crystal diffraction data, Sm₂[SeO₃]₃ crystallizes triclinic (space group: ) with two formula units per unit cell of the dimensions a = 698.62(7), b = 789.71(8), c = 910.34(9) pm, α = 96.693(5), β = 104.639(5), γ = 115.867(5)°. Its crystal structure contains two crystallographically distinct Sm³⁺ cations in eight‐ and ninefold coordination with oxygen atoms arranged as distorted uncapped or capped square antiprisms (d(Sm³⁺?O^2?) = 232?271 pm). These [(Sm1)O₈] and [(Sm2)O₉] polyhedra share opposite edges and faces to form zigzag chains along [100] with discrete pyramidal [SeO₃]^2? anions bridging units. Further linkage by [SeO₃]^2? anions in [010] direction leads to a three‐dimensional network, which exhibits almost rectangular channels along [111]. These tunnels offer width enough to incorporate the free non‐bonding electron pairs (?lone pairs”?) at the Se⁴⁺ cations, since all nine different Ψ¹‐tetrahedral [SeO₃]^2? groups (d(Se⁴⁺?O^2?) = 165?173 pm, ?(O–Se–O) = 94 – 108°) exhibit a pronounced stereochemical ?lone‐pair”? activity. For not being isotypic with neither triclinic Er₂[SeO₃]₃ (CN(Er³⁺) = 7 and 8) nor the remainder rare‐earth metal(III) oxoselenates(IV) of the composition M₂[SeO₃]₃ (≡ M₂Se₃O₉; M = Sc, Y, La, Ce – Lu), Sm₂[SeO₃]₃ claims a unique crystal structure among them.     

Sm2Se5O13: A Selenite–Diselenite according to Sm2(SeO3)(Se2O5)2

Pale yellow single crystals of Sm₂(SeO₃)(Se₂O₅)₂ (monoclinic, P2₁/c, Z = 4, a = 1003.6(2), b = 1022.5(2), c = 1287.3(2) pm, β = 112.3(2)°) were obtained from the reaction of Sm₂O₃ and SeO₂ at 350 °C in a sealed glass ampoule. In the crystal structure both Se₂O₅^2? and SeO₃^2? groups connect the Sm³⁺ ions into layers. Between the layers the lone electron pairs of the anions are located.     

Single Crystals of C–La2Se3, C–Pr2Se3, and C–Gd2Se3 with Cation‐Deficient Th3P4‐Type Structure

Ruby‐red, bead‐shaped single crystals of C‐type La₂Se₃ (a = 905.21(6) pm), Pr₂Se₃ (a = 891.17(6) pm), and Gd₂Se₃ (a = 872.56(5) pm) are obtained by oxidation of the respective rare‐earth metal (M = La, Pr and Gd) with selenium (molar ratio 2 : 3) in evacuated silica tubes at 750 °C in the presence of fluxing CsCl within seven days. Their crystal structure belongs to a cation‐deficient Th₃P₄‐type variant (cubic, I 4 3d) according to M_2.667□_0.333Se₄ (Z = 4) or M₂Se₃ (Z = 5.333) offering coordination numbers of eight (Se^2– arranged as trigonal dodecahedra) to the M³⁺ cations. In spite of the high Cs⁺ activity in molten CsCl, no cesium incorporation into the M_5.333□_0.667Se₈‐frame structure (e. g. as CsM₅Se₈ with Z = 2) could be achieved, judged from both results of electron beam X‐ray microanalyses and refined occupation factors of the metal position very close to x = 8/9 for M_3xSe₄.     

Darstellung und Kristallstruktur der Hexaselenodiphosphate(IV) von Antimon und Bismut

Preparation and Crystal Structure of the Hexaselenodiphosphates(IV) of Antimony and Bismuth Sb₄(P₂Se₆)₃ and Bi₄(P₂Se₆)₃ are synthesized from the elements via chemical transport reactions with iodine. The isotypic compounds crystallize in the monoclinic space group P2₁/n (No. 14) with lattice parameters a = 2 077.7(4) pm, b = 749.35(5) pm, c = 949.49(8) pm, β = 91.25(1)° for Sb₄(P₂Se₆)₃ and a = 2 086.9(3) pm, b = 747.45(6) pm, c = 959.23(6) pm, β = 91.73(1)° for Bi₄(P₂Se₆)₃, respectively. This new structure type is closely related to the structure of Pb₂P₂Se₆ showing an ordered cation distribution combined with a reorientation of the ethane like [P₂Se₆]^4? units. From the interatomic distances in the coordination spheres a smaller lone pair effect of Bi^III compared to Sb^III may be deduced. For both compounds UV/VIS spectra and temperature dependence of the electrical resistivity are reported.     

Über Sesquiselenide der Lanthanoide: Einkristalle von Ce2Se3 im C‐, Gd2Se3 im U‐ und Lu2Se3 im Z‐Typ

On Sesquiselenides of the Lanthanoids: Single Crystals of C‐type Ce₂Se₃, U‐type Gd₂Se₃, and Z‐type Lu₂Se₃ Single crystals of lanthanoid sesquiselenides (M₂Se₃; here: M = Ce, Gd, Lu) are accessible through conversion of the elements (lanthanoid and selenium) in molar ratios of 2:3 within seven days at 850 °C from evacuated silica ampoules if equimolar amounts of NaCl serve as a flux. In the case of Ce₂Se₃ (a = 897.74(6) pm) und Gd₂Se₃ (a = 872.56(5) pm) the cubic C‐type (I4¯3d, Z = 5.333) forms as dark red beads, whereas the orthorhombic Z‐type (Fddd, Z = 16) emerges for Lu₂Se₃ (a = 1125.1(1), b = 798.06(8), c = 2387.7(2) pm) as orange‐yellow bricks. Upon oxidation of monochloride hydrides (MClH_x or A_yMClH_x; M = Ce, Gd, Lu; x = 1; A = Li, Na; y = 0.5) with selenium in arc‐welded tantalum ampoules the same main products appear with C‐Ce₂Se₃ and Z‐Lu₂Se₃, even with a surplus of NaCl or LiCl as fluxing agent. In the case of Gd₂Se₃, however, black‐red needles of the orthorhombic U‐type (Pnma, Z = 4; a = 1118.2(1), b = 403.48(4); c = 1097.1(1) pm) are yielded instead of C‐Gd₂Se₃. C‐Ce₂Se₃ crystallizes in a cation‐deficient Th₃P₄‐type structure (Ce₂S₃ type) according to Ce_2.667□_0.333Se₄ (Z = 4) or with Z = 5.333 for the empirical formula Ce₂Se₃. Here, Ce³⁺ is coordinated by eight Se^2— anions trigon‐dodecahedrally. In U‐Gd₂Se₃ (U₂S₃ type) two crystallographically independent Gd³⁺ cations with coordination numbers of 7 (Gd1) and 7+1 (Gd2), respectively, are present, exhibiting mono‐ or bicapped trigonal prisms as coordination polyhedra. The crystal structure of Z‐Lu₂Se₃ (Sc₂S₃ type) shows two different Lu³⁺ cations as well, which now both reside in octahedral coordination of six Se^2— anions each.     

Bridging Nonaselenium Ring in [Se9(IrBr3)2], and Three Modifications of the Mononuclear Complex [IrBr3(SeBr2)3]

The reaction of iridium powder with an excess of selenium and SeBr₄ yielded lustrous, vermillion crystals of the mononuclear iridium complex [IrBr₃(SeBr₂)₃]. The transition metal is coordinated octahedrally by three SeBr₂ and three bromide ligands with facial or meridional configuration. Three different modifications were obtained under similar conditions: a‐fac‐IrBr₃(SeBr₂)₃, space group P$\bar{1}$ , with a = 789.4(1) pm, b = 830.4(1) pm, c = 1334.4(1) pm, α = 81.634(5)°, β = 84.948(5)°, γ = 67.616(4)°; m‐fac‐IrBr₃(SeBr₂)₃, space group P2₁/n, with a = 1205.3(1) pm, b = 962.4(1) pm, c = 1383.9(1) pm, β = 91.114(3)°; mer‐IrBr₃(SeBr₂)₃, space group P2₁/n with a = 859.7(1) pm, b = 1284.3(1) pm, c = 1437.5(1) pm, β = 94.427(3)°. A lower bromine content in the starting composition resulted in shiny, deep‐red crystals of [Se₉(IrBr₃)₂]. X‐ray diffraction on a single‐crystal revealed a tetragonal lattice (space group I4₁/a) with a = 1245.4(1) pm and c = 2486.8(1) pm at 296(1) K. In the [Se₉(IrBr₃)₂] complex, a crown‐shaped uncharged Se₉ ring coordinates two iridium(III) cations as a bridging bis‐tridentate ligand. Three terminal bromide ions complete the distorted octahedral coordination of each transition metal atom.     

Pr30Ti24I8O25Se58: Eine hochsymmetrische Struktur mit isolierten [Ti6(O)Se8]‐Clustereinheiten

Pr₃₀Ti₂₄I₈O₂₅Se₅₈: A Highly Symmetric Structure with Isolated [Ti₆(O)Se₈]‐Cluster Units Black crystals of Pr₃₀Ti₂₄I₈O₂₅Se₅₈ have been prepared by the reaction of Pr₂Se₃, Pr₂O₂Se, TiSe_2–x, and I₂ at 900 °C. Its crystal structure can be described as a variation of the NaCl structure type (space group Fm 3 m, a = 2319.91(15) pm, Z = 4). The compound contains the first example of a [Ti₆(O)Se₈] cluster. These clusters form a cubic close packing, where the octahedral and tetrahedral holes are occupied by “superoctahedral” and “supertetrahedral” building units, respectively.     

Quaternäre Caesium‐Kupfer(I)‐Lanthanoid(III)‐Selenide vom Typ CsCu3M2Se5 (M = Sm,Gd — Lu)

Quaternary Cesium Copper(I) Lanthanoid(III) Selenides of the Type CsCu₃M₂Se₅ (M = Sm, Gd — Lu) By oxidation of mixtures of copper and lanthanoid metal with elemental selenium in molar ratios of 1 : 1 : 2 and in addition of CsCl quaternary cesium copper(I) lanthanoid(III) selenides with the formula CsCu₃M₂Se₅ (M = Sm, Gd — Lu) were obtained at 750 °C within a week from torch‐sealed evacuated silica tubes. An excess of CsCl as flux helps to crystallize golden yellow or red, needle‐shaped, water‐resistant single crystals. The crystal structure of CsCu₃M₂Se₅ (M = Sm, Gd — Lu) (orthorhombic, Cmcm, Z = 4; e. g. CsCu₃Sm₂Se₅: a = 417.84(3), b = 1470.91(8), c = 1764.78(9) pm and CsCu₃Lu₂Se₅: a = 407.63(3), b = 1464.86(8), c = 1707.21(9) pm, respectively) contains [MSe₆]^9— octahedra which share edges to form double chains running along [100]. Those are further connected by vertices to generate a two‐dimensional layer parallel to (010). By edge‐ and vertex‐linking of [CuSe₄]^7— tetrahedra two crystallographically different Cu⁺ cations build up two‐dimensional puckered layers parallel to (010) as well. These sheet‐like structure interconnects the equation/tex2gif-stack-3.gif{[M₂Se₅]^4—} layers to create a three‐dimensional network according to equation/tex2gif-stack-4.gif{[Cu₃M₂Se₅]^—}. Thus empty channels along [100] form, apt to take up the Cs⁺ cations. These are surrounded by eight plus one Se^2— anions in the shape of (2+1)‐fold capped trigonal prisms with Cs—Se distances between 348 and 368 pm (8×) and 437 (for M = Sm) or 440 pm (for M = Lu), respectively, for the ninth ligand.     

Die Kristallstrukturen von ErSeI und NaErSe2

The Crystal Structures of ErSeI and NaErSe₂ It is reported about attempts to synthesize lanthanoide selenidehalides of the formula LnSeX (X ? Cl, Br, I) exemplary for Ln ? Er. The relative stabilities of these compounds are discussed. X-ray crystal structure analysis revealed for the compounds ErSeBr and ErSeI the FeOCl-structure type (space group Pmmn, Z = 2, a = 406.3(5) pm, b = 559.2(6) pm, and c = 795(1) pm, and a = 418.26(6) pm, b = 558.4(1) pm, and c = 889.0(2) pm, respectively). A corresponding chloride was not found within the scope of this investigation. From the educts Er₂Se₃ and ErCl₃ in the presence of NaCl as flux in Nb-ampoules the compound NaErSe₂ was formed instead which crystallizes in an α-NaFeO₂-type structure (space group R3 m, Z = 3, a = 408.41(2) pm and c = 2067.4(2) pm).     

Synthese und Kristallstruktur von [Se3N2Cl]+ GaCl4−

Synthesis and Crystal Structure of [Se₃N₂Cl]⁺GaCl₄^? [Se₃N₂Cl]⁺GaCl₄^? has been prepared by the reduction of [Se₂NCl₂]⁺GaC1₄^? with SbPh₃ in CH₂Cl₂ solution, forming red crystals, which were characterized by an X-ray structure determination. Space group P2₁/n, Z = 4, 1640 observed unique reflections, R = 0.050. Lattice dimensions at ? 80 °C: a = 929.4(1), b= 1078.8(1), c = 1135.7(1) pm, β = 92.026(9)°. The cations from nearly planar Se₃N₂ five membered rings with Se? N bond lengths from 170 to 176pm and a Se? Se bond of 242.2 pm. One of the selenium atoms is bonded to the chlorine atom.     

Compounds in the system Cu2SeAs2Se3

The phase diagram Cu₂SeAs₂Se₃ was investigated by thermal and X-ray methods. Cu₂Se has a limited solubility for As₂Se₃ (5 mole% at 769 K). The stoichiometric compound Cu₃AsSe₃ exists between 696 and 769 K. Cu₄As₂Se₅, a phase at 66.6 mole% Cu₂Se, decomposes peritectically at 746 K. The narrow homogeneity range (4 mole% at 683 K) extends far into the ternary space. CuAsSe₂ also decomposes peritectically at 683 K. A degenerated eutectic between CuAsSe₂ and As₂Se₃ was found at 641 K. Single crystals of Cu₄As₂Se₅ were grown in a salt melt. A metastable modification of the high-temperature phase Cu₃AsSe₃ can be obtained by quenching. Cu₄As₂Se₅ (space group R3, lattice constants a = 1404.0(1) pm, c = 960.2(1) pm), Cu₆As₄Se₉, obtained by Cambi and Elli, and Cu₇As₆Se₁₃ of Takeuchi and Horiuchi are different versions of a sphalerite-type compound with a broad homogeneity range in the system CuAsSe. CuAsSe₂ is possibly monoclinic with lattice parameters of a = 946.5(1) pm, b = 1229.3(1) pm, c = 511.7(1) pm, and β = 98.546(4)°. The enthalpy of mixing of Cu₂Se and As₂Se₃ in the liquid state is endothermic.     

Synthese und Kristallstruktur einer neuen Modifikation von Tetraselentetranitrid,Se4N4

Synthesis and Crystal Structure of a New Modification of Tetraselenium Tetranitride, Se₄N₄ β-Se₄N₄ has been prepared by the reaction of selenium dioxide with the phosphane imine Me₃SiNPMe₃ in acetonitrile, forming red-brown crystal needles. The crystal structure analysis shows a new modification, the IR spectrum of which differs only slightly from the known α-form of Se₄N₄ (space group C2/c). β-Se₄N₄: Space group P2₁/n, Z = 4, structure solution with 1 667 observed unique reflections, R = 0.054. Lattice dimensions at ?50°C: a = 881.8(2), b = 738.7(2), c = 899.6(2) pm, β = 93.58(1)°. Just as the α-form β-Se₄N₄ forms cage molecules without symmetry and intramolecular Se? Se contacts of 273.2 and 274.0 pm. There are strong Se…?N-interactions between the Se₄N₄ molecules.     

Polyselenide mit langkettigen Tetraalkylammoniumionen Die Kristallstruktur von Trimethyl-tetradecyl-ammonium-hexaselenid

Polyselenides with Long-chain Tetraalkylammonium Ions. Crystal Structure of Trimethyltetradecyl-ammonium Hexaselenide Na₂Se₂ and Na₂Se react with various tetraalkylammonium halides in ethanol and in presence of grey selenium and catalytic quantities of iodine forming different polyselenides Se_n^2? (n = 3, 5—9). In the solutions equilibria of polyselenides seem to occur; cooling of saturated solutions causes crystallization of polyselenides with a composition depending on the cation. Tri- and pentaselenide are dark green. The higher members form black crystals, all compounds are sensitive to oxygen. The i.r. spectra are reported. [(CH₃)₃N(CH₂)₁₃CH₃]₂Se₆ is characterized by a crystallographic structure determination with X-ray data: space group P2₁2₁2, Z = 4, a = 5043, b = 734.2, c = 600.3 pm (986 observed independent reflexions. R = 0.072). The compound consists of trimethyl tetradecylammonium ions and angular Se₆^2? chains of symmetry C₂ with Se? Se bond lengths of 227 and 235 pm.     

Ternäre Halogenide vom Typ A3MX6. III [1, 2]. Synthese,Strukturen und Ionenleitfähigkeit der Halogenide Na3MX6 (X = Cl,Br)

Ternary Halides of the A₃MX₆ Type. III [1, 2]. Synthesis, Structures, and Ionic Conductivity of the Halides Na₃MX₆ (X = Cl, Br) The bromides Na₃MBr₆ crystallize with the stuffed LiSbF₆-type structure (type I; M = Sm? Gd) or with the structure of the mineral cryolite (type II; M = Gd? Lu). The structure types were refined from single crystal X-ray data (Na₃SmBr₆: trigonal, space group R3 , a = 740.8(2) pm, c = 1 998.9(8) pm, Z = 3; Na₃YBr₆: monoclinic, space group P2₁/n, a = 721.3(4) pm, b = 769.9(2) pm, c = 1 074.8(4) pm, β = 90.60(4)°, Z = 2). Reversible phase transitions from one structure to the other occur. The phase transition temperatures were determined for the bromides as well as for the chlorides Na₃MCl₆ (M = Eu? Lu). The refinement of both structures for one compound was possible for Na₃GdBr₆ (I: trigonal, space group R3 , a = 737.1(5) pm, c = 1 887(2) pm, Z = 3; II: monoclinic, space group P2₁/n, a = 725.2(1) pm, b = 774.1(3) pm, c = 1 080.1(3) pm, β = 90.76(3)°, Z = 2). All compounds exhibit ionic conductivity of the sodium ions which decreases with the change from type I to type II. The conductivity of the bromides is always higher when compared with the respective chlorides.     

Darstellung und Kristallstruktur von SnTl4Se3 mit einer Anmerkung zu TlSe

Preparation and Crystal Structure of SnTl₄Se₃ with a Note on TlSe We describe the preparation and crystal structure of SnTl₄Se₃. It crystallizes as a low symmetric distorted derivative with the In₅Bi₃ type of structure, which itself should be considered as a subfamily of the Cr₅B₃ type of structure: a = 852.2(2) pm, c = 1 272.2(6) pm, c/a = 1.49, Z = 4. Short Sn? Se distances of 311 pm, and 326 pm, respectively, are obtained in [SnSe_2/2] chains running along [001]. Furthermore, short Tl? Se distances are found in quasimolecular bent moieties Tl₂Se: 300 pm, 313 pm, and 347 pm, respectively. SnTl₄Se₃ is a semiconductor. The conductivity of some closely related phases are also reported. Finally, the structure of the well known compound TlSe has been refined for the first time, in order to get some more information about Tl¹⁺? Se distances for square-antiprismatic coordinated Tl¹⁺ ions.     

[Ga(en)3][Ga3Se7(en)] · H2O: Ein Galliumchalkogenid mit Ketten aus [Ga3Se6Se2/2(en)]3–-Bicyclen

[Ga(en)₃][Ga₃Se₇(en)] · H₂O: A Gallium Chalcogenide with Chains of [Ga₃Se₆Se_2/2(en)]^3– Bicycles The new selenidogallate [Ga(en)₃][Ga₃Se₇(en)] · H₂O ( I ) was produced from a ethylendiamine suspension of Ga and Se at 130 °C. I crystallizes in the orthorhombic space group Pna2₁ with unit constants a = 1347.9(3) pm, b = 961.6(1) pm, c = 1967.6(4) pm and Z = 4. The crystal structure contains an anion so far not observed in gallium chalcogenides. It is built from [Ga₃Se₆Se_2/2(en)]^3– bicycles of three Ga^IIIL₄ tetrahedra (L = en, Se) connected via selenium corners to linear chains. The cations, Ga^III ions coordinated by three ethylendiamine in a distorted octahedral geometry are positioned in the holes of the hexagonal rod packing of these chains.     

Divalent Samarium: Synthesis and Crystal Structures of Sm4OCl6 and KSm2Cl5

Single crystals of Sm₄OCl₆ and KSm₂Cl₅ have been obtained by metallothermic reductions of SmCl₃ with lithium (in the presence of Sm₂O₃ or SmOCl) and potassium, respectively, at elevated temperatures in sealed tantalum containers. Sm₄OCl₆ (hexagonal, P6₃mc, Z = 2, a = 946.59(4), c = 717.88(4) pm) and KSm₂Cl₅ (monoclinic, P2₁/c, Z = 4, a = 888.06(6), b = 784.81(5), c = 1262.77(8) pm, ß = 90.085(6)°) are true divalent samarium compounds, Sm₄OCl₆ with remarkably short Sm²⁺–O^2? distances (236.0, 237.6 (3x) pm) within the [Sm₄O] tetrahedron.