Rb4Zr3Te16, a one‐dimensional ­zirconium telluride synthesized from molten salt

A new ternary metal telluride, tetra­rubidium tri­zircon­ium hexa­deca­telluride, Rb₄Zr₃Te₁₆, has been synthesized through reactions at 698 K using elemental Zr and an Rb₂Te/Te melt as a reactive flux, and characterized by single‐crystal X‐ray diffraction. Although the structure of this compound is very similar to its Cs₄Zr₃Te₁₆ analogue, the compounds crystallize in different space groups, the former in C_2h⁶ –C2/c and the latter in C_2h⁵ –P2₁/n. Both compounds consist of infinite one‐dimensional chains of [Zr₃Te₁₆]_n^4n? separated from each other by Rb⁺ or Cs⁺ cations. Within the chain, each Zr atom is surrounded by eight Te atoms to give a distorted bicapped trigonal prism polyhedron. There are two unambiguous Te—Te single bonds of 2.758 (2) and 2.765 (2) Å, and four longer Te?Te interatomic distances in the range of 2.9277 (14)–3.0445 (18) Å that indicate weak interactions between the adjacent Te atoms. Because of the wide range of Te?Te interactions, simple formalisms cannot be used to describe the bonding within the chain.     

Synthesis and Crystal Structure of Manganese‐tris(1,2‐ethanediamine)tetratelluride [Mn(en)3]Te4 Exhibiting Intermolecular Interactions between the Tetratelluride Anions

Air‐sensitive black crystals of the new compound [Mn(en)₃]Te₄ were synthesized by reacting MnCl₂ · 4 H₂O, K₂Te₃ and elemental Te in 1,2‐ethanediamine (en) under solvothermal conditions at 433 K. The compound crystallizes in the monoclinic space group P2₁/n with lattice parameters a = 839.51(7) pm, b = 1551.3(1) pm, c = 1432.6(1) pm, and β = 90.28(2)°. Isolated [Mn(en)₃]²⁺ cations and Te₄^2– anions are arranged in an alternating fashion parallel to the crystallographic b‐axis. One terminal Te atom of the Te₄^2– anions exhibits a short intermolecular contact to a neighboured anion thus forming Te₈^4– anions. A slightly longer interionic Te…Te separation is observed between two of the inner Te atoms of neighboured Te₈^4– anions. Taking these longer separations into account infinite Te‐chains are formed running parallel to [001]. The intermolecular Te…Te interactions affect the Te–Te bond lengths within the Te₄^2– anion leading to a lengthening of the average Te–Te distance. Short N–H…Te distances indicate hydrogen bonding between the cations and anions. DTA‐TG measurements show that at 441 K the material decomposes in one step. The resulting crystalline material consists of MnTe₂ and Te.     

[Te8]2[Ta4O4Cl16]: A Two‐dimensional Tellurium Polycation obtained via Ionic Liquid‐Based Synthesis

By reaction of elemental tellurium, tellurium(IV) chloride, tantalum(V) chloride and tantalum(V) oxychloride in the ionic liquid [BMIM]Cl ([BMIM]Cl:1‐Butyl‐3‐methylimidazolium chloride),[Te₈]₂[Ta₄O₄Cl₁₆] is obtained in the form of lucent black crystals. The title compound consists of infinite [Te–Te–(Te₆)]_n²⁺ chains (Te–Te: 264.9(1)–284.3(1) pm) and isolated [Ta₄O₄Cl₁₆]^4– anions. The [Te–Te–(Te₆)]_n²⁺ chains are interconnected to form a two‐dimensional tellurium network (Te–Te: 335.9 pm). Due to this interaction the [Te–Te–(Te₆)]_n²⁺ chains in [Te₈]₂[Ta₄O₄Cl₁₆] show an arrangement that differs significantly from known polycationic [Te₈]_n²⁺ chains. The two‐dimensional tellurium network is finally separated by tetrameric, corner‐sharing oxidochloridotantalate anions [(TaO_2/2Cl_4/1)₄]^4– that are firstly observed. The composition of [Te₈]₂[Ta₄O₄Cl₁₆] is confirmed by EDX analysis; its optical band gap is estimated to 1.1–1.2 eV via UV/Vis spectroscopy.     

[(Te2)3{Mn(CO)3}2{Mn(CO)4}3]– – A Novel Tellurium‐­Manganese Carbonyl with Ufosane‐like Structure

By reacting Mn₂(CO)₁₀ and TeI₄ in the ionic liquid[BMIm][OTf] (1‐butyl‐3‐methylimidazolium trifluromethanesulfonate), brick‐red crystals of [BMIm][(Te₂)₃{Mn(CO)₃}₂{Mn(CO)₄}₃]are obtained. The title compound contains the carbonyl anion[(Te₂)₃{Mn(CO)₃}₂{Mn(CO)₄}₃]^–. Herein, three formal Te₂^2– units and two formal Mn(CO)₃⁺ fragments establish a distorted heterocubane‐like Te₆Mn₂ structure. Three edges of this heterocubane are furthermore capped by Mn(CO)₄⁺ fragments. The resulting Te₆Mn₅ building unit, moreover, looks very similar to the P₁₁^3– anion – the so‐called ufosane. The mean distances Te–Te and Te–Mn are observed with 277.6 and 264.7 pm, respectively. In addition to single‐crystal structure analysis, the title compound is characterized by infrared spectroscopy (FT‐IR), thermogravimetry (TG) and energy‐dispersive X‐ray (EDX) analysis.     

Synthese und Kristallstruktur von Te3O3(PO4)2, einer Verbindung mit fünffach koordiniertem Tellur(IV)

Synthesis and Crystal Structure of Te₃O₃(PO₄)₂, a Compound with 5‐fold Coordinate Tellurium(IV) Polycrystalline Te₃O₃(PO₄)₂ is formed during controlled dehydration of (Te₂O₃)(HPO₄) with (Te₈O₁₀)(PO₄)₄ as an intermediate product. Colourless single crystals were prepared by heating stoichiometric amounts of the binary oxides P₂O₅ und TeO₂ in closed silica glass ampoules at 590 °C for 8 hours. The crystal structure (P2₁/c, Z = 4, α = 12.375(2), b = 7.317(1), c = 9.834(1)Å, β = 98.04(1)°, 1939 structure factors, 146 parameters, R[F² > 2σ(F²)] = 0.0187, wR2(F² all) = 0.0367) was determined from four‐circle diffractometer data and consists of [TeO₅] polyhedra und PO₄ tetrahedra as the main building units. The framework structure is made up of cationic zigzag‐chains of composition [Te₂O₃]²⁺ which extend parallel to [001] and anionic [Te(PO₄)₂]^2— units linked laterally to these chains. This leads to the formation of [Te₂O₃][Te(PO₄)₂] layers parallel to the bc plane which are interconnected via weak Te‐O bonds.     

A square‐planar tellurium(II) complex with Te,Te′‐chelating ligands

While exploring the chemistry of tellurium‐containing dichalcogenidoimidodiphosphinate ligands, the first all‐tellurium member of a series of related square‐planar E^II(E′)₄ complexes (E and E′ are group 16 elements), namely bis(P,P,P′,P′‐tetraphenylditelluridoimidodiphosphinato‐κ²Te,Te′)tellurium(II) (systematic name: 2,2,4,4,8,8,10,10‐octaphenyl‐1λ³,5,6λ⁴,7λ³,11‐pentatellura‐3,9‐diaza‐2λ⁵,4λ⁵,8λ⁵,10λ⁵‐tetraphosphaspiro[5.5]undeca‐1,3,7,9‐tetraene), C₄₈H₄₀N₂P₄Te₅, was obtained unexpectedly. The formally Te^II centre is situated on a crystallographic inversion centre and is Te,Te′‐chelated to two anionic [(TePPh₂)₂N]⁻ ligands in an anti conformation. The central Te^II(Te)₄ unit is approximately square planar [Te—Te—Te = 93.51 (3) and 86.49 (3)°], with Te—Te bond lengths of 2.9806 (6) and 2.9978 (9) Å.     

Acetonyl­di­chloro­[(Z)‐2‐chloro‐2‐phenyl­vinyl]­tellurium(IV), helical chains of metal complexes

The primary geometry about the Te^IV atom in the title compound, [TeCl₂(C₈H₆Cl)(C₃H₅O)] or C₁₁H₁₁Cl₃OTe, is a pseudo‐trigonal‐bipyramidal arrangement, with two Cl atoms in apical positions, and the lone pair of electrons and C atoms in the equatorial plane. The Te^IV atom is involved in three secondary interactions, two intramolecular [Te?O = 2.842 (3) Å and Te?Cl3 = 3.209 (1) Å] and one intermolecular [Te?Cl = 3.637 (1) Å], the latter giving rise to a helical chain. These helices are linked by C—H?O interchain interactions.     

Features of phase formation and state of iron in the quasibinary system FeTe1.65-TiTe1.65

A series of tellurides Fe_xTi_1?x Te_1.65 (x = 0, 0.1, 0.2 …, 1.0) synthesized at 850°C were studied by X-ray phase and X-ray fluorescent analysis and Møssbauer spectroscopy on ⁵⁷Fe. In this series two solid solutions are formed: phases I and II with homogeneity regions within the limits of 0 ≤ x ≤ 0.3 and 0.9 ≤ x ≤ 1.0, respectively. Iron in this series exists in two various states: Fe²⁺ _sym and Fe²⁺ _asym as differentiated from the series of tellurides Fe_xTi_1?x Te_1.45 where three states of iron Fe²⁺ _sym, Fe²⁺ _asym, and Fe⁰ were found. On passing from Fe_xTi_1?x Te_1.45 to Fe_xTi_1?x Te_1.65 the number of formed phases decreases, and phase relations become simpler. The absence of Fe⁰ from phase I of tellurides Fe_xTi_1?x Te_1.65 can point to the fact that TiTe_1.45 and TiTe_1.65 belong to different homogeneity regions.     

Resonanzramanspektrum und Struktur von matrixisoliertem Te3

Resonance Raman Spectrum and Structure of Matrixisolated Te₃ By condensing a mixture of 76% Te atoms and 24% Te₂ molecules in a nitrogen matrix at 15 K followed by annealing to nearly 25 K we obtained Te₃ molecules by a matrix reaction. The resonance Raman spectrum of Te₃ contains 8 overtones of the symmetric stretching vibration. The following values for ω₁ and x₁₁ have been calculated for the isotopically pure species ¹²⁶Te₃: ω₁ = 206.33 ± 0.15 cm^?1; x₁₁ = 0.24 ± 0.03 cm^?1 and ¹³⁰Te₃: ω₁ = 203.1 ± 0.2 cm^?1; x₁₁ = 0.22 ± 0.05 cm^?1. Using a 1:1 ratio of ¹²⁶Te and ¹³⁰Te in the synthesis of Te₃ the band shape of the envelopes of the superimposed spectra of all possible Te₃ species could only be explained assuming a bent structure (120° ± 10°). The value of the force constant f_r + f_rr of 210 ± 10 Nm^?1 reflects multiple bonding in this molecule. The proposed structure also agrees with thermodynamical considerations.     

Two new phosphate langbeinites,Rb2YbTi(PO4)3 and Rb2Yb0.32Ti1.68(PO4)3, investigated at 293 and 150 K

The rubidium ytterbium titanium phosphates Rb₂YbTi(PO₄)₃, (I), and Rb₂Yb_0.32Ti_1.68(PO₄)₃, (II), have been structurally characterized from X‐ray data collected at both 293 and 150 K. Compound (II) is blue owing to the presence of mixed‐valence titanium (41% Ti³⁺ + 59% Ti⁴⁺). Both (I) and (II) belong to the langbeinite structure type, with mixed Yb/Ti populations in the two crystallographically independent octahedral sites (of symmetry 3). Ytterbium favours one of these sites, where about two‐thirds of the Yb atoms are found. The O‐atom displacement parameters are large in both compounds at both temperatures.     

A New Strategy for Realizing the Conversion of “Homo–Hetero–Homo” Heteroepitaxial Growth in Bi2Te3 and the Thermoelectric Performance

Uncovering the reason for structure‐dependent thermoelectric performance still remains a big challenge. A low‐temperature and easily scalable strategy for synthesizing Bi₂Te₃ nanostring hierarchical structures through solution‐phase reactions, during which there is the conversion of “homo–hetero–homo” in Bi₂Te₃ heteroepitaxial growth, is reported. Bi₂Te₃ nanostrings are obtained through the transformation from pure Bi₂Te₃ hexagonal nanosheets followed by Te?Bi₂Te₃ “nanotop” heterostructures to Bi₂Te₃ nanostrings. The growth of Bi₂Te₃ nanostrings appears to be a self‐assembly process through a wavy competition process generated from Te and Bi³⁺. The conversion of homo–hetero–homo opens up new platforms to investigate the wet chemistry of Bi₂Te₃ nanomaterials. Furthermore, to study the effect of morphologies and hetero/homo structures, especially with the same origin and uniform conditions on their thermoelectric properties, the thermoelectric properties of Bi₂Te₃ nanostrings and Te?Bi₂Te₃ heterostructured pellets fabricated by spark plasma sintering have been investigated separately.     

Rb3Y2(BO3)3 with a noncentrosymmetric structure

Trirubidium diyttrium triborate contains zigzag chains of corner‐sharing [Y₂O₁₀] dimers. The chains are reinforced by one independent BO₃ group and crosslinked by the other two types of BO₃ groups to form a three‐dimensional framework. Channels along the [100] direction accommodate the Rb⁺ cations.     

[Hg8(μ‐n‐C3H7Te)12(μ‐Br)Br3] — Synthesis and Structure

The novel mercury‐tellurium cluster [Hg₈(μ‐n‐C₃H₇Te)₁₂(μ₂‐Br)Br₃] is formed during the reaction of HgBr₂ and (n‐C₃H₇Te)₂Hg in DMSO. Its crystal structure has been elucidated showing [Hg₈(μ‐n‐C₃H₇Te)₁₂(μ₂‐Br)]³⁺ units with a bromine‐centered distorted Hg₈ cube. The mercury atoms are bridged by n‐C₃H₇Te^— ligands and the resulting clusters are linked to a three‐dimensional network by bromine atoms. The close packing of the cluster is mainly determined by the flexible n‐propyl residues of the telluride building blocks.     

A high‐pressure single‐crystal synchrotron diffraction study of NH4RbTe4O9·2H2O: stability of three different TeOx coordination polyhedra

The crystal structure of ammonium rubidium nonaoxotetratellurate(IV) dihydrate has been studied as a function of pressure up to 7.40 GPa. The ambient‐pressure structure is characterized by the co‐existence of three different Te—O polyhedra (TeO₃, TeO₄ and TeO₅), which are connected to form layers. NH₄⁺, H₂O and Rb⁺ are incorporated between the layers. Both the Rb1 position, which is located on a twofold axis, and the Rb2 position are partially occupied. The three different types of coordination polyhedra around Te⁴⁺ are stable up to at least 5.05 GPa. No phase transition is observed. The fit of the unit‐cell volume as a function of pressure gives a zero‐pressure bulk modulus of 34 (1) GPa with a zero‐pressure volume of V₀ = 2620 (4) ų [B′ = 1.4 (2)].     

[Te8][NbOCl4]2 containing an infinite chain‐like {[Te–Te–Te–(Te5)]2+}n polycation

The title compound, [Te₈][NbOCl₄]₂, was obtained as translucent black crystals by reaction of elemental tellurium, niobium(V) chloride and niobium(V) oxychloride in the ionic liquid BMImCl (BMImCl is 1‐butyl‐3‐methylimidazolium chloride). The synthesis was performed in argon‐filled glass ampoules. According to X‐ray structure analysis based on single crystals, the title compound crystallizes with triclinic lattice symmetry and consists of infinite {[Te₈]²⁺}_n cations associated with pyramidal [NbOCl₄]⁻ anions. The novel catena‐octatellurium(2+) cation is composed of Te₅ rings that are linked via Te₃ units [Te—Te = 2.6455 (18)–2.8164 (19) Å]. The composition and purity of [Te₈][NbOCl₄]₂ were further confirmed by energy‐dispersive X‐ray diffraction (EDX) analysis.     

Synthesis and Crystal Structure of α‐ThTe3

The binary thorium tritelluride, α‐ThTe₃, was synthesized by solid‐state methods at 1223 K. From a single‐crystal X‐ray diffraction study the material crystallizes in the TiS₃ structure type with two formula units in space group C²_2h–P2₁/m of the monoclinic system in a cell with lattice constants a = 6.1730 (4) Å, b = 4.3625(3) Å, c = 10.4161(6) Å, and β = 97.756(3)° (at 100 K). The asymmetric unit of this compound comprises one Th atom and three Te atoms each with site symmetry m. Each Th atom is coordinated to eight Te atoms in a bicapped trigonal‐pyramidal arrangement. Th–Te distances range from 3.1708(4) Å to 3.2496(6) Å. The structure features a Te–Te interaction 2.7631(8) Å in length, which is typical for a Te–Te single bond. Thus α‐ThTe₃ may be charge balanced and formulated as Th⁴⁺Te^2–Te₂^2–.     

Syntheses,Crystal Structures,and Properties of New Ternary Chalcogenides of Group 4 Metals: Rb4Ti3S14, Cs4Zr3S14, K4Hf3Se14, and K4ZrHf2Se14

The new ternary compounds Rb₄Ti₃S₁₄, Cs₄Zr₃S₁₄, K₄Hf₃Se₁₄, and K₄ZrHf₂Se₁₄ were prepared by reacting the respective transition metals in alkali metal polychalcogenide melts. Two crystallographically independent transition metal cations are present that are coordinated by eight chalcogen atoms (Q) in an irregular fashion or by seven chalcogen atoms yielding a distorted pentagonal bipyramid. The M(1)Q₈ and M(2)Q₇ polyhedra are connected by sharing common edges or trigonal faces leading to the formation of infinite linear one‐dimensional anionic chains running parallel to the [101] direction. The chains are separated by alkali metal cations. The optical band gaps determined are 1.59 eV for Rb₄Ti₃S₁₄, 2.35 eV for Cs₄Zr₃S₁₄, and 2.02 eV for K₄Hf₃Se₁₄. In‐situ X‐ray powder diffractometry demonstrates that Rb₄Ti₃S₁₄ decomposes at 430 °C into Rb₂S₅ and TiS. During the cooling cycle the re‐formation of the polysulfide is observed. According to this result the polysulfide could be prepared using TiS instead of metallic Ti as well.     

Die Kristallstruktur von KPr3Te8

Crystal Structure of KPr₃Te₈ Out of the compounds ALn₃Q₄ (A = Na, K, Rb, Cs; Ln = Lanthanoid; Q = S, Se and Te) the crystal structure of the telluride KPr₃Te₈ was determined by X‐ray single‐crystal structure analysis. Single crystals of the compound were synthesized by a flux technique with K₂Te₃ as flux after separation of the K₂Te₃ excess by extraction with absolute dimethylformamide (DMF). The compound crystallizes monoclinically in space group P12₁/c1 with the lattice parameters a = 1390.58(7) pm, b = 1291.06(6) pm, c = 900, 18(5) pm and β = 99, 264(6)° isotypically to KNd₃Te₈. Characteristics in the crystal structure of KPr₃Te₈ are L‐shaped units of three tellurium atoms [Te₃]^2— as well as infinite zig‐zag chains of tellurium atoms [Te₄]^4—. The shortest interatomic distances in the chain are alternating only slightly with 298 and 300 pm and are in the range of partial bonds. Both structure elements are arranged in almost planar layers and are interconnected with each other by secondary interactions revealing interatomic distances in the range of 327 to 349 pm. The crystal structure of KPr₃Te₈ can be regarded as a addition‐defect variant of the binary NdTe₃ structure type. This finding is illustrated by group‐subgroup relations in form of a so called Bärnighausen family tree.     

Neutral tellurium rings in the coordination polymers [Ru(Te9)](InCl4)2, [Ru(Te8)]Cl2, and [Rh(Te6)]Cl3

Shiny black, air‐insensitive crystals of tellurium‐rich one‐dimensional coordination polymers were synthesized by melting a mixture of the elements with TeCl₄. The compounds [Ru(Te₉)](InCl₄)₂ and [Ru(Te₈)]Cl₂ crystallize in the monoclinic space group type C2/c, whereas [Rh(Te₆)]Cl₃ adopts the trigonal space group type R$\bar 3Shiny black, air-insensitive crystals of tellurium-rich one-dimensional coordination polymers were synthesized by melting a mixture of the elements with TeCl(4). The compounds [Ru(Te(9))](InCl(4))(2) and [Ru(Te(8))]Cl(2) crystallize in the monoclinic space group type C2/c, whereas [Rh(Te(6))]Cl(3) adopts the trigonal space group type R ?3c. In the crystal structures, linear, positively charged [M(m+) (Te(n)(±0))] (M=Ru, m=2; Rh, m=3) chains run parallel to the c axes. Each of the uncharged Te(n) molecules (n=6, 8, 9) coordinates two transition-metal atoms as a bridging bis-tridentate ligand. Because the coordinating tellurium atoms act as electron-pair donors, the 18-electron rule is fulfilled for the octahedrally coordinated transition-metal cations. Based on DFT calculations, the quantum theory of atoms in molecules (QTAIM) and the electron localizability indicator (ELI) provide insight into the principles of the polar donor bonding in these complexes. Comparison with optimized ring geometries reveals substantial tension in the coordinating tellurium molecules.     

Molecular building blocks for solid‐state chalcogenides: solvothermal synthesis of [Mn(en)3]Te4 and [Fe(en)3]2(Sb2Se5)

Two new molecular metal chalcogenides, tris­(ethyl­enedi­amine‐N,N′)­manganese(II) tetratelluride, [Mn(C₂H₈N₂)₃]Te₄, (I), and bis­[tris­(ethyl­enedi­amine‐N,N′)­iron(II)] penta­seleno­diantimonate(III), [Fe(C₂H₈N₂)₃]₂(Sb₂Se₅), (II), containing the isolated molecular building blocks Te₄^2? and Sb₂Se₅^4?, have been synthesized by solvothermal reactions in an ethyl­enedi­amine solution at 433 K. The anion Te₄^2? in (I) is a zigzag oligometric chain with Te—Te bond lengths in the range 2.709–2.751 Å. There is a very short contact [3.329 (1) Å] between a pair of neighboring Te₄^2? anions. In (II), each Sb atom is surrounded by three Se atoms to give a tripodal coordination. One of the three independent Se atoms is a μ₂‐bridging ligand between two Sb atoms; the other two are terminal.