Ba6(MN4)N2–x (M = MoVI/TaV), a Subvalent Nitridometalate with Perovskite‐like Crystal Structure

The subvalent nitridometalate Ba₆[(Mo_1–xTa_x)N₄]N_0.86 was prepared from mixtures of Mo powder with Ba, Na, and Ba₂N at 600 °C in Ta ampoules. It crystallizes in space group Cmcm with a = 11.672(3), b = 10.177(2) and c = 10.8729(19) Å. Its crystal structure exhibits an orthorhombically distorted Perovskite topology with [Ba₆N] building units forming the ReO₃‐type lattice via common vertices, and the nitridometalate anions occupying half of the available distorted cuboctahedral interstices. [MN₄] anions show statistically mixed occupancy of M by Mo^VI and Ta^V. They show no notable deviation from nitridometalate anions in known ionic nitridomolybdates and ‐tantalates, and the metrics of the [Ba₆N] octahedra correspond to those found in similar subvalent compounds. The nitrogen atom position centering the [Ba₆N] octahedra is underoccupied. Band structure calculations corroborate the subvalent character of the compound and the two individual anionic structural building units.     

Tantalcluster in oxidischer Matrix – Synthese und Strukturen der gemischtvalenten Oxotantalate M2–δTa15O32 (M = K,Rb (δ = 0); M = Sr (δ = 0.15), Ba (δ = 0.12))

Tantalum Cluster in an Oxidic Matrix – Synthesis and Structures of Mixed-Valence Oxotantalates M_2–δTa₁₅O₃₂ (M = K, Rb (δ = 0); M = Sr (δ = 0.15), Ba (δ = 0.12)) The mixed-valent oxides Sr_1.85Ta₁₅O₃₂ ( 1 ), Ba_1.88Ta₁₅O₃₂ ( 2 ), K₂Ta₁₅O₃₂ ( 3 ), Rb₂Ta₁₅O₃₂ ( 4 ) were prepared from appropriate mixtures of Ta₂O₅, tantalum and the corresponding carbonate at 1520–1670 K in sealed tantalum tubes. According to X-ray single crystal structure analyses the oxides crystallize in the space group R3¯, Z = 1. The lattice parameters in the hexagonal setting are a = 777.36(11), c = 3516.2(7) pm for 1 , a = 778.87(11), c = 3548.1(7) pm for 2 , a = 780.7(2), c = 3573.1(11) pm for 3 , and a = 781.90(11), c = 3593.0(7) pm for 4 . The oxide ions form a defect dense packing with the layer sequence chhhh. Anti-cuboctahedral sites are completely occupied by the alkali metal cations. The alkaline earth cations occupy 92 to 94% of such sites; they are displaced from the centres. Smaller voids are located in the centres of the cuboctahedral Ta₆O₁₂ clusters forming the characteristic structural unit of these low-valent oxotantalates. In case of 3 and 4 the clusters have 13 electrons, in case of 1 and 2 they have close to 15 electrons available for Ta–Ta-bonding. Moreover, the structures of the alkali and alkaline earth metal compounds differ notably with respect to the spectrum of Ta–O and Ta–Ta distances in the Ta₃O₁₃ octahedra triples forming another characteristic structural unit for these oxides. Such differences are traced back to distinct local charge balances for the uni- and divalent cations. The oxides 2 , 3 are semiconductors with band gaps ranging from 130 to 360 meV.     

Kristallzucht und Strukturverfeinerung von Quecksilber(II)‐amidchlorid – HgClNH2

Crystal Growth and Refinement of the Crystal Structure of Mercury(II) Amide Chloride – HgClNH₂ Single crystals were prepared by recrystallization of HgClNH₂ from aqueous NH₃/NH₄⁺ solution at 160 °C. They were used for a single‐crystal X‐ray structure redetermination. The previously reported [W. N. Lipscomb, Acta. Crystallogr. 1951 , 4, 266.] structural topology determined on basis of X‐ray powder diffraction data is now confirmed. However, a higher symmetry is found: Space group type Pmma (instead of Pmm2), a = 6.709(1) Å, b = 4.351(1) Å, c = 5.154(1) Å, Z = 2. The crystal structure contains zig‐zag‐chains [Hg(NH₂)_2/2]⁺. Four Cl atoms complete the coordination sphere of Hg to a distorted octahedron. These share common faces and edges in layers [HgCl_4/4(NH₂)_2/2]. These layers are connected via hydrogen bonds N–H…Cl.     

Synthesis and Crystal Structure of Rb6Ta4S22: The First Tantalum Polysulfide Composed of the Dimeric Complex Anion [Ta4S22]6–

The reaction of Rb₂S₃, Ta and S in a 1.3 : 1 : 5.6 molar ratio at 400 °C yields red‐orange crystals of the new ternary compound Rb₆Ta₄S₂₂ being the first tantalum polysulfide containing the dimeric complex anion [Ta₄S₂₂]^6–. The polysulfide anions are composed of two Ta₂S₁₁ subunits which are linked to Ta₄S₂₂ units via terminal sulfur ligands. The Ta⁵⁺ centers are coordinated by S₂^2– and S^2– ligands according to [(Ta₂(μ₂‐η²,η¹‐S₂)₃(η²‐S₂)(S)₂)₂(μ₂‐η¹,η¹‐S₂)]^6–. Every Ta⁵⁺ ion is surrounded by seven sulfur ions forming a strongly distorted pentagonal bipyramid. In the crystal structure the discrete [Ta₄S₂₂]^6– anions are stacked parallel to the crystallographic b‐axis. The Rb⁺ cations are located between these stacks. Rb₆Ta₄S₂₂ crystallizes in the monoclinic space group P2₁/c (No. 14) with a = 11.8253(9) Å, b = 7.9665(4) Å, c = 19.174(2) Å, β = 104.215(9)°, V = 1751.0(2) ų, Z = 2.     

Rubidium‐ und Caesium‐Verbindungen mit dem Isopolyanion [Ta6O19]8– – Synthesen,Kristallstrukturen, thermische und schwingungsspektroskopische Untersuchungen der Oxotantalate A8[Ta6O19] · n H2O (A = Rb,Cs; n = 0, 4, 14)

Rubidium und Caesium Compounds with the Isopolyanion [Ta₆O₁₉]^8– – Synthesis, Crystal Structures, Thermogravimetric and Vibrational Spectrocopic Analysis of the Oxotantalates A₈[Ta₆O₁₉] · n H₂O (A = Rb, Cs; n = 0, 4, 14) The compounds A₈[Ta₆O₁₉] · n H₂O (A = Rb, Cs; n = 0, 4, 14) contain the isopoly anion [Ta₆O₁₉]^8–, which consists of six [TaO₆] octahedra connected via corners to form a large octahedron. They transform into each other by reversible hydratation/dehydratation processes, as shown from thermoanalytic measurements (TG/DSC), and show also structural similarities. Cs₈[Ta₆O₁₉] (tetragonal, I4/m, a = 985.9(1) pm, c = 1403.3(1) pm, Z = 2), the isotypic phases A₈[Ta₆O₁₉] · 14 H₂O (A = Rb/Cs; monoclinic, P2₁/n, a = 1031.30(6)/1055.4(1) pm, b = 1590.72(9)/1614.9(6) pm, c = 1150.43(6)/1171.4(1) pm, β = 100.060(1)/99.97(2)°, Z = 2) and Rb₈[Ta₆O₁₉] · 4 H₂O (monoclinic, C2/c, a = 1216.9(4) pm, b = 1459.2(5) pm, c = 1414.7(4) pm, β = 90.734(6)°, Z = 4) have been characterised on the basis of single crystal x‐ray data. Furthermore the RAMAN spectra allow a detailled comparison of the hexatantalate ions in the four compounds.     

Die metallreiche Schichtstruktur von Ta6STe3

The Metal‐rich Layer Structure of Ta₆STe₃ Ta₆S_1+xTe_3–x was prepared from an appropriate mixture of 2 H–Ta_1.3S₂, TaTe₂, and Ta in a fused tantalum tube at 1273 K within 3 d. The results of a X‐ray single crystal structure analysis for a phase near the Te‐rich limit of the homogeneity range are reported. Ta₆S_1.00Te_3.00(1) crystallizes in the triclinic space group P1, a = 993.14(8) pm, b = 1032.18(8) pm, c = 1378.78(11) pm, α = 79.32(1)°, β = 81.36(1)°, γ = 85.74(1)°, Z = 6, Pearson symbol aP60, 6048 I_o > 2σ (I_o), 286 variables, wR₂ = 0.067. The metal‐rich layer structure of Ta₆STe₃ comprises distorted icosahedral Ta₁₃ clusters and related deltahedral cluster fragments complemented by chalcogen atoms. The centred clusters consist of 11, 12, 13, 14, or 16 atoms. They interpenetrate into lamellae in which the tantalum and chalcogen atoms are spatially segregated according to [Q–Ta₃–Q]. The signature of the structure is a lenticular heptagonal antiprismatic Ta₃₀ cluster which seems to be excised from the pentagonal antiprismatic columnar structure of Ta₆S. The Ta₃₀ clusters and distorted icosahedral Ta₁₃ clusters are connected and fused into puckered layers. The rest of the tantalum valences are used for heteronuclear bonding. The chalcogen atoms having three to six next tantalum atoms coat the corrugated, tetrahedrally close‐packed layers. Ta₆STe₃ is a moderate metallic conductor (ρ_{293 K} = 3 × 10^–4 Ωcm) exhibiting typical temperature independent paramagnetic properties.     

On Polychalcogenides of Thallium with M2 Q11 Groups as a Structural Building Block. II. Tl4Ta2Se11: Synthesis,Crystal Structure,Properties and Spectroscopic Investigations of the First Polyselenide being Composed of a Discrete [Ta2Se11]4— Anion

The new ternary compound Tl₄Ta₂Se₁₁ was prepared in a melt of thallium polyselenides applying elemental tantalum. It crystallises in the triclinic space group P1¯ with a = 7.996(1) Å, b = 9.866(1) Å, c = 13.668(2) Å, α = 73.03(1)°, β = 89.21(2)° and γ = 85.72(1)°. Tl₄Ta₂Se₁₁ is the first polyselenide with discrete complex [M₂Se₁₁]^4— anions. Every Ta atom is in a sevenfold environment of Se atoms to form a distorted pentagonal bi‐pyramid. The two TaSe₇ polyhedra have a face in common thus yielding the [Ta₂Se₁₁]^4— unit. In the structure, the anions are well separated by the Tl¹⁺ cations. An assignment of the different vibration modes in the IR and Raman spectra is given based on density functional calculations.     

ZrIV‐ und TaV‐Komplexe mit methanoverbrückten Bis(aryloxy)‐Liganden

Zr^IV and Ta^V Complexes with Methano‐Bridged Bis(aryloxy) Ligands The bis(aryloxy) ligand precursor compounds bis(2‐trimethylsiloxy‐5‐tbutylphenyl)methane (L–SiMe₃) and its bromoderivative (2‐trimethylsiloxy‐3‐bromo‐5‐tbutylphenyl)(2′‐trimethylsiloxy‐5′‐tbutylphenyl)methane (L^Br–SiMe₃) are prepared in analogy to the corresponding calixarenes in excellent yields. X‐ray structure analysis for L^Br–SiMe₃: space group P2₁/c, a = 12.462(7), b = 10.466(6), c = 23.315(14) Å, β = 105.02(4)°, V = 2937(3) ų, Z = 4. L–SiMe₃ and L^Br–SiMe₃ react with Zr^IV and Ta^V chlorides in very good yields forming di‐ and trinuclear complexes. From the reaction of CpZrCl₃ with L^Br–SiMe₃ in the ratio of 3 : 2 a Zr₃ complex ( 7 ) is obtained, with one L^Br ligand only, which Zr atoms are bridged by a μ₃‐oxygen. The X‐ray structure analysis of 7 (space group R 3, a = 33.23(6), c = 24.47(8) Å, V = 23405(128) ų, Z = 18) additionally reveals that one phenolato oxygen atom of the L^Br ligand is terminally bound to a distorted tetragonal‐pyramidal coordinated Zr atom, while the second phenolato oxygen atom of the L^Br ligand forms a bridge to another Zr atom with a distorted octahedral coordination. The third Zr atom is also found in a distorted octahedral coordination mode. The reactions of L–SiMe₃ and L^Br–SiMe₃ with CpTaCl₄ and TaCl₅ yield dinuclear Ta complexes with a bridging bis(aryloxy) ligand. NMR spectroscopic data point out that the coordination of the bis(aryloxy) ligands in the Ta complexes very much resembles that in the Zr₃‐complex with one terminal and one bridging phenolato oxygen atom. The Zr₃ and the Ta complexes L^BrTa₂Cp₂Cl₆ and LTa₂Cl₈ were tested with respect to their catalytic properties in olefin polymerisation reactions in the presence of MAO.     

A mixed‐valent niobium oxy­sulfide,La2Nb3S2O8

Dilanthanum triniobium di­sulfide octaoxide, La₂Nb₃S₂O₈, crystallizes in the orthorhombic space group Pnnm and is isostructural with the Ln₂Ta₃X₂O₈ (Ln = La, Ce, Pr and Nd, and X = S and Se) family of tantalum compounds. Nb⁴⁺ and Nb⁵⁺ ions co‐exist in the structure and occupy different crystallographic sites. While the Nb⁴⁺ ions are found in mixed oxy­gen and sulfur octahedra, the Nb⁵⁺ ions are found in oxy­gen‐only octahedra.     

SrSn3 – eine supraleitende Legierung mit freien Elektronenpaaren

SrSn₃ – a Superconducting Alloy with Non‐bonding Electron Pairs SrSn₃ was synthesized from the elements in a welded niobium ampoule. The crystal structure was determined from X‐ray single crystal data. Space group R3m, a = 6,940(2) Å, c = 33,01(1) Å, Z = 12, Pearson symbol hR48. SrSn₃ shows an ordered atomic distribution on four crystallographic sites. The structure is build up from two closed packed atom layers (Sn1/Sr1 and Sn2/Sr2) each with the composition Sr : Sn = 1 : 3 and with hexagonal symmetry of the Sr atoms. The Sn atoms are shifted with respect to the ideal positions of a closed packed layer in a way that Sn triangles, which are separated by Sr atoms, result. Translational symmetry along the c axis arises from a 12‐layer stacking sequence with hexagonal and cubic closest packing motives. Due to the layer sequence ABABCACABCBC… units of three face‐sharing Sn octahedra result (condensation through Sn2 atoms) which form the Sn partial structure. The octahedra chains run parallel to the c axis and are connected by exclusively vertex sharing Sn octahedra (Sn1 atoms). Temperature dependent susceptibility measurements reveal superconducting properties. LMTO band structure calculations verify the metallic behavior. An analysis of the density of states with the help of the electron localization function (ELF) shows, that two kinds of lone pairs occur in this intermetallic phase: non‐bonding electron pairs with the shape of a sp² orbital hybrid are located at the Sn2 atoms and lone pairs with p orbital character are located at Sn1 atoms. The role of lone pairs with respect to the superconducting property is discussed.     

Hydrothermal Syntheses,Crystal Structures,and Luminescent Properties of Three Organic‐Lanthanide Complexes with 3‐Hydroxycinnamic Acid

Three new homodinuclear lanthanide(III) complexes [Ln₂(L)₆(2,2′‐bipy)₂] [Ln = Tb^III ( 1 ), Sm^III ( 2 ), Eu^III ( 3 ); HL = 3‐hydroxycinnamic acid (3‐HCA); 2,2′‐bipy = 2,2′‐bipyridine] were synthesized and characterized by IR spectroscopy, elemental analyses, and X‐ray diffraction techniques. Complexes 1 – 3 crystallize in triclinic system, space group P$\bar{1}$ . In all complexes the lanthanide ions are nine‐coordinate by two nitrogen atoms from the 2,2′‐bipy ligand and seven oxygen atoms from one chelating L ligands and four bridging L ligands, forming distorted tricapped trigonal prismatic arrangements. The lanthanide(III) ions are intramolecularly bridged by eight carboxylate oxygen atoms forming dimeric complexes with Ln ··· Ln distances of 3.92747(15), 3.9664(6), and 3.9415(4) Å for complexes 1 – 3 , respectively. The luminescent properties in the solid state of HL ligand and Eu^III complex are also discussed.     

Crystal Structures of NbOI3 and NbOBr3 – Polar Double Chains in Different Non‐centrosymmetric Structures

NbOI₃ was obtained from a reaction of Nb₂O₅, Nb, and I₂. Single crystals free from disorder were a by‐product from a reaction with additional CsI. The monoclinic crystal structure (C2, a = 14.624(3) Å, b = 3.9905(8) Å, c = 12.602(3) Å, β = 120.4(3)°, Z = 4, R₁(F) = 0.0368, wR₂(F²) = 0.0804) represents a new structure type which is built up by distorted octahedral NbI₄O₂ with unequal O‐atoms in trans‐position. The octahedra are linked to dimers by a common edge of iodine atoms and to double chains by the apical oxygen atoms. A non‐centrosymmetric structure results because the short Nb–O distances point to the same direction and the polar double chains are parallel. The crystal structure of NbOBr₃ (NbOCl₃‐type, , a = 11.635(6) Å, c = 3.953(2) Å, R₁(F) = 0.082, wR₂(F²) = 0.174) shows the same polar double chains but the dimeric units Nb₂Br₆O₂ are orthogonal.     

Ce2Ti2SiO9 – das erste Titanat‐Silicat mit Cer – Präparation,Charakterisierung und Struktur

Ce₂Ti₂SiO₉ – the First Titanate‐Silicate with Cerium – Preparation, Characterization, and Structure Ce₂Ti₂SiO₉ was synthesized by chemical vapour transport in a temperature gradient (1050 °C → 900 °C) using Ce₂Ti₂O₇ as precursor and ammoniumchloride as transport agent. SiO₂ was provided from the wall of the used silica tubes. The chemical composition of the crystals was determined by EDX and EELS analysis. The structure of Ce₂Ti₂SiO₉ was determined and refined to R1 = 0.025, _wR2 = 0.067, respectively. The monoclinic phase crystallizes in the space group C2/m (No. 12) with a = 16.907(3) Å, b = 5.7078(8) Å, c = 7.574(2) Å, β = 111.38(2)° and Z = 4. Ti is octahedral, Si is tetrahedral surrounded by oxygen. Ce(1) is coordinated by eight, Ce(2) by ten oxygen atoms. There are edge connected chains of Ti(1)–O‐octahedra parallel [010] which are connected along [001] with each other by Ti(2)–O‐octahedra‐pairs and Si–O‐tetrahedra.     

Synthese,Struktur und Eigenschaften der tantalreichen Silicidchalkogenide Ta15Si2QxTe10–x (Q = S,Se)

Synthesis, Structure, and Properties of the Tantalum‐rich Silicide Chalcogenides Ta₁₅Si₂Q_xTe_10–x (Q = S, Se) The quaternary tantalum silicide chalcogenides Ta₁₅Si₂Q_xTe_10–x (Q = S, Se) are accessible from proper, compacted mixtures of the respective dichalcogenides, silicon and elemental tantalum at 1770 K in sealed molybdenum tubes. The structures were determined from the strongest X‐ray intensities of fibrous crystals with cross sections of about 3 μm and confirmed by fitting the profile of single phase X‐ray diffractograms. The phases Ta₁₅Si₂S_3.5Te_6.5 and Ta₁₅Si₂Se_3.5Te_6.5 crystallize in the monoclinic space group C2/m with two formula units per unit cell, a = 2393.7(1) pm, b = 350.08(2) pm, c = 1601.2(1) pm, β = 124.700(4)°, and a = 2461.3(2) pm, b = 351.70(2) pm, c = 1601.7(1) pm, β = 124.363(5)°, respectively. Tri‐capped trigonal prismatic Ta₉Si clusters stabilized by encapsulated Si atoms can be seen as the characteristic unit of the structure. The clusters are fused into twin columns which are connected by additional Ta atoms, thus forming corrugated layers. The remaining valences at the surfaces of the layered Ta–Si substructure are saturated by those of chalcogen atoms which are coordinated only from one side by three, four or five Ta atoms. Few bridging covalent Ta–S–Ta and Ta–Se–Ta bonds and, otherwise, dispersive interactions between the Q atoms hold these nearly one nanometer wide slabs together. The phases are moderate metallic conductors. There is no evidence for any electronic instability within 10–310 K in spite of the high anisotropy of the structures.     

Synthese und Struktur von Tetrachloro[4-tert-butyl-2(diphenylphosphanyl-κP-methyl)phenolato-κO]tantal(V), ein neuartiger TaV-Komplex mit einem chelatisierenden Aryloxyphosphanliganden

Synthesis and Structure of Tetrachloro[4- tert -butyl-2(diphenylphosphanyl-κP-methyl)phenolato-κO]tantalum(V), a Novel Ta^V Complex with a Chelating Aryloxy Phosphane Ligand 4-tert-Butyl-2-(diphenylphosphanylmethyl)anisol ( 1 ) is prepared from 2-chlormethyl-4-tert-butylanisol and potassium diphenylphosphide in very good yields as a novel oxygen-phosphorus compound with potentially hemilabile ligand properties. Compound 1 reacts with tantalum pentachloride under cleavage of methylchloride revealing the complex tetrachloro[4-tert-butyl-2-(diphenylphosphanyl-κP-methyl)phenolato-κO]tantalum(V) ( 2 ) with a distorted octahedrally coordinated tantalum atom and a chelating aryloxy phosphane ligand. Complex 2 crystallizes in the tetragonal, chiral space group P4₁2₁2 with a = 11.719(5), c = 37.95(5) Å, V = 5171(7) ų, Z = 8. ³¹P NMR spectroscopic studies of 2 establish the coordination of the phosphane unit to the Ta^V center in solution.     

Crystal Structures of MBi2Br7 (M = Rb,Cs) – Filled Variants of AX7 Sphere Packing

The reinvestigation of the pseudo‐binary systems MBr–BiBr₃ (M = Rb, Cs) revealed two new phases with composition MBi₂Br₇. Both compounds are hygroscopic and show brilliant yellow color. The crystal structures were solved from X‐ray single crystal diffraction data. The isostructural compounds adopt a new structure type in the triclinic space group P$\bar{1}$ . The lattice parameters are a = 755.68(3) pm, b = 952.56(3) pm, c = 1044.00(4) pm, α = 76.400(2)°, β = 84.590(2)°, γ = 76.652(2)° for RbBi₂Br₇ and a = 758.71(5) pm, b = 958.23(7) pm, c = 1060.24(7) pm, α = 76.194(3)°, β = 83.844(4)°, γ = 76.338(3)° for CsBi₂Br₇. The crystal structures consist of M⁺ cations in anticuboctahedral coordination by bromide ions and bromidobismuthate(III) layers ²_∞[Bi₂Br₇]^–. The 2D layers comprise pairs of BiBr₆ octahedra sharing a common edge. The Bi₂Br₁₀ double octahedra are further connected by common vertices. The bismuth(III) atoms increase their mutual distance in the double octahedra by off‐centering so that the BiBr₆ octahedra are distorted. The CsBi₂Br₇ type can be interpreted as a common hexagonal close sphere packing of M and Br atoms, in which 1/4 of the octahedral voids are filled by Bi atoms. The structure type was systematically analyzed and compared with alternative types of common packings. The existence of a compound with the suggested composition CsBiBr₄ could not be verified experimentally.     

A novel Na–O–Ni–O–Ni bridging complex of Cl‐HXTA,where Cl‐HXTA is 2,6‐bis{[bis­(carboxyl­ato­methyl)­amino]­methyl}‐4‐chloro­phenolate

In the structure of the title compound, hepta­aqua‐1κ³O,2κ²O,3κ²O‐(μ₃‐2,6‐bis{[bis­(carboxyl­ato­methyl)­amino]methyl}‐4‐chloro­phenolato‐1κO;2κ⁴O,O′,N,O¹;3κ⁴O¹N′,O′′,O′′′)dinickel(II)­sodium(I) pentahydrate, [NaNi₂(C₁₆H₁₄ClN₂O₉)(H₂O)₇]·5H₂O or [Ni₂(Cl‐HXTA)(H₂O)₄{Na(H₂O)₃}]·5H₂O, the trinuclear complex unit consists of two distorted NiNO₅ octahedra bridged by a phenolate O atom and an NaO₄ tetrahedron bridged to one of the Ni octahedra by a carboxylate O atom. There are four intramolecular hydrogen bonds forming four six‐membered rings in the complex and the complex mol­ecules are connected to each other by a very complicated hydrogen‐bond network.     

Re‐evaluation of the X‐ray Crystal Structure of [Ta4F20] and the Synthesis and Characterization of a Series of Mixed‐Metal Pentafluorides of Niobium and Tantalum

The direct fluorination of intimately mixed niobium and tantalum powders gives a range of mixed‐metal pentafluorides [Nb_xTa_4‐xF₂₀] (x = 1 2 , 2 3 , 3 4 ) as discreet species isostructural with tantalum pentafluoride (x = 0 1 ). The crystal structures of 1–4 are indistinguishable by X‐ray crystallography. Complex 1 crystallizes in the monoclinic space group C2/m with a = 9.5462(13), b = 14.3578(19), c = 5.0174(7) Å, β = 97.086(2)°, Z = 2. The geometry about the tantalum atom is distorted octahedral with 2 short and 2 slightly longer Ta‐F_terminal, and 2 Ta‐F_bridging distances. The angles at the bridging fluorine atoms are 172.9(5)°.     

Zr6STe2 – ein zirconiumreiches Sulfidtellurid mit einer Zr3Te‐Teilstruktur vom Re3B‐Typ

Zr₆STe₂ – a Zirconium‐rich Sulfide Telluride with a Zr₃Te Partial Structure of the Re₃B Type Zr₆STe₂ is accessible through the reduction of a mixture of ZrTe₂ and ZrS₂ with zirconium in fused tantalum tubes at 1520 K. The spatially averaged crystal structure of Zr₆STe₂ is described in the space group Cmcm, a = 377.81(4), b = 1156.4(1), c = 887.96(8), Z = 2, Pearson symbol oC18, 320 reflexions (I > 2σ(I)), 22 variables, R_w(I) = 0.088. Zr₆STe₂ crystallizes in a unique structure type, which can be seen as a filled Re₃B type structure. The tellurium atoms are surrounded by nine zirconium atoms situated at the vertices of a distorted, tricapped trigonal prism. The Zr₉Te tetrakaidecahedra are connected by common triangular prism faces parallel [100], edges approximately along [001] and common vertices along [010], thus forming a three‐dimensional tetrakaidecahedral network [Zr_9/3Te], which is decisively stabilized by homonuclear Zr–Zr‐interactions. The tetrakaidecahedra are arranged in such a way, that Zr₆ octahedra occur. The octahedra are arranged into layers by sharing edges parallel [100] and vertices along [001]. As a result of a distortion of the structure, every second octahedron is expanded to such an extent as to be able to smoothly accommodate sulfur atoms. According to the modulation of the diffraction intensities, the vacancy ordering in adjacent layers of octahedra occurs independently of each other.     

Hydrogen‐Bonding in Cyclic 2‐(3‐Oxo‐3‐phenylpropyl)‐Substituted 1,3‐Diketones: 17O‐NMR Spectra and X‐Ray Structure Determination

Structures of cyclic 2‐(3‐oxo‐3‐phenylpropyl)‐substituted 1,3‐diketones 4a – c were determined by ¹⁷O‐NMR spectroscopy and X‐ray crystallography. In CDCl₃ solution, compounds 4a – c form an eight‐membered‐ring with intramolecular H‐bonding between the enolic OH and the carbonyl O(11)‐atom of the phenylpropyl group, as demonstrated by increased shielding of specifically labeled 4a – c in the ¹⁷O‐NMR spectra (Δδ(¹⁷O(11))=36 ppm). In solid state, intermolecular H‐bonding was observed instead of intramolecular H‐bonding, as evidenced by the X‐ray crystal‐structure analysis of compound 4b . Crystals of compound 4b at 293 K are monoclinic with a=11.7927 (12) Å, b=13.6230 (14) Å, c=9.8900 (10) Å, β=107.192 (2)°, and the space group is P2₁/c with Z=4 (refinement to R=0.0557 on 2154 independent reflections).