Trigonal-planare CuX3-Gruppen in Cu2Mo6X14, X = Cl,Br, I

Trigonal Planar CuX₃-Groups in Cu₂Mo₆X₁₄, X = Cl, Br, I Cu₂Mo₆Cl₁₄ (I), Cu₂Mo₆Br₁₄ (II) and Cu₂Mo₆I₁₄ (III) were synthesized by thermal treatment of corresponding mixtures of copper(I) and molybdenum(II) halides. The crystal structures were determined by single crystal X-ray analyses. I and II show isotypism, cubic, Pn3 (no. 201, sec. setting), Z = 4, I: a = 12.772(3) Å, II: a = 13.350(2) Å. III shows a new structural type, orthorhombic, Pbca (No. 61), Z = 4, a = 16.058(3) Å, b = 10.643(2) Å, c = 16.963(3) Å. Trigonal planar CuX₃ units were found in I? III. Structural behaviour relations are discussed, especially with regard to ionic conductivity.     

Supramolecular inclusion complexes of a star polymer containing cholesterol end‐capped poly(ε‐caprolactone) arms with β‐cyclodextrin

A novel hexa‐armed and star‐shaped polymer containing cholesterol end‐capped poly(ε‐caprolactone) arms emanating from a phosphazene core (N₃P₃‐(PCL‐Chol)₆) was synthesized by a combination of ring‐opening polymerization and “click” chemistry techniques. For this purpose, the terminal ? OH groups of the synthesized precursor (N₃P₃‐(PCL‐OH)₆) were converted into –Chol through a series of reaction. Both N₃P₃‐(PCL‐OH)₆ and N₃P₃‐(PCL‐Chol)₆ were then employed in the preparation of supramolecular inclusion complexes (ICs) with β‐cyclodextrin (β‐CD). The latter formed ICs with β‐CD in higher yield. The host–guest stoichiometry (ε‐CL:β‐CD, mol:mol) in the ICs of N₃P₃‐(PCL‐Chol)₆ was found to be 1.2. The formation of supramolecular ICs of N₃P₃‐(PCL‐Chol)₆ with β‐CD was confirmed by using Fourier transform infrared (FTIR) and ¹H nuclear magnetic resonance (NMR) spectroscopic methods, wide‐angle X‐ray diffraction (WAXD), and thermal analysis techniques. WAXD data showed that the obtained ICs with N₃P₃‐(PCL‐Chol)₆ had a channel‐type crystalline structure, indicating the suppression of the original crystallization of N₃P₃‐(PCL‐Chol)₆ in β‐CD cavities. Moreover, the thermal stabilities of ICs were found to be higher than those of the free star polymer and β‐CD. Furthermore, the surface properties of N₃P₃‐(PCL‐Chol)₆ and its ICs with β‐CD were investigated by static contact angle measurements. The obtained results proved that the wettability of N₃P₃‐(PCL‐Chol)₆ successfully increased with the formation of its ICs with β‐CD. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 3406–3420     

Der thermische Abbau von MoBr3 → Mo6Br12 → Mo

Thermal Decomposition of MoBr₃ → Mo₆Br₁₂ → Mo During the thermal decomposition of MoBr₃ → Mo₆Br₁₂ (reaction (1)) the reorganization (crystallization) of the solid Mo₆Br₁₂ is easy, compared with the reorganization of Nb₆Cl₁₄ in the similar reaction (2). This is traced back to the large reduction of the solid volume in eq. (1) compared with eq. (2). By mass spectroscopy the ions Mo₂Br₆⁺ and Mo₂Br₅⁺ are observed, but not the neutral molecule MoBr₃. (The ions MoBr₃⁺ e. g. originate from MoBr₄).     

First-Principles Study of Ultrathin Molybdenum Sul des Nanowires: Electronic and Catalytic Hydrogen Evolution Properties

Molybdenum sulfides nanomaterials, such as one-dimensional (1D) nanotubes, nanoribbons, and two-dimensional (2D) nanosheets, have attracted intensive research interests for their novel electronic, optical, and catalytic properties. On the basis of first-principles calculation, here, we report a new series of 1D ultrathin molybdenum sulfides nanowires, including Mo₂S₆、Mo₃S₆ and Mo₆S₁₀ nanowires. Our results demonstrate that these ultrathin nanowires are both thermal and lattices dynamically stable, confirmed with the calculated phonon spectrum and Born-Oppenheimer molecular dynamic simulation at the temperature up to 600 K. The calculated elastic constant is 21.33, 103.22, and 163.00 eV/? for Mo₂S₆, Mo₃S₆, and Mo₆S₁₀ nanowires, respectively. Mo₂S₆ and Mo₃S₆ nanowires are semiconductors with band gap of 1.55 and 0.46 eV, while Mo₆S₁₀ nanowires is metal, implying their potential applications in electronics and optoelectronics. In particular, ultrathin molybdenum sulfides nanowires can be used as catalysts for hydrogen evolution reaction. The calculated Gibbs free energy change for hydrogen evolution is about -0.05 eV for Mo₂S₆ nanowire, comparable with those of Pt and H-MoS₂. The prediction of these 1D molybdenum sulfides nanowires may enrich the 1D family molybdenum sulfides and make a supplement to understand the high performance of hydrogen evolution reaction in transition-metal dichalcogenides.     

Thermal Decomposition of (NH4)2[Mo3S(S2)6] · nH2O

The thermal decomposition of (NH₄)₂[Mo₃S(S₂)₆] · nH₂O was studied by DTA/TG, infrared spectroscopy, X-ray diffraction, determination of specific surfaces and temperature programmed desorption measurements. The results are reported and discussed with respect to the stability of the Mo^IV-triangle system which is retained during the thermal treatment up to the formation of hexagonal MoS₂, which can be understood nicely from a mechanistic point of view.     

Synthesis and structure of an open-type trinuclear molybdenum cluster compound[Mo_3(μ_3-S)(μ-S)_2-(μ-OAc)(S_2CNC_4H_8)_3(O)_2]·0.5CH_2Cl_2·2H_2O

The title compound was prepared by the reaction of Mo_3S_4(dtp)_4(H_2O)[ctp=S_2P(OEt)_2]with NaOAc·3H_2O and C_4H_8NCS_2NH_4.Crystallographic data:[Mo_3(μ_3-S)(μ-S)_2(μ-OAc)-(S_2CNC_4H_8)_3(O)_2]·0.5CH_2CI_2·2H_2O,Mr=980.18,triclinic,space group P,α=12.360(3),b=16.653(6),c=9.206(2)A,α=101.97(2),β=108.32(2),γ=86.14(3)°.V=1759.6(9)A~3,Z=2,Dc=1.85 g/cm~3,F(000)=962,μ(Mo K_α)=16.53 cm~(-1).Final R=0.044 for 4301 reflections with I≥3σ(I).This compoundmay be regarded as a mixed-valent trinuclear molybdenum cluster{Mo_2(V)Mo(Ⅳ)(μ_3-S)(μ-S)_2-(μ-OAc)(S_2CNC_4H_8)_3(O)_2}.The Mo-Mo distances are 2.783(1),2.833(1)and 3.374(2)A in the Mo_3non-equilateral triangle and there exist only two Mo-Mo bonds.The cluster was obtained by oxi-dation and ligand substitution of{Mo_3(μ_3-S)(μ-S)_3[μ-S_2P(OEt_2)][S_2P(OEt)_2]_3(H_2O)}.     

Synthesis and crystal structure of a cubanelike tetranuclear molybdenum cluster compound {Mo4)(μ3-S)3)(μ3-O)[S2P(OEt)2]6} · 3CH3CN

A tetranuclear molybdenum cluster compound {Mo₄(μ₃-S)₃(μ₃-O)[S₂P(OEt)₂]₅} · 3CH₃CN was obtained by the reaction of MoCl₃ · 3H₂O with P₂S₅ in ethanol and then recrystallization from acetonitrile. The compound crystallizes in the trigonal system belonging to the space group R3 with the following cell dimensions: a = b = c = 12.852 (3) Å, α = β = γ = 108.37 (2)°, V =1697.3ų Z = 1, D_c. = 1.693g.cm^?3. The structure was solved by heavy atom method and refined by full-matrix least-squares to R = 0.072 for 1781 reflections with I≥3σ(I). The results of the structure determination indicate that the cluster skeleton possesses a cubanelike cluster core formed by four Mo atoms located in a distored tetrahedron with three S atoms and one O atom as its triple bridging atoms. There are two sets of bond distances, i.e. 2.700 (1) and 2.831(1) Å in the six Mo—Mo bonds. Taking the Mo cluster core as a whole, it has a formal oxidation state of +14, leaving ten electrons to form the metal-metal bonds. Thus each Mo—Mo bond has an average bond order of 5/6.     

Thiochloroanionen von Molybdän(IV). Die Kristallstruktur von (NEt4)3[Mo3(μ3-S)(μ-S2)3Cl6]Cl · CH2Cl2 Kristallstruktur,EPR-Spektrum und magnetische Eigenschaften von (NEt4)2[Mo2(μ-S2)(μ-Cl)2Cl6]

Thiochloro Anions of Molybdenum (IV). Crystal Structure of (NEt₄)₃[Mo₃(μ₃-S)(μ-S₂)₃Cl₆]Cl μ CH₂Cl₂. Crystal Structure, Magnetic Properties, and EPR-Spectrum of (NEt₄)₂ [Mo₂(μ-S₂)(μ-Cl)₂Cl₆] From molybdenum pentachloride and tetraethylammonium hydrogensulfide in CH₂Cl₂ an insoluble product of composition (NEt₄)₂[Mo₂S₃Cl₉] was obtained along with a brown solution, from which (NEt₄)₂[Mo₂(S₂)Cl₈] was crystallized. The insoluble product and NEt₄Cl react in CH₂Cl₂ to yield, among others, (NEt₄)₃[Mo₃(S)(S₂)₃Cl₆]Cl · CH₂Cl₂. The latter crystallizes in the orthorhombic space group Pnma, a = 2495.8, b = 1501.2, c = 1295.6 pm, Z = 4. According to the crystal structure determination (3070 observed reflexions, R = 0.049) the [Mo₃(S)(S₂)₃Cl₆]^2? ion consists of an Mo₃ triangle with Mo? Mo bonds, each side of the triangle is bridged by disulfido groups and one sulfur atom is capped over the Mo₃ triangle; the single chloride ion is looseley associated to three S atoms. (NEt₄)₂[Mo₂(S₂)Cl₈] also crystallizes in the space group Pnma, a = 1425.6, b = 1129.9, c = 2004.7 pm, Z = 4; structure determination with 1703 observed reflexions, R = 0.061. In the [Mo₂(S₂)Cl₈]^2? ion the Mo atoms are bridged via one disulfido group and two chlorine atoms. There is a Mo? Mo bond, but according to the magnetic properties and the EPR spectrum each Mo atom still possesses one unpaired electron.     

Hydrolytic degradation of poly(ε‐caprolactone) with different end groups and poly(ε‐caprolactone‐co‐γ‐butyrolactone): characterization and kinetics of hydrocortisone delivery

Asymmetric telechelic α‐hydroxyl‐ω‐(carboxylic acid)‐poly(ε‐caprolactone) (HA‐PCL), α‐hydroxyl‐ω‐(benzylic ester)‐poly(ε‐caprolactone) (HBz‐PCL), and an asymmetric telechelic copolymer α‐hydroxyl‐ω‐(carboxylic acid)‐poly(ε‐caprolactone‐co‐γ‐butyrolactone) (HA‐PCB) were synthesized by ring‐opening polymerization of ε‐caprolactone (CL). CL and CL/γ‐butyrolactone mixture were used to obtain homopolymers and copolymer respectively at 150°C and 2 hr using ammonium decamolybdate (NH₄) [Mo₁₀O₃₄] (Dec) as a catalyst. Water (HA‐PCL and HA‐PCB) or benzyl alcohol (HBz‐PCL) were used as initiators. The three polylactones reached initial molecular weights between 2000 and 3000 Da measured by proton nuclear magnetic resonance (¹H‐NMR). Compression‐molded polylactone caplets were allowed to degrade in 0.5 M aqueous p‐toluenesulfonic acid at 37°C and monitored up to 60 days for weight loss behavior. Data showed that the copolymer degraded faster than the PCL homopolymers, and that there was no difference in the weight loss behavior between HA‐PCL and HBz‐PCL. Caplets of the three polylactones containing 1% (w/w) hydrocortisone were placed in two different buffer systems, pH 5.0 with citrate buffer and pH 7.4 with phosphate buffer at 37°C, and monitored up to 50 days for their release behavior. The release profiles of hydrocortisone presented two stages. The introduction of a second monomer in the polymer chain significantly increased the release rate, the degradation rate for HA‐PCB being faster than those for HBz‐PCL and HA‐PCL. At the pH studied, only slight differences on the liberation profiles were observed. SEM micrographs indicate that hydrolytic degradation occurred mainly by a surface erosion mechanism. Copyright © 2009 John Wiley & Sons, Ltd.     

Stabilization of Mo6S8 by halogens; new superconducting compounds: Mo6S6Br2, Mo6S6I2

We present a study of the properties of the series Mo₆X_8?xY_x (X = S, Se, Te; Y = Br, I) having the hexagonal rhombohedral structure of the PbMo₆S₈ type. For X = S we have found two new superconducting compounds Mo₆S₆Br₂ and Mo₆S₆I₂, having critical temperatures of 13.8 and 14.0°K, respectively. We further find that Mo₆Te₈ becomes superconducting (T_c ≈ 2.6°K) upon substitution of Te by small quantities of iodine, and that in the case of Mo₆Se₈ substitution of a Se atom by a halogen, raises T_c up to about 7.6°K.     

The synthesis and crystal structure of a trinuclear molybdenum cluster compound [Mo3(μ-O)(μ-S)3(μ(μ-OAc)2(dtp)2·(Py)]·0.5H2O

[Mo₃,OS₃(dtp)₄(H₂O)] reacts with NaOAc·3H₂O in Py to give the title compound. The crystal data are as follows: [Mo₂OS₃)(OAc)₂(dtp)₂·Py]?0.5H,O(dtp = [S₃P(OC₂H₅)₂]^?, Py = C₅H₅N); M = 976.64; triclinic; space group P1 ; a=11.704(5), b=14.169(7), c= 11.688 (5) Å α=109.94(4) β = 91.53(4), γ = 91.93(4)°; V= 1819(1) Ų; Z=2; D_c = 1.78 g·cm^?3 λ(Mo Kα) = 0.71069 Å μ=15.15 cm^?1; F(000) = 970 T=296 K; final R=0.071 for 1652 reflections with I>3σ(I). In the molecule, the [Mo₃OS₃] core is surrounded by two bridging OAc groups and two terminal chelate dtp groups attached to the {Mo₃} triangle in a symmetric style, and the Py ligand is coordinated to the Mo atom at the apex of {Mo₃} triangle with the nitrogen. This novel configuration is obtained for the first time with Mo—N bond length being 2.27 (2) Å and three Mo—Mo bond lengths 2.584 (4), 2.587 (4) and 2.657(4) Å, respectively. As a whole, the molecule has a virtual C₂ symmetry.     

Das Addukt von BiCl3 mit Mo6Cl12: [BiCl]-Hanteln in der Struktur von [BiCl][Mo6Cl14]

The Adduct of BiCl₃ and Mo₆Cl₁₂: [BiCl] Dumbbells in the Structure of [BiCl][Mo₆Cl₁₄] MoCl₃ reacts under decomposition to MoCl₂ and Cl₂ with BiCl₃ in a sealed evacuated glass ampoule at 550 °C to form light red crystals of [BiCl][Mo₆Cl₁₄]. The crystal structure determination (monoclinic, C 2/c, a = 1268.1(4) pm, b = 1304.6(3) pm, c = 2571.9(8) pm, β = 91.79(3)°, Z = 8) shows that the structure is built of [(Mo₆Cl₈)Cl₆] units containing nearly regular octahedral Mo₆ clusters. These units are arranged in the motiv of a cubic closest packing. The octahedral interstices contain [BiCl] dumbbells with a Bi–Cl bond length of 249 pm. The coordination sphere of the Bi atom is completed by six weaker Bi–Cl-contacts of 275 to 308 pm length to a distorted monocapped trigonal prism. Neglecting the secondary Bi–Cl bonds, the title compound can be formulated as [(BiCl)²⁺][(Mo₆Cl₁₄)^2–].     

[ReIII(thiourea-S)6]Cl3 · 4 H2O and [ReIII(N-methylthiourea-S)6]Cl3 as Precursors to other ReIII Complexes: a Kinetic Study in Aqueous Media. Crystal Structure of [ReIII(N-methylthiourea-S)6](PF6)3 · H2O

Capability of [Re^III(tu-S)₆]Cl₃, where tu = thiourea, as a precursor to other Re^III complexes by ligand substitution in aqueous medium is studied. For the decomposition of [Re(tu-S)₆]Cl₃, experiments suggest pseudo first order kinetics and observed rate constants vary from 1.3 × 10^–2 to 9.6 × 10^–2 min^–1 in the pH range 2.80–5.04. Experiments in presence of incoming ligand (ethylendiaminetetraacetic acid or diethylentriaminepentaacetic acid) show that ligand substitution is significantly slower than decomposition of the precursor, even when pH and temperature are modified. Similar results were obtained working with [Re^III(Metu-S)₆]Cl₃, where Metu = N-methylthiourea. Molecular structure of [Re^III(Metu-S)₆](PF₆)₃ · H₂O was determined by single crystal X-ray diffractometry. The coordination polyhedron around the Re ion is a distorted octahedron. The six methylthiourea ligands are bonded to the metal through the sulfur atoms [bond lengths range from 2.409(2) to 2.451(2) Å].     

Characterization and cytotoxicity studies of thiol‐modified polystyrene microbeads doped with [{Mo6X8}(NO3)6]2– (X = Cl,Br, I)

Halide octahedral molybdenum clusters [{Mo₆X₈}L₆]^n– possess luminescence properties that are highly promising for biological applications. These properties are rather dependent on the nature of both the inner ligands X (i.e. Cl, Br, or I) and the apical organic or inorganic ligands L. Herein, the luminescence properties and the toxicity of thiol‐modified polystyrene microbeads (PS‐SH) doped with [{Mo₆X₈}(NO₃)₆]^2– (X = Cl, Br, I) were studied and evaluated using human epidermoid larynx carcinoma (Hep2) cell cultures. According to our data, the photoluminescence quantum yield of {Mo₆I₈}@PS‐SH is significantly higher (0.04) than that of {Mo₆Cl₈}@PS‐SH (<0.005) and {Mo₆Br₈}@PS‐SH (<0.005). Treatment of Hep2 cells with {Mo₆X₈}@PS‐SH showed that all three types of doped microbeads had no significant effect on the viability and proliferation of the cells. Copyright © 2016 John Wiley & Sons, Ltd.     

Synthese,Eigenschaften und Kristallstruktur von Cu3Mo8O23X2 (X = Cl,Br, I)

Synthesis, Properties, and Crystal Structure of Cu₃Mo₈O₂₃X₂ (X = Cl, Br, I) Single crystals of the Cu₃Mo₈O₂₃X₂ compounds were grown by chemical transport reactions at the lower temperature of a gradient 873–823 K without extra transport agent (auto transport). As DTA/TG measurements indicate, the gaseous compounds, necessary for chemical transport reactions, are formed by partial decomposition of Cu₃Mo₈O₂₃X₂ at 873 K. Cu₃Mo₈O₂₃Br₂ crystallizes with the orthorombic space group Pbcm (a = 4.021(1), b = 22.978(2), c = 21.673(2) Å, Z = 4). The crystal structure consists of pentagonal columns ¹_∞[Mo₆O₇O_20/2] linked by additional MoO_6/2 octahedra. All the polyhedra(pentagonal bipyramide, octahedra) are distorted. Infinite chains ¹_∞[Cu₃Br₂] along [100] are arranged in tunnels with s‐like square shape, left open by the pentagonal columns. Cu₃Mo₈O₂₃Cl₂ (a = 4.010(1), b = 22.942(2), c = 21.639(2) Å) and Cu₃Mo₈O₂₃I₂ (a = 4.052(1), b = 23.075(2), c = 21.719(2) Å) are isotypic.     

Oxometallate neuen Typs: Über Ba3NaNbO6 und Ba3NaTaO6

Oxometallates of a new Type: On Ba₃NaNbO₆ and Ba₃NaTaO₆ For the first time in form of colourless, transparent single crystals of Ba₃NaNbO₆ [annealed mixtures of BaO, Na₂O and Nb₂O₅, Ba : Na : Nb = 3.3 : 1.1 : 1, Ni-cylinder, 1100°C, 3d] as well as Ba₃NaTaO₆ [annealed mixtures of BaO, Na₂O and Ta₂O₅, Ba : Na : Ta = 3.3 : 1.1 : 1, Ni-cylinder, 1100°C, 3d] have been prepared. The crystal structure was solved by fourcycle-diffractometer data [Ba₃NaNbO₆: Mo? Kα , 356 out 356 I₀ (hkl), space group R3 c with a = 1026.6(1)pm, c = 1195.3(2)pm (Guinier-Simon powder data), Z = 6, R = 2.4%, R_w = 2.0% and Ba₃NaTaO₆: Ag? Kα , 498 out of 498 I₀ (hkl), space group R3 c with a = 1027.6(1)pm, c = 1196.0(2)pm (Guinier-Simon powder data), Z = 6, R = 4.9%, R_w = 4.4%], parameters see text. The Ba₃M part of structure (M = Nb, Ta) corresponds to a slightly (hexagonal) deformed Nb₃Al arrangement with Na inserted along [001] between adjacent M^v, which are nearly perfectly octahedrally surrounded by 6 O. The structural relations are deduced by Schlegel Diagrams. The Madelung Part of Lattice Energy, MAPLE, and Effective Coordination Numbers, ECoN, the latter derived from Mean Effective Ionic Radii, MEFIR, as well as Charge Distribution, CHARDI, are calculated.     

Elektronenstruktur von strukturell offenen Derivaten des [Mo6X14]2−-Clusters: [Mo5Cl13]2− und [Mo4I11]2−

Electronic Structure of Structural Open Derivatives of the [Mo₆X₁₄]^2?-Cluster: [Mo₅Cl₁₃]^2? and [Mo₄I₁₁]^2? The electronic structure of structural open derivatives of the [Mo₆X₁₄]^2?-cluster [Mo₅Cl₁₃]^2? and [Mo₄I₁₁]^2? has been studied by the EHMO method. In [Mo₅Cl₁₃]^2? 9 occupied MO's with dominant Mo4d character are responsible for the formation of the 8 metal-metal bonds. In [Mo₄I₁₁]^2? the stronger covalent character of the Mo? I bonds affects the localization and the energy of molecular orbitals and also the charge distribution. The metal-metal bonds are formed by 8 MO's containing considerable participation of halogen AO's contrary to the chloride cluster. There is no bonding between the Mo atoms at the wing tips of the Mo₄ butterfly and the reason for decreasing the dihedral angle between the Mo₃ planes in [Mo₄I₁₁]^2? compared with the octahedral angle is apparently the stabilization of the whole system (Mo? Mo and Mo? I bonds). The unpaired electron occupies in both clusters a slightly antibonding (with regard to the Mo? Mo bonds) orbital.     

Molybdän‐ und Wolfram‐Komplexe mit MNS‐Sequenzen. Die Kristallstrukturen von [MoCl3(N3S2)(1,4‐Dioxan)2] und [Mo2Cl2(μ‐NSN)2(μ‐O)(NCMe3)(OCMe3)2]2

Molybdenum and Tungsten Complexes with MNS Sequences. Crystal Structures of [MoCl₃(N₃S₂)(1,4‐dioxane)₂] and [Mo₂Cl₂(μ‐NSN)₂(μ‐O)(NCMe₃)(OCMe₃)₂]₂ The cyclo‐thiazeno complexes [Cl₃MNSNSN]₂ of molybdenum and tungsten react with 1,4‐dioxane in dichloromethane suspension to give the binuclear donor‐acceptor complexes [μ‐(1,4‐dioxane){MCl₃(N₃S₂)}₂] which are characterized by IR spectroscopy. With excess 1,4‐dioxane the molybdenum compound forms the complex [MoCl₃(N₃S₂)(1,4‐dioxane)₂] in which, according to the crystal structure determination, one of the dioxane molecules coordinates at the molybdenum atom, the other one at one of the sulfur atoms of the cyclo‐thiazeno ring. The μ‐(NSN^2–) complex [Mo₂Cl₂(μ‐NSN)₂(μ‐O)(NCMe₃)(OCMe₃)₂]₂ has been obtained by the reaction of [MoN(OCMe₃)₃] with trithiazyle chloride in carbontetrachloride solution. According to the crystal structure determination this compound forms centrosymmetric dimeric molecules via two of the nitrogen atoms of two of the μ‐(NSN) groups to give a Mo₂N₂ fourmembered ring. [MoCl₃(N₃S₂)(1,4‐dioxane)₂]: Space group P2₁/c, Z = 4, lattice dimensions at –70 °C: a = 1522.9(2); b = 990.3(1); c = 1161.7(1) pm; β = 106.31(1)°, R₁ = 0.0317. [Mo₂Cl₂(μ‐NSN)₂(μ‐O)(NCMe₃)(OCMe₃)₂]₂ · 4 CCl₄: Space group P2₁/c, Z = 2, lattice dimensions at –83 °C: a = 1216.7(1); b = 2193.1(2); c = 1321.8(1) pm; β = 98.23(1)°; R₁ = 0.0507.     

Synthese und Eigenschaften von Sr3Mo1.5Zn0.5O7‐δ, einer Phase mit perowskitverwandter Schichtstruktur

Synthesis and Properties of the Layered Perovskite Phase Sr₃Mo_1.5Zn_0.5O_7‐δ The new layered perovskite phase Sr₃Mo_1.5Zn_0.5O_7‐δ was synthesized by solid state reaction using a Zn/ZnO oxygen buffer. The crystal structure was refined from X‐ray powder pattern by the Rietveld method. The compound crystallizes tetragonal in the space group I4/mmm (no. 139) with the lattice parameters a = 3.9631(3) Å, c = 20.583(1) Å. An oxygen deficiency corresponding to δ ≈ 0.25 was determinated, indicating the presence of molybdenum in mixed valence (Mo⁴⁺ and Mo⁶⁺).     

Kondensierte Al6‐Ringe in den Subiodiden La3Al2I2 und La2Al2I

Condensed Al₆ Rings in the Subiodides La₃Al₂I₂ and La₂Al₂I The subiodides La₃Al₂I₂ and La₂Al₂I are reported. The compounds were prepared from stoichiometric mixtures of lanthanum, aluminium, and LaI₃ under Ar atmosphere in sealed Ta ampoules at 920–950 °C and 980–1000 °C, respectively. La₃Al₂I₂ crystallizes in space group C2/m with a = 19.73(2) Å, b = 4.318(1) Å, c = 12.348(9) Å and β = 121.49(3)°, La₂Al₂I in P6₃/mmc with a = 4.3718(8) Å and c = 17.605(2) Å (isotypic with Gd₂Fe₂I). Both structures are characterized by sheets of trigonal prisms formed by the La atoms centered by aluminium, the latter being arranged in Al₆ rings. These rings are connected to chains in La₃Al₂I₂ (d_{Al(2)–Al(2)} = 2.550(4) Å and 2.615(2) Å, respectively) and layers (d_Al–Al = 2.533(1) Å) in La₂Al₂I. Both compounds are metallic conductors. The electronic structure of both compounds is discussed based on band structure calculations.