Zur Kenntnis der Dialkalimetalldichalkogenide β-Na2S2, K2S2, α-Rb2S2, β-Rb2S2, K2Se2, Rb2Se2, α-K2Te2, β-K2Te2 und Rb2Te2

On Dialkali Metal Dichalcogenides β-Na₂S₂, K₂S₂, α-Rb₂S₂, β-Rb₂S₂, K₂Se₂, Rb₂Se₂, α-K₂Te₂, β-K₂Te₂ and Rb₂Te₂ The first presentation of pure samples of α- and β-Rb₂S₂, α- and β-K₂Te₂, and Rb₂Te₂ is described. Using single crystals of K₂S₂ and K₂Se₂, received by ammonothermal synthesis, the structure of the Na₂O₂ type and by using single crystals of β-Na₂S₂ and β-K₂Te₂ the Li₂O₂ type structure will be refined. By combined investigations with temperature-dependent Guinier-, neutron diffraction-, thermal analysis, and Raman-spectroscopy the nature of the monotropic phase transition from the Na₂O₂ type to the Li₂O₂ type will be explained by means of the examples α-/β-Na₂S₂ and α-/β-K₂Te₂. A further case of dimorphic condition as well as the monotropic phase transition of α- and β-Rb₂S₂ is presented. The existing areas of the structure fields of the dialkali metal dichalcogenides are limited by the model of the polar covalence.     

Syntheses,Spectroscopic Studies,and Crystal Structures of Me2Sn(O2PPh2)2, Ph2Pb(O2PMe2)2, and Ph2Pb(O2PPh2)2

Me₂Sn(O₂PPh₂)₂ ( 1 ), Ph₂Pb(O₂PMe₂)₂ ( 2 ), and Ph₂Pb(O₂PPh₂)₂ ( 3 ) have been synthesized by the reactions of Me₂SnCl₂ or Ph₃PbCl with the corresponding diorganophosphinic acid in methanol. X‐ray diffraction studies show that the diorganophosphinate groups behave as double bridges between the metal atoms leading to polymeric ring‐chain structures with M₂O₄P₂ (M = Pb, Sn) eight‐membered rings. The organic groups bonded to the metal atoms are in trans‐position in the resulting octahedral arrangement around the metal atoms. The IR and the mass spectra were reported and discussed.     

Darstellung und Kristallstruktur der Pnictidoxide Na2Ti2As2O und Na2Ti2Sb2O

Preparation and Crystal Structure of the Pnictide Oxides Na₂Ti₂As₂O and Na₂Ti₂Sb₂O Na₂Ti₂As₂O and Na₂Ti₂Sb₂O were synthesized in form of very easily hydrolysed metallic-grey powders by reaction of Na₂O and TiAs resp. TiSb in sealed tantalum tubes under argon. The tetrahedral bodycentered crystallizing compounds from a modified anti-K₂NiF₄ structure type [1] (also called Eu₄As₂O-type [2,3]), space group I4/mmm (no. 139), with the lattice constants for Na₂Ti₂As₂O: a = 407.0(2) pm, c = 1528.8(4) pm and for Na₂Ti₂Sb₂O: a = 414.4(0) pm, c = 1656.1(1) pm. Magnetic measurements of powder samples of Na₂Ti₂Sb₂O show antiferromagnetic interaction within the Ti—O-layers. Superconductivity was not found by ac-shielding method down to 4 K.     

Electrochemical study of (NEt4)2Cl2FeS2MoS2 and (NEt4)2Cl2FeS2MoS2FeCl2

Summary The ability of [MoS₄]^2–, anions to be used as ligands for transition metal ions has been widely demonstrated, especially with Fe²⁺. The present study has been restricted to linear complexes such as (NEt₄)₂ [Cl₂FeS₂MoS₂] and (NEt₄)₂[Cl₂FeS₂MoS₂FeCl₂]. Their electrochemical properties are described: upon electrochemical reduction, these compounds yield MoS₂, as a black precipitate, and an iron complex in solution, assumed to be [SFeCl₂]^2–. The electrochemical reduction goes through two electron transfers, coupled with the breakdown of the molecular skeleton: a DISPl and an ECE mechanism. Depending on the solvent, the following equilibrium may be observed: [Cl₄Fe₂MoS₄]^2–[Cl₂FeMoS₄]^2–+FeCl₂. The equilibrium constant, K_D, was evaluated by differential pulse polarography. K_D is tightly related to the donor number of the solvent.     

(PPh4)2[WO2Cl3]2 · 2 CH2Cl2: Synthese,Schwingungsspektrum und Kristallstruktur

(PPh₄)₂[WO₂Cl₃]₂ · 2 CH₂Cl₂. Synthesis, Vibrational Spectrum, and Crystal Structure Depending on the stoichiometry and the solvent, dichloromethane or 1.2-dichloroethane, WO₂Cl₂ reacts with tetraphenylphosphonium chloride affording (PPh₄)₂[WO₂Cl₄] or (PPh₄)₂[WO₂Cl₃]₂, respectively. Both compounds are easily soluble in dichloromethane, from which they can be crystallized under incorporation of two molecules CH₂Cl₂ per formula unit. The crystalline compounds have been characterized by their IR and Raman spectra. According to the X-ray crystal structure analysis, (PPh₄)₂[WO₂Cl₃]₂ · 2 CH₂Cl₂ crystallizes in the triclinic space group P1 with one formula unit per unit cell (986 independent observed reflexions, R = 0.061). Lattice constants: a = 1100.2, b = 1116.9, c = 1238.4 pm, = 69.40, = 80.46 and = 85.62°. The crystals consist of PPh₄^⊕ ions, centrosymmetric [WO₂Cl₃]₂^2? anions and CH₂Cl₂ molecules. In the anions, the tungsten atoms are linked via two oxo bridges with WO distances of 184 and 252 pm. The distorted octahedral coordination around each tungsten atom is completed by three terminal chloro and one terminal oxo ligand (WO bond length 166 pm), the latter being in trans position to the longer WO bridging bond. (PPh₄)₂[WO₂Cl₄] · 2 CH₂Cl₂ also forms triclinic crystals that are isotypic with (PPh₄)₂[WOCl₅] · 2 CH₂Cl₂ and in which the anions must have orientational disorder.     

Über LaCo2P2 und andere Neue Verbindungen mit ThCr2Si2- und CaBe2Ge2-Struktur

On LaCo₂P₂ and Other New Compounds with ThCr₂Si₂- and CaBe₂Ge₂-Type Structure The compounds MCo₂P₂ (M = La, Ce, Pr, Nd, Sm, Th, U), MFe₂P₂ (M = La, Ce, U), and ThCo₂As₂ were prepared for the first time. Structure determinations from single crystal X-ray data of LaCo₂P₂ (R = 0.011; 325 F-values), CeCo₂P₂ (R = 0.023; 160 F), PrCo₂P₂ (R = 0.044; 441 F), LaFe₂P₂ (R = 0.024; 511 F), and CeFe₂P₂ (R = 0.016; 183 F) with 11 variable parameters each resulted in atomic positions within the range of the ThCr₂Si₂-type. The powder patterns of ThCo₂P₂, and ThCo₂As₂ show superstructure reflections indicating a CaBe₂Ge₂-type structure. The other compounds can be assigned to the ThCr₂Si₂-type. Chemical bonding of these can be rationalized by a simple band structure model where bonding transition metal – transition metal interactions are important.     

BaAg2S2, ein Thioargentat im CaAl2Si2-Strukturtyp

BaAg₂S₂, a Thioargentate with the CaAl₂Si₂-Type Structure BaAg₂S₂ could be obtained as crystalline powder by the reaction of barium-bis[dicyanoargentate(I)] in a stream of hydrogensulfid at 500°C. Single crystals grew at 480°C in an evacuated glass ampoule filled with a flux of potassium thiocyanate and powdery BaAg₂S₂ as solid. BaAg₂S₂ crystallises in the trigonal CaAl₂Si₂-typ structure, a = 4.386(1) Å, c = 7.194(2) Å, space group P3 m1, Z = 1. The structure was determined from four-circle diffractometer data. The silver-sulphur distances are discussed with respect to the corresponding distances of the hitherto known alkaline earth-transition metal pnictides, also crystallizing in the CaAl₂Si₂-typ structure.     

Synthesis of bridged and linked ruthenium and osmium carbonyl clusters containing a [Au2(Ph2PCH2CH2PPh2)]2+ unit. The crystal and molecular structures of Ru5C(CO)14Au2(Ph2PCH2CH2PPh2) and {Os4H3(CO)12}2Au2(Ph2PCH2CH2PPh2)

Treatment of Au₂(Ph₂PCH₂CH₂PPh₂)Cl₂ with one equivalent of the [Ru₅C(CO)₁₄]²⁻ dianion in the presence of TlPF₆ gives Ru₅C(CO)₁₄Au₂(Ph₂PCH₂CH₂PPh₂) (1) in good yield and the [{Ru₅C(CO)₁₄}₂Au₂(Ph₂PCH₂CH₂PPh₂)]²⁻ (2) anion in low yield. Complex 2 becomes the major product if 2 equivalents of [Ru₅C(CO)₁₄]²⁻ are used. Reaction of [Au₂(Ph₂PCH₂CH₂PPh₂)Cl₂] with 3 equivalents of [H₃Os₄(CO)₁₂]⁻ anion in the presence of TlPF₆ affords {H₃Os₄(CO)₁₂}₂Au₂(Ph₂PCH₂CH₂PPh₂) (3) in reasonable yield. X-ray diffraction studies of 1 and 3 show that they contain the [Au₂(Ph₂PCH₂CH₂PPh₂)]²⁺ fragment in different coordination modes.     

Synthese und Kristallstrukturen der Zink-Amido-Komplexe [Zn(NPh2)2]2 und [Zn(NPh2)2(THF)2]

Synthesis and Crystal Structures of the Zinc Amido Complexes [Zn(NPh₂)₂]₂ and [Zn(NPh₂)₂(THF)₂] Zinc diphenylamide is prepared from Zn[N(SiMe₃)₂]₂ and diphenylamine by transamination reaction. The compound is characterized by a crystal structure analysis. According to it [Zn(NPh₂)₂]₂ forms centrosymmetric dimeric molecules with Zn–N distances of 185.9 pm for the terminally bonded NPh₂^– ligand and Zn–N distances of 204.0 and 202.6 pm in the four-membered ring. From tetrahydrofuran solutions [Zn(NPh₂)₂(THF)₂] crystallizes as monomeric molecular complex with Zn–N bond lengths of 192.2 pm in average.     

Synthese von Y2O2(CN2) und Leuchtstoffeigenschaften von Y2O2(CN2):Eu

Synthesis of Y₂O₂(CN₂) and Luminescence Properties of Y₂O₂(CN₂):Eu Crystalline powders of the new compound Y₂O₂(CN₂) were prepared by solid state reactions from different mixtures of YCl₃/YOCl/Y₂O₃ and Li₂(CN₂) at temperatures between 620 °C and 650 °C. Structure refinements based on X‐ray powder diffraction revealed that trigonal Y₂O₂(CN₂) crystallizes with a structure that is closely related to that of Y₂O₂S, whereas linear N‐C‐N units replace sulphur atoms in Y₂O₂S. In addition, a hexagonal polytype of Y₂O₂(CN₂) was obtained in which a different stacking sequence of yttrium atoms creates a doubling of the c‐axis. Europium‐doped samples of Y₂O₂(CN₂) were prepared and the luminescence properties of Y₂O₂(CN₂):Eu are presented.     

Synthesis and characterization of arsacycloalkanes and their palladium and platinum complexes,and X‐ray structure of [PdCl2(PhAsCH2CH2CH2CH2CH2)2]

Reactions of PhAsCl₂ with BrMg(CH₂)_nMgBr (n = 4 or 5) in THF gave phenylarsacycloalkanes as colourless oily liquids which could be distilled under vacuum. Treatment of PhAs(CH₂)_n­with MCl₂(RCN)₂ (M = Pd or Pt; R = Ph­or Me) afforded mononuclear complexes, [MCl₂{PhAs(CH₂)_n}₂]. Reactions with [Pt₂Cl₂(μ‐Cl)₂(PEt₃)₂] gave mixed‐ligand complexes, [PtCl₂(PEt₃){PhAs(CH₂)_n]. The palladium complexes adopt a trans geometry whereas the platinum complexes exist in a cis configuration. The crystal and molecular structure of [PdCl₂(PhAsCH₂CH₂CH₂CH₂CH₂)₂] was determined by X‐ray diffraction methods. The molecule consists of a square‐planar palladium atom with trans chlorides and trans arsa ligands. The six‐membered ‘AsC₅′ ring adopts a chair conformation. Copyright © 1999 John Wiley & Sons, Ltd.     

Lithium nitride reduction of Cp2TiCl2 and CpTiCl3: The synthesis of (Cp2TiCl2), Cp2TiCl2)n,Cp2Ti(CO)2 and chlorotetratitanium and nitridohexatitanium complexes

Stoichiometric reactions of Cp₂TiCl₂ or CpTiCl₃ with Li₃N in various molar ratios result in reduction to (Cp₂TiCl)₂, (CpTiCl₂)_n and (CpTiCl)₄ and provide useful synthetic routes. Further reduction produces hexanuclear nitrido titanium clusters, Cp₈Ti₆N and Cp₈Ti₆N₃, characterised from mass spectral evidence. The nitrido clusters react with HCl to form (Cp₂TiCl)₂ and Cp₂TiCl₂. (Cp₂TiCl₂ is also obtained by reaction with Me₃SiCl. Cp₂Ti(CO)₂ is formed by the reaction between Cp₂TiCl₂ and Li₃ N in THF in the presence of CO.     

Zur Kristallstruktur von Rb2C2 und Cs2C2

On the Crystal Structure of Rb₂C₂ and Cs₂C₂ By reaction of rubidium or caesium solved in liquid ammonia with acetylene AC₂H with A = Rb, Cs was obtained, which was subsequently converted into the binary acetylide A₂C₂ in vacuum at temperatures of 520 K (Rb₂C₂) and 470 K (Cs₂C₂) using a surplus of the respective alkali metal. The crystal structures of the very air sensitive compounds were solved and refined by a combination of both neutron and X‐ray powder diffraction data. Rb₂C₂ as well as Cs₂C₂ coexist in two modifications. The hexagonal modification (P 6 2m, Z = 3) crystallises in the known Na₂O₂ structure type with two crystallographic independent sites for the C₂^2– dumbbells. For the orthorhombic modification (Pnma, Z = 4) a new structure type was found, which is related to the PbCl₂ structure type with ordered C₂^2– dumbbells occupying the Pb sites. Temperature dependent investigations between 4 K and the decomposition temperature by the means of neutron and X‐ray powder diffraction resulted in a very complex dynamic disorder of the C₂ dumbbells, which is still not completely understood. The frequencies of the C–C stretching vibration determined by the help of Raman spectroscopy fit nicely to the results obtained for other alkali metal acetylides and alkali metal hydrogen acetylides. These results seem to indicate that the electronegativity of the alkali metal has a strong influence on the frequency of the C–C stretching vibration.     

Missing Carbodiimide and Oxide Carbodiimide of Scandium: Sc2(CN2)3 and Sc2O2(CN2)

The new scandium(III) carbodiimides Sc₂(CN₂)₃ and Sc₂O₂(CN₂) were prepared by solid-state metathesis reactions between Li₂(CN₂) and ScCl₃ and, regarding Sc₂O₂(CN₂), Sc₂O₃ was added. The X-ray powder diffraction pattern refinements lead to a trigonal-rhombohedral (R3 c) crystal system for Sc₂(CN₂)₃ and to an orthorhombic (Immm) crystal system for Sc₂O₂(CN₂). The structure of Sc₂(CN₂)₃ is isotypic to the well-known rare earth carbodiimides RE₂(CN₂)₃ with the smaller cations RE = Tm, Yb, and Lu, whereas Sc₂O₂(CN₂) is not isotypic to the known RE₂O₂(CN₂) (RE = Y, La, Ce–Gd, except Pm) compounds. Both crystal structures are represented by layered arrangements of scandium, respectively scandium and oxide, alternating with carbodiimide layers.     

Metall-Schwefelstickstoff-Verbindungen. 13. Die Reaktion von [Ni(HN2S2)2] mit Basen Salze mit den Anionen [Ni(HN2S2)(N2S2)]− und [Ni(N2S2)2]2−

Metal Sulfur Nitrogen Compounds. 13. Reaction of [Ni(HN₂S₂)₂] with Bases. Salts with the Anions [Ni(HN₂S₂)(N₂S₂)]^? and [Ni(N₂S₂)₂]^2? Whereas the complex [Ni(HN₂S₂)₂] reacts with alcoholic solutions of alkaline hydroxides by double deprotonation to the anion [Ni(N₂S₂)₂]^2?, only one proton is removed by the reaction with strong organic bases like tetraalkylammonium, tetraphenylphosphonium, and tetrphenylarsonium hydroxides. The corresponding salts with the anion [Ni(HN₂S₂)(N₂S₂)]^? are formed. The salts containing the tetramethylammonium, tetraethylammonium, tetra-n-butylammonium and tetraphenylarsonium cations were isolated as rather stable, crystalline solids. The structure of the tetraphenylarsonium salt [Ph₄As][Ni(HN₂S₂)(N₂S₂)] was determined by X-ray structure analysis.     

O2 和 CO 在 Co2B2/TiO2 和 Co2B2Pt/TiO2 表面吸附的密度泛函研究

 采用密度泛函理论探讨了 TiO2 表面负载 Co2B2 和 Co2B2Pt 合金簇可能的负载构型. 结果表明, Co2B2 和 Co2B2Pt 合金簇倾向于以两个 Co 的形式负载在两个氧上. 态密度分析发现, 负载后, Co2B2 合金簇中部分 Co 原子和 B 原子成键加强, Co2B2Pt 合金簇中 Pt 原子和 B 原子成键也加强, 形成新的轨道. CO 和 O2 在 Co2B2/TiO2 和 Co2B2Pt/TiO2 表面吸附的结果表明, Co2B2Pt/TiO2 催化氧化 CO 性能的提高是由于 Pt 原子提高了 Co2B2 合金簇吸附 CO 和 O2 的能力.     

The bivalent metal hypophosphites Sr(H2PO2)2, Pb(H2PO2)2 and Ba(H2PO2)2

The structures of isomorphous monoclinic strontium and lead bis­(di­hydrogenphosphate), Sr(H₂PO₂)₂ and Pb(H₂PO₂)₂, and orthorhombic barium bis­(di­hydrogen­phos­phate), Ba(H₂PO₂)₂, consist of layers of hypophosphite anions and metal cations exhibiting square antiprismatic coordination by O atoms. The Sr and Pb atoms are located on sites with point symmetry 2, and the Ba atoms are on sites with point symmetry 222. Within the layers, each anion bridges four metal cations.     

Neue Verbindungen mit SrNi2V2O8-Struktur: BaCo2V2O8 und BaMg2V2O8

New Compounds of the SrNi₂V₂O₈-Type: BaCo₂V₂O₈ and BaMg₂V₂O₈ For the first time BaCo₂V₂O₈ (A) and BaMg₂V₂O₈ (B) were prepared and investigated by X-ray methods. Space group: D–I4₁/acd, Z = 8. ((A): a = 12.4441, c = 8.4153 Å; (B): a = 12.4189, c = 8.4657 Å). A and B crystallize with higher symmetry, but they are isotypic with SrNi₂V₂O₈. The differences in crystal chemistry in respect to the BaNi₂V₂O₈-type are discussed.     

Kinetics and products of chlorine atom initiated oxidation of HCF2OCF2OCF2CF2OCF2H and HCF2O(CF2O)n‐(CF2CF2O)mCF2H

Smog chamber/FTIR techniques were used to measure k(Cl + HCF₂OCF₂OCF₂‐CF₂OCF₂H) = k(Cl + HCF₂O(CF₂O)_n(CF₂CF₂O)_mCF₂H) = (5.0 ± 1.4) × 10^?17 cm³ molecule^?1 s^?1 in 700 Torr of N₂/O₂ diluent at 296 ± 1 K. The Cl‐initiated atmospheric oxidation of HCF₂OCF₂OCF₂CF₂OCF₂H and the sample of HCF₂O(CF₂O)_n(CF₂CF₂O)_mCF₂H used in this work gave COF₂ in molar yields of (476 ± 36)% and (859 ± 63)%, respectively, with no other observable carbon containing products (i.e., essentially complete conversion of both hydrofluoropolyethers into COF₂). The results are discussed with respect to the atmospheric chemistry and environmental impact of hydrofluoropolyethers of the general formula HCF₂O(CF₂O)_n(CF₂CF₂O)_mCF₂H. © 2008 Wiley Periodicals, Inc. Int J Chem Kinet 40: 819–825, 2008     

Synthesis and crystal structure of [Nb2(S1.72Se2.28)(S2CNEt2)4]—A solid solution based on [Nb2(μ2, η2-X2)2(S2CNEt2)4], where X2=S2, SSe,and Se2. New model of structure refinement of [Nb2(S2)2(S2CNEt2)4], where X2=S2, SSe,and Se2. New model of structure refinement of [Nb2(S2)2(S2CNEt2)4]

The crystal structure of [Nb₂(S_1.72Se_2.28)(S₂CNEt₂)₄], which is a solid solution based on [Nb₂(μ₂, η²-X₂)₂(S₂CNEt₂)₄], where X₂=S₂, SSe, and Se₂, is determined. The compound was obtained by the reaction of NaS₂CNEt₂ in CH₃CN with the product of the reaction of the NbSe₂Cl₂-KNCS fusion cake with an aqueous solution of Bu₄NBr (yield 30%). The crystals are monoclinic, a=21.319(11), b=7.008(1), c=16.673(8) Å, β=133.99(2)°, V_cell=1792(1) ų, space group C2/m, Z=2, d_calc=1.879 g/cm³ for C₂₀H₄₀N₄Nb₂S_9.72Se_2.28, Syntex P2₁, λCukα, N_meas/corr=2423/1191, R(F)=0.0569 and wR(F²)=0.1282 for 889 F_hkl>4σ(F). The compound is isostructural to the thio analog Nb₂S₄(S₂CNEt₂)₄ studied earlier; in both cases, the molecule is disordered in crystals over two positions. The composition was refined by diffraction data. The results are in good agreement with the Raman and FMB (fast molecule bombardment) mass spectrometry data. The structure of Nb₂S₄(S₂CNEt₂)₄ was refined for the second time using a new model of disorder; as a result of the refinement, a normal value of S?S bond length in the S₂ ligand [2.027(5) Å] was obtained.