Solid State Chemistry of A4B3−Molecules

Abstract

The system P₄S₃?P₄Se₃?As₄S₃?As₄Se₃ was investigated by thermal and X-ray methods. Five regions of solid solubility with different crystal structures were found. All transform at higher temperatures into the plastically-crystalline state with β-P₄S₃?structure.

The substituted species P_4-nAs_nS_mSe_3-m (n = 0–4, m = 0–3) are formed in molten mixtures of A₄B₃?molecules (FIGURE 1). They were identified by HPLC and mass-spectrometric measurements.

After long equilibration times P₄Se₃, As₄S₃ and As₄Se₃ decompose peritectoidally into the resp. A₄B₄?species and an amorphous product.     

Neue Moleküle A4B3 im System P4Se3–As4Se3

Novel A₄B₃ Molecules in the System P₄Se₃–As₄Se₃ By means of ³¹P-NMR and masspectroscopic measurements in the system P₄Se₃–As₄Se₃ was shown that in the melt and vapour phase at all compositions molecules of the type P_{4 ? n}As_nSe₃ are formed. A separation was possible by liquid chromatography (RP 18-column). The concentration distribution of the different species is nearly statistical. In the solid state at ambient temperature regions of solid solubility with α-P₄Se₃, α⁺-phase, α-P₄S₃ and α-As₄Se₃ structure were observed. P₃AsSe₃ could be transformed into a plastically-crystalline phase with β-P₄S₃ structure. At higher temperatures the phase decomposes slowly. The thermal behaviour of PAs₃Se₃ is strongly influenced by the heating rate. Using low heating rates it decomposes into an amorphous phase, by fast heating a transformation into a metastable plastically-crystalline modification was achieved. During long extraction with CS₂ molecules P_{4 ? n}As_nS_{3 ? m}Se_m are formed by an exchange reaction. They can also be prepared by melting the proper amounts of the elements.     

Konzentrationen von Isomeren des Typs P m As4−m X 3 in P4S3-As4S3- und P4Se3-As4Se3-Mischungen

The reactions of P₄S₃ with As₄S₃ and of P₄Se₃ with As₄Se₃ in the molten state yields molecules of the type P _m As_4–m S₃ and P _m As_4–m Se₃, respectively. A method was developed to separate the different components by the HPLC technique, and to determine their concentrations. The identification of the isomers in the HPLC pattern was achieved with the aid of the LC-MS method. In the selenium system, the distribution of the different species is statistical. In the system P₄S₃-As₄S₃, the formation of PAs₃S₃ with one phosphorus atom in the apical position is favoured.

     

Züchtung und Untersuchung von Einkristallen in den pseudobinären Systemen ABS2?SnS2 (A = Cu,Ag; B = Al,Cr)

Preparation and Characterization of Single Crystals in the Pseudo-binary Systems ABS₂? SnS₂ (A = Cu, Ag; B = Al, Cr) In the pseudo-binary systems ABS₂? SnS₂ (A = Cu, Ag; B = Al, Cr) single crystals were grown by chemical transport using AlCl₃/I₃ mixtures as transporting agents. Characterization of the crystals was done by electron microprobe analyses and X-ray methods. The composition A_1?x□_x[B_1?xSb_1+x]S₄ was found for the non-stoichiometric phases. The compounds are normal spinels, the space group is Fd3m. The results of least squares refinement using single crystal X-ray data are reported.     

Character of interaction and glass formation in the TlAs<Subscript>2</Subscript>Se<Subscript>4</Subscript>-Tl<Subscript>3</Subscript>As<Subscript>2</Subscript>S<Subscript>3</Subscript>Se<Subscript>3</Subscript> system

The TlAs₂Se₄-Tl₃As₂S₃Se₃ system was investigated by physicochemical methods (DTA, X-ray powder diffraction, microstructural analysis), and its phase diagram was constructed. The TlAs₂Se₄-Tl₃As₂S₃Se₃ join is a quasi-binary internal section of the As-Tl-S-Se quaternary system. The solubility range of TlAs₂Se₄-based solid solutions is extended to 7 mol %, and the region of Tl₃As₂S₃Se₃-based solid solutions is extended to 15 mol %.     

Zur Kenntnis des quaternären Systems Zn?In?S?Se Der Schnitt ZnIn2S4?Znln2Se4?In2S3?In2Se3

The Quaternary System ZnIn₂S₄? ZnIn₂Se₄? In₂Se₃? In₂S₃ The title system has been investigated on the indium rich side (ratio In/Zn ≥ 2) on samples quenched from 800°C to room temperature using x-ray methods. In this section 7 different phases could be identified the phase borders of which are given. ZnIn₂S₄-type and thiogallate type mixed crystals only show a small region of homogeneity while the monophase region of spinel type mixed crystals in the indiumsulfide rich part of the phase diagram has a larger extension. There is a new trigonal compound ZnIn₂S₂Se₂ (a_hex = 3.937, c_hex = 31.97 Å) with a large region of homogeneity. In the indiumselenide rich part there are two new phases: (i) Zn_0.4In₂Se_3.4 with unknown structure and (ii) a ternary phase of unknown structure in the system In₂S_3?xSe_x for 2.1 ≤ x ≤ 2.7.     

Die Systeme Arsen-Schwefel und Arsen-Selen und die thermodynamischen Daten ihrer Verbindungen

The Systems Arsenic-Sulphur and Arsenic-Selenium and the Thermodynamical Data of their Compounds The phase diagrams As? S and As? Se were determined by differential scanning calorimetry. The cage molecules As₄S₃ and probably As₄S₃ were found in the equilibrium systems. The different modifications of As₄S₄, As₄S₃, and As₄Se₃ were investigated by DSC and high temperatur X-ray methods. The transition β → β- As₄S₄ is reversible with extrem slow cooling rates. β- As₄S₃ transform to β- As₄S₃ at 404 K. The plastic phase of all A₄B₃ cages is probably of tetragonal symmetry. At still higher temperatures the melt of As₄S₃ resp. solid As₄S₃ polymerizes. The thermodynamic data – C_p, ΔHu, ΔHm – of the compounds in the system As? S and As? Se were determined.     

Synthese und Kristallstruktur von ACu4As2 (A: Ca–Ba,Eu)

Synthesis and Crystal Structure of A Cu₄As₂ ( A : Ca–Ba, Eu) Steel‐gray single crystals of ACu₄As₂ with A = Ca–Ba and Eu respectively were synthesized by heating mixtures of the elements at about 900 °C. Structure determinations with X‐ray diffractometry data revealed, that the isotypic compounds crystallize in the rhombohedral CaCu₄P₂ type structure (R3m; Z = 3) (hexagonal axes see ”︁Inhaltsübersicht”︁”︁). Measurements of the susceptibility of EuCu₄As₂ showed divalent Eu and ferromagnetic order at 35 K.     

Na2B2Se7, K2B2S7 und K2B2Se7: Drei Perchalkogenoborate mit neuem polymeren Anionengerüst

Na₂B₂Se₇, K₂B₂S₇, and K₂B₂Se₇: Three Perchalcogenoborates with a Novel Polymeric Anion Network Na₂B₂Se₇ (I 2/a; a = 11.863(4) Å, b = 6.703(2) Å, c = 13.811(6) Å, β = 109.41(2)°; Z = 4), K₂B₂S₇ (I 2/a; a = 11.660(2) Å, β = 6.827(1) Å, c = 12.992(3) Å, β = 106.78(3)°; Z = 4), and K₂B₂Se₇ (I 2/a; a = 12.092(4) Å, b = 7.054(2) Å, c = 13.991(5) Å, β = 107.79(3)°; Z = 4) were prepared by reaction of stoichiometric amounts of sodium selenide (potassium sulfide) with boron and sulfur or of potassium selenide and boron diselenide, respectively, at 600°C with subsequent annealing. The crystal structures consist of polymeric anion chains of composition ([B₂S₇]^2?)_n or ([B₂Se₇]^2?)_n formed by spirocyclically connected five-membered B₂S₃ (B₂Se₃) rings and six-membered B₂S₄ (B₂Se₄) rings. The nine-coordinate alkaline metal cations are situated in between.     

Synthesis,Crystal Structure,and Vibrational Spectroscopy of the Alkali Diselenates A2Se2O7 (A = Li – Cs)

The reaction of alkali carbonates and selenium acid yielded the “pyroanions” [Se₂O₇]^2– containing alkali diselenates. By varying the alkali carbonates we were able to synthesize and determinate the crystal structures of the whole row from Li to Cs. Li₂Se₂O₇ crystallizes isotypic to Li₂S₂O₇ [Pnma, Z = 4, a = 13.815(3), b = 8.452(2) c = 5.0585(10) Å]. The structure of Na₂Se₂O₇ [P$\bar{1}$ , Z = 2, a = 6.9896(14), b = 6.9938(14), c = 7.0829(14) Å, α = 83.32(3), β = 64.56(3), γ = 83.18(3)°] is isotypic to Ag₂S₂O₇. A₂Se₂O₇ (A = K, Rb) [A = K: C2/c, Z = 4, a = 12.851(3), b = 7.5677(15), c = 7.5677(15) Å, β = 93.35(3)°; A = Rb: C2/c, Z = 4, a = 13.118(3), b = 7.7963(16), c = 7.7811(16) Å, β = 94.03(3)°] are isotypic to K₂S₂O₇. The crystal structure of Cs₂Se₂O₇ [P$\bar{1}$ , Z = 10, a = 7.7271(3), b = 16.2408(8), c = 18.4427(8) Å, α = 89.685(2), β = 89.193(2), γ = 76.251(2)°] seems to be isotypic to the averaged room‐temperature modification of Cs₂S₂O₇. With exception of the caesium compound all diselenate anions show an ecliptic arrangement and can be therefore classified as dichromate‐like structures. In Cs₂Se₂O₇ most of the [Se₂O₇]^2– units have a staggered alignment. The transition between both orientations can be explained by the increase of the cations size. Additionally the vibrational spectra of A₂Se₂O₇ with A = Li – Cs are discussed as well as the resulting bond forces.     

Thermoanalysis of quasi-ternary As2(S,Se, Te)3 semiconductor glasses

In comparison with other chalcogenide glassy systems, less attention has been paid to the quasi-ternary (quaternary) system As₂(S, Se, Te)₃. In this paper, thermal methods were used to characterize ten different quaternary homogenous semiconductor glasses that were prepared by mixing the stoichiometric binary systems As₂S₃, As₂Se₃ and As₂Te₃. The ratios of the constituent binaries in the quasi-ternary glasses exerted a great influence on their thermal spectrum. The samples poor in As₂Te₃ showed neither the exothermic nor the endothermic peak due to crystallízation (T _c) and melting (T _m), respectively, but only the glass transition (T _g). Three transition temperatures,T _g, T_c andT _m, were detected for other compositions. On the other hand, a phase separation was observed in the samples rich in As₂Te₃. A cyclic scanning technique was used to investigate the thermally-induced phases during two consecutive heat ing-cooling cycles covering the temperature rangeT _g?T_m. The energy of decompositionE _d decreased on increase of the ratio As₂S₃/As₂Se₃ (at constant As₂Te₃), whereas it increased on increase of the ratio As₂Te₃/As₂Se₃ (at constant As₂Se₃ or As₂S₃).     

Laser Desorption Ionization of As<Subscript>2</Subscript>Ch<Subscript>3</Subscript> (Ch = S,Se, and Te) Chalcogenides Using Quadrupole Ion Trap Time-of-Flight Mass Spectrometry: A Comparative Study

Laser desorption ionization using time-of-flight mass spectrometer afforded with quadrupole ion trap was used to study As₂Ch₃ (Ch = S, Se, and Te) bulk chalcogenide materials. The main goal of the study is the identification of species present in the plasma originating from the interaction of laser pulses with solid state material. The generated clusters in both positive and negative ion mode are identified as 10 unary (S _p ^+/– and As _m ^+/– ) and 34 binary (As _m S _p ^+/– ) species for As₂S₃ glass, 2 unary (Se _q ^+/– ) and 26 binary (As _m Se _q ^+/– ) species for As₂Se₃ glass, 7 unary (Te _r ^+/– ) and 23 binary (As _m Te _r ^+/– ) species for As₂Te₃ material. The fragmentation of chalcogenide materials was diminished using some polymers and in this way 45 new, higher mass clusters have been detected. This novel approach opens a new possibility for laser desorption ionization mass spectrometry analysis of chalcogenides as well as other materials.

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Phosphorus and Arsenic Chalcogenides as Reagents Toward Transition Metal-Ligand Systems

Abstract

The compounds obtained by reacting the P₄S₃, P₄Se₃ and As₄S₃ cage molecules with various transition metal-ligand moieties are reported. The transition metal-ligand systems are bound either to the intact molecules or to fragments (hexa- or tri-atomic) originating from the cage molecules. Such compounds provide examples of selective activation of cage molecules by metal moieties.     

Syntheses and Crystal Structures of Rb2B2Se7, Tl2B2Se7, Cs3B3Se10, and Tl3B3Se10: New Perseleno‐selenoborates with Polymeric Anionic Chains

The perseleno‐selenoborates Rb₂B₂Se₇ and Cs₃B₃Se₁₀ were prepared from the metal selenides, amorphous boron and selenium, the thallium perseleno‐selenoborates Tl₂B₂Se₇ and Tl₃B₃Se₁₀ directly from the elements in evacuated carbon coated silica tubes by solid state reactions at temperatures between 920 K and 950 K. All structures were refined from single crystal X‐ray diffraction data. The isotypic perseleno‐selenoborates Rb₂B₂Se₇ and Tl₂B₂Se₇ crystallize in the monoclinic space group I 2/a (No. 15) with lattice parameters a = 12.414(3) Å, b = 7.314(2) Å, c = 14.092(3) Å, β = 107.30(3)°, and Z = 4 for Rb₂B₂Se₇ and a = 11.878(2) Å, b = 7.091(2) Å, c = 13.998(3) Å, β = 108.37(3)° with Z = 4 for Tl₂B₂Se₇. The isotypic perseleno‐selenoborates Cs₃B₃Se₁₀ and Tl₃B₃Se₁₀ crystallize in the triclinic space group P1 (Cs₃B₃Se₁₀: a = 7.583(2) Å, b = 8.464(2) Å, c = 15.276(3) Å, α = 107.03(3)°, β = 89.29(3)°, γ = 101.19(3)°, Z = 2, (non‐conventional setting); Tl₃B₃Se₁₀: a = 7.099(2) Å, b = 8.072(2) Å, c = 14.545(3) Å, α = 105.24(3)°, β = 95.82(3)°, γ = 92.79(3)°, and Z = 2). All crystal structures contain polymeric anionic chains of composition ([B₂Se₇]^2–)_n or ([B₃Se₁₀]^3–)_n formed by spirocyclically fused non‐planar five‐membered B₂Se₃ rings and six‐membered B₂Se₄ rings in a molar ratio of 1 : 1 or 2 : 1, respectively. All boron atoms have tetrahedral coordination with corner‐sharing BSe₄ tetrahedra additionally connected via Se–Se bridges. The cations are situated between three polymeric anionic chains leading to a nine‐fold coordination of the rubidium and thallium cations by selenium in M₂B₂Se₇ (M = Rb, Tl). Coordination numbers of Cs⁺ (Tl⁺) in Cs₃B₃Se₁₀ (Tl₃B₃Se₁₀) are 12(11) and 11(9).     

Li6+2x[B10Se18]Sex (x ≈ 2), ein ionenleitendes Doppelsalz

Li_6+2x[B₁₀Se₁₈]Se_x (x ≈ 2), an Ion‐conducting Double Salt Li_6+2x[B₁₀Se₁₈]Se_x (x ≈ 2) was prepared in a solid state reaction from lithium selenide, amorphous boron and selenium in evacuated carbon coated silica tubes at a temperature of 800 °C. Subsequent cooling from 600 °C to 300 °C gave amber colored crystals with the following lattice parameters: space group I2/a (at 173 K); a = 17.411(1) Å, b = 21.900(1) Å, c = 17.820(1) Å, β = 101.6(1)°. The crystal structure contains a well‐defined polymeric selenoborate network of composition ([B₁₀Se₁₆Se_4/2]^6?)_n consisting of a system of edge‐sharing [B₁₀Se₁₆Se_4/2] adamantanoid macro‐tetrahedra forming large channels in which a strongly disorderd system of partial occupied Li⁺ cations and additional disordered Se^2? anions is observed. The crystal structure of the novel selenoborate is isotypic to Li_6+2x[B₁₀S₁₈]S_x (x ≈ 2) [1]. X‐ray and ⁷Li magic‐angle spinning NMR data suggest that the site occupancies of the three crystallographically distinct lithium ions exhibit a significant temperature dependence. The lithium ion mobility has been characterized by detailed temperature dependent NMR lineshape and spin‐lattice relaxation measurements.     

Die Undecaarsenide A3As11 (A = Rb,Cs) — Synthesen und Kristallstrukturen

Alkaline Metal Arsenides A₃As₁₁ (A = Rb, Cs): Preparation and Crystal Structures Rb₃As₁₁ and Cs₃As₁₁ were synthesized from the elements and the crystal structures of the ordered room temperature form were characterized via single crystal x‐ray studies. In the Zintl phases the As atoms form chiral ufosan‐anions As with As‐As distances ranging from 238 to 248 pm. Like K₃As₁₁ Rb₃As₁₁ crystallizes with the Na₃P₁₁ structure type (orthorhombic, space group Pbcn, a = 1108.2(2), b = 1533.5(3), c = 1060.1(2) pm, Z = 4), whereas the Cs compound (monoclinic, space group C2/c, a = 1324.5(7), b = 1524.5(9), c = 1937.2(11) pm, β = 95.29(1)°, Z = 8) forms a new structure type. The crystallographic relationship between the two structure types and the anion packings in the plastic crystalline high temperature forms are discussed.     

As12Se44—: ein neuartiges Selenoarsenatanion mit einem Polyarsenkäfig in der Verbindung [Co(NH3)6]2As12Se4 · 12 NH3

As₁₂Se₄^4—: a New Selenoarsenate Anion with a Polyarsenic Cage in the Compound [Co(NH₃)₆]₂As₁₂Se₄ · 12 NH₃ Orange coloured crystals of [Co(NH₃)₆]₂As₁₂Se₄ · 12 NH₃ were prepared by the reduction of As₄Se₄ with a solution of sodium in liquid ammonia and subsequent precipitation with CoBr₂. The X‐ray structure determination shows them to contain the selenoarsenate anion As₁₂Se₄^4—, which consists of a central As₁₂‐cage with four exo‐bonded, formally negatively charged Se atoms. The structure of the As₁₂‐cage is equivalent to the main polyphosphorus building unit of a known organopolyphosphane and of tubular P₁₂ in the compound (CuI)₃P₁₂.     

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.     

Schwingungsspektren von As4S4 und As4Se4

Vibrational Spectra of As₄S₄ and As₄Se₄ The vibrational spectra of solid α- and β-As₄S₄ and the Raman spectrum of molten As₄S₄ have been recorded. The assignments of the frequencies are proposed mainly based on polarization data. The Raman melt spectra suggest that As₄S₄ molecules (symmetry D_2d) are retained in the molten state. A partial decomposition of the melt by prolonged laser irradiation was observed. The Raman spectrum of solid As₄Se₄ is presented and the frequencies are tentatively assigned to an As₄Se₄ molecule of the cradle type, possessing D_2d symmetry.