Zur Neuuntersuchung des Phasendiagramms InI—SnI2

Redetermination of the Phase Diagram InI—SnI₂ The phase diagram of the system InI—SnI₂ was redetermined with DTA and X-ray methods. We found that the compound given in the literature by the formula In₄SnI₆ is not formed. Instead of this a phase with lower InI content and having the composition In₃SnI₅ could be established, which crystallizes in three different low temperature polymorphs. This compound transforms to yet another, high temperature polymorph to 247^°C. Additionally a ternary compound with the formula Insn₂I₅ could be observed in the system InI—SnI₂, which has the tetragonal NH₄Pb₂Br₅ structure.     

Ternäre Thallium-Indium-Sulfide: Eine Zusammenfassung

Ternary Thallium Indium Sulfides: A Summary Combined thermal and X-Ray analyses in the ternary system Thallium—Indium—Sulfur show, that the two binary sections Tl₂S? In₂S₃ and TlS? InS contain ternary compounds with unique crystal structures. The chemical formulas of these ternary solids are TlIn₅S₈, TlIn₃S₅, TlInS₂ and Tl₃InS₃ for the section Tl₂S? In₂S₃ and TlIn₅S₆ as well as Tl₃In₅S₈ (metastable high temperature phase) for the section TlS? InS respectively. With TlIn₅S₇ an additional ternary solid could be detected, which is located outside the two sections. It is derived from the binary mixed valence compound In₆S₇ by complete substitution of In⁺ by Tl⁺. The following ionic formulations make the mixed valence character of the ternary Thallium—Indium-Sulfides reasonable: TlIn₅S₈ = Tl⁺(In³⁺)₅(S^2?)₈, TlIn₃S₅ = Tl⁺ (In³⁺)₃(S^2?)₅, TlInS₂ = Tl⁺In³⁺(S^2?)₂, Tl₃InS₃ = (Tl⁺)₃In³⁺ · (S^2?)₃, TlIn₅S₆ = Tl⁺([In₂]⁴⁺)₂In³⁺ (S^2?)₆, Tl₃In₅S₈ = 4 × [(Tl⁺)_0,75 · (In⁺)_0,25In³⁺(S^2?)₂], TlIn₅S₇ = Tl⁺[In₂]⁴⁺ (In³⁺)₃(S^2?)₇. All compounds contain Tl⁺-ions in a characteristic “lone pair coordination” of S^2? ions. Indium atoms however occur with the oxidation numbers +2 (formal, In₂ dumb bells with covalent In? In bonding) and +3 (with In³⁺ in tetrahedral and octahedral coordination of S^2?). Chemical preparation, crystal chemistry and general properties of the ternary solids are discussed, summarized and compared to each other.     

Synthese und Strukturuntersuchungen von Iodocupraten (I). XI. Die Kristallstruktur von Tl4Cu2I6

Syntheses and Structure Analyses of Iodocuprates (I). XI. Crystal Structure of Tl₄Cu₂I₆ Tl₄Cu₂I₆ was prepared by melting TlI and CuI or by hydrothermal synthesis in concentratet aqueous HI solution. The crystal structure analysis of Tl₄Cu₂I₆ (orthorhombic, Pnnm, a = 919.6(1), b = 955.2(2), c = 933.6(2) pm, Z = 2) shows that the compound contains dinuclear anions [Cu₂I₆]^4? which are built up by edge sharing CuI₄-tetrahedra. The coordination of Tl^I with I^? is analogous to the yellow TlI.     

Phase diagram of the Tl-TlI-S system and thermodynamic properties of the compound Tl<Subscript>6</Subscript>SI<Subscript>4</Subscript>

Phase equilibria in the Tl-TlI-S composition region of the Tl-S-I system were studied by differential thermal analysis, x-ray powder diffraction, and measurements of the microhardness and the emf of concentration circuits relative to a thallium electrode. A series of polythermal sections, an isothermal section at 300 K, and a projection of the liquidus surface were constructed. Primary crystallization regions of six phases, including the ternary compounds Tl₆SI₄ and Tl₃SI, were outlined, and the types and coordinates of non- and monovariant equilibria were determined. It was shown that the ternary compound Tl₆SI₄ forms tie lines with Tl, TlI, Tl₂S, Tl₄S₃, and TlS in the subsolidus region and that the homogeneity region of Tl₆SI₄ below 400 K does not exceed 1 mol %. From the emf measurement data, the standard thermodynamic functions of formation and standard entropy of the compound Tl₆SI₄ were calculated: G _f,298⁰ = −601.7 ± 2.5 kJ/mol, ΔH _f,298⁰= −595.1 ± 4.0 kJ/mol, and S ₂₉₈⁰ = 672 ± 10 J/(mol K).     

Thallium alloys of the rare earth: Sm?TI Phase diagram and molar volumes of the rare earth thallides

The Sm? Tl system has been studied by differential thermal, metallographic and X-ray analyses. The following intermediate phases were observed: Sm₂Tl (decomposes at 1030 ± 10°C); Sm₅Tl₃ (decomposes at 1060 ± 10°C); SmTl (melting point, 1220 ± 20°C); Sm₃Tl₅ (decomposes at 940 ± 10°C); SmTl₃ (melting point, 870 ± 5°C). Three eutectics occur: β-Sm—Sm₂Tl (840 ± 10°C, 18.0 ± 0.5 at % Tl); Sm₃Tl₅—SmTl₃ (860 ± 5°C, 72.0 ± 0.5 at % Tl); SmTl₃—β-Tl (～303°C, greater than 99.5 at % Tl); there is an eutectoidal reaction at 760 ± 10°C and 10 ± 1 at % Tl (decomposition of β-Sm phase). Following crystal structures have been determined or confirmed: Sm₂Tl hexagonal hP6—Ni₂In-type, Sm₅Tl₃ tetragonal tI32—W₅Si₃-type, SmTl cubic cI2—W or cP2—CsCl-type, SmTl tetragonal tP4—AuCu I-type, Sm₃Tl₅ orthorhombic oC32—Pu₃Pd₅ like-type, SmTl₃ cubic cP4—AuCu₃-type. The characteristics of the phase diagram and the molar volumes of the Sm? Tl compounds are compared with those of other RE? Tl alloys and briefly discussed.     

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.     

Schwache Sn…I‐Wechselwirkungen in den Kristallstrukturen der Iodostannate [SnI4]2– und [SnI3]–

Weak Sn…I Interactions in the Crystal Structures of the Iodostannates [SnI₄]^2– and [SnI₃]^– Iodostannate complexes can be crystallized from SnI₂ solutions in polar organic solvents by precipitation with large counterions. Thereby isolated anions as well as one, two or three‐dimensional polymeric anionic substructures are established, in which SnI₃^– and SnI₄^2– groups are linked by weak Sn…I interactions. Examples are the iodostannates [Me₃N–(CH₂)₂–NMe₃][SnI₄] ( 1 ), (Ph₄P)₂[Sn₂I₆] ( 2 ), [Me₃N–(CH₂)₂–NMe₃][Sn₂I₆] ( 3 ), [Fe(dmf)₆][SnI₃]₂ ( 4 ) and (Pr₄N)[SnI₃] ( 5 ), which have been characterized by single crystal X‐ray diffraction. [Me₃N–(CH₂)₂–NMe₃][SnI₄] ( 1 ): a = 671.6(2), b = 1373.3(4), c = 2046.6(9) pm, V = 1887.7(11) · 10⁶ pm³, space group Pbcm;(Ph₄P)₂[Sn₂I₆] ( 2 ): a = 1168.05(6), b = 717.06(4), c = 3093.40(10) pm, β = 101.202(4)°, V = 2541.6(2) · 10⁶ pm³, space group P2₁/n;[Me₃N–(CH₂)₂–NMe₃][Sn₂I₆] ( 3 ): a = 695.58(4), b = 1748.30(8), c = 987.12(5) pm, β = 92.789(6)°, V = 1199.00(11) · 10⁶ pm³, space group P2₁/c;[Fe(dmf)₆][SnI₃]₂ ( 4 ): a = 884.99(8), b = 1019.04(8), c = 1218.20(8) pm, α = 92.715(7), β = 105.826(7), γ = 98.241(7), V = 1041.7(1) · 10⁶ pm³, space group P1;(Pr₄N)[SnI₃] ( 5 ): a = 912.6(2), b = 1205.1(2), c = 1885.4(3) pm, V = 2073.5(7) · 10⁶ pm³, space group P2₁2₁2₁.     

Darstellung,Eigenschaften, röntgenographische und spektroskopische Untersuchung von Tl4Nb2S11 und Tl4Ta2S11

On Polychalcogenides of Thallium with M₂Q₁₁ Groups as a Structural Building Block. I Preparation, Properties, X‐ray Diffractometry, and Spectroscopic Investigations of Tl₄Nb₂S₁₁ and Tl₄Ta₂S₁₁ The new ternary compounds Tl₄Nb₂S₁₁ and Tl₄Ta₂S₁₁ were prepared using Thallium polysulfide melts. Tl₄M₂S₁₁ crystallises isotypically to K₄Nb₂S_8.9Se_2.1 in the triclinic space group P 1 with a = 7.806(2) Å, b = 8.866(2) Å, c = 13.121(3) Å, α = 72.72(2)°, β = 88.80(3)°, and γ = 85.86(2)° for M = Nb and a = 7.837(1) Å, b = 8.902(1) Å, c = 13.176(1) Å, α = 72.69(1)°, β = 88.74(1)°, and γ = 85.67(1)° for M = Ta. The interatomic distances as well as angles within the [M₂S₁₁]^4– anions are similar to those of the previously reported data for analogous alkali metal polysulfides. Significant differences between Tl₄M₂S₁₁ and A₄M₂S₁₁ (A = K, Rb, Cs) are obvious for the shape of the polyhedra around the electropositive elements. The two title compounds melt congruently at 732 K (M = Nb) and 729 K (M = Ta). The optical band gaps were estimated as 1.26 eV for Tl₄Nb₂S₁₁ and as 1.80 eV for the Tantalum compound.     

Probing the Reactivity of the Potent AgF2 Oxidizer. Part 2: Inorganic Compounds

The reactivity of Ag^IIF₂ towards forty two inorganic compounds containing oxo‐ and chloro‐ ligands, has been investigated. Five families of compounds were studied: (i) binary oxides of metals and nonmetals, (ii) ternary salts of inorganic oxo acids, (iii) concentrated or anhydrous oxo‐ acids, (iv) binary and ternary chlorides and (v) oxochlorides. At low temperatures up to 200 °C AgF₂ readily oxidizes HgO, B₂O₃, PbO₂, As₂O₅, Ag₂SO₄, LiBO₂, K₂CO₃, KVO₃, Ag₂WO₄, and AgMnO₄ with concomitant oxygen evolution. In the same conditions V₂O₅, CrO₃, MoO₃, WO₃, CuO, Tl₂O₃, I₂O₅, Re₂O₇, K₂SO₄, HgSO₄, KSO₃F, KNO₃, KClO₄, KIO₄, BaCrO₄, KMnO₄ and KReO₄ resist the action of AgF₂ but many of these compounds get oxidized at higher temperatures (up to nearly 300 °C). Substantial inertness of sulfates, chromates, nitrates, perchlorates, permanganates and perrhenates suggests that one might attempt to synthesize salts of divalent silver with these anions. AgF₂ vigorously reacts with H₂SO₄ (fuming, 30% SO₃), HSO₃Cl (100%), HClO₄ (70%), and HNO₃ (fuming, 100%) at room temperature yielding salts of Ag^I and O₂; for HClO₄ and HNO₃ pre‐cooled to ?35 °C metastable perchlorate / nitrate complexes of Ag^II are obtained. Anhydrous HSO₃F behaves similar to HSO₃CF₃ (see Part 1 of this series) yielding slow methathetical conversion of AgF₂ without concomitant redox reaction. Majority of chlorides and oxochlorides studied (AgCl, AuCl₃, KAuCl₄, WCl₆, WOCl₄, MoOCl₄, MoO₂Cl₂) react with AgF₂ at temperatures below 160 °C. Reaction with SiCl₄ (in contrast to CCl₄) is violent and very exothermic at room temperature. Liquid CrO₂Cl₂ (at room temperature) and solid WO₂Cl₂ (up to 180 °C) are kinetically inert to AgF₂. We do not observe intercalation of AgF₂ with various redox—inert oxo‐ and chloro‐ Lewis bases at the experimental conditions.     

Mixed‐Valence Thallium(I,III) Bromides The Crystal Structure of α—Tl2Br3

Thallium sesquibromide Tl₂Br₃ is dimorphic. Scarlet coloured crystals of α‐Tl₂Br₃ were obtained by reactions of aqueous solutions of TlBr₃ and Tl₂SO₄ in agarose gel. In case of rapid crystallisation of hydrous TlBr₃/TlBr solutions and from TlBr/TlBr₂ melts ß‐Tl₂Br₃ is formed as scarlet coloured, extremely thin lamellae. The crystal structures of both forms are very similar and can be described as mixed‐valence thallium(I)‐hexabromothallates(III) Tl₃[TlBr₆]. In the monoclinic unit cell of α‐Tl₃[TlBr₆] (a = 26.763(7) Å; b = 15.311(6) Å; c = 27.375(6) Å; β = 108.63(2)°, Z = 32, space gr. C2/c) the 32 Tl^III‐cations are found in strongly distorted octahedral TlBr₆ groups. The 96 Tl^I cations are surrounded either by four or six TlBr₆ groups with contacts to 8 or 9 Br neighbors. Crystals of β‐Tl₃[TlBr₆] by contrast show almost hexagonal metrics (a = 13.124(4) Å, b = 13.130(4) Å, c = 25.550(7) Å, γ = 119.91(9)°, Z = 12, P2₁/m). Refinements of the parameters revealed structural disorder of TlBr₆ units, possibly resulting from multiple twinning. Both structures are composed of Tl₂[TlBr₆]^— and Tl₄[TlBr₆]⁺ multilayers, which alternate parallel (001). The structural relationships of the complicated structures of α‐ and β‐Tl₃[TlBr₆] to the three polymorphous forms of Tl₂Cl₃ as well as to the structures of monoclinic hexachlorothallates M₃TlCl₆ (M = K, Rb) and the cubic elpasolites are discussed.     

Über Chalkogenidhalogenide des Kupfers

Nine ternary chalcogenidehalides of copper could be synthesized under hydrothermal conditions from the resp. hydrogen halide solutions. They belong to the pseudobinary systems, formed between selenium and tellurium and the resp. Cu^I halide. In the selenium systems exist: CuISe₃, rhombohedral; CuBrSe₃, orthorhombic, and CuClSe₂, monoclinic. Two homologous series of tellurium compounds exist: CuXTe, tetragonal, and CuXTe₂, monoclinic (X ? Cl, Br, I). Thermodynamic data could be obtained for the selenium compounds using the Knudsen effusion method. The samples exhibit a temperature independant diamagnetism. All compounds can also be synthesized by reaction of stoichiometric amounts of Cu^I halide and selenium (300°C) or tellurium (350°C). The corresponding thiohalides could not be observed.     

Preparation,Crystal Structure,Physical Properties,and Electronic Band Structure of TlTaS3

TlTaS₃ was prepared by applying a sequence of two melting processes with mixtures of Tl₂S, Ta, and S having different molar metal to sulphur ratios. TlTaS₃ crystallises in space group Pnma with a = 9.228(3)Å, b = 3.5030(6)Å, c = 14.209(3)Å, V = 459.3(2)ų, Z = 4. The structure is closely related to the NH₄CdCl₃‐type. Characteristic features of the structure are chains of edge‐sharing [Ta(+5)S₄S_2/2]₂ double octahedra running along [010]. These columns are linked by Tl⁺ ions. The Tl⁺ ion is surrounded by eight S^2— anions to form a distorted bi‐capped trigonal prism. The Tl⁺ ions are shifted from the centre of the trigonal prism toward one of the rectangular faces. This is discussed in context with other isostructural compounds. TlTaS₃ is a semiconductor. The electronic structure is discussed on the base of band structure calculations performed within the framework of density functional theory.     

Syntheses and Crystal Structures of the Thallium(I) Iodobismuthates(III) Tl7Bi3I16 and Tl3BiI6

Dark grey (dark red with transmitting light) crystals of heptathallium(I) hexadecaiodo‐tribismuthate(III), Tl₇Bi₃I₁₆, were obtained by slow cooling of a melt from 800 K to ambient temperature and, with higher crystal quality via solvothermal synthesis in aqueous HI by slowly cooling from 428 to 363 K. The compound is diamagnetic and melts congruently at 630(5) K. X‐ray diffraction on single‐crystals revealed that Tl₇Bi₃I₁₆ crystallizes in the orthorhombic space group Cmcm with lattice parameters a = 2473.4(5), b = 1441.9(2), c = 3616.9(7) pm. The crystal structure can be interpreted as a layered intergrowth of fragments from the CsNiCl₃ and K₅Dy₃I₁₂ structure types with isolated [BiI₆]^3? octahedra and [Bi₂I₁₀]^4? double octahedra. Rotation and distortion of the complex anions establish coordination numbers (c.n.) between 7 and 9 for the Tl⁺ cations. Dark red crystals of trithallium(I) hexaiodo‐bismuthate(III), Tl₃BiI₆, are only accessible via hydrothermal synthesis in aqueous HI and slowly cooling from 428 to 363 K. Thermal analysis reveals a peritectoid decomposition at 540(5) K into the neighboring phases Tl₇Bi₃I₁₆ and TlI. Tl₃BiI₆ crystallizes in the monoclinic space group P2₁/c with lattice parameters a = 1352.6(3), b = 899.6(2), c = 1353.8(3) pm, and β = 104.18(3)°. In the crystal structure isolated [BiI₆]^3? octahedra are arranged according to the motif of a face‐centered pseudo‐cubic packing. Due to the tilted orientation of the [BiI₆]^3? groups the Tl⁺ cations have c.n. of 8 and 9. Although the crystal structure of Tl₃BiI₆ looks like a distorted variant of the elpasolith type, there is no symmetry relation according to a group subgroup formalism.     

Phase relations in the TlXTl2Se systems (X = Cl,Br, I) and the crystal structure of Tl5Se2I

Each of the quasibinary systems TlClTl₂Se, TlBrTl₂Se, and TlITl₂Se contains a region of solid solution up to 18 mole% Tl₂Se, which decomposes peritectically. The mixed crystals can be explained by a statistical substitution of Se by two I atoms on the fourfold sites of the Tl₂Se lattice. Compounds of the type Tl₅Se₂X were derived by complete substitution. Crystals of Tl₅Se₂I, suitable for a crystal structure determination, were grown by the Bridgman technique. Tl₅Se₂I is tetragonal, $\text{I4}\text{mcm}\text{; a = 866.3}\text{pm}\text{, c = 1346.3}\text{pm}\text{, Z = 4}$. The structure is an ordered variation of the In₅Bi₃ structure and isopuntal to the Cr₅B₃ type. The structure is formed basically by layers of Tl₂Se, in which strings of TlI are introduced. The compounds Tl₅Se₂Br (a = 861.1 pm, c = 1292.2 pm) and Tl₅Se₂Cl (a = 856.5 pm, c = 1273.3 pm) have probably very similar structures. A tendency for immiscibility in the TlXTl₂Se systems is shown by the existence of a miscibility gap in the system TlClTl₂Se and by the endothermic enthalpies of mixing in the system TlBrTl₂Se. In the TlITl₂Se system the compound Tl₆Se₄I system was encountered.     

Hochdrucksynthesen von Carbonaten. V. Carbonatdarstellungen durch Schmelzreaktionen unter hohen CO2-Drücken

High Pressure Syntheses of Carbonates. V. Syntheses of Carbonates by Melt Reactions under High CO₂ Pressure Binary compounds of transition metals react in melts of Tl₂CO₃ under CO₂ pressure from 1 000 to 5 000 bar by giving ternary carbonates. By this the compounds Tl₂Cu(CO₃)₂, TlCr(CO₃)₂, Tl₃Cr(CO₃)₃, and Tl₃V(CO₂)₃ could be prepared. The structure of Tl₂Cu(CO₃)₂ contains Cu₂ groups (a₀ = 7.583 Å, b₀ = 9.799 Å, c₀ = 9.119 Å, β 111.51°, Z = 4, space group P2₁/c Nr. 14). The space group of TlCr(CO₃)₂ is also P2₁/c Nr. 14 (a₀ = 19.917 Å, b₀ = 8.605 Å, c₀ = 19.138 Å, β = 104.79°, Z = 24). The compounds too were characterized by infrared spectroscopy.     

Piaselenol—Piaselenolium—Pentaiodid (C6H4N2Se · C6H5N2Se+I3− · I2), eine Struktur mit Polyiodid-schichten

Piaselenole—Piaselenolium—Pentaiodide (C₆H₄N₂Se · C₆H₅N₂Se⁺ I₃^? · I₂), a Structure with Polyiodide Layers The title compound crystallizes in the monoclinic space group P2₁/n with a = 9.320(3), b = 13.812(2), c = 17.159(3) Å, β = 96.11(2)°, V = 2196.3 ų, Z = 4. There occur no isolated I^5? anions but layer-shaped polyiodide aggregates built up by linear, asymmetric I₃^? anions and I₂ molecules. Almost linear triiodide chains are connected by I₂ molecules in a novel type of arrangement to form slightly puckered layers. The polyiodide layers contain several substructures known from other examples. The piaselenole and its conjugated acid, the piaselenolium cation, form a ribbon-like quasi-polymer in which the two components are alternating. They are connected in turns by a linear NH? N hydrogen bridge (N? N: 2.844 Å) and by a so called (SeN)₂-connectivity parallelogram, in which Se? N bonds and Se? N contacts are adjacent. Here we found a very short Se? N contact distance of 2.691 Å. The bond distances of piaselenole (Se? N: 1.787(3) Å, N? C: 1.318(5) Å, C? C: 1.453(8) Å) and also the angles are equal or similar to those occuring in other 1,2,5-selenadiazoles. The protonation of one N in the SeN₂ unit results in a loss of symmetry and significant changes in bonding distances and angles.     

Caesium Heptaiodo‐Dititanate(III), CsTi2I7

Caesium heptaiodo‐dititanate(III), CsTi₂I₇, is obtained from CsI, Ti and TiI₄ at 250 °C in a sealed tantalum ampoule as dark red single crystals. The crystal structure (trigonal, R‐3, a = 1706.6(3), c = 2088.3(5) pm, Z = 12, R1 = 0.0619) contains [TiI₄] tetrahedra sharing common vertices (with Ti—I—Ti angles of 180°) to isolated ditetrahedra [Ti₂I₇]^—. It may also be described as a cubic closest packing of alternating CsI₃ and I₄ layers between which neighbouring tetrahedra are occupied in a way that [Ti₂I₇]^— ditetrahedra are achieved. http://www.gerdmeyer.de     

1‐Methyl‐4‐nitraminopyridinium nitrate and 4‐nitraminopyridinium methanesulfonate

In the title compounds, C₆H₈N₃O₂⁺·NO₃^? and C₅­H₆­N₃­O₂⁺·­CH₃SO₃^?, respectively, the cations are almost planar; the twist of the nitr­amino group about the C—N and N—N bonds does not exceed 10°. The deviations from coplanarity are accounted for by intermolecular N—H?O interactions. The coplanarity of the NHNO₂ group and the phenyl ring leads to the deformation of the nitr­amino group. The C—N—N angle and one C—C—N angle at the junction of the phenyl ring and the nitr­amino group are increased from 120° by ca 6°, whereas the other junction C—C—N angle is decreased by ca 5°. Within the nitro group, the O—N—O angle is increased by ca 5° and one O—N—N angle is decreased by ca 5°, whereas the other O—N—N angle remains almost unchanged. The cations are connected to the anions by relatively strong N—H?O hydrogen bonds [shortest H?O separations 1.77 (2)–1.81 (3) Å] and much weaker C—H?O hydrogen bonds [H?O separations 2.30 (2)–2.63 (3) Å].     

NQR study of ternary chalcogenides A3BX3, ABX2, and ABX where A = Cu,Ag, or TI, B = As or Sb,and X = S or Se

¹²¹Sb, ¹²³Sb, ⁷⁵As, ⁶³Cu, and ⁶⁵Cu NQR resonances are reported for CuSbSe₂, Tl₃SbSe₃, Tl₃SbS₃, Tl₃AsS₃, Tl₃AsSe₃, Ag₃AsSe₃, TlSbS₂, CuAsS, AgAsS, and Cu₅SbS₃I₂. Tl₃SbSe₃ is an incongruently melting compound not observed in an earlier phase-diagram study of the pseudobinary system Tl₂SeSb₂Se₃. For isostructural arsenic and antimony chalcogenides the ratio of ⁷⁵As to ¹²¹Sb quadrupole coupling constants is 0.42, and for the BX₃ group in binary or ternary corresponding pairs of sulfide and selenides the ratio of quadrupole coupling constants for ⁷⁵As or ¹²¹Sb is 0.83. A reversible phase transition was observed at 130 K for Ag₃AsSe₃. Unit cell parameters are reported for crystals of TlSbS₂ and Cu₅SbS₃I₂.     

New thallium iodates—Synthesis, characterization, and calculations of Tl(IO3)3 and Tl4(IO3)6, [Tl3Tl(IO3)6]

Two new thallium iodates have been synthesized, Tl(IO₃)₃ and Tl₄(IO₃)₆ [Tl⁺₃Tl³⁺(IO₃)₆], and characterized by single-crystal X-ray diffraction. Both materials were synthesized as phase-pure compounds through hydrothermal techniques using Tl₂CO₃ and HIO₃ as reagents. The materials crystallize in space groups R-3 (Tl(IO₃)₃) and P-1 (Tl₄(IO₃)₆). Although lone-pairs are observed for both I⁵⁺ and Tl⁺, electronic structure calculations indicate the lone-pair on I⁵⁺ is stereo-active, whereas the lone-pair on Tl⁺ is inert.