Fast Preparation of Dimorphic Thioantimonates and a Thioantimonate with a Hitherto Unknown Network Topology Applying a New Synthesis Approach

The reaction of an aqueous solution of Na₃SbS₃ with [Ni­(terpy)₂]²⁺ (terpy = 2,2′:6′,2″-terpyridine) afforded crystallization of three new thioantimonates in short reaction times. Two polymorphic compounds, [Ni­(terpy)₂]­[Sb₄S₇]­·H₂O (<b>1</b>, <b>2</b>), were obtained simultaneously under identical reaction conditions, while an increase of the reaction temperature led to formation of the third compound [Ni­(terpy)₂]₂­[Sb₁₀S₁₇] (<b>3</b>). In <b>1</b> the anion consists of a [Sb₄S₇]^2– chain, whereas <b>2</b> is composed of a layered [Sb₄S₇]^2– anion. Form <b>2</b> disappeared at longer reaction times, and therefore modification <b>1</b> might represent the thermodynamically stable form at this temperature despite the lower density compared to <b>2</b>. Storing modification <b>1</b> at elevated temperatures the water can partly be removed in a topotactic reaction leading to the compound [Ni­(terpy)₂]­[Sb₄S₇]­·0.25 H₂O (<b>1A</b>). Compound <b>3</b> exhibits a unique Sb:S ratio, and a never before observed network topology significantly enhancing the structural diversity of thioantimonates­(III)

Influence of the Synthesis Parameters onto Nucleation and Crystallization of Five New Tin–Sulfur Containing Compounds

The distinct control of the synthesis parameters achieved crystallization of five new inorganic–organic hybrid tin sulfides with 1,10-phenanthroline (phen) as the organic component: {[Mn­(phen)₂]₂(μ₂-Sn₂S₆)} (<b>1</b>, <b>3</b>), {[Mn­(phen)₂]₂(μ₂-Sn₂S₆)}·phen (<b>2</b>), {[Mn­(phen)₂]₂(μ₂-Sn₂S₆)}·phen·H₂O (<b>4</b>), and {[Mn­(phen)₂]₂[μ-η²-η²-SnS₄]₂[Mn­(phen)]₂}·H₂O (<b>5</b>). Compounds <b>1</b>, <b>3</b>, and <b>4</b> occur successively under static conditions by increasing the reaction time up to 8 weeks. Stirring the reaction mixtures and keeping the educt ratio constant allow preparation of distinct phase pure samples within very short reaction times. At higher autogenous pressure, crystallization and conversion of several compounds are suppressed, and only <b>1</b> crystallized. Compound <b>2</b> could only be obtained in glass tubes at low pH value of the reaction mixture or at low amine concentration. Adjusting the pH value of the solution, the concentration, and the volume of the solvent, compounds <b>1</b>–<b>4</b> crystallize sequentially and were successively converted into each other. Results of thermal stability experiments and solubility studies suggest that compounds <b>1</b> and <b>3</b> are polymorphs following the density rule. Compounds <b>2</b> and <b>4</b> may be viewed as pseudopolymorphs of <b>1</b> and <b>3</b>

Applying Ni(II) Amine Complexes and Sodium Thiostannate as Educts for the Generation of Thiostannates at Room Temperature

A new versatile and fast room temperature synthesis route was developed in which Na₄SnS₄·14H₂O and selected Ni­(II)­amine complexes (amine = ethylenediamine (en), 1,2-diaminocyclohexane (1,2-dach), 1,2-diaminopropane (1,2-dap), 2-(aminomethyl)­pyridine (2amp)) were reacted in aqueous tren (tren = tris­(2-aminoethyl)­amine) solutions affording crystallization of six new compounds. During the reaction heteroleptic Ni²⁺ centered complexes are formed in situ by replacement of two bidentate ligands by the tetradentate tren molecule. The compounds poorer in water of the pseudopolymorphs of [Ni­(tren)­(en)]₂­[Sn₂S₆]­·<i>x</i>H₂O (<i>x</i> = 2 (<b>1</b>) and 6 (<b>2</b>)) and [Ni­(tren)­(1,2-dach)]₂­[Sn₂S₆]­·<i>x</i>H₂O (<i>x</i> = 3 (<b>3</b>) and 4 (<b>4</b>)) are formed after a very short reaction time of 1 day. Remarkably, keeping the reaction slurries at room temperature for 7 days the thermodynamically stable water richer compounds were obtained. The remaining compounds, [Ni­(tren)­(1,2-dap)]₂­[Sn₂S₆]­·4H₂O (<b>5</b>) and [Ni­(tren)­(2amp)]₂­[Sn₂S₆]­·10H₂O (<b>6</b>), crystallized between 1 and 7 days. The water of crystallization molecules in all compounds are involved in extended hydrogen bonding interactions significantly affecting the packing of cations and anions. Hirshfeld surfaces analyses give a detailed picture of intermolecular interactions which lead to the different packing motifs in the crystal structures

Sulfide Catalysis without Coordinatively Unsaturated Sites: Hydrogenation, Cis–Trans Isomerization, and H₂/D₂ Scrambling over MoS₂ and WS₂

Simple test reactions as ethene hydrogenation, 2-butene cis–trans isomerization and H₂/D₂ scrambling were shown to be catalyzed by MoS₂ and WS₂ in surface states which did not chemisorb oxygen and were, according to XPS analysis, saturated by sulfide species. This is a clear experimental disproof of classical concepts that require coordinative unsaturation for catalytic reactions to occur on such surfaces. It supports new concepts developed on model catalysts and by theoretical calculations so far, which have been in need of confirmation from real catalysis

Room-Temperature Synthesis of Thiostannates from {[Ni(tren)]₂[Sn₂S₆]}_<i>n</i>

The compound {[Ni­(tren)]₂[Sn₂S₆]}_<i>n</i> (<b>1</b>) (tren = tris­(2-aminoethyl)­amine, C₆H₁₈N₄) was successfully applied as source for the room-temperature synthesis of the new thiostannates [Ni­(tren)­(ma)­(H₂O)]₂[Sn₂S₆]·4H₂O (<b>2</b>) (ma = methylamine, CH₅N) and [Ni­(tren)­(1,2-dap)]₂[Sn₂S₆]·2H₂O (<b>3</b>) (1,2-dap = 1,2-diaminopropane, C₃H₁₀N₂). The Ni–S bonds in the Ni₂S₂N₈ bioctahedron in the structure of <b>1</b> are analyzed with density functional theory calculations demonstrating significantly differing Ni–S bond strengths. Because of this asymmetry they are easily broken in the presence of an excess of ma or 1,2-dap immediately followed by Ni–N bond formation to N donor atoms of the amine ligands thus generating [Ni­(tren)­(amine)]²⁺ complexes. The chemical reactions are fast, and compounds <b>2</b> and <b>3</b> are formed within 1 h. The synthesis concept presented here opens hitherto unknown possibilities for preparation of new thiostannates

Expansion of Antimonato Polyoxovanadates with Transition Metal Complexes: (Co(N₃C₅H₁₅)₂)₂[{Co(N₃C₅H₁₅)₂}V₁₅Sb₆O₄₂(H₂O)]·5H₂O and (Ni(N₃C₅H₁₅)₂)₂[{Ni(N₃C₅H₁₅)₂}V₁₅Sb₆O₄₂(H₂O)]·8H₂O

Two new polyoxovanadates (Co­(N₃C₅H₁₅)₂)₂[{Co­(N₃C₅H₁₅)₂}­V₁₅Sb₆O₄₂(H₂O)]·5H₂O (<b>1</b>) and (Ni­(N₃C₅H₁₅)₂)₂[{Ni­(N₃C₅H₁₅)₂}­V₁₅Sb₆O₄₂(H₂O)]·8H₂O (<b>2</b>) (N₃C₅H₁₅ = <i>N</i>-(2-aminoethyl)-1,3-propanediamine) were synthesized under solvothermal conditions and structurally characterized. In both structures the [V₁₅Sb₆O₄₂(H₂O)]^6– shell displays the main structural motif, which is strongly related to the {V₁₈O₄₂} archetype cluster. Both compounds crystallize in the triclinic space group <i>P</i>1̅ with <i>a</i> = 14.3438(4), <i>b</i> = 16.6471(6), <i>c</i> = 18.9186(6) Å, α = 87.291(3)°, β = 83.340(3)°, γ = 78.890(3)°, and <i>V</i> = 4401.4(2) ų (<b>1</b>) and <i>a</i> = 14.5697(13), <i>b</i> = 15.8523(16), <i>c</i> = 20.2411(18) Å, α = 86.702(11)°, β = 84.957(11)°, γ = 76.941(11)°, and <i>V</i> = 4533.0(7) ų (<b>2</b>). In the structure of <b>1</b> the [V₁₅Sb₆O₄₂(H₂O)]^6– cluster anion is bound to a [Co­(N₃C₅H₁₅)₂]²⁺ complex via a terminal oxygen atom. In the Co²⁺-centered complex, one of the amine ligands coordinates in tridentate mode and the second one in bidentate mode to form a strongly distorted CoN₅O octahedron. Similarly, in compound <b>2</b> an analogous NiN₅O complex is joined to the [V₁₅Sb₆O₄₂(H₂O)]^6– anion via the same attachment mode. A remarkable difference between the two compounds is the orientation of the noncoordinated propylamine group leading to intermolecular Sb···O contacts in <b>1</b> and to Sb···N interactions in <b>2</b>. In the solid-state lattices of <b>1</b> and <b>2</b>, two additional [M­(N₃C₅H₁₅)₂]²⁺ complexes act as countercations and are located between the [{M­(N₃C₅H₁₅)₂}­V₁₅Sb₆O₄₂(H₂O)]^4– anions. Between the anions and cations strong N–H···O hydrogen bonds are observed. In both compounds the clusters are stacked along the <i>b</i> axis in an ABAB fashion with cations and water molecules occupying the space between the clusters. Magnetic characterization demonstrates that the Ni²⁺ and Co²⁺ cations do not significantly couple with the <i>S</i> = 1/2 vanadyl groups. The susceptibility data can be successfully reproduced assuming a distorted ligand field for the Co²⁺ ions (<b>1</b>) and an <i>O</i>_<i>h</i>-symmetric Ni²⁺ ligand field (<b>2</b>)

Expansion of Antimonato Polyoxovanadates with Transition Metal Complexes: (Co(N₃C₅H₁₅)₂)₂[{Co(N₃C₅H₁₅)₂}V₁₅Sb₆O₄₂(H₂O)]·5H₂O and (Ni(N₃C₅H₁₅)₂)₂[{Ni(N₃C₅H₁₅)₂}V₁₅Sb₆O₄₂(H₂O)]·8H₂O

Two new polyoxovanadates (Co­(N₃C₅H₁₅)₂)₂[{Co­(N₃C₅H₁₅)₂}­V₁₅Sb₆O₄₂(H₂O)]·5H₂O (<b>1</b>) and (Ni­(N₃C₅H₁₅)₂)₂[{Ni­(N₃C₅H₁₅)₂}­V₁₅Sb₆O₄₂(H₂O)]·8H₂O (<b>2</b>) (N₃C₅H₁₅ = <i>N</i>-(2-aminoethyl)-1,3-propanediamine) were synthesized under solvothermal conditions and structurally characterized. In both structures the [V₁₅Sb₆O₄₂(H₂O)]^6– shell displays the main structural motif, which is strongly related to the {V₁₈O₄₂} archetype cluster. Both compounds crystallize in the triclinic space group <i>P</i>1̅ with <i>a</i> = 14.3438(4), <i>b</i> = 16.6471(6), <i>c</i> = 18.9186(6) Å, α = 87.291(3)°, β = 83.340(3)°, γ = 78.890(3)°, and <i>V</i> = 4401.4(2) ų (<b>1</b>) and <i>a</i> = 14.5697(13), <i>b</i> = 15.8523(16), <i>c</i> = 20.2411(18) Å, α = 86.702(11)°, β = 84.957(11)°, γ = 76.941(11)°, and <i>V</i> = 4533.0(7) ų (<b>2</b>). In the structure of <b>1</b> the [V₁₅Sb₆O₄₂(H₂O)]^6– cluster anion is bound to a [Co­(N₃C₅H₁₅)₂]²⁺ complex via a terminal oxygen atom. In the Co²⁺-centered complex, one of the amine ligands coordinates in tridentate mode and the second one in bidentate mode to form a strongly distorted CoN₅O octahedron. Similarly, in compound <b>2</b> an analogous NiN₅O complex is joined to the [V₁₅Sb₆O₄₂(H₂O)]^6– anion via the same attachment mode. A remarkable difference between the two compounds is the orientation of the noncoordinated propylamine group leading to intermolecular Sb···O contacts in <b>1</b> and to Sb···N interactions in <b>2</b>. In the solid-state lattices of <b>1</b> and <b>2</b>, two additional [M­(N₃C₅H₁₅)₂]²⁺ complexes act as countercations and are located between the [{M­(N₃C₅H₁₅)₂}­V₁₅Sb₆O₄₂(H₂O)]^4– anions. Between the anions and cations strong N–H···O hydrogen bonds are observed. In both compounds the clusters are stacked along the <i>b</i> axis in an ABAB fashion with cations and water molecules occupying the space between the clusters. Magnetic characterization demonstrates that the Ni²⁺ and Co²⁺ cations do not significantly couple with the <i>S</i> = 1/2 vanadyl groups. The susceptibility data can be successfully reproduced assuming a distorted ligand field for the Co²⁺ ions (<b>1</b>) and an <i>O</i>_<i>h</i>-symmetric Ni²⁺ ligand field (<b>2</b>)

Syntheses and structures of two new lithium-heptamolybdates

<p>The synthesis, crystal structures, IR, UV–vis, ⁷Li NMR spectra, electrochemical investigations, and conductivity studies of two new lithium-heptamolybdates, (NH₄)₄[Li₂(H₂O)₇][Mo₇O₂₄]·H₂O (<b>1</b>) and (NH₄)₃[Li₃(H₂O)₄(<i>μ</i>₆-Mo₇O₂₄)]·2H₂O (<b>2</b>), are reported. In <b>1</b> the (NH₄)⁺ and [Li₂(H₂O)₇]²⁺, cations are charge balanced by the heptamolybdate anion. In <b>2</b>, the [Mo₇O₂₄]⁶⁻ anion is coordinated to three unique Li⁺ ions via a <i>μ</i>₆-hexadentate-binding mode resulting in the formation of a two-dimensional (2-D) [Li₃(H₂O)₄(<i>μ</i>₆-Mo₇O₂₄)]³⁻ anionic complex, charge neutralized by three (NH₄)⁺ ions. The cations, anions, and the lattice water molecules in <b>1</b> and <b>2</b> are linked by weak H-bonding interactions.</p

Covalent Co–O–V and Sb–N Bonds Enable Polyoxovanadate Charge Control

The formation of [{Co^II(teta)₂}­{Co^II₂(tren)­(teta)₂}­V^IV₁₅Sb^III₆O₄₂(H₂O)]·ca.9H₂O [teta = triethylenetetraamine; tren = tris­(2-aminoethyl)­amine] illustrates a strategy toward reducing the molecular charge of polyoxovanadates, a key challenge in their use as components in single-molecule electronics. Here, a V–O–Co bond to a binuclear Co²⁺-centered complex and a Sb–N bond to the terminal N atom of a teta ligand of a mononuclear Co²⁺ complex allow for full charge compensation of the archetypal molecular magnet [V₁₅Sb₆O₄₂(H₂O)]^6–. Density functional theory based electron localization function analysis demonstrates that the Sb–N bond has an electron density similar to that of a Sb–O bond. Magnetic exchange coupling between the V^IV and Co^II spin centers mediated via the Sb–N bridge is comparably weakly antiferromagnetic

CuV₂S₄: A High Rate Capacity and Stable Anode Material for Sodium Ion Batteries

The ternary compound CuV₂S₄ exhibits an excellent performance as anode material for sodium ion batteries with a high reversible capacity of 580 mAh g^–1 at 0.7 A g^–1 after 300 cycles. A Coulombic efficiency of ≈99% is achieved after the third cycle. Increase of the C-rate leads to a drop of the capacity, but a full recovery is observed after switching back to the initial C-rate. In the early stages of Na uptake first Cu⁺ is reduced and expelled from the electrode as nanocrystalline metallic Cu. An increase of the Na content leads to a full conversion of the material with nanocrystalline Cu particles and elemental V embedded in a Na₂S matrix. The formation of Na₂S is evidenced by ²³Na MAS NMR spectra and X-ray powder diffraction. During the charge process the nanocrystalline Cu particles are retained, but no crystalline materials are formed. At later stages of cycling the reaction mechanism changes which is accompanied by the formation of copper­(I) sulfide. The presence of nanocrystalline metallic Cu and/or Cu₂S improves the electrical conductivity, leading to superior cycling and rate capability