Die elektrochemische Synthese polykationischer Cluster

Coexistence of Tellurium Cations and Anions in Phosphonium-Based Ionic Liquids

Elemental tellurium readily dissolves in ionic liquids (ILs) based on tetraalkylphosphonium cations even at temperatures below 100 °C. In the case of ILs with acetate, decanoate, or dicyanamide anions, dark red to purple colored solutions form. A study combining NMR, UV‐Vis and Raman spectroscopy revealed the formation of tellurium anions (Te_n)²⁻ with chain lengths up to at least n=5, which are in dynamic equilibrium with each other. Since external influences could be excluded and no evidence of an ionic liquid reaction was found, disproportionation of the tellurium is the only possible dissolution mechanism. Although the spectroscopic detection of tellurium cations in these solutions is difficult, the coexistence of tellurium cations, such as (Te₄)²⁺ and (Te₆)⁴⁺, and tellurium anions could be proven by cyclic voltammetry and electrodeposition experiments. DFT calculations indicate that electrostatic interactions with the ions of the ILs are sufficient to stabilize both types of tellurium ions in solution.

TiCl4 Dissolved in Ionic Liquid Mixtures from ab Initio Molecular Dynamics Simulations

To gain a deeper understanding of the TiCl4 solvation effects in multi-component ionic liquids, we performed ab initio molecular dynamics simulations of 1-butyl-3-methylimidazolium [C4C1Im]+, tetrafluoroborate [BF4]−, chloride [Cl]− both with and without water and titanium tetrachloride TiCl4. Complex interactions between cations and anions are observed in all investigated systems. By further addition of water and TiCl4 this complex interaction network is extended. Observations of the radial distribution functions and number integrals show that water and TiCl4 not only compete with each other to interact mainly with [Cl]−, which strongly influences the cation-[BF4]− interaction, but also interact with each other, which leads to the fact that in certain systems the cation-anion interaction is enhanced. Further investigations of the Voronoi polyhedra analysis have demonstrated that water has a greater impact on the nanosegregated system than TiCl4 which is also due to the fact of the shear amount of water relative to all other components and its higher mobility compared to TiCl4. Overall, the polar network of the IL mixture collapses by including water and TiCl4. In the case of [Cl]− chloride enters the water continuum, while [BF4]− remains largely unaffected, which deeply affects the interaction of the ionic liquid (IL) network.

Multi-Valent Group 14 Chalcogenide Architectures from Ionic Liquids: 0D-{[Cs@SnII4 (GeIV4 Se10 )4 ]7- } and 2D-{[SnII (GeIV4 Se10 )]2- }

In order to explore if and how salts comprising polycations and salts comprising polyanions might interact, the [AlBr₄ ]^- salt of the [Pt@Bi₁₀ ]⁴⁺ cluster cation was added to the reaction mixture for the synthesis of the supersphere cluster anion [Ge₂₄ Sn₃₆ Se₁₃₂ ]^24- from Cs₄ [Ge₄ Se₁₀ ]⋅H₂ O and SnCl₄ ⋅5 H₂ O under ionothermal conditions at 120 °C. Indeed, the reaction yields two new compounds, depending on the cation of the used ionic liquid. Apparently, the polycation is not retained under the given conditions, but it acts as a reductant affording Sn^II . In a (C₄ C₁ C₁ im)⁺ -based ionic liquid mixture, a unique supertetrahedral anion is obtained that embeds a Cs⁺ cation, 0D-{[Cs@Sn^II₄ (Ge^IV₄ Se₁₀ )₄ ]^7- }, while (C₄ C₁ im)⁺ cations stabilize an unprecedented ternary layered anion, 2D-{[Sn^II (Ge^IV₄ Se₁₀ )]^2- }. Test reactions with common sources of Sn^II did not afford the new compounds, indicating the necessity of an in situ reduction, for which the polycation seems appropriate.