Ionic Liquid‐Driven Formation of and Cation Exchange in Layered Sulfido Stannates – a CH₂ Group Makes the Difference

Abstract

Two types of layered sulfido stannates or a molecular cluster compound are obtained upon ionothermal treatment of the simple sulfido stannate salt K4[SnS4] · 4H2O that is based on binary tetrahedral [SnS4]4− anions. The formation of the respective products, novel compounds (C4C1C1Im)2[Sn3S7] (1 a), (C4C1C2Im)2[Sn3S7] (1 b), and (C4C1C2Im)2[Sn4S9] (2) with layered anionic substructures, or the recently reported compound (C4C1C1Im)4+x[Sn10O4S16(SMe)4][An]x (A) comprising a molecular cluster anion, is controlled by both the choice of the ionic liquid cation and the reaction temperature. We report the scale‐up of the syntheses by a factor of 100 with regard to other reported ionothermal syntheses of related compounds, and a procedure of how to isolate them in phase‐pure form – both being rare observations in chalcogenido stannate chemistry in ionic liquids. Moreover, the synthesis of compound 1 a can be achieved by rapid cation exchange starting out from 1 b, which has not been reported for organic cations in any chalcogenido stannate salt to date.

Layered Thiostannates with Distinct Arrangements of Mixed Cations for the Selective Capture of Cs+, Sr2+, and Eu3+ Ions

“…In FJSM-SnS-3, the interlaminar distance containing the mixed [CH 3 NH 3 ] + and [Bmmim] + is estimated to be 11.383 Å, which is bigger than that of FJSM-SnS-2. Although thiostannates containing a 2D anionic [Sn 3 S 7 ] n 2 n– network with a variety of cations have been reported (see Table S2), ,− it is first found that interlayer spaces of [Sn 3 S 7 ] n 2 n– accommodate the mixed cations of large-sized ionic liquid cations and small-sized protonated organic amines in FJSM-SnS-2 and FJSM-SnS-3. The arrangements of two types of cations between different layers are extremely rare for layered sulfides, showing the unique charm of the mixed template method.…”

“…The development of metal sulfide ion exchangers greatly depends on the improvement of synthesis methods. The ionothermal method has recently caught attention due to the specific ionic environment of ionic liquids (ILs) with unique solvent properties aiding the formation of novel compounds that are inaccessible in molecular solvents. − The cation of ILs (typically imidazolium cations) can act as a charge balance agent and structure directing agent to induce the formation of 2D layered or 3D microporous frameworks. − However, 2D and 3D chalcogenides synthesized by the ionothermal method mainly focus on metal selenides up to now. The open frameworks of metal sulfides prepared in ILs are still rare …”

“…The open frameworks of metal sulfides prepared in ILs are still rare. 48 Combining our previous successful strategies on the application of exchangeable small protonated organic amine cations 37,38,40,49,50,52 and the preparation of metal selenides in ILs, 43−45 herein, the mixed solvents of IL (i.e., [Bmmim]Cl, 1butyl-2,3-dimethylimidazolium chloride) and methylamine aqueous solution were applied to prepare two new 2D layered thiostannates under solvothermal conditions, namely,…”