Structures and Properties of the Halogenido Stannates(II) [BMIm][Sn3Cl7] and [BMIm][Sn4Br9].

The halogenido stannates(II) [BMIm][Sn3Cl7] and [BMIm][Sn4Br9] are obtained by ionic‐liquid‐based synthesis with SnX2 and [BMIm]X (X=Cl, Br; [BMIm]=1‐butyl‐3‐methylimidazolium) near room temperature (45–50 °C). Both form colorless, moisture‐sensitive crystals and exhibit layered anionic networks. [BMIm][Sn3Cl7] contains "horseshoe"‐like ∞1(SnCl1/1Cl2/2) chains that are linked via [SnCl3]− anions to ∞2[Sn3Cl7]− zigzag‐planes. [BMIm][Sn4Br9] contains a complex ∞2[Sn4Br9]− network with altogether four different crystallographic Sn2+ sites and different coordination. For comparison with these complex halogenido stannates(II), PbCl2/PbBr2 are reacted with similar conditions, which, however, only results in [BMIm][PbCl3] containing ∞1[PbCl3]− chains. Beside the crystal structures, the thermal and optical properties are examined and feature certain emission of visible light for all title compounds at room temperature. Whereas the quantum yields of [BMIm][Sn4Br9] (3 %) and [BMIm][PbCl3] (21 %) are low, [BMIm][Sn3Cl7] shows surprisingly efficient photoluminescence with a quantum yield of 46 %. [ABSTRACT FROM AUTHOR]