Revisiting [(RSn(IV))6Sn(III)2S12]: directed synthesis, crystal transformation, and luminescence properties

Current advances in tin cluster chemistry

This perspective summarizes highlights and most recent advances in tin cluster chemistry, thereby addressing the whole diversity of (mostly) discrete units containing tin atoms. Although being a (semi-)metallic element, tin is in the position to occur both in formally positive or negative oxidation states in these molecules, which causes a broad range of fundamentally different properties of the corresponding compounds. Tin(iv) compounds are not as oxophilic and not as prone to hydrolysis as related Si or Ge compounds, hence allowing for easier handling and potential application. Nevertheless, their reactivity is high due to an overall reduction of bond energies, which makes tin clusters interesting candidates for functional compounds. Beside aspects that point towards bioactivity or even medical applications, materials composed of naked or ligand-protected tin clusters, with or without bridging ligands, show interesting optical, and ion/molecule-trapping properties.

Formation and Structural Diversity of Organo-Functionalized Tin-Silver Selenide Clusters

When reacting the organic functionalized tin selenide clusters [(SnR¹ )₃ Se₄ Cl] (A, R¹ =CMe₂ CH₂ C(O)Me) or [(SnR¹ )₄ Se₆ ] (B) with (SiMe₃ )₂ Se and [Ag(PPh₃ )₃ Cl] at -78 °C in CH₂ Cl₂ , a microcrystalline intermediate (compound 1) precipitates, which was investigated by magic angle spinning (MAS) NMR spectroscopy, powder X-ray diffraction (PXRD), energy dispersive X-ray (EDX) spectroscopy, and quantum chemistry calculations, to derive information about its composition and structure. Compound 1 re-dissolves under reorganization into the organo-functionalized Ag/Sn/Se cluster compound [Ag₆ (μ₆ -Se)(Ag₈ Se₁₂ ){(R¹ Sn)₂ Se₂ }₆ ] (2), or the mixed-valence cluster [(AgPPh₃ )₂ (Sn^II Cl)₂ Se₂ {(R¹ Sn^IV )₂ Se₂ }₂ ] (3), depending on the presence or the exclusion of daylight, respectively. The addition of N₂ H₄ ⋅H₂ O to a solution of 1 yields selectively [Ag₇ (μ₇ -Se)(Ag₇ Se₁₂ ){(R² Sn)₂ Se₂ }₆ ] (4, R² =CMe₂ CH₂ C(N₂ H₂ )Me), the Ag/Sn/Se core of which is isomeric to that of 2. 2-4 were characterized by X-ray diffraction. NMR spectroscopic studies on solutions of 1 indicate the co-existence of different species.

Tin sulfide and selenide clusters soluble in organic solvents with the core structures of Sn4S6 and Sn4Se6

Reactions of LSnCl (1) (L = N(2,6-iPr2C6H3)(SiMe3)) with sulfur and selenium, respectively under mild conditions yielded two tin chalcogenide clusters. Surprisingly the tin atoms of the L4Sn4S6 (2) and L4Sn4Se6 (3) clusters are oxidized from Sn(II) of the precursor to Sn(IV) of the products under concomitant reduction of elemental sulfur and selenium to sulfide and selenide, respectively. The released chlorine radicals from the precursor LSnCl (1) react under oxidative addition with another LSnCl molecule to yield the side product LSnCl3 (4). The soluble nature of clusters 2 and 3 in organic solvents is a unique property of this class of compounds and makes them suitable for reactions in organic solvents. Compounds 2 and 3 were characterized by single crystal X-ray diffraction and multinuclear NMR investigations. Furthermore in ROP polymerization, the two products show high catalytic activity. For the first time a tin selenide compound functions in ROP catalysis.

Synthesis and Thorough Investigation of Discrete Organotin Telluride Clusters

Systematic experimental and theoretical investigations of reactions of R(1)SnCl3 (R(1) = CMe2CH2C(Me)O) with (Me3Si)2Te allowed for the stepwise formation and single-crystalline isolation of the first tin sesquitelluride clusters with functional organic ligands. Subsequent derivatization of the latter took place under reorganization of the inorganic core, affording clusters with complex hybrid architectures.