Straightforward Route to the Adamantane Clusters [Sn₄Q₁₀]⁴⁻ (Q = S, Se, Te) and Use in the Assembly of Open-Framework Chalcogenides (Me₄N)₂M[Sn₄Se₁₀] (M = Mn^II, Fe^II, Co^II, Zn^II) Including the First Telluride Member (Me₄N)₂Mn[Ge₄Te₁₀]

The reaction of K2Sn2Q5 (Q = S, Se, Te) with stoichiometric amounts of alkyl-ammonium bromides R4NBr (R = methyl or ethyl) in ethylenediamine (en) afforded the corresponding salts (R4N)4[Sn4Q10] (Q = S, Se, Te) in high yield. Although the compound K2Sn2Te5 is not known, this reaction is also applicable to solids with a nominal composition “K2Sn2Te5” which in the presence of R4NBr in en are quantitatively converted to the salts (R4N)4[Sn4Te10] on a multigram scale. These salts contain the molecular adamantane clusters [Sn4Q10]4− and can serve as soluble precursors in simple metathesis reactions with transition metal salts to synthesize the large family of open-framework compounds (Me4N)2M[Sn4Se10] (M = Mn2+, Fe2+, Co2+, Zn2+). Full structural characterization of these materials as well as their magnetic and optical properties is reported. Depending on the transition metal in (Me4N)2M[Sn4Se10], the energy band gaps of these compounds lie in the range of 1.27−2.23 eV. (Me4N)2Mn[Ge4Te10] is the first telluride analogue to be reported in this family. This material is a narrow band gap semiconductor with an optical absorption energy of 0.69 eV. Ab initio electronic band structure calculations validate the semiconductor nature of these chalcogenides and indicate a nearly direct band gap.