Heterometallic Clusters [CuSn 3 S 9 ] 5− and [Cu 6 Sn 6 S 20 ] 10− : Solvothermal Synthesis and Characterization of 4f–3d Thiostannates

Two types of 4f–3d thiostannates with general formula [Hen] 2 [Ln(en) 4 (CuSn 3 S 9 )] ⋅ 0.5 en ( Ln1 ; Ln=La, 1 ; Ce, 2 ) and [Hen] 4 [Ln(en) 4 ] 2 [Cu 6 Sn 6 S 20 ] ⋅ 3 en ( Ln2 ; Ln=Nd, 3 ; Gd, 4 ; Er, 5 ) were prepared by reactions of Ln 2 O 3 , Cu, Sn, and S in ethylenediamine (en) under solvothermal conditions between 160 and 190 °C. However, reactions performed in the range from 120 to 140 °C resulted in crystallization of [Sn 2 S 6 ] 4− compounds and CuS powder. In 1 and 2 , three SnS 4 tetrahedra and one CuS 3 triangle are joined by sharing sulfur atoms to form a novel [CuSn 3 S 9 ] 5− cluster that coordinates to the Ln 3+ ion of [Ln(en) 4 ] 3+ (Ln=La, Ce) as a monodentate ligand. The [CuSn 3 S 9 ] 5− unit is the first thio‐based heterometallic adamantane‐like cluster coordinating to a lanthanide center. In 3 – 5 , six SnS 4 tetrahedra and six CuS 3 triangles are connected by sharing common sulfur atoms to form the ternary [Cu 6 Sn 6 S 20 ] 10− cluster, in which a Cu 6 core is enclosed by two Sn 3 S 10 fragments. The topological structure of the novel Cu 6 core can be regarded as two Cu 4 tetrahedra joined by a common edge. The Ln 3+ ions in Ln1 and Ln2 are in nine‐ and eightfold coordination, respectively, which leads to the formation of the [CuSn 3 S 9 ] 5− and [Cu 6 Sn 6 S 20 ] 10− clusters under identical synthetic conditions. The syntheses of Ln1 and Ln2 show the influence of the lanthanide contraction on the quaternary Ln/Cu/Sn/S system in ethylenediamine. Compounds 1 – 5 exhibit bandgaps in the range of 2.09–2.48 eV depending on the two different types of clusters in the compounds. Compounds 1 , 3 , and 4 lost their organic components in the temperature range of 110–350 °C by multistep processes.