Access of Adamantane-Type Organotin(IV) Heterochalcogenide Clusters

The access of metal chalcogenide clusters with tunable properties remains challenging. For a given geometric cluster structure, chemical and physical properties are defined by the exact composition. With a binary metal chalcogenide cluster core, one can reach a certain degree of tunability, but an even finer definition is possible by expanding the concept to ternary cluster composition. As a case example, we address adamantane-type organotin chalcogenide clusters of the general composition [(RSn)$_4$E$_6$] (R = organic group, E = Se, Te) and herein report the targeted access of corresponding species exhibiting ternary clusters with two different types of chalcogen atoms involved, [(RSn)$_4$E$_{6–x}$E′$_x$]. We report three different methods for the synthetic access of E/E′ mixtures, including chalcogen exchange between preformed homochalcogenide clusters [(RSn)$_4$E$_6$] and[(RSn)$_4$E′$_6$] in solution. Extensive $^{119}$Sn NMR studies on corresponding reaction mixtures with different ratios of the starting materials, in combination with sophisticated quantum chemical calculations of the chemical shifts, unambiguously confirm that all statistically possible clusters form in solution. Isolation of selected species in single-crystalline form also indicates the existence of ternary cluster cores with a narrow dispersion of species around the given E:E′ ratios. Our results represent an important step toward fine-tuning of metal chalcogenide cluster-based materials.