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Metalloid Tin Clusters, SnntBum, with α-Sn-Like Structural Motifs
Metalloid tin clusters represent an intriguing class of compounds that bridge molecular chemistry and the solid state, yet access to diverse examples remains limited. Herein, we present a mild, modular hydrostannolysis-type strategy that enables the synthesis of tin-based clusters stabilized by fairly small tert-butyl substituents, thereby overcoming the ligand-imposed structural limitations of established methodologies. The approach gave access to a series of clusters of different core sizes, including Sn11tBu12, featuring a [1.1.1]propellane-type backbone, as well as larger Sn15tBu14 and Sn16tBu16 derivatives adopting α-Sn-like core motifs with chair arrangement reminiscent of the diamond-type structure. Experimental characterization (X-ray crystallography and 119Sn Mössbauer spectroscopy) and computational analyses (NBO and QTAIM) corroborate near-zero charges at the apical tin centers; the frontier orbitals show pronounced multicenter character across the tin framework, and several deeper-lying orbitals exhibit “superatom”-like character. Additionally, this synthetic protocol also afforded a unique, heterobimetallic Sn/Pb spiro compound, revealing the compatibility of the method with multiple group 14 elements.
