Tuning the Electronic Structure of Atomically Precise Sn/Co/Se Nanoclusters via Redox Matching of Tin(IV) Surface Sites.

A new strategy is reported to tailor the electronic properties of a superatomic metal chalcogenide cluster by redox matching the cluster core with surface tin(IV) sites. Two ternary clusters (SnR ₂ ) ₃ Co ₆ Se ₈ L ₆ (R = Me, ⁿ Bu) are synthesized by salt metathesis from the hexalithiated salt [Li ₂ (py) ₂ ] ₃ Co ₆ Se ₈ L ₆ and R ₂ SnCl ₂ . Cyclic and differential-pulse voltammetry studies reveal that the tristannylated clusters feature two new, near-degenerate, electronic states within the highest occupied molecular orbital-lowest unoccupied molecular orbital gap of the Co ₆ Se ₈ core, which are attributed to the reduction of a surface tin site. Single-crystal X-ray diffraction analysis reveals that no Sn···Se coordination is present in the solid state. The single-crystal X-ray structure of the hexalithiated salt starting material is reported for the tetrahydrofuran (THF) adduct variant [Li ₂ (THF) ₂ ] ₆ Co ₆ Se ₈ L ₆ .