Alkyltin Keggin Clusters Templated by Sodium

Abstract

Dodecameric (Sn₁₂ ) and hexameric topologies dominate monoalkyltin-oxo cluster chemistry. Their condensation, triggered by radiation exposure, recently produced unprecedented patterning performance in EUV lithography. A new cluster topology was crystallized from industrial n-BuSnOOH, and additional characterization techniques indicate other clusters are present. Single-crystal X-ray analysis reveals a β-Keggin cluster, which is known but less common than other Keggin isomers in polyoxometalate and polyoxocation chemistry. The structure is formulated [NaO₄ (BuSn)₁₂ (OH)₃ (O)₉ (OCH₃ )₁₂ (Sn(H₂ O)₂ )] (β-NaSn₁₃ ). SAXS, NMR, and ESI MS differentiate β-NaSn₁₃ , Sn₁₂ , and other clusters present in crude "n-BuSnOOH" and highlight the role of Na as a template for alkyltin Keggin clusters. Unlike other alkyltin clusters that are cationic, β-NaSn₁₃ is neutral. Consequently, it stands as a unique model system, absent of counterions, to study the transformation of clusters to films and nanopatterns.