Encapsulation of Inorganic NaX in Caged Sodium Alkoxide Clusters X@RONa: Scalable Syntheses, Structural Variations, and Mechanism Elucidation

Abstract Atom-economical synthesis of dodecameric caged sodium alkoxide clusters encapsulating X anions (X@RONa) using simple NaOR and inorganic NaX as precursors was developed. With finely ground NaX powder, heating NaOR in a nonpolar solvent at 130 °C for a few hours allowed encapsulation of NaX and formation of X@RONa in high yield without much waste. The structural diversity of the encapsulated anion X was greatly expanded to include poor leaving groups such as borohydride, amide, and hydroxide, and the exterior R group was extended to a great variety of alkyls and their hybrids. The formation mechanism of X@RONa was proposed to involve a new deformed fluxional hexamer of RONa, which likely facilitated NaX encapsulation by its vacant sodium sites.