Clamshell Opening in the Mixed-Metal Supramolecular Aggregates Formed by Fourfold Reduced Corannulene for Maximizing Intercalated Metal Content

The first members of a new class of supramolecular organometallic compounds with mixed-alkali-metal cluster cores, LiK5 and Li3K3, sandwiched between two four-fold reduced corannulene decks are prepared and fully characterized. The triple-decker supramolecular anions, [(C20H104-)(LiK5)(6+)(C20H104-)](2-) and [(C20H104-)(Li3K3)(6+)(C20H104-)](2-), illustrate a record ability of bowl-shaped and highly charged corannulene to provide all its sites, five benzene rings fused to a central five-membered ring, for binding of six alkali-metal ions. The previously unseen engagement of the hub-site of C20H104- in lithium binding is accompanied by unprecedented shifts up to -24ppm in Li-7 NMR spectra. The discussion of product formation mechanism, augmented by calculations, is provided.