| Abstract: | The controlled reaction of Na and Cs, two alkali metals of different ionic sizes and binding abilities, with sumanene (C21H12) affords a novel type of organometallic sandwich Cs(C21H11−)2]−, which crystallized as a solvent‐separated ion pair with a Na(18‐crown‐6)(THF)2]+ cation (where THF=tetrahydrofuran). The unprecedented double concave encapsulation of a metal ion by two bowl‐shaped sumanenyl anions in Cs(C21H11−)2]− was revealed crystallographically. Evaluation of bonding and energetics of the remarkable product was accomplished computationally (B2PLYP‐D/TZVP/ZORA), providing insights into its formation. |
