Convex and Concave Encapsulation of Multiple Potassium Ions by Sumanenyl Anions

Herein we report the novel complex
consisting of di- and tripotassiumsumanenide,
K7(C21H102–)2(C21H93–)·8THF
(2), which was prepared by the treatment of sumanene
(C21H12, 1) with excess K metal
in THF. The X-ray structural determination revealed unique self-assembly
of six potassium ions sandwiched by convex faces of two sumanenyl
trianions in addition to novel interaction involving all 15 carbon
atoms of three Cp-like moieties on the concave surface of the sumanenyl
bowls outside the sandwich. The unique structural features of 2 are rationalized with the help of DFT calculations.