Host–Guest Interactions: Design Strategy and Structure of an Unusual Cobalt Cage That Encapsulates a Tetrafluoroborate Anion

Stuck in the middle: Supramolecular host–guest cages of general formula [BF4⊂(RCN)2Co2L4](BF4)3 with L being a di(benzimidazole)-1,4-phenylene derivative (R=Me, Et, Ph) have been prepared. An encapsulated BF4− anion (B yellow, F pale green; see structure) is locked firmly inside the cage and plays a pivotal role as a template around which the CoII ions (gray) and L ligands (ball-and-stick representation) self-assemble.