Cofacial dicobalt complex of a binucleating hexacarboxamide cryptand ligand.

A hexacarboxamide cryptand featuring appended polyether moieties is used as a binucleating ligand for two Co(II) centers, marking the first time cryptands have been used as hexaanionic N donors for metal coordination. A synthesis for the hexacarboxamide cryptand, culminating in a 23% yield high-dilution step and proceeding in 8% overall yield, is reported. The ligand is metalated using cobalt(II) acetate, and a solid-state structure is presented, revealing an intermetallic void over 6.4 A in length. The reactivity of this new type of cryptate is also probed; treatment of the dicobalt cryptate with potassium cyanide at elevated temperature results in a bridging cyanide complex.