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 angstrom 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.