Bis-Semiquinonate Copper Complexes with 4,4′-Bipyridine. Coordination Sphere Dynamics

We studied the reactions of sterically hindered bis-semiquinonates of copper(II) with 4,4′-bipyridine. Coordination polymer consisting of metallamacrocyclic binuclear copper(II) cage-like moieties bridged with 4,4′-bipyridine linkers was isolated in the reaction of copper(II) bis-semiquinonate metallamacrocycle with 4,4′-bipyridine. It is important that the initial and final metallamacrocycles in this reaction are different by the disposition of semiquinone units in the coordination surroundings of copper (II) ions. The transformation of one metallamacrocycle into another could only be achieved by a two-fold sequential cleavage of the metal-semiquinone bond.