Di- and tri-nuclear copper(II) metallocycles: Building blocks for supramolecular chemistry

The preparation of unsaturated neutral dinuclear and trinuclear metallocycles by employing bis-β-diketonato ligands was investigated. It was found that it was possible to exploit the coordinatively unsaturated copper (II) centers by treating them with nitrogen bases to form a variety of neutral five-coordinate adducts. The reaction of the first compound with copper(II) produces a neutral dinuclear metallocycle with coordinatively unsaturated metal centers while the reaction with an octahedral trivalent metal ion such as iron (III) produces discrete chiral triple helices. The reaction of the second compound with copper(II) produces coordinatively unsaturated trinuclear triangular species analogous to the dinuclear metallocycles. It was observed that extended discrete and polymeric species are expected to result if a difunctional nitrogen donor was treated with the copper(II) metallocycles.