Synthetic and structural studies of cobalt-pivalate complexes

The synthesis and characterisation of a range of cobalt pivalate cage complexes are reported. The cages include: a dinuclear Co-II complex; an oxo-centred Co-III triangle; tetranuclear Co-II heterocubanes and butterflies; tetranuclear heterovalent cobalt butterflies and hexanuclear edge-sharing bitetrahedra; heterovalent penta-, hexa- and hepta-nuclear cages based on {M4O4} heterocubane cores; and a tetradecanuclear cage based on heterocubanes sharing edges and vertices. Spectroscopic studies suggest that some of these cores are retained in solution, but that only in the Co-III triangle is the structure including ligands retained. A scheme is proposed to account for the many structures observed, which may be applicable to other polymetallic cage complexes.