Structural studies of heptanuclear cobalt complexes and larger oligomers based on heptanuclear fragments

The structures of three heptanuclear cobalt cages supported by carboxylates and 6-chloro-2-pyridonate (chp) have been determined. The metal cores can be derived from a square-based pyramid, capped on one edge of the square base and on the neighbouring triangular face of the pyramid. Use of phthalate in a similar reaction results in a tridecanuclear cage which resembles a dimer of the heptanuclear cages, linked through the dicarboxylate ligands. In addition a heterometallic polymer is reported, where heptanuclear cobalt fragments are linked through sodium containing complexes to form a one-dimensional compound. Comparisons are made between these cages and previously reported structures which also involve pyridonate and carboxylate ligands. These indicate that all the cages can be derived from the structure of Co(OH)(2).