Old ligands with new coordination chemistry: Linear trinuclear mixed oxidation state cobalt(III/II/III) complexes and their mononuclear “ligand” cobalt(III) complexes featuring 2-pyridyloximates

Reaction schemes involving 2-pyridyloximes, (py)C(R)NOH, CoII sources and counterions X− in various solvents lead to the new family of linear trinuclear clusters image (py = 2-pyridyl group; R = H, Me, Ph; X = ClO4, PF6). The outer metal centres are low spin, octahedral CoIII ions and are coordinated by three N,N′-bound 2-pyridyloximato ligands; each of these outer CoIII complexes acts as a tridentate chelating “ligand” to the central CoII ion, which adopts an octahedral geometry with six oxygen donor atoms. The CoIII “ligands” have been individually prepared and the reaction of [CoIII{(py)C(Me)NO}3] with Co(ClO4)2 · 6H2O leads to the isolation of image.