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, Co-II sources and counterions X- in various solvents lead to the new family of linear trinuclear clusters [Co-3(III,II,III) (py)C(R)NO}(6)]X-2 (py = 2-pyridyl group; R = H, Me, Ph; X = ClO4, PF6). The outer metal centres are low spin, octahedral Co-III ions and are coordinated by three N,N'-bound 2-pyridyloximato ligands; each of these outer Co-III complexes acts as a tridentate chelating "ligand" to the central Coll ion, which adopts an octahedral geometry with six oxygen donor atoms. The Co-III "ligands" have been individually prepared and the reaction of [Co-III{(py)C(Me)NO}(3)] with CO(ClO4)(2) center dot 6H(2)O leads to the isolation of [Co-3(III,II,III){(py)C(Me)NO)(6)](ClO4)(2). (C) 2005 Elsevier B.V. All rights reserved.