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

Abstract

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 = ClO 4, PF 6). 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 Co II 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(ClO 4) 2 · 6H 2O leads to the isolation of [ Co 3 III , II , III { ( py ) C ( Me ) NO } 6 ] ( ClO 4 ) 2 .