μ-Peroxodicobalt(III) complexes containing aromatic ligands

Abstract

A series of new μ-peroxodicobalt(III) complexes have been prepared and characterized. Studies of the chemical and physical properties of these complexes were carried out using IR, electronic and NMR spectroscopy along with conductivity, magnetic susceptibility and thermogravimetric measurements. The complexes [Co 2(dpk·dien) 2 (dpk·H 2O)O 2] (ClO 4) 4·H 2O, [Co 2(dpk) 4(py) 2O 2](ClO 4) 4·4H 2O, [Co 2(dpk·H 2O 4(py) 2O 2] (ClO 4) 4, and [Co 2(dpk) 2(terpy) 2O 2](ClO 4) 4 were prepared by bubbling oxygen through a solution containing Co(NO 3) 2, NaClO 4, and the appropriate ligand mixture. Electronic spectral studies are consistent with the formulation as binuclear peroxo complexes. Thermogravimetric studies reveal the stoichiometric loss of O 2 and H 2O below 100°C. The auxiliary ligands, pyridine (py), diethylenetriamine (dien) and terpyridine (terpy) are lost at higher temperatures. Molar conductance of these complexes is indicative of a 4:1 electrolyte while magnetic susceptibility measurements indicate the diamagnetic character of the above four complexes. Three additional complexes of Co(II) containing di-2-pyridyl ketone (dpk) and terpy were prepared to compare spectral changes upon oxygenation.