EPR of the Co(II) complexes of phenanthraquinonedioxime and benzoquinonedioxime. Formation of dioxygen adducts in the solid state

Abstract

Cobalt(II) complexes of 9, 10-phenanthrenedionedioxime (pqdH2) and benzoquinonedioxime (bqdH2) and the doped sample, Co(pqdH)2/Ni(pqdH)2 were prepared and investigated by EPR. The EPR parameters, especially the small hyperfine splitting values, reveal the presence of oxygen adduct in the concentrated (undoped) samples, while the dilute (doped) sample has parameters corresponding to a2A1(|z2 > ) ground state. It is proposed that the oxygen adducts are formed as intermediates, leading ultimately to the tris-chelate Co(III) complexes of these oximes, which however could not be isolated in pure form. © 1995 Indian Academy of Sciences.