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 thetris-chelate Co(III) complexes of these oximes, which however could not be isolated in pure form.
