EPR OF THE CO(II) COMPLEXES OF PHENANTHRAQUINONEDIOXIME AND BENZOQUINONEDIOXIME - FORMATION OF DIOXYGEN ADDUCTS IN THE SOLID-STATE

Cobalt(II) complexes of 9, 10-phenanthrenedionedioxime (pqdH(2)) and b enzoquinonedioxime (bqdH(2)) and the doped sample, Co(pqdH)(2)/Ni(pqdH )(2) were prepared and investigated by EPR. The EPR parameters, especi ally the small hyperfine splitting values, reveal the presence of oxyg en adduct in the concentrated (undoped) samples, while the dilute (dop ed) sample has parameters corresponding to a (2)A(1)(\z(2)]) ground st ate. It is proposed that the oxygen adducts are formed as intermediate s, leading ultimately to the tris-chelate Co(III) complexes of these o ximes, which however could not be isolated in pure form.