Synthesis and spectroscopic studies of new bis(N-1-hydroxy-2,6-di-tert-butylphenyl-salicylideneaminato)cobalt(II) complexes and their oxidation with PbO2

A series of new bis[N-(1-OH-2,6-di-tert-butylphenyl)salicylaldiminato]cobal t(II) complexes possessing one or two HO- and CH3O- substituents on the sal icylaldehyde moiety were prepared, and their spectroscopic properties as we ll as their oxidation with PbO2 were examined. ESR data indicate that oxida tion of the complexes produces stable phenoxyl radicals. All phenoxyl radic als have similar g-values and hyperfine coupling constants, which are influ enced very little by the substituents and by coordination. The experimental observations indicate that the Co(L-.x)(2) radicals are ligand-localized a nd that there is no notable contribution from the metal d-orbitals to the v alues of the g-factors. Satellite peaks from the C-13 nuclei in the aromati c ring were also observed. The ESR spectra of some of the complexes showed partial conversion of primary radicals to secondary paramagnetic species ex hibiting interaction with Co-59(I = 7/2) and N-14 nuclei.