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

Abstract

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