Imino- and bis-imino-pyridines with N-ter-butyl-N-aminoxyl group: synthesis, oxidation and use as ligand towards M2+ ( Mn, Ni, Zn) and Gd3+

Imino- and bis-iminopyridine ligands bearing N-ter-butylhydroxy groups were synthesized by the condensation reaction between a N-ter-butylhydroxy substituted aniline and 2-formylpyridine, 2-acetylpyridine and 2,6-bis-acetylpyridine. The N-ter-butylaminoxy radicals obtained after oxidation using PbO2 or Ag2O were studied by EPR spectroscopy in solution. Indeed, complete decomposition was observed during isolation of these radical derivatives. The N-ter-butylhydroxy substituted ligands obtained were complexed with Mn2+, Ni2+, Zn2+ and Gd3+ salts; the obtained complexes were characterized and oxidized to give the aminoxy analogs, which were studied using IR, UV and EPR spectroscopies.