Five binary Schiff bases and their dioxygen affinity Co(II) complexes were synthesized from 2-hydroxy-3-methoxy-5-methylbenzaldehyde and diamines such as ethylenediamine, 1,2-propylenediamine, 2,3-dimethyl-2, 3-butylenediamine, 1,3-propylenediamine and 1,2-phenylenediamine. The adduction constants of these complexes to dioxygen (O2) were measured in diglyme solution with 4-methylpyridine as an axial ligand. Their affinity to O2 was influenced remarkably by rigidity of the diamine-Co(II) chelating ring in the complexes.

Key words: BENZALDEHYDE P, OXYGEN, COBALT COMPLEX, SCHIFF BASE, PROPANEDIAMINE, DIAMINE, BENZENEDIAMINE, ETHANEDIAMINE P, BUTANEDIAMINE