Abstract: The kinetic properties and the substituent effects of the oxidations of new Schiff base complexes Mn₂L{L=bis[ N,N'-alkylene-2,2'-(arylmethylene)bis(3,4-dimethylpyrrole-5-aldimino)]} with PhIOwere studied by UV-Vis. The results showed that the oxidations are the first order for the complexes. We also found that being contrary to the electron donating groups, the electron withdrowing groups on the phenyl groups or/ and the phenylene groups of the complexes could increase their stabilities; with respect to the antioxidation against PhIO, the substituent effects on the phenylene groups of the complexes are greater than those on the phenyl groups; there are the linear relationships between the reaction kinetic constant k and the substituent constant σ:-lg k=0.5215 σ + 1.326 for the complexes with substituents on the phenyl groups and -lg k=0.8271[( σ_m+ σ_p)/2]⁺1.506 for the complexes with substituents on the phenylene groups.

Key words: Schiff base complexes, Oxidation, Reaction kinetics, Substituent effects