Magnetic and catalytic properties of new Schiff base dinuclear complexes

This paper reports the catalytic properties of "porphyrin-like" Schiff base mononuclear complexes MH2L {M=Mn(II), Fe(III)Cl, Cr(III)Cl, Cu(II), Co(II), Ni(II), Zn(II); L=bis[N, N'-ethylene-2, 2'-(phenylmethylene)bis(3,4-dimethylpyrrole-5-aldimino)]} and dinuclear complexes MnML [M=Mn(II), Fe(III)Cl, Cr(III)Cl, Cu(III), Co(II), Ni(II), Zn(II)] for cyelohexane monooxygenation with PhIO and magnetic properties of the dinuclear complexes. The magnetic investigations (4 similar to 300 K) of the dinuclear complexes revealed that their antiferromagnetic spin exchange with J ranged from -10.49 to -0.482 cm(-1) except MnZnL and antiferromagnetle spin exchange decreased in the following order: Mn-II-Cu-II > Mn-II-Ni-II > Mn-II-Mn-II > Mn-II-Fe-III > Mn-II- Co-III > Mn-II-Cr-III. The results of catalyzed oxidation of cyclohexane indicated that the catalytic property of the dinuclear complex was better than that of the corresponding mononuclear complex. It was found that there was the synergism decreased in the order: Mn-Fe > Mn-Cr > Mn-Cu > Mn-Mn > Mn-Co > Mn-Ni > Mn-Zn. It seems that this synergism increases with the increase of the number of unpaired d electrons and the magnetic exchange between the two metals in these dinuclear complexes.