Study of the Preparation of Peroxo Complexes of Ni(II), Mn(II) and Cr(III)

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Eight complexes of Ni(II), Mn(II) and Cr(III) were prepared. Five Ni(II) complexes, two Mn(II) complexes & one Cr(III) complex. All the complexes were characterized by elemental analysis, magnetic measurement, UV-vis and IR spectral studies. Complexes are [Ni(en)2](NO3)2 (1), [Ni(o-aminobenzoate)2] (2), [Ni(NCS)2(en)] (3), [Ni(SCN)2(en)] (4), [Ni(o-aminobenzoate)(O2)] (5), [Cr(en)2(O2)] (6), [Mn(o-aminobenzoate)3] (7), [Mn(o-aminobenzoate)2(O2)] (8). Formation of peroxo complexes take place, when both monodentate and bidentate ligand mixed with a metal salt followed by the addition of H2O2, but no peroxo complexes formed when only bidentate ligand presents. One reason might be that peroxo ligand could easily replace monodentate ligand SCN-, but not bidentate ligand ethylenediamine and o-aminobenzoic acid. In case of [Ni(NCS)2(en)] complex, it was observed that coordination of NCS- to Ni2+ changed from N and S after addition of H2O2 to [Ni(NCS)2(en)] complex.

Peroxo complexes; en = ethylenediamine; o-aminobenzoic acid