Abstract

M. T. H. Tarafder*, N. Saravanan, Y. S. Yein and Gino Mariotto

Several novel dioxygen complexes of Fe(lll), Mo(VI) and W(VI) have been synthesized and characterized. A number of organic ligands, ranging from monodentate to tridentate, were used to form complexes having compositions of Fe[O2)(det);Cl] [Fe(O2)lL.CI.H20], [Mo(O)(O2)2(det)], H*[Mo(O)(O2)2L], [M(O)(O2)L'l and [M(O)(O2)2L'] [M=MO(VI) and W(VI); L=8-hydroxoquinolino, 2-picolinato, 2-aminophenoxido, 2-amino carboxylato; L=1,2-phenylenediamlne and o-phenanthroline; LM = triphenylphosphine oxide]. For peroxo complexes, the v(O-O) stretches were infrared active while the v(O=O) stretches of the superoxo complexes were only Raman active, because of apparent linearity of the M-O2" moieties, giving peaks at 1025-1035 cm-1,The complexes were all thermodynamically stable and that those with bidentate ligands were found to show oxygen transfer reactions to various organic and inorganic substrates. Comparative reactivities of the dioxygen complexes reveal for the first time that the superoxo complexes are stronger oxidants than the peroxo analogues. Mechanisms have been postulated.

2-aminophenoxido; Thermodynamically; Superoxo; Dioxygen

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