Organodioxygen Complexes of Some Low- and High- Valent Metal Ions and Their Oxygen Transfer Reactions

M. T. H. Tarafder¹*, S. K. Tan¹, K. H. Su¹ and N. Saravanan², G. Mariotto²,

¹Department of Chemistry, Faculty of Science and Environmental Studies University Putra Malaysia, 43400 Serdang, Selangor (Malaysia) ²Department of Physics, University of Trento, Trento (Italy)

Some dioxygen complexes of cobalt(II), zinc(II), antimony(V), tantalum(V) and niobium(V) of the compositions [M(O)2LCl(H2O)n], [M(O2)L(H2O)n], [M(O2)L2(H2O)n]Cl, [M’(O2)2LCl] and [M’(O2)2L’Cl], [M=Co(II), Zn(II); n=0 or 1; M’=Sb(V), Nb(V) and Ta(V); L = 1,2-phenylenediamine, 2-aminopyridine, O-phenanthroline, 1,4-diaminobutane diethylenetriamine, L'= pyridine-N-oxide, triphenylphospine] have been synthesized and characterized by elemental analyses, conductivity measurements, IR and Raman spectral studies. Comparison of the IR and Raman spectra indicate that the dioxygens are bonded in an end-on, superoxo-type manner, in the cobalt and zinc complexes, (1), (2) and (5), giving n1(O=O) stretching modes at 1125-1150cm-1, while they are side-on peroxo species in some other zinc, antimony, niobium and tantalum complexes, (3), (4), (6)-(14), with n1(O=O) bands at 816-868 cm-1. The effect of dp-pp bonding in the M-O2- moiety in the superoxo complexes makes them stronger oxidants than the peroxo analogues toward triphenylphosphine.

Organodioxygen complexes; superoxo complexes and peroxo species