Type II P Dioxygen Complexes

We have seen, in the previous section (and section III.A), that cobalt (Salen) and its active derivatives normally form diamagnetic peroxo type I dioxygen adducts. However, a pyridine solution of Co(3-methoxy Salen) has been shown 137) to take up dioxygen with 1 1 (Co O2) stoichiometry it was found 137) that there was no significant IR absorption band, attributable to the 0—0 stretch, for the oxygenated complex, and this suggested that the dioxygen is symmetrically bonded in an unidentate manner, 

It is clear from the ESR studies that have been reported that the majority of workers favour the Co(III)-0 formulation for most mononuclear type II(/ ) dioxygen adducts. 

An X-ray photoelectron spectroscopic study (132) of some cobalt(II) Schiff base complexes and their dioxygen adducts finds that the cobalt core electron binding energies in 

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