The role of metal ions in oxygen activation

The reaction of oxygen with a common organic molecule is a spin-forbidden process catalyzed by transition metal ions. Some reactions of this type were proved to be trace metal catalyzed. It is therefore reasonable to assume that all reactions of molecular oxygen with organic molecules are induced by trace metals; in the absolute absence of transition metal ions these reactions would not proceed at all. Based on detailed studies of two well known oxygen reactions the mechanism of trace metal catalysis was formulated. The experimental results are consistent with the conception that transition metal ions associate with all species present in the system to form complexes or clusters of various composition and stability. Some of them are redox reactive and represent true intermediates of the catalyzed reaction.