Catalytic oxidations using cobalt(II) complexes - Advances in Catalytic Activation of Dioxygen by Metal Complexes - page 268

1,4,7,10-tetraazacyclododecane and 1,4,8,11-tetraazacyclotridecane has
recently been studied 11 .
The general features of oxygenation equilibria and autoxidation involving
cobalt-based lacunar cyclidene dioxygen carriers have been extensively
studied by Busch and coworkers with special reference to dioxygen affinities
and their correlation with structural features 3,4,12,13 . Lacunar systems have
considerable activities for reversible dioxygen binding in their cavities under
ambient conditions.

The autoxidation of dioxygen carriers may involve both metal-centered
oxidation to and ligand oxidation, leading to ligand destruction.
Typical ligand oxidations involve oxidative dehydrogenation of
to imine bonds as in the case of cobalt (II) complexes of Pydien 14 , and
to carbonyl group oxidations in macrocyclic chelates 15,16 :