Electron paramagnetic resonance studies of some cobalt amine oxygen adducts in zeolite Y

The reversible uptake of oxygen by cobalt(I1) complexes in solution has been extensively studied, particularly with a view to understanding the bonding and activation of oxygen in biological oxygen carriers.' Several recent electron paramagnetic resonance (EPR) studies have shown that transition metal cations in the faujasite-type zeolite Y can form well-defined complexes with added ligands within the large cavities of the zeolite framework, which are approximately 13 A in diameter. Cobalt oxygen adducts formed within the zeolite structure may be expected to show interesting differences in properties from those of the analogous adducts
in solution. Our study of these adducts in zeolite Y has also been prompted by the possibility of activating oxygen in a heterogeneous system.
A preliminary account has been given of the formation of the monomeric oxygen adduct of a cobalt(I1) ammonia complex in zeolite Y.5 This paper describes a more detailed study of the formation and stability of oxygen adducts of cobalt with ammonia, methylamine, and n-propylamine as ligands. It is shown that with ammonia and methylamine both monomeric 1:l and dimeric 1:2 oxygen adducts can be formed, whereas with n-propylamine only the 1:l adduct is observed.