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Abstract
A number of transition-metal complexes are known to react with molecular oxygen in a reversible manner. The nature of the oxygen-
ation process is dependent upon both the metal and structure of the coordinating ligand (1, 2). Among the compounds which are known to react with oxygen are cobalt(II) porphyrins, cobalt(II) Schiff base complexes and Vaska-type complexes of iridium and other
metals (1, 2, 3). The Vaska-type complexes differ from the other complexes in both the structure of the oxygen adduct and their
chemical behavior and will not be discussed. The cobalt(II) Schiff base complexes are of special interest since they form both
a monomeric oxygen adduct, Co(II) SB-02, and a dimeric species in which two cobalt atoms are linked by an oxygen molecule, Co(II) SB-02-Co(II)SB(1). The formation constants for the monomeric adducts of the cobalt(II) Schiff base complexes are smaller than those observed for biological oxygen carriers such as hemoglobin. However, these formation constants are much larger than those observed for other synthetic oxygen carriers (1).
