The synthesis, characterization and dioxygen affinity of pillared cobalt complexes derived from the glyoximato ligand family

Dioxime platforms for cobalt dioxygen carriers are extended to those having diphenylboron linkages in the macrocycle by replacing the protons of the bis(alpha-dioxime) parent ligand systems, in analogy to those having BF2+ linkages. The electron releasing character of the BPh(2)(+) as compared to BF2+, is evident in greatly increased dioxygen affinities. Finer tuning of the dioxygen affinity is achieved by replacing the methyl groups of the dimethylglyoximato groups with the diphenyl derivatives. The steric demands of the phenyl groups also inhibit autoxidation of these new dioxygen carriers.