Peroxo-centered macrocycle

In tetraazamacrocyclic Co(II) complexes, the formation of /<-peroxo-Co(III) complexes following coordination of O2 to Co(II) complexes can be suppressed if the macrocycle is functionalized to inhibit face-to-face approach of the Co(II) centers. The thermodynamic stabilities of complexes [(X)LCo] (X =SCN or Q", L = C-meso-5,7,7,12,14,14-hexamethyl-l,4,8,ll-tetraaza-cyclotetradecane) have been determined and the effects of the anion X on the rate of dioxygen binding have been studied by laser flash photolysis after the flash, there is an immediate bleaching of the solution at the absorbance wavelength of the complex, followed by a slower return of absorbance. Reestablishment of the equilibrium for SCN can be analyzed in terms of Eq. (4) to (6) an analogous sequence applies when the anion is Cl . 

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