Cobalt-dioxygen complexes, aqueous studies

The photochemistry of the complex [(trien)Co(/i-OH 02)Co(trien)] has been studied in basic aqueous solution. The photoinduced cobalt(II)-trien complexes, [Co(trien)(OH2)2] and [Co(OH)trien(OH2)], react with dioxygen in basic solution to give the intermediates [(OH)(trien) Co-02-Co(trien)(OH2)] " and [(OH)(trien)Co-02-Co(trien)(OH)]2+, which are transformed reversibly into the starting complex. The transient absorption spectra of the monobridged //-peroxo complexes, which have an absorption maximum near 313 nm, were measured by a flash photolysis method. Rate constants for the reaction of the cobalt(II )-trien complexes with dioxygen were also determined as a function of pH, and are compared with the constants obtained using stopped flow methods. 

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