Cobalt-oxygen bonds, bond energies

Depending on the peroxide class, the rates of decomposition of organic peroxides can be enhanced by specific promoters or activators, which significantly decrease the energy necessary to break the oxygen—oxygen bond. Such accelerated decompositions occur well below the peroxides normal appHcation temperatures and usually result in generation of only one usehil radical, instead of two. An example is the decomposition of hydroperoxides with multivalent metals (M), commonly iron, cobalt, or vanadium ... 

The inner-sphere reductions of [Co(NH3)5(SCONHR)] and [Co(NH3)5 (OCSNHR)] by Gr involve attack at the remote oxygen and sulfur atoms, respectively, with a subsequent isomerization of the 0-bonded ehromium(III) product in the former reaction. The unusually rapid reactions of the S-bonded cobalt(III) complexes are attributed to a structural tran -effect on the Co—N bond length, reducing the reorganization energy needed to form the transition state. A kinetic study of the Cr reduction of [Co(NH3)5(pyruvate)] reveals that the rate of reduction is dependent on the nature of pyruvate ligand, with the keto form about 400 times as reactive as the hydrated form. An inner-sphere mechanism has be postulated for the Cr reduction of [Co(NH3)5(pyridine N-oxide)] on the basis of the rate and activation parameters. The outer-sphere Cr reduction of [Co(sepulchrate)] is catalyzed by halide ions, with the ion-pair formation constants for [Co(sep), estimated to be 5.5, 2.3, and 1.7 M" for Cl", Br", and I", respectively. ... 

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