Mechanism of the reaction of 1,1′-diethylferrocene and decamethylferrocene with peroxides in organic solvents

Kinetic relationships of oxidation of 1,1'-diethylferrocene and decamethylferrocene with peroxides ROOR (R = H, t-C4H9) in organic solvents were studied and the composition of oxidation products was established. It is shown that reactivity of (C5H4C2H5)(2)Fe is significantly lower than that of Cp*Fe-2 [Cp* = eta(5)-C-5(CH3)(5)] which is seen from the ability of the first metal complex to undergo oxidation with a notable rate only in the presence of Bronsted acids, whereas the second substance is oxidized both in the presence and in the absence of these acids. Two possible mechanisms of oxidation of metal complexes in the presence of strong acids are discussed. One of them is based on the ability of ferrocene to fast and equilibrium protonation with the formation of Cp2Fe+-H structure. Another one considers the ability of metal complexes to coordinate peroxides with the formation of weakly bound charge transfer complexes of the composition Cp2Fe delta+center dot ROOR delta-. The possibility of their formation is confirmed by the oxidation of Cp2Fe with hydroperoxides in the absence of acids.