METALLOPORPHYRIN PEROXO COMPLEXES OF IRON(III), MANGANESE(III), AND TITANIUM(IV) - COMPARATIVE-STUDIES DEMONSTRATING THAT THE IRON(III) COMPLEX IS EXTREMELY NUCLEOPHILIC

Peroxo Fe(III), Mn(III), and Ti(IV) porphyrin complexes were reacted w ith a variety of electron-rich and electron-poor organic substrates in order to compare their reactivities with those of other known metallo peroxide complexes. The peroxoiron(III) porphyrin complex was unreacti ve with electron-rich substrates such as tetramethylethylene, cyclohex ene, triphenylphosphine, or butyllithium but was quite reactive with e lectron-poor substrates such as 2-cyclohexen-1-one and 2-methyl-1,4-na phthoquinone. The peroxomanganese(III) porphyrin complex was unreactiv e with these electron-poor olefins but did react with the strongly ele ctron-deficient olefin tetracyanoethylene. The peroxotitanium(IV) porp hyrin complex was unreactive with both electron-rich and electron-poor olefins, as well as butyllithium, but did quantitatively oxidize trip henylphosphine to triphenylphosphine oxide. These results lead to the conclusion that the peroxo Fe(III) porphyrin complex is significantly more nucleophilic than the analogous Mn(III) and Ti(IV) complexes and than several well-known nucleophilic non-porphyrin peroxometal complex es.