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 with a variety of electron-rich and electron-poor organic substrates in order to compare their reactivities with those of other known metalloperoxide complexes. The peroxoiron(III) porphyrin complex was unreactive with electron-rich substrates such as tetramethylethylene, cyclohexene, triphenylphosphine, or butyllithium but was quite reactive with electron-poor substrates such as 2-cyclohexen-1-one and 2-methyl-1,4-naphthoquinone. The peroxomanganese(III) porphyrin complex was unreactive with these electron-poor olefins but did react with the strongly electron-deficient olefin tetracyanoethylene. The peroxotitanium(IV) porphyrin complex was unreactive with both electron-rich and electron-poor olefins, as well as butyllithium, but did quantitatively oxidize triphenylphosphine 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 complexes.
Sisemore
Marlene F.
MF
Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095.
Selke
Matthias
M
Burstyn
Judith N.
JN
Valentine
Joan Selverstone
JS