Spin Transition in a Manganese(III) Porphyrin Cation Radical, Its Transformation to a Dichloromanganese(IV) Porphyrin, and Chlorination of Hydrocarbons by the Latter.
Chemical oxidation of (TMP)Mn(III)(Cl) (TMP = the tetramesitylporphyrinato dianion) by Fe(ClO(4))(3) leads to the porphyrin-oxidized product (TMP(*)(+))Mn(III)(ClO(4))(2). Magnetic measurements and EPR spectroscopy show that the total spin of the complex changes from S = (5)/(2) at high temperature to S = (3)/(2) at low temperature. Ligand exchange of the perchlorato ligands in (TMP(*)(+))Mn(III)(ClO(4))(2) by chloride anions is accompanied by a change of the oxidation site from porphyrin to metal, resulting in (TMP)Mn(IV)(Cl)(2). This high-valent-metal complex can effect chlorine atom transfer to olefins, as well as to dimedone and chlorodimedone, natural substrates of chloroperoxidases.
Kaustov
Lilia
L
Department of Chemistry, Technion-Israel Institute of Technology, Haifa 32000, Israel, and Department of Physics, Laboratory of Magnetic Resonance, Ben-Gurion University of the Negev, Beer Sheva 84105, Israel.
Tal
Merav E.
ME
Shames
Alexander I.
AI
Gross
Zeev
Z