Nara Women’s University, Japan
Critical Factors in Determining the Reactivity of Hypochlorite Adducts of Metal Complexes
The reactions of metal centers with terminal oxidants (XO) are key steps to generating reactive high-valent metal oxo species in various metal catalyzed oxidation reactions and metalloenzymes. The reactions initially form terminal oxidant adducts of metal complexes, followed by the formation of the high-valent metal oxo species by the cleavage of the O–X bonds of the metal-bound terminal oxidants. Because of their biological significance, the terminal oxidant adducts of metal complexes have been prepared from the reactions of various metal complexes with terminal oxidants such as hydrogen peroxide, alkyl hydroperoxides, iodosylarenes, and peracids. Electronic structure and reactivity of these terminal oxidant adducts have also been studied by various spectroscopic methods. In contrast, hypochlorite (OCl–) adducts of metal complexes have not been characterized although hypochlorite has been used as a terminal oxidant in many catalytic oxidation reactions. In addition, the hypochlorite adducts of iron porphyrin complexes have also been proposed as the key intermediates in catalytic cycles of heme enzymes such as chloroperoxidase and myeloperoxidase. Recently, we succeeded in the preparation and characterization of hypochlorite adducts of iron(III) porphyrin and manganese salen complexes.1-3 In this presentation, I will present recent results on the reactivity of the hypochlorite adduct complexes.