Dioxygen Reactivity-Structure Correlations in Manganese (2) Complexes

摘要

The utilization of dioxygen in biological systems and organic syntheses is of the utmost importance. A feature shared by almost all biological dioxygen reactions, including the transport of 02, is the involvement of metal ions via complexation and activation. Some examples are cytochromes, superoxide dismutase, hemoglobin and myoglobin. The metals involved usually are manganese, iron and copper. Manganese, for example, has been implicated as a possible dioxygen evolving agent in photosynthesis. Calvin postulated that a Mn -O-O-Mn linkage could be important in the final dioxygen evolution step. Another aspect of dioxygen manganese reactivity is the well documented advantage of using manganese in some form as a catalyst to effect various organic oxidations. Manganese is known to oxidize alkylbenzenes, alcohols, carboxylic acids, phenols and ethers. MnO2 has proved to be a highly selective heterogeneous oxidant for amines, hydrazines, hydrocarbons, heterocyclic compounds and other natural products. Evidence has been presented in certain cases that an oxygen atom can be directly transferred from the oxidant to the substrate.