Manganese complexes formation with hydrogen peroxide

Peroxidase forms a number of complexes with hydrogen peroxide. The activation mechanism of substrate molecules in the active center of peroxidase involves the formation of a ternary complex heme-H20-donor of electrons. The role of the iron ion consists of transferring electrons from the donor to the hydrogen peroxide molecule. Peroxidase is endowed, moreover, with the oxidase function which increases in the presence of divalent manganese ions. 

Catalysis of the decomposition by several metal ions has been reported . The order in peroxomonosulphate was found to be one, except for reaction with cobalt(II) and cerium(IV) (both second-order in the sulphate) and manga-nese(II) (half-order). Formation of a complex with cerium(IV) and peroxomonosulphate has been both asserted and denied . Catalysis by copper(II) is not significant unless manganese is also added, at least in the presence of some hydrogen peroxide ... 

A synthetic iron porphyrin with a thiolato ligand in the axial position has been oxidized by hydrogen peroxide in the presence of chloride. The shift of the Soret band from 408 nm to 404 nm might be due to the formation of a putative Fe OCl entity which can generate free HOCl after protonation. " The kinetic parameters of halide oxidation by a high-valent manganese-oxo porphyrin complex have been reported. ... 

More recently, the use of glyoxylic acid methyl ester hemiacetal as a cocatalyst was shown to afford an even more effective epoxidation catalyst, enabling high conversions with only a 30% excess of hydrogen peroxide. Interestingly, the corresponding cfs-diols were observed as by-products in many cases and a concerted mechanism via a manganese(III)-cfs-diol complex was proposed to explain their formation. 

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