Manganese complexes redox potentials

Following general trends in the transition metal series the redox potentials of complexes of the third row element rhenium are lower than those of manganese and (to a smaller extent) techne-... 

In the CV of [MnIV(LMe2)]+, this reversible Mn(I V)/Mn(III) one-electron transfer is observed at Em = -0.26 V vs Fc+/Fc. All other tris(phenolato)manganese complexes display this process at a similar redox potential. At more negative potentials, the Mn(III)/Mn(II) couple gives rise to a reversible one-electron reduction wave atEm —0.87 V, Eq. (10). 

A high content of linolenate in the thylakoid membranes would, most probably, make them more fluid and also provide a medium of low dielectric constant. In this medium, the electron-transport chains that are inhibited by water can function well.384-386 It was found that photoreduction of cytochrome C is increased by the addition of MGDG and DGDG.387 A complex that contained 12% of manganese, DGDG, and a flavine was isolated from a variety of leaves388 this was found to have a high redox potential, and thus, it may participate as an oxidizer. 

Electron transfer from the substrates to 02 proceeds by a redox cycle that consists of copper(II) and copper(I). The high catalytic activity of the copper complex can be explained as follows (1) The redox potential of Cu(I)/Cu(II) fits the redox reaction. (2) The high affinity of Cu(I) to 02 results in rapid reoxidation of the catalyst. (3) Monomers can coordinate to, and dissociate from, the copper complex, and inner-sphere electron transfer proceeds in the intermediate complex. (4) The complex remains stable in the reaction system. It may be possible to investigate other catalysts whose redox potentials can be controlled by the selection of ligands and metal species to conform with these requisites several other suitable catalysts for oxidative polymerization of phenols, such as manganese and iron complexes, are candidates on the basis of their redox potentials. 

Abstract This chapter discusses the electronic absorption spectra and electrochemistry of phthalocyanine complexes which are redshifted to 730nm and beyond. These are mainly manganese phthalocyanine derivatives and phthalocya-nines containing sulfur substituents. The chapter concentrates mainly on the work done during the last 10 years. There are 96 references quoted and three detailed tables on the electronic absorption spectra, redox potentials, and analytes that are electrocatalyzed using manganese and titanium phthalocyanine complexes. 

The macrobicyclic 3d-metal aza-capped l,3pn-sarcophaginates were studied by voltammetry. In contrast to sepulchrates and sarcophaginates, these complexes should favour to some degree the adoption of low oxidation states (+2 and +1). The oxidation waves are observed in DMF at 1380, 820, 227, 1180, and 1220 mV us SCE, respectively, for manganese, iron, cobalt, nickel, and copper complexes. The dependence of redox potentials on the number of d-electrons is the same as for [MCsar)] " " couple redox potentials. 

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