Redox Reactions of a Dinuclear Manganese Complex – the Influence of Water

Abstract

The redox properties of the dinuclear manganese complex [Mn III,III 2 L(µ-OAc) 2 ] + (1) (where L is the trianion of the heptadentate ligand 2,6-bis{[(3,5-di-tert-butyl-2-hydroxybenzyl)-(2-pyridylmethyl)amino]methyl}-4-methylphenol) were studied in acetonitrile solutions containing different concentrations of water. Electrochemical reactions as well as reactions with different chemical and photochemical redox reagents were monitored, using a variety of analytical techniques, namely cyclic voltammetry, UV/Vis spectroelectrochemistry, and EPR spectroscopy. We found that even small concentrations of water influence the compound's redox behaviour significantly, especially the oxidation reactions. As a consequence, the presence of water reduces the overall potential span needed to reach the highest oxidation state observed

Redox‐State Dependent Ligand Exchange in Manganese‐Based Oxidation Catalysis

“…As part of an effort to understand the effect of water on the redox properties of synthetic OEC mimics, Kurz et al [97] studied the redox behaviour of the dinuclear complex With 5 m water, part of 13 re-reduced at 0.2 V, indicating the occurrence of a prior rapid equilibrium. Bulk electrolysis in the presence of water followed by UV/Vis absorption spectroscopy showed that one-electron reduction to the Mn II …”

“…[97] It was proposed that the product bears a di-μ-oxido or di-μ-oxido/hydroxido bridging motif in place of the μ-acetato ligands. The key attraction of multinuclear manganese complexes based on the 1,4,7-triazacyclononane (tacn) family of ligands is their thermodynamic stability and extensive redox and coordination chemistry.…”

Applications of the “nano to bulk” Mn oxides: Mn oxide as a Swiss army knife

“…They are also efficiently used by Nature for water oxidation process [93][94][95]. However, a few artificial Mn complexes display water-oxidizing activity, but Mn oxides are promising catalysts for water oxidation [88][89][90][91][92]. In 1968 Glikman [96], Shcheglova [96] and Shilov [97] introduced Mn oxides as water-oxidizing catalysts in the presence of cerium(IV) ammonium nitrate (Ce(IV)) as an oxidant.…”

“…Among different potential catalysts Mn complexes are very interesting because they are both cheap and environmentally friendly [86][87][88][89][90][91][92]. They are also efficiently used by Nature for water oxidation process [93][94][95].…”

Synthesis and electrochemistry of dimanganese(II) complexes of phenol-based dinucleating ligands with four methoxyethyl chelating arms

“…Various types of dimanganese complexes have been prepared as models of the biological systems [15], and the μphenoxo-bis(μ-carboxylato)dimanganese complex is one of the well-studied dimanganese complexes [16][17][18] …”