Synthesis and characterization of a dinuclear manganese(III,III) complex with three phenolate ligands

Reiner Lomoth, Ping Huang, Jiutian Zheng, Licheng Sun, Leif Hammarström, Björn Åkermark, Stenbjörn Styring

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Abstract

A dinuclear manganese complex ([Mn2L(μ-OAc)2]PF6) has been synthesized, where L is the trianion of 2,6-bis{[(2-hydroxy-3,5-di-tert-butylbenzyl) (2-pyridylmethyl)amino]-methyl}-4-methylphenol, a ligand with three phenolate groups. The two pseudo-octahedrally coordinated Mn ions are bridged via the two bidentate acetate ligands and the 4-methylphenolate group of the ligand. We have characterized the complex with electrochemistry, spectroelectrochemistry and EPR spectroscopy. Electrochemically the Mn2III,III complex undergoes two metal-centered quasi-reversible one-electron reduction steps (E1/2 = 0.04 and -0.32 V vs. SCE). Reduction to the Mn2II,III state results in transformation into a modified complex with slightly different redox properties. One-electron oxidation (E1/2 = 0.96 V vs. SCE) affords the Mn2III,IV state while further one-electron oxidation (E1/2 = 1.13 V vs. SCE) presumably involves ligand oxidation. High valent Mn complexes involving MnIV or MnV centers are of particular interest as intermediates in catalytic water oxidation. The redox potentials of [Mn2L(μ-OAc)2]+ show the expected stabilization of higher manganese oxidation states compared with the related complex, [Mn2(bpmp)(μ-OAc)2]+.

Original languageEnglish
Pages (from-to)2965-2974
Number of pages10
JournalEuropean Journal of Inorganic Chemistry
Issue number11
DOIs
Publication statusPublished - Nov 1 2002

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Keywords

  • Ligand design
  • Manganese
  • Redox chemistry

ASJC Scopus subject areas

  • Inorganic Chemistry

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