Molecular Insights into the Ligand-Based Six-Proton- and Six-Electron-Transfer Processes Between Tris-ortho-Phenylenediamines and Tris-ortho-Benzoquinodiimines

Takeshi Matsumoto, Risa Yamamoto, Masanori Wakizaka, Akinobu Nakada, Ho Chol Chang

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)

Abstract

The global demand for energy and the concerns over climate issues renders the development of alternative renewable energy sources such as hydrogen (H2) important. A high-spin (hs) FeII complex with o-phenylenediamine (opda) ligands, [FeII(opda)3]2+ (hs-[6R]2+), was reported showing photochemical H2 evolution. In addition, a low-spin (ls) [FeII(bqdi)3]2+ (bqdi: o-benzoquinodiimine) (ls-[0R]2+) formation by O2 oxidation of hs-[6R]2+, accompanied by ligand-based six-proton and six-electron transfer, revealed the potential of the complex with redox-active ligands as a novel multiple-proton and -electron storage material, albeit that the mechanism has not yet been understood. This paper reports that the oxidized ls-[0R][PF6]2 can be reduced by hydrazine giving ls-[FeII(opda)(bqdi)2][PF6]2 (ls-[2R][PF6]2) and ls-[FeII(opda)2(bqdi)][PF6]2 (ls-[4R][PF6]2) with localized ligand-based proton-coupled mixed-valence (LPMV) states. The first isolation and characterization of the key intermediates with LPMV states offer unprecedented molecular insights into the design of photoresponsive molecule-based hydrogen-storage materials.

Original languageEnglish
Pages (from-to)9609-9619
Number of pages11
JournalChemistry - A European Journal
Volume26
Issue number43
DOIs
Publication statusPublished - 2020 Aug 3
Externally publishedYes

Keywords

  • iron
  • N ligands
  • oxidation
  • reduction
  • valency

ASJC Scopus subject areas

  • Catalysis
  • Organic Chemistry

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