Spin States, Bonding and Magnetism in Mixed-Valence Iron(0)-Iron(II) Complexes

Daniel Kim, Daniel W.N. Wilson, Majed S. Fataftah, Brandon Q. Mercado, Patrick L. Holland

Research output: Contribution to journalArticlepeer-review

Abstract

“Xenophilic” complexes offer metal-metal bonds between disparate metal sites, but the nature of the metal-metal bonding is often unclear. Here, we describe two novel complexes with unsupported Fe−Fe bonds, LxFe−Fp (LX = β-aldiminate or β-diketiminate; Fp = Fe(CO)2Cp), that offer insight into Fe−Fe bonding. Mössbauer, magnetism, and DFT analysis indicate that the most accurate electronic structure description is LFeII←Fe0(CO)2Cp, in which the Fe(CO)2Cp is low-spin iron(0) and acts as an X-type ligand toward the high-spin iron(II) of the LFe fragment. This largely electrostatic interaction has a bond order of only 0.5. The three-coordinate high-spin iron(II) site has large zero-field splitting, and in addition its Mössbauer parameters can be used to rank the Fp “metalloligand” as a donor; it is nearly as strong a donor as phosphides and alkyls.

Original languageEnglish (US)
Article numbere202104431
JournalChemistry - A European Journal
Volume28
Issue number11
DOIs
StatePublished - Feb 19 2022
Externally publishedYes

Keywords

  • Iron
  • magnetism
  • metal-metal bonds
  • xenophilic complexes

ASJC Scopus subject areas

  • Catalysis
  • General Chemistry
  • Organic Chemistry

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