Electronic Structure of Three-Coordinate FeII and CoII β-Diketiminate Complexes

Alexandra L. Nagelski, Mykhaylo Ozerov, Majed S. Fataftah, J. Krzystek, Samuel M. Greer, Patrick L. Holland, Joshua Telser

Research output: Contribution to journalArticlepeer-review


The β-diketiminate supporting group, [ArNCRCHCRNAr], stabilizes low coordination number complexes. Four such complexes, where R = tert-butyl, Ar = 2,6-diisopropylphenyl, are studied: (nacnactBu)ML, where M = FeII, CoII and L = Cl, CH3. These are denoted FeCl, FeCH3, CoCl, and CoCH3 and have been previously reported and structurally characterized. The two FeII complexes (S = 2) have also been previously characterized by Mössbauer spectroscopy, but only indirect assessment of the ligand-field splitting and zero-field splitting (zfs) parameters was available. Here, EPR spectroscopy is used, both conventional field-domain for the CoII complexes (with S = 3/2) and frequency-domain, far-infrared magnetic resonance spectroscopy (FIRMS) for all four complexes. The CoII complexes were also studied by magnetometry. These studies allow accurate determination of the zfs parameters. The two FeII complexes are similar with nearly axial zfs and large magnitude zfs given by D = −37 ± 1 cm-1 for both. The two CoII complexes likewise exhibit large and nearly axial zfs, but surprisingly, CoCl has positive D = +55 cm-1 while CoCH3 has negative D = −49 cm-1. Theoretical methods were used to probe the electronic structures of the four complexes, which explain the experimental spectra and the zfs parameters.

Original languageEnglish (US)
Pages (from-to)4511-4526
Number of pages16
JournalInorganic Chemistry
Issue number10
StatePublished - Mar 11 2024
Externally publishedYes

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Inorganic Chemistry


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