Unusual Magneto-Structural Features of the Halo-Substituted Materials [FeIII(5-X-salMeen)2]Y: a Cooperative [HS-HS]↔[HS-LS] Spin Transition

Mariam A. Al-Azzani, Faizah Al-Mjeni, Ryoji Mitsuhashi, Masahiro Mikuriya, Imaddin A. Al-Omari, Craig C. Robertson, Eckhard Bill, Musa S. Shongwe*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

11 Citations (Scopus)


X-ray structures of the halo-substituted complexes [FeIII(5-X-salMeen)2]ClO4 (X=F, Cl, Br, I) [salMeen=N-methyl-N-(2-aminoethyl)salicylaldiminate]at RT have revealed the presence of two discrete HS complex cations in the crystallographic asymmetric unit with two perchlorate counter ions linking them by N−Hamine⋅⋅⋅Operchlorate interactions. At 90 K, the two complex cations are distinctly HS and LS, a rare crystallographic observation of this coexistence in the FeIII-salRen (R=alkyl) spin-crossover (SCO) system. At both temperatures, crystal packing shows dimerization through C−Himine⋅⋅⋅Ophenolate interactions, a key feature for SCO cooperativity. Moreover, there are noncovalent contacts between the complex cations through type-II halogen-halogen bonds, which are novel in this system. The magnetic profiles and Mössbauer spectra concur with the structural analyses and reveal 50 % SCO of the type [HS-HS]↔[HS-LS] with a broad plateau. In contrast, [FeIII(5-Cl-salMeen)2]BPh4⋅2MeOH is LS and exhibits a temperature-dependent crystallographic phase transition, exemplifying the influence of lattice solvents and counter ions on SCO.

Original languageEnglish
Pages (from-to)4766-4779
Number of pages14
JournalChemistry - A European Journal
Issue number21
Publication statusPublished - Apr 9 2020
Externally publishedYes


  • crystallographic phase transition
  • electronic and electrochemical processes
  • ferric spin crossover
  • noncovalent interactions
  • spin-transition plateau

ASJC Scopus subject areas

  • Catalysis
  • Organic Chemistry


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