Tracking the HS-HS, HS-LS, and LS-LS States in the Spin Transition of a Dinuclear Fe(II) Complex by Broadband FTIR Spectroscopy
Highly resolved vibrational spectra of the mononuclear Fe(II) spin-crossover complex [Fe(bpz)<sub>2</sub>(bipy)]; (bpz = dihydrobis(pyrazolyl)borate) and its dinuclear counterpart [{Fe(bpz)<sub>2</sub>}<sub>2</sub>μ-(ac(bipy)<sub>2</sub>)] (ac(bipy)<sub>2</sub> = bridging ligand) are obtained by temperature-dependent far-infrared (FIR) spectroscopic measurements and assigned with the help of density functional theory (DFT) calculations. The experimental data confirm the high-spin (HS) state of the complexes at high temperature (≈ 200 K) and the low-spin (LS) state at 5 K. In the dimer, enhancement of otherwise absent vibrational modes at 335 cm<sup>-1</sup> and 504 cm<sup>-1</sup> around <i>T</i><sub>1/2</sub> reflects the presence of a mixed-spin HS-LS state during the course of the spin transition between HS-HS and LS-LS. The metastable HS state of the dinuclear complex resulting from light irradiation (532 nm) at 10 K results from a direct spin-state transition from LS-LS to HS-HS.
Authors
- Sangeeta Thakur (ORCID: https://orcid.org/0000-0003-4879-5650)
- Tarek Al Said (ORCID: https://orcid.org/0000-0002-9057-5451)
- W. Kuch (ORCID: https://orcid.org/0000-0002-5764-4574)
- Felix Tuczek (ORCID: https://orcid.org/0000-0001-7290-9553)
- K. Holldack (ORCID: https://orcid.org/0000-0003-3931-3971)
- Clara Trommer
- Eike F. Kuhlemann
- Marcel Walter (ORCID: https://orcid.org/0009-0003-4145-0358)
Institutions
- Helmholtz-Zentrum Berlin für Materialien und Energie (DE)
- Christian-Albrechts-Universität zu Kiel (DE)
- Institute of Inorganic Chemistry of the Slovak Academy of Sciences (SK)
- Freie Universität Berlin (DE)
Publication Details
- Journal
- The Journal of Physical Chemistry Letters
- Published
- 2025-12-05
- DOI
- https://doi.org/10.1021/acs.jpclett.5c03119
- Citations
- 1
- Primary Topic
- Magnetism in coordination complexes
- Type
- article
- Field-Weighted Citation Impact
- 0.43