Walter, M.; Hadjadj, S.E.; Trommer, C.; Torres, J.; Gördes, J.; Swerev, D.; Shinwari, T.; Lotze, C.; Luo, C.; Radu, F.; Tuczek, F.; Thakur, S.; Kuch, W.: Spin-Crossover in a Dinuclear Iron(II) Complex on Highly Oriented Pyrolytic Graphite: An X-Ray Absorption Spectroscopy Study. ChemPhysChem 26 (2025), p. e202401081/1-9
10.1002/cphc.202401081
Open Access Version
Abstract:
The spin-crossover (SCO) properties of the dinuclear complex [{Fe(H2B(pz)2)2}2 mu-(ac(bipy)2)] mathematical equation are studied as (sub)-monolayer and thin film deposited by an ultrahigh vacuum liquid-jet deposition technique on highly oriented pyrolytic graphite (HOPG) by X-ray absorption spectroscopy. A comparison of the SCO properties of thin films and a dropcast sample indicates that the spin-switching probability of the thin films is limited due to substrate–molecule interactions. The maximum percentage of molecules in the low-spin (LS) state observed for 0.7 and 1.8 monolayers (ML) is ≈43% at a temperature of 80 K in comparison to the dropcast sample where ≈66% of the complex is in the LS state. The similar switching properties of the dropcast sample as of a bulk powder sample confirm that the SCO properties are not affected by the presence of solvent necessary for deposition. The soft-X-ray-induced excited spin-state trapping (SOXIESST) effect is pronounced in all samples, although the light-induced high-spin (HS) fraction of the dropcast and the thin-film samples on HOPG is higher as compared to the HS fraction attained by SOXIESST, which confirms the sensitivity of the complex to light.