Towards Iron(II) Complexes with Octahedral Geometry: Synthesis, Structure and Photophysical Properties

Autor: Mohamed Darari, Antonio Francés-Monerris, Bogdan Marekha, Abdelatif Doudouh, Emmanuel Wenger, Antonio Monari, Stefan Haacke, Philippe C. Gros
Jazyk: angličtina
Rok vydání: 2020
Předmět:
Zdroj: Molecules, Vol 25, Iss 24, p 5991 (2020)
Druh dokumentu: article
ISSN: 1420-3049
DOI: 10.3390/molecules25245991
Popis: The control of ligand-field splitting in iron (II) complexes is critical to slow down the metal-to-ligand charge transfer (MLCT)-excited states deactivation pathways. The gap between the metal-centered states is maximal when the coordination sphere of the complex approaches an ideal octahedral geometry. Two new iron(II) complexes (C1 and C2), prepared from pyridylNHC and pyridylquinoline type ligands, respectively, have a near-perfect octahedral coordination of the metal. The photophysics of the complexes have been further investigated by means of ultrafast spectroscopy and TD-DFT modeling. For C1, it is shown that—despite the geometrical improvement—the excited state deactivation is faster than for the parent pseudo-octahedral C0 complex. This unexpected result is due to the increased ligand flexibility in C1 that lowers the energetic barrier for the relaxation of 3MLCT into the 3MC state. For C2, the effect of the increased ligand field is not strong enough to close the prominent deactivation channel into the metal-centered quintet state, as for other Fe-polypyridine complexes.
Databáze: Directory of Open Access Journals
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