Issue 27, 2022

Fluorinated click-derived tripodal ligands drive spin crossover in both iron(ii) and cobalt(ii) complexes

Abstract

Control of the spin state of metal complexes is important because it leads to a precise control over the physical properties and the chemical reactivity of the metal complexes. Currently, controlling the spin state in metal complexes is challenging because a precise control of the properties of the secondary coordination sphere is often difficult. It has been shown that non-covalent interactions in the secondary coordination sphere of transition metal complexes can enable spin state control. Here we exploit this strategy for fluorinated triazole ligands and present mononuclear CoII and FeII complexes with “click”-derived tripodal ligands that contain mono-fluorinated benzyl substituents on the backbone. Structural characterization of 1 and 2 at 100 K revealed Co–N bond lengths that are typical of high spin (HS) CoII complexes. In contrast, the Fe–N bond lengths for 3 are characteristic of a low spin (LS) FeII state. All complexes show an intramolecular face-to-face non-covalent interaction between two arms of the ligand. The influence of the substituents and of their geometric structure on the spin state of the metal center was investigated through SQUID magnetometry, which revealed spin crossover occurring in compounds 1 and 3. EPR spectroscopy sheds further light on the electronic structures of 1 and 2 in their low- and high-spin states. Quantum-chemical calculations of the fluorobenzene molecule were performed to obtain insight into the influence of fluorine-specific interactions. Interestingly, this work shows that the same fluorinated tripodal ligands induce SCO behavior in both FeII and CoII complexes.

Graphical abstract: Fluorinated click-derived tripodal ligands drive spin crossover in both iron(ii) and cobalt(ii) complexes

Supplementary files

Article information

Article type
Paper
Submitted
01 4月 2022
Accepted
13 6月 2022
First published
13 6月 2022

Dalton Trans., 2022,51, 10507-10517

Fluorinated click-derived tripodal ligands drive spin crossover in both iron(II) and cobalt(II) complexes

M. Nößler, D. Hunger, N. I. Neuman, M. Reimann, F. Reichert, M. Winkler, J. Klein, T. Bens, L. Suntrup, S. Demeshko, J. Stubbe, M. Kaupp, J. van Slageren and B. Sarkar, Dalton Trans., 2022, 51, 10507 DOI: 10.1039/D2DT01005D

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements