Issue 23, 2024

Spin crossover in dinuclear iron(ii) complexes bridged by bis-bipyridine ligands: dimer effects on electronic structure, spectroscopic properties and spin-state switching

Abstract

Inspired by the well-studied mononuclear spin crossover compound [Fe(H2B(pz)2)2(bipy)], the bipyridine-based bisbidentate ligands 1,2-di(2,2′-bipyridin-5-yl)ethyne (ac(bipy)2) and 1,4-di(2,2′-bipyridine-5-yl)-3,5-dimethoxybenzene (Ph(OMe)2(bipy)2) are used to bridge two [Fe(H2B(pz)2)2] units, leading to the charge-neutral dinuclear iron(II) compounds [{Fe(H2B(pz)2)2}2 μ-(ac(bipy)2)] (1) and [{Fe(H2B(pz)2)2}2 μ-(Ph(OMe)2(bipy)2)] (2), respectively. The spin-crossover properties of these molecules are investigated by temperature-dependent PPMS measurements, Mössbauer, vibrational and UV/Vis spectroscopy as well as X-ray absorption spectroscopy. While compound 1 undergoes complete SCO with T1/2 = 125 K, an incomplete spin transition is observed for 2 with an inflection point at 152 K and a remaining high-spin fraction of 40% below 65 K. The spin transitions of the dinuclear compounds are also more gradual than for the parent compound [Fe(H2B(pz)2)2(bipy)]. This is attributed to steric hindrance between the molecules, limiting intermolecular interactions such as π–π-stacking.

Graphical abstract: Spin crossover in dinuclear iron(ii) complexes bridged by bis-bipyridine ligands: dimer effects on electronic structure, spectroscopic properties and spin-state switching

Supplementary files

Article information

Article type
Paper
Submitted
08 Mar 2024
Accepted
22 May 2024
First published
23 May 2024
This article is Open Access
Creative Commons BY license

Dalton Trans., 2024,53, 9909-9920

Spin crossover in dinuclear iron(II) complexes bridged by bis-bipyridine ligands: dimer effects on electronic structure, spectroscopic properties and spin-state switching

C. Trommer, E. Kuhlemann, T. A. Engesser, M. Walter, S. Thakur, W. Kuch and F. Tuczek, Dalton Trans., 2024, 53, 9909 DOI: 10.1039/D4DT00707G

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements