Iron(II) Spin Crossover Polymers of Planar N2O2 Schiff Base Templates and 4,4’-bis(pyridyl)urea Bridges
Lisa Zappe1, Charles Lochenie2, Thomas Martin3, Birgit Weber1, *
1 Department of Chemistry, Inorganic Chemistry IV, University of Bayreuth, Bayreuth, Germany
2 Institut de Science et d’Ingénierie Supramoléculaires, Strasbourg, France
3 Department of Chemistry, Inorganic Chemistry I, University of Bayreuth, Bayreuth, Germany
Abstract
Introduction:
The synthesis of four new iron(II) coordination polymers [Fe(L1a)(bpua)] (1), [Fe(L1b)(bpua)](0.5bpua) (2), [Fe(L2a)(bpua)] (3), [Fe(L1b)(bpua)](yEtOH) (5) and one trinuclear complex [{Fe(L1a)(bpua)(MeOH)}2-µ{Fe(L1a)}](xMeOH) (4) with Schiff base-like N2O2 coordinating equatorial ligands (L1a, L1b and L2a) and 4,4’-bis(pyridyl)urea (bpua) as bridging axial ligand is described.
Materials and Methods:
Single crystal X-ray structure elucidation of the trinuclear module 4 and of the coordination polymer 5 reveals the presence of HS-LS-HS chains and all-HS infinite 1-D strands, respectively. As anticipated the presence of the bridging urea supports the supramolecular concatenation within an extended hydrogen-bonding network. Magnetic measurements reveal spin crossover behavior for four of the five complexes (1 – 4) that is strongly solvent dependent.
Results and Conclusion:
Interestingly, in two cases, complete removal of the solvent from the crystal packing leads to wider thermal hysteresis loops.
Keywords: Iron, Schiff base ligand, Spin crossover, Hydrogen bonding, Polymers, Thermal hysteresis.
Article Information
Article History:
Received Date: 06/03/2018
Revision Received Date: 17/05/2018
Acceptance Date: 21/02/2019
Electronic publication date: 22/03/2019
Collection year: 2019
© 2019 Zappe et al.
open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: (
https://creativecommons.org/licenses/by/4.0/legalcode). This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
* Address correspondence to this author at the Department of Chemistry, Inorganic Chemistry II, University of Bayreuth, Bayreuth, Germany;Tel: +49 921 552555; Fax: +49 921 552157; E-mail: weber@uni-bayreuth.de
Open Peer Review Details |
Manuscript submitted on 06-03-2018 |
Original Manuscript |
Iron(II) Spin Crossover Polymers of Planar N2O2 Schiff Base Templates and 4,4’-bis(pyridyl)urea Bridges |