Open Chemistry Journal
2019, 6 : 10-18Published online 2019 March 22. DOI: 10.2174/1874842201906010010
Publisher ID: CHEM-6-10
RESEARCH ARTICLE
Iron(II) Spin Crossover Polymers of Planar NO Schiff Base Templates and 4,4’-bis(pyridyl)urea Bridges
2 , ,
3 Department of Chemistry, Inorganic Chemistry I, , ,
*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
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.