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Open AccessArticle

Magnetic Properties of Fe(II) Complexes of Cyclam Derivative with One p-Aminobenzyl Pendant Arm

1
Department of Inorganic Chemistry, Faculty of Science, Palacký University, CZ-771 46 Olomouc, Czech Republic
2
Department of Inorganic Chemistry, Faculty of Chemical and Food Technology, Slovak University of Technology in Bratislava, SK-81237 Bratislava, Slovakia
*
Author to whom correspondence should be addressed.
Metals 2020, 10(3), 366; https://doi.org/10.3390/met10030366
Received: 16 February 2020 / Revised: 7 March 2020 / Accepted: 9 March 2020 / Published: 12 March 2020
(This article belongs to the Special Issue Molecular Magnetism of Transition Metal Complexes)
In order to prepare an Fe(II) spin crossover (SCO) complex that could be consequently modified to a bimetallic coordination compound that possesses another magnetic property of interest, a specially designed ligand L-NH2 (1-(4-aminobenzyl)-4,11-bis(pyridine-2-ylmethyl)- 1,4,8,11-tetraazacyclotetradecane) was prepared. This ligand consists of a macrocyclic cyclam part containing two 2-pyridylmethyl pendant arms (expecting SCO upon Fe(II) complexation) and one p-aminobenzyl pendant arm with an NH2 group. The presence of this group enables the consequent transformation to various functional groups for the selective complexation of other transition metals or lanthanides (providing the second property of interest). Furthermore, the performed theoretical calculations (TPSSh/def2-TZVP) predicted SCO behavior for the Fe(II) complex of L-NH2. Thus, Fe(II) complexes [Fe(L-NH2)](ClO4)2 (1) and [Fe(L-NH2)]Cl2·6H2O (2) were synthesized and thoroughly characterized. Based on the crystal structure of an isostructural analogous Ni(II) complex [Ni(L-NH2)]Cl2·6H2O (3), the coordination number six was confirmed with an octahedral coordination sphere and a cis-arrangement of the pyridine pendant arms. The measured magnetic data confirmed the high-spin behavior of both compounds with large magnetic anisotropy (D = 17.8 for 1 and 20.9 cm−1 for 2 complemented in both cases also with large rhombicity), though unfortunately without any indication of the SCO behavior with decreasing temperature. The lack of SCO can be ascribed to the crystal packing and/or the non-covalent intermolecular interactions stabilizing the high-spin state in the solid state. View Full-Text
Keywords: spin crossover; Fe(II) complex; cyclam; macrocyclic ligand spin crossover; Fe(II) complex; cyclam; macrocyclic ligand
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MDPI and ACS Style

Drahoš, B.; Antal, P.; Šalitroš, I.; Herchel, R. Magnetic Properties of Fe(II) Complexes of Cyclam Derivative with One p-Aminobenzyl Pendant Arm. Metals 2020, 10, 366.

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