Issue 46, 2021

Tetranuclear Cr–Ln ferrocenecarboxylate complexes with a defect-dicubane structure: synthesis, magnetism, and thermolysis

Abstract

Using ferrocenecarboxylic acid (FcCO2H) and triethanolamine (H3tea) as ligands, the isostructural heterotrimetallic complexes [LnIII2CrIII2(OH)2(FcCO2)4(NO3)2(Htea)2]·2MePh·2THF (Ln = Tb (1), Dy (2), Ho (3), Er (4), and Y (5); Fc = (η5-C5H4)(η5-C5H5)Fe; H3tea = N(CH2CH2OH)3) were obtained. In all of the complexes which possess a defective dicubane structure, two doubly deprotonated triethanolamine ligands chelate the chromium ions. However, during the synthesis of 1, an isomeric complex 1a in which Tb3+ is chelated by triethanolamine as a tetradentate ligand, was also isolated as a few single crystals. Magnetic susceptibility measurements revealed dominant antiferromagnetic interactions in the {LnIII2CrIII2} cores of 1–4 leading to the formation of complexes with an uncompensated magnetic moment, while weak Cr–Cr ferromagnetic interactions were detected in the Y analogue. Complexes 1, 2, and 3 exhibit single-molecule magnet properties dominated by an Orbach-type relaxation mechanism with magnetization reversal barriers (Δ/kB) estimated around 54, 75, and 47 K, respectively. The Dy complex exhibits a magnetization hysteresis in an applied magnetic field at temperatures below 4 K. Thermolysis of the complexes was studied by TGA and DSC techniques; the final products obtained under an air atmosphere contain mixed oxide Cr0.75Fe1.25O3 and heterotrimetallic oxide LnCr1−xFexO3 (with x ≈ 0.75) phases.

Graphical abstract: Tetranuclear Cr–Ln ferrocenecarboxylate complexes with a defect-dicubane structure: synthesis, magnetism, and thermolysis

Supplementary files

Article information

Article type
Paper
Submitted
02 Aug 2021
Accepted
14 Sep 2021
First published
14 Sep 2021

Dalton Trans., 2021,50, 16990-16999

Tetranuclear Cr–Ln ferrocenecarboxylate complexes with a defect-dicubane structure: synthesis, magnetism, and thermolysis

P. S. Koroteev, Z. V. Dobrokhotova, A. B. Ilyukhin, E. V. Belova, A. D. Yapryntsev, M. Rouzières, R. Clérac and N. N. Efimov, Dalton Trans., 2021, 50, 16990 DOI: 10.1039/D1DT02562G

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