Issue 44, 2021

Field-induced single ion magnet behaviour of discrete and one-dimensional complexes containing [bis(1-methylimidazol-2-yl)ketone]-cobalt(ii) building units

Abstract

We describe herein the first examples of six-coordinate CoII single-ion magnets (SIMs) based on the β-diimine Mebik ligand [Mebik = bis(1-methylimidazol-2-yl)ketone]: two mononuclear [CoII(Rbik)2L2] complexes and one mixed-valence {CoIII2CoII}n chain of formulas [CoII(Mebik)(H2O)(dmso)(μ-NC)2CoIII2(μ-2,5-dpp)(CN)6]n·1.4nH2O (3) [L = NCS (1), NCSe (2) and 2,5-dpp = 2,5-bis(2-pyridyl)pyrazine (3)]. Two bidentate Mebik molecules plus two monodentate N-coordinated pseudohalide groups in cis positions build somewhat distorted octahedral surroundings around the high-spin cobalt(II) ions in 1 and 2. The diamagnetic [CoIII2(μ-2,5-dpp)(CN)8]2− metalloligand coordinates the paramagnetic [CoII(Mebik)(H2O)(dmso)]2+ complex cations in a bis-monodentate fashion to afford neutral zigzag heterobimetallic chains in 3. Ab initio calculations, and cryomagnetic dc (2.0–300 K) and ac (2.0–12 K) measurements as well as EPR spectroscopy for 1–3 show the existence of magnetically isolated high-spin cobalt(II) ions with D values of 59.84–89.90 (1), 66.32–93.90 (2) and 70.40–127.20 cm−1 (3) and field-induced slow relaxation of the magnetization, being thus new examples of SIMs with transversal magnetic anisotropy. The analysis of their relaxation dynamics reveals that the relaxation of the magnetization occurs by the Raman (with values of the n parameter covering the range 6.0–6.8) and direct spin-phonon processes.

Graphical abstract: Field-induced single ion magnet behaviour of discrete and one-dimensional complexes containing [bis(1-methylimidazol-2-yl)ketone]-cobalt(ii) building units

Supplementary files

Article information

Article type
Paper
Submitted
23 jul 2021
Accepted
05 out 2021
First published
13 out 2021

Dalton Trans., 2021,50, 16353-16363

Field-induced single ion magnet behaviour of discrete and one-dimensional complexes containing [bis(1-methylimidazol-2-yl)ketone]-cobalt(II) building units

J. Jiménez, B. Xu, H. El Said, Y. Li, J. von Bardeleben, L. Chamoreau, R. Lescouëzec, S. Shova, D. Visinescu, M. Alexandru, J. Cano and M. Julve, Dalton Trans., 2021, 50, 16353 DOI: 10.1039/D1DT02441H

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