Issue 17, 2023

From unprecedented 2,2′-bisimidazole-bridged rare earth organometallics to magnetic hysteresis in the dysprosium congener

Abstract

The first use of the bare 2,2′-bisimidazole (H2bim) ligand in rare earth metal chemistry is presented. A series of symmetric dinuclear complexes [(Cp*2RE)2(μ-bim)] were synthesized from the salt metathesis reaction of the lithium salt Li2(bim) with Cp*2RE(BPh4) (RE = Y (1), Gd (2), Dy (3); Cp* = 1,2,3,4,5-pentamethylcyclopentadienyl). The isostructural complexes 1–3 were unambiguously characterized through elemental analysis, NMR, IR and UV/Vis spectroscopy, single-crystal X-ray diffraction, SQUID magnetometry and density functional theory (DFT) calculations. Intriguingly, the compounds are redox-inactive both on the timescale of chemical and electrochemical experiments. Herein, a rationale for the redox innocence of the bim2− ligand is provided by calculations of the electron affinity and ionization potential, both correlating well with topologically similar structures of comparable complexes. Remarkably, the Dy complex 3 shows open magnetic hysteresis loops up to 5 K which is rare for lanthanide SMMs with bridging diamagnetic entities. AC magnetic susceptibility measurements at zero field revealed slow magnetic relaxation up to 26 K leading to an effective energy barrier to spin reversal of Ueff = 154(2) cm−1 and τ0 = 5(1) × 10−8 s. The lanthanides are weakly antiferromagnetically coupled, where the J value for the Gd-congener 2 was determined to be −0.074(2) cm−1.

Graphical abstract: From unprecedented 2,2′-bisimidazole-bridged rare earth organometallics to magnetic hysteresis in the dysprosium congener

Supplementary files

Article information

Article type
Research Article
Submitted
23 Mär 2023
Accepted
13 Mai 2023
First published
31 Mai 2023

Inorg. Chem. Front., 2023,10, 4981-4992

Author version available

From unprecedented 2,2′-bisimidazole-bridged rare earth organometallics to magnetic hysteresis in the dysprosium congener

F. Benner and S. Demir, Inorg. Chem. Front., 2023, 10, 4981 DOI: 10.1039/D3QI00546A

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