Magnetization Slow Dynamics in Mononuclear Co(II) Field-Induced Single-Molecule Magnet

The novel tridentate ligand L (2,6-bis(1-(n-decyl)-1H-benzimidazol-2-yl)pyridine) was used for the synthesis of mononuclear Co(II) complex 1 with the general formula [Co(L)Br2]. A single-crystal X-ray structural investigation confirmed the expected molecular structure, and noncovalent contacts...

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Bibliographic Details
Published in:	Crystal growth & design Vol. 23; no. 4; pp. 2430 - 2441
Main Authors:	Malinová, Nikoleta, Juráková, Jana, Brachňaková, Barbora, Midlíková, Jana Dubnická, Čižmár, Erik, Santana, Vinicius Tadeu, Herchel, Radovan, Orlita, Milan, Mohelský, Ivan, Moncol, Ján, Neugebauer, Petr, Šalitroš, Ivan
Format:	Journal Article
Language:	English
Published:	American Chemical Society 05-04-2023
Subjects:	Chemical Sciences Coordination chemistry Cristallography
Online Access:	Get full text
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Summary:	The novel tridentate ligand L (2,6-bis(1-(n-decyl)-1H-benzimidazol-2-yl)pyridine) was used for the synthesis of mononuclear Co(II) complex 1 with the general formula [Co(L)Br2]. A single-crystal X-ray structural investigation confirmed the expected molecular structure, and noncovalent contacts were inspected by a Hirschfeld surface analysis. The electronic structure of square-pyramidal complex 1 contains an orbitally degenerate ground state which predetermines the use of the Griffith–Figgis Hamiltonian for the analysis of magnetic properties. CASSCF-NEVPT2 calculations and far-infrared magnetic spectroscopy show excellent agreement with the Griffith–Figgis Hamiltonian parameters obtained from the magnetic investigation. The high and negative value of the axial crystal field parameter Δax and the calculated g-tensor components suggest the axial magnetic anisotropy of 1. The low-temperature X-band EPR spectra were analyzed within a simplified effective spin-1/2 Hamiltonian to determine effective g-tensor components of the ground Kramers doublet, which agree with the electronic structure predicted within the CASSCF-NEVPT2 theory. An AC magnetic investigation revealed field-supported single-channel slow relaxation of magnetization with maximum relaxation time τ ≈ 28 ms at low temperatures. The comprehensive analysis of the field and temperature evolution of τ indicates that direct, Raman, and Orbach processes are all involved in slow relaxation of magnetization in 1.
ISSN:	1528-7483 1528-7505
DOI:	10.1021/acs.cgd.2c01388