Magnetically bistable Co(ii) and Fe(ii) complexes featuring pentyl-decorated pyridyl-benzimidazole ligands: role of isomerism and chirality

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00216305%3A26620%2F26%3A0200706" target="_blank" >RIV/00216305:26620/26:0200706 - isvavai.cz</a>

Result on the web

<a href="https://pubs.rsc.org/en/content/articlelanding/2025/qi/d5qi01269d" target="_blank" >https://pubs.rsc.org/en/content/articlelanding/2025/qi/d5qi01269d</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1039/d5qi01269d" target="_blank" >10.1039/d5qi01269d</a>

Result language

angličtina

Original language name

Magnetically bistable Co(ii) and Fe(ii) complexes featuring pentyl-decorated pyridyl-benzimidazole ligands: role of isomerism and chirality

Original language description

Three variants of 2-(pyridine-2-yl)-1H-benzimidazole bidentate ligands, with distinct pentyl substituents (n-pentyl (L1), (2S)-2-methylbutyl (L2S), and (2R)-2-methylbutyl (L2R)), were synthesized and employed to prepare magnetically bistable cobalt(ii) and iron(ii) complexes. The cobalt(ii) complexes [Co(L1)(kappa 2-NO3)2(CH3CN)] (1), [Co(L2S)(kappa 2-NO3)2(H2O)] (2S), [Co(L2R)(kappa 2-NO3)2(H2O)] (2R) and [Co(L2)(kappa 2-NO3)2(H2O)] (2rac) exhibit field supported slow relaxation of magnetisation, while the iron(ii) complexes [Fe(L2S)3](CF3SO3)2H2OCH3NO2C5H12O (3S) and [Fe(L2S)3]1.5H2O (3R) exhibit thermal spin crossover allocated above room temperature. Structural analysis revealed that the heptacoordinated cobalt(ii) complexes adopt a distorted pentagonal bipyramidal geometry, whereas the iron(ii) compounds contain hexacoordinated complex cations. Coordination compounds incorporating the chiral ligands L2S and L2R are optically active, with their enantiomeric relationship confirmed by circular dichroism spectroscopy. Computational studies provided insights into electron density distributions and bonding energetics (DFT and QT-AIM), predicted zero-field splitting parameters (CASSCF/NEVPT2), and quantified energies of the d-orbital, ligand field terms and their multiplets (via AILFT). Magnetic investigations of the cobalt(ii) complexes yielded experimental ZFS parameters and revealed distinct magnetization relaxation mechanisms: 1 exhibits relaxation governed by a phonon bottle-neck process, whereas 2S and 2R involve a combination of Raman and direct relaxation processes. Notably, compounds 2S and 2R, despite being enantiomers and isostructural, exhibited distinct relaxation dynamics, attributable to differential phonon coupling pathways modulated by the chiral substituents. This is the first report demonstrating enantiomer-dependent slow relaxation of magnetisation behaviour in cobalt(ii)-based SMMs. These findings underscore the critical role of stereochemistry in modulating spin dynamics and magnetic bistability, providing design principles for future chiral magnetic materials.

Czech name

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Czech description

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Type

J_imp - Article in a specialist periodical, which is included in the Web of Science database

CEP classification

—

OECD FORD branch

10402 - Inorganic and nuclear chemistry

Project

<a href="/en/project/GA25-16980S" target="_blank" >GA25-16980S: Passivation of layered black phosphorous with single-molecule magnets</a><br>

Continuities

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)

Publication year

2025

Confidentiality

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Name of the periodical

Inorganic Chemistry Frontiers

ISSN

2052-1553

e-ISSN

—

Volume of the periodical

12

Issue of the periodical within the volume

24

Country of publishing house

CN - CHINA

Number of pages

14

Pages from-to

8173-8186

UT code for WoS article

001562821400001

EID of the result in the Scopus database

2-s2.0-105017824542