Issue 9, 2024

Effects of weak intramolecular interactions and distortions from trigonal prismatic coordination on the magnetic properties of zero-field Co(ii) single-ion magnets

Abstract

The mononuclear cobalt(II) complexes [Co(LN8)](BPh4)2·C4H10O (1-BPh4) and [Co(LN8)](NO3)2·CH3CN (2-NO3) (LN8 = 1,4,7,10-tetrakis(2-pyridinemethyl)-1,4,7,10-tetraaza-cyclododecane) have been synthesized and fully characterized. They differ well beyond a formal replacement of the counter anions, with their Co(II) centers in significantly different coordination geometries. In 1-BPh4, the Co(II) ion is not only coordinated by six N atoms from the LN8 ligand but also associated with the two remaining N atoms of LN8via weak interactions. In contrast, the Co(II) ion in 2-NO3 is only six-coordinated in a distorted trigonal prismatic geometry. Magnetic anisotropy and slow magnetic dynamics are drastically affected by these different environments around Co(II). The combination of dc magnetic data, high-frequency and -field electron paramagnetic resonance (HFEPR) and theoretical calculations unambiguously reveals large negative zero-field split (ZFS) parameters D for both complexes and a large difference between the D values. Both 1-BPh4 and 2-NO3 show slow magnetic relaxation at zero field. Magnetic dilution experiments reveal effective energy barriers of 54(4) cm−1 for 1-BPh4@Zn and 95(5) cm−1 for 2-NO3@Zn and confirm that the slow magnetic relaxation for both complexes originates from single molecule behaviour. Ab initio computational studies explain their electronic structures and the origin of the large negative magnetic anisotropy; they support the corresponding experimental observations. Further magneto-structural analyses reveal that different distortions from the ideal trigonal prismatic geometry exert drastic effects on D values and slow relaxation, and that the additional weak intramolecular interactions between Co and N reduce the axial anisotropy.

Graphical abstract: Effects of weak intramolecular interactions and distortions from trigonal prismatic coordination on the magnetic properties of zero-field Co(ii) single-ion magnets

Supplementary files

Article information

Article type
Research Article
Submitted
06 Dec 2023
Accepted
24 Mar 2024
First published
26 Mar 2024

Inorg. Chem. Front., 2024,11, 2648-2660

Effects of weak intramolecular interactions and distortions from trigonal prismatic coordination on the magnetic properties of zero-field Co(II) single-ion magnets

B. Zhang, Y. Zhou, H. Huang, X. Zhang, Y. Xiang, Y. Shi, C. Zhang, A. Yuan, X. Cai, L. Chen, Y. Zhang and Z. Hu, Inorg. Chem. Front., 2024, 11, 2648 DOI: 10.1039/D3QI02507A

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements