# Magnetic Anisotropy and Spin Coupling in a Cobalt(II) Dimer with Bioinspired Bridges

## TL;DR

This paper studies a cobalt dimer with bioinspired bridges to understand its magnetic properties and spin coupling.

## Contribution

The study provides detailed magnetic characterization of a hexacoordinated cobalt dimer with bioinspired ligands.

## Key findings

- The cobalt dimer exhibits a high-spin S = 3/2 configuration with strong spin–orbit coupling.
- Antiferromagnetic coupling is observed with significant magnetic anisotropy parameters (D/kB = 89 K).
- Anisotropic Landé factors confirm easy-plane magnetic anisotropy (gx = gy = 2.5, gz = 2.4).

## Abstract

Cobalt­(II) metal
complexes constitute a versatile platform
for
investigating how coordination geometry and spin–orbit coupling
determine their magnetic properties. Although numerous cobalt­(II)
coordination complexes have been reported in recent literature, only
a limited number exhibit comprehensive and quantitatively reliable
magnetic characterization. In this work, we investigate the magnetic
properties of the hexacoordinated cobalt dimer [Co2(μ-L1H)2(μ-H2O)2(H2O)4]­4NO3·2H2O, where L1H denotes the adenine
bridging ligand. The hexacoordinated environment stabilizes a high-spin S = 3/2 configuration for both Co­(II) centers, resulting
in strong spin–orbit coupling and significant zero-field splitting,
described by axial (D) and rhombic (E) anisotropy parameters. Fits to magnetic susceptibility and magnetization
data reveal antiferromagnetic coupling between the Co­(II) ions, with
a ratio of E/D ≈ 1/4 and D/k
B = 89 K, evidencing pronounced
magnetic anisotropy in the system. This behavior is further supported
by anisotropic Landé factors g

x
= g

y
= 2.5 and g

z
= 2.4,
consistent with easy-plane magnetic anisotropy.