# A Linear {FeIII 2NiII} Cluster, a Structurally Closely Related Quasi 1D {FeIII 2NiII} Chain

## TL;DR

This paper reports the synthesis of two similar iron-nickel complexes with different magnetic behaviors due to their structural differences.

## Contribution

The study demonstrates how slight structural changes in heterometallic complexes can lead to contrasting magnetic properties.

## Key findings

- A trinuclear cluster [FeIII2NiII] shows dominant ferromagnetic interactions.
- A quasi 1D chain {[FeIII2NiII]n} exhibits antiferromagnetic interactions.
- Structural similarity does not guarantee similar magnetic behavior in these complexes.

## Abstract

The solvothermal reaction between FeCl3·6H2O, NiCl2·6H2O, 2‐hydroxynaphthaldehyde, and glycine (gly) in MeOH results in the formation of the trinuclear heterometallic cluster [FeΙΙΙ
2NiΙΙ(L1)4(MeOH)4] (1) in good yield, while the same reaction upon replacing gly with methyl‐alanine (mAla), results in the formation of the closely related quasi 1D coordination polymer {[FeΙΙΙ
2NiΙΙ(L2)4(MeOH)2]n} (2) (L1, L2: the dianionic form of the Schiff‐base ligand derived from the condensation of 2‐hydroxynaphthaldehyde and gly (L1 for 1), or mAla (L2 for 2)). The structure of 1 describes a linear trimetallic {FeIII
2Ni} unit, whereas complex 2 consists of repeating linear {FeIII
2Ni} units with each one connected to two neighboring units via four coordination bonds, forming a quasi‐1D chain. The structural similarity between complex 1 and the repeating unit of complex 2 is remarkable. However, their magnetic properties differ significantly, with complex 1 displaying dominant ferromagnetic interactions, and complex 2 showing antiferromagnetic interactions.

The synthesis, characterization, and magnetic properties of two closely related heterometallic {FeIII
2NiII} species are reported, upon employment of suitable amino acid Schiff‐base ligands; a discrete {FeIII
2NiII} trimetallic cluster and a {FeIII
2NiΙΙ}n chain. Despite their striking structural similarity, they display contrasting magnetic properties, with the former showing ferromagnetic and the latter antiferromagnetic behavior.